Reverse water-gas shift catalyst and preparation method thereof and reverse water-gas shift method

Abstract

The present invention relates to the technical field of reverse water gas shift, and specifically to a reverse water gas shift catalyst and a preparation method thereof and a reverse water gas shift method, the method comprising: (1) loading a precious metal on a carrier by an impregnation method, first calcining, the carrier being selected from one or more of titanium dioxide, aluminum oxide, zirconium oxide and silicon dioxide; (2) mixing the product of step (1) with cerium dioxide, grinding, second calcining and reducing; the precious metal element content is 0.2-1wt% of the carrier mass; the mass ratio of the product of step (1) to cerium dioxide is 1:0.5-2; the precious metal is selected from one or more of rhodium, ruthenium and palladium. The reverse water gas shift catalyst is prepared by the preparation method of the present invention, and the catalyst has the advantages of high carbon dioxide conversion rate and good carbon monoxide selectivity for reverse water gas shift reaction, and stable catalytic performance.

Description

Technical Field

[0001] The present invention relates to the technical field of reverse water-gas shift, and in particular to a reverse water-gas shift catalyst and a preparation method thereof and a reverse water-gas shift method. Background Art

[0002] Since the Industrial Revolution, the use of fossil fuels has increased rapidly, resulting in a surge in the release of carbon dioxide from combustion. Carbon dioxide is not only a greenhouse gas, but also a non-toxic, cheap, abundant and renewable source of C1 that can be used to produce carbon monoxide and further produce high-value-added chemicals. However, the inherent thermodynamic and kinetic inertness of the carbon dioxide molecule remains a major obstacle. In addition, the reaction network for carbon dioxide utilization is intricate and will form various by-products, thereby reducing selectivity. Therefore, it is imperative to make catalysts that are not only cost-effective and highly active, but also highly selective and long-term stable for the desired products.

[0003] In addition, compared with other transition metals, precious metal-based catalysts are more resistant to carbon deposition and sulfur poisoning. However, the high price of precious metals has seriously affected the cost of industrial application of CO2 conversion. In order to reduce costs, it is necessary to maximize the use of precious metals in catalysts and improve the activity of precious metals in the catalytic process.

[0004] Therefore, the development of a reverse water-gas shift catalyst and its preparation method and application are of great significance for the resource utilization of CO2. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems of short service life and low activity of catalysts in the reverse water-gas shift reaction in the prior art, and to provide a reverse water-gas shift catalyst and a preparation method thereof and a reverse water-gas shift method. The reverse water-gas shift catalyst of the present invention is used for the reverse water-gas shift reaction, has the advantages of high carbon dioxide conversion rate, good carbon monoxide selectivity, and stable catalytic performance.

[0006] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a reverse water gas shift catalyst, the method comprising:

[0007] (1) The noble metal is loaded on the carrier by impregnation method, and the first calcination is performed, wherein the carrier is selected from one or more of titanium dioxide, aluminum oxide, zirconium oxide and silicon dioxide;

[0008] (2) mixing the product of step (1) with cerium dioxide, grinding, second calcining, and reducing;

[0009] The content of precious metal elements is 0.2-1wt% of the carrier mass;

[0010] The mass ratio of the product of step (1) to cerium dioxide is 1:0.5-2;

[0011] The noble metal is selected from one or more of rhodium, ruthenium and palladium.

[0012] A second aspect of the present invention provides a reverse water gas shift catalyst prepared by the preparation method of the present invention.

[0013] A third aspect of the present invention provides a reverse water-gas shift method, the method comprising:

[0014] Hydrogen is contacted with carbon dioxide in the presence of a catalyst, wherein the catalyst comprises a reverse water gas shift catalyst as described in the present invention.

[0015] Through the above technical scheme, the reverse water gas shift catalyst is prepared by the preparation method of the present invention. The catalyst has the advantages of high carbon dioxide conversion rate and good carbon monoxide selectivity when used for the reverse water gas shift reaction, and the catalytic performance is stable.

[0016] The preparation method of the present invention has a simple preparation process and is easy to realize industrial production. DETAILED DESCRIPTION

[0017] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0018] A first aspect of the present invention provides a method for preparing a reverse water gas shift catalyst, the method comprising:

[0019] (1) The noble metal is loaded on the carrier by impregnation method, and the first calcination is performed, wherein the carrier is selected from one or more of titanium dioxide, aluminum oxide, zirconium oxide and silicon dioxide;

[0020] (2) mixing the product of step (1) with cerium dioxide, grinding, second calcining, and reducing;

[0021] The content of precious metal elements is 0.2-1wt% of the carrier mass;

[0022] The mass ratio of the product of step (1) to cerium dioxide is 1:0.5-2;

[0023] The noble metal is selected from one or more of rhodium, ruthenium and palladium. The reverse water gas shift catalyst is prepared by the preparation method of the present invention. The catalyst has the advantages of high carbon dioxide conversion rate and good carbon monoxide selectivity in the reverse water gas shift reaction, and has stable catalytic performance.

[0024] According to a preferred embodiment of the present invention, in step (2), the product of step (1) is mixed and ground with cerium dioxide in the presence of a polar solvent, and the polar solvent is removed before a second calcination and reduction; preferably, the polar solvent is selected from one or more of water, methanol, ethanol, isopropanol, toluene and acetonitrile, more preferably isopropanol; the grinding in the presence of a polar solvent is beneficial to improving the carbon monoxide selectivity and improving the stability of the catalyst.

[0025] According to a preferred embodiment of the present invention, the amount of polar solvent used is 40-120 wt % of the total mass of solids.

[0026] According to a preferred embodiment of the present invention, ceria is selected from one or more of rod-shaped ceria, polyhedral ceria, cubic ceria and amorphous ceria, preferably cubic ceria, which is beneficial to improving carbon monoxide selectivity and improving the stability of the catalyst.

[0027] According to a preferred embodiment of the present invention, titanium dioxide is selected from one or more of P25 titanium dioxide, anatase titanium dioxide, and rutile titanium dioxide, preferably P25 titanium dioxide and / or anatase titanium dioxide, and more preferably P25 titanium dioxide; this is beneficial to improving the selectivity of carbon monoxide and improving the stability of the catalyst.

[0028] In the present invention, the types of precious metals can be selected from a wide range, and all precious metals that can be used for reverse water gas shift can be used in the present invention. According to a preferred embodiment of the present invention, the precious metal is selected from one or more of rhodium, ruthenium and palladium.

[0029] In the present invention, the impregnation method for loading the precious metal on the carrier comprises: contacting a solution containing the precious metal source with the carrier and drying. Preferably, the drying temperature is 60-100°C.

[0030] In the present invention, there is no particular limitation on the type of the precious metal source, and any soluble substance of the precious metal can be used. According to a preferred embodiment of the present invention, the precious metal source is selected from one or more of rhodium nitrate, ruthenium nitrate and palladium nitrate.

[0031] In the present invention, there is no particular limitation on the conditions of the first calcination. According to a preferred embodiment of the present invention, the first calcination conditions include: a calcination temperature of 300-500° C. and a calcination time of 2-6 hours.

[0032] In the present invention, the second calcination condition has a wide range of optional conditions. According to a preferred embodiment of the present invention, the second calcination condition includes: a calcination temperature of 800-1000° C. and a calcination time of 2-16 hours.

[0033] In the present invention, there is no particular limitation on the reduction conditions. The reduction is carried out in a reducing gas atmosphere. According to a preferred embodiment of the present invention, the reduction conditions include: a reduction temperature of 300-400° C. and a reduction time of 0.5-2 h.

[0034] According to a preferred embodiment of the present invention, in the reducing gas atmosphere, the reducing gas is hydrogen, and preferably, the concentration of hydrogen is 5-18V%.

[0035] A second aspect of the present invention provides a reverse water gas shift catalyst prepared by the preparation method of the present invention.

[0036] A third aspect of the present invention provides a reverse water-gas shift method, the method comprising:

[0037] Hydrogen is contacted with carbon dioxide in the presence of a catalyst, wherein the catalyst comprises a reverse water gas shift catalyst as described in the present invention.

[0038] In the present invention, the contact temperature can be selected in a wide range, and conventional reverse water-gas shift temperatures in the art can be used in the present invention. According to a preferred embodiment of the present invention, the contact temperature is 200-400°C.

[0039] In the present invention, the mass space velocity can be selected in a wide range, and the mass space velocity of the conventional reverse water-gas shift in the art can be used in the present invention. According to a preferred embodiment of the present invention, the mass space velocity is 50000-80000 ml / h / g.

[0040] In the present invention, the molar ratio of hydrogen to carbon dioxide can be selected in a wide range. According to a preferred embodiment of the present invention, the molar ratio of hydrogen to carbon dioxide is 1:0.25-2.

[0041] Example 1

[0042] (1) 0.2 g TiO2 (P25 crystal form) was used as a carrier. An aqueous solution of rhodium nitrate and TiO2 were impregnated in equal volumes according to a loading amount of 1% rhodium element, stirred for 4 h, and dried in an oven at 80 °C for 12 h. The dried powder was ground and calcined at 450 °C for 4 h to obtain a precursor catalyst.

[0043] (2) The precursor catalyst and rod-shaped CeO2 were mixed in a mass ratio of 1:1, and 0.4 ml of deionized water was added. The mixture was fully ground and the solvent was evaporated. The ground powder was calcined at 800 °C for 10 h, and the volume space velocity was 48000 ml / h / g in a 10% hydrogen atmosphere. The mixture was reduced at 400 °C for 1 h and then cooled to room temperature.

[0044] Example 2

[0045] (1) 0.2 g of TiO2 (P25 crystal form) was used as a carrier. An aqueous solution of rhodium nitrate and TiO2 were impregnated in equal volumes according to a loading amount of 1% rhodium element, stirred for 4 h, and dried in an oven at 80 °C for 12 h. The dried powder was ground and calcined at 450 °C for 4 h to obtain a precursor catalyst.

[0046] (2) The precursor catalyst and rod-shaped CeO2 were mixed in a mass ratio of 1:1, 0.4 ml of methanol was added, and the mixture was thoroughly ground and the solvent was evaporated; the ground powder was calcined at 800 °C for 10 h, and the volume space velocity was 48000 ml / h / g in a 10% hydrogen atmosphere, and then reduced at 400 °C for 1 h and cooled to room temperature.

[0047] Example 3

[0048] (1) 0.2 g TiO2 (P25 crystal form) was used as a carrier. An aqueous solution of rhodium nitrate and TiO2 were impregnated in equal volumes according to a loading amount of 1% rhodium element, stirred for 4 h, and dried in an oven at 80 °C for 12 h. The dried powder was ground and calcined at 450 °C for 4 h to obtain a precursor catalyst.

[0049] (2) The precursor catalyst and rod-shaped CeO2 were mixed in a mass ratio of 1:1, 0.4 ml of ethanol was added, and the mixture was thoroughly ground and the solvent was evaporated; the ground powder was calcined at 800 °C for 10 h, and the volume space velocity was 48000 ml / h / g in a 10% hydrogen atmosphere, and then reduced at 400 °C for 1 h and cooled to room temperature.

[0050] Example 4

[0051] (1) 0.2 g TiO2 (P25 crystal form) was used as a carrier. An aqueous solution of rhodium nitrate and TiO2 were impregnated in equal volumes according to a loading amount of 1% rhodium element, stirred for 4 h, and dried in an oven at 80 °C for 12 h. The dried powder was ground and calcined at 450 °C for 4 h to obtain a precursor catalyst.

[0052] (2) Mix the precursor catalyst and rod-shaped CeO2 in a ratio of 1:1, add 0.4 ml of isopropanol, grind thoroughly and evaporate the solvent; calcine the ground powder at 800 °C for 10 h, in a 10% hydrogen atmosphere with a volume space velocity of 48,000 ml / h / g, and reduce at 400 °C for 1 h before cooling to room temperature.

[0053] Example 5

[0054] (1) 0.2 g TiO2 (P25 crystal form) was used as a carrier. An aqueous solution of rhodium nitrate and TiO2 were impregnated in equal volumes according to a loading amount of 1% rhodium element, stirred for 4 h, and dried in an oven at 80 °C for 12 h. The dried powder was ground and calcined at 450 °C for 4 h to obtain a precursor catalyst.

[0055] (2) The precursor catalyst and CeO2 rods were mixed in a ratio of 1:1 and then directly ground into a uniform mixture; the ground powder was calcined at 800°C for 10 h, in a 10% hydrogen atmosphere at a volume space velocity of 48,000 ml / h / g, and reduced at 400°C for 1 h before being cooled to room temperature.

[0056] Example 6

[0057] (1) 0.2 g TiO2 (anatase crystal form) was used as a carrier. An aqueous solution of rhodium nitrate and alumina with an equal volume was impregnated according to a loading amount of 1% rhodium element, stirred for 4 h, and dried in an oven at 80 °C for 12 h. The dried powder was ground and calcined at 450 °C for 4 h to obtain a precursor catalyst.

[0058] (2) Mix the precursor catalyst and rod-shaped CeO2 in a ratio of 1:1, add 0.4 ml of isopropanol, grind thoroughly and evaporate the solvent; calcine the ground powder at 800 °C for 10 h, in a 10% hydrogen atmosphere with a volume space velocity of 48,000 ml / h / g, and reduce at 400 °C for 1 h before cooling to room temperature.

[0059] Example 7

[0060] The method of Example 4 is followed, except that in step (2), cubic cerium dioxide is used instead of rod-shaped cerium dioxide, and the remaining conditions are the same as those of Example 4.

[0061] Example 8

[0062] (1) 0.2 g of alumina was used as a carrier. A palladium nitrate aqueous solution and alumina were impregnated in equal volumes according to a loading amount of 0.5% rhodium element, stirred for 4 h, and dried in an oven at 80 °C for 12 h. The dried powder was ground and calcined at 500 °C for 2 h to obtain a precursor catalyst.

[0063] (2) The precursor catalyst and rod-shaped CeO2 were mixed in a mass ratio of 1:2, 0.6 ml of water was added, and the mixture was fully ground and the solvent was evaporated; the ground powder was calcined at 900 °C for 6 h, and the volume space velocity was 48000 ml / h / g in a 10% hydrogen atmosphere, and then reduced at 300 °C for 0.5 h and cooled to room temperature.

[0064] Example 9

[0065] (1) 0.2 g of zirconium oxide was used as a carrier. An aqueous solution of ruthenium chloride and zirconium oxide were impregnated in equal volumes according to a loading amount of 0.2% of rhodium element, stirred for 4 h, and dried in an oven at 80 °C for 12 h. The dried powder was ground and calcined at 300 °C for 6 h to obtain a precursor catalyst.

[0066] (2) The precursor catalyst and rod-shaped CeO2 were mixed in a mass ratio of 1:0.6, 0.2 ml of water was added, and the mixture was fully ground and the solvent was evaporated; the ground powder was calcined at 1000 °C for 10 h, and the volume space velocity was 48000 ml / h / g in a 10% hydrogen atmosphere, and then reduced at 400 °C for 1 h and cooled to room temperature.

[0067] Example 10

[0068] (1) 0.2 g of TiO2 (rutile crystal) was used as a carrier. An aqueous solution of rhodium nitrate and TiO2 were impregnated in equal volumes according to a loading amount of 1% rhodium element, stirred for 4 h, and dried in an oven at 80 °C for 12 h. The dried powder was ground and calcined at 450 °C for 4 h to obtain a precursor catalyst.

[0069] (2) Mix the precursor catalyst and rod-shaped CeO2 in a ratio of 1:1, add 0.4 ml of isopropanol, grind thoroughly and evaporate the solvent; calcine the ground powder at 800 °C for 10 h, in a 10% hydrogen atmosphere with a volume space velocity of 48,000 ml / h / g, and reduce at 400 °C for 1 h before cooling to room temperature.

[0070] Comparative Example 1

[0071] Rhodium nitrate solution and titanium oxide (0.2 g) were dispersed in water at a loading of 1% and stirred for 4 hours. The mixed solution was dried in an oven at 80°C for 12 hours. The powder was then ground and calcined at 800°C for 10 hours to obtain a catalyst.

[0072] Comparative Example 2

[0073] (1) 0.2 g of rod-shaped CeO2 was used as a carrier. An aqueous solution of rhodium nitrate and CeO2 were impregnated in equal volumes according to a loading amount of 1% rhodium element, stirred for 4 h, and dried in an oven at 80 °C for 12 h. The dried powder was ground and calcined at 450 °C for 4 h to obtain a precursor catalyst.

[0074] (2) The precursor catalyst and TiO2 (P25 crystal form) were mixed in a mass ratio of 1:1, and 0.4 ml of deionized water was added. The mixture was thoroughly ground and the solvent was evaporated. The ground powder was calcined at 800 °C for 10 h, and the volume space velocity was 48000 ml / h / g in a 10% hydrogen atmosphere. The mixture was reduced at 400 °C for 1 h and then cooled to room temperature.

[0075] Comparative Example 3

[0076] (1) 0.2 g of rod-shaped CeO2 and 0.2 g of TiO2 (P25 crystal form) were used as carriers. An aqueous solution of rhodium nitrate and a mixture of TiO2 and CeO2 were impregnated in equal volumes at a loading amount of 0.5% rhodium element. The mixture was stirred for 4 h and dried in an oven at 80 °C for 12 h. The dried powder was ground and calcined at 800 °C for 10 h. In a 10% hydrogen atmosphere, the volume space velocity was 48,000 ml / h / g, and the mixture was reduced at 400 °C for 1 h and then cooled to room temperature.

[0077] The catalyst evaluation conditions are as follows: the reaction is carried out in a quartz tube with an inner diameter of 8 mm, the reaction pressure is atmospheric pressure, the reaction temperature is 400°C, the mass space velocity is 72000 ml / h / g, and the molar ratio of H2 to CO2 is 1:1; the test results after 6 hours of reaction are shown in Table 1.

[0078] Table 1

[0079]

[0080] Embodiment 11

[0081] The catalyst was prepared according to the method of Example 4, except that the catalyst evaluation time was extended to 12 hours for evaluation. The test results are shown in Table 2.

[0082] Table 2

[0083]

[0084] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing a reverse water gas shift catalyst, characterized in that: The method includes: (1) The noble metal is loaded on the carrier by impregnation method, and the first calcination is performed, wherein the carrier is selected from one or more of titanium dioxide, aluminum oxide and zirconium oxide; the titanium dioxide is P25 type titanium dioxide and / or anatase type titanium dioxide; (2) in the presence of a polar solvent, mixing and grinding the product of step (1) with cerium dioxide, removing the polar solvent, and then calcining and reducing for the second time; the polar solvent is isopropanol and / or methanol; The content of precious metal elements is 0.2-1wt% of the carrier mass; The mass ratio of the product of step (1) to cerium dioxide is 1:0.5-2; The noble metal is selected from one or more of rhodium, ruthenium and palladium.

2. The preparation method according to claim 1, wherein The amount of polar solvent used is 40-120wt% of the total solid mass.

3. The preparation method according to claim 1 or 2, wherein The cerium dioxide is selected from one or more of rod-shaped cerium dioxide, polyhedral cerium dioxide, cubic cerium dioxide and amorphous cerium dioxide.

4. The preparation method according to claim 1 or 2, wherein: The cerium dioxide is cubic cerium dioxide.

5. The preparation method according to claim 1 or 2, wherein: The first calcination conditions include: a calcination temperature of 300-500° C. and a calcination time of 2-6 hours; and / or The second calcination conditions include: a calcination temperature of 800-1000° C. and a calcination time of 2-16 hours; and / or The reduction conditions include: a reduction temperature of 300-400°C and a reduction time of 0.5-2 h.

6. The preparation method according to claim 1 or 2, wherein: The impregnation method for loading the precious metal on the carrier includes: contacting a solution containing the precious metal source with the carrier and drying.

7. The reverse water gas shift catalyst prepared by the preparation method according to any one of claims 1 to 6.

8. A reverse water-gas shift method, characterized in that: The method comprises: contacting hydrogen with carbon dioxide in the presence of a catalyst, wherein the catalyst comprises the reverse water gas shift catalyst of claim 7.

9. The reverse water gas shift method according to claim 8, wherein: The contact temperature is 200-400°C; and / or Space velocity is 50000-80000 mL / (h·g); and / or The molar ratio of hydrogen to carbon dioxide is 1:0.25-2.

Images