Reverse water vapor shift catalyst as well as preparation method and application thereof

Abstract

The invention provides a reverse water vapor shift catalyst and a preparation method and application thereof. The catalyst provided by the invention not only has good catalytic activity, but also has good anti-methanation performance and anti-hydration stability. The preparation method comprises the following steps: (1) carrying out first roasting on an Al2O3 matrix doped with TiO2, then placing the Al2O3 matrix in an alkaline solution for heating treatment, and carrying out second roasting after drying to obtain a carrier precursor; (2) impregnating the carrier precursor obtained in the step (1) in an Mg salt solution, drying, and carrying out third roasting to obtain a carrier loaded with MgO; and (3) impregnating the carrier in the step (2) with an impregnation liquid containing Ni and Mo, drying, and carrying out fourth roasting to obtain the reverse water vapor shift catalyst.

Description

Technical Field

[0001] The present invention relates to the technology for preparing CO 2 and H 2 by the reverse water gas shift reaction, and particularly relates to a reverse water gas shift catalyst, a preparation method thereof and an application thereof. Background Art

[0002] The resource utilization of carbon dioxide is one of the effective ways to reduce carbon emissions. As one of the paths for catalytic conversion of carbon dioxide, the reverse water gas shift technology (RWGS) can convert CO 2 into valuable CO, and then synthesize fuels and chemicals with H 2 The reverse water gas shift reaction is a strongly endothermic reaction. The higher the temperature, the more favorable the reaction is and the higher the equilibrium conversion rate is. However, under high-temperature reaction conditions, due to the gasification reaction of CO, the catalyst carbon deposition is serious. If the reaction is carried out at low temperature, restricted by the reaction kinetics, the chemical reaction rate decreases, and the activity requirement for the catalyst is very high. At the same time, as a strongly endothermic reaction, to solve the heat supply problem of the reactor, a shell-and-tube reactor needs to be used, which has certain requirements for the filling of the catalyst and needs to be easy to load and unload.

[0003] The reverse water gas shift catalysts studied more in the academic community can be divided into supported metal catalysts, oxide catalysts and transition metal carbide catalysts. Supported metal catalysts are divided into noble metal catalysts and non-noble metal catalysts. Noble metal catalysts have good catalytic activity in the RWGS reaction, but their industrial applications are limited due to their high prices. In recent years, the non-noble metal catalysts mainly used in the research of the RWGS reaction are Ni, Fe, Cu, etc. The main disadvantages of non-noble metal catalysts applied to the RWGS reaction are serious methanation side reactions, etc. Oxide catalysts have good reverse water gas shift activity, but are much lower than that of metal catalysts. Their characteristic is that they do not have the dissociative adsorption function of CO 2 plus H 2 The generated CO will not be further hydrogenated to form methane, so the methanation side reaction problem can be solved. Transition metal carbides have certain characteristics of metal catalysts, but the preparation process is complex, the cost is high, and it is not easy to be scaled up industrially. Summary of the Invention

[0004] The present invention provides a reverse water gas shift catalyst, a preparation method thereof and an application thereof. The catalyst provided by the present invention not only has good catalytic activity in the application of preparing CO 2 and H 2 by the reverse water gas shift reaction, but also can take into account good anti-methanation performance and anti-hydration stability.

[0005] To achieve its purpose, the present invention provides the following technical solutions:

[0006] On the one hand, the present invention provides a method for preparing an inverse water gas shift catalyst, comprising the following steps:

[0007] (1) First, calcine the Al 2 matrix doped with TiO 2 O 3 , then place it in an alkaline solution and heat-treat it at 180 - 200 °C. After drying, perform a second calcination to obtain a support precursor;

[0008] (2) Impregnate the support precursor obtained in step (1) with a Mg salt solution. After drying, perform a third calcination to obtain a support loaded with MgO;

[0009] (3) Impregnate the support obtained in step (2) with an impregnating solution containing Ni and Mo. After drying, perform a fourth calcination to obtain an inverse water gas shift catalyst loaded with NiO and MoO 3 ;

[0010] Wherein, in the inverse water gas shift catalyst, each component contains the following weight percentages: NiO 0.5 - 1.5%, MoO 3 5.0 - 10.0%, MgO 3.0 - 5.0%, TiO 2 5.0 - 5.5%, Al 2 O 3 78.5 - 86.0%, and the weight ratio of the NiO to the MoO 3 is 0.1 - 0.15.

[0011] The present invention uses an Al 2 matrix doped with TiO 2 O 3 as the support raw material, immerses it in an alkali solution for high-temperature heat treatment, modifies it by loading MgO after calcination, and then loads the active components NiO and MoO 3 on this support in one step to obtain a catalyst with the content of each component in a specific range. The obtained catalyst has good catalytic activity in the preparation of CO from CO 2 and H 2 through the inverse water gas shift, and can take into account better anti-methanation performance and anti-hydration stability. By preparing the catalyst through the preparation method of the present invention, before loading NiO and MoO 3 , loading MgO first can improve the catalyst strength, and a catalyst with significantly improved anti-hydration stability in the preparation of CO from CO 2 and H 2 through the inverse water gas shift can be obtained without loading a large amount of MgO (weight content is 3.0 - 5.0%). Through the preparation method of the present invention, using an Al 2 matrix doped with TiO 2 O3 The matrix is ​​the carrier raw material, which is loaded with MgO after high temperature treatment with alkali solution, and then impregnated with NiO and MoO in the next step. 3 , which can obtain good CO at relatively low NiO content 2 / H 2 Catalytic activity for the production of CO via reverse water gas shift.

[0012] In the present invention, in step (1), the 2 Al 2 O 3 The matrix is ​​a carrier raw material. Before loading other components, it is preheated at 180-200°C in an alkaline solution and calcined after drying. The TiO 2 The inventors found that by doping with TiO 2 Al 2 O 3 The substrate is heated at high temperature in the alkaline solution to significantly improve the specific surface area of ​​the support, thereby significantly improving the performance of the resulting catalyst in catalyzing CO 2 / H 2 In addition, the inventors found that the TiO 2 Al 2 O 3 The matrix is ​​the carrier raw material and controls the TiO content in the final catalyst. 2 The content is 5.0-5.5%, compared with the undoped TiO 2 Al 2 O 3 matrix or compared to TiO alone 2 Support or compared to TiO 2 Catalysts whose contents do not meet the above requirements have significantly improved anti-methanation performance and are conducive to taking into account good reverse water gas shift activity.

[0013] Preferably, in step (1), the alkaline solution is a urea aqueous solution or an ethylenediamine aqueous solution; preferably, the mass concentration of the alkaline solution is 15-25%; the preferred alkaline solution is used to treat the TiO 2 Al 2 O 3 The substrate is treated to obtain a better catalyst support improvement effect and to further improve the performance of the final catalyst. Specifically, there is no particular restriction on the specific amount of the alkaline solution. The minimum amount is at least enough to make the TiO doped 2 Al 2 O 3 The substrate is immersed in an alkaline solution. The heating treatment in step (1) can be performed in a pressure vessel.

[0014] Preferably, in step (1), the time of the heat treatment is 18 - 24 h; the drying in step (1) can be carried out in an oven, for example.

[0015] Preferably, in step (1), the temperature of the first calcination is 500 - 600 °C, and the calcination time is preferably 4 - 6 h.

[0016] Preferably, in step (1), the temperature of the second calcination is 500 - 600 °C, and the calcination time is preferably 2 - 3 h.

[0017] Preferably, in step (2), the temperature of the third calcination is 500 - 600 °C, and the calcination time is preferably 2 - 3 h.

[0018] In some embodiments, in step (2), the Mg salt in the Mg salt solution is Mg(NO 3 ) 2 ·6H 2 O and / or Mg(CH 3 COO) 2 ·4H 2 O. Specifically, the Mg salt solution is, for example, an aqueous solution of Mg salt. Specifically, the amount of the Mg salt solution is based on the ability to achieve impregnation and enable the final obtained catalyst to contain the required content of MgO.

[0019] In some embodiments, in step (2), the impregnation is carried out by the equal - volume impregnation method.

[0020] The inventors of the present invention found that when preparing the catalyst of the present invention, by impregnating and loading Ni and Mo in one - step method compared with loading Ni and Mo separately in two - step method, the obtained catalyst has significantly improved catalytic performance in the preparation of CO 2 / H 2 by reverse water - gas shift to prepare CO. Preferably, in step (3), the preparation steps of the impregnating solution containing Ni and Mo include: mixing nickel basic carbonate and citric acid evenly in water, and then heating to evaporate water, preferably heating to evaporate until it becomes paste - like or semi - solid; after cooling, adding ammonia water to dissolve to obtain a transparent solution, and then adding ammonium molybdate to the transparent solution and stirring to dissolve to obtain the impregnating solution containing Ni and Mo. The inventors of the present invention found that when preparing the impregnating solution containing Ni and Mo, first reacting nickel basic carbonate with citric acid to form nickel citrate, and then using ammonia water as a solvent to dissolve nickel citrate and ammonium molybdate can obtain a uniform impregnating solution, which is beneficial to the uniform loading of each component and beneficial to improving the catalytic performance of the finally prepared catalyst; while if using soluble nickel salt (such as nickel nitrate), it is difficult to form a homogeneous solution with ammonium molybdate, and precipitates will be generated, resulting in difficulty in implementing the synchronous loading of Mo and Ni and difficulty in preparing the required catalyst.

[0021] In some embodiments, the amount of citric acid used is, for example, 1.25 - 1.75 times the weight of nickel basic carbonate. The ammonia water is, for example, ammonia water with a mass concentration of 13 - 17%. There is no particular limitation on the amount of ammonia water used, as long as the purpose of dissolution and equal - volume impregnation can be achieved.

[0022] More preferably, the ammonium molybdate is selected from (NH 4 ) 6 Mo 7 O 24 ·4H 2 O and / or (NH 4 ) 2 Mo 4 O 13 ·2H 2 O.

[0023] Preferably, in step (3), the temperature of the fourth calcination is 500 - 600 °C, and the calcination time is preferably 2 - 3 h.

[0024] In some embodiments, in step (3), the impregnation is carried out by the equal - volume impregnation method.

[0025] Preferably, the Al 2 O 3 substrate is Al 2 O 2 spheres doped with TiO 3 , preferably with a particle size of 3 - 5 mm. Commercially available products can be directly used. In the present invention, there is no particular limitation on the weight content of TiO 2 O 3 in the Al 2 substrate used, as long as the final obtained catalyst contains 78.5 - 86.0 wt% of Al 2 O 3 and 5.0 - 5.5 wt% of TiO 2 . For example, in some embodiments, the Al 2 O 3 substrate used is doped with 5 - 8 wt% of TiO 2 . The reverse water - gas shift reaction is a strongly endothermic reaction, and heat is supplied by a shell - and - tube reactor. The present invention preferably uses Al 2 O 3 spheres as raw materials to prepare the catalyst, and the finally obtained catalyst has the characteristic of being convenient to disassemble.

[0026] On the other hand, the present invention provides a reverse water - gas shift catalyst. Based on the total weight of the catalyst, the catalyst contains the following components in weight percentages:

[0027] NiO 0.5 - 1.5%, MoO 35.0 - 10.0%, MgO 3.0 - 5.0%, TiO 2 5.0 - 5.5%, Al 2 O 3 78.5 - 86.0%, and the weight ratio of the NiO and the MoO 3 is 0.1 - 0.15;

[0028] Preferably, the catalyst is prepared by the preparation method described above.

[0029] On the other hand, the present invention provides a reverse water gas shift catalyst, the catalyst comprising a carrier and NiO and MoO supported on the carrier 3 , the carrier comprising a carrier precursor and MgO supported on the carrier precursor, the carrier precursor being an Al doped with TiO 2 matrix; 2 O 3 ;

[0030] Based on the total weight of the catalyst, the content of the NiO is 0.5 - 1.5%, the content of the MoO 3 is 5.0 - 10.0%, the content of the MgO is 3.0 - 5.0%, the content of the TiO 2 is 5.0 - 5.5%, the content of the Al 2 O 3 is 78.5 - 86.0%, and the weight ratio of the NiO and the MoO 3 is 0.1 - 0.15;

[0031] Preferably, the catalyst is prepared by the preparation method described above.

[0032] The reverse water gas shift catalyst provided by the present invention is applied in the preparation of CO 2 and H 2 through the reverse water gas shift reaction, has good catalytic activity, and can take into account good anti-methanation performance and anti-hydration stability.

[0033] In the catalyst provided by the present invention, specific contents of NiO and MoO are introduced simultaneously 3 , specifically controlling the content of NiO to 0.5 - 1.5 wt%, the content of MoO 3 to 5.0 - 10.0 wt%, and controlling the weight ratio of NiO and MoO 3 to 0.1 - 0.15. Compared with the case of introducing only the Ni component or only the Mo component separately, and compared with the catalyst with too high or too low weight ratio of NiO and MoO 3 , in the catalytic CO 2 / H 2It has better catalytic performance in the preparation of CO by reverse water gas shift, which is conducive to taking into account both better reverse water gas shift activity and anti-methanation performance.

[0034] In another aspect, the present invention also provides an application, wherein the catalyst prepared by the preparation method described above or the catalyst described above is used to catalyze CO 2 and H 2 It is used in the process of preparing CO through the reverse water gas shift reaction.

[0035] Furthermore, the catalyst is reduced before use; preferably, the conditions for the reduction include: a temperature of 350-400° C., a reducing atmosphere of a mixture of hydrogen and nitrogen, preferably the volume percentages of the hydrogen and nitrogen are 10-20% and 80-90% respectively, and a reaction pressure of 0.1-1.0 MPa. The reduction allows Ni to exist in the form of a metal element and Mo to exist in the form of an oxide.

[0036] The technical solution provided by the present invention has the following beneficial effects:

[0037] In the present invention, alumina doped with TiO2 is used as a carrier raw material and heat-treated in an alkaline solution. Compared with the use of activated alumina without TiO2, the catalyst prepared by the present invention has significantly better anti-methanation performance and good catalytic activity. At the same time, based on the TiO2-Al2O3 carrier precursor of the present invention and loaded with MgO auxiliary agent for modification, significantly improved anti-hydration stability can be obtained at a lower MgO content. Furthermore, the active components NiO and MoO3 are loaded by a single impregnation method, and the contents of the two are controlled within a specific range, and combined with other components in the catalyst, not only the reverse water vapor shift activity of the catalyst is improved, but also the methanation activity of the catalyst is inhibited. The catalyst provided by the present invention has a good performance in CO 2 and H 2 It has good catalytic activity in the preparation of CO through the reverse water gas shift reaction, and has good anti-methanation performance and anti-hydration stability. DETAILED DESCRIPTION

[0038] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The term "and / or" as may be used herein includes any and all combinations of one or more of the related listed items. The terms "first", "second", "third", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

[0040] For the parts where specific experimental procedures or conditions are not specified in the examples and comparative examples, the operations or conditions of the corresponding conventional experimental procedures in this technical field can be followed. For the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0041] TiO 2 -Al 2 O 3 The spherical carrier was purchased from Zibo Guanqiao Economic and Trade Co., Ltd., with a TiO 2 content of 6% by weight and a particle size of 4 mm.

[0042] Other raw materials were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0043] The muffle furnace was purchased from Thermo Scientific, model FD1500.

[0044] The composition of the catalyst was determined by a ZSX Primus II type X-ray fluorescence spectrometer (XRF) from Rigaku Corporation.

[0045] The reverse water gas shift model reaction evaluation device was purchased from BOLUMING (Beijing) Technology Co., Ltd.

[0046] Example 1:

[0047] The reverse water gas shift catalyst was prepared through the following steps:

[0048] (1) Weigh 83.5 g of TiO 2 -Al 2 O 3 spherical carriers, calcine them at 500 °C for 6 h, and the specific surface area is 98.5 m 2 / g.

[0049] Then put the TiO 2 -Al 2 O 3 spherical carriers into a pressure bomb, add 150 g of urea aqueous solution with a mass concentration of 20%, place it in an oven at 180 °C and let it stand still for 24 h. After cooling, filter out the spherical carriers, dry them in an oven at 120 °C for 2 h, and then calcine them at 500 °C for 3 h to obtain the precursor of the carrier, whose specific surface area is 228.5 m 2 / g.

[0050] (2) Dissolve 31.8 g of Mg(NO 3 ) 2 ·6H 2 O in 15 g of deionized water to obtain a Mg salt solution.

[0051] The Mg salt solution was impregnated onto the carrier precursor in step (1), dried at 100 °C for 3 h, and calcined at 500 °C for 3 h to obtain a carrier loaded with MgO.

[0052] (3) 2.9 g of nickel basic carbonate and 4.4 g of citric acid were placed in 20 g of deionized water, stirred and evaporated on a heating table at 150 °C until it became semi-solid, cooled to room temperature, 15 g of an ammonia water solution with a mass concentration of 15% was added and stirred until dissolved to obtain a transparent solution, and then 12.3 g of (NH 4 )6Mo 7 O 24 ·4H 2 O was dissolved by stirring at room temperature, and the ammonia water solution with a mass concentration of 15% was continuously added to make the volume up to 33 ml to prepare a nickel-molybdenum impregnation solution;

[0053] The nickel-molybdenum impregnation solution was impregnated onto the carrier obtained in step (2), dried at 100 °C for 3 h, and calcined at 500 °C for 3 h to obtain a catalyst product in the form of an oxide. The composition of this catalyst is as follows: the contents of NiO, MoO 3 , MgO, TiO 2 and Al 2 O 3 are 1.5 wt%, 10.0 wt%, 5.0 wt%, 5.0 wt% and 78.5 wt% respectively.

[0054] Example 2:

[0055] The reverse water gas shift catalyst was prepared through the following steps:

[0056] (1) Weigh 91.5 g of TiO 2 -Al 2 O 3 pellets carrier, calcine at 600 °C for 4 h, and the specific surface area is 81.2 m 2 / g.

[0057] Then the TiO 2 -Al 2 O 3 pellets carrier was loaded into a pressure bomb, 150 g of an ethylenediamine aqueous solution with a mass concentration of 20% was loaded, placed in an oven at 200 °C and left statically for 18 h. After cooling, the pellets carrier was filtered out, dried in an oven at 100 °C for 3 h, and then calcined at 600 °C for 2 h to obtain a carrier precursor, whose specific surface area is 249.5 m 2 / g.

[0058] (2) 19.1 g of Mg(NO 3 ) 2 ·6H 2 O was dissolved in 20 g of deionized water to obtain a Mg salt solution.

[0059] Impregnate the Mg salt solution onto the carrier precursor obtained in step (1), dry it at 110 °C for 2.5 h, and calcine it at 600 °C for 2 h to obtain a carrier loaded with MgO.

[0060] (3) Put 1.0 g of nickel basic carbonate and 1.5 g of citric acid into 20 g of deionized water, stir and evaporate on a heating table at 150 °C until it becomes semi-solid, cool to room temperature, add 15 g of ammonia water with a mass concentration of 15%, stir and dissolve to obtain a transparent solution, and continue to add 6.1 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O and dissolve it by stirring at room temperature. Then continue to add ammonia water with a mass concentration of 15% to make the volume up to 34 ml to prepare a nickel-molybdenum impregnation solution;

[0061] Impregnate the nickel-molybdenum impregnation solution onto the carrier obtained in step (2), dry it at 120 °C for 2 h, and calcine it at 600 °C for 2 h to obtain a catalyst product in the form of an oxide. The composition of this catalyst is: NiO, MoO 3 , MgO, TiO 2 and Al 2 O 3 The contents are 0.5 wt%, 5.0 wt%, 3.0 wt%, 5.5 wt% and 86.0 wt% in sequence.

[0062] Example 3

[0063] Prepare a reverse water gas shift catalyst through the following steps:

[0064] (1) Weigh 87.6 g of TiO 2 -Al 2 O 3 spherical carriers, calcine them at 550 °C for 5 h, and the specific surface area is 90.5 m 2 / g.

[0065] Then put the TiO 2 -Al 2 O 3 spherical carriers into a pressure bomb, add 150 g of urea aqueous solution with a mass concentration of 20%, put it in an oven at 190 °C and let it stand still for 21 h. After cooling, filter out the spherical carriers, dry them in an oven at 110 °C for 2.5 h, and then calcine them at 550 °C for 2.5 h to obtain a carrier precursor, whose specific surface area is 232.3 m 2 / g.

[0066] (2) Put 25.4 g of Mg(NO 3 ) 2 ·6H 2O is dissolved in 17.5 g of deionized water to obtain a Mg salt solution.

[0067] The Mg salt solution is impregnated on the carrier precursor of step (1), dried at 120 °C for 2 h, and calcined at 550 °C for 2.5 h to obtain a carrier loaded with MgO.

[0068] (3) 1.8 g of nickel basic carbonate and 2.7 g of citric acid are placed in 20 g of deionized water, stirred and evaporated on a heating table at 150 °C until it becomes semi-solid, cooled to room temperature, 15 g of an ammonia water solution with a mass concentration of 15% is added and stirred to dissolve to obtain a transparent solution, and 9.2 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O is dissolved with stirring at room temperature, and the ammonia water solution with a mass concentration of 15% is continuously added to make the volume up to 32.5 ml to prepare a nickel-molybdenum impregnation solution;

[0069] The nickel-molybdenum impregnation solution is impregnated on the carrier obtained in step (2), dried at 110 °C for 2.5 h, and calcined at 550 °C for 2.5 h to obtain a catalyst product in the form of an oxide. The composition of this catalyst is: NiO, MoO 3 , MgO, TiO 2 and Al 2 O 3 The contents are 0.9 wt%, 7.5 wt%, 4.0 wt%, 5.3 wt% and 82.3 wt% in sequence.

[0070] Example 4

[0071] The reverse water gas shift catalyst is prepared through the following steps:

[0072] (1) Weigh 87.6 g of TiO 2 -Al 2 O 3 pellets carrier, calcine at 600 °C for 6 h, and the specific surface area is 80.5 m 2 / g.

[0073] Then the TiO 2 -Al 2 O 3 pellets carrier is loaded into a pressure bomb, 150 g of a urea aqueous solution with a mass concentration of 20% is loaded, placed statically in an oven at 200 °C for 24 h, the pellets carrier is filtered out after cooling, dried in an oven at 120 °C for 3 h, and then calcined at 600 °C for 3 h to obtain a carrier precursor, and its specific surface area is 208.7 m 2 / g.

[0074] (2) 21.3 g of Mg(CH 3 COO)2 ·4H 2 O was dissolved in 18 g of deionized water to obtain a Mg salt solution.

[0075] The Mg salt solution was impregnated on the carrier precursor of step (1), dried at 120 °C for 2 h, and calcined at 550 °C for 2.5 h to obtain a carrier loaded with MgO.

[0076] (3) 1.8 g of nickel basic carbonate and 2.7 g of citric acid were placed in 20 g of deionized water, stirred and evaporated on a heating table at 150 °C until semi-solid, cooled to room temperature, 15 g of an ammonia water solution with a mass concentration of 15% was added and stirred to dissolve to obtain a transparent solution, and 8.6 g of (NH 4 ) 2 Mo 4 O 13 ·2H 2 O was dissolved with stirring at room temperature, and the ammonia water solution with a mass concentration of 15% was continuously added to make up the volume to 32 ml to prepare a nickel-molybdenum impregnation solution;

[0077] The nickel-molybdenum impregnation solution was impregnated on the carrier obtained in step (2), dried at 110 °C for 2.5 h, and calcined at 550 °C for 2.5 h to obtain a catalyst product in the form of an oxide. The composition of this catalyst is: NiO, MoO 3 , MgO, TiO 2 and Al 2 O 3 The contents were 0.9 wt%, 7.5 wt%, 4.0 wt%, 5.3 wt% and 82.3 wt% in sequence.

[0078] Comparative Example 1 (compared with Example 3, TiO was not incorporated into the carrier 2 )

[0079] The reverse water gas shift catalyst was prepared by the following steps:

[0080] (1) Weighed 87.6 g of Al 2 O 3 spherical carriers (without TiO 2 ), calcined at 500 °C for 4 h, and the specific surface area was 212.9 m 2 / g.

[0081] (2) Then 21.3 g of Mg(CH 3 COO) 2 ·4H 2 O was dissolved in 18 g of deionized water to obtain a Mg salt solution.

[0082] The Mg salt solution was impregnated on the carrier of step (1), dried at 120 °C for 2 h, and calcined at 550 °C for 2.5 h to obtain a carrier loaded with MgO.

[0083] (3) Put 1.8 g of nickel hydroxycarbonate and 2.7 g of citric acid into 20 g of deionized water, stir and evaporate on a heating table at 150 °C until it becomes semi-solid, cool to room temperature, add 15 g of ammonia water solution with a mass concentration of 15% and stir to dissolve to obtain a transparent solution, and then continue to add 8.6 g of (NH 4 ) 2 Mo 4 O 13 ·2H 2 O and stir to dissolve at room temperature. Then continue to add ammonia water solution with a mass concentration of 15% to make up the volume to 32 ml to prepare a nickel-molybdenum impregnation solution;

[0084] Impregnate the nickel-molybdenum impregnation solution on the carrier in step (2), dry at 110 °C for 2.5 h, and calcine at 550 °C for 2.5 h to obtain a catalyst product in the form of an oxide. The composition of this catalyst is: NiO, MoO 3 , MgO and Al 2 O 3 The contents are 0.9 wt%, 7.5 wt%, 4.0 wt% and 87.6 wt% in sequence.

[0085] Comparative Example 2 (compared with Example 4, without loading MgO)

[0086] Prepare a reverse water gas shift catalyst through the following steps:

[0087] (1) Weigh 91.6 g of TiO 2 -Al 2 O 3 pellet carrier, calcine at 600 °C for 6 h, and the specific surface area is 80.5 m 2 / g.

[0088] Then put the TiO 2 -Al 2 O 3 pellet carrier into a pressure bomb, add 150 g of urea aqueous solution with a mass concentration of 20%, put it into an oven at 200 °C and let it stand still for 24 h. After cooling, filter out the pellet carrier, dry it in an oven at 120 °C for 3 h, and then calcine it at 600 °C for 3 h. The specific surface area of the obtained carrier is 208.7 m 2 / g.

[0089] (2) Put 1.8 g of nickel hydroxycarbonate and 2.7 g of citric acid into 20 g of deionized water, stir and evaporate on a heating table at 150 °C until it becomes semi-solid, cool to room temperature, add 15 g of ammonia water solution with a mass concentration of 15% and stir to dissolve to obtain a transparent solution, and then continue to add 9.2 g of (NH 4 ) 6 Mo 7 O 24 .4H2 Dissolve it by stirring at room temperature, and continue to add an ammonia water solution with a mass concentration of 15% to make up to 32 ml to prepare a nickel-molybdenum impregnation solution;

[0090] Impregnate the nickel-molybdenum impregnation solution on the carrier obtained in step (1), dry it at 110 °C for 2.5 h, and calcine it at 550 °C for 2.5 h to obtain a catalyst product in the form of an oxide. The composition of this catalyst is: NiO, MoO 3 , TiO 2 and Al 2 O 3 The contents are 0.9 wt%, 7.5 wt%, 5.5 wt% and 86.1 wt% respectively in sequence.

[0091] Comparative Example 3 (compared with Example 4, without loading NiO)

[0092] Prepare a reverse water-gas shift catalyst through the following steps:

[0093] (1) Weigh 87.6 g of TiO 2 -Al 2 O 3 spherical carriers, calcine them at 600 °C for 6 h, and the specific surface area is 80.5 m 2 / g.

[0094] Then put the TiO 2 -Al 2 O 3 spherical carriers into a pressure bomb, add 150 g of a urea aqueous solution with a mass concentration of 20%, put it in an oven at 200 °C and let it stand still for 24 h. After cooling, filter out the spherical carriers, dry them in an oven at 120 °C for 3 h, and then calcine them at 600 °C for 3 h to obtain a carrier precursor, whose specific surface area is 208.7 m 2 / g.

[0095] (2) Dissolve 25.4 g of Mg(NO 3 ) 2 .6H 2 O in 18 g of deionized water to obtain a Mg salt solution.

[0096] Impregnate the Mg salt solution on the carrier precursor obtained in step (1), dry it at 120 °C for 2 h, and calcine it at 550 °C for 2.5 h to obtain a carrier loaded with MgO.

[0097] (3) Dissolve 10.3 g of (NH4) 6 Mo 7 O 24 .4H 2 O at room temperature in 20 g of an ammonia water solution with a mass concentration of 15% by stirring, and continue to add an ammonia water solution with a mass concentration of 15% to make up to 32 ml to prepare a molybdenum impregnation solution;

[0098] Impregnate the molybdenum impregnation solution on the carrier of step (2), dry it at 110 °C for 2.5 h, and calcine it at 550 °C for 2.5 h to obtain a catalyst product in the form of an oxide. The composition of this catalyst is: MoO 3 , MgO, TiO 2 and Al 2 O 3 The contents are 8.4 wt%, 4.0 wt%, 5.3 wt% and 82.3 wt% respectively in sequence.

[0099] Comparative Example 4 (compared with Example 4, the weight ratio of NiO / MoO 3 is greater than 0.15)

[0100] Prepare the reverse water gas shift catalyst through the following steps:

[0101] (1) Weigh 87.6 g of TiO 2 -Al 2 O 3 spherical carriers, calcine them at 600 °C for 6 h, and the specific surface area is 80.5 m 2 / g.

[0102] Then put the TiO 2 -Al 2 O 3 spherical carriers into a pressure bomb, load 150 g of an aqueous urea solution with a mass concentration of 20%, place it in an oven at 200 °C and let it stand still for 24 h. After cooling, filter out the spherical carriers, dry them in an oven at 120 °C for 3 h, and then calcine them at 600 °C for 3 h to obtain a carrier precursor, whose specific surface area is 208.7 m 2 / g.

[0103] (2) Dissolve 25.4 g of Mg(NO 3 ) 2 .6H 2 O in 18 g of deionized water to obtain a Mg salt solution.

[0104] Impregnate the Mg salt solution on the carrier precursor of step (1), dry it at 120 °C for 2 h, and calcine it at 550 °C for 2.5 h to obtain a carrier loaded with MgO.

[0105] (3) Put 3.9 g of nickel basic carbonate and 5.85 g of citric acid into 20 g of deionized water, stir and evaporate it on a heating table at 150 °C until it becomes semi-solid, cool it to room temperature, add 15 g of an ammonia water solution with a mass concentration of 15% and stir to dissolve to obtain a transparent solution. Then continue to add 7.9 g of (NH 4 ) 6 Mo 7 O 24 .4H 2Dissolve it by stirring at room temperature, and continue to add an ammonia water solution with a mass concentration of 15% to make up to 32 ml to prepare a nickel-molybdenum impregnation solution;

[0106] Impregnate the nickel-molybdenum impregnation solution on the carrier obtained in step (2), dry it at 110 °C for 2.5 h, and calcine it at 550 °C for 2.5 h to obtain a catalyst product in the form of an oxide. The composition of this catalyst is: NiO, MoO 3 , MgO, TiO 2 and Al 2 O 3 The contents are 2.0 wt%, 6.4 wt%, 4.0 wt%, 5.3 wt% and 82.3 wt% in sequence.

[0107] Comparative Example 5 (compared with Example 1, NiO / MoO 3 is 0.05)

[0108] Prepare a reverse water gas shift catalyst through the following steps:

[0109] (1) Weigh 84.5 g of TiO 2 -Al 2 O 3 spherical carriers, calcine them at 500 °C for 6 h, and the specific surface area is 98.5 m 2 / g.

[0110] Then put the TiO 2 -Al 2 O 3 spherical carriers into a pressure bomb, add 150 g of a urea aqueous solution with a mass concentration of 20%, place it in an oven at 180 °C and let it stand still for 24 h. After cooling, filter out the spherical carriers, dry them in an oven at 120 °C for 2 h, and then calcine them at 500 °C for 3 h to obtain a carrier precursor, whose specific surface area is 228.5 m 2 / g.

[0111] (2) Dissolve 31.8 g of Mg(NO 3 ) 2 ·6H 2 O in 15 g of deionized water to obtain a Mg salt solution.

[0112] Impregnate the Mg salt solution on the carrier precursor in step (1), dry it at 100 °C for 3 h, and calcine it at 500 °C for 3 h to obtain a carrier loaded with MgO.

[0113] (3) Put 0.98 g of basic nickel carbonate and 1.7 g of citric acid into 20 g of deionized water, stir and evaporate it on a heating table at 150 °C until it becomes semi-solid, cool it to room temperature, add 15 g of an ammonia water solution with a mass concentration of 15% and stir to dissolve to obtain a transparent solution, and continue to add 12.3 g of (NH 4 )6 Mo 7 O 24 ·4H 2 O is dissolved by stirring at room temperature, and an aqueous ammonia solution with a mass concentration of 15% is continuously added to make the volume up to 33 ml to prepare a nickel-molybdenum impregnation solution;

[0114] The nickel-molybdenum impregnation solution is impregnated on the carrier obtained in step (2), dried at 100 °C for 3 h, and calcined at 500 °C for 3 h to obtain a catalyst product in the form of an oxide. The composition of the catalyst is: NiO, MoO 3 , MgO, TiO 2 and Al 2 O 3 The contents are 0.5 wt%, 10.0 wt%, 5.0 wt%, 5.06 wt% and 79.44 wt% respectively.

[0115] Comparative Example 6 (compared with Example 2, NiO and MoO 3 are impregnated step by step)

[0116] The reverse water gas shift catalyst is prepared by the following steps:

[0117] (1) Weigh 91.5 g of TiO 2 -Al 2 O 3 spherical carriers, calcine them at 600 °C for 4 h, and the specific surface area is 81.2 m 2 / g.

[0118] Then put the TiO 2 -Al 2 O 3 spherical carriers into a pressure bomb, add 150 g of an aqueous ethylenediamine solution with a mass concentration of 20%, place it in an oven at 200 °C and let it stand still for 18 h. After cooling, filter out the spherical carriers, dry them in an oven at 100 °C for 3 h, and then calcine them at 600 °C for 2 h to obtain a carrier precursor, whose specific surface area is 249.5 m 2 / g.

[0119] (2) Dissolve 19.1 g of Mg(NO 3 ) 2 ·6H 2 O in 20 g of deionized water to obtain a Mg salt solution.

[0120] The Mg salt solution is impregnated on the carrier precursor obtained in step (1), dried at 110 °C for 2.5 h, and calcined at 600 °C for 2 h to obtain a carrier loaded with MgO.

[0121] (3) Dissolve 1.9 g of Ni(NO 3 ) 2 ·6H 2O is dissolved in 30 g of deionized water to obtain a Ni salt solution. The Ni salt solution is impregnated on the support obtained in step (2), dried at 120 °C for 2 h, and calcined at 600 °C for 2 h.

[0122] (4) Dissolve 6.1 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O in 27 g of deionized water to obtain a Mo salt solution. The Mo salt solution is impregnated on the support obtained in step (3), dried at 120 °C for 2 h, and calcined at 600 °C for 2 h to obtain a catalyst product in the form of an oxide. The composition of the catalyst is as follows: the contents of NiO, MoO 3 , MgO, TiO 2 and Al 2 O 3 are 0.5 wt%, 5.0 wt%, 3.0 wt%, 5.5 wt% and 86.0 wt% respectively.

[0123] Comparative Example 7 (compared with Example 1, the TiO 2 -Al 2 O 3 spheres were not treated at high temperature in an aqueous urea solution)

[0124] (1) Weigh 83.5 g of TiO 2 -Al 2 O 3 spheres support, calcine at 500 °C for 6 h, and the specific surface area is 98.5 m 2 / g.

[0125] (2) Dissolve 31.8 g of Mg(NO 3 ) 2 ·6H 2 O in 15 g of deionized water to obtain a Mg salt solution.

[0126] The Mg salt solution is impregnated on the support precursor in step (1), dried at 100 °C for 3 h, and calcined at 500 °C for 3 h to obtain a support loaded with MgO.

[0127] (3) Put 2.9 g of nickel basic carbonate and 4.4 g of citric acid into 20 g of deionized water, stir and evaporate on a heating table at 150 °C until it becomes semi-solid, cool to room temperature, add 15 g of ammonia water with a mass concentration of 15% and stir to dissolve to obtain a transparent solution, and then continue to add 12.3 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2Dissolve it by stirring at room temperature, and continue to add an ammonia water solution with a mass concentration of 15% to make up to 33 ml to prepare a nickel-molybdenum impregnation solution;

[0128] Impregnate the nickel-molybdenum impregnation solution on the carrier obtained in step (2), dry it at 100 °C for 3 h, and calcine it at 500 °C for 3 h to obtain a catalyst product in the form of an oxide. The composition of this catalyst is: NiO, MoO 3 , MgO, TiO 2 and Al 2 O 3 The contents of are 1.5 wt%, 10.0 wt%, 5.0 wt%, 5.0 wt% and 78.5 wt% in sequence.

[0129] Test Example 1

[0130] The catalysts prepared in the above respective examples and comparative examples were evaluated according to the following method: It was carried out on a micro-reaction evaluation device, and the catalyst filling amount was 1.0 g. The catalyst was first reduced, and the reduction conditions were: the temperature was 400 °C, the composition (v / v) of the reduction atmosphere was 20% H 2 and 80% N 2 , the pressure was 0.1 MPa, the volume space velocity was 5000 h -1 , and the reduction time was 3 h. After the reduction was completed, the catalyst was contacted with the raw material gas for catalyst evaluation. The contact conditions were: the temperature was 400 °C, the pressure was 2 MPa, the volume space velocity was 10000 h -1 , and the composition (v / v) of the raw material gas was CO 2 / H 2 / N 2 = 30% / 60% / 10%, and the running time was 24 h.

[0131] Test Example 2

[0132] The catalysts prepared in the above respective examples and comparative examples were subjected to a catalyst accelerated deactivation experiment in the following manner: In the accelerated deactivation experiment, the catalyst was first at 400 °C, 2 MPa and a volume space velocity of 10000 h -1 under contact with the raw material gas (the composition (v / v) of the raw material gas was CO 2 / H 2 / N 2 = 30% / 60% / 10%) for evaluation. The running time of this stage was 24 h, and the CO 2 conversion rate was recorded as After that, the temperature was raised to 800 °C and run for 8 h; then it was lowered to 400 °C and continued to run for 24 h. The CO 2 conversion rate of this stage was recorded as Calculate the activity retention rate r of the catalyst. The calculation formula is

[0133] The experimental results of the catalysts of various embodiments and comparative examples in Test Example 1 and Test Example 2 are shown in Table 1.

[0134] Table 1

[0135]

[0136] The catalysts obtained by using the embodiments 1-4 of the present invention are 2 and H 2 The catalytic performance of preparing CO by reverse water gas shift reaction is better than that of the comparative example. 2 Close to the thermodynamic equilibrium conversion rate, CH 4 The selectivity is below 0.5%, and the accelerated deactivation experiment shows that the activity retention rate is not less than 90%, indicating that the provided catalyst can take into account very high activity, anti-methanation performance and high-temperature anti-hydration stability.

[0137] Comparative Example 1 The catalyst carrier is activated alumina beads without TiO 2 From the evaluation results, it can be seen that the catalyst activity and stability are comparable to those of Examples 1-4, but CH 4 The selectivity is obviously higher, which proves that the 2 The alumina pellets as carrier raw materials have a significant effect on controlling the methanogenic side reaction. The catalyst of Comparative Example 2 does not contain MgO. Compared with the embodiment, the catalyst of Comparative Example 2 has a poor activity retention rate after high temperature reaction. The catalyst of Comparative Example 3 does not contain Ni, which has a great impact on the activity, which is significantly lower than the catalyst containing NiMo. The Ni content in the catalyst of Comparative Example 4 is too high, and NiO and MoO 3 The weight ratio of NiO and MoO is not within the range of 0.1-0.15, and the obtained catalyst has a significantly increased methanogenic side reaction. 3 The weight ratio of NiO and MoO in the catalyst of Comparative Example 6 is lower than 0.1, and the activity of the obtained catalyst is significantly reduced. 3 The catalyst was impregnated in steps, and the uniform loading of the two was not achieved. The activity and anti-methanation performance of the obtained catalyst were poor. 2 -Al 2 O 3 The carrier has not been subjected to high-temperature hydrothermal treatment with an alkaline solution, and has a low specific surface area. The activity and anti-methanation performance of the prepared catalyst are lower than those of the embodiment.

[0138] It is easy to understand that the above embodiments are merely examples for clear illustration, and do not mean that the present invention is only limited thereto. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A preparation method of a reverse water gas shift catalyst, characterized in that, it comprises the following steps: (1) Doped with TiO 2 Al 2 O 3 The substrate is first calcined, then placed in an alkaline solution for heating at 180-200° C., and then dried and second calcined to obtain a carrier precursor; (2) Impregnate the carrier precursor obtained in step (1) with a Mg salt solution, and after drying, perform a third calcination to obtain a carrier loaded with MgO; (3) Impregnate the carrier obtained in step (2) with an impregnation solution containing Ni and Mo, and after drying, perform a fourth calcination to obtain a reverse water gas shift catalyst loaded with NiO and MoO 3 ; Among them, in the reverse water gas shift catalyst, it contains the following components in weight percentages: NiO 0.5 - 1.5%, MoO 3 5.0 - 10.0%, MgO 3.0 - 5.0%, TiO 2 5.0 - 5.5%, Al 2 O 3 78.5 - 86.0%, and the weight ratio of the NiO to the MoO 3 is 0.1 - 0.

15.

2. The preparation method according to claim 1, characterized in that, in step (1), the alkaline solution is an aqueous urea solution or an aqueous ethylenediamine solution; preferably, the mass concentration of the alkaline solution is 15-25%; preferably, in step (1), the time of the heat treatment is 18-24 h; preferably, in step (1), the temperature of the first calcination is 500-600 °C, and the calcination time is preferably 4-6 h; preferably, in step (1), the temperature of the second calcination is 500-600 °C, and the calcination time is preferably 2-3 h.

3. The preparation method according to claim 1 or 2, characterized in that, in step (2), the temperature of the third calcination is 500-600 °C, and the calcination time is preferably 2-3 h; And / or, in step (2), the Mg salt in the Mg salt solution is Mg(NO 3 ) 2 ·6H 2 O and / or Mg(CH 3 COO) 2 ·4H 2 O; and / or, in step (2), the impregnation is carried out by the incipient wetness impregnation method.

4. The preparation method according to any one of claims 1-3, characterized in that, in step (3), the preparation steps of the impregnation solution containing Ni and Mo include: Mix nickel basic carbonate and citric acid evenly in water, then heat to evaporate the water, preferably heat to evaporate until it becomes paste-like or semi-solid; after cooling, add ammonia water to dissolve to obtain a transparent solution, and then add ammonium molybdate to the transparent solution and stir to dissolve to obtain the impregnation solution containing Ni and Mo; preferably, the dosage of the citric acid is 1.25-1.75 times the weight of the nickel basic carbonate; Preferably, the ammonium molybdate is selected from (NH 4 ) 6 Mo 7 O 24 ·4H 2 O and / or (NH 4 ) 2 Mo 4 O 13 ·2H 2 O.

5. The preparation method according to any one of claims 1-4, characterized in that, in step (3), the temperature of the fourth calcination is 500-600 °C, and the calcination time is preferably 2-3 h; and / or, in step (3), the impregnation is carried out by the incipient wetness impregnation method.

6. The preparation method according to any one of claims 1-5, characterized in that, The Al 2 O 3 substrate is an Al 2 O 2 sphere doped with TiO 3 with a preferred particle size of 3-5 mm.

7. A reverse water gas shift catalyst, characterized in that, based on the total weight of the catalyst, the catalyst contains the following components in weight percentages: NiO 0.5 - 1.5%, MoO 3 5.0 - 10.0%, MgO 3.0 - 5.0%, TiO 2 5.0 - 5.5%, Al 2 O 3 78.5 - 86.0%, and the weight ratio of the NiO and the MoO 3 is 0.1 - 0.15; preferably, the catalyst is prepared by the preparation method according to any one of claims 1-6.

8. A reverse water gas shift catalyst, characterized in that, The catalyst includes a carrier and NiO and MoO supported on the carrier. 3 , the carrier includes a carrier precursor and MgO supported on the carrier precursor, and the carrier precursor is an Al 2 O 2 matrix doped with TiO 3 ; Based on the total weight of the catalyst, the content of NiO is 0.5 - 1.5%, the content of MoO 3 is 5.0 - 10.0%, the content of MgO is 3.0 - 5.0%, the content of TiO 2 is 5.0 - 5.5%, the content of Al 2 O 3 is 78.5 - 86.0%, and the weight ratio of NiO and MoO 3 is 0.1 - 0.15; preferably, the catalyst is prepared by the preparation method according to any one of claims 1-6.

9. An application, characterized in that, The catalyst prepared by the preparation method according to any one of claims 1-6 or the catalyst according to any one of claims 7-8 is used in the process of catalytically preparing CO 2 and H 2 by the reverse water gas shift reaction to prepare CO 10. The application according to claim 9, characterized in that, the catalyst is reduced before use; preferably, the conditions for the reduction include: the temperature is 350-400 °C, the reduction atmosphere is a mixed gas of hydrogen and nitrogen, preferably the volume percentages of hydrogen and nitrogen are 10-20% and 80-90% respectively, and the reaction pressure is 0.1-1.0 MPa.

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