WO2024000343A1

WO2024000343A1 - Nickel catalysts for reverse water-gas shift processes

Info

Publication number: WO2024000343A1
Application number: PCT/CN2022/102630
Authority: WO
Inventors: Gareth ARMITAGE; John Glenn Sunley; Meiling GUO; Christiana UDOH; Eric Doskocil; James Paterson; Ben DENNIS-SMITHER; Xuebin Liu
Original assignee: Bp P.L.C.; Bp (China) Holdings Limited
Priority date: 2022-06-30
Filing date: 2022-06-30
Publication date: 2024-01-04

Abstract

A supported reverse water-gas shift catalyst comprising: a support that is a cerium oxide support, a titanium oxide support, an aluminum oxide support, a zirconium oxide support, or a mixed oxide support comprising a mixture of two or more of cerium oxide, titanium oxide, aluminum oxide, and zirconium oxide; nickel, present in an amount in the range of 0.05 to 10 wt% of the catalyst, based on the total weight of the catalyst; and manganese, present in an amount in the range of 0.5 to 20 wt% of the catalyst, based on the total weight of the catalyst.

Description

NICKEL CATALYSTS FOR REVERSE WATER-GAS SHIFT PROCESSES

1. Field

The present disclosure relates generally to reverse water-gas shift catalysts, methods of making the same, and methods for performing reverse water-gas shift reactions.

2. Technical background

The reverse water-gas shift reaction (rWGS) is an advantageous route to obtain carbon monoxide from carbon dioxide for further chemical processing. The rWGS converts carbon dioxide and hydrogen to carbon monoxide and water, as shown in Equation (1) .

This can be used, for example, to modify the CO: H ₂ ratio of a gas mixture for further processing. The carbon monoxide and hydrogen so formed is a valuable feedstock for a number of chemical processes, for example, the well-known Fischer-Tropsch process, shown in Equation (2) .

However, the rWGS reaction is not favored in all circumstances. For example, acompeting reaction is the Sabatier reaction (Equation (3) ) , which decreases carbon monoxide yield in favor of methane production.

The strongly exothermic Sabatier reaction is thermodynamically favored over the endothermic rWGS reaction at lower reaction temperatures. As such, minimizing the methanation during rWGS, especially at low temperatures, can become a significant challenge.

Similarly, the carbon monoxide product from rWGS can be hydrogenated to methane, as shown in Equation (4) .

Hydrogenation of carbon monoxide to methane is also an exothermic reaction, so it too is favored at lower temperatures. The stoichiometry of the reaction requires at least a 3: 1 ratio of hydrogen to carbon monoxide. This means that performing the rWGS reaction with a large excess of hydrogen to drive the equilibrium toward carbon monoxide (see Equation (1) ) is not always ideal because it runs the risk of hydrogenating the carbon monoxide product to form methane.

Coupled with equations (3) and (4) , further undesirable side reactions can occur. These side reactions can form undesirable carbon deposits on the surface of catalysts used to promote rWGS. Examples of these carbon-producing side reactions are shown in Equations (5) , (6) , and (7) . All three of these reactions are endothermic and are favored at higher temperatures, just like the rWGS reaction.

Accordingly, because the carbon-producing side reactions (Equations (5) - (7) ) are also endothermic and are favored at higher temperatures, operation at higher temperatures to favor the desired carbon monoxide product can severely impact catalyst lifetime through the deposition of carbon.

Given the multiple reactions and competing thermodynamics at play, there remains a need in the art for new rWGS catalysts and processes.

SUMMARY

In one aspect, the present disclosure provides for a supported reverse water-gas shift catalyst comprising:

a support that is a cerium oxide support, a titanium oxide support, an aluminum oxide support, a zirconium oxide support, or a mixed oxide support comprising a mixture of two or more of cerium oxide, titanium oxide, aluminum oxide, and zirconium oxide;

nickel, present in an amount in the range of 0.05 to 10 wt%of the catalyst, based on the total weight of the catalyst; and

manganese, present in an amount in the range of 0.5 to 20 wt%of the catalyst, based on the total weight of the catalyst.

In another aspect, the present disclosure provides for a method of making the catalyst as described herein, the method comprising:

providing a support that is a cerium oxide support, a titanium oxide support, an aluminum oxide support, a zirconium oxide support, or a mixed oxide support comprising a mixture of two or more of cerium oxide, titanium oxide, aluminum oxide, and zirconium oxide;

contacting the support with a liquid comprising one or more nickel-containing compounds and one or more manganese-containing compounds dispersed in a solvent;

allowing the solvent to evaporate to provide a catalyst precursor; and

calcining the catalyst precursor.

In another aspect, the present disclosure provides for a catalyst as described herein made by the method as described herein.

In another aspect, the present disclosure provides a method for performing a reverse water-gas shift reaction, the method comprising contacting at a temperature in the range of 500-900℃ a catalyst as described herein with a feed stream comprising CO ₂ and H ₂, to provide a product stream comprising CO and H ₂, the product stream having a lower concentration of CO ₂ and a higher concentration of CO than the feed stream.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 is a schematic of the reverse water-gas shift reaction as described herein.

DETAILED DESCRIPTION

As discussed above, the reverse gas-water shift reaction reacts carbon dioxide with hydrogen to form carbon monoxide and water, and can be useful in providing a feedstock containing carbon monoxide and hydrogen--often called “synthesis gas” --for use in processes such as the Fischer-Tropsch process. However, the Sabatier reaction, carbon monoxide methanation, and carbon-producing side reactions can interfere with the rWGS reaction. The Sabatier reaction and CO methanation are exothermic and favored at lower temperatures, while the rWGS and carbon-producing side reactions are endothermic and favored at higher temperatures. Accordingly, there remains a need for rWGS catalysts that can provide good performance in spite of these complicating factors. Here, the present inventors have provided supported reverse water-gas shift catalysts that include a metal oxide support, nickel and manganese, that can meet the requirements necessary for a commercially-useful rWGS process.

In one aspect, the present disclosure provides a supported reverse water-gas shift catalyst including a support that is a cerium oxide support, a titanium oxide support, an aluminum oxide support, a zirconium oxide support, or a mixed oxide support including a mixture of two or more of cerium oxide, titanium oxide, aluminum oxide, and zirconium oxide; at least one of nickel, present in an amount in the range of 0.05 to 10 wt%of the catalyst, based on the total weight of the catalyst; and manganese, present in an amount in the range of 0.5 to 20 wt%of the catalyst, based on the total weight of the catalyst.

As described above, the reverse water-gas shift catalysts of the present disclosure are supported catalysts. In various embodiments as otherwise described herein, the support makes up at least 70 wt%, e.g., at least 75 wt%, or 80 wt%, or 85 wt%, or 90 wt%of the catalyst on an oxide basis.

In various embodiments as otherwise described herein, the support is a cerium oxide support. As used herein, a "cerium oxide” support is a support that presents at least a surface layer (e.g., 50 microns in thickness) that is at least 50 wt%cerium oxide, on an oxide basis. In various embodiments of the disclosure as described herein, at least a surface layer of the cerium oxide support includes at least 60 wt%cerium oxide, e.g., at least 70 wt%cerium oxide, or at least 80 wt%cerium oxide. In some such embodiments, at least a surface layer of the cerium oxide support includes at least 90 wt%cerium oxide. For example, in some embodiments, at least a surface layer of the cerium oxide support includes at least 95 wt%cerium oxide or at least 98 wt%cerium oxide. In various examples, the cerium oxide support contains cerium oxide substantially throughout, e.g., at least 50 wt%of the cerium oxide support is cerium oxide on an oxide basis. For example, in various embodiments, the cerium oxide support includes at least 60 wt%cerium oxide, e.g., at least 70 wt%cerium oxide, or at least 80 wt%cerium oxide. In various embodiments, the cerium oxide support includes at least 90 wt%cerium oxide, e.g., at least 95 wt%cerium oxide, or at least 98 wt%cerium oxide. In some embodiments, the cerium oxide support may further include additional metals or metal oxides.

In various embodiments as otherwise described herein, the support is a titanium oxide support. As used herein, a "titanium oxide” support is a support that presents at least a surface layer (e.g., 50 microns in thickness) that is at least 50 wt%titanium oxide, on an oxide basis. In various embodiments of the disclosure as described herein, at least a surface layer of the titanium oxide support includes at least 60 wt%titanium oxide, e.g., at least 70 wt%titanium oxide, or at least 80 wt%titanium oxide. In some such embodiments, at least a surface layer of the titanium oxide support includes at least 90 wt%titanium oxide. For example, in some embodiments, at least a surface layer of the titanium oxide support includes at least 95 wt%titanium oxide or at least 98 wt%titanium oxide. In various examples, the titanium oxide support contains titanium oxide substantially throughout, e.g., at least 50 wt%of the titanium oxide support is titanium oxide on an oxide basis. For example, in various embodiments, the titanium oxide support includes at least 60 wt%titanium oxide, e.g., at least 70 wt%titanium oxide, or at least 80 wt%titanium oxide. In various embodiments, the titanium oxide support includes at least 90 wt%titanium oxide, e.g., at least 95 wt%titanium oxide, or at least 98 wt%titanium oxide. In some embodiments, the titanium oxide support may further include additional metals or metal oxides.

In various embodiments as otherwise described herein, the support is an aluminum oxide support. As used herein, an "aluminum oxide” support is a support that presents at least a surface layer (e.g., 50 microns in thickness) that is at least 50 wt% aluminum oxide, on an oxide basis. In various embodiments of the disclosure as described herein, at least a surface layer of the aluminum oxide support includes at least 60 wt%aluminum oxide, e.g., at least 70 wt%aluminum oxide, or at least 80 wt%aluminum oxide. In some such embodiments, at least a surface layer of the aluminum oxide support includes at least 90 wt%aluminum oxide. For example, in some embodiments, at least a surface layer of the aluminum oxide support includes at least 95 wt%aluminum oxide or at least 98 wt%aluminum oxide. In various examples, the aluminum oxide support contains aluminum oxide substantially throughout, e.g., at least 50 wt%of the aluminum oxide support is aluminum oxide on an oxide basis. For example, in various embodiments, the aluminum oxide support includes at least 60 wt%aluminum oxide, e.g., at least 70 wt%aluminum oxide, or at least 80 wt%aluminum oxide. In various embodiments, the aluminum oxide support includes at least 90 wt%aluminum oxide, e.g., at least 95 wt%aluminum oxide, or at least 98 wt%aluminum oxide. In some embodiments, the aluminum oxide support may further include additional metals or metal oxides.

In various embodiments as otherwise described herein, the support is a zirconium oxide support. As used herein, a "zirconium oxide” support is a support that presents at least a surface layer (e.g., 50 microns in thickness) that is at least 50 wt%zirconium oxide, on an oxide basis. In various embodiments of the disclosure as described herein, at least a surface layer of the zirconium oxide support includes at least 60 wt%zirconium oxide, e.g., at least 70 wt%zirconium oxide, or at least 80 wt%zirconium oxide. In some such embodiments, at least a surface layer of the zirconium oxide support includes at least 90 wt%zirconium oxide. For example, in some embodiments, at least a surface layer of the zirconium oxide support includes at least 95 wt%zirconium oxide or at least 98 wt%zirconium oxide. In various examples, the zirconium oxide support contains zirconium oxide substantially throughout, e.g., at least 50 wt%of the zirconium oxide support is zirconium oxide on an oxide basis. For example, in various embodiments, the zirconium oxide support includes at least 60 wt%zirconium oxide, e.g., at least 70 wt%zirconium oxide, or at least 80 wt%zirconium oxide. In various embodiments, the zirconium oxide support includes at least 90 wt%zirconium oxide, e.g., at least 95 wt%zirconium oxide, or at least 98 wt%zirconium oxide. In some embodiments, the zirconium oxide support may further include additional metals or metal oxides.

In various embodiments as otherwise described herein, the support is a mixed oxide support. These can be provided, for example, by admixture of multiple of the oxides above and formation into a support that includes both. For example, in some embodiments, the mixed oxide support is a mixture of two or more metal oxides, such as cerium oxide, titanium oxide, aluminum oxide, and zirconium oxide. In some embodiments, at least a surface layer of the support includes at least 50 wt%total of two or more of cerium oxide, titanium oxide, aluminum oxide, and zirconium oxide, on an oxide basis. In some embodiments, at least a surface layer of the mixed oxide support includes at least 60 wt%total, e.g., at least 70 wt%, or at least 80 wt%of two or more of cerium oxide, titanium oxide, aluminum oxide, and zirconium oxide. In some embodiments, at least a surface layer of the mixed oxide support includes at least 90 wt%, e.g., at least 95 wt%, or at least 98 wt%of two or more cerium oxide, titanium oxide, aluminum oxide, and zirconium oxide. In various examples, the mixed oxide support contains the oxides substantially throughout, e.g., at least 50 wt%of the mixed oxide support is two or more of cerium oxide, titanium oxide, aluminum oxide, and zirconium oxide. In various embodiments, the mixed oxide support includes at least 60 wt%total, e.g., at least 70 wt%, or at least 80 wt%of two or more of cerium oxide, titanium oxide, aluminum oxide, and zirconium oxide. In various embodiments, the mixed oxide support includes at least 90 wt%total, e.g., at least 95 wt%, or at least 98 wt%of two or more of cerium oxide, titanium oxide, aluminum oxide, and zirconium oxide. In some embodiments, the mixed oxide support may further include additional metals or metal oxides.

The present inventors have found that cerium oxide, titanium oxide, aluminum oxide, and zirconium oxide can provide good performance in the absence of substantial amounts of other metals in the support. For example, in various embodiments of the disclosure as otherwise described herein, the support does not include additional metals in a total amount of additional metals in excess of 2 wt%, e.g., in excess of 1 wt%or in excess of 0.5 wt%, on an oxide basis.

However, the inventors have noted that in many cases performance can be desirably effected by the inclusion of other metals in the support. Accordingly, in other embodiments as otherwise described herein, the support includes at least one additional metal. In various embodiments, the total amount of the at least one additional metal is in the range of 0.5-20 wt%, e.g., 1-20 wt%, or 2-20 wt%, or 0.5-15 wt%, or 1-15 wt%, or 2-15 wt%, or 0.5-10 wt%, or 1-10 wt%, or 2-10 wt%, or 0.5-5 wt%, or 1-5 wt%, on an oxide basis.

Supports suitable for use herein can be provided with a range of pore volumes. The person of ordinary skill in the art will select a pore volume appropriate for a desired catalytic process. For example, in various embodiments as otherwise described herein, the pore volume is at least 0.05 mL/g, e.g., at least 0.1 mL/g. In various embodiments as otherwise described herein, the pore volume is at most 1.5 mL/g, e.g., at most 1 mL/g. In various embodiments of the present disclosure as described herein, the pore volume is in the range of 0.05-1.5 mL/g, e.g., 0.1 mL/g to 1 mL/g. Pore volumes are measured by mercury porosimetry, for example, as measured according to ASTM D4284-12.

As described above, the supported reverse water-gas shift catalysts of the disclosure includes nickel. For example, in various embodiments as otherwise described herein, nickel is present in the catalyst. For the purposes of this disclosure, the amount of nickel present is calculated as a weight percentage of nickel atoms in the catalyst based on the total weight of the catalyst, despite the form in which that nickel may be present. The nickel may be present in the catalyst in a variety of forms; most commonly, nickel is principally present as metal, metal oxide, or a combination thereof. In some embodiments of the present disclosure as described herein, nickel is present in the catalyst in an amount in the range of 0.05 to 10 wt%, e.g., in the range of 0.1 to 10 wt%, or 0.5 to 10 wt%, 1 to 10 wt%, or 2 to 10 wt%, or 5 to 10 wt%, based on the total weight of the catalyst. For example, in some embodiments, nickel is present in the catalyst in an amount in the range of 0.05 to 7 wt%, e.g., in the range of 0.1 to 7 wt%, or 0.5 to 7 wt%, or 1 to 7 wt%, or 2 to 7 wt%, based on the total weight of the catalyst. In some embodiments, nickel is present in the catalyst in an amount in the range of 0.05 to 5 wt%, e.g., in the range of 0.1 to 5 wt%, or 0.5 to 5 wt%, or 1 to 5 wt%, or 2 to 5 wt%, based on the total weight of the catalyst. For example, in some embodiments of the present disclosure as described herein, nickel is present in the catalyst in an amount in the range of 0.05 to 2 wt%, e.g., in the range of 0.1 to 2 wt%, or 0.3 to 2 wt%, or 0.5 to 2 wt%, based on the total weight of the catalyst. In some embodiments, nickel is present in the catalyst in an amount in the range of 0.05 to 1.5 wt%, e.g., in the range of 0.1 to 1.5 wt%, or 0.3 to 1.5 wt%, or 0.5 to 1.5 wt%, based on the total weight of the catalyst. In some embodiments, nickel is present in an amount in the range of 0.05 to 1 wt%, e.g., in the range of 0.1 to 1 wt%, or 0.3 to 1 wt%, or 0.5 to 1 wt%, based on the total weight of the catalyst. In some embodiments, nickel is present in the catalyst in an amount in the range of 0.05 to 0.8 wt%, e.g., in the range of 0.1 to 0.8 wt%, or 0.3 to 0.8 wt%, or 0.5 to 0.8 wt%, based on the total weight of the catalyst.

As described above, the supported reverse water-gas shift catalysts of the disclosure also include manganese. The present inventors have determined that inclusion of manganese in the catalyst can provide improved performance, as described in the Examples below. For the purposes of this disclosure, the amount of manganese present is calculated as a weight percentage of manganese atoms in the catalyst based on the total weight of the catalyst, despite the form in which that manganese may be present. The manganese may be present in the catalyst in a variety of forms; most commonly, manganese is principally present as metal oxide, metal, or a combination thereof. In various embodiments of the present disclosure as otherwise described herein, manganese is present in the catalyst in an amount in the range of 0.5 to 20 wt%, based on total weight of the catalyst. For example, in various embodiments, manganese is present in the catalyst in an amount in the range of 0.5 to 15 wt%, or 0.5 to 12 wt%, or 0.5 to 10 wt%, based on the total weight of the catalyst. In various embodiments of the present disclosure as described herein, manganese is present in the catalyst in an amount in the range of 1 to 20 wt%, e.g., in the range of 1 to 15 wt%, or 1 to 12 wt%or 1 to 10 wt%, based on the total weight of the catalyst. In various embodiments of the present disclosure as described herein, manganese is present in an amount in the range of 2 to 20 wt%, e.g., in the range of 2 to 15 wt%, or 2 to 12 wt%, or 2 to 10 wt%, based on the total weight of the catalyst. In various embodiments of the present disclosure as described herein, manganese is present in an amount in the range of 4 to 20 wt%, e.g., in the range of 4 to 15 wt%, or 4 to 12 wt%, or 4 to 10 wt%, based on the total weight of the catalyst.

The nickel and the manganese can be provided in a variety of weight ratios. For example, in some embodiments of the present disclosure as described herein, the weight ratio of nickel to manganese present in the catalyst is at least 0.05: 1. For example, in various embodiments, the weight ratio of nickel to manganese is at least 0.1: 1. In various embodiments of the present disclosure as described herein, the weight ratio of nickel to manganese present in the catalyst is at most 5: 1. For example, the weight ratio of nickel to manganese is at most 2: 1, or 1: 1, or 0.5: 1. For example, in various embodiments, the weight ratio of nickel to manganese present in the catalyst is in the range of 0.05: 1 to 5: 1. For example, the weight ratio of nickel to manganese is in the range of 0.05: 1 to 2: 1, or 0.05: 1 to 1: 1, or 0.05: 1 to 0.5: 1, or 0.05: 1 to 0.3: 1, or 0.07: 1 to 5: 1, or 0.07: 1 to 2: 1, or 0.07: 1 to 1: 1, or 0.07: 1 to 0.5: 1, or 0.07: 1 to 0.3: 1, or 0.1: 1 to 5: 1, or 0.1: 1 to 2: 1, or 0.1: 1 to 1: 1, or 0.1: 1 to 0.5: 1, or 0.1: 1 to 0.3: 1.

The present inventors have determined that suitable reverse water-gas shift catalysts can be formed of one or more of cerium oxide, titanium oxide, aluminum oxide, and zirconium oxide as a support, with nickel in combination with manganese included in/on the catalyst. As would be understood by the person of ordinary skill in the art, the amount of cerium, titanium, aluminum, zirconium, nickel, and manganese can be quantified on a metallic basis regardless of the form in which these metals may be present. For example, the amount of these metals can be calculated as a weight percentage based on the total weight of metals in the catalysts (i.e., on a metallic basis) , i.e., without the inclusion of oxygen or non-metallic counterions in the calculation. Accordingly, in various embodiments of the present disclosure as described herein, the total amount of cerium, titanium, aluminum, zirconium, manganese, and nickel in the catalyst is at least 90 wt%, e.g., at least 95 wt%, or at least 98 wt%of the catalyst, on a metallic basis. For example, in some particular embodiments, the total amount of cerium, manganese, and nickel in the catalyst is at least 90 wt%, e.g., at least 95 wt%, or at least 98 wt%of the catalyst, on a metallic basis. In other embodiments, the total amount of titanium, manganese, and nickel in the catalyst is at least 90 wt%, e.g., at least 95 wt%, or at least 98 wt%of the catalyst, on a metallic basis. In other embodiments, the total amount of aluminum, manganese, and nickel in the catalyst is at least 90 wt%, e.g., at least 95 wt%, or at least 98 wt%of the catalyst, on a metallic basis. In other embodiments, the total amount of zirconium, manganese, and nickel in the catalyst is at least 90 wt%, e.g., at least 95 wt%, or at least 98 wt%of the catalyst, on a metallic basis.

As described above, the supported catalyst includes manganese and nickel. Depending on the method of synthesis, these species, which will typically be principally present in metallic form and/or oxide form, can be disposed at a variety of different places on the support. For example, they can be found in pores of the support and on the outer surface of the support. They may be found substantially throughout the support, e.g., as when a large volume of impregnation liquid is used, or only in a surface layer of the support, e.g., when impregnation liquid does not infiltrate into the entirety of the support, such as when using an incipient wetness technique.

Without intending to be bound by theory, it is believed that the active form of nickel is typically a substantially metallic form. As described below, as nickel may be present substantially in an oxide form after catalyst preparation and during shipment and storage, it is typically desirable to activate the catalyst by contacting it with a reductant, e.g., hydrogen gas, to convert a substantial fraction of such oxide to metallic form. However, the person of ordinary skill in the art will appreciate that the present disclosure contemplates the usefulness of a wide variety of nickel forms in its catalysts, as these can be active or can be conveniently transformed to active forms.

The manganese will typically be provided in oxide form after catalyst preparation and during shipment and storage. Without intending to be bound by theory, the present inventors believe that the manganese acts to improve the catalytic activity of the supported nickel catalysts by reducing CO methanation that can occur over the typical reverse water-gas shift reaction temperature range, which impacts CO selectivity. The present inventors believe that the improved activity can be attributed to the manganese interfacing with both the nickel and the support (e.g., cerium oxide, titanium oxide, aluminum oxide, zirconium oxide, or a mixed oxide) . The present inventors contemplate that it is possible that some manganese oxide is converted to metallic form during the activation of the nickel species. However, the person of ordinary skill in the art will appreciate that the present disclosure contemplates the usefulness of a wide variety of manganese forms in its catalysts, as these can provide a promoting effect or can be conveniently transformed to forms that will.

The person of ordinary skill in the art will appreciate that the catalysts of the disclosure can be provided in many forms, depending especially on the particular form of the reactor system in which they are to be used, e.g., in a fixed bed or as a fluid bed. The supports themselves can be provided as discrete bodies of material, e.g., as porous particles, pellets or shaped extrudates, with nickel; and manganese provided thereon to provide the catalyst. However, in other embodiments, a catalyst of the disclosure can itself be formed as a layer on an underlying substrate. The underlying substrate is not particularly limited. It can be formed of, e.g., a metal or metal oxide, and can itself be provided in a number of forms, such as particles, pellets, shaped extrudates, or monoliths. Of course, as would be understood by the person of ordinary skill in the art, other embodiments may be possible.

Another aspect of the present disclosure provides for a method of making the catalyst as described herein. As described above, the method includes providing a support that is a cerium oxide support, a titanium oxide support, an aluminum oxide support, a zirconium oxide support, or a mixed oxide support including a mixture of two or more of cerium oxide, titanium oxide, aluminum oxide, and zirconium oxide; contacting the support with one or more liquids each including one or more nickel-containing compounds and/or one or more manganese-containing compounds dispersed in a solvent; allowing the solvent (s) to evaporate to provide a catalyst precursor; and calcining the catalyst precursor. The person of ordinary skill in the art will appreciate, of course, that other methods can be used to make the catalysts described herein.

In some embodiments of the present disclosure as described herein, contacting the support with the liquid includes adding the liquid in an amount about equal to (i.e., within 25%of, or within 10%of) the pore volume of the support. In other embodiments, contacting the support with the liquid includes adding the liquid in an amount greater than the pore volume of the support. For example, in some embodiments, the ratio of the amount of liquid to the amount of support on a mass basis is in the range of 0.75: 1 to 5: 1, e.g., in the range of 0.9: 1 to 3: 1. In some embodiments, contacting the support with the liquid provides a slurry.

In various embodiments of the present disclosure as described herein, allowing the solvent to evaporate is conducted at ambient temperature. In various embodiments, allowing the solvent to evaporate is conducted at an elevated temperature for a drying time. The person of ordinary skill in the art would be able to select appropriate apparatuses or instruments to allow the solvent to evaporate, and such apparatuses or instruments are not particularly limited. Additionally, the person of ordinary skill in the art would understand that the elevated temperature that will allow the solvent to evaporate depends on the boiling point of the solvent. As such, the person of ordinary skill in the art would be able to select an appropriate elevated temperature. For example, in some embodiments, the elevated temperature is in the range of 50-150℃, e.g., in the range of 50-120℃, or 50-100℃, or 100-150℃, or 100-120℃. In some embodiments, the drying time is in the range of 1 to 48 hours, e.g., in the range of 10 to 36 hours, or 12 to 24 hours. For example, in particular embodiments, the drying time is about 24 hours. In some embodiments, allowing the solvent to evaporate is conducted under vacuum and at an elevated temperature for a drying time, as described herein. In some embodiments, allowing the solvent to evaporate is conducted in a stirring drybath at an elevated temperature, for example, in the range of 30-100℃.

In some embodiments of the present disclosure as described herein, calcining the catalyst precursor is conducted in a furnace for a calcining time and at a calcining temperature. For example, in some embodiments, the calcining time is in the range of 0.5 to 24 hours, or 0.5 to 15 hours, or 0.5 to 10 hours, or 0.5 to 5 hours. In some embodiments, the calcining temperature is in the range of 100-600℃, e.g., in the range of 120-500℃.

As described above, the method of making the catalyst as described herein includes contacting the support with one or more liquids each including one or more nickel-containing compounds and/or one or more manganese-containing compounds dispersed in a solvent. The nickel-and manganese-containing compounds are not particularly limited and the person of ordinary skill in the art would be able to choose appropriate compounds that are soluble in the solvent. For example, in some embodiments of the disclosure as described herein, the nickel-and manganese-containing compounds may be selected from metal salts (e.g., nitrates and acetates) . The solvent is also not particularly limited and the person of ordinary skill in the art would be able to choose an appropriate solvent that can be absorbed by the support. For example, in some embodiments of the disclosure as described herein, the solvent is water. As the person of ordinary skill in the art will appreciate, these metal species are conveniently provided in the same liquid, so that only one step of contacting the support with liquid is required. However, other schemes are possible.

In another aspect, the present disclosure provides a catalyst as described herein made by the methods as described herein.

Another aspect of the present disclosure provides a method for performing a reverse water-gas shift reaction. As described above, the method includes contacting at a temperature in the range of 500-900℃ a catalyst as described herein with a feed stream that includes CO ₂ and H ₂, to provide a product stream that includes CO and H ₂, the product stream having a lower concentration of CO ₂ and a higher concentration of CO than the feed stream. An example of such a method is shown schematically in FIG. 1. In FIG. 1, the method 100 includes performing a reverse water-gas shift reaction by providing a feed stream 111 comprising H ₂ and CO ₂, here, to a reaction zone, e.g., a reactor 110. A reverse water-gas shift catalyst 113, as described herein, is contacted at a temperature in the range of 500-900℃ with the feed stream 111 to provide a product stream 112 comprising CO and H ₂. The product stream has a lower concentration of CO ₂ and a higher concentration of CO than the feed stream.

As used herein, a “feed stream” is used to mean the total material input to a process step, regardless of whether provided in a single physical stream or multiple physical streams, and whether through a single inlet or multiple inlets. For example, H ₂ and CO of the feed stream can be provided to the reverse water-gas shift catalyst in a single physical stream (e.g., in a single pipe to reactor 110) , or in multiple physical streams (e.g., separate inlets for CO and H ₂, or one inlet for fresh CO and H2 and another for recycled CO and/or H2) . Similarly, a “product stream” is used to mean the total material output from a process step, regardless of whether provided in a single physical stream or multiple physical streams, and whether through a single outlet or multiple outlets.

In various embodiments of the present disclosure as described herein, the reverse water-gas shift reaction has a CO selectivity of at least 50%, e.g., of at least 60%, or 70%, or 80%, or 90%. As used herein, a “selectivity” for a given reaction product is the molar fraction of the feed (here, CO ₂) that is converted to the product (for “CO selectivity, ” CO) . The present inventors have determined that the present catalysts, even when operating at lower temperatures than many conventional reverse water-gas shift catalysts, can provide excellent selectivity for CO, despite the potential for competition by the Sabatier reaction and the methanation of CO. For example, in various embodiments of the present disclosure as described herein, the reverse water-gas shift reaction has a CO selectivity in the range of 50-99 wt%. For example, in various embodiments, the reverse water-gas shift reaction has a CO selectivity in the range of 50-90 wt%, or 50-80 wt%, or 50-70 wt%, or 50-60 wt%, or 60-99 wt%, or 60-90 wt%, or 60-80 wt%, or 60-70 wt%, or 70-99 wt%, or 70-90 wt%, or 70-80 wt%.

Notably, the catalysts described herein can be operated to provide carbon monoxide with only a very minor degree of methane formation. For example, in various embodiments of the present disclosure as described herein, the reverse water-gas shift reaction has a methane selectivity of no more than 40%, e.g., no more than 35%, or 30%, or 25%, or 20%. For example, in various embodiments of the present disclosure as described herein, the reverse water-gas shift reaction has a methane selectivity of no more than 10%, e.g., no more than 8%. For example, in various embodiments of the present disclosure as described herein, the reverse water-gas shift reaction has a methane selectivity of no more than 5%, e.g., no more than 4%. For example, in some embodiments, the reverse water-gas shift reaction has a methane selectivity of no more than 2%, e.g., no more than 1%. In some embodiments, the reverse water-gas shift reaction has a methane selectivity of no more than 0.5%, e.g., no more than 0.4%.

The present inventors have determined that the catalysts described here can provide desirably high CO selectivity and desirably low methane selectivity at commercially relevant conversion rates. As used herein, a “conversion” is a molar fraction of a feed that is reacted (be it to desirable products or undesirable species) . In various embodiments of the present disclosure as described herein, the reverse water-gas shift reaction has a CO ₂ conversion of at least 5%, e.g., at least 10%, or 20%. For example, in some embodiments, the reverse water-gas shift reaction has a CO ₂ conversion of at least 30%, e.g., at least 40%, or 50%, or 60%. In various embodiments of the present disclosure as described herein, the reverse water-gas shift reaction has a CO ₂ conversion of no more than 80%, e.g., no more than 70%. For example, in some embodiments, the reverse water-gas shift reaction has a CO ₂ conversion of no more than 65%, e.g., no more than 60%. For example, in various embodiments as otherwise described herein, the CO ₂ conversion is in the range of 10-80%, e.g., 10-70%, or 10-60%, or 10-65%, or 20-80%, or 20-70%, or 20-60%, or 20-65%, or 30-80%, or 30-70%, or 30-60%, or 30-65%, or 40-80%, or 40-70%, or 40-60%, or 40-65%. The person of ordinary skill in the art will, based on the disclosure herein, operate at a degree of conversion that provides a desirable product. And of course, in other embodiments, e.g., when in a stacked-bed or mixed-bed system, the CO ₂ conversion may be even higher than described here.

Advantageously, the processes described herein can be performed at temperatures that are lower than temperatures used in many conventional reverse water-gas shift processes. As described above, various processes of the disclosure can be performed in a temperature range of 500-900℃. For example, in various embodiments of the disclosure as described herein, the method for performing the reverse water-gas shift reaction is conducted at a temperature in the range of 500-850℃, e.g., in the range of 500-800℃, or 500-750℃, or 500-700℃, or 500-650℃, or 500-600℃. In some embodiments, the method for performing the reverse water-gas shift reaction is conducted at a temperature in the range of 550-900℃, e.g., in the range of 550-850℃, or 550-800℃, or 550-750℃, or 550-700℃, or 550-650℃, or 550-600℃. In some embodiments, the method for performing the reverse water-gas shift reaction is conducted at a temperature in the range of 600-900℃, e.g., in the range of 600-850℃, or 600-800℃, or 600-750℃, or 600-700℃, or 600-650℃. In some embodiments, the method for performing the reverse water-gas shift reaction is conducted at a temperature in the range of 650-900℃, e.g., in the range of 650-850℃, or 650-800℃, or 650-750℃, or 650-700℃. In some embodiments, the method for performing the reverse water-gas shift reaction is conducted at a temperature in the range of 700-900℃, e.g., in the range of 700-850℃, or 700-800℃, or 700-750℃.

In some embodiments, the reverse water-gas shift reaction is conducted at a temperature in the range of 200-500℃, e.g., 200-450℃, or 200-400℃, or 200-350℃, or 250-500℃, or 250-450℃, or 250-400℃, or 250-350℃. The present inventors have noted that operation at these temperatures can provide for lower energy demand.

As described above, the feed stream includes CO ₂ and H ₂. Advantageously, the present inventors have recognized that both of these can come from renewable or otherwise environmentally responsible sources. For example, at least part of the H ₂ can be so-called “green” hydrogen, e.g., produced from the electrolysis of water operated using renewable electricity (such as wind, solar, or hydroelectric power) . In other embodiments, at least part of the H ₂ may be from a so-called “blue” source, e.g., from a natural gas reforming process with carbon capture. Of course, other sources of hydrogen can be used in part or in full. For example, in some embodiments, at least a portion of the H ₂ of the feed stream is grey hydrogen, black hydrogen, brown hydrogen, pink hydrogen, turquoise hydrogen, yellow hydrogen, and/or white hydrogen. CO ₂ can be captured from the environment generally, or more directly from processes that form CO ₂ (especially in difficult-to-abate sectors) , making a product that is later made from the CO at least carbon-neutral. For example, in some embodiments, at least part of the CO ₂ is from direct air capture, or from a manufacturing plant such as a bioethanol plant (e.g., CO ₂ produced fermentation) , a steel plant, or a cement plant. Accordingly, the rWGS reaction can be not only carbon neutral, but in some cases a net consumer of carbon dioxide. These benefits in particular makes the rWGS reaction highly attractive for decarbonizing transportation fuels, for both automotive and aviation sectors, since the carbon monoxide produced in the reaction can be readily utilized by well-established technologies to synthesize liquid hydrocarbon fuels.

The feed stream contains both H ₂ and CO ₂ (e.g., provided to a reaction zone in a single physical stream or multiple physical streams) . As used herein, the feed stream includes all feeds to the process, regardless of whether provided as a mixture of gases or as gases provided individually to a reaction zone. In various embodiments as otherwise described herein, the molar ratio of H ₂ to CO ₂ in the feed stream is at least 0.1: 1, e.g., at least 0.5: 1. In some embodiments, the molar ratio of H ₂ to CO ₂ in the feed stream is at least 0.9: 1, e.g., at 1: 1 or least 1.5: 1. In some embodiments, the molar ratio of H ₂ to CO ₂ in the feed stream is at least 2: 1, e.g., at least 2.5: 1. In some embodiments, the molar ratio of H ₂ to CO ₂ in the feed stream is no more than 100: 1, e.g., no more than 75: 1, or 50: 1. In some embodiments, the molar ratio of H ₂ to CO ₂ in the feed stream is no more than 20: 1, e.g., no more than 15: 1, or 10: 1. For example, in some embodiments, the molar ratio of H ₂ to CO ₂ in the feed stream is in the range of0.5: 1 to 10: 1. The person of ordinary skill in the art will provide a desired ratio of H ₂: CO ₂ in the feed stream, based on the disclosure herein, that provides a desirable conversion and selectivity; excess H ₂ can, if consistent with a desirable conversion and selectivity, be provided to flow through the system and provide a product stream with a desirable ratio of H ₂ to CO for a downstream process.

Other gases may also be included in the feed stream. For example, in some embodiments, the feed stream further comprises CO. In some embodiments of the disclosure as otherwise described herein, the feed stream further comprises one or more inert gases. For example, in some embodiments, the feed stream further comprises nitrogen and/or methane.

The processes described herein can be performed at a variety of pressures, as would be appreciated by the person of ordinary skill in the art. In various embodiments of the present disclosure, the method for performing the reverse water-gas shift reaction is conducted at a pressure in the range of 1 to 100 barg. For example, the method is conducted at a pressure in the range of 1 to 70 barg, or 1 to 50 barg, or 1 to 40 barg, or 1 to 35 barg, or 5 to 70 barg, or 5 to 50 barg, or 5 to 40 barg, or 5 to 35 barg, or 10 to 70 barg, 10 to 50 barg, or 10 to 40 barg, or 10 to 35 barg, or 20 to 70 barg, 20 to 50 barg, or 20 to 40 barg, or 20 to 35 barg, or 25 to 70 barg, 25 to 50 barg, or 25 to 40 barg, or 25 to 35 barg.

The processes described herein can be performed at a variety of GHSV (gas hourly space velocity) , as would be appreciated by the person of ordinary skill in the art. As such, the GHSV for performing the reverse water-gas shift reaction is not particularly limited. For example, in some embodiments of the present disclosure, the method for performing the reverse water-gas shift reaction is conducted at a GHSV in the range of 1,000 to 2,000,000 h ^-1. In various embodiments, the method for performing the reverse water-gas shift reaction is conducted at a GHSV in the range of 1,000 to 1,200,000 h ^-1, or 1,000 to 500,000 h ^-1, or 1,000 to 100,000 h ^-1, or 5,000 to 1,200,000 h ^-1, or 5,000 to 500,000 h ^-1, or 5,000 to 100,000 h ^-1, or 10,000 to 1,200,000 h ^-1, or 10,000 to 500,000 h ^-1, or 10,000 to 100,000 h ^-1. In various embodiments of the present disclose, the method for performing the reverse water-gas shift reaction is conducted at a GHSV in the range of 1,000 to 50,000 h ^-1, or 2,000 to 50,000 h ^-1, or 5,000 to 50,000 h ^-1, or 10,000 to 50,000, or 1,000 to 40,000 h ^-1, or 2,000 to 40,000 h ^-1, or 5,000 to 40,000 h ^-1, or 10,000 to 40,000 h ^-1, or 1,000 to 30,000 h ^-1, or 2,000 to 30,000 h ^-1, or 5,000 to 30,000 h ^-1, or 10,000 to 30,000 h ^-1.

The rWGS catalyst described herein is based in part on nickel. It will typically be desirable to activate the rWGS catalyst, e.g., before contacting with the feed stream. Thus in some embodiments of the present disclosure as described herein, the method comprises activating the rWGS catalyst prior to contacting the catalyst with the feed stream. For example, in some embodiments, activating the catalyst comprises contacting the catalyst with a reducing stream comprising a reductive gas, e.g., hydrogen. In various embodiments of the present disclose, the reducing stream comprises hydrogen in an amount of at least 25 mol%, e.g., at least 50 mol%, or 75 mol%, or 90 mol%. The person of ordinary skill in the art will determine suitable conditions for reductive activation of the rWGS catalyst. As such, the person or ordinary skill in the art would be able to choose an appropriate temperature, pressure, and time for activating the rWGS catalyst. For example, in various embodiments activating the catalyst is conducted at a temperature in the range of 200℃ to 800℃. In some embodiment, activating the catalyst is conducted at a temperature in the range of 250℃ to 800℃, or 300℃ to 800℃, or 200℃ to 700℃, or 250℃ to 800℃, or 300℃to 700℃. In some embodiments of the present disclosure as described herein, activating the catalyst provides a catalyst that is at least 10%reduced (e.g., at least 25%, or at least 50%reduced) .

The present inventors have found that contacting the rWGS catalysts as described herein with a feed stream can provide a product stream with advantageously high CO selectivity and low methane selectivity. The amount of CO in the product stream can be further controlled by the rWGS reaction conditions, as described above. But in general, the methods for performing the rWGS reaction as described herein, provide a product stream comprising H ₂ and CO, with the product stream having a lower concentration of CO ₂ and a higher concentration of CO than the feed stream, as is consistent with the degrees of conversion described herein. For example, in various embodiments, the product stream includes no more than 95 mol%CO ₂, or no more than 90 mol%CO ₂. In some embodiments, the product stream includes no more than 85 mol%CO ₂, or no more than 80 mol%CO ₂. In other examples, the product stream includes no more than 75 mol%, or no more than 70 mol%CO ₂. However, as described above, the present inventors have determined that it can be desirable to perform the processes at intermediate degrees of conversion to provide desirably high CO selectivities and desirably low methane selectivities. Accordingly, in various embodiments as otherwise described herein, the product stream includes an amount of CO ₂ together with the CO.

Other gases may also be included in the product stream. In some embodiments of the disclosure as otherwise described herein, the product stream further comprises one or more inert gases. These inert gases may be included from the feed stream or provided from a source other than the feed stream. For example, in some embodiments, the product stream further comprises nitrogen and/or methane.

Depending on, inter alia, the degree of conversion, the CO selectivity, the relative amounts of H ₂ and CO ₂ in the feed stream, and the reaction conditions, the product stream can include H ₂ in combination with CO, in a variety of ratios. For example, in some embodiments, the ratio of H ₂: CO in the product stream is in the range of 0.1: 1 to 100: 1 (e.g., in the range of 0.1: 1 to 50: 1, or 0.1: 1 to 25: 1, or 0.1: 1 to 10: 1, or 0.1: 1 to 5: 1, or 1: 1 to 100: 1, or 1: 1 to 50: 1, or 1: 1 to 25: 1, or 1: 1 to 10: 1, or 1: 1 to 5: 1.

The person of ordinary skill in the art would appreciate that, based on the methods as described herein, the product stream may include H ₂, CO, and CO ₂ and other components in various amounts. Components of the product stream may be separated and used for various purposes in the rWGS process.

For example, in various embodiments of the present disclosure as described herein, the method further comprises separating the product stream to recycle at least a portion (e.g., at least 5 mol%, at least 10 mol%, at least 25 mol%, at least 50 mol%, at least 75 mol%, or at least 90 mol%) of one or more components of the product stream to the feed stream. For example, when the product stream includes CO ₂, the method can include recycling at least a portion (e.g., at least 5 mol%, at least 10 mol%, at least 25 mol%, at least 50 mol%, at least 75 mol%, or at least 90 mol%) of the CO ₂ of the product stream to the feed stream. The product stream may also include H ₂; in some embodiments, the method further includes recycling at least a portion of H ₂ of the product stream (e.g., at least 5 mol%, at least 10 mol%, at least 25 mol%, at least 50 mol%, at least 75 mol%, or at least 90 mol%) to the feed stream.

Such recycling is shown in the process 100 of FIG. 1. Here, the process 100 includes separating from the product stream 112 at least a portion of CO ₂ (stream 114) to recycle to the feed stream 111. Similarly, the process 100 includes separating from the product stream 112 at least a portion of H ₂ (stream 115) to recycle to the product stream 111. While stream 115 is depicted as entering reactor 110 through a different inlet than the rest of the feed stream 111, it is considered to be part of the feed stream, as it is part of the material input to the process step.

As noted above, one competing reaction in the reverse water-gas shift reaction is the Sabatier reaction, which makes methane. While in various embodiments the reverse water-gas shift processes described herein can be performed without forming large amounts of methane, in some embodiments there can be some methane formed. Accordingly, in various embodiments of the method as described herein, the product stream comprises one or more light hydrocarbons. For example, in some embodiments, the product stream may include one or more of methane, ethane, propane, or combinations thereof. As would be understood by the person of ordinary skill in the art, it may be desirable to operate the reverse water-gas shift reaction to provide higher amounts of light hydrocarbons in the product feed. For example, such light hydrocarbons may be inert in further processing of the product stream and so may be acceptable at higher amounts. The person of ordinary skill in the art would be able to select appropriate reaction conditions (e.g., temperature, pressure, feed stream composition) to provide a product stream that includes methane at a desired amount. Accordingly, in various embodiments as otherwise described herein, the product stream includes no more than 40 mol%, or 35 mol%, or 30 mol%, or 25 mol%, or 20 mol%, or 15 mol%, or 10 mol%methane. As noted above, when lower amounts of methane are desired in the product stream, the catalysts of the disclosure can provide very low methane selectivity. For example, in various embodiments, the product stream includes no more than 5 mol%, or 1 mol%, or no more than 0.5 mol%methane.

The light hydrocarbons of the product stream can be separated and used for other purposes. For example, in various embodiments, the method further includes separating at least a portion of one or more light hydrocarbons from the product stream to provide a light hydrocarbon stream. For example, in method 100 of FIG. 1, at least a portion of one or more light hydrocarbons are separated from the product stream 112 to provide a light hydrocarbon stream 116. The light hydrocarbon stream, for example, can be used to provide other products, can be partially oxidized to form CO, can be steam reformed to provide hydrogen, and/or can be burned to provide heat or other energy (e.g., electricity for electrolysis) for use in the rWGS method or otherwise.

The person of ordinary skill in the art will provide the materials and perform the methods described herein based on the general disclosure above, and with reference to the Examples below.

EXAMPLES

The Examples that follow are illustrative of specific embodiments of the catalysts and processes of the disclosure, and various uses thereof. They are set forth for explanatory purposes only, and are not to be taken as limiting the scope of the disclosure.

Example 1. Modelling

The present inventors performed modelling of various equilibrium conditions of the reverse water-gas shift reaction. The predicted carbon dioxide conversion and product composition of the rWGS reaction (Equation 1) in competition with the Sabatier reaction (Equation 3) and the CO methanation reaction (Equation 4) was calculated over the temperature range of 400-800℃, based on thermodynamic equilibrium. From the modeling, the carbon monoxide selectivity increased at temperatures greater than 600℃, while methane selectivity decreased at higher temperatures.

From these results, it is clear that the Sabatier reaction (Equation (3) ) and CO methanation (Equation (4) ) side reactions are exothermic and favored at lower temperatures, while the rWGS reaction (Equation (1) ) is endothermic and favored at higher temperatures. However, other carbon-producing side reactions, not accounted for in this example, can occur at high temperatures. As such, the present inventors have investigated catalysts that operate at middle to high temperatures. These catalysts are discussed in more detail below.

Example2. Catalyst Preparation

A conventional impregnation method was used to prepare catalysts before testing their viability for reverse water-gas shift reactions. The supports used are described in Table 1.

Table 1.

Chemical	Supplier	Pore Volume
Cerium (IV) oxide	Sigma-Aldrich	0.1 mL/g
γ-Alumina	Saint Gobain	0.83 mL/g
Titania P-25 Aeroxide	Evonik	0.5 mL/g
Zirconia SZ 6	Saint Gobain	0.38 mL/g

To prepare the catalyst, a solution of nickel (II) nitrate hexahydrate (purity 99.9985%, VWR) and manganese acetate tetrahydrate (purity 99.9%, Fisher Chemicals) was prepared in deionized water. The solution of nickel and manganese was added to the support powder. The amount of support added is based on the amount of the water on a mass basis so that the ratio of water: support is 3: 1. The slurry was then stirred at room temperature for 4 hours. Excess water was then evaporated using a stirring drybath at a temperature of 60℃. The resulting catalyst precursor powder was then dried for 24 hours at 90℃ in a drying oven.

That catalyst precursor powder was then subjected to calcination by evenly spreading out the powder in a crucible. The crucible is placed in a calcination furnace and the temperature is increased from ambient to 120℃ at a rate of 10℃ per minute. The temperature was then held at 120℃ for 1 hour, and then increased from 120℃ to 500℃ at a rate of 2℃ per minute. The temperature was held at 500℃ for 4 hours, and then cooled to ambient temperature. The resulting catalysts were then tested for its viability for reverse water-gas shift reactions.

Example 3. Performance of Nickel Catalysts

Catalysts prepared as explained in Example 2 were then tested for their catalytic performance for reverse water-gas shift reactions. The catalysts tested were titania supported catalysts that include nickel at 5 wt%with manganese at 0 wt%or 5 wt%. To test the catalytic performance of these catalysts, 20μL of the catalyst diluted with SiC F100 to provide a ratio of 1: 10 was loaded into a 3mm ID ceramic tube reactor, resulting in a 0.22 mL catalyst bed with a zone height of 31.1 mm. Prior to performing the rWGS reaction, the catalysts were activated at 590℃ for 5 hours in a 97%hydrogen and 3%argon atmosphere. Then, the catalysst were contacted at two different temperatures with a feed stream comprising H ₂ and CO ₂ at two different ratios. The total pressure was kept at 10 barg. The GHSV for trials 1 and 2 was 100,000 h ^-1 and for trials 3-6 was 120,000 h ^-1. The catalytic performance was analyzed by detecting the gas composition of the reactor outlet feed using a multi-detector gas chromatograph. The catalytic performance of these catalysts are shown in Table 2. In Table 2, and Tables 3-8 below, the amount of nickel and/or manganese present in the catalyst are shown in parenthesis. These numbers are in weight percent and based on the total weight of the catalyst. For example, CeO ₂Ni (5) Mn (5) corresponds to a catalyst with 5 wt%Ni, 5 wt%Mn, and 90 wt%CeO ₂.

Table 2.

The addition of 5 wt%manganese to the 5 wt%nickel supported on titania resulted in an increase in CO selectivity, albeit with a loss in catalyst activity, as shown by the decrease in CO ₂ conversion.

Catalysts with nickel present in 0.5 wt%, 1 wt%, or 5 wt%, and manganese present in 5 wt%on either titania or ceria supports were tested at 600℃, aH ₂: CO ₂ ratio of 2: 1, a pressure of 30 barg, and a GHSV of 1,200,000 h ^-1. These results are reported in Table 3.

Table 3.

The results of Table 3 indicate that while increasing the nickel content does not improve the selectivity of CO, the CO ₂ conversion is improved.

Example 4. Impact of Support on Catalyst Performance

The impact of the support was also investigated by evaluating nickel and manganese supported catalyst on a variety of catalytic supports (ceria, alumina, titania, and zirconia) . The catalysts contained 5 wt%nickel and 5 wt%manganese. These catalysts were prepared by the method as described in Example 2 and the reactor setup and catalyst activation was used as described in Example 3. These catalysts were contacted at two different temperatures at a pressure of 10 barg, a GHSV of 800,000 h ^-1, and two different H ₂: CO ₂ ratios. The catalytic performance was analyzed by detecting the gas composition of the reactor outlet feed using a multi-detector gas chromatograph. The results are shown in Table 4.

Table 4.

Additionally, these catalysts were contacted at temperature of 700℃ with a feed stream having a H ₂ to CO ₂ ratio of 2: 1, at a pressure of 20 barg, and a GHSV of 800,000 h ^-1. The results are shown in Table 5.

Table 5.

Tables 4 and 5 shows that the performance of nickel manganese supported catalysts are reproduced with a variety of support materials with greater CO selectivity observed at 10 barg and a H ₂: CO ₂ ratio of 1: 1. Methane selectivity increased as the temperature was lowered from 760℃ to 700℃. Afurther increase in methane selectivity was observed when the reaction pressure was doubled to 20 barg at 700℃. Of all supports tested in this work, titania supported nickel manganese catalyst showed the highest CO selectivity at conditions tested, even though it showed the lowest activity out of all supports.

The high selectivity of nickel manganese supported catalysts make them desirable as candidates for middle to high temperature reverse water-gas shift. The high yield and selectivity to CO demonstrated in the trials above provide an effluent stream suitable for integration with other processes.

Example 6. Impact of Catalyst Activation on Catalyst Performance

Catalysts prepared as explained in Example 2 were evaluated for the impact of catalyst activation on catalyst performance. The catalysts used in the study were titania supported catalysts with 5 wt%nickel and 5 wt%manganese, alumina supported catalysts with 5 wt%nickel and 5 wt%manganese, and ceria supported catalysts with 5 wt%nickel and 5 wt%manganese. These supported catalysts were activated in a hydrogen atmosphere at three different temperature (400℃, 590℃, and 760℃) and then used in a rWGS process. To a 3mm ID ceramic tube reactor, 20μL of the catalyst diluted with SiC F100 to provide a ratio of 1: 10 was loaded, resulting in a 0.22 mL catalyst bed with a zone height of 31.1 mm. Activation of the catalyst was carried out using pure H ₂ at a GHSV of 200,000 h ^-1. The reactor pressure was set to 10 barg, followed by heating the reactor to the desired activation temperature at a rate of 1K/min and holding at that temperature for 5 hours. After activation, the reactors were cooled to the temperature for the rWGS process. Four rWGS reaction temperatures, 400℃, 500℃, 600℃, and 700℃, were evaluated. As the rWGS reaction temperature was reached, the feed stream was introduced followed by setting the reaction pressure. The activated catalysts were contacted with a feed stream of H ₂ and CO ₂, present at a mole ratio of 2: 1, at a pressure of 30 barg and a GHSV of 1,200,000 h ^-1. The catalytic performance was analyzed by detecting the gas composition of the reactor outlet feed using a multi-detector gas chromatograph. The results are shown in Tables 6, 7 and 8.

Table 6.

Table 7.

Table 8.

For the titania supported nickel and manganese catalysts, alumina supported nickel and manganese catalysts, and the ceria supported nickel and manganese catalysts, the CO ₂ conversion increases as the reaction temperature increases and is consistent across all activation temperature.

The results of Tables 6-8 show that the activation temperature, reaction temperature, and support type influence the CO selectivity. The CO selectivity of the titania supported nickel and manganese catalysts increases with higher reaction temperatures for activation at both 400℃ and 560℃. However, when activated at 760℃, the CO selectivity generally decreases as reaction temperature increases. For the alumina supported nickel and manganese catalysts, the CO selectivity peaks at a reaction temperature of 500℃ for all activation temperatures, with a higher activation temperature having a higher CO selectivity over all reaction temperatures measured. Similarly, for the ceria supported nickel and manganese catalysts, the CO selectivity peaks at reaction temperatures between 500-600℃ for all activation temperatures, with a higher activation temperature having a higher CO selectivity over all reaction temperatures measured. Overall, the results of Tables 6-8 show that the activation temperature is another variable to adjust the resulting product stream.

Additional aspects of the disclosure are provided by the following enumerated embodiments, which may be combined in any number and in any combination that is not logically or technically inconsistent.

Embodiment 1. A supported reverse water-gas shift catalyst comprising:

Embodiment 2. The catalyst of embodiment 1, wherein the support makes up at least 70 wt% (e.g., at least 75 wt%, or 80 wt%, or 85 wt%, or 90 wt%) of the catalyst, on an oxide basis.

Embodiment 3. The catalyst of embodiment 1 or embodiment 2, wherein the support is a cerium oxide support.

Embodiment 4. The catalyst of embodiment 3, wherein at least a surface layer of the cerium oxide support comprises at least 60 wt%cerium oxide, e.g., at least 70 wt%cerium oxide or at least 80 wt%cerium oxide, on an oxide basis.

Embodiment 5. The catalyst of embodiment 3, wherein at least a surface layer of the cerium oxide support comprises at least 90 wt%cerium oxide, e.g., at least 95 wt%cerium oxide, or at least 98 wt%cerium oxide, on an oxide basis.

Embodiment 6. The catalyst of any of embodiments 3-5, wherein the cerium oxide support comprises at least 50 wt%cerium oxide, e.g., at least 60 wt%cerium oxide, or at least 70 wt%cerium oxide, or at least 80 wt%cerium oxide, on an oxide basis.

Embodiment 7. The catalyst of any of embodiments 3-5, wherein the cerium oxide support comprises at least 90 wt%cerium oxide, e.g., at least 95 wt%cerium oxide, or at least 98 wt%cerium oxide, on an oxide basis.

Embodiment 8. The catalyst of embodiment 1 or embodiment 2, wherein the support is a titanium oxide support.

Embodiment 9. The catalyst of embodiment 8, wherein at least a surface layer of the titanium oxide support comprises at least 60 wt%titanium oxide, e.g., at least 70 wt%titanium oxide, or at least 80 wt%titanium oxide, on an oxide basis.

Embodiment 10. The catalyst of embodiment 8, wherein at least a surface layer of the titanium oxide support comprises at least 90 wt%titanium oxide, e.g., at least 95 wt%titanium oxide, or at least 98 wt%titanium oxide.

Embodiment 11. The catalyst of any of embodiments 8-10, wherein the titanium oxide support comprises at least 50 wt%titanium oxide, e.g., at least 60 wt%titanium oxide, or at least 70 wt%titanium oxide, or at least 80 wt%titanium oxide, on an oxide basis.

Embodiment 12. The catalyst of any of embodiments 8-10, wherein the titanium oxide support comprises at least 90 wt%titanium oxide, e.g., at least 95 wt%titanium oxide, or at least 98 wt%titanium oxide, on an oxide basis.

Embodiment 13. The catalyst of embodiment 1 or embodiment 2, wherein the support is an aluminum oxide support.

Embodiment 14. The catalyst of embodiment 13, wherein at least a surface layer of the aluminum oxide support comprises at least 60 wt%aluminum oxide, e.g., at least 70 wt%aluminum oxide or at least 80 wt%aluminum oxide, on an oxide basis.

Embodiment 15. The catalyst of embodiment 13, wherein at least a surface layer of the aluminum oxide support comprises at least 90 wt%aluminum oxide, e.g., at least 95 wt%aluminum oxide, or at least 98 wt%aluminum oxide, on an oxide basis.

Embodiment 16. The catalyst of any of embodiments 13-15, wherein the aluminum oxide support comprises at least 50 wt%aluminum oxide, e.g., at least 60 wt%aluminum oxide, or at least 70 wt%aluminum oxide, or at least 80 wt%aluminum oxide, on an oxide basis.

Embodiment 17. The catalyst of any of embodiments 13-15, wherein the aluminum oxide support comprises at least 90 wt%aluminum oxide, e.g., at least 95 wt%aluminum oxide, or at least 98 wt%aluminum oxide, on an oxide basis.

Embodiment 18. The catalyst of embodiment 1 or embodiment 2, wherein the support is a zirconium oxide support.

Embodiment 19. The catalyst of embodiment 18, wherein at least a surface layer of the zirconium oxide support comprises at least 60 wt%zirconium oxide, e.g., at least 70 wt%zirconium oxide or at least 80 wt%zirconium oxide, on an oxide basis.

Embodiment 20. The catalyst of embodiment 18, wherein at least a surface layer of the zirconium oxide support comprises at least 90 wt%zirconium oxide, e.g., at least 95 wt%zirconium oxide, or at least 98 wt%zirconium oxide, on an oxide basis.

Embodiment 21. The catalyst of any of embodiments 18-20, wherein the zirconium oxide support comprises at least 50 wt%zirconium oxide, e.g., at least 60 wt%zirconium oxide, or at least 70 wt%zirconium oxide, or at least 80 wt%zirconium oxide, on an oxide basis.

Embodiment 22. The catalyst of any of embodiments 18-20, wherein the zirconium oxide support comprises at least 90 wt%zirconium oxide, e.g., at least 95 wt%zirconium oxide, or at least 98 wt%zirconium oxide, on an oxide basis.

Embodiment 23. The catalyst of embodiment 1 or embodiment 2, wherein the support is a mixed oxide support having at least a surface layer comprising at least 50 wt%of two or more of cerium oxide, titanium oxide, aluminum oxide, and zirconium oxide, on an oxide basis.

Embodiment 24. The catalyst of any of embodiments 1-23, wherein the support does not include additional metals in a total amount of additional metals in excess of 2 wt%, e.g., in excess of 1 wt%or in excess of 0.5 wt%, on an oxide basis.

Embodiment 25. The catalyst of any of embodiments 1-23, wherein the support includes at least one additional metal.

Embodiment 26. The catalyst of embodiment 25, wherein the total amount of the at least one additional metal is in the range of 0.5-20 wt%, e.g., 1-20 wt%, or 2-20 wt%, or 0.5-15 wt%, or 1-15 wt%, or 2-15 wt%, or 0.5-10 wt%, or 1-10 wt%, or 2-10 wt%, or 0.5-5 wt%, or 1-5 wt%, on an oxide basis.

Embodiment 27. The catalyst of any of embodiments 1-26, wherein the support has a pore volume of at least 0.05 mL/g.

Embodiment 28. The catalyst of any of embodiments 1-27, wherein the support has a pore volume of at most 1.5 mL/g.

Embodiment 29. The catalyst of any of embodiments 1-28, wherein the support has a pore volume in the range of 0.05-1.5 mL/g.

Embodiment 30. The catalyst of any of embodiments 1-29, wherein nickel is present in the catalyst in an amount in the range of 0.1 to 10 wt%, e.g., in the range of 0.5 to 10 wt%, or 1 to 10 wt%, or 2 to 10 wt%, or 5 to 10 wt%, based on the total weight of the catalyst.

Embodiment 31. The catalyst of any of embodiments 1-29, wherein nickel is present in the catalyst in an amount in the range of 0.05 to 7 wt%, e.g., in the range of 0.1 to 7 wt%, or 0.5 to 7 wt%, or 1 to 7 wt%, or 2 to 7 wt%, based on the total weight of the catalyst.

Embodiment 32. The catalyst of any of embodiments 1-29, wherein nickel is present in the catalyst in an amount in the range of 0.05 to 5 wt%, e.g., in the range of 0.1 to 5 wt%, or 0.5 to 5 wt%, or 1 to 5 wt%, or 2 to 5 wt%, based on the total weight of the catalyst.

Embodiment 33. The catalyst of any of embodiments 1-29, wherein nickel is present in the catalyst in an amount in a range of 0.05 to 2 wt%, e.g., in the range of 0.1 to 2 wt%, or 0.3 to 2 wt%, or 0.5 to 2 wt%, or 1 to 2 wt%, based on the total weight of the catalyst.

Embodiment 34. The catalyst of any of embodiments 1-29, wherein nickel is present in the catalyst in an amount in a range of 0.05 to 1.5 wt%, e.g., in the range of 0.1 to 1.5 wt%, or 0.3 to 1.5 wt%, or 0.5 to 1.5 wt%, based on the total weight of the catalyst.

Embodiment 35. The catalyst of any of embodiments 1-29, wherein nickel is present in the catalyst in an amount in the range of 0.05 to 1 wt%, e.g., in the range of 0.1 to 1 wt%, or 0.3 to 1 wt%, or 0.5 to 1 wt%, based on the total weight of the catalyst.

Embodiment 36. The catalyst of any of embodiments 1-29, wherein nickel is present in the catalyst in an amount in the range of 0.05 to 0.8 wt%, e.g., in the range of 0.1 to 0.8 wt%, or 0.3 to 0.8 wt%, or 0.5 to 0.8 wt%, based on the total weight of the catalyst.

Embodiment 37. The catalyst of any of embodiments 1-36, wherein manganese is present in the catalyst in an amount in the range of 0.5 to 15 wt%, e.g., in the range of 0.5 to 12 wt%or 0.5 to 10 wt%, based on the total weight of the catalyst.

Embodiment 38. The catalyst of any of embodiments 1-36, wherein manganese is present in the catalyst in an amount in the range of 1 to 20 wt%, e.g., in the range of 1 to15 wt%, or 1 to 12 wt%, or 1 to 10 wt%, based on the total weight of the catalyst.

Embodiment 39. The catalyst of any of embodiments 1-36, wherein manganese is present in the catalyst in an amount in the range of 2 to 20 wt%, e.g., in the range of 2 to15 wt%, or 2 to 12 wt%, or 2 to 10 wt%, based on the total weight of the catalyst.

Embodiment 40. The catalyst of any of embodiments 1-36, wherein manganese is present in the catalyst in an amount in the range of 4 to 20 wt%, e.g., in the range of 4 to 15 wt%, or 4 to 12 wt%, or 4 to 10 wt%, based on the total weight of the catalyst.

Embodiment 41. The catalyst of any of embodiments 1-40, wherein a weight ratio of nickel to manganese is at least 0.05: 1, e.g., at least 0.1: 1.

Embodiment 42. The catalyst of any of embodiments 1-41, wherein a weight ratio of nickel to manganese is at most 5: 1, e.g., at most 2: 1, or 1: 1, or 0.5: 1.

Embodiment 43. The catalyst of any of embodiments 1-42, wherein a ratio of nickel to manganese is in the range of 0.05: 1 to 5: 1 (e.g., in the range of 0.05: 1 to 2: 1, or 0.05: 1 to 1: 1, or 0.05: 1 to 0.5: 1, or 0.05: 1 to 0.3: 1, or 0.07: 1 to 5: 1, or 0.07: 1 to 2: 1, or 0.07: 1 to 1: 1, or 0.07: 1 to 0.5: 1, or 0.07: 1 to 0.3: 1, or 0.1: 1 to 5: 1, or 0.1: 1 to 2: 1, or 0.1: 1 to 1: 1, or 0.1: 1 to 0.5: 1, or 0.1: 1 to 0.3: 1) .

Embodiment 44. The catalyst of any of embodiments 1-43, wherein the total amount of cerium, titanium, aluminum, zirconium, manganese, and nickel in the catalyst is at least 90 wt%, e.g., at least 95 wt%or at least 98 wt%of the catalyst, on a metallic basis.

Embodiment 45. A method for making the catalyst of any of embodiments 1-44, the method comprising:

contacting the support with one or more liquids each comprising one or more nickel- containing compounds and/or one or more manganese-containing compounds dispersed in a solvent (s) ;

allowing the solvent (s) to evaporate to provide a catalyst precursor; and calcining the catalyst precursor.

Embodiment 46. The method of embodiment 45, wherein contacting the support with the liquid comprises adding the liquid in an amount equal to the pore volume of the support.

Embodiment 47. The method of embodiment 45, wherein contacting the support with the liquid comprises adding the liquid in an amount greater than the pore volume of the support.

Embodiment 48. The method of any of embodiments 45-47, wherein ratio of the amount liquid to the amount of support on a mass basis is in the range of 1: 1 to 5: 1 (e.g., in the range of 1: 1 to 3: 1) .

Embodiment 49. The method of any of embodiments 45-48, wherein contacting the support with the liquid provides a slurry.

Embodiment 50. The method of any of embodiments 45-49, wherein allowing the solvent to evaporate is conducted at ambient temperature.

Embodiment 51. The method of embodiments 45-49, wherein allowing the solvent to evaporate is conducted at an elevated temperature (e.g., in the range of 50-150℃) for a drying time (e.g., 24 hours) .

Embodiment 52. The method of embodiments 45-49, wherein allowing the solvent to evaporate is conducted under vacuum and at an elevated temperature (e.g., in the range of 50-150℃) for a drying time (e.g., 24 hours) .

Embodiment 53. The method of any of embodiments 45-49, wherein allowing the solvent to evaporate is conducted in a stirring drybath at an elevated temperature (e.g., in the range of 30-100℃) .

Embodiment 54. The method of any of embodiments 45-53, wherein calcining the catalyst precursor is conducted for a calcining time in the range of 0.5 to 24 hours (e.g., 0.5 to 15 hours, or 0.5 to 10 hours, or 0.5 to 5 hours) .

Embodiment 55. The method of any of embodiments 45-54, wherein calcining the catalyst precursor is conducted for a calcining is in the range of 100-600℃ (e.g., in the range of 120-500℃) .

Embodiment 56. The catalyst of any of embodiments 1-44, made by a method according to embodiments 45-55.

Embodiment 57. A method for performing a reverse water-gas shift reaction, the method comprising:

contacting at a temperature in the range of 500-900℃ a catalyst according to any of embodiments 1-44 and 56 with a feed stream comprising CO ₂ and H ₂, to provide a product stream comprising CO and H ₂, the product stream having a lower concentration of CO ₂ and a higher concentration of CO than the feed stream.

Embodiment 58. The method of embodiment 57, wherein the reverse water-gas shift reaction has a CO selectivity of at least 50%, e.g., of at least 60%, or 70%, or 80%, or 90%.

Embodiment 59. The method of embodiment 57, wherein the reverse water-gas shift reaction has a CO selectivity of in the range of 50-99 w% (e.g., in the range of 50-90 wt%, or 50-80 wt%, or 50-70 wt%, or 50-60 wt%, or 60-99 wt%, or 60-90 wt%, or 60-80 wt%, or 60-70 wt%, or 70-99 wt%, or 70-90 wt%, or 70-80 wt%) .

Embodiment 60. The method of any of embodiments 57-59, wherein the reverse water-gas shift reaction has a methane selectivity of no more than 40%, e.g., no more than 35%, or 30%, or 25%or 20%.

Embodiment 61. The method of any of embodiments 57-59, wherein the reverse water-gas shift reaction has a methane selectivity of no more than 10%, e.g., no more than 8%.

Embodiment 62. The method of any of embodiments 57-59, wherein the reverse water-gas shift reaction has a methane selectivity of no more than 5%, e.g., no more than 4%.

Embodiment 63. The method of any of embodiments 57-59, wherein the reverse water-gas shift reaction has a methane selectivity of no more than 2%, e.g., no more than 1%.

Embodiment 64. The method of any of embodiments 57-59, wherein the reverse water-gas shift reaction has a methane selectivity of no more than 0.5%, e.g., no more than 0.4%.

Embodiment 65. The method of any of embodiments 57-64, having a CO ₂ conversion of at least 5%, e.g., at least 10%, or 20%.

Embodiment 66. The method of any of embodiments 57-64, having a CO ₂ conversion of at least 30%, e.g., at least 40%.

Embodiment 67. The method of any of embodiments 57-66, having a CO ₂ conversion of no more than 80%, e.g., no more than 70%.

Embodiment 68. The method of any of embodiments 57-66, having a CO ₂ conversion of no more than 65%, e.g., no more than 60%.

Embodiment 69. The method of any of embodiments 57-68, conducted at a temperature in the range of 500-850℃, e.g., in the range of 500-800℃, or 500-750℃, or 500-700℃, or 500-650℃, or 500-600℃.

Embodiment 70. The method of any of embodiments 57-68, conducted at a temperature in the range of 550-900℃, e.g., in the range of 550-850℃, or 550-800℃, or 550-750℃, or 550-700℃, or 550-650℃, or 550-600℃.

Embodiment 71. The method of any of embodiments 57-68, conducted at a temperature in the range of 600-900℃, e.g., in the range of 600-850℃, or 600-800℃, or 600-750℃, or 600-700℃, or 600-650℃.

Embodiment 72. The method of any of embodiments 57-68, conducted at a temperature in the range of 650-900℃, e.g., in the range of 650-850℃, or 650-800℃, or 650-750℃, or 650-700℃.

Embodiment 73. The method of any of embodiments 57-68, conducted at a temperature in the range of 700-900℃, e.g., in the range of 700-850℃, or 700-800℃, or 700-750℃.

Embodiment 74. The method of any of embodiments 57-73, wherein at least part of the H ₂ of the feed stream is from a renewable source.

Embodiment 75. The method of any of embodiments 57-74, wherein at least part of the H ₂ of the feed stream is green hydrogen.

Embodiment 76. The method of any of embodiments 57-74, wherein at least part of the H ₂ of the feed stream is blue hydrogen.

Embodiment 77. The method of any of embodiments 57-73, wherein at least a part of the H ₂ of the feed stream is grey hydrogen, black hydrogen, brown hydrogen, pink hydrogen, turquoise hydrogen, yellow hydrogen, and/or white hydrogen.

Embodiment 78. The method of any of embodiments 57-77, wherein at least part of the CO ₂ of the feed stream is from a renewable source.

Embodiment 79. The method of any of embodiments 57-77, wherein at least part of the CO ₂ of the feed stream is from direct air capture.

Embodiment 80. The method of any of embodiments 57-77, wherein at least part of the CO ₂ of the feed stream captured from a manufacturing plant, e.g., a bioethanol plant, a steel plant, or a cement plant.

Embodiment 81. The method of any of embodiments 57-80, wherein the molar ratio of H ₂ to CO ₂ in the feed stream is at least 0.1: 1, e.g., at least 0.5: 1.

Embodiment 82. The method of any of embodiments 57-80, wherein the molar ratio of H ₂ to CO ₂ in the feed stream is at least 0.9: 1, e.g., at least 1: 1 or at least 1.5: 1.

Embodiment 83. The method of any of embodiments 57-80, wherein the molar ratio of H ₂ to CO ₂ in the feed stream is at least 2: 1, e.g., at least 2.5: 1.

Embodiment 84. The method of any of embodiments 57-83, wherein the molar ratio of H ₂ to CO ₂ in the feed stream is no more than 100: 1, e.g., no more than 75: 1, or 50: 1.

Embodiment 85. The method of any of embodiments 57-83, wherein the molar ratio of H ₂ to CO ₂ in the feed stream is no more than 20: 1, e.g., no more than 15: 1, or 10: 1.

Embodiment 86. The method of any of embodiments 57-83, wherein the molar ratio of H ₂ to CO ₂ in the feed stream is in the range of0.5: 1 to 10: 1.

Embodiment 87. The method of any of embodiments 57-86, conducted at a pressure in the range of 1 to 100 barg (e.g., in the range of 1 to 70 barg, or 1 to 50 barg, or 1 to 40 barg, or 1 to 35 barg, or 5 to 80 barg, or 5 to 50 barg, or 5 to 40 barg, or 5 to 35 barg, or 10 to 70 barg, 10 to 50 barg, or 10 to 40 barg, or 10 to 35 barg, or 20 to 70 barg, 20 to 50 barg, or 20 to 40 barg, or 20 to 35 barg, or 25 to 70 barg, 25 to 50 barg, or 25 to 40 barg, or 25 to 35 barg) .

Embodiment 88. The method of any of embodiments 57-87, conducted at a GHSV in the range of 1,000 to 2,000,000 h ^-1 (e.g., in the range of 1,000 to 1,200,000 h ^-1, or 1,000 to 500,000 h ^-1, or 1,000 to 100,000 h ^-1, or 5,000 to 1,200,000 h ^-1, or 5,000 to 500,000 h ^-1, or 5,000 to 100,000 h ^-1, or 10,000 to 1,200,000 h ^-1, or 10,000 to 500,000 h ^-1, or 10,000 to 100,000 h ^-1) .

Embodiment 89. The method of any of embodiments 57-88, wherein the product stream comprises no more than 95 mol%CO ₂ (e.g., no more than 90 mol%CO ₂) .

Embodiment 90. The method of any of embodiments 57-88, wherein the product stream comprises no more than 85 mol%CO ₂ (e.g., no more than 80 mol%CO ₂) .

Embodiment 91. The method of any of embodiments 57-88, wherein the product stream comprises no more than 75 mol%CO ₂ (e.g., no more than 70 mol%CO ₂) .

Embodiment 92. The method of any of embodiments 57-91, wherein the product stream further comprises CO ₂, and wherein the method further comprises recycling at least a portion of the CO ₂ of the product stream to the feed stream.

Embodiment 93. The method of any of embodiments 57-92, wherein the product stream further comprises hydrogen and wherein the method further comprises recycling at least a portion of the hydrogen of the product stream to the feed stream.

Embodiment 94. The method of any of embodiments 57-93, wherein a ratio of H ₂: CO in the product stream is in the range of 0.1: 1 to 100: 1. (e.g., in the range of0.1: 1 to 50: 1, or 0.1: 1 to 25: 1, or 0.1: 1 to 10: 1, or 0.1: 1 to 5: 1, or 1: 1 to 100: 1, or 1: 1 to 50: 1, or 1: 1 to 25: 1, or 1: 1 to 10: 1, or 1: 1 to 5: 1) .

Embodiment 95. The method of any of embodiments 57-94, wherein the product stream comprises no more than 40 mol%methane, e.g., no more than 35 mol%, or 30 mol%, or 25 mol%, or 20 mol%, or 15 mol%methane.

Embodiment 96. The method of any of embodiments 57-94, wherein the product stream comprises no more than 10 mol%methane, e.g., no more than 5 mol%, or 1 mol%, or 0.5 mol%, or 0.1 mol%methane.

Embodiment 97. The method of any of embodiments 57-96, wherein the method comprises activating the catalyst prior to contacting the catalyst with the feed stream.

Embodiment 98. The method of embodiment 97, wherein activating the catalyst comprises contacting the catalyst with a reducing stream comprising a reductive gas (e.g., hydrogen) .

Embodiment 99. The method of embodiment 97 or embodiment 98, wherein the reducing stream comprises hydrogen in an amount of at least 25 mol% (e.g., at least 50 mol%, or 75 mol%, or 90 mol%) .

Embodiment 100. The method of any of embodiments 97-99, wherein activating the catalyst is conducted at a temperature in the range of 300 to 800℃. (e.g., in the range of 400 to 700℃) .

Embodiment 101. The method of any of embodiments 97-100, wherein activating the catalyst provides a catalyst that is at least 10%reduced (e.g., at least 25%, or 50%) .

The particulars shown herein are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of various embodiments of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for the fundamental understanding of the invention, the description taken with the drawings and/or examples making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. Thus, before the disclosed processes and devices are described, it is to be understood that the aspects described herein are not limited to specific embodiments, apparatuses, or configurations, and as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and, unless specifically defined herein, is not intended to be limiting.

The terms “a, ” “an, ” “the” and similar referents used in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

All methods described herein can be performed in any suitable order of steps unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as” ) provided herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

Unless the context clearly requires otherwise, throughout the description and the claims, the words ‘comprise’ , ‘comprising’ , and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to” . Words using the singular or plural number also include the plural and singular number, respectively. Additionally, the words “herein, ” “above, ” and “below” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of the application.

As will be understood by one of ordinary skill in the art, each embodiment disclosed herein can comprise, consist essentially of or consist of its particular stated element, step, ingredient or component. As used herein, the transition term “comprise” or “comprises” means includes, but is not limited to, and allows for the inclusion of unspecified elements, steps, ingredients, or components, even in major amounts. The transitional phrase “consisting of” excludes any element, step, ingredient or component not specified. The transition phrase “consisting essentially of” limits the scope of the embodiment to the specified elements, steps, ingredients or components and to those that do not materially affect the embodiment.

Unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member may be referred to and claimed individually or in any combination with other members of the group or other elements found herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

Some embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Of course, variations on these described embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

Furthermore, it is to be understood that the embodiments of the invention disclosed herein are illustrative of the principles of the present invention. Other modifications that may be employed are within the scope of the invention. Thus, by way of example, but not of limitation, alternative configurations of the present invention may be utilized in accordance with the teachings herein. Accordingly, the present invention is not limited to that precisely as shown and described.

Claims

A supported reverse water-gas shift catalyst comprising:

a support that is a cerium oxide support, a titanium oxide support, an aluminum oxide support, a zirconium oxide support, or a mixed oxide support comprising a mixture of two or more of cerium oxide, titanium oxide, aluminum oxide, and zirconium oxide;

nickel, present in an amount in the range of 0.05 to 10 wt%of the catalyst, based on the total weight of the catalyst; and

manganese, present in an amount in the range of 0.5 to 20 wt%of the catalyst, based on the total weight of the catalyst.
The catalyst of claim 1, wherein the support makes up at least 70 wt%of the catalyst, on an oxide basis.
The catalyst of claim 1, wherein the support is a cerium oxide support.
The catalyst of claim 3, wherein the cerium oxide support comprises at least 90 wt%cerium oxide, on an oxide basis.
The catalyst of claim 1, wherein the support is a titanium oxide support.
The catalyst of claim 5, wherein the titanium oxide support comprises at least 90 wt%titanium oxide, on an oxide basis.
The catalyst of claim 1, wherein the support is an aluminum oxide support or a zirconium oxide support.
The catalyst of claim 1, wherein nickel is present in the catalyst in an amount in the range of 0.1 to 10 wt%, based on the total weight of the catalyst.
The catalyst of claim 1, wherein manganese is present in the catalyst in an amount in the range of 2 to 20 wt%, based on the total weight of the catalyst.
The catalyst of claim 1, wherein a weight ratio of nickel to manganese is at least 0.05: 1.
The catalyst of claim 1, wherein a weight ratio of nickel to manganese is at most 2: 1.
The catalyst of claim 1, wherein a ratio of nickel to manganese is in the range of 0.05: 1 to 1: 1.
The catalyst of claim 1, wherein the total amount of cerium, titanium, aluminum, zirconium, manganese, and nickel in the catalyst is at least 90 wt%, on a metallic basis.
A method for making the catalyst of any of claims 1-13, the method comprising:

providing a support that is a cerium oxide support, a titanium oxide support, an aluminum oxide support, a zirconium oxide support, or a mixed oxide support comprising a mixture of two or more of cerium oxide, titanium oxide, aluminum oxide, and zirconium oxide;

contacting the support with one or more liquids each comprising one or more nickel-containing compounds and/or one or more manganese-containing compounds dispersed in a solvent (s) ;

allowing the solvent (s) to evaporate to provide a catalyst precursor; and

calcining the catalyst precursor.
A method for performing a reverse water-gas shift reaction, the method comprising:

contacting at a temperature in the range of 500-900℃ a catalyst according to any of claims 1-13 with a feed stream comprising CO ₂ and H ₂, to provide a product stream comprising CO and H ₂, the product stream having a lower concentration of CO ₂ and a higher concentration of CO than the feed stream.
The method of claim 15, wherein the reverse water-gas shift reaction has a CO selectivity of at least 50%.
The method of claim 15, wherein the reverse water-gas shift reaction has a methane selectivity of no more than 40%.
The method of any of claims 57-59, wherein the reverse water-gas shift reaction has a methane selectivity of no more than 10%.
The method of claim 15, having a CO ₂ conversion of at least 30%.
The method of claim 15, having a CO ₂ conversion of no more than 80%.
The method of claim 15, conducted at a temperature in the range of 600-800℃.
The method of claim 15, wherein at least part of the H ₂ of the feed stream is from a renewable source.
The method of claim 15, wherein at least part of the CO ₂ of the feed stream is from a renewable source.
The method of claim 15, wherein the molar ratio of H ₂ to CO ₂ in the feed stream is in the range of 0.5: 1 to 10: 1.
The method of claim 15, wherein the product stream comprises no more than 75 mol%CO ₂.
The method of claim 15, wherein the method comprises activating the catalyst prior to contacting the catalyst with the feed stream.