DETAILED DESCRIPTION OF THE INVENTION

[0047] The invention relates to a method for producing a hydrogen-rich gas, such as a hydrogen-rich syngas. According to the method a CO-containing gas such as a syngas contacts a water gas shift catalyst, in the presence of water, preferably a stoichiometric excess of water, preferably at a reaction temperature of less than about 450° C. to produce a hydrogen-rich gas, such as a hydrogen-rich syngas. The reaction pressure is preferably not more than about 10 bar. The invention also relates to a water gas shift catalyst itself and to apparatus such as water gas shift reactors and fuel processing apparatus comprising such WGS catalysts.

[0048] A water gas shift catalyst according to the invention comprises:

[0049] a) at least one of Rh, Ni, Pt, their oxides and mixtures thereof,

[0050] b) at least one of Cu, Ag, Au, their oxides and mixtures thereof, and

[0051] c) at least one of K, Cs, Sc, Y, Ti, Zr, V, Mo, Re, Fe, Ru, Co, Ir, Pd, Cd, In, Ge, Sn, Pb, Sb, Te, La, Ce, Pr, Nd, Sm, Eu, their oxides and mixtures thereof The WGS catalyst may be supported on a carrier, such as any one member or a combination of alumina, zirconia, titania, ceria, magnesia, lanthania, niobia, zeolite, pervoskite, silica clay, yttria and iron oxide.

[0052] The WGS catalysts of the invention comprise combinations of at least three metals or metalloids, selected from at least three groups as indicated above, in each and every possible permutation and combination, except as specifically and expressly excluded. Although particular subgroupings of preferred combinations of metals or metalloids are also presented, the present invention is not limited to the particularly recited subgroupings.

[0053] An alternate embodiment of the invention comprises a water gas shift catalyst comprising Rh, its oxides or mixtures thereof, Pt, its oxides or mixtures thereof, and Ag, its oxides or mixtures thereof.

[0054] Discussion regarding the particular function of various components of catalysts and catalyst systems is provided herein solely to explain the advantage of the invention, and is not limiting as to the scope of the invention or the intended use, function, or mechanism of the various components and/or compositions disclosed and claimed. As such, any discussion of component and/or compositional function is made, without being bound by theory and by current understanding, unless and except such requirements are expressly recited in the claims. Generally, for example, and without being bound by theory, the metals of component a), Rh, Ni and Pt have activity as WGS catalysts. The metals or metalloids of components b) and c) may themselves have activity as WGS catalysts but function in combination with Rh, Ni and/or Pt to impart beneficial properties to the catalyst of the invention.

[0055] Catalysts of the invention can catalyze the WGS reaction at varying temperatures, avoid or attenuate unwanted side reactions such as methanation reactions, as well as generate a hydrogen-rich gas, such as a hydrogen-rich syngas. The composition of the WGS catalysts of the invention and their use in WGS reactions are discussed below.

[0056] 1. Definitions

[0057] Water gas shift (“WGS”) reaction: Reaction which produces hydrogen and carbon dioxide from water and carbon monoxide, and vice versa: 1

[0058] Generally, and unless explicitly stated to the contrary, each of the WGS catalysts of the invention can be advantageously applied both in connection with the forward reaction as shown above (i.e., for the production of H ₂ ), or alternatively, in connection with the reverse reaction as shown above (i.e., for the production of CO). As such, the various catalysts disclosed herein can be used to specifically control the ratio of H ₂ to CO in a gas stream.

[0059] Methanation reaction: Reaction which produces methane and water from a carbon source, such as carbon monoxide or carbon dioxide, and hydrogen: 2

[0060] “Syngas ” (also called synthesis gas): Gaseous mixture comprising hydrogen (H ₂ ) and carbon monoxide (CO) which may also contain other gas components such as carbon dioxide (CO ₂ ), water (H ₂ O), methane (CH ₄ ) and nitrogen (N ₂ ).

[0061] LTS: Refers to “low temperature shift” reaction conditions where the reaction temperature is less than about 250° C., preferably ranging from about 150° C. to about 250° C.

[0062] MTS: Refers to “medium temperature shift” reaction conditions where the reaction temperature ranges from about 250° C. to about 350° C.

[0063] HTS: Refers to “high temperature shift” reaction conditions where the reaction temperature is more than about 350° C. and up to about 450° C.

[0064] Hydrocarbon: Compound containing hydrogen, carbon, and, optionally, oxygen.

[0065] The Periodic Table of the Elements is based on the present IUPAC convention, thus, for example, Group 11 comprises Cu, Ag and Au. (See http://www.iupac.org dated May 30, 2002.)

[0066] As discussed herein, the catalyst composition nomenclature uses a dash (i.e., “-”) to separate catalyst component groups where a catalyst may contain one or more of the catalyst components listed for each component group, brackets (i.e., “{ }”) are used to enclose the members of a catalyst component group, “{two of . . . }” is used if two or more members of a catalyst component group are required to be present in a catalyst composition, “blank” is used within the “{ }” to indicate the possible choice that no additional element is added, and a slash (i.e., “/”) is used to separate supported catalyst components from their support material, if any. Additionally, the elements within catalyst composition formulations include all possible oxidation states, including oxides, salts or mixtures thereof

[0067] Using this shorthand nomenclature in this specification, for example, “Pt—{Rh, Ni}—{Na, K, Fe, Os}/ZrO ₂ ” would represent catalyst compositions containing Pt, one or more of Rh and Ni, and one or more of Na, K, Fe, and Os supported on ZrO ₂ ; all of the catalyst elements may be in any possible oxidation state, unless explicitly indicated otherwise. “Pt—Rh—Ni-{two of Na, K, Fe, Os)” would represent a supported or unsupported catalyst composition containing Pt, Rh, and Ni, and two or more of Na, K, Fe, and Os. “Rh—{Cu,Ag,Au}—{Na, K, blank}/TiO ₂ ” would represent catalyst compositions containing Rh, one or more of Cu, Ag and Au, and, optionally, one of Na or K supported on TiO ₂ .

[0068] 2. WGS Catalyst

[0069] A water gas shift catalyst of the invention comprises:

[0070] a) at least one of Rh, Ni, Pt, their oxides and mixtures thereof,

[0071] b) at least one of Cu, Ag, Au, their oxides and mixtures thereof, and

[0072] c) at least one of K, Cs, Sc, Y, Ti, Zr, V, Mo, Re, Fe, Ru, Co, Ir, Pd, Cd, In, Ge, Sn, Pb, Sb, Te, La, Ce, Pr, Nd, Sm, Eu, their oxides and mixtures thereof Another water gas shift catalyst according to the invention comprises Rh, its oxides or mixtures thereof, Pt, its oxides or mixtures thereof, and Ag, its oxides or mixtures thereof. Suitable carriers for supported catalysts are discussed below.

[0073] The catalyst components are typically present in a mixture of the reduced or oxide forms; typically one of the forms will predominate in the mixture. A WGS catalyst of the invention may be prepared by mixing the metals and/or metalloids in their elemental forms or as oxides or salts to form a catalyst precursor. This catalyst precursor mixture generally undergoes a calcination and/or reductive treatment, which may be in-situ (within the reactor), prior to use as a WGS catalyst. Without being bound by theory, the catalytically active species are generally understood to be species which are in the reduced elemental state or in other possible higher oxidation states. The catalyst precursor species are believed to be substantially completely converted to the catalytically active species by the pre-use treatment. Nonetheless, the catalyst component species present after calcination and/or reduction may be a mixture of catalytically active species such as the reduced metal or other possible higher oxidation states and uncalcined or unreduced species depending on the efficiency of the calcination and/or reduction conditions.

[0074] A. Catalyst Compositions

[0075] As discussed above, one embodiment of the invention is a catalyst for catalyzing the water gas shift reaction (or its reverse reaction). According to the invention, a WGS catalyst may have the following composition:

[0076] a) at least one of Rh, Ni, Pt, their oxides and mixtures thereof,

[0077] b) at least one of Cu, Ag, Au, their oxides and mixtures thereof, and

[0078] c) at least one of K, Cs, Sc, Y, Ti, Zr, V, Mo, Re, Fe, Ru, Co, Ir, Pd, Cd, In, Ge, Sn, Pb, Sb, Te, La, Ce, Pr, Nd, Sm, Eu, their oxides and mixtures thereof

[0079] Another water gas shift catalyst according to the invention comprises Rh, its oxides or mixtures thereof, Pt, its oxides or mixtures thereof, and Ag, its oxides or mixtures thereof

[0080] The amount of each component present in a given catalyst according to the present invention may vary depending on the reaction conditions under which the catalyst is intended to operate. Generally, a Group 8, 9 or 10 metal component, may be present in an amount ranging from about 0.01 wt. % to about 10 wt. %, preferably about 0.01 wt. % to about 2 wt. %, and more preferably about 0.05 wt. % to about 0.5 wt. %. Group 11 metals may be present in a range ranging from about 0.05 wt. % to about 5 wt. %, preferably about 0.1 wt. % to about 3 wt. %. The lanthanide elements may be present, typically, in amounts ranging from about 0.05 wt. % to about 20 wt. %, preferably about 0.1 wt. % to about 15 wt. %. The main group and metalloid elements may be present in amounts ranging, generally, from about 0.01 wt. % to about 15 wt. %, preferably about 0.02 wt. % to about 10 wt. %.

[0081] The above weight percentages are calculated on the total weight of the catalyst component in its final state in the catalyst composition after the final catalyst preparation step (i.e., the resulting oxidation state or states) with respect to the total weight of all catalyst components plus the support material, if any. The presence of a given catalyst component in the support material and the extent and type of its interaction with other catalyst components may effect the amount of a component needed to achieve the desired performance effect.

[0082] Other WGS catalysts which embody the invention are listed below. Utilizing the shorthand notation discussed above, where each metal may be present in its reduced form or in a higher oxidation state, the following compositions are examples of preferred catalyst compositions:

[0083] {Pt, Rh}—{Cu, Ag, Au}—{Ti, Zr, Fe, Ru, Ir, Pd}.

[0084] Ni—{Cu, Au}—{Fe, Co, Cd, In, Ge, Sn, Pb Te}—{Cr, Mn, blank}.

[0085] Rh—{Cu, Ag, Au}—{Ti, Fe, Co, Ge, Sn, Sb, Ce}.

[0086] {Rh, Ni, Pt}—{Cu}—{Ge, Sn, Sb}.

[0087] Pt—Au—Ti.

[0088] Pt—Au—Ir.

[0089] Pt—{Cu, Ag, Au}—Pd.

[0090] {Pt, Rh}—{Cu, Ag, Au}—Pd.

[0091] One preferred quaternary catalyst is both of Pt and Rh in combination with one or more of Cu, Ag, or Au, and one or more of Y, V, Mo, Re, Fe, Ge, Sn, Sb, La, Ce, Pr, Nd, Sm or Eu. Another preferred embodiment is one or more of Pt or Rh, in combination with two or more of Cu, Ag or Au, and two or more of Fe, Ge or Sb.

[0092] The catalysts may be more advantageously applied in specific operating temperature ranges. For instance, some Ni containing catalysts are generally more active and selective under HTS conditions than at lower temperature ranges. Specifically, for example, a Ni-containing catalyst, including especially noble metal free Ni-containing catalyst, with either or both of Cu or Au present as component b) and at least one of component c) chosen from among the following: Fe, Co, Cd, In, Sn and Te is preferred at HTS conditions.

[0093] Other preferred catalyst compositions which may be applied under HTS reaction conditions include {Rh, Pt}—{Cu, Ag, Au}—{Ti, Zr, Fe, Ru, Ir, Pd};

[0094] Rh—{Cu, Ag, Au}—{Ti, Fe, Co, Ge, Sn, Sb, Ce};

[0095] {Rh, Ni, Pt}—Cu—{Ge, Sn, Sb}; and

[0096] Pt—Au—Ti.

[0097] A number of catalyst compositions provide enhanced activity and selectivity over baseline formulations at both MTS and HTS. Specifically, the following compositions were found to perform well over both MTS and HTS reaction conditions: Pt—Au—Ir; Pt—{Cu, Ag, Au}—Pd; and {Pt, Rh}—{Cu, Ag, Au}—Pd.

[0098] B. Catalyst Component a): Rh, Ni, Pt

[0099] A first component in a catalyst of the invention is Rh, Ni or Pt, component a). These metal components may be present in a combination of its reduced form and its oxide. Catalysts of the invention may contain mixtures of these metals. Rh, Ni, and Pt each catalyze the WGS reaction.

[0100] Rh and Ni are examples of metals that also promote the competing methanation reaction but by doping with other catalyst components, such as those represented by, for example, Group 11 or main group metals, can provide highly active and selective WGS performance.

[0101] Unmodified Rh has been shown to catalyze the methanation reaction under WGS conditions. However, according to the present invention, Rh may be converted to a highly active and selective WGS catalyst by adjusting the Rh loading and by combining with other catalyst components (e.g., group 8 of main group components) which may moderate the activity of the methanation reaction. In combinations of the invention, Pt was found to efficiently alter the selectivity of unmodified Rh. According to the present invention, various dopants may be added to Pt—Rh and some preferred catalysts include Pt—Rh—{Cu,Ag,Au}—{Sn,Sb,Ge,Fe} as well as the Pt-free system: Rh—{Cu,Ag,Au}—{Sn,Sb,Ge,Fe}. Those catalysts are highly active and selective WGS catalysts, and exhibit increased selectivity for the WGS reaction over the competing methanation reaction.

[0102] Pt—Rh can also be gradually moderated, while enhancing WGS selectivity at the expense of activity, by adding catalyst components such as, Group 11 metals and/or main group metals, for example, Sn, Sb or Ge. One especially preferred catalyst formulation comprises Pt—Rh—Ag.

[0103] Rh and/or Ni containing catalysts, preferably Rh and/or Ni-containing catalysts that are substantially platinum-free compositions (i.e., have an essential absence of Pt) may advantageously include at least one performance additive, preferably selected from Cu, Ag, and Au, with one or more of Fe, Co, Sn, Sb and Ge.

[0104] Ni, supported or unsupported, is recognized as a water gas shift catalyst; unfortunately, like Rh, Ni alone typically will promote the methanation reaction. By moderating Ni's methanation activity with, for example, one or more of Cu or Au, and one or more of Co, Cd, In, Ge, Sn, Te, Fe and Pb the resulting catalyst composition provides acceptable WGS performance at the desired reaction conditions. Mn and Cr may be added to stabilize the nickel against sintering at high temperatures. Preferably the Ni catalyst is supported on zirconia. Most preferred is when the Ni/ZrO ₂ catalyst is moderated with Cu and one of more of In, Sn, Te and Fe.

[0105] Unsupported or bulk Ni's methanation activity may also be effectively moderated by the addition of components such as Cd, Ge, Pb and In. Preferably high dopant concentrations along with reduction temperatures of about 450° C. are utilized to prepare the doped bulk Ni catalyst compositions which compare favorably to Pt/ZrO ₂ standard catalysts.

[0106] C. Catalyst Components b) and c): “Functional” Metals or Metalloids

[0107] The WGS catalysts of the invention contain at least three metals or metalloids. In addition to component a), discussed above, a WGS catalyst contains metals or metalloids which, when used in combination with Rh, Ni and/or Pt, function to impart beneficial properties to the catalyst of the invention. A catalyst of the invention, then, further comprises at least one of Cu, Ag, Au, their oxides and mixtures thereof, component b); and at least one of K, Cs, Sc, Y, Ti, Zr, V, Mo, Re, Fe, Ru, Co, Ir, Pd, Cd, In, Ge, Sn, Pb, Sb, Te, La, Ce, Pr, Nd, Sm, Eu, their oxides and mixtures thereof, component c). Another catalyst of the invention comprises Rh, its oxides or mixtures thereof, Pt, its oxides or mixtures thereof, and Ag, its oxides or mixtures thereof.

[0108] A catalyst of the invention may include Au which has been found to be an efficient WGS selectivity-enhancing component to each of Pt and Rh alone or in combination, as well as to each of Pd and Ir, alone or in combination. Au is also a metal that modifies WGS catalyst activity that is otherwise too active, particularly at the higher WGS temperatures of 350 to 400° C. As an example, Pt is known to be an active and selective WGS catalyst under MTS conditions, and it is desirable that the WGS selectivity of a Pt containing catalyst be maintained under HTS operating conditions. Since, Au has been found to function predominantly by moderating catalyst activity and has not, generally, exhibited enhanced catalyst activity. The presence of Au as a component may result in catalysts that are much more selective than the corresponding undoped noble metals. The catalyst activity of a Pt—Au combination, for instance, may be significantly increased by Ti and/or Zr doping while also maintaining high selectivity. Accordingly, Pt—Au—Ti, Pt—Au/TiO ₂ , Pt—Au/ZrO ₂ and Pt—Au—Ti/ZrO ₂ are all preferred embodiments of the present invention, and these are especially preferred for HTS application. These catalysts compare favorably with the known Pt—Ce MTS or Fe—Cr HTS catalysts. Pt—Au—Ti/ZrO ₂ is one preferred embodiment where, without being bound by theory, Pt is the active metal, Au enhances selectivity, and Ti and Zr function as dopants and/or carriers.

[0109] According to the invention, Pt—Au—Ir ternary catalyst was also found to be a superior WGS catalyst over both Pt alone and Pt—Au. Especially preferred WGS catalysts according to the invention may be the Pt—Au—Ir ternary series, as well as quaternary or higher order compositions, which include, but are not limited to, Pt—Au—Ir and one or more of Ti, Zr, V, Mo, Fe, Co, Ge, Sn and Ce, on supports, such as, zirconia, titania, ceria, niobia and magnesia.

[0110] Other catalyst compositions according to the invention may include Pt-Cu-Pd and Pt—Ag—Pd, which are also active catalysts for the WGS reaction.

[0111] Catalysts containing both Pt and Rh, along with Group 11 metals, may further include activity- or selectivity-enhancing promoters such as Ti, V, Mo, Fe, Co, Ge, Sn, Sb, La, Ce, Pr, Sm or Eu. Preferred carriers include, for instance, zirconia, ceria and titania. Preferred supported catalysts include, for example, Pt—Rh—Cu/ZrO ₂ , Pt—Rh—Ag/ZrO ₂ , Pt—Rh—Au/ZrO ₂ , Pt—Rh—Cu/TiO ₂ , Pt—Rh—Ag/TiO ₂ , Pt—Rh—Au/TiO ₂ , Pt—Rh—Ag—Ce/ZrO ₂ , Pt—Rh—Au—Ce/ZrO ₂ , Pt—Rh—Ag—Ti/ZrO ₂ and Pt—Rh—Au—Ti/ZrO ₂ . Note that some of the above catalyst formulations include component c) species in the support material only, and not in the impregnated components of the formulation.

[0112] D. Functional Classification of Catalyst Components

[0113] Without limiting the scope of the invention, discussion of the functions of the various catalyst components is offered, along with a template for composing catalyst compositions according to the invention. The following classification of catalyst components will direct one of skill in the art in the selection of various catalyst components to formulate WGS catalyst compositions according to the present invention and depending on the reaction conditions of interest.

[0114] Furthermore, according to the invention, there are several classes of catalyst components and metals which may be incorporated into a water gas shift catalyst. Hence, the various elements recited as components in any of the described embodiments (e.g., as component (c)), may be included in any various combination and permutation to achieve a catalyst composition that is coarsely or finely tuned for a specific application (e.g. including for a specific set of conditions, such as, temperature, pressure, space velocity, catalyst precursor, catalyst loading, catalyst surface area/presentation, reactant flow rates, reactant ratios, etc.). In some cases, the effect of a given component may vary with the operating temperature for the catalyst. These catalyst components may function as, for instance, activators or moderators depending upon their effect on the performance characteristics of the catalyst. For example, if greater activity is desired, an activator may be incorporated into a catalyst, or a moderator may be replaced by at least one activator or, alternatively, by at least one moderator one step further up the “activity ladder.” An “activity ladder” ranks secondary or added catalyst components, such as activators or moderators, in order of the magnitude of their respective effect on the performance of a principal catalyst constituent. Conversely, if WGS selectivity of a catalyst needs to be increased (e.g., decrease the occurrence of the competing methanation reaction), then either an activator may be removed from the catalyst or, alternatively, the current moderator may be replaced by at least one moderator one step down the “activity ladder.” The function of these catalyst component may be further described as “hard” or “soft” depending on the relative effect obtained by incorporating a given component into a catalyst. The catalyst components may be metals, metalloids, or non-metals.

[0115] For instance, typically, a WGS catalyst according to the invention suitable for use under LTS conditions employs activators and may only be minimally moderated, if at all, because activation is generally the important parameter to be considered under LTS conditions. Such LTS catalysts also may preferably employ high surface area carriers to enhance catalyst activity. Conversely, WGS catalysts used in HTS conditions may benefit from the catalyst being moderated because selectivity and methanation are parameters to be considered. Such HTS catalysts may use, for example, low surface area carriers. Accordingly, operating temperature may be considered in selecting a WGS catalyst according to the present invention for a particular operating environment.

[0116] Activators according to the present invention may include Ru and Co as active and selective WGS-promoting metals. Re and Pd are examples of metals that are moderately active but not very selective and also promote methanation. Ir has also been observed to have a slight moderating or activating function, depending on the presence of other counter metals. Other activators may include, but are not limited to, Ti, Zr, V, Mo, La, Ce, Pr and Eu. Ce may be the most active rare earth metal for activating the WGS reaction. La, Pr, Sm and Eu may also be active, particularly at lower temperatures. For HTS, Pr and Sm are preferred soft moderators enhancing selectivity without sacrificing much activity. For LTS, La and Eu may be useful activators. In general, all lanthanides, other than Ce, show comparable performance and tend to moderate rather than activate noble metal containing catalyst systems. Y is a highly selective moderator for HTS systems whereas La and Eu are active and comparable to Ce for LTS. La is only slightly moderating when doping Ce and may therefore be used to adjust the selectivity of Ce containing catalyst systems.

[0117] Catalyst components that are slightly moderating and highly selective over a relatively broad temperature range (e.g., a temperature range of at least about 50° C., preferably at least about 75° C., and most preferably a temperature range of at least about 100° C.), where such temperature range is included within the overall preferred temperature ranges of up to about 450° C., include Y, V, Mo, Fe, Pr and Sm; these tend to be selective but not very active at low temperatures, about 250° C. The redox dopants V, Mo, Fe, Pr and Sm generally lose activity with increasing pre-reduction temperatures while Fe becomes moderately active on its own at high WGS reaction temperatures.

[0118] Moderators may also include Cu, Ag, Au, Cd, In, Ge, Sn, Sb and Te. Typically, for moderators to exert a moderating function, they should be substantially in the reduced or metallic state. Ge alloyed with Sn is an example of an alloy that was found to be highly active, even for low temperature systems, when in the fully oxidized state, that is, when treated at a pre-reduction temperature of about 300° C. which reduces the noble metals (such as Pt, Rh or Pd) selectively but does not change the active oxidized state of the redox dopants in a catalyst composition.

[0119] E. Supports

[0120] The support or carrier may be any support or carrier used with the catalyst which allows the water gas shift reaction to proceed. The support or carrier may be a porous, adsorptive, high surface area support with a surface area of about 25 to about 500 m ² /g. The porous carrier material may be relatively inert to the conditions utilized in the WGS process, and may include carrier materials that have traditionally be utilized in hydrocarbon steam reforming processes, such as, (1) activated carbon, coke, or charcoal; (2) silica or silica gel, silicon carbide, clays, and silicates including those synthetically prepared and naturally occurring, for example, china clay, diatomaceous earth, fuller's earth, kaolin, etc.; (3) ceramics, porcelain, bauxite; (4) refractory inorganic oxides such as alumina, titanium dioxide, zirconium oxide, magnesia, etc.; (5) crystalline and amorphous aluminosilicates such as naturally occurring or synthetically prepared mordenite and/or faujasite; and, (6) combinations of these groups.

[0121] When a WGS catalyst of the invention is a supported catalyst, the support utilized may contain one or more of the metals (or metalloids) of the catalyst. The support may contain sufficient or excess amounts of the metal for the catalyst such that the catalyst may be formed by combining the other components with the support. Examples of such supports include ceria which can contribute cerium, Ce, (component c)) to a catalyst, or iron oxide which can contribute iron, Fe, (component c)). When such supports are used the amount of the catalyst component in the support typically may be far in excess of the amount of the catalyst component needed for the catalyst. Thus the support may act as both an active catalyst component and a support material for the catalyst. Alternatively, the support may have only minor amounts of a metal making up the WGS catalyst such that the catalyst may be formed by combining all desired components on the support.

[0122] Carrier screening with catalysts containing Pt as the only active noble metal revealed that a water gas shift catalyst may also be supported on a carrier comprising alumina, zirconia, titania, ceria, magnesia, lanthania, niobia, zeolite, pervoskite, silica clay, yttria and iron oxide. Perovskite (ABO ₃ ) may also be utilized as a support for the inventive catalyst formulations.

[0123] Zirconia, titania and ceria may be supports for the present invention and provide high activity for the WGS reaction. Preferably, zirconia is in the monoclinic phase. Highly pure ceria was found to activate Pt in LTS conditions more than cerias doped with additives. Niobia, yttria and iron oxide carriers provide high selectivity but are also less active which is believed to be due to a lack of surface area. Pt on magnesia carriers formulated to have high surface areas (approximately 100 m ² /g) exhibit high selectivity but also exhibit activity which decreases rapidly with falling reaction temperature.

[0124] Iron, yttrium, and magnesium oxides may be utilized as primary layers on zirconia carriers to provide both higher surface area and low moderator concentration.

[0125] In general, alumina has been found to be an active but unselective carrier for Pt only containing WGS catalysts. However, the selectivity of gamma alumina may be improved by doping with Y, Zr, Co, or one of the rare earth elements, such as, for example, La and Ce. This doping may be accomplished by addition of the oxides or other salts such as nitrates, in either liquid or solid form, to the alumina. Other possible dopants to increase the selectivity include redox dopants, such as for instance, Re, Mo, Fe, and basic dopants. Preferred is an embodiment of gamma alumina combined with yttria or with both Zr and/or Co which exhibit both high activity and selectivity over a broad temperature range.

[0126] High surface area aluminas, such as gamma-, delta-, or theta-alumina are preferred alumina carriers. Other alumina carriers, such as mixed silica alumina, sol-gel alumina, as well as sol-gel or co-precipitated alumina-zirconia carriers may be used. Alumina typically has a higher surface area and a higher pore volume than carriers such as zirconia and offers a price advantage over other more expensive carriers.

[0127] F. Methods of Making a WGS Catalyst

[0128] As set forth above, a WGS catalyst of the invention may be prepared by mixing the metals and/or metalloids in their elemental forms or as oxides or salts to form a catalyst precursor, which generally undergoes a calcination and/or reductive treatment. Without being bound by theory, the catalytically active species are generally understood to be species which are in the reduced elemental state or in other possible higher oxidation states.

[0129] The WGS catalysts of the invention may be prepared by any well known catalyst synthesis processes. See, for example, U.S. Pat. Nos. 6,299,995 and 6,293,979. Spray drying, precipitation, impregnation, incipient wetness, ion exchange, fluid bed coating, physical or chemical vapor deposition are just examples of several methods that may be utilized to make the present WGS catalysts. Preferred approaches, include, for instance, impregnation or incipient wetness. The catalyst may be in any suitable form, such as, pellets, granular, bed, or monolith. See also the co-pending U.S. patent application Ser. No. ______ filed on the same date as the present application titled “Methods For The Preparation Of Catalysts For Hydrogen Generation” to Hagemeyer et al. under Attorney Docket No. 7080-011-01 for further details on methods of catalyst preparation and catalyst precursors. The complete disclosure of the above mentioned application and all other references cited herein are incorporated herein in their entireties for all purposes.

[0130] The WGS catalyst of the invention may be prepared on a solid support or carrier material. Preferably, the support or carrier is, or is coated with, a high surface area material onto which the precursors of the catalyst are added by any of several different possible techniques, as set forth above and as known in the art. The catalyst of the invention may be employed in the form of pellets, or on a support, preferably a monolith, for instance a honeycomb monolith.

[0131] Catalyst precursor solutions are preferably composed of easily decomposable forms of the catalyst component in a sufficiently high enough concentration to permit convenient preparation. Examples of easily decomposable precursor forms include the nitrate, amine, and oxalate salts. Typically chlorine-containing precursors are avoided to prevent chlorine poisoning of the catalyst. Solutions can be aqueous or non-aqueous solutions. Exemplary non-aqueous solvents can include polar solvents, aprotic solvents, alcohols, and crown ethers, for example, tetrahydrofuran, and ethanol. Concentration of the precursor solutions generally may be up to the solubility limitations of the preparation technique with consideration given to such parameters as, for example, porosity of the support, number of impregnation steps, pH of the precursor solutions, and so forth. The appropriate catalyst component precursor concentration can be readily determined by one of ordinary skill in the art of catalyst preparation.

[0132] Li—The acetate, hydroxide, nitrate and formate salts are both possible catalyst precursors for lithium.

[0133] Na—Sodium acetate, alkoxides including methoxide, propoxide, and ethoxide, bicarbonate, carbonate, citrate, formate, hydroxide, nitrate, nitrite and oxalate may be used to prepare WGS catalysts of the invention.

[0134] Mg—Water soluble magnesium precursors include the nitrate, acetate, lactate and formate salts.

[0135] K—Potassium nitrate, acetate, carbonate, hydroxide and formate are possible potassium catalyst precursors. The KOAc salt is volatile with possible potassium losses when heating up to calcination temperature.

[0136] Ca—The nitrate, acetate and hydroxide salts, preferable salts highly soluble in water, may be used to prepare catalysts of the invention.

[0137] Sc—The nitrate salt, Sc(NO ₃ ) ₃ may be a precursor for scandium.

[0138] Ti—Titanium precursors which may be utilized in the present invention include ammonium titanyl oxalate, (NH ₄ ) ₂ TiO(C ₂ O ₄ ) ₂ , available from Aldrich, and titanium(IV) bis(ammonium lactato)dihydroxide, 50 wt. % solution in water,

[0139] [CH ₃ CH(O—)CO ₂ NH ₄ ] ₂ Ti(OH) ₂ , available from Aldrich. Other titanium containing precursors include Ti oxalate prepared by dissolving a Ti(IV) alkoxide, such as Ti(IV) propoxide, Ti(OCH ₂ CH ₂ CH ₃ ) ₄ , (Aldrich) in 1M aqueous oxalic acid at 60° C. and stirring for a couple of hours, to produce a 0.72M clear colorless solution; TiO(acac)oxalate prepared by dissolving Ti(IV) oxide acetylacetonate, TiO(acac) ₂ , (Aldrich) in 1.5M aqueous oxalic acid at 60° C. with stirring for a couple of hours, following by cooling to room temperature overnight to produce 1M clear yellow-brown solution; TiO(acac) ₂ , may also be dissolved in dilute acetic acid (50:50 HOAc:H ₂ O) at room temperature to produce a 1M clear yellow solution of TiO-acac. Preferably, titanium dioxide in the anatase form is utilized as a catalyst precursor material.

[0140] V—Vanadium (IV) oxalate, a vanadium precursor, may be prepared from V ₂ O ₅ , (Aldrich), which is slurried in 1.5M aqueous oxalic acid on hot plate for 1 hour until it turns dark blue due to V(V) reduction to V(IV) by oxalic acid. Ammonium metavanadate(V), (NH ₄ )VO ₃ , (Cerac, Alfa) may be used as a precursor by dissolving it in water, preferably hot, about 80° C. water. Various polycarboxylic organic acid vanadium precursors can be prepared and used as catalyst precursors, for example, citric, maleic, malonic, and tatartic. Vanadium citrate can be prepared by reacting V ₂ O ₅ with citric acid, and heating to about 80° C. Ammonium vanadium(V) oxalate may be prepared by reacting (NH ₄ )VO ₃ and NH ₄ OH in room temperature water, increasing temperature to 90° C., stirring to dissolve all solids, cooling to room temperature and adding oxalic acid; this produces a clear orange solution, which is stable for about 2 days. Ammonium vanadium(V) citrate and ammonium vanadium(V) lactate are both prepared by shaking NH ₄ VO ₃ in, respectively, aqueous citric acid or aqueous lactic acid, at room temperature. Diammonium vanadium(V) citrate may be prepared by dissolving, for instance, 0.25M NH ₄ VO ₃ in citric acid diammonium salt (Alfa) at room temperature. An exemplary method of preparing ammonium vanadium(V) formate is to dissolve NH ₄ VO ₃ (0.25M) in water at 95° C., react with 98% formic acid and NH ₄ OH to produce the desired ammonium vanadium(V) formate.

[0141] Cr—Both the nitrate and acetate hydroxides are possible catalyst precursors for chromium.

[0142] Mn—Manganese nitrate, manganese acetate (Aldrich) and manganese formate (Alfa) are all possible catalyst precursors for manganese.

[0143] Fe—Iron (III) nitrate, Fe(NO ₃ ) ₃ , iron(III) ammonium oxalate, (NH ₄ ) ₃ Fe(C ₂ O ₄ ) ₃ , iron(III) oxalate, Fe ₂ (C ₂ O ₄ ) ₃ , and iron(II) acetate, Fe(OAc) ₂ , are all water although the iron(III)oxalate undergoes thermal decomposition at only 100° C. Potassium iron(III) oxalate, iron(III) formate and iron(III) citrate are additional iron precursors.

[0144] Co—Both cobalt nitrate and acetate are water soluble precursor solutions. The cobalt (II) formate, Co(OOCH) ₂ , has low solubility in cold water of about 5 g/100 ml, while cobalt (II) oxalate is soluble in aqueous NH ₄ OH. Another possible precursor is sodium hexanitrocobaltate(II), Na ₃ Co(NO ₂ ) ₆ which is water soluble, with gradual decomposition of aqueous solutions slowed by addition of small amounts of acetic acid. Hexaammine Co(III) nitrate is also soluble in hot (65° C.) water and NMe ₄ OH. Cobalt citrate, prepared by dissolving Co(OH) ₂ in aqueous citric acid at 80° C. for 1 to 2 hours, is another suitable cobalt precursor.

[0145] Ni—Nickel nitrate, Ni(NO ₃ ) ₂ , and nickel formate are both possible nickel precursors. The nickel formate may be prepared by dissolving Ni(HCO ₂ ) ₂ in water and adding formic acid, or by dissolving in dilute formic acid, to produce clear greenish solutions. Nickel acetate, Ni(OAc) ₂ , is also a nickel precursor. Nickel chloride, NiCl ₂ , may also be used when precipitating nickel salts such as nickel hydroxide or nickel carbonate. In contrast to catalyst compositions containing noble metals, base metal catalysts, such as bulk Ni, are not poisoned by chloride.

[0146] Cu—Copper precursors include nitrate, Cu(NO ₃ ) ₂ , acetate, Cu(OAc) ₂ , and formate, Cu(OOCH) ₂ , which are increasingly less water soluble in the order presented. Ammonium hydroxide is used to solublize oxalate, Cu(C ₂ O ₄ ) ₂ , and Cu(NH ₃ ) ₄ (OH) ₂ which is soluble in aqueous SN NH ₄ OH. Copper citrate and copper amine carbonate may be prepared from Cu(OH) ₂ .

[0147] Zn—Zinc nitrate, acetate and formate are all water soluble and possible catalyst precursors. Ammonium zinc carbonate, (NH ₄ ) ₂ Zn(OH) ₂ CO ₃ , prepared by reacting zinc hydroxide and ammonium carbonate for a week at room temperature, is another possible precursor for zinc.

[0148] Ge—Germanium oxalate may be prepared from amorphous Ge(IV) oxide, glycol-soluble GeO ₂ , (Aldrich) by reaction with 1M aqueous oxalic acid at room temperature. H ₂ GeO ₃ may be prepared by dissolving GeO ₂ in water at 80° C. and adding 3 drops of NE ₄ OH (25%) to produce a clear, colorless H ₂ GeO ₃ solution. (NMe ₄ ) ₂ GeO ₃ may be prepared by dissolving 0.25M GeO ₂ in 0.1 M NMe ₄ OH. (NH ₄ ) ₂ GeO ₃ may be prepared by dissolving 0.25 M GeO ₂ in 0.25M NH ₄ OH.

[0149] Rb—The nitrate, acetate, carbonate and hydroxide salts may be used as catalyst precursors to prepare the WGS catalyst of the invention. Preferred are water soluble salts.

[0150] Sr—The acetate is soluble in cold water to produce a clear colorless solution.

[0151] Y—Yttrium nitrate and acetate are both possible catalyst precursors.

[0152] Zr—Zirconyl nitrate and acetate, commercially available from Aldrich, and ammonium Zr carbonate and zirconia, available from MEI, are possible precursors for zirconium in either or both the support or catalyst formulation itself

[0153] Nb—Niobium oxalate prepared by dissolving niobium (V) ethoxide in aqueous oxalic acid at 60° C. for 12 hours is a possible catalyst precursor. Another preparative route to the oxalate is dissolving niobic acid or niobic oxide (Nb ₂ O ₅ ) in oxalic acid at 65° C. Ammonium Nb oxalate is also a possible catalyst precursor for niobium. Dissolving niobic oxide (0.10M Nb) in NMe ₄ OH (0.25M) and stirring overnight at 65° C. will produce (NMe ₄ ) ₂ NbO ₆ .

[0154] Mo—Molybdenum containing precursor solutions may be derived from ammonium molybdate (NH ₄ ) ₂ MoO ₄ (Aldrich) dissolved in room temperature water; Mo oxalate prepared by dissolving MoO ₃ (Aldrich) in 1.5M aqueous oxalic acid at 60° C. overnight; and ammonium Mo oxalate prepared from (NH ₄ ) ₆ Mo ₇ O ₂₄ .4H ₂ O (Strem) dissolved in 1M aqueous oxalic acid at room temperature. (NH ₄ ) ₆ Mo ₇ O ₂₄ .4H ₂ O (Strem) may also be dissolved in water at room temperature to produce a stable solution of ammonium paramolybdate tetrahydrate. Molybdic acid, H ₂ MoO ₄ , (Alfa Aesar or Aldrich) may each be dissolved in room temperature water to produce 1M Mo containing solutions.

[0155] Ru—Ru nitrosyl nitrate, Ru(NO)(NO ₃ ) ₃ (Aldrich), potassium ruthenium oxide, K ₂ RuO ₄ H ₂ O, potassium perruthenate, KRuO ₄ , ruthenium nitrosyl acetate, Ru(NO)(OAc) ₃ , and tetrabutylammonium perruthenate, NBu ₄ RuO ₄ , are all possible ruthenium metal catalyst precursors. NMe ₄ Ru(NO)(OH) ₄ solution can be prepared by dissolving Ru(NO)(OH) ₃ (0.1 M) (H. C. Starck) in NMe ₄ OH (0.12M) at 80° C. produces a clear dark red-brown 0.1M Ru solution useful as a catalyst precursor solution.

[0156] Rh—A suitable rhodium catalyst precursor is Rh nitrate (Aldrich or Strem).

[0157] Pd—Catalyst compositions containing Pd can be prepared by using precursors like Pd nitrate, typically stabilized by dilute HNO ₃ , and available as a 10 wt. % solution from Aldrich, or Pd(NH ₃ ) ₂ (NO ₂ ) ₂ available as a 5 wt. % Pd commercial solution, stabilized by dilute NH ₄ OH. Pd( ₃ ) ₄ (NO ₃ ) ₂ and Pd( ₃ ) ₄ (OH) ₂ are also available commercially.

[0158] Ag—Silver nitrate, silver nitrite, silver diammine nitrite, and silver acetate are possible silver catalyst precursors.

[0159] Cd—Cadmium nitrate is water soluble and a suitable catalyst precursor.

[0160] In—Indium formate and indium nitrate are preferred precursors for indium.

[0161] Sn—Tin oxalate produced by reacting the acetate with oxalic acid may be used as a catalyst precursor. Tin tartrate, SnC ₄ H ₄ O ₆ , in NMe ₄ OH at about 0.25M Sn concentration, and tin actetate, also dissolved in NMe ₄ OH at about 0.25M Sn concentration, may be used as catalyst precursors.

[0162] Sb—Ammonium antimony oxalate produced by reacting the acetate with oxalic acid and ammonia is a suitable antimony precursor. Antimony oxalate, Sb ₂ (C ₂ O ₄ ) ₃ , available from Pfaltz & Bauer, is a water soluble precursor. Potassium antimony oxide, KSbO ₃ , and antimony citrate, prepared by stirring antimony(II) acetate in 1M citric acid at room temperature, are both possible catalyst precursors.

[0163] Te—Telluric acid, Te(OH) ₆ , may be used as a precursor for tellurium.

[0164] Cs—Cs salts including the nitrate, acetate, carbonate, and hydroxide are soluble in water and possible catalyst precursors.

[0165] Ba—Barium acetate and barium nitrate are both suitable precursors for barium catalyst components.

[0166] La—Lanthanum precursors include nitrate, La(NO ₃ ) ₃ , acetate, La(OAc) ₃ , and perchlorate, La(ClO ₄ ) ₃ , all of which may be prepared as aqueous solutions.

[0167] Ce—Ce(III) and Ce(IV) solutions may be prepared from Ce(III) nitrate hexahydrate, Ce(NO ₃ ) ₃ .6H ₂ O, (Aldrich) and ammonium cerium(IV) nitrate, (NH ₄ ) ₂ Ce(NO ₃ ) ₆ , (Aldrich), respectively, by dissolution in room temperature water. Nitric acid, 5 vol. %, may be added to the Ce(III) salt to increase solubility and stability. Ce(OAc) ₃ (Alfa) or Ce(NO ₃ ) ₄ (Alfa) may also be utilized as a catalyst precursor.

[0168] Pr, Nd, Sm and Eu—The nitrate, Ln(NO ₃ ) ₃ , or acetate, Ln(O ₂ CCH ₃ ) ₃ , are possible catalyst precursors for these lanthanides.

[0169] Hf—Hafnoyl chloride and nitrate are both possible precursors. Preparing the hafnoyl nitrate by dissolving Hf(acac) ₄ in dilute HNO ₃ at low heat provides a clear stable solution of hafnoyl nitrate.

[0170] Ta—Tantalum oxalate solution, Ta ₂ O(C ₂ O ₄ ) ₄ , available from H. C. Starck, or prepared by dissolving Ta(OEt) ₅ in aqueous oxalic acid at 60° C. for 12 hours, is a possible catalyst precursor.

[0171] W—Ammonium metatungstate hydrate, (NH ₄ ) ₆ W ₁₂ O ₃₉ , is water soluble and a possible tungsten catalyst precursor. H ₂ WO ₄ is reacted with NH ₄ OH and NMe ₄ OH, respectively, to prepare (NH ₄ ) ₂ WO ₄ and (NMe ₄ ) ₂ WO ₄ which are both possible precursors.

[0172] Re—Rhenium oxide in H ₂ O ₂ , perrhenic acid, (HReO4), NaReO ₄ and NH ₄ ReO ₄ are suitable rhenium precursors.

[0173] Ir—Hexachloroiridate acid, H ₂ IrCl ₆ , potassium hexacyanoiridate and potassium hexanitroiridate are all possible catalyst precursors for iridium.

[0174] Pt—Platinum containing catalyst compositions may be prepared by using any one of a number of precursor solutions, such as, Pt(NH ₃ ) ₄ (NO ₃ ) ₂ (Aldrich, Alfa, Heraeus, or Strem), Pt(NH ₃ ) ₂ (NO ₂ ) ₂ in HNO ₃ , Pt(NH ₃ ) ₄ (OH) ₂ (Alfa), K ₂ Pt(NO ₂ ) ₄ , Pt(NO ₃ ) ₂ , PtCl ₄ and H ₂ PtCl ₆ (chloroplatinic acid). Pt(NH ₃ ) ₄ (HCO ₃ ) ₂ , Pt(NH ₃ ) ₄ (HPO ₄ ), (NMe ₄ ) ₂ Pt(OH) ₆ , H ₂ Pt(OH) ₆ , K ₂ Pt(OH) ₆ , Na ₂ Pt(OH) ₆ and K ₂ Pt(CN) ₆ are also possible choices along with Pt oxalate salts, such as K ₂ Pt(C ₂ O ₄ ) ₂ . The Pt oxalate salts may be prepared from Pt(NH ₃ ) ₄ (OH) ₂ which is reacted with 1M oxalic acid solution to produce a clear, colorless solution of the desired Pt oxalate salts.

[0175] Au—Auric acid, HAuCl ₄ , in dilute HCl at about 5% Au may be a gold precursor. Gold nitrate in 0.1M concentration may be prepared by dissolving HAu(NO ₃ ) ₄ (Alfa) in concentrated nitric acid, followed by stirring at room temperature for 1 week in the dark, then diluting 1:1 with water to produce a yellow solution. It should be noted that further dilution may result in Au precipitation. More concentrated, 0.25M, for example, gold nitrate may be prepared by starting with Au(OH) ₃ (Alfa). NaAu(OH) ₄ , KAu(OH) ₄ , and NMe ₄ Au(OH) ₄ may each be prepared from Au(OH) ₃ dissolved in bases NaOH, KOH, or NMe ₄ OH, respectively, in base concentrations ranging from, for instance, 0.25M or higher.

[0176] 3. Producing a Hydrogen-Rich Gas, Such As, a Hydrogen-Rich Syngas

[0177] The invention also relates to a method for producing a hydrogen-rich gas, such as a hydrogen-rich syngas. An additional embodiment of the invention may be directed to a method of producing a CO depleted gas, such as a CO-depleted syngas.

[0178] A CO-containing gas, such as a syngas contacts with a water gas shift catalyst in the presence of water according to the method of the invention. The reaction preferably may occur at a temperature of less than 450° C. to produce a hydrogen-rich gas such as a hydrogen-rich syngas.

[0179] A method of the invention may be utilized over a broad range of reaction conditions. Preferably, the method is conducted at a pressure of no more than about 75 bar, preferably at a pressure of no more than about 50 bar to produce a hydrogen-rich syngas. Even more preferred is to have the reaction occur at a pressure of no more than about 25 bar, or even no more than about 15 bar, or not more than about 10 bar. Especially preferred is to have the reaction occur at, or about atmospheric pressure. Depending on the formulation of the catalyst according to the present invention, the present method may be conducted at reactant gas temperatures ranging from less than about 250° C. to up to about 450° C. Preferably, the reaction occurs at a temperature selected from one or more temperature subranges of LTS, MTS and/or HTS as described above. Space velocities may range from about 1 hr ⁻¹ up to about 1,000,000 hr ¹ . Feed ratios, temperature, pressure and the desired product ratio are factors that would normally be considered by one of skill in the art to determine a desired optimum space velocity for a particular catalyst formulation.

[0180] 4. Fuel Processor Apparatus

[0181] The invention further relates to a fuel processing system for generation of a hydrogen-rich gas from a hydrocarbon or substituted hydrocarbon fuel. Such a fuel processing system would comprise, for example, a fuel reformer, a water gas shift reactor and a temperature controller.

[0182] The fuel reformer would convert a fuel reactant stream comprising a hydrocarbon or a substituted hydrocarbon fuel to a reformed product stream comprising carbon monoxide and water. The fuel reformer may typically have an inlet for receiving the reactant stream, a reaction chamber for converting the reactant stream to the product stream, and an outlet for discharging the product stream.

[0183] The fuel processor system would also comprise a water gas shift reactor for effecting a water gas shift reaction at a temperature of less than about 450° C. This water gas shift reactor may comprise an inlet for receiving a water gas shift feed stream comprising carbon monoxide and water from the product stream of the fuel reformer, a reaction chamber having a water gas shift catalyst as described herein located therein, and an outlet for discharging the resulting hydrogen-rich gas. The water gas shift catalyst would preferable be effective for generating hydrogen and carbon dioxide from the water gas shift feed stream.

[0184] The temperature controller may be adapted to maintain the temperature of the reaction chamber of the water gas shift reactor at a temperature of less than about 450° C.

[0185] 5. Industrial Applications

[0186] Syngas is used as a reactant feed in number of industrial applications, including for example, methanol synthesis, ammonia synthesis, oxoaldehyde synthesis from olefins (typically in combination with a subsequent hydrogenation to form the corresponding oxoalcohol), hydrogenations and carbonylations. Each of these various industrial applications preferably includes a certain ratio of H ₂ to CO in the syngas reactant stream. For methanol synthesis the ratio of H ₂ :CO is preferably about 2: 1. For oxosynthesis of oxoaldehydes from olefins, the ratio of H ₂ :CO is preferably about 1: 1. For ammonia synthesis, the ratio of H ₂ to N ₂ (e.g., supplied from air) is preferably about 3:1. For hydrogenations, syngas feed streams that have higher ratios of H ₂ :CO are preferred (e.g., feed streams that are H ₂ enriched, and that are preferably substantially H ₂ pure feed streams). Carbonylation reactions are preferably effected using feed streams that have lower ratios of H ₂ :CO (e.g., feed streams that are CO enriched, and that are preferably substantially CO pure feed streams).

[0187] The WGS catalysts of the present invention, and the methods disclosed herein that employ such WGS catalysts, can be applied industrially to adjust or control the relative ratio H ₂ :CO in a feed stream for a synthesis reaction, such as methanol synthesis, ammonia synthesis, oxoaldehyde synthesis, hydrogenation reactions and carbonylation reactions. In one embodiment, for example, a syngas product stream comprising CO and H ₂ can be produced from a hydrocarbon by a reforming reaction in a reformer (e.g., by steam reforming of a hydrocarbon such as methanol or naphtha). The syngas product stream can then be fed (directly or indirectly after further downstream processing) as the feed stream to a WGS reactor, preferably having a temperature controller adapted to maintain the temperature of the WGS reactor at a temperature of about 450° C. or less during the WGS reaction (or at lower temperatures or temperature ranges as described herein in connection with the catalysts of the present invention). The WGS catalyst(s) employed in the WGS reactor are preferably selected from one or more of the catalysts and/or methods of the invention. The feed stream to the WGS reactor is contacted with the WGS catalyst(s) under reaction conditions effective for controlling the ratio of H ₂ :CO in the product stream from the WGS reactor (i.e., the “shifted product stream”) to the desired ratio for the downstream reaction of interest (e.g, methanol synthesis), including to ratios described above in connection with the various reactions of industrial significance. As a non-limiting example, a syngas product stream from a methane steam reformer will typically have a H ₂ :CO ratio of about 6:1. The WGS catalyst(s) of the present invention can be employed in a WGS reaction (in the forward direction as shown above) to further enhance the amount of H ₂ relative to CO, for example to more than about 10:1, for a downstream hydrogenation reaction. As another example, the ratio of H ₂ :CO in such a syngas product stream can be reduced by using a WGS catalyst(s) of the present invention in a WGS reaction (in the reverse direction as shown above) to achieve or approach the desired 2:1 ratio for methanol synthesis. Other examples will be known to a person of skill in the art in view of the teachings of the present invention.

[0188] A person of skill in the art will understand and appreciate that with respect to each of the preferred catalyst embodiments as described in the preceding paragraphs, the particular components of each embodiment can be present in their elemental state, or in one or more oxide states, or mixtures thereof

[0189] Although the foregoing description is directed to the preferred embodiments of the invention, it is noted that other variations and modifications will be apparent to those skilled in the art, and which may be made without departing from the spirit or scope of the invention.

EXAMPLES

[0190] General

[0191] Small quantity catalyst composition samples are generally prepared by automated liquid dispensing robots (Cavro Scientific Instruments) on flat quartz test wafers.

[0192] Generally, supported catalysts are prepared by providing a catalyst support (e.g. alumina, silica, titania, etc.) to the wafer substrate, typically as a slurry composition using a liquid-handling robot to individual regions or locations on the substrate or by wash-coating a surface of the substrate using techniques known to those of skill in the art, and drying to form dried solid support material on the substrate. Discrete regions of the support-containing substrate are then impregnated with specified compositions intended to operate as catalysts or catalyst precursors, with the compositions comprising metals (e.g. various combinations of transition metal salts). In some circumstances the compositions are delivered to the region as a mixture of different metal-containing components and in some circumstances (additionally or alternatively) repeated or repetitive impregnation steps are performed using different metal-containing precursors. The compositions are dried to form supported catalyst precursors. The supported catalyst precursors are treated by calcining and/or reducing to form active supported catalytic materials at discrete regions on the wafer substrate.

[0193] Bulk catalysts (e.g. noble-metal-free Ni-containing catalysts) may also be prepared on the substrate. Such multi-component bulk catalysts are purchased from a commercial source and/or are prepared by precipitation or co-precipitation protocols, and then optionally treated—including mechanical pretreatment (grinding, sieving, pressing). The bulk catalysts are placed on the substrate, typically by slurry dispensing and drying, and then optionally further doped with additional metal-containing components (e.g. metal salt precursors) by impregnation and/or incipient wetness techniques to form bulk catalyst precursors, with such techniques being generally known to those of skill in the art. The bulk catalyst precursors are treated by calcining and/or reducing to form active bulk catalytic materials at discrete regions on the wafer substrate.

[0194] The catalytic materials (e.g., supported or bulk) on the substrate are tested for activity and selectivity for the WGS reaction using a scanning mass spectrometer (“SMS”) comprising a scanning/sniffing probe and a mass spectrometer. More details on the scanning mass spectrometer instrument and screening procedure are set forth in U.S. Pat. No. 6,248,540, in European Patent No. EP 1019947 and in European Patent Application No. EP 1186892 and corresponding U.S. application Ser. No. 09/652,489 filed Aug. 31, 2000 by Wang et al., the complete disclosure of each of which is incorporated herein in its entirety. Generally, the reaction conditions (e.g. contact time and/or space velocities, temperature, pressure, etc.) associated with the scanning mass spectrometer catalyst screening reactor are controlled such that partial conversions (i.e., non-equilibrium conversions, e.g., ranging from about 10% to about 40% conversion) are obtained in the scanning mass spectrometer, for discrimination and ranking of catalyst activities for the various catalytic materials being screened. Additionally, the reaction conditions and catalyst loadings are established such that the results scale appropriately with the reaction conditions and catalyst loadings of larger scale laboratory research reactors for WGS reactions. A limited set of tie-point experiments are performed to demonstrate the scalability of results determined using the scanning mass spectrometer to those using larger scale laboratory research reactors for WGS reactions. See, for example, Example 12 of U.S. Provisional Patent Application Ser. No. 60/434,708 entitled “Platinum-Ruthenium Containing Catalyst Formulations for Hydrogen Generation” filed by Hagemeyer et al on Dec. 20, 2002.

[0195] Preparative and Testing Procedures

[0196] The catalysts and compositions of the present invention were identified using high-throughput experimental technology, with the catalysts being prepared and tested in library format, as described generally above, and in more detail below. Specifically, such techniques were used for identifying catalyst compositions that were active and selective as WGS catalysts. As used in these examples, a “catalyst library” refers to an associated collectio