5.CHEMICAL REVIEW

Hydrogen Production Reactions from Carbon Feedstocks:

Fossil Fuels and Biomass

R.M.Navarro,M.A.Pen?a,and J.L.G.Fierro*

Instituto de Catalisis y Petroleoquimica,CSIC,Cantoblanco,28049Madrid,Spain

Received December1,2006

Contents

1.Introduction3952

2.Reactions with Carbon Dioxide and Carbon

Monoxide Coproduction

3954

2.1.Steam Re-forming3954

2.1.1.Methane3954

2.1.2.Liquid Hydrocarbons3958

2.1.

3.Methanol3960

2.2.Catalytic Partial Oxidation3961

2.2.1.Methane3961

2.2.2.Liquid Hydrocarbons3964

2.2.

3.Methanol3964

2.3.Autothermal Re-forming3966

2.3.1.Methane3966

2.3.2.Liquid Hydrocarbons3967

2.3.3.Methanol3967

2.4.Gasification of Coal and Heavy Hydrocarbons3968

2.4.1.Chemistry3968

2.4.2.Gasification with Simultaneous CO2

Capture

3968

https://www.wendangku.net/doc/b517376073.html,mercialization Status of Fuel Re-formers3969

2.5.1.Steam Methane Re-formers3969

2.5.2.Partial Oxidation,Autothermal,and

Methanol Re-formers

3970

2.5.

3.Novel Re-former Technologies3971

3.Carbon Dioxide-free Reactions3971

3.1.Methane Decomposition3971

3.1.1.Catalysts3972

3.1.2.Catalyst Deactivation and Regeneration3972

3.2.Theoretical Analysis of Methane

Decomposition on Metal Surfaces

3973

3.3.Methane Aromatization3974

3.3.1.Catalysts3974

3.3.2.Reaction Mechanism3975

3.3.3.Coke Formation3975

4.Carbon Dioxide Neutral Alternatives3976

4.1.Biomass Conversion3976

4.1.1.Steam/Oxygen Gasification3976

4.1.2.Gasification in Supercritical Water3977

4.1.3.Gasification with Simultaneous CO2

Capture

3979

4.2.Re-forming of Biomass-Derived Products3979

4.2.1.Ethanol3979

4.2.2.Sugars3981

5.Secondary Reactions in Hydrogen Production

Schemes

3982

5.1.Hydrogen Production from CO3982

5.1.1.Water Gas Shift Reaction3982

5.2.CO Removal Reactions3984

5.2.1.Preferential CO Oxidation3985

6.Future Opportunities3985

7.Acknowledgments3987

8.References3987 1.Introduction

Hydrogen is one of the most common elements in Earth’s crust,but it does not occur to a significant extent in elemental form.It is mostly present in water,biomass,and fossil hydrocarbons.Hydrogen is considered as a nonpolluting, inexhaustible,efficient,and cost-attractive energy carrier for the future.Hydrogen gas is a versatile energy carrier that is currently produced from a variety of primary sources such as natural gas,naphtha,heavy oil,methanol,biomass,wastes, coal,solar,wind,and nuclear.1-4It is a clean energy carrier because the chemical energy stored in the H-H bond is released when it combines with oxygen,yielding only water as the reaction product,althought nitrogen oxides(NO x)can also form during high-temperature combustion in air.Ac-cordingly,a future energy infrastructure based on hydrogen has been perceived as an ideal long-term solution to energy-related environmental problems.5,6

It is generally understood that the renewable energy-based processes of hydrogen production(solar photochemical and photobiological water decomposition,electrolysis of water coupled with photovoltaic cells or wind turbines,etc.)would be unlikely to yield significant reductions in hydrogen costs in the next few years.Industry generates some48million metric tons of hydrogen globally each year from fossil fuels. Almost half of this hydrogen goes into making ammonia,7a major component of fertilizers and a familiar ingredient in household cleaners.Refineries use the second largest amount of hydrogen for chemical processes such as removing sulfur from gasoline and converting heavy hydrocarbons into gasoline or diesel fuel.Food producers use a small percentage of hydrogen to add to some edible oils through a catalytic hydrogenation process.8,9

The demand for hydrogen in the next decade,both for traditional uses,such as making ammonia,and for running fuel cells,is expected to grow.10,11In fact,many car manufacturers already have produced prototype vehicles powered by hydrogen fuel cells.At least in the near future, this thirst for hydrogen will be quenched primarily through

*Author to whom correspondence should be addressed(fax+3491585

4760;e-mail jlgfierro@icp.csic.es).

3952Chem.Rev.2007,107,3952?3991

10.1021/cr0501994CCC:$65.00?2007American Chemical Society

Published on Web08/23/2007

the use of fossil fuels.To make hydrogen,industry uses steam methane re-forming(SMR),which is the most widely used and most economical process.12Although SMR is a complex process involving many different catalytic steps, as long as natural gas(or CH4)remains at low or even moderate cost,including the advent of a carbon tax,SMR will continue to be the technology of choice for massive production of H2.Over several decades of developments in catalyst technology,substantial improvements have been introduced.The SMR process also gives off carbon monoxide and carbon dioxide,the primary greenhouse gas.Although this approach generates pollution,these gases are released in a potentially more manageable way rather than in the case of billions of automobile engines.A novel re-forming technology,the membrane reactor(MR),is currently being developed13and promises economic small-scale hydrogen production combined with inexpensive CO2capture because of the high concentration and pressure of the exiting gas stream.14This could avoid a dedicated hydrogen infrastruc-ture,facilitate CO2capture at small scale,and thus,possibly, contribute to a more rapid cut in greenhouse gas emissions. Because it is expected that significant development of a hydrogen transportation infrastructure will not occur within the next decade,15the time frame of this study is the medium-term future(2015-2025).

Nonetheless,shedding the habit of fossil fuel entirely is the only way a wholesale shift to hydrogen will work in the long term.One approach to this goal is to apply steam re-forming methods to alternative renewable materials.Such materials might be derived from plant crops,agricultural residues,woody biomass,etc.Not only do these biomass conversion schemes turn low-value feedstocks into a valuable product,but carbon dioxide released in the processes is slowly recycled by the planting of new crops to provide the needed biomass,even though time constants of the carbon

Rufino M.Navarro received his bachelor’s degree in industrial chemistry at the Complutense University of Madrid,Spain,in1992.He started his research in applied catalysis at the Institute of Catalysis and Petrochemistry in1994.He obtained his doctor of chemistry degree from the Autonomous University of Madrid in1998with a dissertation on the development of catalysts for deep hydrodesulfurization of diesel fuels under the direction of Prof.J.L.G.Fierro and Dr.B.Garcia Pawelec.After receiving his Ph.D.degree,he was recruited as a postdoctoral fellow in the Laboratoire Catalyse et Spectrochimie(CNRS,Caen,France,1998?1999)with Dr. J.Leglise.At the end of this period he was appointed as a postdoctoral associate of the Institute of Catalysis and Petrochemistry,where he focused on hydrogen production from hydrocarbons and low molecular alcohols using traditional technologies.He assumed his current position of tenure scientist at the Institute of Catalysis and Petrochemisty in2006.His research activities focus on heterogeneous catalysis applied to clean energy production:fuel hydrotreatments,hydrodesulfurization,hydrogena-tion of aromatics,hydrogen production,re-forming of hydrocarbons and alcohols,water gas shift,and preferential oxidation of CO.

Miguel A.Pen?a received his M.Sc.in chemistry in1985from the Complutense University of Madrid,Spain.He obtained his Ph.D.in chemistry in1990at the same university,working under the supervision of Dr.L.Gonza′lez Tejuca and Prof.J.L.G.Fierro at the Institute of Catalysis and Petrochemistry(CSIC).From1990to1993,he was working under contract in a project of oxidative coupling of methane funded by REPSOL(the largest Spanish oil and petrochemistry company).At the end of this period,he took a staff position of researcher at the Institute of Catalysis and Petrochemistry,which is his current status.In1996?1997he was a Visiting Scholar in the group of Prof.A.Varma,at the University of Notre Dame(USA).Currently,he is secretary of the Hydrogen Spanish Association.His research interests are focused mainly in catalytic processes for clean energy production,specifically in catalytic applications of perovskite oxides(Ph.D.dissertation),natural gas conversion,catalytic combustion,C1chemistry,catalytic membrane reactors,hydrogen produc-tion,and fuel cell catalysts.He has published50papers,is the co-inventor of five patents,and has made30presentations at symposia and conferences.Jose L.G.Fierro was graduated in chemistry from the University of Oviedo (Spain)in1973and received his Ph.D.degree in chemistry from the Complutense University of Madrid(Spain)in1976.He developed postdoctoral positions in the Department of Surface Chemistry at the Universite′Pierre et Marie Curie,Paris(France),and in the Department of Chemistry of Cork University,Cork(Ireland),and took a sabbatical leave in the Groupe of Physico-Chimie Mine′rale et de Catalyse of the Universite′Catholique de Louvain,Louvain-la-Neuve(Belgium).In1988 he reached the position of professor in the Institute of Catalysis and Petrochemistry(CSIC).His activities cover different fields of catalysis such as natural gas conversion,selective oxidations of paraffins and olefins, synfuels,environmental catalysis,catalytic combustion,surface chemistry, heteroatom removal and dearomatization of petroleum feedstocks,catalyst preparation,hydrogen production,high-temperature chemistry,and chemi-cal and physical characterization of solid catalysts.His scientific achieve-ments are compiled in730papers spread in prestigious refereed journals, 12reviews,8books(editor and/or coauthor),and20patents.He has been invited to more than200plenary lectures,seminars,and conferences in refining and petrochemical companies,specialized symposia,and public and private organizations all around the world.

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cycle are different.A biomass strategy of hydrogen genera-tion could be a useful intermediate step between the current fossil fuel method and the dream of efficient water splitting. Still,any realistic contender for hydrogen generation must first suppress the re-forming of fossil fuel as the cheapest and most efficient process.

Despite the compelling attractiveness of hydrogen,the realization of a hydrogen economy faces many challenges. Perhaps the most important one is the near absence of large-scale supporting infrastructure for hydrogen distribution. Interest in hydrogen grew after World War I,but it was in 1970that General Motors engineers coined the term“hy-drogen economy”.16Recently,many worldwide agencies have described hydrogen as the future fuel of choice.17The International Energy Agency described a Hydrogen Program with detailed development activities.The report describes technical options for small-scale production of hydrogen via steam re-forming of natural gas or liquid fuels.Its focus is on small stationary systems that produce pure hydrogen at refueling stations for hydrogen-fueled vehicles.18,19 Although hydrogen production and storage/distribution infrastructures are commercially available in chemical and refining industries around the world,existing conversion and storage technologies are too expensive for widespread use in energy schemes.Finally,as a general rule,the existing energy policies do not promote consideration of environ-

mental and security costs of energy that would facilitate wider use of hydrogen.Developing hydrogen as a realistic, viable energy option will require an unprecedented level of sustained and coordinated activities at different levels.This area remains a fertile ground for improvements.As can be seen in the sections below,recent important approaches to hydrogen production involve methane decomposition,partial oxidation,and CO2re-forming of methane,together with the re-forming of low molecular weight alcohols such as methanol and ethanol.There are a few relatively complete reviews covering this field.1-3A review in2002by Rostrup-Nielsen et al.20provided a coherent description of the catalysis of the re-forming reactions.More recently,Ross21 summarized the steam re-forming and CO2re-forming reactions,discussing some catalysts developed for these reactions.

2.Reactions with Carbon Dioxide and Carbon Monoxide Coproduction

2.1.Steam Re-forming

The steam re-forming of hydrocarbon feedstocks(eq1) has for many decades been the preferred method used industrially for the production of hydrogen either as a pure gas or as a reactant for the production of ammonia or methanol.20,22Generally,the steam re-forming process in-volves two reactions,namely,the splitting of hydrocarbons with steam(eq1)and the water gas shift(WGS)(eq2):23

The steam re-forming process has been practiced since1930. The first plant using light alkanes as feed began operation in1930at Standard Oil Co.in the United States and6years later at ICI in Billingham,England.22In the United States,where natural gas was available,methane steam re-forming had been performed.By contrast,in Europe during the1950s, light naphtha became the most economic https://www.wendangku.net/doc/b517376073.html,ter, however,the discovery of natural gas reserves in The Netherlands and under the North Sea changed the feedstock situation.Due to its importance,substantial improvements have been introduced over the years,and research on catalysts,reactor materials,fluidodynamics,and heat trans-port continues.

2.1.1.Methane

2.1.1.1.Reaction and Mechanisms.The transformation of methane to hydrogen has been a challenging task because methane is extremely difficult to activate.Among hydro-carbons,the methane molecule has the largest H/C ratio(H/C )4),substantially higher than that of n-heptane(H/C)2.3),

the boiling point of which falls in the range of gasoline hydrocarbons,and much higher than that of a highly condensed polyaromatic structure such as coronene(H/C)

0.5)(Figure1).The methane molecule is very stable,with

a C-H bond energy of439kJ/mol;hence,methane is resistant to many reactants.In the methane molecule the sp3 hybridization of the atomic orbitals of carbon makes the carbon-hydrogen bonds very strong.Methane is readily activated by group8,9,and10metals and is oxidized to give syngas(CO+H2)first and then hydrogen after WGS and CO2removal.Syngas is cooled and then shifted in the WGS reactor.In older plants,CO2is subsequently removed by means of a chemical absorption unit.Modern hydrogen plants apply pressure swing adsorption(PSA)to separate hydrogen from the other components,which produces higher quality hydrogen(99.999%against95-98%for scrubbing systems)at feedstock pressure(ca.25bar).24The integration of ceramic ion transport membranes with re-formers opens new possibilities for highly efficient and low-cost hydrogen production with CO2capture in the long term.25

The SMR reaction(eq1)is highly endothermic and favored at lower pressures.The steam re-forming catalysts

C n H m+n H2O f n CO+(n+m/2)H2

for n)1:?H°298K)+206.2kJ/mol(1) CO+H2O f CO2+H2?H°298K)-41.2kJ/mol(2)Figure1.H/C atomic ratios in different hydrogen-containing molecules.

3954Chemical Reviews,2007,Vol.107,No.10Navarro et

al.

usually contain nickel as the major metallic component.The noble metal catalysts were first used for steam re-forming,but the cost makes their use prohibitive.For these systems,the catalytic activity depends on the metal area,and their properties are dictated by the severe operating conditions such as temperatures in the range of 700-1250K and steam partial pressures of up to 30bar.The actual activity of the catalyst is not,in general,a limiting factor.Thus,a typical nickel catalyst is characterized by a turnover frequency (TOF)of ca.0.5s -1at 723K under conditions approaching industrial practice,which corresponds to CH 4conversions around 10%.The main barrier of the steam re-forming reaction is thermodynamics,which determines very high conversions only at temperatures above 1170K.In practice,a significant part of the catalyst loaded into the tubes of the re-former is poorly utilized.The catalyst activity is important but not decisive,with the heat transfer coefficient of the internal tube wall being the rate-limiting parameter.22

Kinetics of methane steam re-forming catalysis are re-ported and summarized by Rostrup-Nielsen et al.22and Wei and Iglesia,26who concluded that CH 4reaction rates are limited solely by C -H bond activation steps and unaffected by the identity or concentration of co-reactants.According to these studies the following mechanism was proposed:

In eqs 3a -3g *denotes a Ni surface atom.According to this mechanism,H 2O reacts with surface Ni atoms,providing adsorbed oxygen and gaseous hydrogen;methane adsorbs dissociatively on the Ni surface,forming a methyl group that undergoes further stepwise dehydrogenation steps.CH -species formed in this way react with adsorbed oxygen and finally yield gaseous CO and H 2.

2.1.1.2.Carbon Formation.In the production of H 2from methane,carbon formation usually takes place in the form of fibers or filaments with a small Ni particle at the top of each fiber.3,27Carbon formation may lead to breakdown of the catalyst together with carbon deposits and degradation of the catalysts.There are two major reactions for carbon formation:

The tendency to form carbon on the catalyst surface depends on reaction kinetics,process conditions,and re-former design.3,22These C-forming reactions are carefully balanced by C-consuming reactions (C +CO 2f 2CO and C +H 2O f CO +H 2),which in turn also depend on the kinetic process conditions and reactor design (Figure 2).At low temperatures,the activated Ni catalyst is covered by a

hydrocarbon layer,which slowly degrades into a polymeric film,blocking the nickel surface.At high temperatures,ethylene from the pyrolysis of higher hydrocarbons produces pyrolytic coke,which encapsulates the catalyst particles.Whisker carbon is the most common form of carbon produced during the steam re-forming.22

Nickel carbide is not stable under SMR conditions.As a consequence,carbon nucleates in the form of filaments after an induction period,and then the carbon filament grows at a constant rate (Figure 3).The importance of step sites on the catalyst surface for the nucleation of carbon was recently confirmed by in situ investigations by high-resolution transmission electron microscopy (TEM).These indicate the segregation of carbon when the formation of filaments takes place at specific sites on the nickel surface.20The size of Ni particles has a direct implication on the nucleation of carbon.The initiation of carbon formation is retarded on the smaller nickel crystallites,as demonstrated by thermogravimetric experiments with two Ni catalysts having the same activity but different metal dispersions.28

The rate of carbon formation was lower on noble metals than on nickel,29and this behavior appears to be related to the difficulty of noble metals to dissolve carbon in the bulk.30The carbon formed on the surface of noble metals is almost indistinguishable from the catalyst particles.High-resolution TEM images taken from a ruthenium catalyst employed in the SMR reaction reveal a structure in which a few carbon layers are deposited on the surface of the Ru particles.29Several approaches can be followed to minimize coke formation on Ni or other metal surfaces.The first rests on the ensemble size control.31The formation of carbon s either dissolved in or deposited on the nickel s must require the polymerization of monoatomic carbon species (C R ),whereas gasification involves only one of such species.The formation of more than one species demands more surface sites.Because the SMR requires the dissociation of methane to

H 2O(g)+*f O*(a)+H 2(g)(3a)CH 4(g)+2*f CH 3*(a)+H*(a)(3b)CH 3*(a)+*f CH 2*(a)+H*(a)(3c)CH 2*(a)+*f CH*(a)+H*(a)(3d)CH*(a)+O*(a)f CO*(a)+H*(a)

(3e)CO*(a)f CO(g)+*(3f)2H*(a)f H 2(g)+2*

(3g)

2CO f C +CO 2?H °298K )-172.5kJ/mol (4)CH 4f C +2H 2

?H °298K )+74.9kJ/mol

(5)

Figure 2.Carbon formation and gasification routes during the steam re-forming of methane.Adapted with permission from ref 23.Copyright 1997Elsevier

B.V.

Figure

3.Schematic illustration of the process by which carbon whiskers are formed at the nickel particle during steam re-forming.

Hydrogen Production Reactions from Carbon Feedstocks Chemical Reviews,2007,Vol.107,No.103955

form a carbonaceous intermediate,coke formation would require an ensemble of surface sites that would be larger than that required for the re-forming reaction.Following this reasoning,it was inferred that by controlling the number of sites in a given ensemble it may be possible to minimize coke formation while maintaining the re-forming reaction. The basis of the ensemble size control lies in the work of Alstrup and Andersen32on sulfur adsorption on nickel.Those authors found that the grid sulfur did not coincide with the nickel atoms placed in the topmost layer of nickel crystallites. Adsorption of sulfur on the catalyst surface thus delineates ensembles of sites,with the critical size being reached at sulfur coverage above0.7.Under these conditions,the rate of the steam re-forming reaction was decreased but coke formation was almost eliminated.Although sulfur adsorption is strong,it is diminished during reaction.As a result,it is necessary to add small amounts of a sulfur-producing gas to the feed.

The second approach to the control of coke formation is to prevent carbide formation.33The electronic structure of carbon is similar to that of sulfur and the tetra-and pentavalent p metals(Ge,Sn,and Pb or As,Sb,and Bi). The tetra-or pentavalent metals could also interact with Ni 3d electrons,thereby limiting the possibility of nickel carbide formation.33Alloy formation reduces carbide formation but is undesirable as active sites on the surface of nickel crystallites are lost.However,carbide formation can be developed only on the surface layer,and as a result an alloy formed at the surface layer should be preferred.On the basis of these ideas,Trimm33studied the effect of small amounts of dopants on the catalytic and coking behavior of nickel catalysts.The effect of tin on steam re-forming was small for Sn levels below1.75%,whereas coke formation was significantly reduced even by the addition of0.5%Sn.It is clear that the addition of small amounts of dopant does substantially reduce coking while having little influence on the rate of the steam re-forming reaction.Alloying nickel with copper can also reduce carbon formation,34but it is not feasible to reach the required high surface coverage of copper atoms,as occurs with sulfur atoms,to remove carbon deposition.The formation of a stable alloy between nickel and tin,35or nickel and rhenium,36also appears to be responsible for the reduction in carbon formation.All of these studies have shed some light on the improvement of catalyst performance in the steam re-forming reactions.However, additional work is required to understand the promoting effects of various oxides and to discern whether or not the promoters decorate the surface of nickel crystallites.

2.1.1.

3.Promoter Effects.The catalysts are promoted to reduce the risk of carbon formation.Several recent investiga-tions have reported the effect of catalyst composition on the activation of methane.Upon looking at the degree of dehydrogenation of CH x species(measured by the number of hydrogen atoms per carbon atom)on several metals,it was observed that x was larger for nickel than for cobalt catalysts and also larger for magnesia-supported than for silica-supported catalysts.37Kinetics experiments revealed that MgO and alkali dissociate steam,which then transfers to the nickel particles through a spillover mechanism.22A similar conclusion was reached from isotope-exchange experiments,38which demonstrated that the enhanced adsorp-tion of water on magnesia support leading to improved resistance to carbon formation is by nature a dynamic effect. The spillover of water probably takes place through OH groups instead of molecular water.In favor of this possibility, in a recent study on Ni/MgO and Ni/TiO2catalysts Bradford and Vannice39concluded that surface hydroxyl groups, located on the support surface,react with the CH x fragments adsorbed on the nickel surface to yield a formate-type intermediate which decomposes into H2and CO.These authors also suggested that the support may serve as a sink for surface hydroxyl groups and that the active site for CH x O formation and subsequent decomposition may be at the metal-support interface.Activation barriers were found to be higher on Ni/TiO2after significant time on-stream,and this was attributed to a geometric site blockage mechanism whereby migrating TiO x moieties or inactive carbon deposits break up the large site ensembles on the nickel surface needed for CH4dissociation.The use of supports able to release bulk oxygen such as yttria-stabilized zirconia indi-cates that a spillover of lattice oxygen may be involved in the re-forming reaction.40

2.1.1.4.CO2(Dry)Re-forming.At the beginning of the past decade interest arose in so-called“dry re-forming”,the re-forming of methane to syngas using CO2as a reactant41 (eq6).Carbon dioxide re-forming is typically influenced by the simultaneous occurrence of the reverse water gas shift (RWGS)reaction(eq7),which results in H2/CO ratios of less than unity.

This reaction had been first studied by Fischer and Tropsch in1928.42In a series of papers in the1960s,Bodrov et al.43 had also demonstrated that the steam re-forming and CO2 re-forming reactions over Ni materials had very similar kinetics and mechanisms.The reaction is notoriously prone to giving carbon deposition,the chemical potential for carbon deposition for the stoichiometric dry re-forming reaction being significantly higher than that in the equivalent steam re-forming reaction.44The renewed interest in the early1990s arose because several catalysts(e.g.,noble metals supported on alumina45)were reported to be effective for the reaction without exhibiting the serious problems of carbon deposition found with the more conventional catalysts such as Ni supported on alumina.Most of the papers related to CO2 re-forming were introduced with the argument that the discovery of an effective catalyst would lead to a solution to the greenhouse effect.This is untrue because at the end, after the shift reaction,1mol of CO2consumed yields2 mol of CO2(eq6).Nevertheless,the research led to a new understanding both of the conditions under which dry re-forming or a combination of dry re-forming and steam re-forming could be carried out and of the catalysts to be used. The active catalysts,the reaction mechanisms,and the deactivation processes are similar for steam re-forming and dry re-forming reactions of methane.41,46The conversion of methane is restricted by the thermodynamics of re-forming reaction.The calculated thermodynamic conversion of methane for various CO2/CH4ratios as a function of temperature is shown in Figure4.21Assuming that the ratio chosen for operation will be close to unity,it can be seen that reasonable conversions will be achieved only at high temperatures(above ca.1120K).The reaction is more endothermic than steam re-forming and must be carried out at high temperature and low pressure to achieve maximum CH4+CO2f2CO+2H2?H°298K)+247.4kJ/mol

(6)

CO2+H2f CO+H2O?H°298K)+41.2kJ/mol

(7)

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conversion.Nickel30,47and noble metals30,48,49are active for the dry re-forming.In addition,perovskite oxides50,51and transition metal carbides(especially Mo)have been con-sidered for CO2re-forming,52-54although under reaction conditions the later systems seem to be stable only at high pressure.

Several attempts have been made to understand the mechanism of CH4re-forming with CO2on group8,9,and 10metals.Most of these employ supported platinum catalysts because Pt appears to be one of the most active and stable metals for these reactions.55-57Platinum supported on zirconia,for instance,has been used for the dry re-forming of CH4for500h without detectable deactivation.57,58 Recently,Wei and Iglesia59reported an isotopic tracer and kinetic study aimed at probing the identity and reversibility of the elementary steps required for H2O and CO2re-forming of CH4on supported Pt clusters and to demonstrate the mechanistic equivalence for H2O and CO2re-forming and CH4decomposition reactions.Re-forming rates were limited by C-H bond activation of CH4molecule on essentially uncovered Pt crystallite surface unaffected by the concentra-tion or reactivity of CO2co-reactant.Kinetic isotopic effects appeared to be consistent with the sole kinetic relevance of C-H bond activation(k H/k D)1.58-1.77at873K).These isotope effects and measured activation energies were similar for H2O re-forming,CO2re-forming,and CH4decomposition reactions.CH4/CD4cross-exchange rates are much smaller than the rate of methane conversion in the CO2and H2O re-forming reactions,and thus C-H bond activation steps are irreversible.

For the supported platinum catalysts,turnover frequencies (TOF)for H2O and CO2re-forming and CH4decomposition increase with increasing platinum dispersion,suggesting that coordinative unsaturated surface Pt atoms,present in small crystallites,are more reactive than Pt atoms in a low index surface for C-H bond activation.Platinum dispersion,but not TOF,is influenced by the type of support(Al2O3,ZrO2, Zr1-x Ce x O).59This indicates that co-reactant activation on supports,if it occurs,is not kinetically relevant.The rates of structure-insensitive CO oxidation reaction are found to be similar before and after CH4re-forming,and hence this latter reaction does not influence the number of exposed Pt atoms via coverage or sintering by unreactive chemisorbed species.These mechanistic conclusions and metal dispersion effects appear to apply generally to CH4reactions on group 8,9,and10metals,59but the reactivity of surface Pt atoms in C-H bond activation reactions is greater than for similar crystallite size of other metals.

Others have proposed that in the mechanism for CO2re-forming,CH4and CO2are activated in different ways, depending on active metal.60-62Schuurman et al.60studied Ni and Ru supported on SiO2and Al2O3by temporal analysis of products(TAP).CH4is activated by decomposition in both metals,producing H2and adsorbed carbon.However, the behavior of CO2is different on each metal.CO2is adsorbed on Ni,yielding CO and adsorbed oxygen;O ads and C ads react later via a Langmuir-Hinshelwood mechanism to form CO:this is the rate-determining step.Nevertheless, on Ru,CO2reacts directly with C ads(Eley-Rideal mecha-nism)to produce CO.No adsorbed oxygen is present in this case,and the rate-determining step is the adsorption of methane.Other authors61-63also postulated that the reaction is not occurring solely on the noble metal surface but primarily on the metal-support interfacial region.Thus,a bifunctional mechanism has been proposed for CO2re-forming of CH4over a Pt/ZrO2catalyst.63In this mechanism (Figure5),a molecule of methane reacts at the Pt surface to give carbon species and hydrogen is desorbed.Some of the carbon accumulates on the surface of the Pt crystallite,but some diffuses to the interface between the Pt and the zirconia support,where it picks up oxygen from the support and desorbs as CO.The oxygen of the support is then replaced by the reaction of a molecule of CO2with desorption of a further molecule of CO.

The major difficulty associated with the realization of dry re-forming is the thermodynamically favored formation of coke,which deactivates the catalysts.Thermodynamics predicts formation of coke under usual conditions of CO2 re-forming via either CH4decomposition or CO dispropor-tionation.The catalysts are promoted to reduce the risk of carbon formation by means of(i)enhancing the adsorption of CO2,(ii)enhancing the rates of surface reactions,and (iii)decreasing the rate of methane activation.The porous structure of the support also influences the stability of the metal.On comparing R-Al2O3withγ-Al2O3,SiO2,and MgO of different porosities,Lu et at.64,65concluded that porous supports favor metal dispersion and contact between the active sites and reactants,increasing the activity for CO2re-forming and stability.Zhang et al.66found that the activity for CO2re-forming in supported Rh catalysts follows the order YSZ>Al2O3>TiO2>SiO2>La2O3>MgO,which is directly correlated with the acidity of the support. Deactivation is controlled by other parameters,becausesince in a specific support it decreases when the particle size of Rh increases.Nevertheless,the nature of the support has a stronger influence on the catalytic lifetime,which is low on TiO2and MgO within the mentioned support series.The enhanced adsorption of CO2on supports67seems to be important for the promoting effect when using basic materials

Figure4.Thermodynamically calculated conversions of methane as a function of temperature for a series of different feed ratios. Adapted with permission from ref21.Copyright2005Elsevier B.V.Figure5.Model for CO2re-forming of CH4over a Pt/ZrO2 catalyst.Adapted with permission from ref63.Copyright1998 Elsevier B.V.

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(La2O3,CeO2)as supports for dry re-forming catalysts. Increasing the concentration of adsorbed CO2is suggested to reduce carbon formation via CO disproportionation. Manganese also promotes Ni/Al2O3for CO2re-forming by decreasing carbon deposition.68In this case,Ni particles are partially covered by MnO x patches,and their role is to promote the adsorption of CO2,producing a reactive carbon-ate.This carbonate reacts with the CH x fragments,preventing coke from being formed form these fragments.Additionally, the MnO x patches break the Ni ensemble necessary for carbon formation,without reducing the activity of the catalyst.Carbon formation during CO2re-forming of CH4 also depends on the choice of metal.Bradford and Vannice61 studied different CO2re-forming active metals(Ni,Co,Fe, Rh,Pd,Ir,Pt)supported on TiO2and SiO2.The TOF depended on the d-character of the transition metal.In general,it has been found that Ru,Rh,and Ir supported on Eu2O3,48Mg,69and Al2O345exhibit much less carbon formation than supported Ni,Pd,and Pt.A beneficial effect of the addition of Sn to Pt has been described.35Pt-Sn/ SiO2and Pt-Sn/ZrO2exhibit less carbon deposition during CO2re-forming than the respective monometallic Pt catalyst analogues.The reason for this behavior is possibly the formation of a Pt-Sn alloy and remains under investigation.

2.1.2.Liquid Hydrocarbons

The wide availability of gasoline,diesel fuel,and jet fuels would make them ideal as fuels for hydrogen production.70 Logistic liquid fuels are multicomponent mixtures containing a large number of hydrocarbons:paraffins,naphthenes, olefins,aromatics,and sulfur compounds71,72(Table1).The chemical nature of fuel mixtures poses several technical problems to the re-forming process;these are associated with (i)the presence of sulfur compounds,which may deactivate catalytic active sites,and(ii)the strong tendency for carbon to be deposited on catalytic surfaces under re-forming conditions

2.1.2.1.Catalytic Reaction and Mechanism.Steam re-forming of liquid fuels is performed over catalysts normally containing group8,9,and10metals(Ni,Co,Ru,Pt,Pd, Rh,etc.).The reaction of the hydrocarbons present in fuels with steam takes place by irreversible adsorption on catalyst surfaces with no intermediate formation.73The adsorbed hydrocarbon undergoes subsequent breakage of C-C bonds one by one until the hydrocarbon has been converted into C1compounds.The steam re-forming reaction(eq1)is followed by the establishment of the equilibria of the exothermic water gas shift reaction(eq2)and the metha-nation reaction(eq8):

Hydrocarbons present in fuel feeds showed pronounced differences in reactivities in steam re-forming.22Long-chain hydrocarbons and olefins are more reactive than CH4.Also, cycloalkanes are more reactive than methane.However,in the case of aromatics,due to the stable resonant structure of the rings,reactivity toward steam approaches that of CH4.

2.1.2.2.Catalyst Sulfur Poisoning.The catalyst formula-tions used for liquid fuel steam re-forming are more complicated than those used for methane steam re-forming because they must be carefully formulated to achieve high resistance to both carbon deposition and sulfur poisoning. The metals included in re-forming catalysts(groups8,9, and10)are highly susceptible to sulfur poisoning.Under re-forming conditions,sulfur compounds presents in fuel (10-50ppm)react under re-forming conditions with metals, forming stable metal sulfides that deactivate the catalyst.74,75 The desulfurization of natural gas(hydrogenation of alkyl thiol compounds and the subsequent adsorption/absorption of H2S)is almost quantitative.However,desulfurization of the organic S compounds present in liquid hydrocarbon fuels (derivatives of dibenzothiophene)partly removes sulfur,even using novel hydrotreating catalysts or by deep adsorptive desulfurization.76Much work has been done to better understand the sulfur poisoning on Ni-based and noble metals-based catalysts.However,no highly active sulfur-tolerant steam re-forming catalyst has been developed,and only a few papers have been published in the area of catalysts with improved sulfur resistance.77,78Bimetallic Ni-Re catalysts have shown promising sulfur tolerance for the steam re-forming of mixture of hydrocarbons simulating gasoline in the presence of20ppm of S in the feed.77Also,catalysts based on Rh-Ni supported on CeO2-modified Al2O3have been presented as excellent catalysts that can successfully re-form sulfur-containing liquid hydrocarbons,such as jet fuel,as demonstrated by the re-forming of JP-8containing 22ppm of sulfur without deactivation for100h time-on-stream.78

2.1.2.

3.Carbon Formation on Catalyst Surface.In the steam re-forming of higher hydrocarbons,the coke formation is much higher than with methane.33Rostrup-Nielsen and Tottrup79have reported data for a range of hydrocarbons (Figure6)showing that olefins and aromatics,in particular, have the highest tendency for coke formation.Olefins are not normally present in the feedstock,but they may easily be formed by thermal pyrolysis of hydrocarbons during preheating at temperatures exceeding873-973K.80

The carbon formation from thermal pyrolysis may be solved through adiabatic pre-re-forming(see section1.2.1.5) prior to deployment of the primary re-former or by the use of cool flames to evaporate liquid hydrocarbon mixtures without carbon residues.81However,steam re-forming of liquid feeds containing up to30wt%aromatics has been done without pre-re-forming units when using desulfurized feeds and special catalysts with very high coke resistance and under critical control of preheating temperatures and heat flux profiles on the re-forming reactor.79

2.1.2.4.Catalytic Promoter Effects.As in the case of methane steam re-forming,catalysts used in liquid fuel steam re-forming are mainly based on nickel.Noble metals(Ru, Rh)are more effective than Ni,because of their higher intrinsic rates for the activation of C-C and C-H bonds, and less susceptible to carbon formation,but are more expensive.Two strategies are employed in the formulations of catalysts to re-form liquid fuels in order to decrease carbon deposits on the catalyst:(i)the enhancement of water adsorption on catalysts and(ii)the modification of active

https://www.wendangku.net/doc/b517376073.html,position of Logistic Fuels a

gasoline diesel grade2jet-A

paraffins(%vol)455560

oleffins(%vol)822

napthenes(%vol)121620

aromatics(%vol)352718

sulfur(wt%)0.0050.005

a From Astarita et al.and Naidja et al.71,72

CO+3H2f CH4+H2O?H°298K)-206.2kJ/mol

(8)

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metal surfaces via the presence of other metals.Enhanced water adsorption can be achieved using carefully engineered supports with the addition of alkali,especially potassium, or magnesium oxides.The improved resistance to carbon formation on alkali and magnesium supports is caused by an increase in the rate of dissociation of water on the supports.As a result,the amount of OH species present on active metal surfaces is increased,thereby enhancing the removal of CH x and delaying the full dehydrogenation of CH x species of the atomic C precursor of carbon deposition on metal surfaces.Supports of the types mentioned above have been used in industrial naphtha steam re-forming catalysts.82The addition of lanthanides to supports also improves the stability of re-forming catalysts and decreases carbon formation during steam re-forming of higher hydrocarbons.83-85Wang and Gorte84investigated the effect of cerium oxide as the promoter of noble metal catalysts for the steam re-forming of various hydrocarbons.Cerium promotion revealed a beneficial effect by both decreasing the rate of carbon deposition and increasing the catalytic activity.Ozkan et al.83reported that the presence of lan-thanide elements(La,Ce,and Yb)significantly enhances catalytic activity and stability,due in part to the fact that lanthanides help to inhibit both the growth of nickel crystallites and the carbon deposition on catalyst surfaces. Studies carried out at the Argonne National Laboratory (ANL)have shown that group8,9,and10metals dispersed on doped ceria supports are active catalysts for re-forming of a wide range of hydrocarbons,including gasoline and diesel.86,87The improvement in the catalytic performance of catalysts with regard to their resistance to coke deposition has been attributed to the high oxygen mobility associated with CeO2,which facilitates coke gasification.88,89 Another approach to minimizing carbon formation on catalysts is by modifying the Ni phases.The addition of Co,90 Mo,W,91Re,92Sr,93and Sn94to Ni catalysts has been shown to increase coking resistance under steam re-forming condi-tions.It was suggested that the major carbon-preventing effect of these promoters is to block the steps sites on Ni particles and hence remove the nucleation sites for graphite formation.95,96

Recently there has been increasing interest of investigation in noble metal-based catalysts(Ru,Rh,and Pd),despite their cost,because they exhibit the highest intrinsic rates for steam re-forming and prevent carbon deposition.The rate of carbon formation was found to be far less on noble metals than on Ni.29This result has been explained by the fact that the noble metals do not dissolve carbon.30Some patents and literature papers have reported on the application of supported Rh or Ru in the steam re-forming of high aliphatic hydrocarbons or of naphtha97,98A Ru-based(Ru/Al2O3)catalyst has been used for steam re-forming of hydrocarbons while preventing carbon deposition.97,98Suzuki et al.98have successfully conducted long-term(8000h)tests of steam re-forming of desulfurized kerosene using Ru/Al2O3-CeO2catalysts. 2.1.2.5.Catalytic Pre-re-forming.The problem of carbon formation may be solved through adiabatic pre-re-forming prior to the primary re-former.In the pre-re-former all high hydrocarbons are converted directly into C1components (methane and carbon oxides)in the low-temperature range, typically from673to823K.99The products from the pre-re-former can be heated to temperatures up to1073K, reducing the risk of carbon formation from thermal cracking of the fuel before it reaches the re-forming catalyst bed.100 Carbon formation is the most critical parameter for selecting operating conditions for pre-re-forming.The steam-to-carbon ratio and operating temperatures depend on the feedstock. Heavier feeds require higher steam-to-carbon ratio and higher operating temperature101(Table2).The pre-re-forming catalyst is especially prone to carbon deactivation due to the low operating temperature.Specially precipitated high nickel-loaded catalysts(Ni)20-30wt%)with supports with alkaline properties(MgO)60-70wt%)and high surface area are used in the pre-re-forming process.Catalysts based on noble metals have also been used for the pre-re-forming of heavy hydrocarbon feeds such as kerosene and diesel.101 The low operating temperature also requires catalysts with high resistance to sulfur poisoning.Sulfur poisoning on Ni catalysts varies with temperature,the effect of sulfur poison-ing being more important at lower temperatures.76Taking into account the difficulty involved in removing the organic S compounds present in fuels(derivatives of diben-zothiophene)through the conventional hydrodesulfurization process,sulfur must be removed using deep hydrodesulfu-rization with novel hydrotreating catalysts or by deep adsorptive desulfurization.78

2.1.2.6.Steam Re-forming in Supercritical Water.A novel noncatalytic re-forming process using supercritical water has been described.102In this process,supercritical water works both as a highly energized re-forming agent and as an extraordinary solvent.The process has been tested for a number of hydrocarbon fuels including diesel and jet fuel. The original efforts were targeted at converting JP-8fuel into hydrogen that could be used directly in PEM fuel cells, and preliminary results show that there is excellent potential for this process in more generally applicable on-site produc-

Figure 6.Steam re-forming activity and coking tendency of different hydrocarbons.Adapted with permission from ref23. Copyright1997Elsevier B.V.Table2.Operating Conditions for Adiabatic Pre-re-forming a

naphtha diesel jet-A inlet temperature(K)723753753 H2O/C ratio(mol/mol) 1.55 2.45 2.40 relative deactivation rate0.28 2.2 1.2

a Adapted from Christiansen.101

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tion of hydrogen from a variety of hydrocarbon and oxygen-ate feedstocks.In the supercritical region,water is an excellent solvent for oxygen and hydrocarbons,excluding hydrogen.103,104As a consequence of this high solubility the re-forming reactions are homogeneous,and hence no catalyst is required.Thus,hydrocarbon molecules are directly re-formed by water according to eq 1.

In the supercritical water re-formation process there is virtually no equilibrium limitation due to the insolubility of hydrogen,which maintains hydrogen concentration in the reaction mixture below the ultimate chemical equilibrium of the reaction.The large amounts of CO produced according to eq 1are further converted to additional hydrogen via the water gas shift reaction.A side reaction that takes place simultaneously in the re-formation process,regardless of being supercritical or not,is the pyrolysis of hydrocarbon (eq 9):

This pyrolysis reaction is largely responsible for the forma-tion of lighter hydrocarbons such as methane,ethane,and ethylene.It is irreversible under the reaction conditions and operates over a wide range of temperatures.As a result of repeated pyrolytic fragmentation,the resulting fragments become favorable for coking 103via cyclization processes.All hydrocarbons present in the diesel boiling range fraction and also polycyclic aromatic hydrocarbons of low polyaromaticity (number of cycles below 4)are completely soluble in supercritical water,thus allowing chemical reactions before coking takes place.

Supercritical water re-forming of JP-8fuel at 909K and 32.9MPa yields a very low proportion of carbon oxides (CO +CO 2)4.0mol %)and H 2(5.4mol %),whereas methane (64.4mol %)and ethane (30.8mol %)are the major reaction products.The lack of re-forming products shows that the temperature is too low to re-form the hydrocarbons present in the JP-8fraction into a syngas mixture.In contrast,a product gas composition containing up to 37.3mol %is obtained by supercritical water re-forming at 978K and 23.9MPa overall pressure.The reaction conditions and product selectivity employed in both cases are summarized in Table 3.It is likely that higher H 2yields can be achieved at somewhat higher temperature,although the experimental process device does not allow 978K to be surpassed.102

2.1.

3.Methanol

Methanol is industrially produced under high temperature and high pressure (523-573K,80-100bar),using a copper -zinc-based oxide catalyst developed by Imperial Chemical Industries Co.Methanol can be converted to a H 2-rich gas mixture by chemical or chemical -physical methods.In the next section,the steam re-forming reaction is

examined.Because decomposition of methanol in the absence of oxidant usually takes place,this reaction is first considered.2.1.3.1.Methanol Decomposition.Methanol decomposi-tion (eq 10)is an on-site source of H 2and CO for chemical processes and fuel cells.

The reaction is endothermic and can be performed on metals;group 10and 11metals of the periodic table are active for this reaction,among which Ni and Pd have been the most widely studied.These metals have been supported on different oxide substrates such as Al 2O 3,TiO 2,SiO 2,CeO 2,ZrO 2,and Pr 2O 3.105-116Palladium seems to be the most effective for methanol decomposition and,in the case of Pd supported on CeO 2,it has been observed that the decomposi-tion reaction of methanol on Pd catalysts depends on the metal crystallite size.116Usami et al.106tested a number of metal oxide-supported Pd catalysts and found that Pd/CeO 2,Pd/Pr 2O 3,and Pd/ZrO 2catalysts prepared by a coprecipitation procedure were active for the selective decomposition of methanol at temperatures below 523K.TOF values showed that CeO 2and Pr 2O 3systems are better candidates than ZrO 2for supporting palladium.As CeO 2and Pr 2O 3substrates are slightly reduced during activation,a strong metal -support interaction is developed,and as a consequence the C -O bond cleavage of CH 3OH becomes inhibited while the decomposi-tion reaction into CO and H 2prevails.Additionally,it was observed that the interaction of Pd and the support influences the performance of catalysts,in which smaller metal par-ticles 106and a stronger contact with the support are favorable for the decomposition reaction.For high metal loadings,a coprecipitation method is preferred in comparison with the impregnation procedure,which produces larger particles and lower interaction with the support.In carbon-supported platinum catalysts,the mechanism of CO adsorption has been shown to depend on the structure,117and the effect of the particle size has been reported as well when other supported transition metals,such as iron and/or copper,are tested in the methanol decomposition reaction.118

In addition,La 2O 3is a particularly attractive support because it allows high selectivity and specific activity in the methanol synthesis https://www.wendangku.net/doc/b517376073.html, 2O 3-modified palladium catalysts have been reported to be very active for the synthesis of methanol from (CO +H 2)mixtures.119As the reverse reaction of methanol synthesis from (CO +H 2)gas mixtures,the methanol decomposition reaction was also tested over a series of Pd/SiO 2catalysts promoted with lanthanum oxide.120In keeping with these ideas,La-modified Pd/CeO 2catalysts were prepared and tested in the reaction of methanol decomposition.121The addition of La 2O 3to a 2%Pd/CeO 2catalyst significantly improved the catalytic behavior,and a complete conversion of methanol can be achieved at around 548K,which in turn is nearly 40K lower than the temperature required for the 2%Pd/CeO 2catalyst.The TPR profiles reveal that the presence of La 2O 3shifts the reduction temperature of CeO 2to lower values,while at the same time hindering the reduction of PdO crystallites due to an accelerated diffusion of oxygen at the La 2O 3-CeO 2interface.A different effect has been found when noble metals are used as promoters of supported Pd catalysts.Kapoor et al.122found that 3%gold loading in a 4%Pd/CeO 2catalyst increases the conversion at 453K from 20to 40%.This effect is associated with the formation of the new

Table 3.Selectivity Data Obtained in Supercritical Water Re-forming of JP-8Fuel a product gas composition (mol %)pressure (MPa)T

(K)water

flow

rate (g/min)JP-8flow rate (g/min)H 2C 2H 4CO CO 2CH 4C 2H 632.990920.0 2.4 5.4 2.0 2.064.420.90.723.9

97820.70.3

37.317.18.030.0 2.3

0.0

a

Adapted from Lee et al.102

C x H y f C a H b +C c H d (x )a +c ;y )b +d )(9)

CH 3OH f CO +2H 2?H °298K )+90.1kJ/mol (10)

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Navarro et al.

active sites in Au-Pd bimetallic clusters,where both Au and Pd are involved in the reaction mechanism.

2.1.

3.2.Methanol Steam Re-forming.Currently,increas-ing attention is being paid to the low-temperature steam re-forming of methanol to produce high-purity hydrogen to be used as a fuel for on-board power generation in fuel cell vehicles.123The importance of methanol as a chemical carrier for hydrogen lies mainly in its ready availability,high-energy density,and easy storage and transportation.Among the reactions to be used for the production of hydrogen from methanol,the most widely applied one is the steam re-forming reaction(eq11):

A large variety of catalysts for steam re-forming of methanol including copper in their composition have been reported.124-131Commercial Cu/ZnO water gas shift and methanol synthesis catalysts127,128have been found to be active for the steam re-forming reaction.Shimokawabe et al.129have also described that highly active Cu/ZrO2can be

prepared by impregnation of a ZrO2substrate with aqueous solutions of the[Cu(NH3)4](NO3)2]complex,which proves to be more active than the corresponding Cu/SiO2catalysts. This particular interest of ZrO2as a substrate for the copper phases has led to the study of highly active Cu/ZrO2catalysts that have been prepared according to a variety of different methods,including impregnation of copper salts onto the ZrO2support,132-134precipitation of copper,132-137formation of amorphous aerogels,138,139microemulsion technique,140and CuZr alloys.141The central idea in all of these works is to maintain the zirconia support in the amorphous state under the calcination and reaction conditions in order to retain a high level of activity.The major drawback when zirconia crystallization is produced consists in the drop in both copper surface area and support specific surface.Additionally,a high copper-zirconia interfacial area must be maintained to prevent catalyst deactivation.Tetragonal zirconia can be stabilized by incorporation of aluminum,yttrium,and lan-thanum oxides,142thus preventing,or at least minimizing, its crystallization.

Breen and Ross143found that Cu/ZnO/ZrO2catalysts are active at temperatures as low as443K but that they deactivate severely at temperatures above590K.However, deactivation is inhibited upon incorporation of Al2O3.As stated above,the deactivation may be explained by consider-ing the transformation of amorphous zirconia into a crystal-line metastable tetragonal ZrO2phase.It has been shown that the temperature of crystallization of zirconia is reduced to a large extent in the presence of steam,142which accelerates crystal growth.The improvement of catalyst stability brought about by Al2O3incorporation comes from the increase in the temperature of crystallization of ZrO2,which remains amorphous at the reaction temperature.Furthermore,the incorporation of alumina increases both the copper and BET surface areas,increasing also the catalyst’s activity.

2.2.Catalytic Partial Oxidation

As stated above,steam re-forming is currently the most important industrial and economic process for the production of hydrogen from hydrocarbons.Nevertheless,steam re-forming is a very energy-intensive process,in which overheated steam in a H2O/HC molar ratio slightly higher than stoichiometric value is used to avoid carbon deposition. In this context,new processes for the production of H2from hydrocarbons,at lower energy costs,are needed.The partial oxidation processes(PO)are attractive alternatives because they avoid the need for large amounts of expensive super-heated steam.Partial oxidation technology,like steam re-forming,has a long history but attracted much less atention because supported metal catalysts rapidly become deactivated under typical reaction temperatures of about950K.After an intensive research period during the1980s,when the oxidative coupling of methane(OCM)was considered to be the future of natural gas conversion,several research groups noted that,under similar reaction conditions,some catalytic systems yielded large amounts of hydrogen,with no catalyst deactivation.45Since then,intensive work has been developed to address the mechanism of the reaction and the parameters necessary for obtaining a stable catalyst.

2.2.1.Methane

2.2.1.1.Reaction and Mechanisms.Partial oxidation of methane(POM)to synthesis gas is represented by eq12: The principle of catalytic partial oxidation is illustrated in Figure7.The POM reaction has been known from the 1990s,as described by York et al.in a recent review.144 Although great efforts have been made,the industrial application of POM is still limited,mainly owing to the requirement of an oxygen plant,145,146and as yet no clearly stable supported metal catalyst is available.This is a mildly exothermic reaction,and hence no external heating energy is required.Equilibrium calculations for the POM reaction revealed an increase in both conversion and CO+H2 selectivity with increasing temperature.In this sense,at atmospheric pressure and1073K,the equilibrium predicts a methane conversion of higher than90%and selectivity of close to100%(Figure8).According to stoichiometry of the reaction,the increase of pressure has a detrimental effect on the conversion.

CH3OH+H2O f CO2+3H2?H°298K)+49.4kJ/mol

(11)

Figure7.Illustration of the catalytic partial oxidation principle.

CH4+1/2O2f CO+2H2?H°298K)-35.6kJ/mol

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The active catalysts for POM are very similar to the supported metals used in SRM.They all are metals from groups 8,9,and 10(Ni,Co,Fe,Ru,Rh,Pd,Ir,Pt),among which supported nickel,cobalt,and noble metal catalysts (Ru,Rh,Pt)have been the systems most studied.Pyrochlore oxides (Ln 2Ru 2O 745),perovskite oxides (LaNiO 3,147LaNi x Fe 1-x O 3148),and hydrotalcite type materials (Ni -Mg -Al hydrotalcites 149-151)are other systems that have been used as catalyst precursors for POM reactions.

Two mechanisms have been proposed for the POM reaction:(i)the combustion and re-forming reactions mech-anism (CRR)152and (ii)the direct partial oxidation (DPO)mechanism.153-155In CRR,the methane is combusted in the first part of the catalytic bed,producing CO 2and H 2O.Along the rest of the bed,and after total oxygen conversion,the remaining methane is converted to CO +H 2by SMR and CO 2re-forming reactions.In DPO a CO +H 2mixture is produced directly from methane by recombination of CH x and O species at the surface of the catalysts.

Dissanayake et al.152validated the CRR mechanism in a Ni/Al 2O 3catalyst,obtaining an almost complete conversion of methane at temperatures higher than 973K,with a selectivity to CO +H 2of nearly 95%.Analysis of the different phases present in the catalytic bed leads to the conclusion that it is divided into three regions:the first,in contact with the CH 4/O 2reacting mixture,is a NiAl 2O 4spinel,of moderate activity for methane combustion;the second part is NiO/Al 2O 3,of high activity for methane combustion and where the total conversion of oxygen occurs;and,finally,the rest of the catalytic bed consists of Ni/Al 2O 3,which is active for SRM and CO 2re-forming.The distribu-tion of these different regions is temperature-dependent and is the reason for the observed changes in the behavior of the catalyst,which is activated in the presence of the reactive mixture at 1023K,maintains different degrees of activity when the temperature decreases to 773K,and deactivates at lower temperatures (Figure 9).

Besides these results confirming the CRR mechanism,the DPO mechanism is operative in other systems.Hickman and Schimdt 153-155found that the oxidation reaction of methane could be achieved in Pt and Rh monoliths under adiabatic conditions at very short residence times.In

this

Figure 8.Methane partial oxidation equilibrium:calculated CH 4conversion (a),CO selectivity (b),and H 2selectivity (c)at pressures of 1and 20atm for a 2:1CH 4:O 2molar feed.Symbols indicate experimental results using a Ni/Al 2O 3catalyst.Reprinted with permission from ref 4.Copyright 2005Imperial College Press.

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proposed mechanism,the CO +H 2gas is produced as primary product:

The reaction intermediates formed on the surface of the catalysts,and the way in which they participate in the reaction mechanism,are different,depending on the active metal,the support,and their interaction.Li et al.156have followed the surface state of Ni/Al 2O 3by a transient response technique;they concluded that if oxygen is the most abundant surface intermediate,the catalyst is not activr and that a catalyst in the reduced state,covered by adsorbed carbon,is essential for the activation of the reactants.This reduced state of the metal surface as a condition for the activation of the reactants has also been observed in Rh/Al 2O 3in TAP experiments,157because CH 4is adsorbed dissociatively on the metal and the pre-adsorbed oxygen reduces this activa-tion.Moreover,the degree of oxygen coverage changes the mechanism of reaction:from DPO at low oxygen coverage to CRR at high oxygen coverage.

2.2.1.2.Catalyst Deactivation and Promoter Effects.Because several supported catalytic systems have high activity for the POM reaction,the main topic of research is the stability of the catalysts.There are three main processes for the deactivation of the catalyst:carbon deposition,sintering of metal crystallites,and oxidation of metal atoms by oxygen or steam.Carbon deposition is due to the process of decomposition of CH 4(eq 5)and CO (eq 4).Two different kinds of carbon can be formed on the surface of the catalyst:encapsulated carbon,which covers the metal particle and is the reason for physical -chemical deactivation;

and whiskers of carbon,which do not deactivate the particle directly but may produce mechanical plugging of the reactor.The catalysts are promoted to reduce the extent of carbon formation.The improvement of the catalyst’s stability can be achieved using an appropiate support.In the design of catalysts for re-forming reactions,the influence of the support has been one of the issues most investigated.Tsipouriari et al.158compared Ni/Al 2O 3with Ni/La 2O 3and found that in the former system the deposition of carbon increases with the time on stream.In the lanthana-supported catalyst,carbon is also accumulated,but this carbon deposited on the surface is constant and does not increase with time.The same effect is detected on magnesia-supported catalysts due to the formation of a Mg 1-x Ni x O solid solution.159In contrast,the use of ZrO 2as a support is not effective,because metal particles become rapidly sintered due to the low Ni -ZrO 2surface interaction.The effect of the support has been also investigated in other metals,and the tendencies are not the same in all cases.Bitter et al.160found that the trend in stability on supported platinum follows the order ZrO 2>TiO 2>Al 2O 3.This trend is different in supported nickel,Al 2O 3-supported nickel being more stable than the corre-sponding TiO 2-supported catalyst.161In the case of Pt,there is no evidence of sintering,and deactivation is produced by blockage of the active centers by carbon.The support,in this case,plays a very active role for the reducible oxides (e.g.,TiO 2).In the Pt/TiO 2system,it is well-established that small TiO x moieties decorate the metal particles 162and may so allow the reaction of coke fomation to occur close to the metal,affecting adversely the reaction on the metal.Also,some differences are found in supported Ir catalysts,with an activity trend for the POM in the order TiO 2>ZrO 2>Y 2O 3>MgO >Al 2O 3>SiO 2.163In these systems,SRM does not change with the support,and the trends for POM and CO 2re-forming are the same.Therefore,a CRR mechanism can be concluded for these catalysts.On the Rh/Al 2O 3157system,water is adsorbed on the alumina surface,which plays the role of the oxygen source in the POM reaction.Also,in Ni and Ru supported in Al 2O 3,a similar effect is produced,due to the formation of hydroxyl groups at the surface of Al 2O 3that provide oxygen to the active metal sites.In contrast,when these metals are supported on SiO 2,the support does not participate in the reaction mechanism.

Improvements in catalyst stability can be achieved not only by the use of an appropriate support but also by doping the catalyst with other metals.In Ni/Al 2O 3,a beneficial effect of the addition of noble metals (Pt,Pd,Ru)has been described.164Nichio et al.165promoted Ni/Al 2O 3by adding a tin organometallic complex to the catalyst in the reduced state (metallic Ni).This procedure allows the collection of bimetallic Sn -Ni systems with a good interaction between metals and,at concentrations of Sn in the 0.01-0.05%range (Sn/Ni surf <0.5),the deposition of carbon upon reaction decreases with no appreciable change in the catalytic activity.The Sn causes breaking of the Ni ensembles,active for carbon deposition (this is a structure-sensitive reaction),165but is not enough to affect the active sites for POM.The most typical way to promote nickel catalysts is by the use of alkaline and alkaline earth metals.Chang et al.166explained the promotion with K and Ca of a Ni/NaZSM-5zeolite by the formation of carbonaceous species,produced by the interaction of CO 2with the promoters.In isotopic effect experiments,they also observed that the activation of CH 4

Figure 9.Schematic representation of Ni/Al 2O 3catalyst bed composition during catalytic partial oxidation of methane at various temperatures.Reprinted with permission from ref 152.Copyright 1991Elsevier B.V.

CH 4f C(ads)+4H(ads)(13a)C(ads)+[O]s f CO (ads)f CO

(13b)2H(ads)f H 2

(13c)

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at the nickel surface is not the rate-determining step in the DPO mechanism.The rate is determined by the reaction of O ads +C ads ,as previously shown by Schuurman et al.60in Al 2O 3-and SiO 2-supported Ni catalysts.The reduction of carbon deposition has been also successfully achieved in Ni/γ-Al 2O 3catalysts promoted with Li and La.167-169

2.2.2.Liquid Hydrocarbons

2.2.2.1.Reaction and Mechanisms.In recent years,the catalytic partial oxidation of high hydrocarbons employing very short reaction times (milliseconds)and high tempera-tures (1123-1273K)over noble metals supported on porous ceramic monoliths has been the subject of much re-search.154,155,170Catalytic partial oxidation of hydrocarbons is described by the idealized eq 14.

The oxygen-to-fuel ratio (n )determines the heat of reaction and the hydrogen yield.The direct catalytic partial oxidation reaction is much faster than the corresponding catalytic steam re-forming reaction by roughly 2orders of magnitude,but the H 2yield per carbon in the fuel is lower.Despite the simplicity of eq 14,the catalytic partial oxidation of liquid fuels is a complicated process in terms of the number of catalytic reactions involved.Partial oxidation commonly includes total oxidation,steam re-forming,CO 2re-forming,hydrocarbon cracking,methanation,and water gas shift.No detailed mechanism of hydrogen production from higher hydrocarbons has yet been established.A basic scheme 171assumes that the reaction is initiated near the catalyst entrance by complete dissociation of hydrocarbons due to multiple dehydrogenation and C -C cleavage reactions.This is followed by reaction of the absorbed oxygen with carbon and hydrogen to form CO,CO 2,and H 2O,which desorb along with H 2.Aromatics tend to be less reactive than n -alkanes in partial oxidation reactions.171They are strongly adsorbed to the metal sites,causing kinetic inhibition,and are also more prone to carbon formation than paraffins and cycloparafins.172The complexity of the process and the nature of liquid fuels,with hundreds of different components,have produced slow development at the industrial scale,the process still being in the exploratory stage.

2.2.2.2.Catalyst Deactivation and Promoter Effects.There are relatively few experimental studies on the catalytic partial oxidation of liquid fuels.Results on catalytic partial oxidation of n -hexane,173n -heptane,174n -octane,175iso-octane,171,173and mixtures simulating liquid fuels have shown that deactivation by both sulfur and carbon deposition are key challenges to the use of catalytic partial oxidation.Catalysts for partial oxidation of liquid fuels have been primarly based on nickel,175platinum,175,176rhodium,173,176,177and bimetallics.176Direct comparison among these catalysts is reported in only a few cases,rhodium generally being the most active and the most selective to hydrogen.173,176The advantage of rhodium is attributed to a lower tendency of surface H atoms to become oxidized to surface hydroxyl radicals,leading to the formation of water.As a result,desorption of the H atoms as H 2molecules is the favored process on rhodium.A recent work 178has reported the use of oxygen-ion conducting systems as supports of noble metals applied to partial oxidation of diesel fuels.The study shows that ceria and zirconia were found to be effective in minimizing carbon deposition,a mixed ceria -zirconia sup-

port being superior to either.The authors attributed this behavior to a temperature-dependent mechanism involving the dissociative adsorption of oxygen on the metal following its spillover to the support.

2.2.

3.Methanol

Among the different methods employed to produce hydrogen from methanol (decomposition,steam re-forming,and partial oxidation),selective production of H 2by partial oxidation has some obvious advantages,because it is an exothermic reaction and a higher reaction rate is expected,which shortens the reaction time to reach the working temperature from the cold start-up conditions.In this section,catalysts and promoters employed and the reaction mecha-nism are examined.

2.2.

3.1.Copper -Zinc Catalysts.Copper -zinc catalysts have been found to be very active for the partial oxidation of methanol 179(eq 15):

The partial oxidation reaction starts at temperatures as low

as 488K,and the rates of methanol and oxygen conversion increase strongly with temperature to selectively produce H 2and CO 2(Figure 10).The rate of CO formation is very low across the temperature range explored (473-498K),and H 2O formation decreases for temperatures above 488K.As a general rule,methanol conversion to H 2and CO 2increases with copper content,reaching a maximum with Cu 40Zn 60catalysts (40:60atomic percentage)and decreasing for higher copper loadings.The Cu 40Zn 60catalyst with the highest copper metal area has been found to be the most active and selective for the partial oxidation of methanol.Unreduced copper -zinc oxide catalysts display very low activity,mainly producing CO 2and H 2O and only traces of H 2,although the catalysts become eventually reduced under reaction condi-tions at high temperatures.From the reaction rates and copper areas,turnover frequency (TOF)values have been calculated as a function of copper content at constant temperature (497K).It was observed that both the apparent activation energy (E a )and the TOF were higher for the low copper content catalysts and then decreased slightly,tending to constant

C n H m +n /2O 2f n CO +m /2H 2

(14)

Figure 10.Partial oxidation of methanol over the catalyst Cu 40-Zn 60:(0)CH 3OH conversion;(+)O 2conversion;(O )H 2;(])CO 2;(4)H 2O;(3)CO.Reprinted with permission from ref 179.Copyright 1997Elsevier B.V.

CH 3OH +1/2O 2f CO 2+2H 2

?H °298K )-192.2kJ/mol (15)

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value at Cu loadings above 50%(atomic).The simultaneous variation of E a and TOF suggests that the enhancement in reactivity would be a consequence of a change in the nature of the active sites rather than induced by a simple spillover type synergy.Activity data for the methanol partial oxidation reaction to hydrogen and carbon dioxide over Cu/ZnO catalysts obtained with different catalyst compositions and different Cu 0metal surface areas have shown that the reaction depends on the presence of both phases:ZnO and Cu 0.Additionally,Wang et al.180found that the presence of ZnO in silica-supported Cu catalysts allows a higher dispersion of metallic copper,although a high concentration of zinc gives Cu 2O crystallites.On the other hand,for Cu -Zn catalysts,with Cu concentrations in the 40-60wt %range,the copper metal surface area seems to be the main factor determining the reaction rate.181

The O 2/CH 3OH molar ratio in the feed has a strong influence on catalyst performance.As illustrated in Figure 11,CH 3OH conversion rates and H 2and CO 2selectivities increase almost linearly for O 2partial pressures in the range of 0.026-0.055bar (O 2/CH 3OH ratios )0.03-0.063).182A further increase in O 2partial pressure leads to a sharp drop in CH 3OH conversion and an almost complete inhibition of H 2formation,with the simultaneous production of H 2O and CO 2.When lower O 2partial pressures are returned to,the conversion and selectivity to H 2and CO 2remain constant and at very low values,producing a hysteresis curve.As revealed by X-ray diffraction patterns,a thick layer of copper oxide grows on the surface of copper crystallites when exposed to O 2pressures above 0.055bar.Thus,it is inferred that Cu +sites appear to be responsible for the partial oxidation reaction of methanol.Cu 0metal has low reactivity to methanol,and activity is optimized at intermediate surface coverages by oxygen.

TPD experiments with pure Cu 0,pure ZnO,and the Cu/ZnO catalyst show that methanol can be activated by both ZnO and copper.182On the ZnO surface,methanol may form intermediates,which in the presence of copper might react and desorb more easily,probably via a reverse spillover process.Isotopic product distribution of H 2,HD,D 2,H 2O,HDO,and D 2O in the temperature-programmed reaction of CH 3OD shows a slight enrichment in products with H,suggesting that during methanol activation on the ZnO some of the D atoms might be retained by the support.182CH 3OH activation via O -H bond cleavage occurs easily on group 8,9,and 10metals at temperatures as low as 100-200K.183Nevertheless,CH 3OH bond activation on copper catalysts requires higher temperatures or the presence of oxygen atoms

on the copper surface.It has been proposed that the basic character of O ads atoms on copper surfaces would facilitate H-transfer from the O -H bond to form a surface methoxy intermediate.184The kinetic isotope effect (k H /k D ) 1.5)observed for CH 3OH conversion 182can be related to this H-transfer,suggesting that during the CH 3OH oxidation O -H bond cleavage is at least partially involved in the rate-determining step,especially for the water yield with an isotopic effect of k H /k D )2.0.However,for H 2formation (k H /k D )0.9),the rate-determining step is related to C -H bond activation,because the C -O bond does not break during the reaction (no CH 4formation is observed).These kinetic results obtained for the partial oxidation reaction on Cu/ZnO catalysts are in agreement with the data found for the decomposition and steam re-forming reactions of metha-nol.For these reactions,it has been suggested that a methoxide species would be rapidly formed and that the rate-determining step would be the cleavage of the C -H bond to form the H 2CO species.181,182,184-190

It has been suggested that oxygen atoms participate in methanol activation through the abstraction of the hydroxyl H atom to form methoxide and OH surf .This OH surf species rapidly loses H to the surface,regenerating the O surface species.182Although all of these reactions occur on the copper surface,ZnO also plays some role in the reaction.The results of TPD experiments carried out after the pre-adsorption of the O 2/CH 3OH mixture on pure ZnO are conclusive in the sense that CH 3OH is partly converted into H 2,CO,CO 2,and H 2CO.182Of the two peaks observed in the TPD profiles,the one at low temperature (573K)for H 2and CO 2suggests the participation of bulk oxygen,whereas that seen at a slightly higher temperature (590K)is related to the formation of H 2CO.As stated above,the Cu metal area determines the reaction rate,but the combination of copper with a certain amount of ZnO seems to be of fundamental importance for the partial oxidation reaction.Thus,ZnO might also partici-pate in methanol activation and,through a reverse spillover effect,transfer species to the metallic surface for further reaction.

The incorporation of small amounts of Al 2O 3(up to 15%Al at.)to the Cu/ZnO system results in lower activity,indicating that aluminum has an inhibiting effect on the partial oxidation of methanol.177For the Cu 40Zn 55Al 5catalyst,this inhibition is clear at lower temperatures,although the activity approaches that of the Al-free Cu 40Zn 60counterpart at temperatures close to 500K.Other catalysts with higher Al loadings (Cu 40Zn 50Al 10and Cu 40Zn 45Al 15)do not show significant activity in the temperature range studied.177In terms of stability,the behavior of Cu 40Zn 60and Cu 40Zn 55-Al 5catalysts is very different:whereas the Cu 40Zn 60catalyst loses 43%of activity,with a less marked drop in the selectivity of H 2and CO 2,after 110h of on-stream operation at 503K,no significant deactivation is observed for the Cu 40-Zn 55Al 5catalyst.The addition of aluminum as Al 2O 3to the Cu -ZnO favors the dispersion of the copper phase and improves catalyst stability by preventing the sintering of metal particles.This stabilization effect due to the presence of aluminum is,in this way,very similar to the one observed for the steam re-forming of methanol.191

For both binary Cu -ZnO and ternary Cu -ZnO(Al)systems,reduction pretreatments control the structural and morphological characteristics of the catalyst surface.192These initial characteristics play a central role in the evolution of the oxidation state and structural morphology during the

Figure 11.Effect of O 2partial pressure on CH 3OH conversion in the reaction with the Cu 40Zn 60catalyst at 488K.Reprinted with permission from ref 182.Copyright 2003Springer.

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reaction,because the dynamic behavior of the catalyst surface is determined by the conditions of the gas atmosphere during the reaction.The temperature dependence of CH 3OH conver-sion on a Cu 55Zn 40Al 5catalyst in its oxidized,reduced,and air-exposed pre-reduced states during the partial oxidation reaction in an O 2/CH 3OH )0.3(molar)mixture is shown in Figure 12.192All conversion profiles display a sigmoidal-like shape,with a marked increase in CH 3OH conversion within a narrow temperature range.The reaction starts at 416K on the reduced sample,whereas this point shifts to 422and 434K in the air-exposed and oxidized samples,respectively.Conversely,however,product selectivity is the same in all cases.For a CH 3OH conversion of around 0.6,where oxygen is completely consumed,the slope of the curves changes as a consequence of the overlapping of the decomposition reaction.From the data in Figure 11it is clear that the oxidized sample becomes reduced during the partial oxidation reaction,and this reduction process leads to surface reconstruction with a higher CH 3OH decomposition capacity than that of the pre-reduced counterparts.These differences are related to changes in the number,but not the character-istics,of the active sites induced by the different reduction potentials of the reacting gases.

2.2.

3.2.Palladium Catalysts.Group 10metals,and more specifically palladium,are highly active in the partial oxidation reaction.193,194High yields to H 2have been obtained on pre-reduced Pd/ZnO catalyst under O 2/CH 3OH feed ratios of 0.3and 0.5.For the 1wt %Pd/ZnO catalyst,CH 3OH conversion reaches 40-80%within the 503-543K tem-perature range.Upon increase of the reaction temperature,CH 3OH conversion increases,with a simultaneous increase in H 2selectivity at the expense of water.Because the oxygen is completely consumed,this selectivity trend suggests some contribution of the methanol steam re-forming produced by the water byproduct.Important structural changes take place at the Pd -ZnO interface during on-stream operation.With X-ray diffraction,temperature-programmed reduction,and

X-ray photoelectron spectroscopy techniques,a PdZn alloyed phase was seen.193,195The formation of this alloy has been also detected in used Pd/ZnO catalysts prepared according to different methods (microemulsion and impregnation)196and in Pd/ZnO catalysts used in the steam re-forming of methanol.197The reactivity of the PdZn alloy is somewhat different from that of small Pd clusters,as illustrated by the behavior of a 5wt %Pd/ZnO catalyst,which exhibited fairly high selectivity to HCHO and CO and where PdZn alloy is formed to a larger extent than in 1wt %Pd catalyst.It is likely that processes such as CH 3OH decomposition,the inability to oxidize the intermediate HCHO,and the low oxidation rate of CO would be involved in large PdZn alloy particles,whereas the H 2selectivity is favored in small Pd and PdZn alloy clusters.Pd/ZnO catalysts prepared by the microemulsion method also show higher CO yield when Pd particle size is larger.196

The nature of the support to a large extent determines the performance of supported catalysts.Thus,the 1wt %Pd/ZrO 2catalyst exhibits not only oxidation products (H 2and CO 2),as happens on the parent Cu -ZnO catalysts,but also the decomposition reaction seems to occur to a greater extent.194

2.3.Autothermal Re-forming

Hydrogen production using autothermal reforming (ATR)has recently attracted considerable attention due to its high energy efficiency with low investment cost due to its simple system design.The ATR process has been used to produce hydrogen-and carbon monoxide-rich synthesis gas for decades.In ATR the heat for the re-forming reactions is supplied by internal combustion.Consequently,there is no need to supply heat to the reactor over and above the amount provided in the preheating of the reactants.The overall chemical reactions taking place in the ATR include partial oxidation (eq 14),steam re-forming (eq 1),and water gas shift (eq 2).

The main advantages of the use of the autothermal process with respect to the steam re-forming process are related to economics of scale;much larger single-stream units are possible with adiabatic ATR than with steam re-forming,and the size of equipment is smaller,because ATRs are very compact units compared to steam re-formers.Furthemore,re-former tube materials limit the outlet temperature from steam re-formers to a maximum of about 1223K,whereas autothermal processes easily exceed 1273K.This makes higher conversion of the feed possible,even at low steam-to-carbon ratios.The main disadvantage of ATR,especially with oxygen as oxidant,is that it requires an oxygen source.Oxygen plants are expensive,and the associated investments constitute the major part of the total investments.

2.3.1Methane

The overall chemical reactions taking place in the ATR reactor are partial oxidation,steam re-forming,and water gas shift.The ATR reactor operates in three zones:(i)combustion zone,(ii)thermal zone,and (iii)catalytic zone (Figure 13).The combustion zone is a turbulent diffusion flame where CH 4and oxygen are gradually mixed and https://www.wendangku.net/doc/b517376073.html,bustion in ATR is substoichiometric with an overall oxygen to hydrocarbon ratio of 0.55-0.60.Typically,the ATR operates at high temperatures of ca.2200K in the combustion zone.In the thermal zone above the catalyst bed further conversion occurs by homogeneous gas-

Figure 12.Temperature dependence of CH 3OH conversion during temperature-programmed start-up over the Cu/ZnO/Al 2O 3catalyst in different initial states:(O )oxidized;(b )reduced;(9)reduced +air exposed.Atmospheric pressure,feed ratio O 2/CH 3OH )0.3,heating rate )0.1K/min.Reprinted with permission from ref 192.Copyright 2002Elsevier B.V.

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phase reactions.The main reactions in this zone are the homogeneous gas-phase steam methane re-forming and shift reaction.In the catalytic zone the final conversion of hydrocarbons takes place through heterogeneous catalytic reactions at 1200-1400K including methane steam re-forming and shift reactions.The H 2/CO ratio at the outlet of the reactor can be precisely adjusted by varying the H 2O/CH 4and/or O 2/CH 4molar ratios in the feed.

As ATR is a combination of homogeneous partial oxida-tion with catalytic steam re-forming,the active catalysts used are the same as those for the steam process,namely,the group 8,9,and 10metals,especially Ni,Pt,Pd,Rh,Ru,and Ir.However,the high temperature of operation requires catalysts with a high thermal stability.The preferred catalyst for ATR is a low loaded nickel-based catalyst supported on alumina (R -Al 2O 3)and magnesium alumina spinel (MgAl 2O 4).Spinel has a higher melting point and in general a higher thermal strength and stability than the alumina-based catalyst.Recent studies 198also propose the use of a temperature-stable support for nickel phases,consisting of a low surface area macroporous zirconia -haffnia carrier that shows excellent resistance to high-temperature treatments.Alternative catalyst formulations for methane ATR based on bimetallics have been studied because the activity of nickel catalysts can be increased by the addition of low contents of noble metals (Pt,Pd,Ir).These findings have stimulated the study of several bimetallic nickel catalysts.Ni -Pt bimetallic catalysts show higher activity during ATR than separate nickel and platinum catalysts blended in the same bed,although the real mechanism for this increase in activity is not clear.Explana-tions advanced includd (i)the increase in the reducibility of Ni due to the formation of an alloy or hydrogen spillover 199and (ii)the increase in exposed Ni surface area under reaction conditions assisted by the noble metal.200

2.3.2.Liquid Hydrocarbons

As for methane,the overall reactions taking place in the ATR reactor include partial oxidation (n )1in eq 14),steam re-forming (eq 1),and water gas shift (eq 2).For liquid fuels,ATR conditions have been achieved using a re-former

including a partial oxidation zone and a separate steam re-forming zone.The oxygen-to-carbon (O/C)and the steam-to-carbon (S/C)ratios determine the energy released or absorbed by the reaction and define the adiabatic temperature and consequently the concentration of H 2in the fuel gas.201Higher H 2O/C ratios reduce the CO yield with lower equilibrium temperature.202In the ATR of diesel fuel,thermodynamic equilibrium can be achieved at a H 2O/C ratio of 1.25,an O 2/C ratio of 1,and an operating temperature of 973K.

The operating conditions in ATR process require catalysts and supports with high resistance to thermally induced deactivation.Coking can be controlled with excess steam (and/or oxygen injection),whereas the low sulfur coverage on catalysts at the elevated temperatures of ATR makes desulfurization prior to ATR not necessary.

Noble metal catalysts (Pt,Rh,and Ru)modified with promoters with high oxygen storage capacity (CeO 2-ZrO 2,CeO 2,CeGdO 2)have exhibited excellent re-forming activity,with good thermal stability and sulfur tolerance in the ATR of liquid fuels.203-209In recent years,research into catalysts for the ATR of hydrocarbons has paid considerable attention to systems with a perovskite structure of general formula ABO 3.210-212Perovskite oxides (ABO 3)are strong candidates as precursors of re-forming catalysts due to the possibility of obtaining well-dispersed and stable active metal particles on a matrix composed of metal oxides that may allow the small particles of the metal to be stabilized in position B under the reaction conditions.Investigation into the applica-tion of non-precious group metal-based catalysts for ATR of high hydrocarbons has attracted some attention in the past few years.The use of group 6metal carbides in re-forming a range of high hydrocarbons was successfully demon-strated.212-214In contrast with noble metal-and nickel-based catalysts,bulk molybdenum carbide shows stable perfor-mance in the ATR of higher hydrocarbons,such as gasoline and diesel,performed under much lower steam/carbon ratios.

2.3.3.Methanol

An even more appealing option than steam re-forming (eq 11)and partial oxidation (eq 15)is to combine these two reactions,providing the possibility of producing hydrogen under almost autothermal conditions (eq 16):181,215-219

Copper-based catalysts also display good performance in ATR.Agrell et al.,219using a Cu -ZnO catalyst,reported that,at differential O 2conversions,water is produced by combustion of methanol.When oxygen conversion is com-plete,water production levels off and H 2formation is initiated.Then,CH 3OH conversion and H 2and CO selectivity increase,whereas water selectivity decreases.If ZrO 2and Al 2O 3are incorporated to the Cu -ZnO catalyst,the resulting catalyst exhibits the best performance for steam re-forming,although the light-off temperature for the partial oxidation reaction is lower for the Cu -Zn binary catalyst.CO formation over these ZrO 2-loaded Cu -ZnO catalysts is less pronounced than in the other catalysts and still lower than in the steam reaction.Purnama et al.220also found this beneficial effect of the oxygen addition to the feed during steam re-forming of methanol on Cu/ZrO 2catalysts.

Figure 13.Illustration of an ATR reactor.

CH 3OH +(1-2n )H 2O +n O 2f CO 2+(3-2n )H 2

(0

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The oxidative methanol re-forming reactions of methanol have also been investigated over Cu-ZnO(Al)catalysts derived from hydrotalcite-like precursors.190,218,221The oxy-re-forming reactions under O2/CH3OH/H2O)0.3:1:1molar ratios in the feed lead to high activity for CH3OH conversion and very high selectivity for H2production.All of the catalysts exhibit higher CH3OH conversions than that attained under the conditions of the partial oxidation process.Another interesting result is that CO levels at the exit stream are much lower than in the case of the reaction performed under the conditions of partial oxidation reaction.Despite the complex-ity of the mechanism of the oxy-re-forming of methanol,it is likely that the water gas shift reaction may contribute to the reduction in CO selectivity at the expense of water.

2.4.Gasification of Coal and Heavy Hydrocarbons

Gasification is another choice technology for the large-scale production of hydrogen.Gasification involves the reaction at high temperatures(1200-1400K)and moderate pressures(5-10bar)of a source of carbon,associated or not with hydrogen,with a source of hydrogen,usually steam, and/or oxygen to yield a gas product that contains CO,H2, CO2,CH4,and N2in various proportions.Proportions of these component gases depend on the ratio of the reactants used and on the reaction conditions.It is a versatile process that can use all carbon-based feedstocks,including coal,petro-leum residues,biomass,and municipal wastes,and is the only advanced power generation technology for coproducing a wide variety of commodity products to meet market needs. Gasification-based systems are the most efficient and envi-ronmentally friendly alternatives for the production of low-cost electricity and other useful products and can be coupled to CO2concentration and sequestration technologies.222 The first companies to convert coal to combustible gas through gasification were chartered in1912.During the 1930s,the first commercial coal gasification plants were constructed,followed by town gas applications in the1940s. In the1950s,chemical process industries started applying gasification for hydrogen production.At present,gasification is a commercially proven mature technology with about40 GW total syngas production capacity around the world.223 2.4.1.Chemistry

The chemistry of gasification is quite complex,involving cracking,partial oxidation,steam gasification,water gas shift, and methanation.In the first stages of the gasification,the feedstock becomes progressively devolatilized upon increas-ing temperature and yielding simultaneously oils,phenols, tars,and light hydrocarbon gases224-229followed by the water gas shift reaction230,231and methanation reactions.In a simple form,the basic reaction network in an oxygen and steam fed gasifier can essentially be summarized as follows:

Partial combustion predominates at high temperatures,

whereas total combustion predominates at lower tempera-

tures.The water gas shift reaction alters the H2/CO ratio but

does not modify to a significant extent the heating value of

the syngas mixture.Methane formation is favored under high

pressures(above8bar)and low temperatures(about1100

K),and therefore its formation plays a major role in lower

temperature gasifiers.The rates and degrees of conversion

for the various reactions involved in gasification are functions

of temperature,pressure,and the nature of the hydrocarbon

feed being gasified.At higher operating temperatures,the

conversion of hydrocarbons to CO and H2increases,whereas the production of methane,water,and CO2decreases.

Depending on the gasification technology,significant amounts

of CO2,CH4,and H2O can be present in the synthesis gas

as well as trace amounts of other components.232Under

reducing conditions of the gasifier,most of the organic sulfur

is converted to hydrogen sulfide(H2S),whereas a small

fraction,usually not surpassing10%,forms carbonyl sulfide

(COS).The nitrogen present in organic heterostructures forms

ammonia(NH3)and smaller amounts of hydrogen cyanide

(HCN).Most of the chlorine present in the fuel reacts with

hydrogen to form hydrogen chloride and some particulate-

phase inorganic chloride.Trace elements usually associated

with inorganic matter,such as mercury and arsenic,are

released during gasification and partitioned between the gas

phase and ash fraction.The formation of a given species

and its partition between the gas phase and solid phase

depend strongly on the operating conditions and gasifier

design.

Several metals and metal oxides catalyze the reactions

involved in gasification and may,therefore,modify the values

of their kinetic constants.For example,several authors233-235 have found how iron-based species(Fe2O3,Fe3O4)affect the

rate of the overall steam gasification of coal and/or biomass.

Reactions17c,17e,and17f are also catalyzed by nickel.232, 236Calcium-based catalysts are also known to promote steam gasification under moderate reaction conditions.High-

temperature X-ray diffraction studies have demonstrated that

the addition of calcium decreases the reaction temperature

and increases the gasification rates.237Balasubramanian et

al.238found that the addition of NiO/Al2O3and CaO catalysts

successfully achieved near equilibrium conditions for re-

forming of CH4,water gas shift,and the separation of CO2

simultaneously in a single reactor at823K.

2.4.2.Gasification with Simultaneous CO2Capture

The in situ capture of CO2during gasification is an

especially attractive process because it allows very high H2

content with very low(near zero)CO2and tar contents in

fast pyrolysis:

C n H m O y f tar+H2+CO2+CH4+C2H4+...

(17a) steam re-forming:

tar+x H2O f x CO+y H2(17b)CO

2

re-forming:

tar+CO2f x CO+y H2(17c) partial oxidation:

C

n

H m+n/2O2f n CO+m/2H2(17d) WGS:

CO+H2O f CO2+H2(17e) methanation:

CO+3H2f CH4+2H2O(17f)

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the gasification gas.226,239Attempts to use CaO in a CO2 acceptor process were first conducted by Curran et al.240and McCoy et al.241In these studies only half of CO and CO2 was immobilized in CaO.A new method that combines the gas production and separation reactions(hydrogen production by reactions integrated gasification,HyPr-Ring)in a single reactor was proposed by Lin et al.242In this process,the energy required for the endothermic re-forming reactions is supplied by the heat of CO2absorption.Wang and Takara-da243reported complete fixation of CO2with Ca(OH)2for a Ca/molar ratio of0.6(stoichiometry dictates the ratio to be 1)along with enhanced decomposition of tar and char.In addition,the overall conversion rate of CO to CO2can be enhanced by the inclusion of an oxygen donor in the reaction zone.The steam re-forming rate of CH4and other light

hydrocarbons released during coal pyrolysis may also be enhanced by incorporation of a suitable oxygen donor. Thermodynamic calculations also show that the enthalpy of the Fe2+/Fe3+oxide system is suitable for the water gas shift reaction,a necessary reaction required to convert the CO+ H2mixture to additional hydrogen(eq17e).However,Fe2O3 oxidizes H2at a rate2-10times higher as compared to CO.243This unwanted reaction results in a reduction in the yield of H2.

Mondal et al.235reported that selection of Fe2O3and CaO as the oxygen transfer compound and CO2removal material, respectively,provides additional benefits in H2production by gasification.The net result of these reactions is exother-mic,so additional CO2and H2are produced by CH4 re-forming.Then,the reduced FeO is regenerated in an air (or O2)stream and the heat released from this exothermic reaction is used to regenerate the carbonated CaO.Thus,the products would result into three separate streams:(i)high-purity H2for use in fuel cells;(ii)sequestration-ready CO2; and(iii)high-temperature oxygen-depleted air for use in gas turbines.The following are the reactions involved in the process,for which the heats of reaction are reported at1073 K.235

The efficacy of the simultaneous gasification-hydrogen enrichment process can be demonstrated by using a fluid bed reactor configuration.235Under typical reaction condi-tions,that is,temperature of1143K and85%steam,the incorporation of both CaO and Fe2O3[CaO/FeO2O3)2:1 (wt)]yields a gas with the highest H2purity along with maximum coal conversion.The use of CaO alone increases the H2yield and purity,whereas incorporation of Fe2O3alone has a negative effect on the H2yield.

https://www.wendangku.net/doc/b517376073.html,mercialization Status of Fuel Re-formers The H2demand for chemical processing in the United States increased from about23M Nm3in1996to about38 M Nm3in2000.A similar growth in H2consumption was observed for electronics,food-processing,and metal-manufacturing markets.244As stated above in this section, steam methane re-forming,coal and residues gasification, and methanol decomposition processes are mature technolo-gies for H2production.However,as long as natural gas(or CH4)remains at low or even moderate cost,SMR will continue to be the technology of choice for massive H2 production.This trend is expected to continue due to the rapidly growing interest in fuel cells(FCs)in stationary and mobile applications.Accordingly,distributed hydrogen pro-duction via small-scale re-forming at refueling stations could be an attractive near-to mid-term option for supplying hydrogen to vehicles.A brief account of the present status and/or commercialization of H2production technologies based in fossil precursors is summarized in the next sections.

2.5.1.Steam Methane Re-formers

2.5.1.1.Conventional Steam Methane Re-formers. Steam methane re-formers have been built over a wide range of sizes.For large ammonia,refining,and methanol plants (0.5×106Nm3/day),capital costs(including the re-former, shift reactor,and PSA unit)are about$200/kW H2output, and these decrease to about$80/kW H2for a5×106Nm3/ day plant.On the contrary,scale economics in the capital cost is increased up to about$4000/kW H2for small2300 Nm3/day plants.This technology can be,in principle,used for other applications which require much lower H2produc-tion rates such as that required for hydrogen refuelling station applications.However,the large size of standard re-former tubes(12m long)and high cost,due to costly alloy materials for high-temperature and high-pressure operation,make then unsuited for small-size re-formers.For these reasons,hy-drogen needs for FC technology and other niche applications require more compact,lower cost re-formers.245 methanation:C+2H2f CH4?H1073K

)+21.7kJ/mol(18i) carbon oxidation:C+Fe2O3f CO+2FeO?H1073K

)+9.4kJ/mol(18j) H2oxidation:H2+Fe2O3f H2O+2FeO?H1073K

)+29.0kJ/mol(18k) Oxide Regeneration Stage

decomposition:CaCO3f CaO+CO2

?H1073K)+167.6kJ/mol(18l) oxidation:FeO+O2f Fe2O3?H1073K

)-281.4kJ/mol(18m)

Hydrogen Enrichment Stage

coal gasification:C+H2O f CO+H2?H1073K

)+135.7kJ/mol(18a)

steam reforming:CH4+H2O f CO+3H2?H1073K

)+206.0kJ/mol(18b)

water gas shift:CO+H2O f CO2+H2?H1073K

)-33.1kJ/mol(18c)

Boudouard reaction:2CO f CO2+C?H1073K

)-169.4kJ/mol(18d)

CO oxidation:CO+Fe2O3f CO2+2FeO?H1073K

)-4.8kJ/mol(18e)

CO2sorption:CaO+CO2f CaCO3?H1073K

)-167.6kJ/mol(18f)

Hydrogen Enrichment Stage

CaO hydration:CaO+H2O f Ca(OH)2?H1073K

)-94.1kJ/mol(18g)

dry re-forming:CH4+CO2f2CO2+2H2?H1073K

)+260.8kJ/mol(18h)

Hydrogen Production Reactions from Carbon Feedstocks Chemical Reviews,2007,Vol.107,No.103969

https://www.wendangku.net/doc/b517376073.html,pact Annular Catalyst Bed Re-formers.For small sizes,a more cost-effective approach is to use a low-temperature,lower pressure re-former,with lower cost components.Steam methane re-formers for FCs in the range of0.4-3kW have been developed and have also been recently adapted for stand-alone H2production.In these designs,the re-former operates at lower temperature and pressure(3bar,970K),which facilitates materials avail-ability and cost.Estimate costs for small FC type steam methane re-formers show that the capital cost for H2 production plants in the20-200Nm3/day would be$150-180/kW H2for1000units sold.Energy conversion efficien-cies of70-80%are achieved with these re-formers.

A number of industries have developed compact steam methane re-formers for FC applications.Major players in this technology are Haldor Topsoe,Ballard Power Systems, Sanyo Electric,International Fuel Cells(IFC),and Osaka Gas Corp.Praxair,in a joint venture with IFC,has recently commercialized a small stand-alone H2production system based on these annular bed re-formers.Sanyo Electric and Dais-Analytical Co.built residential PEMFCs powered by H2also generated by steam methane re-forming.This technology is being commercialized and offers the attractive-ness of reduced capital costs as compared to conventional small-scale re-formers,as well as compactness.

2.5.1.

3.Plate-type Steam Methane Re-formers.Another design alternative for steam methane re-formers for FC systems is the plate-type reformer.This type of re-former is more compact than the conventional long tube or annular re-formers.The re-former plates are arranged in a stack.One side of the plate is coated with a steam re-forming catalyst, and in the other side,the anode exhaust gas from the FC undergoes catalytic combustion,providing the heat to drive the endothermic steam re-forming.The advantages of this design are its compactness,low cost,good heat transfer,and fast start-up.

Osaka Gas Co.has developed a plate steam methane re-former for use in PEM FCs.246In this design,the different elements,that is,desulfurizer,steam re-former,water gas shift,and CO cleanup,are made up of plates of standard dimensions,greatly reducing the cost.Before commercializa-tion of this technology,the energy conversion efficiency is expected to increase from70to77%by reducing heat losses and increasing the lifetime from5to10years.Another plate-type methane steam re-former design has been provided by GASTEC.During the development of a20kW re-former the performances of various re-formers and combustion catalysts,coatings,and substrate materials were reported.A joint venture between GASTEC and Plug Power was undertaken to develop this plate re-former for residential size fuel cells.

2.5.1.4.Membrane Reactors.In the membrane reactors the steam re-forming,water gas shift,and CO cleanup processes take place in the same reactor.The reactor,which operates under pressure,incorporates on one side a palladium membrane through which hydrogen permeates with a high selectivity.Depending on the temperature,pressure,and reactor length,methane can be quantitatively converted,and pure H2is obtained.As H2is removed once produced,the equilibrium is shifted,thus allowing lower reaction temper-ature and lower cost materials.There are many patents issued on membrane reactor re-forming to a number of companies involved in fuel processor design for FC application and on related ion-transport membranes to oil companies(BP Amoco,Exxon,Standard Oil)and industrial gas companies such as Air Products and Praxair.Argon National Laboratory and Praxair launched a program to develop compact,low-cost hydrogen generators based on a ceramic membrane. Natural gas,steam,and oxygen are re-formed in an auto-thermal reactor,for which oxygen is obtained from air by means of an oxygen transport ceramic membrane that works at temperatures of about1200K.247The oxygen transport membrane has been developed by Praxair,beginning in1997, and is now undergoing pilot demonstration.

2.5.2.Partial Oxidation,Autothermal,and Methanol

Re-formers

A number of companies are involved in developing small-scale partial oxidation re-formers.Small POX re-formers have been built by Arthur D.Little,Epyx,and Nuvera for use in FCs.Epyx is supplying the on-board gasoline processors for the U.S.DOE’s gasoline FC prototype. Similarly,Nuvera shipped gasoline re-formers to automotive companies for testing in FC-powered vehicles.In addition, the consortium McDermott Technology/Catalytica and Hy-drogen Burner Technologies are developing a multifuel processor for a50kW FC.

Autothermal re-formers(ATR)are being developed by a number of companies,mostly for fuel processors of gaso-line,diesel,and logistic fuels and for natural gas fuelled PEM FC cogeneration systems.Principal players in this technology are Honeywell,Daimler-Chrysler,Analytical Power,IdaTech,Hydrogen Burner Technologies,Argonne National Laboratory,Idaho National Energy and Environ-mental Laboratory(INEEL),and McDermott Technologies. INEEL with McDermott and Pacific Gas have recently begun the development of a10kW ATR system for hy-drogen refuelling stations.248In addition,a consortium of McDermott Technologies,Catalytica Advance Technology, Ballard BWX Technologies,and Gibbs and Cox is develop-ing a small autothermal re-former for use with diesel and logistic fuels on ships.Particularly important for this application is the design of a regenerable desulfurization system to operate with naval diesel fuel,which contains up to1wt%sulfur.

Experimental FC vehicles with on-board methanol re-formers have been demonstrated by Daimler-Chrysler, Toyota,and Nissan.In addition,small hydrogen production systems based on methanol re-forming are in commercial use.Although this technology is being developed for fuel processors in on-board FC vehicles,it has also been suggested H2might be produced by methanol steam re-forming at refuelling stations.For this latter application,a hydrogen purification step would be needed,either a pressure swing adsorption unit or a membrane separation stage.The cost of the H2production via steam methanol re-forming might be higher than that of H2from small-scale steam methane re-forming,because methanol is generally,although not always,a more expensive feedstock than natural gas. Costs for methanol are about$11/GJ versus about$4-5/GJ for methane at the refuelling station.Assuming an energy conversion efficiency(feedstock to hydrogen)of75%for each system,feedstock costs alone would be higher for the methanol steam re-former($11/GJ-$5/GJ)/0.75)$8/GJ). The European Commission also funded two projects to develop on-board processors for FC vehicles.The Mercatox project aimed to develop a prototype integrated methanol re-former and selective oxidation system.The re-former

3970Chemical Reviews,2007,Vol.107,No.10Navarro et al.

consists of a series of catalytic plates,with combustion of anode off-gas on one side and re-former on the other side.

2.5.

3.Novel Re-former Technologies

2.5.

3.1.Ion Transport Membrane(ITM)Re-forming.

A large consortium headed by Air Products in collaboration with the U.S.DOE and several companies(Cerametec,Norsk Hydro,McDermott Technology,Chevron,Eltron Research, and Pacific Northwest Laboratory)and academic partners (University of Pennsylvania,University of Alaska,and Pennsylvania State University)is developing a ceramic membrane technology for the generation of H2and syngas (CO+H2)mixtures.

These membranes are nonporous multicomponent oxides suited to work at temperatures above1000K and have high oxygen flux and selectivity.These membranes are known as ITMs.The initial design was carried out for a hydrogen refuelling station dispensing about12000Nm3of H2/day. Initial cost estimations show significant reduction in the cost of on-site high-pressure H2produced according to ITM technology in a plant of capacity in the range of3000-30000 Nm3of H2/day.For instance,the cost of the H2produced via ITM methodology appears to be ca.27%cheaper than the liquid H2transported by road.

In this approach,oxygen is separated from air fed to one side of the membrane at temperatures around300K and moderate pressure(0.03-0.20bar)and reacts on the other side with methane and steam at higher pressure(3-20bar) to form a mixture of CO and H2.Then this mixture can be processed downstream to produce H2or liquid fuels.Among the different geometries employed for the ITM reactor,the flat-plate system offers some advantages because it reduces the number of seals and thus makes for safer operation. 2.5.3.2.Sorbent-Enhanced Re-forming.Sorbent-enhanced steam methane re-forming is another technology explored recently to produce H2.249,250In this concept, calcium oxide is mixed with the steam re-forming catalyst, removing the CO2(and CO)via carbonation of calcium oxide.The resulting H2/CO mixture produced according to this methodology is H2-enriched.Thus,a syngas composition of90%H2,9.5%CH4,0.5%CO2,and CO levels below50 ppm has been reported.This reduces the need for downstream processing(water gas shift and preferential oxidation),which is expensive in a small-scale steam re-former.In addition, removal of CO2by calcium oxide makes the reaction occur at lower temperature(670-770vs1070-1270K),reducing heat loss and material costs.Sorbent-enhanced re-forming technology is still at the demonstration scale and shows promise for low-cost H2production.Critical issues in this methodology are sorbent lifetime and system design.

2.5.

3.3.Plasma Re-formers.Thermal plasma technology is also employed in the production of hydrogen and hydrogen-rich gases from natural gases and other liquid hydrocarbons.The role of plasma is to provide the energy and to create free radicals needed for fuel re-forming.Typical temperatures of thermal plasmas are3000-10000K,which accelerate the kinetics of re-forming reactions even in the absence of a catalyst.Basically,the hydrocarbon and steam are introduced into the reactor and H2,plus other hydrocar-bons,that is,C2H2,C2H4,CO,CO2,are formed.251,252The new designs of plasma re-former are very flexible:it is possible to change the geometry of the electrodes,the reaction volume,and the interelectrode gap.It can operate in a large range of operating conditions,autothermal or steam re-forming conditions,allows the use of different feed stocks, and is very tolerant to sulfur content and carbon deposit.253 The important advantages of this technology for the automo-tive applications are its very short start-up time(few seconds),the large operating range of fuel power(from10 to40kW),and its compactness and robustness.The best steam re-forming showed95%conversion of CH4and specific energy use of14MJ/kg H2,equivalent to about10% of the higher heating value of hydrogen.

2.5.

3.

4.Microchannel Reactors.Over the past few years there has been great interest in finding an improved process that decreases both the investment and operating costs of hydrogen production via steam re-forming reaction.Micro-channel reactors are one of the most attractive options to reduce capital cost by intensifying reactor equipment and reducing operating costs by improving heat and mass transfer.254,255A conventional methane steam re-former is quite large(ca.450000Nm3of H2/day)and operates with a contact time of the order of1s.However,a microchannel plant with the same capacity operates with a contact time below10ms,which corresponds to a plant volume of around 88Nm3,much lower than the2700Nm3required in conventional methane steam re-former plants.256Very re-cently,methane steam re-forming experiments have been conducted at contact times below1ms to demonstrate that the microchannel reactors enable high rates of heat transfer to maintain fast reactions.257Experiments conducted at contact times of0.09-0.9ms in a0.28mm thick porous catalyst structure held adjacent to flow gap revealed that a greater than98%approach to equilibrium in methane conversion can be achieved at0.9ms,and19.7%at0.09 ms.In addition,a model was employed to explore micro-channel reactor structures that minimize heat and mass transfer,and sensitivity results suggested that a high approach to equilibrium could also have been achieved with a10% Rh-4.5%MgO-Al2O3catalyst at0.5ms when it was wash-coated on a thick porous catalyst structure up to0.4mm. The use of microchannel reactors demonstrates that a highly active catalyst allows methane steam re-forming to be carried out with a contact time of less than1ms.Further reduction in contact time may be reasonably achieved by increasing the catalyst thickness in a manner that minimizes heat and mass transport limitations through careful design.

3.Carbon Dioxide-free Reactions

3.1.Methane Decomposition

The decomposition of methane is an attractive alternative for the production of CO x-free hydrogen.258-261However, this process produces a lower yield of hydrogen per carbon atom than other processes(SMR,ATR).The process requires a metal catalyst(Ni,Co,Fe,Pt,...)able to not only break the C-H bonds of the methane molecule but also maintain a high and sustained activity for a long time.Methane decomposition is a moderately endothermic process that requires45.1kJ/mol of H2produced at1073K: Because only hydrogen and carbon structures are produced during methane decomposition,separation of products is not an issue.Another important advantage of the methane decomposition as compared to conventional processes of steam or autothermal processes is the absence of the high-and low-temperature water gas shift reactions and CO2 CH

4

f C+2H2?H1073K)+90.1kJ/mol(19)

Hydrogen Production Reactions from Carbon Feedstocks Chemical Reviews,2007,Vol.107,No.103971

公司项目管理信息系统简介

公司项目管理信息系统简介 （作者：王建华、胡蓉） 《中国水利水电第三工程局有限公司项目管理信息系统》全面覆盖并整合公司办公自动化(包括档案系统)、项目综合管控、市场经营管理、综合项目管理、决策驾驶舱等方面的信息，解决项目部、分局、公司间各为一体的信息孤岛，建成公司集中的信息数据库，最终形成数据仓库，实现公司在项目综合管理方面的全面信息化、高度集中和系统化，对项目管理向精细化、精益化迈进将起到极大的促进作用。 一、项目管理系统的基本情况 1、项目建设背景、建设目标及意义 建设背景：根据建市[2007]72号及建市[2007]241号文件要求，为加快信息化建设步伐，大幅提升企业信息化水平和市场竞争能力，在新修订的建筑业企业资质管理规定中，特级资质标准增加了企业信息化建设考核内容，而综合项目管理系统的应用是信息化建设系统的核心内容，其所占考核权重达50%。为此，为顺利完成企业资质的重新核定工作，根据资质核定信息化建设的考评要求，公司于2009年5月引进了易建科技有限公司研发的《项目管理软件》，并结合公司自身管理需求进行了系统改进和完善，最终形成了《中国水利水电第三工程局有限公司项目管理信息系统》，并于2009年8月正式投入使用。 建设目标：项目管理系统是以项目为管理对象，覆盖项目从招投标-开工-竣工生命周期各个阶段和各个业务环节的管控。通过系统的实施，可建立公司、区域分局(专业分局)、项目部三级项目综合管理信息平台，满足各管理

层级管理需要，实现项目管理的标准化、规范化，以提高项目管理工作的效率和效益。 建设意义和实施必要性：从企业层面讲，综合项目管理系统实施是企业信息化建设的重要组成部分，既是建设部特级资质考评的硬性要求（在建项目使用综合项目管理系统需达项目总数的50%以上，近两年项目竣工管理、档案管理使用率为50%以上），更是提升公司管理水平和竞争力，实现管理现代化与信息化的根本需要，它的实施是现代企业发展的必然趋势。从项目层面讲，系统通过不同的业务模块划分和流程设计，促进项目管理行为规范化、标准化，实现了以数据为依据的科学决策方法，规范了施工管理中的经济活动，由被动管理向主动管理转型，是项目管理模式的重大变革，系统的实施对项目管理向精细化、精益化管理迈进起到极大的促进作用。 2、系统架构 从管理架构划分，系统分为业务执行层、管理控制层和决策规划层，即各项目-区域分局(专业分局)-公司三层结构。通过信息管理平台可实现不同管理层的审批流程、数据汇总、信息传递。其管理层级体系如下：

项目管理系统产品介绍

企业集约化经营项目精益化管理 广联达梦龙建筑施工企业项目管理信息化解决方案

目录 1.卷首语 (3) 2.公司简介 (4) 3.适用范围 (5) 4.管理理念 (6) 4.1.秉持“信息化为企业管理和发展战略服务”理念 (6) 4.2.支持“企业集约化经营，项目精细化管理”落地 (7) 4.3.坚持“围绕核心业务开展企业信息化建设”观点 (9) 5.总体架构 (12) 6.功能概述 (14) 6.1.管理决策平台 (14) 6.2.投标管理 (16) 6.3.合同管理 (17) 6.4.生产与工期管理 (19) 6.5.资金管理 (20) 6.6.物资管理 (21) 6.7.机械设备管理 (23) 6.8.分包管理 (25) 6.9.成本管理 (26) 6.10.技术管理 (29) 6.11.质量管理 (29) 6.12.安全、环境与职业健康管理 (30) 6.13.风险管理 (32) 6.14.竣工管理 (33)

6.15.考核审计管理 (34) 7.产品特点 (36) 7.1.战略决策层 (36) 7.2.运营管控层 (37) 7.3.项目管理层 (38) 8.部分用户 (40)

1.卷首语 建筑施工企业，这支与新中国共同成长的力量，在六十多年国家发展历程中，几代仁人志士们征战南北、夜以继日，为新中国的发展和繁荣立下了卓越功勋。六十多年峥嵘岁月，在取得辉煌成就的同时，施工企业本身的生产和管理水平也取得了长足的进步，从解放初期的主要依靠人工作业到机械化大生产，从机械化大生产到利用各种信息技术辅助生产，施工企业一直在探索着为社会铸造百年工程、让企业基业长青之路。 近几年来，随着国家宏观政策的进一步调控，市场竞争的日趋激烈以及世界经济的不稳定因素进一步突出，施工企业也面临了困难重重却又发展空间巨大的的格局：一些企业在漩涡中艰难迈进，一些企业正破茧成蝶，而另一些企业已是昨日黄花。怎样凤凰涅槃，翱翔于蓝海？施工企业应当顺应历史潮流，借信息技术蓬勃发展之东风，以信息化为载体和手段，重塑企业核心竞争能力，支撑企业管理转型和战略落地，以实现良性发展和可持续发展。 把握时代发展脉搏，历史也终将选择我们。我们这些为中国伟大复兴而呕心沥血的建筑人，必将谱写一曲波澜壮阔的发展诗篇，为中国建筑业的绿色、节能和可持续发展做出卓越贡献，在属于我们的时代留下浓墨重彩的历史烙印。 让我们一起张开臂膀，拥抱信息化，拥抱明天。

公司项目管理信息系统简介

公司项目管理信息系统简介 《中国水利水电第三工程局有限公司项目治理信息系统》全面覆盖并整合公司办公自动化(包括档案系统)、项目综合管控、市场经营治理、综合项目治理、决策驾驶舱等方面的信息，解决项目部、分局、公司间各为一体的信息孤岛，建成公司集中的信息数据库，最终形成数据仓库，实现公司在项目综合治理方面的全面信息化、高度集中和系统化，对项目治理向精细化、精益化迈进将起到极大的促进作用。 一、项目治理系统的差不多情形 1、项目建设背景、建设目标及意义 建设背景：按照建市[2007]72号及建市[2007]241号文件要求，为加快信息化建设步伐，大幅提升企业信息化水平和市场竞争能力，在新修订的建筑业企业资质治理规定中，特级资质标准增加了企业信息化建设考核内容，而综合项目治理系统的应用是信息化建设系统的核心内容，其所占考核权重达50%。为此，为顺利完成企业资质的重新核定工作，按照资质核定信息化建设的考评要求，公司于2009年5月引进了易建科技有限公司研发的《项目治理软件》，并结合公司自身治理需求进行了系统改进和完善，最终形成了《中国水利水电第三工程局有限公司项目治理信息系统》，并于2009年8月正式投入使用。 建设目标：项目治理系统是以项目为治理对象，覆盖项目从招投标- 开工-竣工生命周期各个时期和各个业务环节的管控。通过系统的实施，可建立公司、区域分局(专业分局)、项目部三级项目综合治理信息平台，满足各治理层级治理需要，实现项目治理的标准化、规范化，以提升项目治理工作的效率和效益。 建设意义和实施必要性：从企业层面讲，综合项目治理系统实施是企业信息化建设的重要组成部分，既是建设部特级资质考评的硬性要求（在建项目使用综合项目治理系统需达项目总数的50%以上，近两年项目竣工治理、档案治理使用率为50%以上），更是提升公司治理水平和竞争力，实现治理现代化与信息化的全然需要，它的实施是现代企业进展的必定趋

工程造价咨询类项目管理系统简介

工程造价咨询类项目管 理系统简介 WTD standardization office【WTD 5AB- WTDK 08- WTD 2C】

工程造价咨询类项目管理系统简介行业特点分析 工程造价咨询公司可能面临项目进度和质量控制、收款工作、人员任务日程安排和跟踪等方面繁杂或难以控制等问题，具体如下： A.项目数量较多，工期比较短，按照工程施工阶段的项目收款方式，即项目任务 短平快，收款周期冗长； B.设计人员的任务较多且跨项目，需要与项目组成员沟通的信息和传送的文件较 多； C.项目主管、专业主管管理的项目和专业较多，控制任务进度和质量比较繁杂， 与设计人员的沟通比较多； D.财务人员负责的项目收款需要与项目主管口头沟通，了解任务进度和工程施工 阶段，产生了较大的沟通成本，具体的开票收款过程没有自动提醒功能，催收款工作量较大；伴随项目产生的借支预支费用的报账过程需要口头沟通，凡此种种导致财务人员的任务繁杂，工作流程有待优化； E.公司领导对项目营收、项目进度情况、收款进度，或进一步具体到人员任务日 程表、工作状况、签单收款的环比同比分析，年度、季度、月度、周的整体情况总结和计划等方面难以详实的了解； F.项目的经验、成果、过程中遇到的问题及采用的解决方案或方法，相关的参考 文档资料需要建设知识库、问题库，便于以后参考、借鉴或规避。 软件特点 A.完整控制项目生命周期（及开票收款过程）过程，包括以下内容： 项目管理主线流程：创建项目 -> 分配专业 -> 分配任务 -> 执行任务 -> 归 档； 项目工期调整日志； 项目联系人及备注； 合同金额调整日志； 任务工期调整日志； 填报工作日志；

供应商评审表

供应商评审表 供应商名称供应商编号 供货类别评审时间年月日评审类别□认证，现场评审；□认证，会议评审；□复审，现场评审；□复审，会议评审 项目评价内容参考评价标准目标得分评价记录评价人 质量质量管理 体系 供应商通过第三方质量管理体系的 认证或建立了相应的质量管理体系 10 产品追溯 系统 供应商建立了完善的产品追溯系统， 能够实现有效追溯 10 检验能力 供方检验设备等能否满足产品检验 要求？ 5 样品/来料 质量 样品测试是否合格/ 来料质量是否 满足公司质量目标？ 20 技术渠道控制 是生产原厂，或有原厂授权代理、经 销证明 5 加工能力 查看供方的生产环境、技术设施、工 艺流程、面对的客户群等方面的状况 10 成本成本 价格在同行业中合理，且能配合我司 成本下降要求 5 财务状况银行信誉、财务状况良好 5 交付交付状况 采购提前期和交期能够满足公司要 求 10 紧急需求 满足 有完善的机制来应对紧急定单/ 能 够满足紧急订单要求 5 备货 供应商能支持凯龙的备货需求，并按 要求及时足量备货 5 服务客诉和不 良品处理 对投诉能及时回复并制定预防措施； 对不合格品的退换和分析、改善及时 有效 5 仓储服务 供方建立相关文件规范仓储相关要 求，符合相关体系要求 5 目前资格□优秀供应商□合格供应商□试用供应商 □不合格供应商□待认证供应商□其它 总计得分（共100分） 审核结论: □通过，合格供应商□试用，辅导后再评审□不合格供应商（□辅导后再评审□淘汰） 评审团队 Q A 部门审核批准 备注：用于新供方引入时，可参考之前的调查问卷内容进行评分，判定标准为：总计得分T≥75分为合格供应商； 60≤T＜75分为试用供应商；T＜60分为不合格供应商；

工程造价咨询类项目管理系统简介

工程造价咨询类项目管理系统简介 行业特点分析 工程造价咨询公司可能面临项目进度和质量控制、收款工作、人员任务日程安排和跟踪等方面繁杂或难以控制等问题，具体如下： A.项目数量较多，工期比较短，按照工程施工阶段的项目收款方式，即项目任务短平快，收款周期 冗长； B.设计人员的任务较多且跨项目，需要与项目组成员沟通的信息和传送的文件较多； C.项目主管、专业主管管理的项目和专业较多，控制任务进度和质量比较繁杂，与设计人员的沟通 比较多； D.财务人员负责的项目收款需要与项目主管口头沟通，了解任务进度和工程施工阶段，产生了较大 的沟通成本，具体的开票收款过程没有自动提醒功能，催收款工作量较大；伴随项目产生的借支预支费用的报账过程需要口头沟通，凡此种种导致财务人员的任务繁杂，工作流程有待优化； E.公司领导对项目营收、项目进度情况、收款进度，或进一步具体到人员任务日程表、工作状况、 签单收款的环比同比分析，年度、季度、月度、周的整体情况总结和计划等方面难以详实的了解； F.项目的经验、成果、过程中遇到的问题及采用的解决方案或方法，相关的参考文档资料需要建设 知识库、问题库，便于以后参考、借鉴或规避。 软件特点 A.完整控制项目生命周期（及开票收款过程）过程，包括以下内容： 项目管理主线流程：创建项目-> 分配专业-> 分配任务-> 执行任务-> 归档； 项目工期调整日志； 项目联系人及备注； 合同金额调整日志； 任务工期调整日志； 填报工作日志； 工作联系单：项目组成员的沟通和文件传递； 任务流程审批； 问题库记录项目产生的问题及处理方案 项目成果文件 工程阶段为地基验收、主体验收和竣工验收时提醒财务开展开票收款工作 项目相关的费用收支：开票收款（过程管理）、保证金、借支预支、费用报销及其他收支

项目管理系统介绍

项目管理系统介绍 建业科技项目管理系统以项目管理为核心，是多方位覆盖项目管理的信息化系统，是公司信息化应用体系的核心组成部分。系统以合同预算和目标成本为龙头，以合同为约束，以资金为主线，以合同预算、目标成本、实际成本三算对比为核心，以成本控制为目标，实现在限定的时间内，在限定的资源（工、料、机等）条件下，以尽可能快的速度、尽可能低的成本圆满的完成项目的任务，系统对工程项目合同预算、进度、合同、采购、材料、设备、质量、安全等进行全面综合管理；通过对成本、进度、资金、质量安全等方面的控制，以及对合同、变更、结算、支付等要素的流程化管理，来提高企业对工程项目的综合配套能力，同时兼顾了知识管理、持续发展的战略思路，纵向贯穿招标、分包、采购、施工、竣工的全过程，横向涉及公司-项目部的各个岗位，是一套满足施工项目管理的全方位综合管理系统。 架构图 系统特点： １.通过预算管理和成本管理，以三算对比为核心，以成本控制为目标，实现动态成本核算与分析，实时监控项目中的工、料、机的实际成本，控制成本超支、为索赔签证提供依据，

提高对工程项目的管控能力，从而提升企业的盈利能力； ２.全面整合工程项目和企业资源，创造一个高效运作、管理规范的组织； 通过标准化工作流程和信息化手段，为企业创造协同工作环境，突破地域界限和管理边界，３.破解项目工地“点多面广”所带来的各种问题，提高企业的管理水平和效率； ４.通过提高企业的市场开拓和营销能力、项目管理能力和资源整合能力，构筑企业核心竞争力； ５.通过项目综合管理系统中的数据统计与分析，根据积累沉淀的数据进行数据挖掘，可以对以往的项目情况进行总结和分析，提高企业的辅助决策支持能力； 系统价值： １.项目进度透明化管理； ２.项目过程中技术、质量、安全得到规范控制； ３.项目过程中种类和数量繁多的资料得到有序管理； ４.项目过程中风险可以及时发现； ５.可以实时监控项目中的工、料、机实际成本。

项目管理系统使用管理办法

中信国际合作公司项目管理系统 使用管理办法 中信国际合作公司项目管理系统（以下简称项目管理系统）是通过互联网实现公司各项目规范管理的工作平台，为了规范系统使用行为、有效利用网络资源、保证项目管理系统的安全高效运行，特制定本管理办法。 一、项目管理系统简介 项目管理系统目前设置了“协同办公”、“项目计划”、“项目合同”、“资金管理”、“文档管理”、“商务管理”、“综合查询”、“基础资料”等模块，还将陆续推出“采购管理”、“质量管理”、“风险管理”等模块。 1、协同办公：包括项目讨论、项目公告、项目会议、公司公告、公司讨论、部门讨论、消息信息、办文流转、基础设置等功能。 2、项目计划：包括进度计划、项目PCWBS（工作任务分解）、项目FWBS（费用分解）、项目部门、项目OBS（组织结构分解）、赢得值、基础设置等功能。 3、项目合同：包括合同信息、合同收付款计划、合同实际收付款信息、合同资金对比表、基础设置等功能。 4、资金管理：包括非合同资金收付款计划、资金收入支出单、现金流、基础设置等功能。 5、文档管理：管理项目管理系统内所有相关文档信息。 6、商务管理：包括银行授信、保函信息、信用证信息、承兑汇票信息、保函使用管理、信用证使用管理、承兑汇票使用管理、基础设置等功能。 7、综合查询：从公司领导和项目部领导的角度，查看公司现有各项目的整体运转状况。

8、基础资料：包括相关单位、国家地区、公共信息、货币与汇率、用户管理、权限设置等功能。 9、采购管理：待定。 10、质量管理：待定。 11、风险管理：待定。 项目管理系统由人事部信息管理员负责技术支持；计财部负责基础资料中货币与汇率、商务管理中银行授信与公司开立保函部分；市场部负责基础资料中相关单位和国家地区部分；合同部负责合同管理中合同类型等基础信息定义；各部门负责公共信息内与本部门有关栏目的维护；各业务、项目部门负责本部门各项目中进度计划、合同、资金、文档、商务等信息的维护。 二、项目管理系统的管理原则 1、项目管理系统的管理，必须遵照《中华人民共和国计算机信息系统安全保护条例》等相关的法律规定、中信集团公司关于计算机和网络安全的相关规定，以及《中信国际合作公司员工计算机管理办法》、《中信国际合作公司文件审批制度》等有关规定。 2、项目管理系统中各模块的责任部门，应切实负起责任，及时更新各项数据，以保证整个系统的正常运转。各信息发布部门，在项目管理系统上发布的信息，格式要求统一，内容要真实准确、健康向上、及时全面。 3．项目管理系统中部分栏目的设置，由公司各部门负责提出方案，人事部根据授权或报公司领导审批，后经项目管理系统软件供应商进行实施。 三、项目管理系统账号管理 1、账号申请 （1）项目管理系统的开户原则见《中信国际合作公司员工招聘管理办法》，

计划建设管理系统介绍

计划建设管理系统介绍 1.系统概况 计划建设管理系统以项目全生命周期为主线、以立项为线头，实现资源与进度的合理匹配、进度与成本的过程管控，从成本视角、进度视角、资源视角对项目实现资金管控、进度管控、物资管控、能力管控，实现投资项目的可管理、可监控、可审计、可追溯。 实现规范化、标准化项目管理，通过项目集、单项工程与单位工程的结合，实现从宏观计划到具体工程实施，深入项目精细化、精益化管理，并且引导集成化协同管理以及融合集约化管理的思路，实现企业真正的并且是有效的经营管理、成本管理、进度管理和生产与资源管理。 系统以企业决策层和各级管理层、项目施工层为服务对象，对项目及其资源进行计划、组织、配备、执行、控制、分析、调整，保证工程项目在约束条件内完成预定的目标，提高企业对成本、进度、质量、安全的控制能力，以及对设计、合同、变更、支付、资金、信息、风险的管理能力。 系统从单项工程层面上包括规划管理、投资计划管理、项目全生命周期管理，从单位工程层面实现设计与变更管理、施工过程管理、监理日志与问题管理、物料出入库、采购与订单管理、合作伙伴管理、现场管理等项目综合管理功能，形成一个围绕工程项目投资与建设的全方位、完整周期、整合型的信息化管理体系。

2.功能组成 功能结构图

业务流程图 3.功能介绍 3.1投资计划管理 3.1.1投资计划编制 根据总部计划部门要求启动年度计划编制工作，依据规划期初年项目列表形成的年度投资计划以及年度投资计划编制要求，编制年度项目投资计划和资本开支计划初稿，评审通过后形成年度投资计划需求并报送总部。

相关信息应包括项目或项目集名称、投资分类、建设项目属性（新/续建项目）、投资主体、项目投资总规模及年度资本开支计划、建设规模和建设内容。 3.1.2投资计划下达 依据总部下达的年度项目投资计划，分解形成本公司年度项目投资计划。其中，刚性管理项目集在项目投资上限内制订分地域、分批次项目投资计划，自主安排投资在投资总额上限内制订具体项目投资计划。本公司年度投资计划经本公司管理层审批通过后下达执行。 3.1.3投资计划执行监控 定期跟踪年度投资计划执行情况，将项目执行情况按照总部下达的项目集进行归集。当出现以下情况之一时及时预警：1、某项目集的投资或能力建设进度完成值低于进度目标值； 2、某项目集的预计完成投资或建设规模超过立项规模； 3、所有项目集的预计当年完成资本开支之和超出年度计划值。 3.1.4投资计划滚动调整 根据总部计划部门要求启动年度计划调整工作，依据计划内项目执行情况以及计划外项目需求，编制年度项目投资调整计划和资本开支调整计划初稿，评审通过后形成年度投资计划调整需求并报送总部。

人事管理系统项目简介及功能描述

人事管理系统项目简介及功能描述

文档信息： 文档变更历史： 审核结果：

目录 1 编写目的 (4) 2 项目背景 (4) 2.1 公司现状 (4) 2.2 解决方案 (5) 2.2.1 项目范围 (5) 3 项目要求 (5) 4 功能简介 (5) 4.1 Web 系统 (6) 4.1.1 查询员薪资料 (6) 4.1.2 请假申请 (6) 4.1.3 请假审核 (6) 4.1.4 考勤管理 (6) 4.1.5 提交加班申请 (6) 4.1.6 加班审核 (7) 4.1.7 业绩评定 (7) 4.1.8 薪资查询 (7) 4.2 Windows 系统 (8) 4.2.1 员薪资料管理 (8) 4.2.2 部门管理 (8) 4.2.3 请假管理 (8) 4.2.4 考勤管理 (8) 4.2.5 加班管理 (9) 4.2.6 薪资管理 (9) 4.2.7 安全管理 (9) 4.3 SQL Server 数据库系统 (9) 4.3.1 数据存储 (9) 4.3.2 数据管理 (10) 4.3.3 数据维护 (10)

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公司项目管理信息系统 简介 Company number【1089WT-1898YT-1W8CB-9UUT-92108】

公司项目管理信息系统简介 （作者：王建华、胡蓉） 《中国水利水电第三工程局有限公司项目管理信息系统》全面覆盖并整合公司办公自动化(包括档案系统)、项目综合管控、市场经营管理、综合项目管理、决策驾驶舱等方面的信息，解决项目部、分局、公司间各为一体的信息孤岛，建成公司集中的信息数据库，最终形成数据仓库，实现公司在项目综合管理方面的全面信息化、高度集中和系统化，对项目管理向精细化、精益化迈进将起到极大的促进作用。 一、项目管理系统的基本情况 1、项目建设背景、建设目标及意义 建设背景：根据建市[2007]72号及建市[2007]241号文件要求，为加快信息化建设步伐，大幅提升企业信息化水平和市场竞争能力，在新修订的建筑业企业资质管理规定中，特级资质标准增加了企业信息化建设考核内容，而综合项目管理系统的应用是信息化建设系统的核心内容，其所占考核权重达50%。为此，为顺利完成企业资质的重新核定工作，根据资质核定信息化建设的考评要求，公司于2009年5月引进了易建科技有限公司研发的《项目管理软件》，并结合公司自身管理需求进行了系统改进和完善，最终形成了《中国水利水电第三工程局有限公司项目管理信息系统》，并于2009年8月正式投入使用。 建设目标：项目管理系统是以项目为管理对象，覆盖项目从招投标-开工-竣工生命周期各个阶段和各个业务环节的管控。通过系统的实施，可建立公司、区域分局(专业分局)、项目部三级项目综合管理信息平

台，满足各管理层级管理需要，实现项目管理的标准化、规范化，以提高项目管理工作的效率和效益。 建设意义和实施必要性：从企业层面讲，综合项目管理系统实施是企业信息化建设的重要组成部分，既是建设部特级资质考评的硬性要求（在建项目使用综合项目管理系统需达项目总数的50%以上，近两年项目竣工管理、档案管理使用率为50%以上），更是提升公司管理水平和竞争力，实现管理现代化与信息化的根本需要，它的实施是现代企业发展的必然趋势。从项目层面讲，系统通过不同的业务模块划分和流程设计，促进项目管理行为规范化、标准化，实现了以数据为依据的科学决策方法，规范了施工管理中的经济活动，由被动管理向主动管理转型，是项目管理模式的重大变革，系统的实施对项目管理向精细化、精益化管理迈进起到极大的促进作用。 2、系统架构 从管理架构划分，系统分为业务执行层、管理控制层和决策规划层，即各项目-区域分局(专业分局)-公司三层结构。通过信息管理平台可实现不同管理层的审批流程、数据汇总、信息传递。其管理层级体系如下：

工程项目信息管理系统-概要设计

工程项目信息管理系 统概要设计

目录 第一章. 项目背景 (3) 第二章. 建设目标 (4) 第三章. 建设方针................... 第四章. 设计思路 (4) 第五章. 总体设计 (5) 5.1 技术路线 ....................... 5.2 功能结构 .............................. 5.3 整体架构 ....................... 第六章. 功能设计 (14) 6.1 教育资源云服务平台................ 6.2 直、点播在线学习平台.............. 6.3 教师绩效管理系统............... 6.4 基地统一信息服务平台.............. 6.5 基地内部工作流服务系统............. 第七章. 系统特点 (21) 7.1 先进的系统构架................. 7.1.1 软件系统构架的优势............ 7.1.2 硬件构架的优势.............. 7.2 高性价比 ....................... 7.2.1 成熟而开放的软件系统降低了研发成本....... 7.2.2 统一的硬件平台降低了设备采购和更新成本第八章. 总结...................... 错误! 未定义书签 错误! 未定义书签。 5错误未定义书 错误! 未定义书 签错误! 未定义 书签错误! 未定 义书签错误! 未 定义书签错误! 错误! 未定义书签。错误! 未定义书签。错误! 未定义书签。错误! 未定义书签。错误! 未定义书签。错误! 未定义书签。

供应商管理-供应商现场评审表

工廠地址：廠方電話﹕廠方陪稽﹕ 廠方傳真﹕ 稽核人員簽名﹕ 承辦﹕ 核准﹕ 審核﹕ ＸＸ電子有限公司 供应商現場評審表 廠方代表﹕工廠名稱﹕供應產品﹕ 稽核編號﹕ 稽核日期﹕ 稽核人員﹕

項次評分標準實際評分 備注 13233343536373839310311312313314315316317318319320321 3 有無建立不良限度樣品﹖限度樣品是否處于隨時能夠取出的狀態﹖ 項目 針對各種產品是否有做品質履歷表﹖ 量測工具及試驗設備有無經過校驗﹖校驗是否有記錄﹖檢驗后是否有記錄與標示﹖記錄是否完整﹑真實﹖是否具備外觀﹑尺寸﹑功能﹑包裝之檢驗﹖針對電鍍類﹑五金類材料或成品是否有做相關的可靠性試驗﹖試驗結果是否有記錄﹖針對每日進料狀況有無進行統計﹖并制作日報﹑周報﹑月報的形式進行分析﹖IQC 各員是否能熟練使用各類檢測儀器﹖有無培訓記錄﹖ 各類儀器有無操作說明書﹖說明書上是否有規定量測的相關參數﹖針對庫存及重工后之產品是否有重檢﹖有無記錄﹖重檢不合格時有無依《不合格品管制程序》作業﹖ IQC 人員是否定期對材料倉在先進先出及過期材料的管控﹑存放﹑安全性等方面進行稽核﹖ IQC 各員是否熟悉進料檢驗流程﹖檢驗判定標准﹖ 當供應商來料連續出現品質異常時﹐IQC 有無進行加嚴檢驗﹖ 當加嚴檢驗轉換成正常或減量檢驗時有無明確規定﹖程序文件上有界定嗎﹖ IQC 人員對各類量測儀器是否有進行日常保養維護﹖被稽核部門﹕品質管理 ( IQC ) 是否有明確的抽樣計划及進料檢驗流程并確實遵照作業?檢驗后之狀態區分是否書面規定并執行﹖ＸＸ電子有限公司 供应商現場評審表 是否有足夠的檢驗試驗設備﹖狀態是否良好﹖ 不良限度樣品是否有制樣人﹑制樣日期﹑不良現象的描述﹑判定結果﹑有效期限﹑核准人﹖公司各員是否熟悉品質目標﹖品質政策﹖是否有各材料之檢驗作業指導書﹖是否有檢驗判定標准作依據確實遵照執行﹖IQC 人員作業時是否持有相關產品的樣品承認書進行檢驗﹖文件版本是否為最新版﹖ 樣品承認書﹑工程圖面﹑ECN ﹑工程樣品是否及時歸檔并進行整理標示﹖是否能隨時調出各類文件﹖