Heteropoly acid modified CuNiCeZrO X Process for the preparation of a catalyst

Abstract

The application relates to the technical field of dimethyl carbonate synthesis, and discloses a heteropoly acid modified CuNiCeZrO X catalyst preparation method, CuNiCeZrO X The molar ratio of metal elements in the catalyst in terms of oxides is Ce:Zr:Ni:Cu=(10-5):(7-4):(3-1):1, and the preparation method comprises the following steps: S1, preparing a solution by mixing nitrate active components of cerium, zirconium, nickel and copper with a template agent, slowly adding an alkaline aqueous solution into the solution, then heating to 70-90 DEG C, keeping for 3-6 hours, filtering, moving the filter cake into a muffle furnace for calcination, and obtaining CuNiCeZrO X composite oxide catalyst powder; S2, slowly adding a heteropoly acid solution into the CuNiCeZrO X composite oxide catalyst powder, ultrasonicating, standing and drying, and then moving into a muffle furnace for calcination, and obtaining the heteropoly acid modified CuNiCeZrO X catalyst; S3, mixing the heteropoly acid modified CuNiCeZrO X catalyst particles and the physical water absorption agent particles, and obtaining the heteropoly acid modified CuNiCeZrO X catalyst. The catalyst prepared by the application has high catalytic activity, strong stability and long service life in catalyzing the direct synthesis of DMC from methanol and CO2, and can effectively inhibit the occurrence of side reactions.

Description

Technical Field

[0001] This invention belongs to the field of dimethyl carbonate (DMC) synthesis technology, specifically relating to a heteropolyacid-modified CuNiCeZrO X Catalyst preparation methods. Background Technology

[0002] Dimethyl carbonate (DMC) is an environmentally friendly chemical in the emerging field of "green chemistry." Its molecule contains numerous organic functional groups, such as methoxy, carbonyl, and methyl groups, which can serve as potential components in methylation and carbonylation reactions, replacing toxic precursors such as dimethyl sulfate (DMS) and phosgene. DMC is also an environmentally friendly and clean raw material for the production of polycarbonate plastics and is widely used as a fuel additive, organic solvent, and electrolyte in lithium-ion batteries.

[0003] Methods for synthesizing DMC include phosgene reaction, transesterification, urea alcoholysis, methanol oxidative carbonylation, and direct synthesis from methanol and CO2. Among these, the phosgene reaction, methanol oxidative carbonylation, and transesterification are already industrially applied. However, due to the high toxicity of phosgene, the method for synthesizing DMC from phosgene has been abandoned. Methanol oxidative carbonylation and transesterification are widely used commercially, but they have certain drawbacks, including high reactant toxicity and equipment corrosion.

[0004] The direct synthesis of DMC from methanol and CO2 is gaining increasing attention due to its environmentally friendly nature and high atom efficiency. However, issues such as catalyst activity and stability have kept this reaction in the laboratory research stage. Designing and developing a high-efficiency, long-life catalytic system is key to achieving a breakthrough in this route. Studies have found that the acid-base sites of the catalyst play a crucial role in the direct synthesis of DMC from methanol and CO2, while oxygen vacancies on the surface of the active sites can promote CO2 adsorption and activation, thus improving the activation efficiency for CO2. Cerium-based catalysts exhibit good acid-base properties and show certain selectivity and activity in the synthesis of DMC from CO2 and methanol. The valence state of Ce also affects the concentration of oxygen vacancies. 3+ The higher the content, the higher the oxygen vacancy content. Compared with pure CeO2, transition metal oxide doping is more effective.

[0005] Invention patent CN112823879A discloses a metal-modified cerium-based catalyst, the active component of which is MxCe1-xOy (M is a metal element, one of Mn, Cu, Ti, Bi, Zr, Fe, Al, and Mg). At 140℃, the methanol conversion rate is 24.3%, and the DMC selectivity is 78.6%. Invention patent CN110479236A discloses a multi-element modified catalyst, the active component of which is one or more oxides of Ce, La, and Zr, with a maximum DMC yield of 4.13 mmol / g. Invention patent CN115414926A discloses a CeGaTi catalyst for CO2 catalytic conversion, with a maximum DMC yield of 24.64 mmol / g. Although some progress has been made, these catalytic activities and stability are still far from the level required for large-scale application. Invention patent CN114345319A discloses a modified nano-cerium dioxide catalyst, achieving a methanol conversion rate of up to 51.6% and a DMC selectivity of 99.6%, demonstrating significantly improved catalytic performance. However, this reaction uses 2-cyanopyridine as a dehydrating agent, and its hydration produces toxic 2-pyridinecarboxamide, which blocks the active sites of the catalyst, leading to a rapid decrease in catalyst activity. Currently, catalysts for the direct synthesis of DMC from methanol and CO2 generally suffer from low activity, poor stability, and numerous byproducts, keeping this reaction in the laboratory research stage. Designing and developing a catalytic system with high activity, long lifespan, and high selectivity is key to achieving a breakthrough in this route. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a heteropolyacid-modified CuNiCeZrO X Regarding the preparation method of the catalyst, firstly, addressing the problem of low activity in existing catalysts for the direct synthesis of DMC from methanol and CO2, this invention employs a template agent method to synthesize a quaternary CuNiCeZrO4 catalyst. X In composite oxide catalysts, doping with ZrO2 and NiO transition metal oxides improves the acid-base properties and oxygen vacancies on the CeO2 surface, while the addition of Cu promoters promotes Ce oxidation. 4+ To Ce 3+ Partial reduction increases the oxygen vacancy content, while also reacting with CeZrNiO. X Catalyst synergy enhances catalyst activity; Secondly, in view of the technical problem that existing catalysts for the direct synthesis of DMC from methanol and CO2 produce a large number of byproducts, this invention utilizes heteropolyacid modification to adjust the acid-base strength of the catalyst surface. The prepared catalyst promotes the conversion of methanol while maintaining the high selectivity of DMC. Thirdly, addressing the issue of poor stability in existing catalysts for the direct synthesis of DMC from methanol and CO2, this invention incorporates an inexpensive and reusable physical dehydrating agent during catalyst preparation. This improves the catalyst's lifespan while preventing side reactions during the catalytic reaction.

[0007] To achieve the aforementioned goals of enhancing catalytic activity, extending catalyst lifespan, and preventing side reactions, this invention provides the following technical solution: A heteropolyacid modified CuNiCeZrO X The method for preparing the catalyst, wherein CuNiCeZrO X The molar ratio of metal elements in the catalyst, calculated as oxides, is Ce:Zr:Ni:Cu = (10~5):(7~4):(3~1):1. The preparation method includes the following steps: S1: CuNiCeZrO X Preparation of composite oxide catalysts; Using cerium nitrate, zirconium nitrate, nickel nitrate, and copper nitrate as active components, the above active components and template agent are dissolved in water to obtain solution A; an alkaline aqueous solution is prepared to obtain solution B; Solution B was slowly added dropwise to solution A under continuous stirring to obtain a mixed solution. The temperature of the mixed solution was raised to 70-90℃ and maintained for 3-6 hours before filtration. The filter cake was washed, dried, and then calcined in a muffle furnace at 500-700℃ to obtain CuNiCeZrO. X Composite oxide catalyst powder; S2: Heteropolyacid modified CuNiCeZrO X Composite oxide catalysts; The heteropolyacid solution was slowly added dropwise to the CuNiCeZrO using an equal-volume impregnation method. X The composite oxide catalyst powder was ultrasonicated, allowed to stand, dried, and then calcined in a muffle furnace at 400-500℃ to obtain the heteropolyacid-modified CuNiCeZrO. X Composite oxidation catalyst; S3: Physical desiccant coupled with CuNiCeZrO X Composite oxidation catalyst; The heteropolyacid-modified CuNiCeZrO X The composite oxide catalyst is compressed into tablets, crushed, and sieved to obtain catalyst particles. A physical desiccant tablet is compressed, crushed, or directly crushed and sieved to obtain physical desiccant particles. The catalyst particles and the physical desiccant particles are mixed to obtain the heteropolyacid-modified CuNiCeZrO. X catalyst.

[0008] As one possible implementation, the template agent is one of hexadecyltrimethylammonium bromide, tetraethylammonium hydroxide, or tetrapropylammonium hydroxide, and the molar ratio of the template agent to the active component is 0.3~1.0:1.

[0009] As one possible implementation, the molar concentration of solution A is 0.1~1.0 mol / L.

[0010] As one possible implementation, solution B is one of NaOH, ammonia, NaCO3, NaHCO3, or urea solution, with a mass fraction of 10% to 40%.

[0011] As one possible implementation, solution B is slowly added dropwise to solution A under continuous stirring, while the temperature is maintained at 40~60°C.

[0012] As one possible implementation, the heteropoly acid is one of phosphoric acid, molybdenum phosphoric acid, tungstic acid, or tungstic silicate, with a mass fraction of 60% to 90%.

[0013] As one possible implementation, in step S1, the heating rate of the muffle furnace is 2~5℃ / min, and the calcination time is 5~10h.

[0014] As one possible implementation, the physical absorbent is one of 5A molecular sieve, 10X molecular sieve, hydrophilic SiO2, montmorillonite, and silica gel.

[0015] As one possible implementation, the catalyst particles and the physical desiccant particles have a particle size of 60-100 mesh.

[0016] As one possible implementation, the mass ratio of the catalyst particles to the physical desiccant particles is 0.5 to 2.

[0017] Compared with existing technologies, this invention provides a heteropolyacid-modified CuNiCeZrO X The catalyst preparation method has the following beneficial effects: First, this invention provides a method for preparing a CuNiCeZrOX quaternary composite oxide catalyst, which improves the catalyst activity and lifetime through organic template agent guidance, transition metal doping, heteropolyacid modification and coupling physical dehydrating agent.

[0018] Secondly, the heteropolyacid-modified CuNiCeZrOX catalyst prepared in this invention is applied to the CO2 and methanol synthesis of DMC reaction under mild reaction conditions (<200℃). The heteropolyacid modification is used to adjust the acid-base strength of the catalyst surface. The prepared catalyst promotes methanol conversion while maintaining high selectivity for DMC. The DMC yield in the fixed-bed multiphase reaction system is comparable to that in the homogeneous reactor.

[0019] Third, the physical dehydrating agent and heteropoly acid of this invention are both conventional chemical raw materials, which are widely available, inexpensive, suitable for large-scale production, have high reactivity, and improve the service life of the catalyst. Attached Figure Description

[0020] Figure 1 CuNiCeZrO X Gas chromatogram of the products from the synthesis of dimethyl carbonate from CO2 and methanol using catalysts. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1 A heteropolyacid modified CuNiCeZrO X The specific steps for preparing the catalyst are as follows: S1: Cu1Ni3Ce 10 Zr7O 38 Preparation of composite oxide catalysts; Weigh 5.47 g of cetyltrimethylammonium bromide (CTAB) as the template agent, and weigh 7.75 g of cerium nitrate, 5.64 g of zirconium nitrate, 1.31 g of nickel nitrate, and 0.44 g of copper nitrate as the active components. The molar ratio of the template agent to the active component is 0.3:1. Dissolve the template agent and active component in water and dilute to volume in a 500 mL volumetric flask to obtain a solution A with a concentration of 0.1 mol / L. Weigh 50.1 g of NaOH, dissolve it in water, and dilute to volume in a 500 mL volumetric flask to obtain a solution B with a mass fraction of 10%. Solution B was slowly added dropwise to solution A using a peristaltic pump. During the addition, solution A was continuously stirred at a constant temperature of 40°C. After the addition was complete, stirring was stopped to obtain a mixed solution. The temperature of the mixed solution was further increased to 70°C and maintained for 6 hours. The solution was then removed, filtered, and the filter cake was washed until no template agent residue remained. After drying at 100°C for 8 hours, the filter cake was placed in a porcelain dish and then transferred to a muffle furnace and heated to 500°C at a rate of 2°C / min for 10 hours to obtain the Cu1Ni3Ce. 10 Zr7O 38 catalyst; S2: Heteropolyacid modified Cu1Ni3Ce 10 Zr7O 38 catalyst Heteropolyacid modification was performed using an equal-volume impregnation method, where CuNiCeZrO prepared in step S1 was impregnated. X 6.76 g of catalyst powder was placed in a self-sealing bag. A 60% phosphoric acid solution was slowly added dropwise to the bag while continuously shaking. The bag was sealed after the solution reached saturation adsorption (no adsorption was observed visually during the slow addition process). The bag was then sonicated for 1.0 h, allowed to stand for 10 h, dried at 95℃ for 6 h, and then placed in a porcelain dish. The dish was then placed in a muffle furnace and calcined at 400℃ for 5 h at a rate of 2℃ / min to obtain the heteropolyacid-modified Cu1Ni3Ce. 10 Zr7O 38 catalyst; S3: Physical absorbent coupled with Cu1Ni3Ce 10 Zr7O 38 catalyst The 7.12 g of heteropolyacid-modified Cu1Ni3Ce prepared in step S2 10 Zr7O 38 The catalyst is compressed into tablets, crushed, and sieved to 60-100 mesh. The physical desiccant 5A molecular sieve (φ3-5mm, calcium sodium aluminosilicate compound, also known as calcium molecular sieve, chemical composition 3 / 4CaO·1 / 4Na2O·Al2O3·2SiO2·9 / 2H2O, pore size about 5Å) is ground and sieved to 60-100 mesh. The catalyst and the physical desiccant are mixed in a mass ratio of 0.5:1 to form 60-100 mesh particles, sealed, and placed in a desiccator for later use.

[0023] The catalyst prepared in this embodiment was applied to the synthesis of DMC from CO2 and methanol. The catalytic reaction was carried out in a fixed-bed reactor. The flow rate of CO2 was controlled by a mass flow meter at 10 mL / min, and the flow rate of methanol was controlled by a horizontal flow pump at a methanol liquid hourly space velocity (LHSV) of 1 h⁻¹. -1 After the catalyst was loaded into the reaction tube, 10% H2 / N2 was first introduced and the reduction treatment was carried out at 200℃ for 6 hours. After the reduction was completed, nitrogen was introduced to cool down. Then, CO2 and methanol were switched and preheated in an 80℃ preheating furnace before entering the reactor. The reaction temperature was 100℃ and the pressure was 6MPa. All reaction products were directly introduced into the gas chromatograph for online analysis through the heat-insulated pipeline. The catalyst and reaction conditions are listed in Table 1, and the reaction results are listed in Table 2.

[0024] Example 2 A heteropolyacid modified Cu1Ni1Ce5Zr4O 20 The specific steps for preparing the catalyst are as follows: S1: Cu1Ni1Ce5Zr4O 20 Preparation of composite oxide catalysts Weigh 73.63 g of tetraethylammonium hydroxide (TEAOH) as a template agent, and weigh 74.12 g of cerium nitrate, 61.68 g of zirconium nitrate, 8.32 g of nickel nitrate, and 8.54 g of copper nitrate as active components. Dissolve the template agent and active components in water at a molar ratio of 1:1, and dilute to volume in a 500 mL volumetric flask to obtain a solution A with a concentration of 1.0 mol / L. Weigh 200.3 g of urea, dissolve it in water, and dilute to volume in a 500 mL volumetric flask to obtain a solution B with a mass fraction of 40%. Solution B was slowly added dropwise to solution A using a peristaltic pump. During the addition, solution A was continuously stirred at a constant temperature of 60°C. After the addition was complete, stirring was stopped to obtain a mixed solution. The temperature of the mixed solution was further increased to 90°C and maintained for 3 hours. The solution was then removed, filtered, and the filter cake was washed until no template agent residue remained. After drying at 120°C for 4 hours, the cake was placed in a porcelain dish and calcined in a muffle furnace at a rate of 5°C / min to 700°C for 5 hours to obtain the Cu1Ni1Ce5Zr4O. 20 catalyst; S2: Heteropolyacid modified Cu1Ni1Ce5Zr4O 20 catalyst Heteropolyacid modification was performed using an equal-volume impregnation method, with 68.51 g of Cu1Ni1Ce5Zr4O prepared in step S1. 20 The catalyst powder was placed in a self-sealing bag, and 90% phosphoric acid solution was slowly added dropwise while continuously shaking. After saturation adsorption, the bag was sealed tightly, sonicated for 1.0 h, and allowed to stand for 15 h. Then, it was dried at 110℃ for 3 h, placed in a porcelain dish, and calcined in a muffle furnace at 5℃ / min to 500℃ for 3 h to obtain the heteropolyacid-modified Cu1Ni1Ce5Zr4O. 20 catalyst; S3: Physical desiccant coupled with Cu1Ni1Ce5Zr4O 20 catalyst 73.25g of heteropolyacid-modified Cu1Ni1Ce5Zr4O prepared in step S2 20 The catalyst is compressed into tablets, crushed, and sieved to 60-100 mesh. 5A molecular sieve (φ3-5mm) is ground and sieved to 60-100 mesh. The catalyst and the physical desiccant are mixed in a mass ratio of 2:1 to form 60-100 mesh particles, sealed, and placed in a desiccator for later use.

[0025] The catalyst prepared in this embodiment was applied to the synthesis of DMC from CO2 and methanol. The catalytic reaction was carried out in a fixed-bed reactor. The flow rate of CO2 was controlled by a mass flow meter at 200 mL / min, and the flow rate of methanol was controlled by a horizontal flow pump at a methanol liquid hourly space velocity (LHSV) of 20 h⁻¹. -1After the catalyst was loaded into the reaction tube, 10% H2 / N2 was first introduced and the reduction treatment was carried out at 300℃ for 3 hours. After the reduction was completed, nitrogen was introduced to cool down. Then, CO2 and methanol were switched and preheated in a 180℃ preheating furnace before entering the reactor. The reaction temperature was 200℃ and the pressure was 2MPa. All reaction products were directly introduced into the gas chromatograph for online analysis through the heat-insulated pipeline. The catalyst and reaction conditions are listed in Table 1, and the reaction results are listed in Table 2.

[0026] Example 3 A heteropolyacid modified Cu1Ni2Ce9Zr6O 33 The specific steps for preparing the catalyst are as follows: S1: Cu1Ni2Ce9Zr6O 33 Preparation of composite oxide catalysts Weigh 21.87 g of hexadecyltrimethylammonium bromide (CTAB) as the template agent, and weigh 24.46 g of cerium nitrate, 16.91 g of zirconium nitrate, 3.05 g of nickel nitrate, and 1.56 g of copper nitrate as the active components. Dissolve the template agent and active components in water at a molar ratio of 0.4:1, and dilute to volume in a 500 mL volumetric flask to obtain a solution A with a concentration of 0.3 mol / L. Measure 500 mL of ammonia solution and prepare a solution B with a mass fraction of 25%-28%. Solution B was slowly added dropwise to solution A using a peristaltic pump. During the addition, solution A was continuously stirred at a constant temperature of 45°C. After the addition was complete, stirring was stopped to obtain a mixed solution. The temperature of the mixed solution was further increased to 80°C and maintained for 4 hours. The solution was then removed, filtered, and the filter cake was washed until no template agent residue remained. After drying at 115°C for 5 hours, the cake was placed in a porcelain dish and calcined in a muffle furnace at a rate of 4°C / min to 650°C for 6 hours to obtain the Cu1Ni2Ce9Zr6O. 33 catalyst; S2: Heteropolyacid modified Cu1Ni2Ce9Zr6O 33 catalyst Heteropolyacid modification was performed using an equal-volume impregnation method, with 20.58 g of Cu1Ni2Ce9Zr6O prepared in step S1. 33 The catalyst powder was placed in a self-sealing bag, and 80% phosphoric acid solution was slowly added dropwise while continuously shaking. After saturation adsorption, the bag was sealed tightly, sonicated for 1.0 h, allowed to stand for 12 h, dried at 100℃ for 5 h, and then placed in a porcelain dish. The dish was then placed in a muffle furnace and calcined at 480℃ for 3.5 h at a rate of 3℃ / min to obtain the heteropolyacid-modified Cu1Ni2Ce9Zr6O. 33 catalyst; S3: Physical desiccant coupled with Cu1Ni2Ce9Zr6O 33 catalyst 23.71 g of heteropolyacid-modified Cu1Ni2Ce9Zr6O prepared in step S233 The catalyst is tableted, crushed, and sieved to 60-100 mesh. 10X molecular sieve (belonging to the calcium X type crystal structure, also known as calcium X molecular sieve, with a chemical composition of 4 / 5CaO·1 / 5Na2O·Al2O3·(2.6-3)SiO2·(6-7)H2O, a silicon-to-aluminum ratio of 2.6-3.0, and an effective pore size of approximately 9 Å) is tableted, crushed, and sieved to obtain 60-100 mesh particles. The catalyst and the physical desiccant are mixed at a mass ratio of 2:1 to obtain 60-100 mesh particles, sealed, and placed in a desiccator for later use.

[0027] The catalyst prepared in this embodiment was applied to the synthesis of DMC from CO2 and methanol. The catalytic reaction was carried out in a fixed-bed reactor. The flow rate of CO2 was controlled by a mass flow meter at 150 mL / min, and the flow rate of methanol was controlled by a horizontal flow pump at a methanol liquid hourly space velocity (LHSV) of 15 h⁻¹. -1 After the catalyst was loaded into the reaction tube, 10% H2 / N2 was first introduced and the reduction treatment was carried out at 280℃ for 3.5h. After the reduction was completed, nitrogen was introduced to cool down. Then, CO2 and methanol were switched and preheated in a 160℃ preheating furnace before entering the reactor. The reaction temperature was 180℃ and the pressure was 2.5MPa. All reaction products were directly sent to gas chromatography for online analysis through insulated pipelines. The catalyst and reaction conditions are listed in Table 1, and the reaction results are listed in Table 2.

[0028] Example 4 A heteropolyacid modified Cu1Ni1Ce 10 Zr4O 30 The specific steps for preparing the catalyst are as follows: S1: Cu1Ni1Ce 10 Zr4O 30 Preparation of composite oxide catalysts Weigh 18.41g of tetraethylammonium hydroxide (TEAOH) as the template agent, and weigh 50.96g of cerium nitrate, 20.21g of zirconium nitrate, 2.85g of nickel nitrate, and 2.93g of copper nitrate as the active components. Dissolve the template agent and active components in water at a molar ratio of 0.5:1, and dilute to volume in a 500mL volumetric flask to obtain a solution A with a concentration of 0.5mol / L. Weigh 150.2g of NaHCO3, dissolve it in water, and dilute to volume in a 500mL volumetric flask to obtain a solution B with a mass fraction of 30%. Solution B was slowly added dropwise to solution A using a peristaltic pump. Solution A was continuously stirred at a constant temperature of 50°C. After the addition was complete, stirring was stopped to obtain a mixed solution. The temperature of the mixed solution was further increased to 75°C and maintained for 5 hours. The solution was then removed, filtered, and the filter cake was washed until no template agent residue remained. After drying at 110°C for 6 hours, the cake was placed in a porcelain dish and calcined in a muffle furnace at a rate of 3°C / min to 600°C for 8 hours to obtain the Cu1Ni1Ce.10 Zr4O 30 catalyst; S2: Heteropolyacid modified Cu1Ni1Ce 10 Zr4O 30 catalyst Heteropolyacid modification was performed using an equal-volume impregnation method, with 36.84 g of Cu1Ni1Ce prepared in step S1. 10 Zr4O 30 The catalyst powder was placed in a self-sealing bag, and an 85% molybdenum phosphoric acid solution was slowly added dropwise to the bag while continuously shaking. After saturation adsorption, the bag was sealed tightly, sonicated for 1.0 h, allowed to stand for 14 h, dried at 105℃ for 4 h, and then placed in a porcelain dish. The dish was then placed in a muffle furnace and calcined at 460℃ for 4 h at a 2℃ / min rate to obtain the heteropolyacid-modified Cu1Ni1Ce. 10 Zr4O 30 catalyst; S3: Physical absorbent coupled with Cu1Ni1Ce 10 Zr4O 30 catalyst 38.19 g of heteropolyacid-modified Cu1Ni1Ce prepared in step S2 10 Zr4O 30 The catalyst is compressed into tablets, crushed, and sieved to 60-100 mesh. The hydrophilic SiO2 is compressed into tablets, crushed, and sieved to obtain particles with a particle size of 60-100 mesh. The catalyst and the physical desiccant are mixed in a mass ratio of 1.2:1 to obtain particles with a particle size of 60-100 mesh, sealed, and placed in a desiccator for later use.

[0029] The catalyst prepared in this embodiment was applied to the synthesis of DMC from CO2 and methanol. The catalytic reaction was carried out in a fixed-bed reactor. The CO2 flow rate was controlled by a mass flow meter at 180 mL / min, and the methanol flow rate was controlled by a horizontal flow pump at a methanol liquid hourly space velocity (LHSV) of 16 h⁻¹. -1 After the catalyst was loaded into the reaction tube, 10% H2 / N2 was first introduced and the reduction treatment was carried out at 250℃ for 4 hours. After the reduction was completed, nitrogen was introduced to cool down. Then, CO2 and methanol were switched and preheated in a 140℃ preheating furnace before entering the reactor. The reaction temperature was 160℃ and the pressure was 4MPa. All reaction products were directly introduced into the gas chromatograph for online analysis through the heat-insulated pipeline. The catalyst and reaction conditions are listed in Table 1, and the reaction results are listed in Table 2.

[0030] Example 5 A heteropolyacid modified Cu1Ni2Ce8Zr6O 31 The specific steps for preparing the catalyst are as follows: S1: Cu1Ni2Ce8Zr6O 31 Preparation of composite oxide catalysts Weigh 42.71 g of tetrapropylammonium hydroxide (TPAOH) as the template agent, and weigh 53.72 g of cerium nitrate, 41.91 g of zirconium nitrate, 7.52 g of nickel nitrate, and 3.86 g of copper nitrate as the active components. Dissolve the template agent and active components in water at a molar ratio of 0.6:1, and dilute to volume in a 500 mL volumetric flask to obtain a solution A with a concentration of 0.7 mol / L. Weigh 100.5 g of NaCO3, dissolve it in water, and dilute to volume in a 500 mL volumetric flask to obtain a solution B with a mass fraction of 20%. Solution B was slowly added dropwise to solution A using a peristaltic pump. Solution A was continuously stirred at a constant temperature of 55°C. Stirring was stopped after the addition was complete, resulting in a mixed solution. The temperature of the mixed solution was further increased to 80°C and maintained for 4 hours. The solution was then removed, filtered, and the filter cake was washed until no template agent residue remained. It was dried at 105°C for 7 hours and then placed in a porcelain dish. The dish was then placed in a muffle furnace and heated to 580°C at a rate of 2°C / min for 7 hours to obtain Cu1Ni2Ce8Zr6O. 31 catalyst; S2: Heteropolyacid modified Cu1Ni2Ce8Zr6O 31 catalyst Heteropolyacid modification was performed using an equal-volume impregnation method, with 48.14 g of Cu1Ni2Ce8Zr6O prepared in step S1. 31 The catalyst powder was placed in a self-sealing bag, and a 75% tungsten phosphoric acid solution was slowly added dropwise to the bag while continuously shaking. After saturation adsorption, the bag was sealed tightly, sonicated for 1.0 h, allowed to stand for 13 h, dried at 100℃ for 4 h, and then placed in a porcelain dish. The dish was then placed in a muffle furnace and calcined at 440℃ for 4.5 h at a rate of 2℃ / min to obtain heteropolyacid-modified Cu1Ni2Ce8Zr6O. 31 catalyst; S3: Physical desiccant coupled with Cu1Ni2Ce8Zr6O 31 catalyst 49.84 g of heteropolyacid-modified Cu1Ni2Ce8Zr6O prepared in step S2 31 The catalyst is compressed into tablets, crushed, and sieved to 60-100 mesh. Montmorillonite powder is compressed into tablets, crushed, and sieved to obtain particles with a particle size of 60-100 mesh. The catalyst and the physical desiccant are mixed at a mass ratio of 0.8:1 to obtain particles with a particle size of 60-100 mesh, sealed, and placed in a desiccator for later use.

[0031] The catalyst prepared in this embodiment was applied to the synthesis of DMC from CO2 and methanol. The catalytic reaction was carried out in a fixed-bed reactor. The CO2 flow rate was controlled by a mass flow meter at 100 mL / min, and the methanol flow rate was controlled by a horizontal flow pump at a methanol liquid hourly space velocity (LHSV) of 10 h⁻¹. -1After the catalyst was loaded into the reaction tube, 10% H2 / N2 was first introduced and the reduction treatment was carried out at 240℃ for 4.5h. After the reduction was completed, nitrogen was introduced to cool down the reaction. Then, CO2 and methanol were switched and preheated in a 130℃ preheating furnace before entering the reactor. The reaction temperature was 150℃ and the pressure was 4.5MPa. All reaction products were directly introduced into the gas chromatograph for online analysis through the heat-insulated pipeline. The catalyst and reaction conditions are listed in Table 1, and the reaction results are listed in Table 2.

[0032] Example 6 A heteropolyacid modified Cu1Ni1Ce7Zr5O 26 The specific steps for preparing the catalyst are as follows: (1) Cu1Ni1Ce7Zr5O 26 Preparation of composite oxide catalysts Weigh 73.21g of tetrapropylammonium hydroxide (TPAOH) as the template agent, and 73.38g of cerium nitrate, 54.52g of zirconium nitrate, 5.87g of nickel nitrate, and 6.03g of copper nitrate as the active components. Dissolve the template agent and active components in water at a molar ratio of 0.8:1, and dilute to volume in a 500mL volumetric flask to obtain a solution A with a concentration of 0.9mol / L. Measure 500mL of ammonia solution and prepare a solution B with a mass fraction of 25%-28%. Solution B was slowly added dropwise to solution A using a peristaltic pump. Solution A was continuously stirred at a constant temperature of 50°C. Stirring was stopped after the addition was complete, resulting in a mixed solution. The temperature of the mixed solution was further increased to 85°C and maintained for 5 hours. The solution was then removed, filtered, and the filter cake was washed until no template agent residue remained. After drying at 115°C for 5 hours, the cake was placed in a porcelain dish and calcined in a muffle furnace at 3°C / min to 600°C for 6 hours to obtain the Cu1Ni1Ce7Zr5O. 26 catalyst; S2: Heteropolyacid modified Cu1Ni1Ce7Zr5O 26 catalyst Heteropolyacid modification was performed using an equal-volume impregnation method, with 63.29 g of Cu1Ni1Ce7Zr5O prepared in step S1. 26 The catalyst powder was placed in a self-sealing bag, and a 65% tungstic acid solution was slowly added dropwise to the bag while continuously shaking. After saturation adsorption, the bag was sealed tightly, sonicated for 1.0 h, allowed to stand for 11 h, dried at 102℃ for 5 h, and then placed in a porcelain dish. The dish was then placed in a muffle furnace and calcined at 420℃ for 5 h at a rate of 3℃ / min to obtain heteropolyacid-modified Cu1Ni1Ce7Zr5O. 26 catalyst; S3: Physical desiccant coupled with Cu1Ni1Ce7Zr5O 26 catalyst 66.27 g of heteropolyacid-modified Cu1Ni1Ce7Zr5O prepared in step S226 The catalyst is compressed into tablets, crushed, and sieved to 60-100 mesh. The silica gel particles are crushed and sieved to obtain particles with a diameter of 60-100 mesh. The catalyst and the physical desiccant are mixed at a mass ratio of 0.6:1 to obtain particles with a diameter of 60-100 mesh, sealed, and placed in a desiccator for later use.

[0033] The catalyst prepared in this embodiment was applied to the synthesis of DMC from CO2 and methanol. The catalytic reaction was carried out in a fixed-bed reactor. The flow rate of CO2 was controlled by a mass flow meter at 50 mL / min, and the flow rate of methanol was controlled by a horizontal flow pump at a methanol liquid hourly space velocity (LHSV) of 6 h⁻¹. -1 After the catalyst was loaded into the reaction tube, 10% H2 / N2 was first introduced and the reduction treatment was carried out at 220℃ for 5 hours. After the reduction was completed, nitrogen was introduced to cool down. Then, CO2 and methanol were switched and preheated in a 100℃ preheating furnace before entering the reactor. The reaction temperature was 120℃ and the pressure was 5MPa. All reaction products were directly introduced into the gas chromatograph for online analysis through the heat-insulated pipeline. The catalyst and reaction conditions are listed in Table 1, and the reaction results are listed in Table 2.

[0034] Example 7 A heteropolyacid modified Cu1Ni3Ce6Zr4O 24 The specific steps for preparing the catalyst are as follows: S1: Cu1Ni3Ce6Zr4O 24 Preparation of composite oxide catalysts Weigh 32.80 g of hexadecyltrimethylammonium bromide (CTAB) as a template agent, and weigh 13.98 g of cerium nitrate, 9.69 g of zirconium nitrate, 3.92 g of nickel nitrate, and 1.34 g of copper nitrate as active components. Dissolve the template agent and active components in water at a molar ratio of 0.7:1, and dilute to volume in a 500 mL volumetric flask to obtain a solution A with a concentration of 0.2 mol / L. Weigh 125.4 g of NaCO3, dissolve it in water, and dilute to volume in a 500 mL volumetric flask to obtain a solution B with a mass fraction of 25%. Solution B was slowly added dropwise to solution A using a peristaltic pump. Solution A was continuously stirred at a constant temperature of 55°C. Stirring was stopped after the addition was complete, resulting in a mixed solution. The temperature of the mixed solution was further increased to 88°C and maintained for 3.5 hours. The solution was then removed, filtered, and the filter cake was washed until no template agent residue remained. It was dried at 120°C for 5 hours, then placed in a porcelain dish and calcined in a muffle furnace at a rate of 4°C / min to 680°C for 5.5 hours to obtain Cu1Ni3Ce6Zr4O. 24 catalyst; S2: Heteropolyacid modified Cu1Ni3Ce6Zr4O 24 catalyst Heteropolyacid modification was performed using an equal-volume impregnation method, with 13.04 g of Cu1Ni3Ce6Zr4O prepared in step S1. 24 The catalyst powder was placed in a self-sealing bag, and a 70% molybdenum phosphoric acid solution was slowly added dropwise while continuously shaking. After saturation adsorption, the bag was sealed tightly, sonicated for 1.0 h, allowed to stand for 10 h, dried at 105℃ for 4 h, and then placed in a porcelain dish. The dish was then placed in a muffle furnace and calcined at 480℃ for 3.5 h at a rate of 3.5℃ / min to obtain heteropolyacid-modified Cu1Ni3Ce6Zr4O. 24 catalyst; S3: Physical desiccant coupled with Cu1Ni3Ce6Zr4O 24 catalyst 14.97 g of heteropolyacid-modified Cu1Ni3Ce6Zr4O prepared in step S2 24 The catalyst is compressed into tablets, crushed, and sieved to 60-100 mesh. The 10X molecular sieve is compressed into tablets, crushed, and sieved to obtain particles with a particle size of 60-100 mesh. The catalyst and the physical desiccant are mixed at a mass ratio of 1.5:1 to obtain particles with a particle size of 60-100 mesh, sealed, and placed in a desiccator for later use.

[0035] The catalyst prepared in this embodiment was applied to the synthesis of DMC from CO2 and methanol. The catalytic reaction was carried out in a fixed-bed reactor. The CO2 flow rate was controlled by a mass flow meter at 30 mL / min, and the methanol flow rate was controlled by a horizontal flow pump at a methanol liquid hourly space velocity (LHSV) of 3 h⁻¹. -1 After the catalyst was loaded into the reaction tube, 10% H2 / N2 was first introduced and the reduction treatment was carried out at 210℃ for 5.5h. After the reduction was completed, nitrogen was introduced to cool down. Then, CO2 and methanol were switched and preheated in a 90℃ preheating furnace before entering the reactor. The reaction temperature was 110℃ and the pressure was 5.5MPa. All reaction products were directly sent to gas chromatography for online analysis through insulated pipelines. The catalyst and reaction conditions are listed in Table 1, and the reaction results are listed in Table 2.

[0036] Example 8 A heteropolyacid modified Cu1Ni3Ce9Zr5O 32 The specific steps for preparing the catalyst are as follows: S1: Cu1Ni3Ce9Zr5O 32 Preparation of composite oxide catalysts Weigh 54.67 g of hexadecyltrimethylammonium bromide (CTAB) as the template agent, and weigh 40.76 g of cerium nitrate, 23.56 g of zirconium nitrate, 7.61 g of nickel nitrate, and 2.60 g of copper nitrate as the active components. Dissolve the template agent and active components in water at a molar ratio of 0.6:1, and dilute to volume in a 500 mL volumetric flask to obtain a solution A with a concentration of 0.5 mol / L. Weigh 50.2 g of NaOH, dissolve it in water, and dilute to volume in a 500 mL volumetric flask to obtain a solution B with a mass fraction of 10%. Solution B was slowly added dropwise to solution A using a peristaltic pump. Solution A was continuously stirred at a constant temperature of 50°C. Stirring was stopped after the addition was complete, resulting in a mixed solution. The temperature of the mixed solution was further increased to 80°C and maintained for 4 hours. The solution was then removed, filtered, and the filter cake was washed until no template agent residue remained. It was dried at 110°C for 6 hours and then placed in a porcelain dish. The dish was then placed in a muffle furnace and calcined at 650°C for 7 hours at a rate of 3°C / min to obtain Cu1Ni3Ce9Zr5O. 32 catalyst; S2: Heteropolyacid modified Cu1Ni3Ce6Zr4O 24 catalyst Heteropolyacid modification was performed using an equal-volume impregnation method, with 34.15 g of Cu1Ni3Ce9Zr5O prepared in step S1. 32 The catalyst powder was placed in a self-sealing bag, and 80% phosphoric acid solution was slowly added dropwise while continuously shaking. After the solution was added until saturation adsorption, the bag was sealed tightly, sonicated for 1.0 h, allowed to stand for 12 h, dried at 105℃ for 5 h, and then placed in a porcelain dish. The dish was then placed in a muffle furnace and calcined at 450℃ for 4 h at a rate of 3℃ / min to obtain heteropolyacid-modified Cu1Ni3Ce9Zr5O. 32 catalyst; S3: Physical desiccant coupled with Cu1Ni3Ce9Zr5O 32 catalyst 36.22 g of heteropolyacid-modified Cu1Ni3Ce9Zr5O prepared in step S2 32 The catalyst is compressed into tablets, crushed, and sieved to 60-100 mesh. The hydrophilic SiO2 is compressed into tablets, crushed, and sieved to obtain particles with a particle size of 60-100 mesh. The catalyst and the physical desiccant are mixed in a mass ratio of 1.0:1 to obtain particles with a particle size of 60-100 mesh, sealed, and placed in a desiccator for later use.

[0037] The catalyst prepared in this embodiment was applied to the synthesis of DMC from CO2 and methanol. The catalytic reaction was carried out in a fixed-bed reactor. The CO2 flow rate was controlled by a mass flow meter at 100 mL / min, and the methanol flow rate was controlled by a horizontal flow pump at a methanol liquid hourly space velocity (LHSV) of 8 h⁻¹. -1After the catalyst was loaded into the reaction tube, 10% H2 / N2 was first introduced and the reaction was reduced at 240℃ for 5 hours. After the reduction was completed, nitrogen was introduced to cool the reactor. Then, CO2 and methanol were switched and preheated in a 140℃ preheating furnace before entering the reactor. The reaction temperature was 160℃ and the pressure was 4MPa. The reaction lasted for 300 hours. All reaction products at 1 hour, 10 hours, 30 hours, 50 hours, 100 hours and 300 hours were directly introduced into the gas chromatograph for online analysis through the heat-insulated pipeline. The catalyst and reaction conditions are listed in Table 1, the reaction results are listed in Table 2, and the long-term stability test results are listed in Table 3.

[0038]

[0039] It should be noted that, although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A heteropolyacid-modified CuNiCeZrO X The preparation method of the catalyst, wherein CuNiCeZrO X The catalyst has a molar ratio of metal elements (calculated as oxides) of Ce:Zr:Ni:Cu = (10~5):(7~4):(3~1):1, characterized in that: The preparation method includes the following steps: S1: CuNiCeZrO X Preparation of composite oxide catalysts; Using cerium nitrate, zirconium nitrate, nickel nitrate, and copper nitrate as active components, the above active components and template agent are dissolved in water to obtain solution A; an alkaline aqueous solution is prepared to obtain solution B; Solution B was slowly added dropwise to solution A under continuous stirring to obtain a mixed solution. The temperature of the mixed solution was raised to 70-90℃ and maintained for 3-6 hours before filtration. The filter cake was washed, dried, and then calcined in a muffle furnace at 500-700℃ to obtain CuNiCeZrO. X Composite oxide catalyst powder; S2: Heteropolyacid modified CuNiCeZrO X Composite oxide catalysts; The heteropolyacid solution was slowly added dropwise to the CuNiCeZrO using an equal-volume impregnation method. X The composite oxide catalyst powder was ultrasonicated, allowed to stand, dried, and then calcined in a muffle furnace at 400-500℃ to obtain the heteropolyacid-modified CuNiCeZrO. X Composite oxidation catalyst; S3: Physical desiccant coupled with CuNiCeZrO X Composite oxidation catalyst; The heteropolyacid-modified CuNiCeZrO X The composite oxide catalyst is compressed into tablets, crushed, and sieved to obtain catalyst particles. A physical desiccant tablet is compressed, crushed, or directly crushed and sieved to obtain physical desiccant particles. The catalyst particles and the physical desiccant particles are mixed to obtain the heteropolyacid-modified CuNiCeZrO. X catalyst.

2. The heteropolyacid-modified CuNiCeZrO according to claim 1 X A method for preparing a catalyst, characterized in that: The template agent is one of hexadecyltrimethylammonium bromide, tetraethylammonium hydroxide, or tetrapropylammonium hydroxide, and the molar ratio of the template agent to the active component is 0.3~1.0:

1.

3. The heteropolyacid-modified CuNiCeZrO according to claim 1 X A method for preparing a catalyst, characterized in that: The molar concentration of solution A is 0.1~1.0 mol / L.

4. The heteropolyacid-modified CuNiCeZrO according to claim 1 X A method for preparing a catalyst, characterized in that: Solution B is one of NaOH, ammonia, NaCO3, NaHCO3, or urea solution, with a mass fraction of 10% to 40%.

5. The heteropolyacid-modified CuNiCeZrO according to claim 1 X A method for preparing a catalyst, characterized in that: Solution B is slowly added dropwise to solution A, which is continuously stirred, while the temperature is maintained at 40~60℃.

6. The heteropolyacid-modified CuNiCeZrO according to claim 1 X A method for preparing a catalyst, characterized in that: The heteropolyacid is one of phosphoric acid, molybdenum phosphoric acid, tungstic phosphoric acid or tungstic silicate, with a mass fraction of 60% to 90%.

7. The heteropolyacid-modified CuNiCeZrO according to claim 1 X A method for preparing a catalyst, characterized in that: In step S1, the heating rate of the muffle furnace is 2~5℃ / min, and the calcination time is 5~10h.

8. The heteropolyacid-modified CuNiCeZrO according to claim 1 X A method for preparing a catalyst, characterized in that: The physical absorbent is one of 5A molecular sieve, 10X molecular sieve, hydrophilic SiO2, montmorillonite, and silica gel.

9. The heteropolyacid-modified CuNiCeZrO according to claim 1 X A method for preparing a catalyst, characterized in that: The catalyst particles and the physical absorbent particles have a particle size of 60-100 mesh.

10. The heteropolyacid-modified CuNiCeZrO according to claim 1 X A method for preparing a catalyst, characterized in that: The mass ratio of the catalyst particles to the physical desiccant particles is 0.5 to 2.

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