A carbon dioxide hydrogenation catalyst and its preparation method and application

Abstract

The invention discloses a carbon dioxide hydrogenation catalyst, a preparation method and an application thereof. The catalyst comprises 10-80 wt% of a nano-metal oxide and 20-90 wt% of a modified ZSM-5 molecular sieve, and is obtained by treating the nano-metal oxide and the modified ZSM-5 molecular sieve with a silane coupling agent and then calcining the catalyst. The nano-metal oxide comprises a component A and a component B, wherein the component A is selected from any three of iron oxide, cobalt oxide, molybdenum oxide, nickel oxide and copper oxide, and the component B is selected from any one of zirconium oxide, potassium oxide and calcium oxide. The modified ZSM-5 molecular sieve comprises a component A, a component B and a ZSM-5 molecular sieve, wherein the component A is selected from any one of lanthanum oxide and cerium oxide, and the component B is selected from any one of potassium oxide and magnesium oxide. The catalyst has high catalytic activity and strong anti-deactivation ability, and can convert carbon dioxide into chemicals such as ethylene and propylene in a one-step process.

Description

Technical Field

[0001] The present invention relates to the field of catalysts, and in particular to a carbon dioxide hydrogenation catalyst, a preparation method and an application thereof. Background Art

[0002] Carbon dioxide is considered the most significant greenhouse gas, and major economies around the world are facing severe pressure to reduce emissions. Furthermore, carbon dioxide is a naturally occurring, abundant "carbon source" compound. If we can leverage advanced scientific and technological means to "turn waste into treasure," we can not only effectively mitigate the environmental impacts of carbon dioxide emissions but also provide an ideal energy source. The resourceful utilization of carbon dioxide is an effective way to address the greenhouse effect, replace fossil fuels, and generate higher economic value. It is of great significance to the sustainable development of my country's energy and environment.

[0003] Using hydrogen produced from clean energy to directly convert CO2 into high-value-added bulk chemicals such as aromatics and liquid fuels is an important pathway for CO2 resource utilization. While significant progress has been made in the reduction of CO2 to produce small C1 molecules such as methanol, formic acid, and methane, direct CO2 hydrogenation to chemicals with two or more carbon atoms remains a significant challenge.

[0004] Currently, CO2 hydrogenation to produce light olefins, aromatics, and liquid fuels primarily occurs via two reaction pathways. The first is the methanol intermediate pathway, which uses zinc-, zirconium-, chromium-, or indium-based catalysts to convert CO2 hydrogenation to produce methanol and other intermediates. These intermediates are then converted to high-value-added chemicals such as light olefins, aromatics, and liquid fuels over molecular sieve catalysts (such as H-ZSM-5 and SAPO-34). This pathway, currently the predominant method for producing high-value-added chemicals from CO2 hydrogenation, boasts high selectivity for the target product over hydrocarbons. However, a limitation is that the reaction conditions for CO2 hydrogenation to methanol are mismatched with those for methanol conversion, resulting in low CO2 conversion and high selectivity for the byproduct CO (over 50%). The second is the light olefin intermediate pathway, which uses a reaction process and catalyst design modeled after the FTS reaction. Specifically, CO2 is converted to light hydrocarbons over an iron-based catalyst via the RWGS and FTS processes. This is then converted to high-value-added chemicals such as aromatics and liquid fuels over a molecular sieve catalyst. While this pathway offers high CO2 conversion but low CO selectivity, its main drawback is the high content of light alkanes in the final product, resulting in low yields of the target product. As can be seen, both of the aforementioned pathways suffer from low yields of the target products. Furthermore, the resulting target products are complex in composition, making separation difficult. The significant separation energy consumption inevitably leads to high separation costs, making CO2 hydrogenation to light olefins, aromatics, and liquid fuels uneconomical. Therefore, the rational design and preparation of bifunctional "metal-molecular sieve" catalysts is crucial for improving CO2 conversion and target product yields.

[0005] Chinese patent document 201410498074.2 provides a catalyst for producing methanol by hydrogenating carbon dioxide, a method for preparing the catalyst, and a method for synthesizing methanol. The catalyst comprises the following components, calculated by weight: 85 to 99 parts of a carrier; 1 to 15 parts of at least one active element selected from Pd, Pt, or Cu. This method first produces methanol by hydrogenating carbon dioxide, and then produces chemicals from methanol. The preparation process is complex, and the investment and energy consumption are high.

[0006] Chinese patent document CN106423263A provides a catalyst for directly preparing light olefins by hydrogenating carbon dioxide, a method for preparing the catalyst, and a method for synthesizing light olefins. The catalyst comprises the following components, measured by mass: M is a metal oxide complex, accounting for 20 to 70%; Z is a molecular sieve (one of SAPO-34, HSM-5, and HY molecular sieves), accounting for 30 to 80%; the CO2 conversion rate can reach about 10%, and the selectivity for light olefins in the hydrogenation product is 80%; however, the selectivity for light olefins in this process is still low, and a large amount of methane and other long-chain alkanes are generated, resulting in low hydrogen utilization. Summary of the Invention

[0007] In order to address the deficiencies in the prior art, the present invention aims to provide a carbon dioxide hydrogenation catalyst, a preparation method, and an application thereof. The catalyst has the characteristics of high catalytic activity, good stability, excellent selectivity, and strong resistance to deactivation, and can convert carbon dioxide into high-value-added chemicals such as ethylene and propylene in a one-step process.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A carbon dioxide hydrogenation catalyst comprises 10-80 wt% of nano metal oxide and 20-90 wt% of modified ZSM-5 molecular sieve. The nano metal oxide and modified ZSM-5 molecular sieve are treated with a silane coupling agent and then calcined to obtain the carbon dioxide hydrogenation catalyst.

[0010] Preferably, the carbon dioxide hydrogenation catalyst comprises 20-50 wt% of nano metal oxide and 50-80 wt% of modified ZSM-5 molecular sieve. The nano metal oxide and modified ZSM-5 molecular sieve are treated with a silane coupling agent and then calcined to obtain the carbon dioxide hydrogenation catalyst.

[0011] Preferably, the nano metal oxide comprises component A and component B, component A is selected from any three of iron oxide, cobalt oxide, molybdenum oxide, nickel oxide, and copper oxide, and component B is selected from any one of zirconium oxide, potassium oxide, and calcium oxide.

[0012] Preferably, component A includes component 1, component 2, and component 3, wherein component 1, component 2, and component 3 are any three selected from iron oxide, cobalt oxide, molybdenum oxide, nickel oxide, and copper oxide, and their weight percentage of the nano metal oxide is 1 to 80%.

[0013] Preferably, component A includes component 1, component 2, and component 3, wherein component 1, component 2, and component 3 are any three selected from iron oxide, cobalt oxide, molybdenum oxide, nickel oxide, and copper oxide, and their weight percentage of the nano metal oxide is 10-70%.

[0014] Preferably, the weight percentage of component B in the nano-metal oxide is 1-10%.

[0015] Preferably, the weight percentage of component B in the nano-metal oxide is 1-5%.

[0016] Preferably, the modified ZSM-5 molecular sieve comprises component a, component b and ZSM-5 molecular sieve, component a is selected from any one of lanthanum oxide and cerium oxide, and component b is selected from any one of potassium oxide and magnesium oxide.

[0017] Preferably, the weight percentage of component a in the modified ZSM-5 molecular sieve is 0.1-5%, and the weight percentage of component b in the modified ZSM-5 molecular sieve is 0.1-3%.

[0018] Preferably, the weight percentage of component a in the modified ZSM-5 molecular sieve is 0.5-3%, and the weight percentage of component b in the modified ZSM-5 molecular sieve is 0.1-1.5%.

[0019] Preferably, the silane coupling agent is KH560 and / or KH570.

[0020] The present invention also claims a method for preparing the catalyst, comprising the following steps:

[0021] (1) dissolving a first metal salt in deionized water, then adding sucrose and polyethylene glycol, stirring to obtain a sol, and drying and calcining the sol to obtain a nano-metal oxide;

[0022] (2) dissolving a second metal salt in deionized water to obtain a second metal salt solution, aging the ZSM-5 molecular sieve, then impregnating the ZSM-5 molecular sieve with the second metal salt solution, allowing the mixture to stand, drying, and calcining to obtain a modified ZSM-5 molecular sieve;

[0023] (3) The nano-metal oxide and the modified ZSM-5 molecular sieve are dispersed in deionized water, ethanol and a silane coupling agent are added, and the mixture is stirred thoroughly to obtain a slurry. The slurry is spray-dried to form a slurry, and then dried and calcined to obtain a carbon dioxide hydrogenation catalyst.

[0024] Preferably, in step (1), the first metal salt is one or more nitrates of Fe, Co, Mo, Ni, Cu, Zr, K, and Ca, and the weight ratio of the first metal salt to deionized water is 15 to 40:100; in step (2), the second metal salt is one or more nitrates of La, Ce, K, and Mg, and the weight ratio of the second metal salt to deionized water is 10 to 30:100.

[0025] Preferably, in step (1), the stirring conditions are stirring at 40-95° C. for 5-15 hours, the drying conditions are drying at 110-120° C. for 10-15 hours, and the calcination conditions are calcining at 400-600° C. for 5-15 hours.

[0026] Preferably, in step (1), the polyethylene glycol is PEG2000 and / or PEG4000; sucrose and polyethylene glycol account for 0.01-5% and 0.01-10% of the weight of the sol, respectively.

[0027] Preferably, in step (1), sucrose and polyethylene glycol account for 0.1-3% and 0.1-5% of the weight of the sol, respectively.

[0028] Preferably, in step (2), the aging conditions are aging at 550-700°C for 2-5h, standing time is 10-15h, drying conditions are drying at 100-120°C for 8-15h, and calcination conditions are calcination at 500-600°C for 10-15h; the ZSM-5 molecular sieve particle size is <800nm, and the silicon-aluminum ratio is 80-300.

[0029] Preferably, in step (2), the particle size of the ZSM-5 molecular sieve is less than 800 nm, and the silicon-aluminum ratio is 100-200.

[0030] Preferably, in step (3), ethanol and silane coupling agent account for 0.5-3% and 1-5% of the weight of the slurry, respectively.

[0031] Preferably, in step (3), the solid content of the slurry is 25 to 35 wt%.

[0032] Preferably, in step (3), the furnace temperature during spray drying is 300-450°C, the drying tower outlet temperature is 130-250°C, and the drying tower spray pressure is 2.0-4.0 MPa; the catalyst particle size after spray drying is 15-35 μm; after the catalyst is formed, the drying conditions are drying at 100-130°C for 4-7 hours, and the calcination conditions are calcining at 400-600°C for 5-10 hours.

[0033] The present invention also claims a use of the catalyst in carbon dioxide hydrogenation reaction.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1) The carbon dioxide hydrogenation catalyst provided by the present invention can directly hydrogenate carbon dioxide to produce chemicals such as ethylene, propylene, and butene;

[0036] 2) The carbon dioxide hydrogenation catalyst provided by the present invention has a nano-scale hydrogenation metal oxide, which can effectively improve the hydrogenation activity and increase the conversion rate of carbon dioxide hydrogenation;

[0037] 3) The carbon dioxide hydrogenation catalyst provided by the present invention, ZSM-5 molecular sieve, after treatment and modification, has good hydrothermal stability and coke holding capacity, so that the catalyst has good selectivity and life;

[0038] 4) The carbon dioxide hydrogenation catalyst provided by the present invention, in which the nano-metal oxide and the modified ZSM-5 molecular sieve are modified with a silane coupling agent, has a tighter connection and higher catalytic efficiency than simple mechanical mixing or binder mixing, can effectively reduce the formation of by-products, and improve the conversion rate and target product selectivity;

[0039] 5) The carbon dioxide hydrogenation catalyst provided by the present invention has cheap and readily available raw materials, a simple preparation process, and low production cost. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. Of course, the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0041] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased from commercial sources or synthesized from commercially purchased raw materials.

[0042] The present invention discloses a carbon dioxide hydrogenation catalyst, comprising 10-80 wt% of a nano metal oxide and 20-90 wt% of a modified ZSM-5 molecular sieve. The nano metal oxide and the modified ZSM-5 molecular sieve are treated with a silane coupling agent and then calcined to obtain the carbon dioxide hydrogenation catalyst.

[0043] The nano-metal oxide may account for 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt% of the nano-metal oxide, preferably 20 to 50 wt%;

[0044] The modified ZSM-5 molecular sieve may account for 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt% of the nano metal oxide, preferably 50 to 80 wt%.

[0045] Specifically, the nano metal oxide includes component A and component B, component A is selected from any three of iron oxide, cobalt oxide, molybdenum oxide, nickel oxide, and copper oxide, and component B is selected from any one of zirconium oxide, potassium oxide, and calcium oxide.

[0046] More specifically, component A includes component 1, component 2, and component 3, wherein component 1, component 2, and component 3 are any three selected from iron oxide, cobalt oxide, molybdenum oxide, nickel oxide, and copper oxide, and their weight percentage of the nano-metal oxide is 1 to 80%, which can be 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%, and more preferably, 10 to 70%;

[0047] More specifically, the weight percentage of component B in the nano-metal oxide is 1-10%, which can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, and more preferably, 1-5%.

[0048] Specifically, the modified ZSM-5 molecular sieve includes component a, component b and ZSM-5 molecular sieve, component a is selected from any one of lanthanum oxide and cerium oxide, and component b is selected from any one of potassium oxide and magnesium oxide.

[0049] More specifically, the weight percentage of component a in the modified ZSM-5 molecular sieve is 0.1-5%, which can be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, and more preferably, 0.5-3%;

[0050] More specifically, the weight percentage of component b in the modified ZSM-5 molecular sieve is 0.1-3%, which may be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, and more preferably 0.1-1.5%.

[0051] Preferably, the silane coupling agent is KH560 and / or KH570.

[0052] The present invention also provides a method for preparing the catalyst, comprising the following steps:

[0053] (1) dissolving a first metal salt in deionized water, then adding sucrose and polyethylene glycol, stirring to obtain a sol, and drying and calcining the sol to obtain a nano-metal oxide;

[0054] Specifically, in step (1), the first metal salt is one or more nitrates of Fe, Co, Mo, Ni, Cu, Zr, K, and Ca, and the weight ratio of the first metal salt to deionized water is 15 to 40:100, and can be 15:100, 20:100, 25:100, 30:100, 35:100, or 40:100.

[0055] Specifically, in step (1), the stirring conditions are stirring at 40-95° C. for 5-15 hours, the drying conditions are drying at 110-120° C. for 10-15 hours, and the calcination conditions are calcining at 400-600° C. for 5-15 hours.

[0056] Specifically, in step (1), the polyethylene glycol is PEG2000 and / or PEG4000;

[0057] Optionally, in step (1), sucrose is 0.01-5% by weight of the sol, which can be 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, preferably 0.1-3%;

[0058] Optionally, in step (1), the polyethylene glycol is 0.01-10% by weight of the sol, which can be 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, preferably 0.1-5%;

[0059] (2) dissolving a second metal salt in deionized water to obtain a second metal salt solution, aging the ZSM-5 molecular sieve, then impregnating the ZSM-5 molecular sieve with the second metal salt solution, allowing the mixture to stand, drying, and calcining to obtain a modified ZSM-5 molecular sieve;

[0060] Specifically, in step (2), the second metal salt is one or more nitrates of La, Ce, K, and Mg, and the weight ratio of the second metal salt to deionized water is 10 to 30:100, and can be 10:100, 15:100, 20:100, 25:100, or 30:100.

[0061] Specifically, in step (2), the aging conditions are aging at 550-700°C for 2-5 hours, the standing time is 10-15 hours, the drying conditions are drying at 100-120°C for 8-15 hours, and the calcination conditions are calcining at 500-600°C for 10-15 hours;

[0062] Specifically, in step (2), the particle size of the ZSM-5 molecular sieve is less than 800 nm, and the silicon-aluminum ratio is 80-300, which can be 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, preferably 100-200.

[0063] (3) The nano-metal oxide and the modified ZSM-5 molecular sieve are dispersed in deionized water, ethanol and a silane coupling agent are added, and the mixture is stirred thoroughly to obtain a slurry. The slurry is spray-dried to form a slurry, and then dried and calcined to obtain a carbon dioxide hydrogenation catalyst.

[0064] Specifically, in step (3), ethanol accounts for 0.5-3% of the weight of the slurry, which can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, or 3%.

[0065] Specifically, in step (3), the silane coupling agent accounts for 1-5% of the weight of the slurry, which can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%.

[0066] More specifically, in step (3), the solid content of the slurry is 25-35wt%, which can be 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt%, 31wt%, 32wt%, 33wt%, 34wt%, or 35wt%.

[0067] Specifically, in step (3), during spray drying, the furnace temperature is 300-450°C, the drying tower outlet temperature is 130-250°C, and the drying tower spray pressure is 2.0-4.0 MPa; the catalyst particle size after spray drying is 15-35 μm; after the catalyst is formed, the drying conditions are 100-130°C for 4-7 hours, and the calcination conditions are 400-600°C for 5-10 hours.

[0068] The present invention also claims a use of the catalyst in carbon dioxide hydrogenation reaction.

[0069] The present invention will be further described below with reference to specific examples.

[0070] Example 1

[0071] A method for preparing a carbon dioxide hydrogenation catalyst comprises the following steps:

[0072] (1) 5 kg Fe(NO3)3·9H2O, 0.2 kg Cu(NO3)2·3H2O, 3.2 kg Ni(NO3)2·6H2O, and 0.04 kg Zr(NO3)4·5H2O were dissolved in 20 kg deionized water, stirred evenly, and then 0.05 kg sucrose and 0.2 kg PEG2000 were added. The mixture was stirred at 80°C for 8 h to obtain a sol. The sol was dried at 120°C for 10 h and then calcined at 480°C for 8 h to obtain nano-metal oxides.

[0073] (2) 92 g of La(NO3)3·6H2O and 4 g of KNO3 were dissolved in 500 g of deionized water to obtain a modified solution. 1 kg of nano ZSM-5 molecular sieve was aged at 550°C for 2 h, and then the ZSM-5 molecular sieve was impregnated with the modified solution, allowed to stand for 12 h, dried at 110°C for 8 h, and then calcined at 550°C for 12 h to obtain a modified ZSM-5 molecular sieve.

[0074] (3) The nano-metal oxide obtained in step (1) and the modified ZSM-5 molecular sieve obtained in step (2) are dispersed in 7 kg of deionized water, and then 100 g of ethanol and 300 g of silane coupling agent KH560 are added and stirred thoroughly to obtain a slurry. The slurry is sent to a spray drying tower and spray-dried to obtain a molded catalyst under the conditions of a furnace temperature of 400° C., an outlet temperature of 150° C., and a spray pressure of 3.0 MPa. The molded catalyst is then dried at 130° C. for 7 h and then calcined at 500° C. for 10 h to obtain a carbon dioxide hydrogenation catalyst.

[0075] Example 2

[0076] A method for preparing a carbon dioxide hydrogenation catalyst comprises the following steps:

[0077] (1) 6.2 kg Fe(NO3)3·9H2O, 0.3 kg Cu(NO3)2·3H2O, 2 kg Ni(NO3)2·6H2O, and 0.07 kg Zr(NO3)4·5H2O were dissolved in 20 kg deionized water, stirred evenly, and then 0.08 kg sucrose and 0.3 kg PEG2000 were added. The mixture was stirred at 75°C for 10 h to obtain a sol. The sol was dried at 120°C for 10 h and then calcined at 480°C for 8 h to obtain nano-metal oxides.

[0078] (2) 120 g of La(NO3)3·6H2O and 2 g of KNO3 were dissolved in 500 g of deionized water to obtain a modified solution. 1 kg of nano ZSM-5 molecular sieve was aged at 550°C for 3 h, and then the ZSM-5 molecular sieve was impregnated with the modified solution, allowed to stand for 12 h, dried at 110°C for 8 h, and then calcined at 550°C for 12 h to obtain a modified ZSM-5 molecular sieve.

[0079] (3) The nano-metal oxide obtained in step (1) and the modified ZSM-5 molecular sieve obtained in step (2) are dispersed in 6.5 kg of deionized water, and then 90 g of ethanol and 200 g of silane coupling agent KH570 are added and stirred thoroughly to obtain a slurry. The slurry is sent to a spray drying tower and spray-dried to obtain a molded catalyst under the conditions of a furnace temperature of 400° C., an outlet temperature of 150° C., and a spray pressure of 3.0 MPa. The molded catalyst is then dried at 130° C. for 7 h and then calcined at 500° C. for 10 h to obtain a carbon dioxide hydrogenation catalyst.

[0080] Example 3

[0081] A method for preparing a carbon dioxide hydrogenation catalyst comprises the following steps:

[0082] (1) 4.1 kg Fe(NO3)3·9H2O, 0.2 kg Cu(NO3)2·3H2O, 3.6 kg Ni(NO3)2·6H2O, and 0.05 kg Zr(NO3)4·5H2O were dissolved in 20 kg deionized water, stirred evenly, and then 0.1 kg sucrose and 0.4 kg PEG4000 were added. The mixture was stirred at 80°C for 10 h to obtain a sol, which was dried at 120°C for 10 h and then calcined at 480°C for 8 h to obtain nano-metal oxides.

[0083] (2) 187 g of La(NO3)3·6H2O and 10 g of KNO3 were dissolved in 500 g of deionized water to obtain a modified solution. 1 kg of nano ZSM-5 molecular sieve was aged at 600°C for 2 h, and then the ZSM-5 molecular sieve was impregnated with the modified solution, allowed to stand for 12 h, dried at 110°C for 8 h, and then calcined at 550°C for 12 h to obtain a modified ZSM-5 molecular sieve.

[0084] (3) The nano-metal oxide obtained in step (1) and the modified ZSM-5 molecular sieve obtained in step (2) were dispersed in 6 kg of deionized water, and then 150 g of ethanol and 100 g of KH560 and 180 g of KH570 were added and stirred thoroughly to obtain a slurry. The slurry was sent to a spray drying tower and spray-dried to obtain a molded catalyst under the conditions of a furnace temperature of 400° C., an outlet temperature of 150° C., and a spray pressure of 4.0 MPa. The molded catalyst was then dried at 130° C. for 7 h and then calcined at 500° C. for 10 h to obtain a carbon dioxide hydrogenation catalyst.

[0085] Example 4

[0086] A method for preparing a carbon dioxide hydrogenation catalyst comprises the following steps:

[0087] (1) 2.6 kg Co(NO3)2·6H2O, 0.1 kg Cu(NO3)2·3H2O, 1 kg (NH4)2MoO4, and 0.01 kg KNO3 were dissolved in 20 kg deionized water, stirred evenly, and then 0.1 kg sucrose and 0.3 kg PEG4000 were added. The mixture was stirred at 80°C for 10 h to obtain a sol. The sol was dried at 120°C for 10 h and then calcined at 480°C for 8 h to obtain nano-metal oxides.

[0088] (2) 50 g of La(NO3)3·6H2O and 32 g of Mg(NO3)2·6H2O were dissolved in 550 g of deionized water to obtain a modified solution. 1 kg of nano ZSM-5 molecular sieve was aged at 600°C for 2 h, and then the ZSM-5 molecular sieve was impregnated with the modified solution, allowed to stand for 12 h, dried at 110°C for 8 h, and then calcined at 550°C for 12 h to obtain a modified ZSM-5 molecular sieve.

[0089] (3) The nano-metal oxide obtained in step (1) and the modified ZSM-5 molecular sieve obtained in step (2) were dispersed in 7.5 kg of deionized water, and then 80 g of ethanol and 250 g of KH570 were added and stirred thoroughly to obtain a slurry. The slurry was sent to a spray drying tower and spray-dried to obtain a molded catalyst under the conditions of a furnace temperature of 400° C., an outlet temperature of 150° C., and a spray pressure of 4.0 MPa. The molded catalyst was then dried at 130° C. for 7 h and then calcined at 500° C. for 10 h to obtain a carbon dioxide hydrogenation catalyst.

[0090] Example 5

[0091] A method for preparing a carbon dioxide hydrogenation catalyst comprises the following steps:

[0092] (1) 3.4 kg Fe(NO3)3·9H2O, 5.5 kg Co(NO3)2·6H2O, 2 kg Ni(NO3)2·6H2O, and 0.02 kg Ca(NO3)2 were dissolved in 20 kg deionized water, stirred evenly, and then 0.4 kg sucrose and 0.5 kg PEG2000 were added. The mixture was stirred at 80°C for 10 h to obtain a sol, which was dried at 120°C for 10 h and then calcined at 480°C for 8 h to obtain nano-metal oxides.

[0093] (2) 60 g of La(NO3)3·6H2O and 40 g of Mg(NO3)2·6H2O were dissolved in 550 g of deionized water to obtain a modified solution. 1 kg of nano ZSM-5 molecular sieve was aged at 600°C for 2 h, and then the ZSM-5 molecular sieve was impregnated with the modified solution, allowed to stand for 12 h, dried at 110°C for 8 h, and then calcined at 550°C for 12 h to obtain a modified ZSM-5 molecular sieve.

[0094] (3) The nano-metal oxide obtained in step (1) and the modified ZSM-5 molecular sieve obtained in step (2) were dispersed in 6.5 kg of deionized water, and then 180 g of ethanol and 230 g of KH570 were added and stirred thoroughly to obtain a slurry. The slurry was sent to a spray drying tower and spray-dried to obtain a molded catalyst under the conditions of a furnace temperature of 400° C., an outlet temperature of 150° C., and a spray pressure of 4.0 MPa. The molded catalyst was then dried at 130° C. for 7 h and then calcined at 500° C. for 10 h to obtain a carbon dioxide hydrogenation catalyst.

[0095] Table 1 below shows the physical properties of the carbon dioxide hydrogenation catalysts prepared in Examples 1 to 5.

[0096] Table 1 Physical properties of the carbon dioxide hydrogenation catalysts prepared in Examples 1 to 5

[0097] Catalyst properties Catalyst 1 Catalyst 2 Catalyst 3 Catalyst 4 Catalyst 5 <![CDATA[Specific surface area / (m 2 / g)]]> 333 317 324 310 305 Pore ​​volume / (mL / g) 0.19 0.19 0.19 0.18 0.18

[0098] Test results for the hydrogenation of carbon dioxide to olefins using the catalysts prepared in Examples 1-5 of the present invention. The tests were conducted in a microchannel reactor apparatus, using carbon dioxide and hydrogen in a volume ratio of 1:4. The reaction temperature was 400°C and the pressure was 3 MPa. The test results are shown in Table 2.

[0099] Table 2 Experimental results of carbon dioxide hydrogenation of catalysts prepared in Examples 1 to 5

[0100] Catalyst 1 Catalyst 2 Catalyst 3 Catalyst 4 Catalyst 5 <![CDATA[CO2 conversion rate / %]]> 41.9 40.3 41.5 38.5 37.7 <![CDATA[C1+C2 0 / wt%]]> 14.4 12.8 15.1 20.5 19.7 <![CDATA[C2 ＝ +C3 ＝ / wt%]]> 71.7 72.5 70.6 66.1 64.8 C5+ liquid / wt% 7.9 7.7 10.3 6.8 5.4 Aromatic content in C5+ liquid / wt% 94.6 97.2 91.9 86.5 84.9

[0101] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A carbon dioxide hydrogenation catalyst, characterized in that The carbon dioxide hydrogenation catalyst comprises 10-80 wt% of nano metal oxide and 20-90 wt% of modified ZSM-5 molecular sieve, wherein the nano metal oxide and modified ZSM-5 molecular sieve are treated with a silane coupling agent and then calcined to obtain the carbon dioxide hydrogenation catalyst; The nano metal oxide comprises component A and component B, wherein component A is selected from any three of iron oxide, cobalt oxide, molybdenum oxide, nickel oxide, and copper oxide, and component B is selected from any one of zirconium oxide, potassium oxide, and calcium oxide; The modified ZSM-5 molecular sieve comprises component a, component b and ZSM-5 molecular sieve, component a is selected from any one of lanthanum oxide and cerium oxide, and component b is selected from any one of potassium oxide and magnesium oxide.

2. The catalyst according to claim 1, characterized in that The weight percentage of component B in the nano metal oxide is 1 to 10%.

3. The catalyst according to claim 1, characterized in that The weight percentage of component a in the modified ZSM-5 molecular sieve is 0.1-5%, and the weight percentage of component b in the modified ZSM-5 molecular sieve is 0.1-3%.

4. The catalyst according to claim 1, characterized in that The silane coupling agent is KH560 and / or KH570.

5. A method for preparing the catalyst according to any one of claims 1 to 4, characterized in that: The steps include: (1) dissolving a first metal salt in deionized water, then adding sucrose and polyethylene glycol, stirring to obtain a sol, and drying and calcining the sol to obtain a nano-metal oxide; (2) dissolving a second metal salt in deionized water to obtain a second metal salt solution, aging the ZSM-5 molecular sieve, then impregnating the ZSM-5 molecular sieve with the second metal salt solution, allowing the mixture to stand, drying, and calcining to obtain a modified ZSM-5 molecular sieve; (3) The nano-metal oxide and the modified ZSM-5 molecular sieve are dispersed in deionized water, ethanol and a silane coupling agent are added, and the mixture is stirred thoroughly to obtain a slurry. The slurry is spray-dried to form a slurry, and then dried and calcined to obtain a carbon dioxide hydrogenation catalyst.

6. The preparation method according to claim 5, characterized in that In step (1), the stirring condition is stirring at 40-95° C. for 5-15 hours, the drying condition is drying at 110-120° C. for 10-15 hours, and the roasting condition is roasting at 400-600° C. for 5-15 hours.

7. The preparation method according to claim 5, characterized in that In step (1), the polyethylene glycol is PEG2000 and / or PEG4000; sucrose and polyethylene glycol account for 0.01-5% and 0.01-10% of the weight of the sol respectively.

8. The preparation method according to claim 5, characterized in that In step (2), the aging conditions are aging at 550-700°C for 2-5 hours, standing time is 10-15 hours, drying conditions are drying at 100-120°C for 8-15 hours, and roasting conditions are roasting at 500-600°C for 10-15 hours; the weight ratio of the second metal salt solution to the ZSM-5 molecular sieve is 5-7:10; the particle size of the ZSM-5 molecular sieve is <800nm, and the silicon-aluminum ratio is 80-300.

9. The preparation method according to claim 5, characterized in that In step (3), ethanol and silane coupling agent account for 0.5-3% and 1-5% of the weight of the slurry respectively.

10. The preparation method according to claim 5, characterized in that In step (3), the solid content of the slurry is 25 to 35 wt%.

11. Use of the catalyst according to any one of claims 1 to 4 in carbon dioxide hydrogenation reaction.