Catalyst for preparing toluene by coupling carbon dioxide hydrogenation with benzene alkylation as well as preparation method and application of catalyst

Abstract

The invention belongs to the field of synthesis of toluene by carbon dioxide, and provides a catalyst for preparation of toluene by hydrogenation coupling benzene alkylation of carbon dioxide, which comprises a CuGa / CeZrO2 intermediate and an HZSM-5 molecular sieve which are compounded by using hydrophobic silica sol as a binder raw material, the CuGa / CeZrO2 intermediate has double active sites of Cu and Ga, a cerium-zirconium solid solution CeZrO2 is used as a carrier, and the carrier is loaded with a Cu element and a Ga element; on the basis of the total mass of the CuGa / CeZrO2 intermediate, the loading capacity of the Cu element is 7wt%-10wt%, and the loading capacity of the Ga element is 1wt%-3wt%. The catalyst provided by the invention has high conversion rate and selectivity when being used for preparing toluene through carbon dioxide hydrogenation coupling benzene alkylation, and the yield of toluene is improved. In addition, the invention further provides a preparation method of the catalyst, the process is simple, raw materials are easy to obtain, and the catalyst is suitable for industrial popularization.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of synthesizing toluene from carbon dioxide, and particularly relates to a catalyst for synthesizing toluene from carbon dioxide and hydrogen coupling benzene alkylation, a preparation method and application thereof. BACKGROUND

[0002] Toluene is a key chemical basic raw material, and its traditional fossil energy synthesis route (such as petroleum aromatic hydrocarbon combination and coal coking benzene hydrogenation refining) faces challenges such as limited resources, low yield and poor quality. With the intensification of the contradiction between demand growth and resource depletion, developing non-fossil-dependent efficient toluene production technology has become a global focus. Based on the CO or CO2 emission reduction demand and the current situation of benzene overcapacity, using CO or CO2 / H2 to catalytically alkylate benzene to produce high-value aromatic hydrocarbons (such as toluene) has double strategic significance: on the one hand, it realizes the high-value utilization of CO or CO2, and on the other hand, it provides an innovative solution for upgrading and increasing the efficiency of excess benzene, with significant synergistic value.

[0003] At present, bifunctional catalysts (such as ZnZrO x / HZSM-5) and ternary composite catalysts (such as ZnZrO x -Al2O3-ZSM-5) are the mainstream catalysts for synthesizing toluene from CO2 hydrogenation coupling benzene alkylation, but the inherent thermodynamic stability of CO2 molecules severely limits the kinetic rate of hydrogenation to generate alkylation reagents, and increasing metal loading or increasing reaction temperature can accelerate the supply of intermediates, but it will also intensify the reverse water gas shift reaction and methanol decomposition side reaction.

[0004] CN119500242A discloses a preparation method of a bifunctional core-shell structure HZSM-5@Al2O3 catalyst, which is combined with a ZnZrOx catalyst and applied to a CO2 hydrogenation coupling benzene alkylation reaction, which can not only inhibit the self-reaction of intermediate methanol on the acid sites of the core HZSM-5 molecular sieve, but also dehydrate the intermediate methanol in advance, reducing the poisoning effect of water molecules on the acid sites of the core HZSM-5 molecular sieve, but the ZnZrO X has weak adsorption and activation ability for CO2, resulting in low CO2 conversion rate.

[0005] CN118056800A discloses a catalyst composed of an oxide material with carbon dioxide hydrogenation performance and a modified zeolite molecular sieve material combined by a proper method, which overcomes the problems of relatively slow carbon dioxide hydrogenation reaction rate and relatively low selectivity of high-value light aromatic hydrocarbon products such as toluene and dimethylbenzene, but the stability of the catalyst is poor.

[0006] CN113457724B discloses a bifunctional catalyst that can directly convert synthesis gas (CO+H2) and benzene to co-produce toluene and diphenylmethane. Compared with the traditional process of using chlorobenzene to produce diphenylmethane, which is polluting and high-risk, this patent uses synthesis gas and benzene as raw materials to avoid harmful emissions, but has limitations: when CO is the core reaction gas, an improper ratio of H2 can easily produce by-products such as dimethyl ether and low-carbon alkanes; and when CO is excessive, it may be over-hydrogenated to form methane or carbon nanotube precursors.

[0007] CN120001413A discloses a core-shell catalyst for the production of xylene by the hydrogenation of CO2 coupled with toluene alkylation (such as GaZrO x @ZSM-5), which can effectively avoid the interference of toluene with metal oxides and improve the conversion rate, but its preparation process is complex and has poor reproducibility, and the core-shell structure also causes diffusion limitation problems.

[0008] Therefore, it is important to continue to develop a catalyst with mild reaction conditions, high CO2 conversion rate, and good toluene selectivity. SUMMARY

[0009] To solve the above technical problems, the present application provides a carbon dioxide hydrogenation coupled with benzene alkylation to produce toluene catalyst, which not only improves the yield of methanol and toluene, but also further improves the stability of the entire catalyst system. The catalyst described in the present application provides a new idea for designing efficient carbon dioxide hydrogenation coupled with benzene alkylation to produce toluene reactions.

[0010] The basic concept of the technical solution adopted by the present application is as follows: A carbon dioxide hydrogenation coupled with benzene alkylation to produce toluene catalyst, which includes a CuGa / CeZrO2 intermediate and a HZSM-5 molecular sieve compounded by using hydrophobic silica sol as a binder raw material; the CuGa / CeZrO2 intermediate has Cu and Ga dual active sites, with a cerium-zirconium solid solution CeZrO2 as a carrier, and the carrier is loaded with Cu and Ga elements; based on the total mass of the CuGa / CeZrO2 intermediate, the loading amount of Cu is 7wt%-10wt%, and the loading amount of Ga is 1wt%-3wt%.

[0011] As one way, the molar ratio of Ce element to Zr element in the CeZrO2 carrier is (0.5-1):1.

[0012] As one way, the mass ratio of the CuGa / CeZrO2 intermediate to the HZSM-5 molecular sieve is (1-1.5):1.

[0013] As a mode, the molar ratio of Si element in the hydrophobic silica sol to Ce element in the CuGa / CeZrO2 intermediate is (6-10):1; the mass concentration of the hydrophobic silica sol is 30 wt% in terms of Si element.

[0014] The application also provides a preparation method of the carbon dioxide hydrogenation coupling benzene alkylation toluene catalyst as described in any one of the above. (1) preparing a Ce salt and Zr salt solution, mixing uniformly to form a mixed salt solution; At a reaction temperature, ammonia water is added to the mixed salt solution to form a precipitate, the precipitate is aged, filtered, washed, and dried to obtain a precursor; the precursor is calcined in an air atmosphere to obtain a CeZrO2 carrier; (2) preparing a mixed solution of Cu salt and Ga salt, adding powder of the CeZrO2 carrier, stirring uniformly, and impregnating at room temperature; then, after drying, calcining in an air atmosphere to obtain a CuGa / CeZrO2 catalyst; (3) adding the CuGa / CeZrO2 catalyst and HZSM-5 molecular sieve powder to a hydrophobic silica sol, stirring uniformly to form a gel; (4) drying and calcining the gel to obtain the carbon dioxide hydrogenation coupling benzene alkylation toluene catalyst.

[0015] As a mode, in the step (1), the reaction temperature is 50-90 ℃, 0.3-3 mol L -1 Ammonia water is used to control the pH value to be 7.5-9.5.

[0016] As a mode, in the step (1), the aging temperature is 50-90 ℃, the aging time is 20-80 min; the drying temperature is 70-150 ℃, the drying time is 6-15 h; the calcination temperature is 350-600 ℃, and the calcination time is 3-7 h.

[0017] As a mode, the drying temperature of the gel is 70-150 ℃, the drying time is 6-15 h, the calcination temperature is 300-500 ℃, and the calcination time is 4-7 h.

[0018] As a mode, in the step (2), the impregnation time is 12-24 h; the drying temperature is 70-150 ℃, the drying time is 6-15 h; the calcination temperature is 300-500 ℃, and the calcination time is 4-7 h; In the step (4), the drying temperature is 70-150 ℃, the drying time is 6-15 h, the calcination temperature is 300-500 ℃, and the calcination time is 4-7 h.

[0019] The application also relates to application of the catalyst in preparation of toluene by carbon dioxide hydrogenation coupling benzene alkylation.

[0020] Compared with the prior art, the application has the following beneficial effects: (1) The application is a catalyst for preparing toluene by CO2 catalytic hydrogenation coupling benzene alkylation, and the obtained CuGa / CeZrO2 / HZSM-5 catalyst is prepared by a coprecipitation method and an impregnation method, so that the process conditions are simple and raw materials are easy to obtain.

[0021] (2) The CuGa / CeZrO2 / HZSM-5 double active site catalyst provided by the application utilizes Cu to provide hydrogenation activity, and Ga promotes CO2 activation and stability of a key intermediate, so that the activity and methanol selectivity of the CO2 hydrogenation reaction are remarkably improved, and high CO2 conversion rate and high methanol yield can be realized under mild conditions.

[0022] (3) The application adopts a cerium-zirconium solid solution (CeZrO2) with excellent oxygen vacancy forming ability, good redox property and high thermal stability as a carrier. The carrier transfers electrons to Cu through its rich oxygen vacancies, so that the high-activity Cu 0 / Cu + species is stabilized; meanwhile, the introduction of Zr 4+ enhances the Lewis acidity of Ga, reduces the adsorption energy of CO2, and effectively solves the problem that pure Cu has weak CO2 adsorption capacity.

[0023] In addition, the CeZrO2 crystal lattice can effectively anchor Cu particles, and the four-element structure formed by Ga at the interface further inhibits the sintering of Cu, so that a continuous reaction interface is jointly constructed, and the utilization rate of active sites is remarkably improved. In the reaction path, the synergistic effect of Cu and CeZrO2 can stabilize the HCOO - intermediate, inhibit the generation of byproduct CO, and timely remove the accumulated carbon, thereby prolonging the service life of the catalyst. In comparison, the effect of using CeZrO2 or CuGa alone is poor, while the synergistic system can improve the selectivity of methanol and has high dispersity and excellent anti-sintering performance.

[0024] (4) In the reaction system of toluene prepared by CO2 hydrogenation coupling benzene alkylation, a large amount of water vapor is generated, which not only accelerates the deactivation of the catalyst, but also affects the yield of the product toluene. The CuGa / CeZrO2 catalyst and the HZSM-5 molecular sieve are compounded by hydrophobic silica gel, which is beneficial to the rapid diffusion and removal of the generated water, so as to promote the reaction equilibrium of methanol synthesis to move to the product direction, improve the yield of methanol and toluene, and further synergistically improve the stability of the entire catalyst system. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings are used to provide a further understanding of the technical solutions of the present application, constitute a part of the specification, and are used together with the embodiments of the present application to explain the technical solutions of the present application, and do not constitute a limitation on the technical solutions of the present application.

[0026] Figure 1 is a schematic diagram of a reaction device for preparing toluene by catalytic hydrogenation of CO2 and coupling with benzene according to the present application.

[0027] Figure 2 is a stability test result diagram of a catalyst running for 200 hours in embodiment 1 of the present application.

[0028] Markings in the figure: 1-CO2 / H2 mixed gas storage tank; 2-liquid benzene storage tank; 3-micro injection pump; 4-pressure reducing valve; 5-mass flow meter; 6-vaporization chamber; 7-gas mixing tank; 8-reactor; 9-back pressure valve; 10-cold trap; 11-gas chromatograph. DETAILED DESCRIPTION

[0029] To make the purposes, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the described embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0030] The catalyst of the present application is a new type of CuGa / CeZrO2 dual active site catalyst. The catalyst utilizes Cu to provide hydrogenation activity, and Ga to promote CO2 activation and stability of key intermediates. Meanwhile, a cerium-zirconium solid solution (CeZrO2) with excellent oxygen vacancy formation ability, redox property and high thermal stability is used as a carrier, which effectively improves the dispersion and sintering resistance of the CuGa active component. The construction of CuGa dual sites on the CeZrO2 carrier significantly improves the activity, methanol selectivity and catalyst stability of the CO2 hydrogenation to methanol reaction, and can realize high CO2 conversion and high methanol yield under mild conditions.

[0031] In addition, the CuGa / CeZrO2 catalyst is compounded with HZSM-5 molecular sieve through hydrophobic silica gel, which not only facilitates the rapid diffusion and removal of reaction generated water, thereby promoting the shift of methanol synthesis reaction equilibrium to the product direction and improving the yield of methanol and toluene, but also further cooperatively improves the stability of the entire catalyst system.

[0032] As an example, the loading amount of Cu element is 7 wt% ~ 10 wt%, and the loading amount of Ga element is 1 wt% ~ 3 wt% based on the total mass of the CuGa / CeZrO2 intermediate.

[0033] Preferably, the loading amount of Cu element is 7 wt% ~ 10 wt%, and the loading amount of Ga element is 1 wt% ~ 3 wt%.

[0034] As an example, the molar ratio of Ce element to Zr element in the CeZrO2 carrier is (0.5~1):1.

[0035] As an example, the mass ratio of the CuGa / CeZrO2 intermediate to HZSM-5 molecular sieve is (1~1.5):1.

[0036] As an example, the molar ratio of Si element in the hydrophobic silica sol to Ce element in the CuGa / CeZrO2 intermediate is (6~10):1.

[0037] As a specific example, the silicon-aluminum ratio of HZSM-5 molecular sieve is 14~17.

[0038] As an example, in step (1), the concentration of nitrate salt of Ce salt and Zr salt is 0.1~2.5 mol / L. -1

[0039] As an example, in step (2), Cu salt and Ga salt are nitrate salts, and the amount of addition, the volume of water and the mass of CeZrO2 carrier are calculated according to the loading amount and the water absorption rate of CeZrO2 carrier.

[0040] Figure 1 is an application scenario example of the carbon dioxide hydrogenation coupling benzene alkylation toluene catalyst described in the present application. Wherein, the liquid benzene from the liquid benzene storage tank 2 is first accurately delivered to the vaporization chamber 6 by the micro-injection pump 3 to complete vaporization, and then enters the gas mixing tank 7 with the CO2 / H2 mixed gas from the liquid benzene storage tank 2, and after being fully mixed and uniform, the mixed gas is delivered into the reactor 8. In the reactor 8, the components occur CO2 catalytic hydrogenation coupling benzene alkylation reaction to generate toluene under the action of specific temperature, pressure and catalyst. The mixed gas after the reaction first enters the cold trap 10, and the toluene therein is condensed into liquid product for collection; the remaining uncondensed tail gas is directly connected to the gas chromatograph 11 for subsequent component content analysis.

[0041] In the following comparative examples, ZnZrO X or GaZrO X ​The 'x' does not represent any specific stoichiometric coefficient; it is simply an abbreviation for "oxide," meaning "Zn-Zr-O mixed oxide" or "Ga-Zr-O mixed oxide."

[0042] The hydrophobic silica sol used in the following examples of the present invention has a mass concentration of 30 wt% (based on Si element) and a density of approximately 1.2 g / mL.

[0043] Example 1 In the prepared CuGa / CeZrO2 catalyst: the Cu element loading was 7 wt%, the Ga element loading was 3 wt%, and the molar ratio of cerium to zirconium was 1. The molar ratio of silicon to Ce in the hydrophobic silica sol was 10. The mass ratio of CuGa / CeZrO2 catalyst to HZSM-5 was 1, the silicon-to-aluminum ratio of the HZSM-5 molecular sieve was 15, and the water absorption rate of the CeZrO2 support was 0.8 mL g. -1 .

[0044] (1) Prepare solutions with a concentration of 1.25 mol / L. -1 Take 97.6 mL of Ce(NO3)3·6H2O and ZrO(NO3)2·5H2O solutions respectively, and mix the two solutions evenly to form a mixed salt solution; At a reaction temperature of 80 °C, 0.6 mol L⁻¹ was slowly added dropwise to the mixed solution. -1 Ammonia solution was prepared until the solution reached pH=9, forming a precipitate. The precipitate was aged at 80 °C for 60 min, filtered and washed to obtain the precursor, which was then dried at 110 °C for 10 h. The dried precursor was calcined at 350 °C for 4 h to obtain CeZrO2 support. (2) Dissolve 5.32 g Cu(NO3)2·3H2O and 3.59 g Ga(NO3)3·9H2O in 14.4 mL of deionized water and stir until clear. Take 18 g of support powder and add it to the above solution. Stir evenly and impregnate at room temperature for 12 h. After impregnation, dry the sample at 120 ℃ for 15 h and calcine at 400 ℃ for 4 h to obtain CuGa / CeZrO2 catalyst. (3) Take 10 g of CuGa / CeZrO2 catalyst and HZSM-5 molecular sieve powder respectively and add them to 26.0 mL of hydrophobic silica sol. Stir at 60 °C to form a uniform gel. (4) The above gel was dried at 150 °C for 12 h and then calcined at 300 °C for 4.5 h to finally obtain CuGa / CeZrO2 / HZSM-5 catalyst.

[0045] Example 2 In the prepared CuGa / CeZrO2 catalyst, the Cu element loading was 10 wt%, the Ga element loading was 3 wt%, and the molar ratio of cerium to zirconium was 1. The molar ratio of silicon to Ce element in the hydrophobic silica sol was 10, the mass ratio of CuGa / CeZrO2 catalyst to HZSM-5 was 1, the silica-alumina ratio of HZSM-5 molecular sieve was 15, and the water absorption of the carrier CeZrO2 was 0.8 mL g -1 .

[0046] (1) 1.25 mol L -1 of Ce(NO3)3·6H2O and ZrO(NO3)2·5H2O solutions were prepared respectively, 97.6 mL of Ce(NO3)3·6H2O and ZrO(NO3)2·5H2O solutions were taken respectively, and the two solutions were mixed uniformly to form a mixed salt solution; At a reaction temperature of 80 ℃, 0.6 mol L -1 of ammonia solution was slowly added to the mixed solution until the solution reached pH=9, a precipitate was formed, the precipitate was aged at 80 ℃ for 60 min, and then the precursor was obtained after filtration and washing, and then the dried precursor was dried at 110 ℃ for 10 h, and then the dried precursor was calcined at 350 ℃ for 4 h to obtain the CeZrO2 carrier; (2) 7.60 g of Cu(NO3)2·3H2O and 3.59 g of Ga(NO3)3·9H2O were dissolved in 13.9 mL of deionized water, stirred until clear, 17.4 g of carrier powder was added to the above solution, stirred uniformly, and then immersed at room temperature for 12 h, and then the immersed sample was dried at 120 ℃ for 15 h, and then calcined at 400 ℃ for 4 h to obtain the CuGa / CeZrO2 catalyst; (3) 10 g of CuGa / CeZrO2 catalyst and HZSM-5 molecular sieve powder were taken respectively and added to 25 mL of hydrophobic silica sol, and then stirred uniformly at 60 ℃ to form a uniform gel; (4) The above gel was dried at 150 ℃ for 12 h, and then calcined at 300 ℃ for 4.5 h, and finally the CuGa / CeZrO2 / HZSM-5 catalyst was obtained.

[0047] Example 3 The CuGa / CeZrO2 catalyst prepared in the example has a Cu element loading of 10 wt%, a Ga element loading of 1 wt%, and a cerium to zirconium molar ratio of 1. The hydrophobic silica sol has a silica to Ce element molar ratio of 10. The mass ratio of the CuGa / CeZrO2 catalyst to the HZSM-5 is 1. The HZSM-5 molecular sieve has a silica to alumina ratio of 15. The CeZrO2 support has a water absorption of 0.8 mL g -1 .

[0048] (1) 1.25 mol L -1 of Ce(NO3)3·6H2O and ZrO(NO3)2·5H2O solutions were prepared respectively. 97.6 mL of the Ce(NO3)3·6H2O and ZrO(NO3)2·5H2O solutions were taken respectively, and the two solutions were mixed uniformly to form a mixed salt solution; At a reaction temperature of 80 ℃, 0.6 mol L -1 of ammonia solution was slowly added dropwise into the mixed solution until the solution reached pH=9 to form a precipitate. The precipitate was aged at 80 ℃ for 60 min, and then was filtered and washed to obtain a precursor. The precursor was dried at 110 ℃ for 10 h, and then was calcined at 350 ℃ for 4 h to obtain a CeZrO2 support; (2) 7.60 g of Cu(NO3)2·3H2O and 1.20 g of Ga(NO3)3·9H2O were dissolved in 14.2 mL of deionized water, and stirred until clear. 17.8 g of the support powder was added into the above solution, and stirred uniformly. The sample after impregnation was dried at 120 ℃ for 15 h, and then was calcined at 400 ℃ for 4 h to obtain a CuGa / CeZrO2 catalyst; (3) 10 g of the CuGa / CeZrO2 catalyst and 10 g of the HZSM-5 molecular sieve powder were taken respectively into 25.5 mL of the hydrophobic silica sol, and stirred uniformly at 60 ℃ to form a uniform gel; (4) The gel was dried at 150 ℃ for 12 h, and then was calcined at 300 ℃ for 4.5 h to finally obtain a CuGa / CeZrO2 / HZSM-5 catalyst.

[0049] Example 4 The CuGa / CeZrO2 catalyst prepared in the example has a Cu element loading of 10 wt%, a Ga element loading of 1 wt%, and a cerium to zirconium molar ratio of 0.5. The hydrophobic silica sol has a silica to Ce element molar ratio of 10. The mass ratio of the CuGa / CeZrO2 catalyst to the HZSM-5 is 1. The HZSM-5 molecular sieve has a silica to alumina ratio of 15. The CeZrO2 support has a water absorption of 0.8 mL g -1 .

[0050] (1) Prepare 1.25 mol L of each -1 Take 69.8 mL of Ce(NO3)3·6H2O and 139.6 mL of ZrO(NO3)2·5H2O solutions respectively, and mix the two solutions evenly to form a mixed salt solution; At a reaction temperature of 80 °C, 0.6 mol L⁻¹ was slowly added dropwise to the mixed solution. -1 Ammonia solution was prepared until the solution reached pH=9, forming a precipitate. The precipitate was aged at 80 °C for 60 min, filtered and washed to obtain the precursor, which was then dried at 110 °C for 10 h. The dried precursor was calcined at 350 °C for 4 h to obtain CeZrO2 support. (2) Dissolve 7.60 g Cu(NO3)2·3H2O and 1.20 g Ga(NO3)3·9H2O in 14.2 mL of deionized water and stir until clear. Take 17.8 g of support powder and add it to the above solution. Stir evenly and impregnate at room temperature for 12 h. After impregnation, dry the sample at 120 ℃ for 15 h and calcine at 400 ℃ for 4 h to obtain CuGa / CeZrO2 catalyst. (3) Take 10 g of CuGa / CeZrO2 catalyst and HZSM-5 molecular sieve powder respectively and add them to 18.0 mL of hydrophobic silica sol. Stir evenly at 60 °C to form a homogeneous gel. (4) The above gel was dried at 150 °C for 12 h and then calcined at 300 °C for 4.5 h to finally obtain CuGa / CeZrO2 / HZSM-5 catalyst.

[0051] Example 5 In the prepared CuGa / CeZrO2 catalyst: the Cu element loading was 10 wt%, the Ga element loading was 1 wt%, and the molar ratio of cerium to zirconium was 1. The molar ratio of silicon to Ce in the hydrophobic silica sol was 10. The mass ratio of CuGa / CeZrO2 catalyst to HZSM-5 was 1.5, the silicon-to-aluminum ratio of the HZSM-5 molecular sieve was 15, and the water absorption rate of the CeZrO2 support was 0.8 mL g. -1 .

[0052] (1) Prepare 1.25 mol L of each -1 Take 97.6 mL of Ce(NO3)3·6H2O and ZrO(NO3)2·5H2O solutions respectively, and mix the two solutions evenly to form a mixed salt solution; At a reaction temperature of 80 °C, 0.6 mol L⁻¹ was slowly added dropwise to the mixed solution. -1 Ammonia solution was prepared until the solution reached pH=9, forming a precipitate. The precipitate was aged at 80 °C for 60 min, filtered and washed to obtain the precursor, which was then dried at 110 °C for 10 h. The dried precursor was calcined at 350 °C for 4 h to obtain CeZrO2 support. (2) Dissolve 7.60 g Cu(NO3)2·3H2O and 1.20 g Ga(NO3)3·9H2O in 14.2 mL of deionized water and stir until clear. Take 17.8 g of support powder and add it to the above solution. Stir evenly and impregnate at room temperature for 12 h. After impregnation, dry the sample at 120 ℃ for 15 h and calcine at 400 ℃ for 4 h to obtain CuGa / CeZrO2 catalyst. (3) Take 10 g of CuGa / CeZrO2 catalyst and 6.6 g of HZSM-5 molecular sieve powder respectively and add them to 25.5 mL of hydrophobic silica sol. Stir evenly at 60 °C to form a homogeneous gel. (4) The above gel was dried at 150 °C for 12 h and then calcined at 300 °C for 4.5 h to finally obtain CuGa / CeZrO2 / HZSM-5 catalyst.

[0053] Example 6 In the prepared CuGa / CeZrO2 catalyst: the Cu element loading was 10 wt%, the Ga element loading was 1 wt%, and the molar ratio of cerium to zirconium was 1. The molar ratio of silicon to Ce in the hydrophobic silica sol was 6. The mass ratio of CuGa / CeZrO2 catalyst to HZSM-5 was 1. The silicon-to-aluminum ratio of the HZSM-5 molecular sieve was 15. The water absorption rate of the CeZrO2 support was 0.8 mL g. -1 .

[0054] (1) Prepare 1.25 mol L of each -1 Take 97.6 mL of Ce(NO3)3·6H2O and ZrO(NO3)2·5H2O solutions respectively, and mix the two solutions evenly to form a mixed salt solution; At a reaction temperature of 80 °C, 0.6 mol L⁻¹ was slowly added dropwise to the mixed solution. -1 Ammonia solution was prepared until the solution reached pH=9, forming a precipitate. The precipitate was aged at 80 °C for 60 min, filtered and washed to obtain the precursor, which was then dried at 110 °C for 10 h. The dried precursor was calcined at 350 °C for 4 h to obtain CeZrO2 support. (2) 7.60 g Cu(N03)2-3H20 and 1.20 g Ga(N03)3-9H20 were dissolved in 14.2 mL deionized water, stirred until clear, 17.8 g of the support powder was added to the above solution, stirred uniformly, and then impregnated at room temperature for 12 h. The impregnated sample was dried at 120 °C for 15 h and then calcined at 400 °C for 4 h to obtain a CuGa / CeZr02 catalyst; (3) 10 g of CuGa / CeZr02 catalyst and HZSM-5 molecular sieve powder were respectively added to 15.3 mL of hydrophobic silica sol, and stirred uniformly at 60 °C to form a uniform gel; (4) The gel was dried at 150 °C for 12 h and then calcined at 300 °C for 4.5 h to finally obtain a CuGa / CeZr02 / HZSM-5 catalyst.

[0055] Comparative Example 1 The Cu / CeZr02 catalyst was prepared with a Cu element loading of 10 wt%, a cerium to zirconium molar ratio of 1, a molar ratio of silicon to Ce element in the hydrophobic silica sol of 10, a mass ratio of Cu / CeZr02 to HZSM-5 of 1, a silicon to aluminum ratio of HZSM-5 molecular sieve of 15, and a water absorption of the support CeZr02 of 0.8 mL g -1 .

[0056] (1) 1.25 mol L -1 of Ce(N03)3-6H20 and ZrO(N03)2-5H20 solutions were respectively prepared, 97.6 mL of the Ce(N03)3-6H20 and ZrO(N03)2-5H20 solutions were respectively taken, and the two solutions were mixed uniformly to form a mixed salt solution; At a reaction temperature of 80 °C, 0.6 mol L -1 of ammonia solution was slowly added dropwise to the mixed solution until the solution reached pH = 9, a precipitate was formed, the precipitate was aged at 80 °C for 60 min, and then the precipitate was filtered and washed to obtain a precursor. The dried precursor was calcined at 350 °C for 4 h to obtain a CeZr02 support; (2) 7.60 g Cu(N03)2-3H20 was dissolved in 14.4 mL deionized water, stirred until clear, 18.0 g of CeZr02 support powder was added to the above solution, stirred uniformly, and then impregnated at room temperature for 12 h. The impregnated sample was dried at 120 °C for 15 h and then calcined at 400 °C for 4 h to obtain a Cu / CeZr02 catalyst; (3) Take 10 g of Cu / CeZrO2 and HZSM-5 molecular sieve powder respectively and add them to 26.0 mL of hydrophobic silica sol. Stir evenly at 60 °C to form a homogeneous gel. (4) The above gel was dried at 150 °C for 12 h and then calcined at 300 °C for 4.5 h to finally obtain Cu / CeZrO2 / HZSM-5 catalyst.

[0057] Comparative Example 2 Preparation of CuGa / CeO2 catalyst: Cu element loading was 10 wt%, and Ga element loading was 1 wt%. The molar ratio of silicon to Ce in the hydrophobic silica sol was 10, the mass ratio of CuGa / CeO2 to HZSM-5 was 1, and the silicon-to-aluminum ratio of HZSM-5 molecular sieve was 15.

[0058] (1) Prepare 1.25 mol L -1 A Ce(NO3)3·6H2O solution was slowly added dropwise to a mixed solution at a reaction temperature of 80 °C. -1 Ammonia solution was prepared until the solution reached pH=9, forming a precipitate. The precipitate was aged at 80 °C for 60 min, filtered, washed, and then the precursor was obtained. It was then dried at 110 °C for 10 h, and the dried precursor was calcined at 350 °C for 4 h to obtain CeO2 support. (2) Dissolve 7.60 g Cu(NO3)2·3H2O and 1.15 g Ga(NO3)3·9H2O in 14.2 mL of deionized water and stir until clear. Add 17.8 g CeO2 support powder to the above solution and stir evenly. Impregnate at room temperature for 12 h. After impregnation, dry the sample at 120 ℃ for 15 h and calcine at 400 ℃ for 4 h to obtain CuGa / CeO2 catalyst. (3) Take 10 g of CuGa / CeO2 catalyst and HZSM-5 molecular sieve powder respectively and add them to 43.9 mL of hydrophobic silica sol. Stir evenly at 60 °C to form a homogeneous gel. (4) The above gel was dried at 150 °C for 12 h and then calcined at 300 °C for 4.5 h to finally obtain CuGa / CeO2 / HZSM-5 catalyst.

[0059] Comparative Example 3 (1) Weigh 14.87 g of zinc nitrate and 23.33 g of zirconium nitrate according to the Zn / (Zn+Zr) molar ratio of 0.4:1, dissolve them together in 100 mL of anhydrous ethanol, stir until completely dissolved, add HZSM-5 molecular sieve accounting for 40% of the total mass of the system, and continue stirring for 30 minutes to make the molecular sieve uniformly dispersed. (2) Subsequently, 10.57 g of oxalic acid was weighed and dissolved in 50 mL of anhydrous ethanol to prepare an oxalic acid ethanol solution. The solution was heated at 300 r·min -1 At a stirring rate, oxalic acid solution was added dropwise to the mixture of the above salt and molecular sieve, and stirring was maintained for 2 hours after the addition was completed. (3) Collect the precipitate by filtration using a Buchner funnel, wash it three times with anhydrous ethanol (50 mL each time) to remove residual nitrates, and put the washed precipitate into an oven and dry it at 110 °C for 12 hours. (4) Finally, transfer the dried solid to a quartz boat, place it in a tube furnace, and heat it in an argon atmosphere (flow rate 50 mL / min). -1 Under 400 °C for 4 hours, the mixture was then calcined in an air atmosphere (flow rate 50 mL / min). -1 The mixture is heated to 500℃ and calcined for 8 hours, then naturally cooled to obtain a product that combines the properties of Zn and ZrO. X Composite catalyst of active component and HZSM-5 molecular sieve.

[0060] Comparative Example 4 (1) Under the stirring condition of oil bath at 70 °C, 2.98 g of ammonium carbonate was completely dissolved in 100 mL of water to prepare a precipitant solution, and then slowly added dropwise to 100 mL of aqueous solution containing 0.51 g of gallium nitrate and 5.80 g of zirconium nitrate. After the addition was completed, stirring was continued at 70 °C for 2 h, followed by aging at room temperature for 2 h. The resulting solid was washed 5 times with 200 mL of deionized water, dried at 105 °C for 10 h, and then calcined in a muffle furnace at 500 °C for 3 h. The calcined solid was granulated and sieved to 30-40 mesh to obtain GaZrO. X Metal oxide particles.

[0061] (2) Weigh 0.25 g of the above GaZrO X The granules and 0.25 g of HZSM-5 molecular sieve were prepared for use. For the initial coating, GaZrO was wetted with 0.04 mL of 30 wt% silica sol. X The particles were transferred to a container pre-filled with 0.02 g of HZSM-5 molecular sieve and shaken to completely coat the particle surface. Any loose molecular sieve powder was then removed using a 60-mesh sieve. This coating process was repeated, increasing the amount of silica sol and HZSM-5 by 0.005 g each time, until all 0.25 g of HZSM-5 molecular sieve was used, yielding HZSM-5-coated GaZrO. X Particles.

[0062] (3) The coated particles were placed in an oven and dried at 50 °C for 12 h, and then transferred into a muffle furnace and calcined at 500 °C in air for 2 h to obtain GaZrO X HZSM-5 core-shell catalyst.

[0063] Comparative Example 5 The difference from Example 1 is that: In step (4), 10 g of CuGa / CeZrO2 and HZSM-5 molecular sieve powder were taken respectively for standby, and in the first coating, 4 mL of 30 wt% silica sol was used to wet the CuGa / CeZrO2 particles, which were transferred to a container pre-loaded with 1 g of HZSM-5 molecular sieve and shaken to make the molecular sieve completely coated on the surface of the particles, and then the easily detached molecular sieve powder was removed with a 60-mesh sieve; The coating process was repeated, and each time the amount of silica sol was increased by 2 mL and the amount of HZSM-5 was increased by 0.5 g compared with the previous time, until 10 g of HZSM-5 molecular sieve was completely used, to obtain a HZSM-5 coated CuGa / CeZrO2 catalyst.

[0064] Performance test The performance of the catalysts of Examples 1-6 and Comparative Examples 1-5 was evaluated using a fixed bed reactor.

[0065] The specific experimental method is as follows: 1 mL of 20-40 mesh catalyst was uniformly mixed with an equal volume of quartz sand and packed into the isothermal zone of the reactor. The reaction conditions were set as 350 °C, 3 MPa, the molar ratio of CO2 to H2 was 1:3, and the CO2 / H2 mixed gas volume space velocity (GHSV) was controlled at 6000 h -1 -1, and the mass space velocity of benzene was 1 h -1 -1. The gas phase product analysis used an online gas chromatography system with helium as the carrier gas and a TCD detector; by preparing a standard CO2 / H2 mixed gas with a known concentration, a peak area-concentration standard curve of each component was drawn, and the corresponding component content was calculated according to the sample peak area. The liquid phase product was analyzed offline, and was used to quantify the main product toluene and unreacted benzene collected in the cold trap; the analysis used n-hexane as an internal standard (well separated from benzene and toluene), first prepared benzene-toluene-n-hexane mixed standard liquids with different concentrations, and drew a "component peak area / internal standard peak area-concentration" standard curve, and finally calculated the content of benzene and toluene in the sample by the standard curve.

[0066] The performance test results are shown in Table 1.

[0067] Table 1 As can be seen from Table 1: The CO2 conversion rate and benzene conversion rate of the CuGa / CeZrO2 / HZSM-5 catalysts obtained by the embodiments 1-6 of the present application are obviously better than those of the catalysts of the comparative examples 1-5 not completely adopting the concept of the present application, and exhibit higher catalytic activity. Although the catalysts of the comparative example 1 do not add Ga and the catalysts of the comparative example 2 do not add Zr, the CO2 conversion rate and benzene conversion rate of the catalysts are obviously decreased.

[0068] It is worth noting that although the comparative examples 1-5 are comparable to some embodiments in terms of toluene selectivity, this is because the HZSM-5 molecular sieve itself has good alkylation selectivity, so when the intermediate methanol supply is insufficient, the toluene selectivity can still be maintained at a high level, but the efficiency of the whole reaction system is low.

[0069] The CO2 conversion rate of the comparative example 1 (without Ga) is significantly reduced from 14.5% to 8.3% compared with the embodiment 2 (both with 10% Cu loading), which proves that the Ga component is indispensable in promoting the activation of CO2 and stabilizing the key intermediates.

[0070] The CO2 conversion rate of the comparative example 2 (without Zr, i.e. CeO2 carrier) is reduced from 13.7% to 9.1% compared with the embodiment 3, which proves that the introduction of Zr 4+ to form a CeZrO2 solid solution carrier plays a key role in enhancing Lewis acidity, reducing CO2 adsorption energy and stabilizing active sites.

[0071] The comparative example 3 (ZnZrO X / HZSM-5) and the comparative example 4 (GaZrO X @HZSM-5 core-shell structure) represent the common catalyst systems in the prior art. The catalyst performance (such as CO2 conversion rate ~ 15%) of the embodiments 1-6 of the present application is much higher than that of the two (~ 8%), which indicates that the CuGa / CeZrO2 active center combination has an essential activity advantage compared with the Zn-based or Ga-Zr-based system.

[0072] The comparative example 5 (core-shell structure composite method) is prepared by a complex layer-by-layer coating method, and its CO2 conversion rate is much lower than that of the embodiments (such as 15.0% of the embodiment 1) of the present application prepared by simple mixing of hydrophobic silica gel. This proves that the catalyst composite method of the present application not only has a simple process and good repeatability, but also avoids the diffusion limitation problem that may be caused by the core-shell structure, and has advantages in activity and preparation efficiency.

[0073] In addition, the catalyst of the present application has high stability. Taking the catalyst of the embodiment 1 as an example, the catalyst is subjected to a 200 h stability test experiment under the reaction conditions, and by continuously monitoring the benzene conversion rate, CO2 conversion rate and other key indicators in the reaction process, the stability test results of the catalyst are as follows: Figure 2As shown in the figure Figure 2 It can be seen that the CuGa / CeZrO2 / HZSM-5 catalyst of Example 1 exhibits high stability within 200 h. The stability of the catalysts obtained in other examples of the present application is basically similar to that of Example 1.

[0074] Although the embodiments of the present application are disclosed as above, the content described is only the embodiments adopted for the purpose of facilitating the understanding of the present application, and is not intended to limit the present application. Any modification and change in the form and details can be made by any person skilled in the art without departing from the spirit and scope of the present application. The patent protection scope of the present application shall be subject to the scope defined by the appended claims.

Claims

1. A catalyst for the production of toluene by the hydrocarbonation of carbon dioxide coupled with the alkylation of benzene, characterized by, The catalyst comprises a CuGa / CeZrO2 intermediate and HZSM-5 molecular sieve which are compounded by using hydrophobic silica sol as a binder raw material; the CuGa / CeZrO2 intermediate has Cu and Ga double active sites and takes cerium-zirconium solid solution CeZrO2 as a carrier, and the carrier is loaded with Cu and Ga elements; The loading amount of Cu element is 7 wt% to 10 wt% and the loading amount of Ga element is 1 wt% to 3 wt% based on the total mass of the CuGa / CeZrO2 intermediate.

2. The catalyst for the production of toluene by phenylalkylation coupled with carbon dioxide hydrogenation according to claim 1, characterized in that, The molar ratio of Ce element to Zr element in the CeZrO2 carrier is (0.5-1):

1.

3. The catalyst for the production of toluene by phenylalkylation coupled with carbon dioxide hydrogenation according to claim 1, characterized in that, The mass ratio of the CuGa / CeZrO2 intermediate to HZSM-5 molecular sieve is (1-1.5):

1.

4. The catalyst for the production of toluene by phenylalkylation coupled with carbon dioxide hydrogenation according to claim 1, characterized in that, The molar ratio of Si element in the hydrophobic silica sol to Ce element in the CuGa / CeZrO2 intermediate is (6-10):1, and the mass concentration of the hydrophobic silica sol is 30 wt% in terms of Si element.

5. The process for preparing a catalyst for the production of toluene by the coupling of carbon dioxide hydrogenation and benzene alkylation according to any one of claims 1 to 4, characterized in that, The catalyst comprises: (1) preparing a Ce salt and Zr salt solution, mixing uniformly to form a mixed salt solution; adding ammonia water to the mixed salt solution to form a precipitate at a reaction temperature, and aging, filtering, washing and drying the precipitate to obtain a precursor; and calcining the precursor in an air atmosphere to obtain a CeZrO2 carrier; (2) preparing a mixed solution of Cu salt and Ga salt, adding powder of the CeZrO2 carrier, stirring uniformly, and impregnating at room temperature; and then drying and calcining in an air atmosphere to obtain a CuGa / CeZrO2 catalyst; (3) adding the CuGa / CeZrO2 catalyst and HZSM-5 molecular sieve powder to hydrophobic silica sol, stirring uniformly to form a gel; (4) drying and calcining the gel to obtain the catalyst for preparing toluene by carbon dioxide hydrogenation coupling benzene alkylation.

6. The preparation method according to claim 5, characterized in that, The reaction temperature in step (1) is 50-90℃, and 0.3-3 mol L -1 Ammonia water, control pH value is 7.5-9.

5.

7. The preparation method according to claim 5, characterized in that, In step (1), the aging temperature is 50-90 ℃, the aging time is 20-80 min, the drying temperature is 70-150 ℃, the drying time is 6-15 h, and the calcination temperature is 350-600 ℃ and the calcination time is 3-7 h.

8. The preparation method according to claim 5, characterized in that, The drying temperature of the gel is 70-150 ℃, the drying time is 6-15 h, the calcination temperature is 300-500 ℃, and the calcination time is 4-7 h.

9. The preparation method according to claim 5, characterized in that, In step (2), the impregnation time is 12-24 h, the drying temperature is 70-150 ℃, the drying time is 6-15 h, the calcination temperature is 300-500 ℃, and the calcination time is 4-7 h; In step (4), the drying temperature is 70-150 ℃, the drying time is 6-15 h, the calcination temperature is 300-500 ℃, and the calcination time is 4-7 h.

10. The catalyst according to any one of claims 1-4 for use in preparing toluene by carbon dioxide hydrogenation coupling benzene alkylation.

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