CO2 hydrogenation catalysts for the commercial production of syngas

Abstract

The present invention is generally directed to the production of low-carbon syngas from captured CO.sub.2 and renewable H.sub.2. The H.sub.2 is generated from water using an electrolyzer powered by renewable electricity, or from any other method of low-carbon H.sub.2 production. The improved catalysts use low-cost metals, they can be produced economically in commercial quantities, and they are chemically and physically stable up to 2,100° F. CO.sub.2 conversion is between 80% and 100% with CO selectivity of greater than 99%. The catalysts don't sinter or form coke when converting H.sub.2:CO.sub.2 mixtures to syngas in the operating ranges of 1,300-1,800° F., pressures of 75-450 psi, and space velocities of 2,000-100,000 hr.sup.−1. The catalysts are stable, exhibiting between 0 and 1% CO.sub.2 conversion decline per 1,000 hrs. The syngas can be used for the synthesis of low-carbon fuels and chemicals, or for the production of purified H.sub.2. The H.sub.2 can be used at the production site for the synthesis of low-carbon chemical products or compressed for transportation use.

Claims

1. A catalyst for the production of syngas, where the catalyst comprises: a chemical composition which contains no precious metals chosen from the group Rh, Pt, Au, Ag, Pd, or Ir; wherein the catalyst has a hardness of between 4 Mohs and 10 Mohs; wherein the catalyst is chemically and physically stable at temperatures of 2,100° F. such that after a thermal treatment at 2,100° F., the BET surface area of the catalyst is between 0 and 20% of the pre-treatment surface area; wherein the catalyst can be loaded readily into catalytic reactors where the pressure drop from the inlet to the outlet of the catalytic reactor is between 0 and 50 psi; wherein the catalyst can convert CO.sub.2 to CO where the CO.sub.2 conversion is between 70% and 100% at a temperature between 1,300° F. and 1,800° F. and pressures above 50 psi and wherein the catalyst does not coke during the conversion, and wherein the CO.sub.2 conversion declines by between 0 and 1% per 1000 hours of operation.

2. The catalyst of claim 1 where the catalyst comprises a metal alumina spinel.

3. The catalyst of claim 2 wherein the metal alumina spinel is produced from the calcining of a mixture of alumina with at least one of the elements chosen from the following group consisting of at least one of the following elements—Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce.

4. The catalyst of claim 2 wherein the metal alumina spinel is impregnated with one or more metals selected from the Alkali Metals, the Alkaline Earth Metals, the Transition Metals, and the Rare-Earth metals.

5. The catalyst of claim 4 wherein one of the metals that is impregnated on the metal-impregnated metal-alumina spinel is selected from the group of Ni, Co, Fe, Cu, La, Ce, Zr, Ti, La, Li, Cs, Rb, Mg, Ca, Sr, Ba, Be and where the catalyst is calcined up to 2,100° F. to form a solid solution on the metal alumina spinel.

6. The catalyst of claim 4 wherein the impregnation of metals on the metal-aluminate is from 0.0 to 35 wt. % of a metal salt or metal hydroxides selected from a group comprising Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce; and calcining the impregnated, metal-coated metal-alumina spinel at a temperature up to 2,100° F., thereby synthesizing a catalyst that is an metal-impregnated, metal-alumina spinel.

7. The catalyst of claim 4 wherein the metal impregnated metal-alumina spinel has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

8. The catalyst of claim 1 wherein the catalyst comprises an hydrotalcite.

9. The catalyst of claim 1 wherein the catalyst comprises a layered double hydroxide.

10. The catalyst of claim 8 which has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

11. The catalyst of claim 9 which has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

12. The catalyst of claim 1 which has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

13. The catalyst of claim 12 which comprises a perovskite having the general composition ABO.sub.3 where A is selected from the group consisting of Sr, Ca, Ba, Mg, Fe, La, Ca, Pb, or Bi and B is selected from Al, Ti, Rb, Si, Fe, Yb or Mn.

14. The catalyst of claim 12 which comprised a spinel having the general composition of AB.sub.2O.sub.4 where A is selected from the group consisting of Mg, Zn, Fe, Mn, Cu, Ni, Li, Cs, Rb, Mg, Ca, Sr, Ba, Be, and Ti and B is selected from the group consisting of aluminum, iron, chromium, cobalt, and vanadium.

15. The catalyst of claim 14 where the catalyst comprises a metal aluminate where B is aluminum.

16. A process for the production of syngas comprising: reacting a feedstock comprising a mixture of hydrogen and carbon dioxide in a catalytic reactor including a catalyst, wherein the catalyst comprises the following: a chemical composition which contains no precious metals chosen from the group Rh, Pt, Au, Ag, Pd, or Ir, wherein the catalyst has a hardness of between 4 Mohs and 10 Mohs, wherein the catalyst is chemically and physically stable at temperatures of 2,100° F. such that after a thermal treatment at 2,100° F., the BET surface area of the catalyst is within between 0 and 5% of the pre-treatment surface area, wherein the catalyst can be loaded readily into catalytic reactors where the pressure drop from the inlet to the outlet of the catalytic reactor is between 0 and 50 psi, wherein the catalyst can convert CO.sub.2 to CO where the CO.sub.2 conversion is between 70% and 100% at a temperature between 1,300° F. and 1,800° F. and pressures above 50 psi and wherein the catalyst does not coke and during the conversion, and wherein CO.sub.2 conversion declines by between 0 and 1% per 1000 hours of operation, where the catalytic reactor is operated between 1,300° F. and 1,800° F. at a pressure from 50 psi to 450 psi, thereby producing a product stream from the catalytic reactor comprising CO.

17. The process of claim 16 where the feedstock comprises H.sub.2/CO.sub.2 ratio of 1.5 to 4.0.

18. The process of claim 16 where the catalyst does not coke.

19. The process of claim 16 in wherein the catalytic reactor is operated at temperatures between 1,300° F. and 1,800° F.

20. The process of claim 16 wherein the product stream is further reacted to produce at least one of the following products chosen from the list consisting of liquid fuels, methanol, propane, naphtha, and chemicals

Description

BRIEF DESCRIPTION OF THE DRAWING

[0033] FIG. 1 describes the typical relationship of temperature with CO.sub.2 conversion to CO using the improved catalysts of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0034] In this section we describe our improved catalyst formulations which has been demonstrated to meet the performance and quality requirements presented in Table 1.

[0035] Four types of improved CO.sub.2 hydrogenation or Reverse Water Gas Shift (RWGS) catalysts are described in these embodiments.

[0036] Type A. Metal-Spinel Catalysts—Pure alumina is an amphoteric substance, as it can react with both acids and bases. Depending on the morphology and crystal structure present the basicity of alumina can be complex. Acidic alumina catalyzes reactions that are typically acid catalyzed (Pines et al, 1960). However, several spinels produced from the high-temperature calcination of alumina with the Group 1 metals (Li, Cs, Rb) and Group 2 metals (Mg, Ca, Sr, Ba and Be) form metal aluminates that have defined and usually basic surface properties, also due to the increased surface concentrations of the hydroxy (—OH) groups.

[0037] Formates are formed when H.sub.2/CO.sub.2 mixtures react with these hydroxy groups according to Equation 2.

H.sub.2+CO.sub.2═HCOO-Metal Aluminate+H.sub.2O  (Eq. 2)

[0038] These formates decompose rapidly at high temperatures in the presence of H.sub.2 to form CO (Equation 3) with a high selectivity. Therefore, some of these spinels are excellent CO.sub.2 hydrogenation catalysts.

2HCOO-Metal Aluminate+H.sub.2=2CO+2H.sub.2O  (Eq. 3)

[0039] A spinel of the invention is any class of minerals or synthetically produced minerals with the general chemical form of AB.sub.2X.sub.4. For the invention, X is oxygen, B can be chosen from the group comprising aluminum, iron, chromium, cobalt, and vanadium. A is chosen from a group comprising Mg, Zn, Fe, Mn, Cu, Ni, Li, Cs, Rb, Mg, Ca, Sr, Ba, Be, and Ti. In one embodiment of the invention, the catalyst is a metal aluminate such that B is Aluminum, and X is Oxygen.

[0040] Type B. Metal Impregnated Metal-Spinel Catalysts—When selected Group 1 (alkali metals such as Li, Cs, Rb) and/or Group 2 (alkaline earth metals such as Mg, Ca, Sr, Ba, and Be) are impregnated on selected spinels in the appropriate levels, the surface abundance of hydroxy groups increases, resulting in their improved efficiency for CO.sub.2 hydrogenation. The addition of these elements is believed to enhance the chemisorption of CO.sub.2 due to their impact on basicity, total pore volume and surface are. Dopants may be Ni, Cu, Ce, Zr, Ti, La, or the early Lanthanides. When two or more impregnated metals on the metal aluminate spinel are calcined up to a temperature of 2,100° F., a solid solution is formed. This solid solution represents excellent catalyst for CO.sub.2 hydrogenation. Ni and Mg form a solid solution, Ni.sub.2Mg, at 2,050° F. on Mg-Aluminate since Ni and Mg both crystallize in a face-centered cubic structure, and they have similar electronegativities and valences. Ni also forms a solid solution with Cu, NiCu.sub.3, at 2,050° F. since Ni and Cu both crystallize in a face-centered cubic structure, and they have similar atomic radii, electronegativities and valences. Solid solutions are formed when two of the metals impregnated on the metal aluminate spinel have similar crystal structures, atomic radii, electronegativities and valences. Dopants may be present as extra framework and unincorporated into the spinel or may be supported on the Metal-Spinel Catalyst, or especially at higher concentrations be both supported by spinel or be present in close proximity inside a physical mixture.

[0041] The RWGS catalyst is operated in the 1,300-1,800° F. range in order to achieve CO.sub.2 conversion efficiencies above 70%, which is a temperature range where many materials sinter at increased rates as they approach their melting point. The solid solution used in the catalyst should be a solid at these temperatures. Therefore, viable solid solutions are those that are formed in the 1,850-2,100° F. range. Ni.sub.2Mg and NiCu.sub.3 are stable solids at these catalyst operating temperatures, and they have excellent performance as CO.sub.2 hydrogenation catalysts. The solid solution, Cu.sub.2Mg, is formed from 2 moles of Cu and 1 mole of Mg at 1,300° F. and it doesn't qualify as a candidate since the solution is a liquid at the catalyst operating temperatures.

[0042] Type C. Engineered Layered Solids—Hydrotalcite based materials are used as catalysts for RWGS. These materials include natural hydrotalcite as well as synthetic highly engineered anionic clays or layered double hydroxides (LDH). Natural hydrotalcites may be used as additives, or as precursors for further synthesis. Synthetic Hydrotalcites are commercially available or may be prepared by coprecipitation methods.

[0043] Hydrotalcite is a layered double hydroxide (LDH)—Mg.sub.6Al.sub.2CO.sub.3(OH).sub.16.4H.sub.2O. Multiple structures containing loosely bound carbonate ions exist, which are known for their ion exchange capabilities as well as their ability to adsorb CO.sub.2. Upon calcination the material decomposes to high surface area spinel, that can easily be rehydroxylated or recarboxylated. Full thermal decomposition will lead to a spinel that is known for its hardness and durability.

[0044] LDH's are structurally derived from the brucite (Mg(OH).sub.2) structure by the isomorphous substitution of M.sup.2+ ions by M.sup.3+ ions. The LDH layers are positively charged and charge neutrality is realized by the presence of interlamellar anions. When M.sup.3+ is Al.sup.3+ the mineral hydrotalcite is obtained. The uniquely high surface area of LHD as well as their surface basicity significantly improve the performance of RWGS. The surface area, chemical composition as well as basicity of the layered solid is engineered to optimize the performance of the commercial RWGS catalyst.

[0045] Type D. Perovskite Catalysts.—Similar to the materials of Type A, perovskite materials can be used as improved RWGS catalysts. Perovskite materials have the general chemical form of ABX.sub.3. For the invention, X is Oxygen. A and B are cations. Perovskite materials can be chosen from simple perovskites such where A is chosen from the group comprising Sr, Ca, Ba, Mg, Fe, La, Ca, Pb, or Bi and B is chosen from the group comprising Al, Ti, Rb, Si, Fe, Yb or Mn. In addition, solid solution perovskite materials can also be used such as lanthanum strontium manganite, lanthanum aluminate-strontium aluminum tantalate (LSAT), lead scandium tantalate, or lead zirconate tantalate. These catalysts comprise perovskites or mixtures of various perovskites.

[0046] In the following embodiments that described the preferred catalyst compositions and catalyst performance, certain specific details provide a thorough understanding of various embodiments. Unless the context requires otherwise, throughout the specification and claims which follow, the word “comprise” and variations thereof, are to be construed in an open, inclusive sense, that is, as “including, but not limited to.”

[0047] Catalyst Composition Embodiments

[0048] 1. A reverse water gas shift (RWGS) catalyst for the conversion of H.sub.2 and CO.sub.2 mixtures into syngas comprising the process steps of: a) introducing a H.sub.2 and CO.sub.2 mixture, or b) a mixture of H.sub.2 and CO.sub.2 and light hydrocarbons, into a catalytic reactor in a catalytic conversion system to produce syngas or carbon monoxide. The product of the catalytic reactor is further reacted to produce at least one of the following products chosen from the list consisting of liquid fuels, methanol, propane, naphtha, and chemicals

[0049] 2. A reverse water gas shift (RWGS) catalyst of embodiment 1 (Type A) which comprises: a) a metal-aluminate spinel having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g, wherein the metal spinel is selected from a group consisting of: [0050] a. Group 2 metals calcined with alumina to form Mg-aluminate, Ca-aluminate, Sr-aluminate, Ba-aluminate and Be-aluminate. [0051] b. Group 1 metals calcined with alumina to form Li-aluminate, Rb-aluminate, and Cs-aluminate. [0052] c. Transition metals calcined with alumina to form Fe-aluminate, Co-aluminate, Ni-aluminate, Cu-aluminate, and Zn-aluminate. [0053] d. Rare-earth metals calcined with alumina to form La-aluminate, and Ce-aluminate. [0054] e. The above specified metal spinels may be present individually, or as mixed oxides of some or all of the above.

[0055] 3. A reverse water gas shift (RWGS) catalyst (Type B) which employs one of the metal-alumina spinels described in embodiment 2 with an impregnated metal dopant such but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce. The metal dopant may not be chemically bond to the spinel. In some embodiments only one of the above elements may be added, while in other embodiments catalyst formulations may comprise complex mixtures of several of the above elements.

[0056] Metal dopants may be introduced by impregnation, or in some cases also by physical mixing of solid precursors with the spinel. The amount of metal precursor may range from 0 to 35 wt. % of a metal salt (e.g. nitrates, acetates, carbonates, etc.) or metal hydroxides, or a metal oxide. The formed material is then calcined at a temperature up to 2,100° F., thereby synthesizing a catalyst that is a metal-impregnated, metal-alumina spinel that has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

[0057] 4. A reverse water gas shift (RWGS) catalyst of embodiment 1 (Type C), which contains an engineered layered solid in which the engineered layered solid may embody 100% of the solid catalyst without any additional additives. A reverse water gas shift (RWGS) catalyst (Type C) which employs the use of engineered layered solids with an impregnated metal dopant such but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce. The metal precursor may be a metal salt (e.g., nitrates, acetates, carbonates, etc.), or metal hydroxides, or a metal oxide. The engineered layered solid may embody 0-10% of catalyst formulation, 20-30% of catalyst formulation, 40-50% of catalyst formulation, 50-60% of catalyst formulation, 50-60% of catalyst formulation, 60-70% of catalyst formulation, 70-80% of catalyst formulation, or 80-90% of catalyst formulation. The remaining part of the formulation may be dopants or other additives needed to form a commercial catalyst. The metal dopant may not be chemically bond to the engineered layered solid. In some embodiments only one of the above elements may be added, while in other embodiments catalyst formulations may comprise complex mixtures of several of the above elements.

[0058] Metal dopants may be introduced by impregnation, or in some cases also by physical mixing of solid precursors with the engineered layered solid. The formed material is then calcined at a temperature up to 2,100° F. This reverse water gas shift (RWGS) catalyst (Type C) employs the use of natural occurring layered solid with an impregnated metal dopant such but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce. The metal precursor may be a metal salt (e.g. nitrates, acetates, carbonates, etc.), or metal hydroxides, or a metal oxide. The natural occurring layered solid may embody 0-10% of catalyst formulation, 20-30% of catalyst formulation, 40-50% of catalyst formulation, 50-60% of catalyst formulation, 50-60% of catalyst formulation, 60-70% of catalyst formulation, 70-80% of catalyst formulation, or 80-90% of catalyst formulation. The remaining part of the formulation may be dopants or other additives needed to form a commercial catalyst. The metal dopant may not be chemically bond to the engineered layered solid. In some embodiments only one of the above elements may be added, while in other embodiments catalyst formulations may comprise complex mixtures of several of the above elements. Metal dopants may be introduced by impregnation, or in some cases also by physical mixing of solid precursors with the engineered layered solid. The formed material is then calcined at a temperature up to 2,100° F.

[0059] 5. A reverse water gas shift (RWGS) catalyst of embodiment 3 wherein the catalyst is comprises the following components: a) Mg-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35 wt. % of a Mg salt; b) Mg-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; mixed with up to 35 wt. % of a CaCO.sub.3, MgCO.sub.3, SrCO.sub.3, CaO, MgO, or SrO; c) Mg-alumina spinel according to embodiment 2 having a surface area between 5 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce. d) Ca-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, and a different metal spinel of embodiment 2 of at least 10 m.sup.2/g. e) Mg-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, as well as a natural or engineered layered solid comprising 5-10% of the catalyst formulation, 20-30% of the catalyst formulation, 40-50% of the catalyst formulation, 50-60% of the catalyst formulation, 60-70% of the catalyst formulation, 70-80% of the catalyst formulation. The resulting formulation is calcined to up 2,100° F., resulting in a metal-impregnated, Mg-alumina spinel that has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

[0060] 6. A reverse water gas shift (RWGS) catalyst of embodiment 3 wherein the catalyst comprises the following components: a) Mg-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35 wt. % of a Ca salt; b) Ca-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; mixed with up to 35 wt. % of a CaCO.sub.3, MgCO.sub.3, SrCO.sub.3, CaO, MgO, or SrO; c) Ca-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce; d). Ca-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, and a different metal spinel of embodiment 2 of at least 10 m.sup.2/g; e) Ca-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, as well as a natural or engineered layered solid comprising 5-10% of the catalyst formulation, 20-30% of the catalyst formulation, 40-50% of the catalyst formulation, 50-60% of the catalyst formulation, 60-70% of the catalyst formulation, 70-80% of the catalyst formulation. The resulting formulation is calcined to up 2,100° F., resulting in a metal-impregnated, Ca-alumina spinel that has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

[0061] 7. A reverse water gas shift (RWGS) catalyst of embodiment 3 wherein the catalyst is comprises the following components: a) Mg-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35 wt. % of a Sr salt; b) Sr-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; mixed with up to 35 wt. % of a CaCO.sub.3, MgCO.sub.3, SrCO.sub.3, CaO, MgO, or SrO; c) Sr-alumina spinel according to embodiment 2 having a surface area between 10 m2/g and 1000 m2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce; d) Sr-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, and a different metal spinel of embodiment 2 of at least 10 m.sup.2/g; e) Sr-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, as well as a natural or engineered layered solid comprising 5-10% of the catalyst formulation, 20-30% of the catalyst formulation, 40-50% of the catalyst formulation, 50-60% of the catalyst formulation, 60-70% of the catalyst formulation, 70-80% of the catalyst formulation. The resulting formulation is calcined to up 2,100° F., resulting in a metal-impregnated, Sr-alumina spinel that has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

[0062] 8. A reverse water gas shift (RWGS) catalyst of embodiment 3 wherein the catalyst is comprises the following components: a) Mg-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35 wt. % of a Ba salt; b) Ba-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; mixed with up to 35 wt. % of CaCO.sub.3, MgCO.sub.3, SrCO.sub.3, CaO, MgO, or SrO; c) Ba-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce; d) Ba-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, and a different metal spinel of embodiment 2 of at least 10 m.sup.2/g; e) Ba-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, as well as a natural or engineered layered solid comprising 5-10% of the catalyst formulation, 20-30% of the catalyst formulation, 40-50% of the catalyst formulation, 50-60% of the catalyst formulation, 60-70% of the catalyst formulation, 70-80% of the catalyst formulation. The resulting formulation is calcined to up 2,100° F., resulting in a metal-impregnated, Ba-alumina spinel that has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

[0063] 9. A reverse water gas shift (RWGS) catalyst of embodiment 3 wherein the catalyst comprises the following components: a) Mg-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35 wt. % of a Li salt; b) Li-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; mixed with up to 35 wt. % of CaCO.sub.3, MgCO.sub.3, SrCO.sub.3, CaO, MgO, or SrO; c) Li-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce; d) Li-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000.Math.m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, and a different metal spinel of embodiment 2 of at least 10 m.sup.2/g; e) Li-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, as well as a natural or engineered layered solid comprising 5-10% of the catalyst formulation, 20-30% of the catalyst formulation, 40-50% of the catalyst formulation, 50-60% of the catalyst formulation, 60-70% of the catalyst formulation, 70-80% of the catalyst formulation. The resulting formulation is calcined to up 2,100° F., resulting in a metal-impregnated, Li-alumina spinel that has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

[0064] 10. A reverse water gas shift (RWGS) catalyst of embodiment 3 wherein the catalyst is comprises the following components: a) Mg-alumina spinel according to embodiment 2 having a surface area between 10 m2/g and 1000 m2/g; impregnated with up to 35 wt. % of a Rb salt; b) Rb-alumina spinel according to embodiment 2 having a surface area between 10 m2/g and 1000 m2/g; mixed with up to 35 wt. % of CaCO.sub.3, MgCO.sub.3, SrCO.sub.3, CaO, MgO, or SrO; c) Rb-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce; d) Rb-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, and a different metal spinel of embodiment 2 of at least 10 m.sup.2/g; e) Rb-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, as well as a natural or engineered layered solid comprising 5-10% of the catalyst formulation, 20-30% of the catalyst formulation, 40-50% of the catalyst formulation, 50-60% of the catalyst formulation, 60-70% of the catalyst formulation, 70-80% of the catalyst formulation. The resulting formulation is calcined to up 2,100° F., resulting in a metal-impregnated, Rb-alumina spinel that has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

[0065] 11. A reverse water gas shift (RWGS) catalyst of embodiment 3 wherein the catalyst is comprises the following components: a) Mg-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35 wt. % of a Cs salt; b) Cs-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; mixed with up to 35 wt. % of CaCO.sub.3, MgCO.sub.3, SrCO.sub.3, CaO, MgO, or SrO; c) Ni-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce; d) Cs-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, and a different metal spinel of embodiment 2 of at least 10 m.sup.2/g; e) Cs-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, as well as a natural or engineered layered solid comprising 5-10% of the catalyst formulation, 20-30% of the catalyst formulation, 40-50% of the catalyst formulation, 50-60% of the catalyst formulation, 60-70% of the catalyst formulation, 70-80% of the catalyst formulation. The resulting formulation is calcined to up 2,100° F., resulting in a metal-impregnated, Cs-alumina spinel that has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

[0066] 12. A reverse water gas shift (RWGS) catalyst of embodiment 3 wherein the catalyst is comprises the following components: a) Mg-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35 wt. % of a Fe salt; b) Fe-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; mixed with up to 35 wt. % of CaCO.sub.3, MgCO.sub.3, SrCO.sub.3, CaO, MgO, or SrO; c) Fe-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce; d) Fe-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, and a different metal spinel of embodiment 2 of at least 10 m.sup.2/g; e) Fe-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, as well as a natural or engineered layered solid comprising 5-10% of the catalyst formulation, 20-30% of the catalyst formulation, 40-50% of the catalyst formulation, 50-60% of the catalyst formulation, 60-70% of the catalyst formulation, 70-80% of the catalyst formulation. The resulting formulation is calcined to up 2,100° F., resulting in a metal-impregnated, Fe-alumina spinel that has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

[0067] 13. A reverse water gas shift (RWGS) catalyst of embodiment 3 wherein the catalyst is comprises the following components: a) Mg-alumina spinel according to embodiment 2 having a surface area between 10 m2/g and 1000 m2/g; impregnated with up to 35 wt. % of a Co salt; b) Ni-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; mixed with up to 35 wt. % of CaCO.sub.3, MgCO.sub.3, SrCO.sub.3, CaO, MgO, or SrO; c) Ni-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce; d) Co-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, and a different metal spinel of embodiment 2 of at least 10 m.sup.2/g; e) Co-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, as well as a natural or engineered layered solid comprising 5-10% of the catalyst formulation, 20-30% of the catalyst formulation, 40-50% of the catalyst formulation, 50-60% of the catalyst formulation, 60-70% of the catalyst formulation, 70-80% of the catalyst formulation. The resulting formulation is calcined to up 2,100° F., resulting in a metal-impregnated, Co-alumina spinel that has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

[0068] 14. A reverse water gas shift (RWGS) catalyst of embodiment 3 wherein the catalyst is comprises the following components: a) Mg-alumina spinel according to embodiment 2 having a surface area between 10 m2/g and 1000 m2/g; impregnated with up to 35 wt. % of a Ni salt; b) Ni-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m2/g; mixed with up to 35 wt. % of CaCO.sub.3, MgCO.sub.3, SrCO.sub.3, CaO, MgO, or SrO; c) Ni-alumina spinel according to embodiment 2 having a surface area between 10 m2/g and 1000 m2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce; d) Ni-alumina spinel according to embodiment 2 having a surface area between 10 m2/g and 1000 m2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, and a different metal spinel of embodiment 2 of at least 10 m.sup.2/g; e) Ni-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, as well as a natural or engineered layered solid comprising 5-10% of the catalyst formulation, 20-30% of the catalyst formulation, 40-50% of the catalyst formulation, 50-60% of the catalyst formulation, 60-70% of the catalyst formulation, 70-80% of the catalyst formulation. The resulting formulation is calcined to up 2,100° F., resulting in a metal-impregnated, Ni-alumina spinel that has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

[0069] 15. A reverse water gas shift (RWGS) catalyst of embodiment 3 wherein the catalyst is comprises the following components: a) Mg-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35 wt. % of a Cu salt; b) Cu-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; mixed with up to 35 wt. % of CaCO.sub.3, MgCO.sub.3, SrCO.sub.3, CaO, MgO, or SrO; c) a Cu-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce; d) Cu-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, as a different metal spinel of at least 10 m.sup.2/g; e) Cu-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, as well as a natural or engineered layered solid comprising 5-10% of the catalyst formulation, 20-30% of the catalyst formulation, 40-50% of the catalyst formulation, 50-60% of the catalyst formulation, 60-70% of the catalyst formulation, 70-80% of the catalyst formulation. The resulting formulation is calcined to up 2,100° F., resulting in a metal-impregnated, Cu-alumina spinel that has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

[0070] 16. A reverse water gas shift (RWGS) catalyst of embodiment 3 wherein the catalyst is comprises the following components: a) Mg-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35 wt. % of a Zn salt; b) Zn-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; mixed with up to 35 wt. % of CaCO.sub.3, MgCO.sub.3, SrCO.sub.3, CaO, MgO, or SrO; c) Zn-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce; d) Zn-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, as a different metal spinel of at least 10 m.sup.2/g; e) Zn-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, as well as a natural or engineered layered solid comprising 5-10% of the catalyst formulation, 20-30% of the catalyst formulation, 40-50% of the catalyst formulation, 50-60% of the catalyst formulation, 60-70% of the catalyst formulation, 70-80% of the catalyst formulation. The resulting formulation is calcined to up 2,100° F., resulting in a metal-impregnated, Zn-alumina spinel that has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

[0071] 17. A reverse water gas shift (RWGS) catalyst of embodiment 3 wherein the catalyst is comprises the following components: a) Mg-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35 wt. % of a La salt; b) La-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; mixed with up to 35 wt. % of CaCO.sub.3, MgCO.sub.3, SrCO.sub.3, CaO, MgO, or SrO; c) La-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce; d) La-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, as a different metal spinel of at least 10 m.sup.2/g; e) a La-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, as well as a natural or engineered layered solid comprising 5-10% of the catalyst formulation, 20-30% of the catalyst formulation, 40-50% of the catalyst formulation, 50-60% of the catalyst formulation, 60-70% of the catalyst formulation, 70-80% of the catalyst formulation. The resulting formulation is calcined to up 2,100° F., resulting in a metal-impregnated, La-alumina spinel that has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

[0072] 18. A reverse water gas shift (RWGS) catalyst of embodiment 3 wherein the catalyst is comprises the following components: a) Mg-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35 wt. % of a Ce salt; b) Ce-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; mixed with up to 35 wt. % of CaCO.sub.3, MgCO.sub.3, SrCO.sub.3, CaO, MgO, or SrO; c) Ce-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce; d) Ce-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, as a different metal spinel of at least 10 m.sup.2/g; e) a Zn-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; impregnated with up to 35% of mixtures of primary, secondary, ternary, or more mixtures of salt mixtures including but not limited to Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, as well as a natural or engineered layered solid comprising 5-10% of the catalyst formulation, 20-30% of the catalyst formulation, 40-50% of the catalyst formulation, 50-60% of the catalyst formulation, 60-70% of the catalyst formulation, 70-80% of the catalyst formulation. The resulting formulation is calcined to up 2,100° F., resulting in a metal-impregnated, Ce-alumina spinel that has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

[0073] 19. Although the embodiments 5-18 cover the formulations of a CO.sub.2 hydrogenation catalyst that focuses on the impregnation of a specific metal on a metal-alumina spinel synthesized from the same metal, the various permutations of the other metals in embodiment 3 on the other metal-spinels in embodiment 2 are covered (e.g., Ni on Mg-aluminate; Ni on Ba-aluminate, etc.).

[0074] 20. This embodiment comprises a reverse water gas shift (RWGS) catalyst (Type C) which employs one of the metal-alumina spinels described in embodiment 2 with a) the impregnation of up to 35 wt. % of two metal salts (e.g. nitrates, acetates, carbonates, etc.) or metal hydroxides selected from a group comprising Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, which don't chemically bond to the spinel; b) calcining the metal-alumina spinel impregnated with the two or more metals at a temperature up to 2,100° F., thereby synthesizing a solid-solution of the two metals on the metal-alumina spinel.

[0075] 21. The reverse water gas shift (RWGS) catalyst of embodiment 20 wherein the catalyst is produced by a process comprising the steps of: a) synthesizing a Mg-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; b) impregnating the spinel with up to 35 wt. % of a mixture of Ni and Mg; c) calcining the Ni- and Mg-impregnated, Mg-alumina spinel at a temperature up to 2,100° F.; d) thereby producing a solid-solution of the two metals that has the composition Ni.sub.2Mg. Ni and Mg form a solid solution at 2,100° F. since Ni and Mg both crystallize in a face-centered cubic structure, have similar electronegativities and valences.

[0076] 22. The reverse water gas shift (RWGS) catalyst of embodiment 20 wherein the catalyst is produced by a process comprising the steps of: a) synthesizing a Mg-alumina spinel according to embodiment 2 having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; b) impregnating the spinel with up to 35 wt. % of a mixture of Ni and Cu; c) calcining the Ni- and Mg-impregnated, Mg-alumina spinel at a temperature up to 2,100° F.; d) thereby producing a solid-solution of the two metals that has the composition NiCu.sub.3. Ni and Cu form a solid solution at 2,100° F. since Ni and Cu both crystallize in a face-centered cubic structure, have similar atomic radii, electronegativities and valences.

Catalyst Performance Embodiments

[0077] Most of the improved CO.sub.2 hydrogenation catalysts described above in the Catalyst Composition Embodiments meet the commercial quality and performance specifications summarized in Table 1.

[0078] 1. Low-Cost Constituents—The catalysts are formulated primarily using low-cost Group 1 elements (Alkali Metals) comprising Na, K, Li, Cs and Rb; the Group 2 elements (Alkaline Earth Metals): Mg, Ca, Sr, Ba and Be; the Transition Metals comprising Ni, Co, Fe and Cu; and the Rare-Earth elements comprising Ce, Y, La. It has been found that the addition of small quantities of precious metals (such as Au, Ag, Pt, Pd, Ir) do not improve the performance of these improved CO.sub.2 hydrogenation catalysts.

[0079] 2. Commercial Production—The substrates and catalysts are economically produced in multiple ton quantities using well established commercial-scale production processes. The metal alumina spinel substrates may be prepared by a) coprecipitation methods or b) by mixing appropriate molar quantities of a metal precursors and alumina particles to form a slurry, drying the slurry, and then calcining the mixture up to 2,600° F. The catalysts are prepared by the impregnation of the metal(s) on the metal-alumina spinel substrates followed by calcination up to 2,100° F.

[0080] 3. Physically Robust—The disclosed catalysts have hardness of between 4 Mohs and 10 Mohs, or an equivalent Rockwell hardness. This high level of hardness eliminates the potential problem of catalyst breakage, cracking and ablation.

[0081] 4. Chemically and Physically Stable—These a). metal-alumina spinels, b). metal impregnated metal metal-alumina spinels and c). solid solutions impregnated on the metal metal-alumina spinels maintain their chemical and physical properties (such as not melt) up to 2,100° F.

[0082] 5. Compatible with Commercial Catalytic Reactors—The catalyst pellets, tablets, or hollow tablets are easy to load into catalytic reactors (tubular, or packed bed reactors). The pressure drop from the top to the bottom of the catalytic reactors is between 0 and 50 psi and usually between 0 and 25 psi. The activation of the catalyst (e.g., reduction with H.sub.2) is carried out in-situ if required.

[0083] 6. High CO.sub.2 Conversion Efficiency—The CO.sub.2 to CO conversion efficiency for H.sub.2/CO.sub.2 blends with ratios higher than 3.0/1.0 is between 70% and 100%, preferably between 75% and 100%, and more preferably between 80% and 100% at space velocities between 2,000 hr.sup.−1 and 1,000,000 hr.sup.−1 and temperatures between 1,300° F. and 1,800° F.

[0084] 7. High CO Production Selectivity—The disclosed catalyst formulations have CO of at least 90%. Some of the preferred catalyst formulations have CO selectivities greater than 99% with methane selectivities below 1%, and CO selectivities as low as 0.1% in some cases.

[0085] 8. Doesn't Coke or Change Composition—These improved catalyst formulations do not coke or change chemical composition during operation.

[0086] 9. Long-Term Performance—Several of the improved CO.sub.2 hydrogenation catalysts have been tested for more than 1,500 hrs. on stream and it has been determined that the reduction in CO.sub.2 conversion is between 0 and 0.50% per 1000 hours.

Examples

[0087] Example 1: Improved RWGS Catalyst Formulation A—A stream comprising CO.sub.2 is produced by an industrial process or captured from ambient air. This CO.sub.2 stream is fed to a CO.sub.2 capture facility. The CO.sub.2 capture facility uses methyl diethanolamine (MDEA) in an absorber tower to capture the CO.sub.2. Relatively pure CO.sub.2 is regenerated from the MDEA by heating. Low-carbon electricity from a wind farm, a solar farm, a nuclear power plant, or other low-carbon power sources is available at the site of the carbon capture facility. High-purity water is produced from locally available water. Low-carbon H.sub.2 is produced from the purified water via electrolysis.

[0088] This reaction uses the low-carbon electricity to split the water into H.sub.2 and O.sub.2. The electrolyzer in this example is a PEM Electrolyzer. The electrolyzer produces two streams, H.sub.2 and O.sub.2.

[0089] This improved catalyst formulation A of embodiment 2 (above) is manufactured by a method comprising the steps of: a) synthesizing a metal-aluminate spinel having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g, wherein the metal spinel is selected from a group comprising: [0090] a. Group 2 metals calcined with alumina to form Mg-aluminate, Ca-aluminate, Sr-aluminate, Ba-aluminate and Be-aluminate. [0091] b. Group 1 metals calcined with alumina to form Li-aluminate, Rb-aluminate, and Cs-aluminate. [0092] c. Transition metals calcined with alumina to form Fe-aluminate, Co-aluminate, Ni-aluminate, Cu-aluminate, and Zn-aluminate. [0093] d. Rare-earth metals calcined with alumina to form La-aluminate, and Ce-aluminate.

[0094] The improved catalyst is used to convert the captured CO.sub.2 and renewable H.sub.2 stream into syngas. Example 1 provides the relationship between temperature and % CO.sub.2 conversion to CO for the improved CO.sub.2 hydrogenation catalyst. In this example, the H.sub.2 to CO.sub.2 ratio is 3.4/1.0, the pressure is 300 psig, and the space velocity is 20,000 hr.sup.−1. The conversion of CO.sub.2 varies from 75% to 83.5% from 1,250-1,650° F. with between 0 and 0.5% conversion reduction after 1,000 hrs. on stream. Since the catalysts at these relevant temperature ranges exhibits very little sintering, their lifetime is excellent. The CO selectivity is >99.5% with between 0 and 0.5% CH.sub.4 selectivity. The dotted line is the trendline which shows that the relationship between CO.sub.2 conversion and temperature is nearly linear.

Example 1—The Typical Relationship between Temperature and % CO.sub.2 Conversion to CO for the Improved RWGS Catalysts. FIG. 1 shows the typical relationship between Temperature and % CO.sub.2 Conversion to 0 for the Improved RWGS Catalysts. The X-Axis is temperature in degrees Fahrenheit. The Y-Axis is the CO.sub.2 Conversion in mole percent to CO. As can be seen at a temperature of 1200° F. to 1750° F., the CO.sub.2 conversion is between 70 and 85%.

[0095] Example 2: Improved RWGS Catalyst Formulation B—This improved catalyst formulation B is described in embodiment #3 (above) as a metal on a metal aluminate. This type B CO.sub.2 hydrogenation catalyst employs one of the metal-alumina spinels described in embodiment 2 with a) the impregnation of up to 35 wt. % of a metal salt (e.g. nitrates, acetates, carbonates, etc.) or metal hydroxide selected from a group comprising Mg, Ca, Sr, Ba, Li, Rb, Cs, Fe, Co, Ni, Cu, Zn, La and Ce, which don't chemically bond to the spinel; b) calcining the impregnated, metal-coated metal-alumina spinel at a temperature up to 2,100° F., thereby synthesizing a catalyst that is an metal-impregnated, metal-alumina spinel that has a surface area between 5 m.sup.2/g and 1000 m.sup.2/g.

[0096] In this example the catalyst is MgO or Mg(OH).sub.2 impregnated on a Mg-Alumina Spinel. The MgO or Mg(OH).sub.2 is reduced in-situ with H.sub.2, producing Mg, MgO and Mg(OH).sub.2 on the surface of the spinel.

[0097] The improved catalyst is used to convert the captured CO.sub.2 and renewable H.sub.2 stream into syngas. In this example, the H.sub.2 to CO.sub.2 ratio is 3.4/1.0, the temperature is 1,650° F., the pressure is 300 psig, and the space velocity is 20,000 h.sup.−1. The conversion of CO.sub.2 is 82% at 1,650° F. with between 0 and 0.5% conversion reduction after 1,000 hrs. on stream. The CO selectivity is greater than 99%.

[0098] Example 3: Improved RWGS Catalyst Formulation C—This improved RWGS catalyst C is described in embodiments 20-23 for the efficient conversion of CO.sub.2 and H.sub.2 into syngas by a process comprising the steps of: a) synthesizing a Mg-aluminate spinel having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; b) coating the spinel with up to 20 wt. % of Mg to provide a metal-coated spinel; c) impregnating the metal-coated spinel with a solution comprising water soluble nickel salts and either nitrate or acetate salts of rare-earth metals; d) calcining the impregnated, metal-coated spinet at a temperature up to 2,100° F., thereby synthesizing a catalyst that is an impregnated spinel that is comprised with up to 35 wt. % nickel and of 0.1 wt. % to 5.0 wt. % of the rare earth metals. The catalyst may contain 0.1 to 5 parts-by-weight of cerium, ruthenium, lanthanum, platinum, or rhenium, and 2 wt. % to 20 wt. % nickel per 100 parts-by-weight of the spinel support. As described in embodiment #21, the solid solution catalyst is Ni.sub.2Mg.

[0099] Another improved catalyst type C for the efficient conversion of CO.sub.2 and H.sub.2 into syngas is produced by a process comprising the steps of a) synthesizing a Cu impregnated Cu-aluminate spinel having a surface area between 10 m.sup.2/g and 1000 m.sup.2/g; b) coating the spinel with up to 20 wt. % of Cu to provide a metal-coated spinel; c) impregnating the metal-coated spinel with a solution comprising water soluble Ni salts and either nitrate or acetate salts of rare-earth metals; d) calcining the impregnated, metal-coated spinel at a temperature up to 2,100° F., thereby synthesizing a catalyst that is an impregnated spinel that is comprised with up to 20 wt. % nickel and of 0.1 wt. % to 5.0 wt. % of the rare earth metals. As described in embodiment #22, the primary solid solution catalysts are NiCu.sub.3.

[0100] The relationship between temperature and CO.sub.2 conversion efficiency (Example #1) is similar for catalyst #1 and catalyst #2. The difference is that catalyst #1 has between 0 and 0.5% CH.sub.4 selectivity compared to up to 7.0% CH.sub.4 selectivity (depending upon temperature and pressure) for catalyst #2. However, catalyst #2 is more efficient at higher space velocities.

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