Difunctional molecular sieve catalyst for coproduction of ethylbenzene by hydrogenation of carbon dioxide and preparation method thereof

Abstract

The invention relates to the technical field of catalyst preparation, in particular to a bifunctional molecular sieve catalyst for coproduction of ethylbenzene by hydrogenation of carbon dioxide and a preparation method thereof. The preparation method comprises the following steps: 1) modifying a molecular sieve; 2) preparing a bifunctional molecular sieve catalyst; and 3) molding the molecular sieve catalyst. In the preparation process of the bifunctional molecular sieve catalyst, a fluorosilicate modified molecular sieve is used as a catalyst precursor, copper salt, zinc salt and a silicon source are loaded by accurately controlling a coprecipitation method, and carbon dioxide hydrogenation is performed on the outer layer (Cu / Zn / Si main part) of the catalyst to obtain methanol; and methanol further reacts with toluene in the inner layer (the main body part of the molecular sieve) of the catalyst to obtain a target product ethylbenzene, so that the bifunctional molecular sieve catalyst with excellent physical and chemical properties is finally realized. The stability of the catalyst prepared by the technology is remarkably improved, the yield of a target product is relatively high, and a new way is provided for resource utilization of carbon dioxide.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst preparation, and particularly to a bifunctional molecular sieve catalyst for hydrogenating carbon dioxide to co-produce ethylbenzene and a preparation method thereof. Background Art

[0002] In the contemporary chemical industry, ethylbenzene, as an important organic synthesis raw material, is mainly used to produce styrene, and then obtain styrene homopolymers and copolymers (such as ABS, AS, etc.) mainly composed of styrene. Ethylbenzene can also be used as an intermediate for chloramphenicol and chloramphenicol in medicine, and can also be used to prepare fragrances.

[0003] Traditional ethylbenzene production processes mostly use benzene and ethylene (ethylene in the non-petroleum route is produced from syngas (or carbon dioxide and hydrogen) through methanol) to produce ethylbenzene, or produce methanol from syngas (or carbon dioxide and hydrogen), and then the methanol reacts with toluene by side-chain alkylation to obtain ethylbenzene products. The above processes have disadvantages such as long routes, high catalyst bed temperature (550 - 650 °C), high energy consumption, and high raw material costs.

[0004] The conversion of carbon dioxide to aromatics via methanol is one of the new technological directions that have attracted the attention of scientific researchers in recent years. This technology has the advantages of wide and cheap raw material sources, short process flow, low bed temperature, low process energy consumption, and low comprehensive product cost. If the catalyst technology bottleneck can be broken through, its technical economy is particularly significant. For example, in the invention patent CN110743609A, a combined catalyst was developed to realize the process of hydrogenating carbon dioxide to couple with toluene alkylation to produce xylene, using carbon dioxide and hydrogen instead of methanol to avoid the problem of fluctuating xylene yield caused by the methanol / toluene ratio; however, since the xylene product is still a mixture, the product still needs to be separated, and the product separation cost is relatively high. Moreover, the stability of this catalyst is poor, the xylene selectivity decreases rapidly, and the anti-coking performance is still difficult to guarantee, and the catalyst life is short. Therefore, it is still necessary to develop and utilize this technology. Summary of the Invention

[0005] The purpose of the present invention is to provide a bifunctional molecular sieve catalyst for hydrogenating carbon dioxide to co-produce ethylbenzene and a preparation method thereof, in order to at least solve one of the problems existing in the current prior art. In the preparation process of this bifunctional molecular sieve catalyst, the molecular sieve modified by fluorosilicate is used as the catalyst precursor, and copper salt, zinc salt, and silicon source are loaded by precisely controlling the co-precipitation method. Carbon dioxide is hydrogenated to methanol in the outer layer of the catalyst (the Cu / Zn / Si main part), and methanol further reacts with toluene in the inner layer of the catalyst (the molecular sieve main part) to obtain the target product ethylbenzene, and finally a bifunctional molecular sieve catalyst with excellent physical and chemical properties is obtained.

[0006] In order to achieve the above invention purpose, the specific technical solution of the present invention is as follows:

[0007] A preparation method of a bifunctional molecular sieve catalyst for hydrogenating carbon dioxide to co-produce ethylbenzene, which comprises the following steps:

[0008] 1) Modification of the molecular sieve

[0009] Put the fluorosilicate solution, deionized water and molecular sieve into a water bath and stir vigorously to obtain a mixed solution; then wash, filter and dry the mixed solution to obtain a molecular sieve catalyst intermediate;

[0010] 2) Preparation of the bifunctional molecular sieve catalyst

[0011] Weigh the copper salt, zinc salt, silicon source, deionized water and ethanol solution in a stoichiometric ratio. The mixed solution forms a gel under vigorous stirring in a water bath. After stirring, add the molecular sieve catalyst intermediate prepared in step A to the above gel, then ultrasonically mix, and finally put the above mixed solution into an oven for drying. Use a ball mill or mortar to grind the dried sample into powder to obtain a bifunctional molecular sieve precursor;

[0012] 3) Shaping of the molecular sieve catalyst

[0013] Weigh the bifunctional molecular sieve precursor, binder, deionized water and talc powder prepared in step 1) in a stoichiometric ratio, knead and stir evenly under heating conditions, and then obtain the required molecular sieve catalyst for hydrogenating carbon dioxide to co-produce ethylbenzene after extrusion molding, drying and calcination.

[0014] Preferably, in step 1) of the preparation method of the bifunctional molecular sieve catalyst for hydrogenating carbon dioxide to co-produce ethylbenzene, the addition amount of the fluorosilicate is 1-50% of the mass of the molecular sieve; the mass concentration of the fluorosilicate solution is 0.5-20%; the addition amount of deionized water is 100% of the mass of the molecular sieve; the temperature in the water bath is 60-99 °C, the stirring time is 2 h; the ultrasonic mixing time is 2 h; the temperature in the oven is 95-110 °C, and the drying time is 2-18 h.

[0015] Preferably, in step 1) of the preparation method of the bifunctional molecular sieve catalyst for hydrogenating carbon dioxide to co-produce ethylbenzene, the fluorosilicate is any one or a mixture of several of sodium fluorosilicate, potassium fluorosilicate, ammonium fluorosilicate; the molecular sieve is any one of ZSM-5, 13X, Y molecular sieves.

[0016] Preferably, in step 2) of the preparation method of the bifunctional molecular sieve catalyst for hydrogenating carbon dioxide to co-produce ethylbenzene, the addition amount of the zinc salt calculated as ZnO is 10-100% of the mass of the copper salt (calculated as CuO, the same below); the addition amount of the silicon source calculated as SiO 2It is 50-200% of the mass of the copper salt; the addition amount of the deionized water is 10-200% of the mass of the copper salt; the addition amount of the ethanol solution is 10-200% of the mass of the copper salt; the addition amount of the molecular sieve catalyst intermediate is 50-200% of the mass of the copper salt.

[0017] Preferably, in step 2) of the preparation method of a bifunctional carbon dioxide hydrogenation co-producing ethylbenzene molecular sieve catalyst, the copper salt is one or a mixture of several of copper formate, copper bromide, and copper chloride; the zinc salt is any one or a mixture of several of diethylzinc, benzyl zinc bromide, and methyl zinc chloride solution; the silicon source is any one or a mixture of several of sodium silicate, silica sol, methyl orthosilicate, and ethyl orthosilicate solution.

[0018] Preferably, in step 3) of the preparation method of a bifunctional carbon dioxide hydrogenation co-producing ethylbenzene molecular sieve catalyst, the addition amount of the binder is 2-10% of the mass of the bifunctional molecular sieve precursor calculated as Al 2 O 3 ; the addition amount of the sesbania powder is 1-10% of the mass of the bifunctional molecular sieve precursor; the addition amount of the deionized water is 10-100% of the mass of the bifunctional molecular sieve precursor.

[0019] Preferably, in step 3) of the preparation method of a bifunctional carbon dioxide hydrogenation co-producing ethylbenzene molecular sieve catalyst, the binder is any one or a mixture of several of sodium metaaluminate, pseudo-boehmite, and aluminum hydroxide; the calcination temperature is 400-600 °C and the time is 1-6 h.

[0020] Preferably, in step 3) of the preparation method of a bifunctional carbon dioxide hydrogenation co-producing ethylbenzene molecular sieve catalyst, the catalyst sample obtained by extrusion is tapped and screened with a mortar rod, and particles with a particle size of 20-40 mesh are selected for use during the evaluation of the catalyst activity.

[0021] Another object of the present invention is to protect a bifunctional carbon dioxide hydrogenation co-producing ethylbenzene molecular sieve catalyst prepared by using any of the above method steps or combinations of steps.

[0022] Furthermore, the molecular sieve catalyst is a bifunctional molecular sieve catalyst; the bifunction means that the function of hydrogenating carbon dioxide to obtain methanol can be achieved on the outer layer of the catalyst, and the function of further reacting methanol with toluene to obtain the target product ethylbenzene can be achieved on the inner layer of the catalyst.

[0023] The third object of the present invention is to protect the application of the above-mentioned bifunctional carbon dioxide hydrogenation co-producing ethylbenzene molecular sieve catalyst in hydrogenating carbon dioxide to obtain methanol and reacting methanol with toluene to prepare ethylbenzene.

[0024] Preferably, the application includes the following steps: using carbon dioxide, hydrogen, and toluene as raw materials, reacting at a reaction temperature of 350°C - 480°C, a reaction pressure of 2 - 6 MPa, and a raw material mass space velocity of 0.1 h -1 -4.0 h -1 to produce ethylbenzene and by-product methanol; the molar ratio of carbon dioxide, hydrogen, and toluene in the raw materials is 1:3:0.1 - 10.

[0025] Compared with the existing technology, the beneficial effects of the present invention are:

[0026] (1) The present invention provides a method for preparing a molecular sieve catalyst for the co-production of ethylbenzene by hydrogenating carbon dioxide with dual functions, overcoming the problems of the long process route and high energy consumption of the molecular sieve catalyst in the prior art, where carbon dioxide is reacted to produce methanol and then undergoes side-chain alkylation reaction with toluene.

[0027] (2) In the present invention, by using fluorosilicate as a molecular sieve modifier, precisely controlling the molecular sieve modification process, and the feed ratio of the sol-gel method (SiO 2 / Al 2 O 3 / CuO), during the preparation of the molecular sieve catalyst, fluorosilicate has strong flexibility, can interact with the molecular sieve framework and cause certain deformation of the crystal, and finally form a hierarchical pore molecular sieve, which is more conducive to the smooth progress of this reaction.

[0028] (3) During the preparation of this dual-functional molecular sieve catalyst, using the molecular sieve modified with fluorosilicate as the catalyst precursor, precisely controlling the co-precipitation method to load copper salt, zinc salt, and silicon source onto the molecular sieve catalyst precursor, hydrogenating carbon dioxide to obtain methanol in the outer layer of the catalyst (the main part of Cu / Zn / Si), and further reacting methanol with toluene in the inner layer of the catalyst (the main part of the molecular sieve) to obtain the target product ethylbenzene, ultimately realizing a dual-functional molecular sieve catalyst with excellent physical and chemical properties.

[0029] The present invention loads SiO 2 / Al 2 O 3 / CuO components onto the molecular sieve catalyst precursor by the co-precipitation method, and finally obtains a dual-functional molecular sieve catalyst sample with an excellent pore structure, making SiO 2 / Al 2 O 3The methanol produced on the / CuO surface diffuses rapidly and continues to react with toluene on the surface of the modified molecular sieve to form ethylbenzene, which promotes the right shift of the reaction, ultimately increasing the conversion rate of carbon dioxide hydrogenation. To a certain extent, it also inhibits the methane side reaction, ultimately increasing the conversion rate of carbon dioxide. At the same time, during the hydrothermal treatment process, fluorosilicate can also promote the aggregation of nano-molecular sieve particles to form larger aggregates, thus solving the problem of difficult washing and filtration of nano-molecular sieve particle slurries.

[0030] (4) By optimizing the preparation conditions of the molecular sieve catalyst, such as the fluorosilicate modification temperature, modification time, etc., the present invention changes the physical and chemical properties of the molecular sieve catalyst material, such as pore size distribution, crystal size, etc., and ultimately effectively improves the selectivity and yield of ethylbenzene. Description of the Drawings

[0031] Figure 1 It is a schematic flow chart of the preparation method of a bifunctional molecular sieve catalyst for carbon dioxide hydrogenation to co-produce ethylbenzene according to the present invention. Detailed Embodiments

[0032] All the features disclosed in this specification, or all the steps in any method or process disclosed, except for mutually exclusive features and / or steps, can be combined in any way.

[0033] Any feature disclosed in this specification (including the claims, abstract) can be replaced by other equivalent or similar-purpose alternative features, unless specifically stated otherwise. That is, unless specifically stated, each feature is only an example of a series of equivalent or similar features.

[0034] The features and properties of the present invention will be further described in detail below in conjunction with embodiments.

[0035] Comparative Example 1

[0036] The raw material components of the catalyst in this comparative example are as follows:

[0037] Weigh 100 parts (by weight, 1 part can be regarded as 1 kg or 1 g, the same below) of copper nitrate (calculated by the mass of CuO), and weigh 50 parts of zinc nitrate in terms of ZnO; in terms of SiO 2 Calculate, weigh 50 parts of tetraethyl orthosilicate; 100 parts of the deionized water;

[0038] In terms of Al 2 O 3 Calculate, weigh 4 parts of sodium aluminate; weigh 2 parts of sesbania powder; weigh an appropriate amount of deionized water. This catalyst is prepared from the above raw material components by the following method:

[0039] a) According to the described component ratios, weigh out the copper salt (copper nitrate), zinc salt (zinc nitrate), and silicon source (tetraethyl orthosilicate) in the measured ratios. The mixed solution forms a gel under vigorous stirring in a water bath at 80 °C. After stirring for 2 h, place the above mixed solution in an oven at 105 °C and dry for 10 h. Use a ball mill to grind the dried sample into powder to obtain the bifunctional molecular sieve precursor;

[0040] c) Weigh out the measured ratios of the bifunctional molecular sieve precursor prepared in step B, binder (sodium metaaluminate), deionized water, and carboxymethyl cellulose. Knead and stir evenly under heating conditions, then extrude into shape, dry, and calcine (550 °C, 3 h) to obtain the required catalyst.

[0041] Example 1:

[0042] The raw material components of the bifunctional molecular sieve catalyst in this example are:

[0043] Based on the mass of the molecular sieve, weigh out 100 parts of H-ZSM-5 molecular sieve; 10 parts of sodium fluorosilicate (with a mass concentration of 2%); based on H 2 O, 100 parts of deionized water;

[0044] Weigh out 100 parts of copper formate (based on the mass of CuO), 50 parts of diethylzinc based on ZnO; 50 parts of tetraethyl orthosilicate based on SiO 2 ; 150 parts of the above deionized water; 50 parts of ethanol; 100 parts of the molecular sieve catalyst intermediate;

[0045] Based on Al 2 O 3 , weigh out 4 parts of sodium metaaluminate; 2 parts of carboxymethyl cellulose; weigh out an appropriate amount of deionized water. The bifunctional molecular sieve catalyst is prepared from the above component raw materials through the following method:

[0046] a) According to the described component ratios, first, for the above fluorosilicate solution, add deionized water to dissolve and dilute, then add the molecular sieve, stir evenly, place in a water bath at 80 °C, and stir vigorously for 2 h. Then wash, filter, and dry the obtained mixed solution to obtain the molecular sieve catalyst intermediate;

[0047] b) Weigh out the measured ratios of copper salt, zinc salt, silicon source, deionized water, and ethanol solution. The mixed solution forms a gel under vigorous stirring in a water bath at 80 °C. After stirring for 2 h, add the molecular sieve catalyst intermediate prepared in step A to the above gel, then ultrasonically mix for 2 h. Finally, place the above mixed solution in an oven at 105 °C and dry for 10 h. Use a ball mill to grind the dried sample into powder to obtain the bifunctional molecular sieve precursor;

[0048] c) Weigh the bifunctional molecular sieve precursor, binder, deionized water, and sesbania powder prepared in step B in a stoichiometric ratio, knead and stir evenly under heating conditions, and then obtain the required molecular sieve catalyst for the co-production of ethylbenzene by hydrogenation of carbon dioxide through extrusion molding, drying, and calcination (550 °C, 3 h).

[0049] Example 2

[0050] The raw material components of the bifunctional molecular sieve catalyst in this example are:

[0051] Based on the mass of the molecular sieve, weigh 100 parts of H-ZSM-5 molecular sieve; 1 part of potassium fluorosilicate (with a mass concentration of 20%); based on H 2 O, 100 parts of deionized water;

[0052] Weigh 100 parts of copper bromide (based on the mass of CuO), and based on ZnO, weigh 10 parts of benzylzinc bromide; based on SiO 2 Calculate, weigh 100 parts of methyl orthosilicate; 10 parts of the above-mentioned deionized water; weigh 200 parts of ethanol; weigh 50 parts of the molecular sieve catalyst intermediate;

[0053] Based on Al 2 O 3 Calculate, weigh 2 parts of aluminum hydroxide; weigh 10 parts of sesbania powder; weigh an appropriate amount of deionized water. The bifunctional molecular sieve catalyst is prepared from the above raw material components by the following method:

[0054] a) According to the described component ratio, first add the above-mentioned fluorosilicate solution, dissolve and dilute it with deionized water, then add the molecular sieve, stir evenly, place it in a water bath at 60 °C, and stir vigorously for 2 h. Then wash, filter, and dry the obtained mixed solution to obtain the molecular sieve catalyst intermediate;

[0055] b) Weigh the copper salt, zinc salt, silicon source, deionized water, and ethanol solution in a stoichiometric ratio. The mixed solution forms a gel under vigorous stirring in a water bath at 80 °C. After stirring for 2 h, add the molecular sieve catalyst intermediate prepared in step A to the above gel, then ultrasonically mix for 2 h, and finally place the above mixed solution in an oven at 95 °C and dry for 18 h. Use a mortar to grind the dried sample into powder to obtain the bifunctional molecular sieve precursor;

[0056] c) Weigh the bifunctional molecular sieve precursor, binder, deionized water, and sesbania powder prepared in step B in a stoichiometric ratio, knead and stir evenly under heating conditions, and then obtain the required molecular sieve catalyst for the co-production of ethylbenzene by hydrogenation of carbon dioxide through extrusion molding, drying, and calcination (600 °C, 1 h).

[0057] Example 3

[0058] The raw material components of the bifunctional molecular sieve catalyst in this example are:

[0059] Weigh 100 parts of Y-type molecular sieve based on the mass of the molecular sieve; 25 parts of ammonium fluorosilicate (with a mass concentration of 10%); based on H 2 O, 100 parts of deionized water;

[0060] Weigh 100 parts of copper chloride (based on the mass of CuO), and 10 parts of benzylzinc bromide based on ZnO; based on SiO 2 Weigh 200 parts of sodium silicate; 200 parts of the above-mentioned deionized water; weigh 10 parts of ethanol; weigh 200 parts of the molecular sieve catalyst intermediate;

[0061] Based on Al 2 O 3 Weigh 10 parts of pseudoboehmite; weigh 1 part of sesbania powder; weigh an appropriate amount of deionized water. The bifunctional molecular sieve catalyst is prepared from the above component raw materials by the following method:

[0062] a) According to the component ratio described above, first, the above-mentioned fluorosilicate solution is added to deionized water, dissolved and diluted, then added to the molecular sieve, stirred evenly, and then placed in a water bath at 99°C and stirred vigorously for 2 h. Then, the obtained mixed solution is washed, filtered, and dried to obtain the molecular sieve catalyst intermediate;

[0063] b) Weigh the copper salt, zinc salt, silicon source, deionized water, and ethanol solution in the stoichiometric ratio. The mixed solution forms a gel under vigorous stirring in a water bath at 80°C. After stirring for 2 h, the molecular sieve catalyst intermediate prepared in step A is added to the above gel, and then ultrasonically mixed for 2 h. Finally, the above mixed solution is placed in an oven at 110°C and dried for 2 h. The dried sample is ground into powder using a mortar to obtain the bifunctional molecular sieve precursor;

[0064] c) Weigh the bifunctional molecular sieve precursor, binder, deionized water, and sesbania powder prepared in step B in the stoichiometric ratio, knead and stir evenly under heating conditions, and then extrude into shape, dry, and calcine (400°C, 6 h) to obtain the required molecular sieve catalyst for the co-production of ethylbenzene by hydrogenation of carbon dioxide.

[0065] Example 4

[0066] The raw material components of the bifunctional molecular sieve catalyst in this example are:

[0067] Weigh 100 parts of 13X-type molecular sieve based on the mass of the molecular sieve; 50 parts of ammonium fluorosilicate (with a mass concentration of 0.5%); based on H 2 O, 100 parts of deionized water;

[0068] Weigh 100 parts of copper chloride (based on the mass of CuO), and 100 parts of methylzinc chloride based on ZnO; based on SiO 2Weigh 100 parts of silica sol; 150 parts of deionized water; weigh 20 parts of ethanol; weigh 100 parts of molecular sieve catalyst intermediate;

[0069] Based on Al 2 O 3 weigh 5 parts of pseudoboehmite; weigh 5 parts of sesbania powder; weigh an appropriate amount of deionized water.

[0070] The bifunctional molecular sieve catalyst is prepared from the above component raw materials by the following method:

[0071] a) According to the component ratio described above, first add the above-mentioned fluorosilicate solution, dissolve and dilute it with deionized water, then add the molecular sieve, stir evenly, place it in an 85°C water bath and stir vigorously for 2 h, and then wash, filter and dry the obtained mixed solution to obtain the molecular sieve catalyst intermediate;

[0072] b) Weigh the copper salt, zinc salt, silicon source, deionized water and ethanol solution in the stoichiometric ratio. The mixed solution forms a gel under vigorous stirring in an 80°C water bath. After stirring for 2 h, add the molecular sieve catalyst intermediate prepared in step A to the above gel, then ultrasonically mix for 2 h, and finally place the above mixed solution in an oven at 105°C and dry for 2 h. Use a ball mill to grind the dried sample into powder to obtain the bifunctional molecular sieve precursor;

[0073] c) Weigh the bifunctional molecular sieve precursor, binder, deionized water and sesbania powder prepared in step B in the stoichiometric ratio, knead and stir evenly under heating conditions, and then extrude, dry and calcine (500°C, 4 h) to obtain the required molecular sieve catalyst for the co-production of ethylbenzene by carbon dioxide hydrogenation.

[0074] Example 5

[0075] The raw material components of the bifunctional molecular sieve catalyst in this example are:

[0076] Based on the mass of the molecular sieve, weigh 100 parts of 13X type molecular sieve; 40 parts of ammonium fluorosilicate (with a mass concentration of 2%); based on H 2 O, 100 parts of deionized water;

[0077] Weigh 20 parts of copper formate (based on the mass of CuO), weigh 10 parts of copper bromide (based on the mass of CuO), based on ZnO, weigh 10 parts of diethylzinc, weigh 10 parts of benzylzinc bromide; based on SiO 2 weigh 50 parts of tetraethyl orthosilicate; 20 parts of the deionized water; weigh 100 parts of ethanol; weigh 100 parts of molecular sieve catalyst intermediate;

[0078] Based on Al 2 O 3Weigh 3 portions of pseudoboehmite; weigh 3 portions of sesbania powder; weigh an appropriate amount of deionized water. The bifunctional molecular sieve catalyst is prepared from the above raw materials by the following method:

[0079] a) According to the component ratio, first, the above-mentioned fluorosilicate solution is added with deionized water, dissolved and diluted, then molecular sieve is added, stirred evenly, and then placed in a water bath at 90 °C and stirred vigorously for 2 h. Then, the obtained mixed solution is washed, filtered and dried to obtain the molecular sieve catalyst intermediate;

[0080] b) Weigh the copper salt, zinc salt, silicon source, deionized water and ethanol solution in a stoichiometric ratio. The mixed solution forms a gel under vigorous stirring in a water bath at 90 °C. After stirring for 2 h, the molecular sieve catalyst intermediate prepared in step A is added to the above gel, and then ultrasonically mixed for 2 h. Finally, the above mixed solution is placed in an oven at 105 °C and dried for 2 h. The dried sample is ground into powder using a ball mill to obtain the bifunctional molecular sieve precursor;

[0081] c) Weigh the bifunctional molecular sieve precursor, binder, deionized water and sesbania powder prepared in step B in a stoichiometric ratio, knead and stir evenly under heating conditions, and then extrude into shape, dry and calcine (550 °C, 3 h) to obtain the required molecular sieve catalyst for the co-production of ethylbenzene by hydrogenation of carbon dioxide.

[0082] Comparative Example 2:

[0083] The catalyst was prepared in the same manner as in Example 1, except that the molecular sieve was SAPO molecular sieve, and the other steps were the same.

[0084] Comparative Example 3:

[0085] The catalyst was prepared in the same manner as in Example 1, except that sodium fluorosilicate was replaced by magnesium borosilicate, and the other steps were the same.

[0086] In order to investigate the catalytic activity of the catalyst of the present invention, the molecular sieve catalyst samples prepared in the above comparative examples and examples were knocked and sieved to 20-40 mesh, and the catalytic activity of the catalysts in each example and comparative example for the reaction of hydrogenation of carbon dioxide coupled with toluene was evaluated. The specific evaluation method was as follows:

[0087] A fixed-bed stainless steel reactor was used. The catalyst loading was 1.5 g. Using carbon dioxide, hydrogen and toluene as raw materials, the molar ratio of carbon dioxide, hydrogen and toluene in the raw materials was 1:3:3. At a reaction temperature of 400 °C, 4 MPa, and a raw material mass space velocity of 0.5 h -1 (based on toluene). The activity evaluation data of the catalyst after 4 h of reaction are shown in Table 1 specifically:

[0088] Table 1 Comparison table of reaction activity data of catalysts

[0089]

[0090] As can be seen from Table 1, the activity evaluation data of the catalyst after 4 hours of reaction is specifically shown in Table 1. After 150 hours of reaction, the conversion rate of carbon dioxide is still maintained at more than 35%, and the selectivity of ethylbenzene is about 40.5%, indicating that the catalyst has good stability and a long life cycle; combined with the activity evaluation data, it can be found that the catalyst has a higher toluene conversion rate and ethylbenzene selectivity.

[0091] In summary, the present invention overcomes the problems of poor stability, long process route, large investment and high cost of molecular sieve catalysts in the prior art, and provides a method for preparing a molecular sieve catalyst for co-production of ethylbenzene by hydrogenation of carbon dioxide. The catalyst prepared by this method has high ethylbenzene selectivity and yield, a long catalyst life cycle, a simple preparation process, great technical and economic value and industrial promotion significance, and also expands new ways for the resource utilization of carbon dioxide, which is conducive to achieving the dual carbon goals as soon as possible.

[0092] The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.

[0093] This background section is provided to generally present the context of the invention, and the work of the presently named inventors, the work to the extent described in this background section, and aspects of this section that did not constitute prior art at the time of application are neither explicitly nor implicitly admitted to be prior art to the present invention.

Claims

1. A method for preparing a bifunctional carbon dioxide hydrogenation co-production ethylbenzene molecular sieve catalyst, characterized in that The catalyst has the functions of being used for hydrogenating carbon dioxide to obtain methanol and reacting methanol with toluene to obtain ethylbenzene. The preparation method comprises the following steps: 1) Modification of molecular sieves The fluorosilicate solution, deionized water and molecular sieve are placed in a water bath and stirred vigorously to obtain a mixed solution; the mixed solution is then washed, filtered and dried to obtain a molecular sieve catalyst intermediate; 2) Preparation of bifunctional molecular sieve catalysts Weigh copper salt, zinc salt, silicon source, deionized water and ethanol solution in a stoichiometric ratio, and stir the mixed solution vigorously in a water bath to form a gel. After stirring, add the molecular sieve catalyst intermediate prepared in step A to the gel, and then mix it by ultrasonication. Finally, put the mixed solution into an oven to dry, and use a ball mill or mortar to grind the dried sample into powder to obtain a bifunctional molecular sieve precursor. 3) Molecular sieve catalyst molding The bifunctional molecular sieve precursor, binder, deionized water and sesbania powder prepared in step 1) are weighed in a stoichiometric ratio, kneaded and stirred evenly under heating conditions, and then extruded, dried and calcined to obtain the desired bifunctional molecular sieve catalyst for the hydrogenation of carbon dioxide to produce ethylbenzene.

2. The method for preparing a bifunctional carbon dioxide hydrogenation and ethylbenzene co-production molecular sieve catalyst according to claim 1, characterized in that: In step 1), the amount of fluorosilicate added is 1-50% of the mass of the molecular sieve; the mass concentration of the fluorosilicate solution is 0.5-20%; the amount of deionized water added is 100% of the mass of the molecular sieve; the temperature in the water bath is 60-90°C, the stirring time is 2h; the ultrasonic mixing time is 2h; the temperature in the oven is 95-110°C, and the drying time is 2-18h.

3. The method for preparing a bifunctional carbon dioxide hydrogenation and ethylbenzene co-production molecular sieve catalyst as claimed in claim 2, characterized in that: In step 1), the fluorosilicate is any one of sodium fluorosilicate, potassium fluorosilicate, and ammonium fluorosilicate, or a mixture of several of them; and the molecular sieve is any one of ZSM-5, 13X, and Y molecular sieves.

4. The method for preparing a bifunctional carbon dioxide hydrogenation and ethylbenzene co-production molecular sieve catalyst according to claim 1, characterized in that: In step 2), the amount of zinc salt added is 10-100% of the mass of copper salt calculated as ZnO; the amount of silicon source added is 50-200% of the mass of copper salt calculated as SiO2; the amount of deionized water added is 10-200% of the mass of copper salt; the amount of ethanol solution added is 10-200% of the mass of copper salt; the amount of molecular sieve catalyst intermediate added is 50-200% of the mass of copper salt.

5. The method for preparing a bifunctional carbon dioxide hydrogenation and ethylbenzene co-production molecular sieve catalyst as claimed in claim 4, characterized in that: In step 2), the copper salt is one or a mixture of copper formate, copper bromide, and copper chloride; the zinc salt is any one or a mixture of diethyl zinc, benzyl zinc bromide, and methyl zinc chloride solution; the silicon source is any one or a mixture of sodium silicate, silica sol, methyl orthosilicate, and ethyl orthosilicate solution.

6. The method for preparing a bifunctional carbon dioxide hydrogenation and ethylbenzene co-production molecular sieve catalyst according to claim 1, characterized in that: In step 3), the amount of the binder added is 2-10% of the mass of the bifunctional molecular sieve precursor calculated as Al2O3; the amount of the sesbania powder added is 1-10% of the mass of the bifunctional molecular sieve precursor; and the amount of the deionized water added is 10-100% of the mass of the bifunctional molecular sieve precursor.

7. The method for preparing a bifunctional carbon dioxide hydrogenation and ethylbenzene co-production molecular sieve catalyst according to claim 6, characterized in that: In step 3), the binder is any one of sodium aluminate, pseudo-boehmite and aluminum hydroxide or a mixture of several thereof.

8. A bifunctional carbon dioxide hydrogenation co-production of ethylbenzene molecular sieve catalyst prepared by the method according to any one of claims 1 to 7.

9. Use of the bifunctional carbon dioxide hydrogenation and ethylbenzene co-production molecular sieve catalyst as claimed in claim 8 in the hydrogenation of carbon dioxide to obtain methanol and in the reaction of methanol and toluene to prepare ethylbenzene.

10. The use according to claim 9, characterized in that The process comprises the following steps: using carbon dioxide, hydrogen and toluene as raw materials, at a reaction temperature of 350°C-480°C, a reaction pressure of 2-6 MPa, and a raw material mass space velocity of 0.1 h -1 -4.0h -1 Ethylbenzene is produced under the conditions of , and methanol is produced as a by-product; the molar ratio of carbon dioxide, hydrogen and toluene in the raw materials is 1:3:0.1-10.

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