Process for the preparation of a cuazrxc eyoz catalyst modification

Abstract

This invention relates to the field of dimethyl carbonate synthesis technology, and discloses a Cu a Zr x Ce y O z A catalyst modification preparation method includes the following steps: S01: Weigh cerium salt, zirconium salt, and copper salt, and prepare an active component solution C1 using an organic alcohol as a solvent; weigh sodium phosphate, sodium tetraborate, urea, or thiourea, and prepare an auxiliary agent solution C2 using water as a solvent; weigh NaOH or sodium carbonate, and prepare a precipitant solution C3 using water as a solvent; S02: Slowly add solution C2 dropwise to solution C1 while stirring at 40℃~60℃, and maintain the temperature; then, at 60℃~85℃ and pH maintained at 8.0~10, slowly add solution C3 to the above mixed solution of C1 and C2, and continue stirring while maintaining the temperature, with reflux throughout the process; finally, crystallize and age the precipitate, wash until neutral, dry, and calcine in a muffle furnace. This invention improves the catalytic activity of methanol and CO2 to DMC production by adjusting the dielectric environment of the mixed solvent with an organic alcohol and modifying the metal oxide catalyst with heteroatoms such as N, S, P, and B.

Description

Technical Field

[0001] This invention belongs to the field of dimethyl carbonate synthesis technology, specifically relating to a Cu a Zr x Ce y O z Catalyst modification and preparation methods. Background Technology

[0002] Dimethyl carbonate (DMC) is an important environmentally friendly chemical raw material with wide applications in the chemical industry. Firstly, DMC serves as an excellent methylating and methoxycarbonylating agent, replacing highly corrosive and toxic dimethyl sulfate (DMS), halomethanes, and phosgene, thereby significantly reducing environmental risks and safety hazards in the production process. Secondly, due to its high octane number (RON 115) and high oxygen content (53% by mass), DMC is a highly efficient fuel additive, effectively improving engine combustion performance and reducing pollutant emissions. Furthermore, DMC is a key solvent component in lithium-ion battery electrolytes, crucial for battery performance and safety.

[0003] Currently, the main industrial synthesis methods for DMC include the methanol-phosgene method and the methanol oxidative carbonylation method. However, these traditional processes have significant drawbacks. The former relies on highly toxic phosgene as a raw material, posing a serious threat to the environment and operators; the latter involves a mixture of carbon monoxide and oxygen, posing flammable and explosive risks, and typically requires high production costs. Therefore, developing a greener, safer, and more economical DMC synthesis route has become a research focus in this field.

[0004] From the perspective of atom economy and environmental friendliness in chemical conversion, the direct synthesis of DMC from carbon dioxide and methanol is considered the most promising alternative route. This method not only effectively utilizes the greenhouse gas CO2 but also aligns with the development trend of green chemistry. Nevertheless, this reaction route is severely limited thermodynamically, resulting in extremely low equilibrium conversion rates under conventional conditions, hindering industrial application. Therefore, designing and developing highly active and selective catalytic systems to effectively overcome thermodynamic bottlenecks under mild conditions is crucial for achieving a technological breakthrough.

[0005] Among numerous catalysts, cerium dioxide (CeO2)-based catalysts have attracted considerable attention due to their unique redox properties, abundant surface oxygen vacancies, and excellent catalytic activity. Studies have shown that oxygen vacancies on the CeO2 surface and their adjacent low-valence Ce3+ ions play a decisive role in the adsorption and activation of CO2 molecules, serving as key active sites for the non-reductive conversion of CO2. By doping the CeO2 lattice with transition metals (such as Zr, Cu, Fe, Co, Mn, etc.) or rare earth metals (such as La, Pr, Sm, Gd, etc.), its electronic structure can be effectively modulated, promoting the formation of oxygen vacancies and stabilizing Ce3+ species, thereby significantly improving catalytic activity and DMC yield.

[0006] Despite the great potential shown by CeO2-based catalysts, existing technologies still have shortcomings. Chinese invention patent CN112823879A discloses a method for preparing M by co-precipitation. x Ce 1-x O y The catalyst, where M is a metallic element such as Mn, Cu, or Ti, uses pure water as a solvent. Under reaction conditions of 140℃ and 3MPa, the highest yield of DMC is less than 18%. Another Chinese invention patent, CN110479236A, discloses a composite catalyst with Ce, La, and Zr oxides as active components. It is also prepared using an aqueous co-precipitation method, but under conditions of 130℃ and 5MPa, the DMC yield is only 15%.

[0007] Analysis revealed that the traditional aqueous coprecipitation method commonly used in the aforementioned existing technologies is one of the bottlenecks limiting further improvement in catalyst performance. During precipitation in water, a solvent with a high dielectric constant, the hydrolysis and nucleation rates of metal ions are extremely rapid, easily leading to uncontrolled agglomeration of the generated nanocrystals, forming large, unevenly distributed secondary particles. This severe agglomeration significantly reduces the specific surface area of ​​the catalyst and encapsulates a large number of active sites within the catalyst bulk phase, preventing effective contact between these sites and reactant molecules. Therefore, insufficient exposure of active sites ultimately results in low apparent activity of the catalyst, making it difficult to meet the demands of industrial-scale DMC production. There is an urgent need in this field to develop a new catalyst preparation method that can effectively suppress particle agglomeration during the preparation of CeO2-based catalysts, thereby obtaining catalysts with high specific surface area and fully exposed active sites, significantly improving the reaction yield of DMC directly synthesized from CO2 and methanol. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a Cu a Zr x Cey O z A catalyst modification preparation method was developed, which achieved nanoscale Cu by adjusting the dielectric environment of a mixed solvent using an organic solvent. a Zr x Ce y O z The controllable synthesis of metal oxide catalysts improves the accumulation and agglomeration of catalyst particles during the precipitation process of traditional oxide catalysts, regulates the catalyst structure, and increases the active specific surface area. Simultaneously, doping with heteroatoms such as N, S, P, and B improves the physicochemical properties of metal oxides, increasing oxygen vacancies and Ce content on the catalyst surface. 3+ Concentration is increased, thereby enhancing catalytic activity. Modification methods such as solvent adjustment and heteroatom doping provide a cost-effective optimization approach for the synthesis of DMC catalysts, achieving high methanol conversion and DMC yield without the use of dehydrating agents.

[0009] To achieve the goal of the above-mentioned optimized method for improving methanol conversion and DMC yield without using a dehydrating agent, the present invention provides the following technical solution:

[0010] 2. A Cu a Zr x Ce y O z Catalyst modification preparation method, wherein the Cu a Zr x Ce y O z The molar ratio of Cu, Zr, and Ce oxides in the catalyst is a:x:y = 1:1~5:5~10, and the modified preparation method includes the following steps:

[0011] S01: Preparation of precursor solution

[0012] Weigh out cerium, zirconium, and copper salts soluble in organic alcohols, and prepare active component solution C1 using organic alcohols as solvents; weigh out sodium phosphate, sodium tetraborate, urea, or thiourea, and prepare auxiliary agent solution C2 using water as solvents; weigh out NaOH, NaCO3, or NaHCO3, and prepare precipitant solution C3 using water as solvents.

[0013] SO2: Preparation of catalysts with solvent conditioning and heteroatom modification

[0014] Solution C2 was slowly added dropwise to solution C1 while stirring at 40℃~60℃, and the mixture was kept warm and stirred. Then, solution C3 was slowly added to the mixture of C1 and C2 at 60℃~85℃ and pH maintained at 8.0~10, while continuing to stir and maintain the temperature. The entire process was carried out under reflux. Finally, the precipitate was crystallized and aged, washed until neutral, dried, and calcined in a muffle furnace to obtain the Cu. a Zr x Ce y O z catalyst.

[0015] Preferably, the organic alcohol is one or more of anhydrous ethanol, n-propanol, ethylene glycol, glycerol, or n-butanol.

[0016] Preferably, in step S01: the cerium salt, zirconium salt and copper salt soluble in organic alcohols are respectively: cerium nitrate, zirconium nitrate and copper nitrate.

[0017] Preferably, the molar concentration of the active component solution C1 is 0.5~2.0 mol / L, the molar concentration of the auxiliary agent solution C2 is 0.1~0.8 mol / L, the mass fraction of the precipitant solution C3 is 20%~40%wt, and the volume ratio of the active component solution C1: auxiliary agent solution C2: precipitant solution C3 is 5:1:2.

[0018] Preferably, in step S02: the C2 solution is slowly added dropwise to the C1 solution while stirring at 40℃~60℃, and the stirring and heat preservation time is 1~3h.

[0019] Preferably, in step S02: under the conditions of 60℃~85℃ and pH maintained at 8.0~10, the C3 solution is slowly added to the above mixed solution of C1 and C2, and the duration of continued heating and stirring is 2~4h.

[0020] Preferably, in step S02, the temperature for aging the precipitate through crystallization is 90~120℃.

[0021] Preferably, in step S02, the time for aging the precipitate through crystallization is 8 to 24 hours.

[0022] Preferably, in step S02, the drying process conditions are: drying at 100~120℃ for 5-8 hours.

[0023] Preferably, in step S02, the heating rate of the muffle furnace during roasting is 1.5~3.5℃ / min.

[0024] Preferably, in step S02, the calcination process conditions in the muffle furnace are: calcination at 450~700℃ for 4~9 hours.

[0025] Compared with the prior art, the present invention provides a Cu a Zr x Ce y O z The catalyst modification preparation method has the following beneficial effects:

[0026] Firstly: the Cu of the present invention a Zr x Ce y O z A catalyst modification preparation method was developed, which achieved nanoscale Cu by adjusting the dielectric environment of a mixed solvent using an organic alcohol solvent. a Zr x Ce y O z Controllable synthesis of metal oxides increases DMC yield by more than 10%.

[0027] Secondly, this invention improves the performance of Cu by modifying metal oxide catalysts with heteroatoms such as N, S, P, and B. a Zr x Ce y O z oxygen vacancies and Ce in the catalyst 3+ Concentration adjusts the pH of the catalyst and regulates its structure, increasing the specific surface area of ​​the catalyst, which facilitates the exposure of active sites and improves catalytic activity.

[0028] Thirdly, dehydrating agents are usually expensive and not environmentally friendly. This invention does not require the use of dehydrating agents. It achieves efficient catalytic conversion of methanol and CO2 through solvent adjustment and heteroatom modification, which is in line with the concept of "green chemistry" and has the advantages of being both environmentally friendly and economical. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1

[0031] A Cu1 / Zr1Ce5O 13 The catalyst modification method, specifically the following steps:

[0032] S01: Preparation of precursor solution

[0033] Weigh 232.95 g of cerium nitrate, 48.46 g of zirconium nitrate, and 26.79 g of copper nitrate, dissolve them in anhydrous ethanol, and dilute to volume in a 500 mL volumetric flask. This solution is designated as active component solution C1 (molar concentration 2.0 mol / L). Dissolve 1.64 g of sodium phosphate in water and dilute to volume in a 100 mL volumetric flask. This solution is designated as auxiliary agent solution C2 (molar concentration 0.1 mol / L). Dissolve 49.8 g of NaOH in water and dilute to volume in a 250 mL volumetric flask. This solution is designated as precipitant solution C3 (mass fraction 20%). Solutions C1, C2, and C3 are referred to as catalyst precursor solutions.

[0034] SO2: Preparation of catalysts with solvent conditioning and heteroatom modification

[0035] 500 mL of C1 solution was placed in a water bath. While magnetically stirring at 40 °C, 100 mL of C2 solution was slowly added to solution C1 using a dropper. After the addition was complete, heating and stirring continued for 3 hours. Subsequently, 200 mL of C3 solution was slowly added to the above solution using a peristaltic pump, maintaining the temperature at approximately 60 °C and the pH at approximately 8.0. After the addition was complete, heating and stirring continued for 4 hours. The entire process was carried out using reflux condensation. After completion, the precipitate was placed in a hydrothermal reactor for crystallization aging at 90 °C for 24 hours. It was then washed until neutral by filtration, dried in an oven at 100 °C for 8 hours, and finally calcined in a muffle furnace at 450 °C for 9 hours at a heating rate of 1.5 °C / min to obtain Cu1 / Zr1Ce5O. 13 catalyst.

[0036] Cu1 / Zr1Ce5O will be obtained 13 The catalyst was used in the synthesis of DMC in a fixed-bed reactor. First, reduction was performed at 200℃ and 0.5 MPa using a 10% H2 / N2 gas atmosphere for 12 h. After reduction, N2 was introduced to cool the reactor. Then, the flow rate of CO2 was switched to 10 mL / min and the liquid hourly space velocity (LHSV) to 0.5 h⁻¹. -1 Methanol is preheated in a 140℃ preheating furnace before entering the reactor for reaction. The reaction temperature is 120℃ and the pressure is 6MPa. The reaction products are condensed in a 0℃ condenser, and the liquid samples are sent to the gas chromatograph for offline analysis. The non-condensable products are sent directly to the gas chromatograph for online analysis through an insulated pipeline.

[0037] Example 2

[0038] A Cu1 / Zr2Ce6O 17 The catalyst modification method, specifically the following steps:

[0039] S01: Preparation of precursor solution

[0040] Weigh 173.94 g of cerium nitrate, 60.31 g of zirconium nitrate, and 16.67 g of copper nitrate, dissolve them in n-propanol, and dilute to volume in a 500 mL volumetric flask. This solution is designated as active component solution C1 (molar concentration 1.6 mol / L). Dissolve 3.28 g of sodium phosphate in water and dilute to volume in a 100 mL volumetric flask. This solution is designated as auxiliary agent solution C2 (molar concentration 0.2 mol / L). Dissolve 62.5 g of NaOH in water and dilute to volume in a 250 mL volumetric flask. This solution is designated as precipitant solution C3 (mass fraction 25%). Solutions C1, C2, and C3 are referred to as catalyst precursor solutions.

[0041] SO2: Preparation of catalysts with solvent conditioning and heteroatom modification

[0042] 500 mL of C1 solution was placed in a water bath. While magnetically stirring at 45 °C, 100 mL of C2 solution was slowly added to solution C1 using a dropper. After the addition was complete, heating and stirring continued for 2.5 h. Subsequently, 200 mL of C3 solution was slowly added to the above solution using a peristaltic pump, maintaining the temperature at approximately 65 °C and the pH at approximately 8.5. After the addition was complete, heating and stirring continued for 3.5 h. The entire process was carried out using reflux condensation. After completion, the precipitate was placed in a hydrothermal reactor and aged at 95 °C for 22 h. It was then washed until neutral by filtration, dried in an oven at 105 °C for 7 h, and finally calcined in a muffle furnace at 500 °C for 8 h at a heating rate of 2.0 °C / min to obtain Cu1 / Zr2Ce6O. 17 catalyst.

[0043] Cu1 / Zr2Ce6O was obtained 17 The catalyst was used in the synthesis of DMC in a fixed-bed reactor. The reaction was first carried out at 220℃ and 0.5 MPa with a 10% H2 / N2 gas flow rate for 11 h. After reduction, N2 was introduced to cool the reactor. Then, the flow rate of CO2 was switched to 20 mL / min and the liquid hourly space velocity (LHSV) was set to 2 h⁻¹. -1 Methanol is preheated in a 150℃ preheating furnace before entering the reactor for reaction. The reaction temperature is 130℃ and the pressure is 5.5MPa. The reaction products are condensed in a 0℃ condenser, and the liquid sample is then analyzed offline by gas chromatography. The non-condensable products are directly analyzed online by gas chromatography through an insulated pipeline.

[0044] Example 3

[0045] A Cu1 / Zr3Ce7O 21 The catalyst modification method, specifically the following steps:

[0046] S01: Preparation of precursor solution

[0047] Weigh 145.27 g of cerium nitrate, 64.76 g of zirconium nitrate, and 11.94 g of copper nitrate, dissolve them in ethylene glycol, and dilute to volume in a 500 mL volumetric flask. This solution is designated as active component solution C1 (molar concentration 1.4 mol / L). Dissolve 6.03 g of sodium tetraborate in water and dilute to volume in a 100 mL volumetric flask. This solution is designated as auxiliary agent solution C2 (molar concentration 0.3 mol / L). Dissolve 75.1 g of NaCO3 in water and dilute to volume in a 250 mL volumetric flask. This solution is designated as precipitant solution C3 (mass fraction 30%). Solutions C1, C2, and C3 are referred to as catalyst precursor solutions.

[0048] SO2: Preparation of catalysts with solvent conditioning and heteroatom modification

[0049] 500 mL of C1 solution was placed in a water bath. While magnetically stirring at 48 °C, 100 mL of C2 solution was slowly added to solution C1 using a dropper. After the addition was complete, heating and stirring continued for 2.1 h. Subsequently, 200 mL of C3 solution was slowly added to the above solution using a peristaltic pump, maintaining the temperature at approximately 68 °C and the pH at approximately 8.7. After the addition was complete, heating and stirring continued for 3.2 h. The entire process was carried out using reflux condensation. After completion, the precipitate was placed in a hydrothermal reactor for crystallization aging at 98 °C for 20 h. It was then washed until neutral by filtration, dried in an oven at 110 °C for 6 h, and finally calcined in a muffle furnace at 550 °C for 7 h at a heating rate of 2.5 °C / min to obtain Cu1 / Zr3Ce7O. 21 catalyst.

[0050] The resulting Cu1 / Zr3Ce7O 21 The catalyst was used in the synthesis of DMC in a fixed-bed reactor. The reaction was first carried out at 240℃ and 0.5 MPa with a 10% H2 / N2 gas flow rate for 10 h. After reduction, N2 was introduced to cool the reactor. Then, the flow rate of CO2 was switched to 30 mL / min and the liquid hourly space velocity (LHSV) was set to 6 h⁻¹. -1 Methanol is preheated in a 160℃ preheating furnace before entering the reactor for reaction. The reaction temperature is 140℃ and the pressure is 5MPa. The reaction products are condensed in a 0℃ condenser, and the liquid samples are sent to the gas chromatograph for offline analysis. The non-condensable products are sent directly to the gas chromatograph for online analysis through an insulated pipeline.

[0051] Example 4

[0052] A Cu1 / Zr4Ce8O 25The catalyst modification method, specifically the following steps:

[0053] S01: Preparation of precursor solution

[0054] Weigh 100.35 g of cerium nitrate, 52.19 g of zirconium nitrate, and 7.21 g of copper nitrate, dissolve them in glycerol, and dilute to volume in a 500 mL volumetric flask. This solution is designated as active component solution C1 (molar concentration 1.0 mol / L). Dissolve 3.01 g of urea in water and dilute to volume in a 100 mL volumetric flask. This solution is designated as auxiliary agent solution C2 (molar concentration 0.5 mol / L). Dissolve 87.5 g of NaCO3 in water and dilute to volume in a 250 mL volumetric flask. This solution is designated as precipitant solution C3 (mass fraction 35%). Solutions C1, C2, and C3 are referred to as catalyst precursor solutions.

[0055] SO2: Preparation of catalysts with solvent conditioning and heteroatom modification

[0056] 500 mL of C1 solution was placed in a water bath. While magnetically stirring at 50 °C, 100 mL of C2 solution was slowly added to solution C1 using a dropper. After the addition was complete, heating and stirring continued for 1.8 h. Subsequently, 200 mL of C3 solution was slowly added to the above solution using a peristaltic pump, maintaining the temperature at approximately 75 °C and the pH at approximately 9.0. After the addition was complete, heating and stirring continued for 2.5 h. The entire process was carried out using reflux condensation. After completion, the precipitate was placed in a hydrothermal reactor and crystallized at 105 °C for 16 h. It was then filtered and washed until neutral, dried in an oven at 115 °C for 5.5 h, and finally calcined in a muffle furnace at 600 °C for 6 h at a heating rate of 3 °C / min to obtain Cu1 / Zr4Ce8O. 25 catalyst.

[0057] This will yield Cu1 / Zr4Ce8O 25 The catalyst was used in the synthesis of DMC in a fixed-bed reactor. The reaction was first carried out at 260℃ and 0.5 MPa with a 10% H2 / N2 gas flow rate for 9 h. After reduction, N2 was introduced to cool the reactor. Then, the flow rate of CO2 was switched at 40 mL / min and the liquid hourly space velocity (LHSV) was set to 15 h⁻¹. -1 Methanol is preheated in a 170℃ preheating furnace before entering the reactor for reaction. The reaction temperature is 150℃ and the pressure is 4.5MPa. The reaction products are condensed in a 0℃ condenser, and the liquid samples are then analyzed offline by gas chromatography. The non-condensable products are directly analyzed online by gas chromatography through an insulated pipeline.

[0058] Example 5

[0059] A Cu1 / Zr5Ce10 O 31 The catalyst modification method, specifically the following steps:

[0060] S01: Preparation of precursor solution

[0061] Weigh 50.96 g of cerium nitrate, 2651 g of zirconium nitrate, and 2.93 g of copper nitrate, dissolve them in n-butanol, and dilute to volume in a 500 mL volumetric flask. This solution is designated as active component solution C1 (molar concentration 0.5 mol / L). Dissolve 6.09 g of thiourea in water and dilute to volume in a 100 mL volumetric flask. This solution is designated as auxiliary agent solution C2 (molar concentration 0.8 mol / L). Dissolve 99.8 g of NaHCO3 in water and dilute to volume in a 250 mL volumetric flask. This solution is designated as precipitant solution C3 (mass fraction 40%). Solutions C1, C2, and C3 are referred to as catalyst precursor solutions.

[0062] SO2: Preparation of catalysts with solvent conditioning and heteroatom modification

[0063] 500 mL of C1 solution was placed in a water bath. While magnetically stirring at 55 °C, 100 mL of C2 solution was slowly added to solution C1 using a dropper. After the addition was complete, heating and stirring continued for 1.5 h. Subsequently, 200 mL of C3 solution was slowly added to the above solution using a peristaltic pump, maintaining the temperature at approximately 80 °C and the pH at approximately 9.5. After the addition was complete, heating and stirring continued for 2.2 h. The entire process was carried out using reflux condensation. After completion, the precipitate was placed in a hydrothermal reactor and crystallized at 110 °C for 14 h. It was then filtered and washed until neutral, dried in an oven at 120 °C for 5 h, and finally calcined in a muffle furnace at 650 °C for 5 h at a heating rate of 3.2 °C / min to obtain Cu1 / Zr5Ce. 10 O 31 catalyst.

[0064] The obtained Cu1 / Zr5Ce 10 O 31 The catalyst was used in the synthesis of DMC in a fixed-bed reactor. The reaction was first carried out at 280℃ and 0.5 MPa with a 10% H2 / N2 gas flow rate for 7 h. After reduction, N2 was introduced to cool the reactor. Then, the flow rate of CO2 was switched to 60 mL / min and the liquid hourly space velocity (LHSV) was set to 30 h⁻¹. -1 Methanol is preheated in a 180℃ preheating furnace before entering the reactor for reaction. The reaction temperature is 160℃ and the pressure is 4.0MPa. The reaction products are condensed in a 0℃ condenser, and the liquid sample is sent to the gas chromatograph for offline analysis. The non-condensable products are sent directly to the gas chromatograph for online analysis through an insulated pipeline.

[0065] Example 6

[0066] A Cu1 / Zr3Ce9O 31 The catalyst modification method, specifically the following steps:

[0067] S01: Preparation of precursor solution

[0068] Weigh 135.47 g of cerium nitrate, 46.92 g of zirconium nitrate, and 8.66 g of copper nitrate, dissolve them in ethylene glycol, and dilute to volume in a 500 mL volumetric flask. Record this as active component solution C1 (molar concentration 1.2 mol / L). Dissolve 3.61 g of urea in water and dilute to volume in a 100 mL volumetric flask. Record this as auxiliary agent solution C2 (molar concentration 0.6 mol / L). Dissolve 60.1 g of NaOH in water and dilute to volume in a 250 mL volumetric flask. Record this as precipitant.

[0069] Solution C3 (mass fraction 24%). Solutions C1, C2, and C3 are called catalyst precursor solutions.

[0070] SO2: Preparation of catalysts with solvent conditioning and heteroatom modification

[0071] 500 mL of C1 solution was placed in a water bath. While magnetically stirring at 60 °C, 100 mL of C2 solution was slowly added to solution C1 using a dropper. After the addition was complete, heating and stirring continued for 1 hour. Subsequently, 200 mL of C3 solution was slowly added to the above solution using a peristaltic pump, maintaining the temperature at approximately 85 °C and the pH at approximately 10. After the addition was complete, heating and stirring continued for 2 hours. The entire process was carried out using reflux condensation. After completion, the precipitate was placed in a hydrothermal reactor for crystallization aging at 120 °C for 8 hours. It was then filtered and washed until neutral, dried in an oven at 120 °C for 5 hours, and finally calcined in a muffle furnace at 700 °C for 4 hours at a heating rate of 3.5 °C / min to obtain Cu1 / Zr3Ce9O. 31 catalyst.

[0072] The obtained Cu1 / Zr3Ce9O 31 The catalyst was used in the synthesis of DMC in a fixed-bed reactor. The reaction was first carried out at 300℃ and 0.5 MPa with a 10% H2 / N2 gas flow rate for 5 h. After reduction, N2 was introduced to cool the reactor. Then, the flow rate of CO2 was switched to 100 mL / min and the liquid hourly space velocity (LHSV) was set to 60 h⁻¹. -1Methanol is preheated in a 200℃ preheating furnace before entering the reactor for reaction. The reaction temperature is 180℃ and the pressure is 2.0MPa. The reaction products are condensed in a 0℃ condenser, and the liquid sample is sent to the gas chromatograph for offline analysis. The non-condensable products are sent directly to the gas chromatograph for online analysis through an insulated pipeline.

[0073] Example 7

[0074] A Cu1 / Zr2Ce8O 21 The catalyst modification method, specifically the following steps:

[0075] S01: Preparation of precursor solution

[0076] Weigh 118.59 g of cerium nitrate, 30.84 g of zirconium nitrate, and 8.53 g of copper nitrate, dissolve them in glycerol, and dilute to volume in a 500 mL volumetric flask. This solution is designated as active component solution C1 (molar concentration 1.0 mol / L). Dissolve 10.06 g of sodium tetraborate in water and dilute to volume in a 100 mL volumetric flask. This solution is designated as auxiliary agent solution C2 (molar concentration 0.5 mol / L). Dissolve 79.9 g of NaCO3 in water and dilute to volume in a 250 mL volumetric flask. This solution is designated as precipitant solution C3 (mass fraction 32%). Solutions C1, C2, and C3 are referred to as catalyst precursor solutions.

[0077] SO2: Preparation of catalysts with solvent conditioning and heteroatom modification

[0078] 500 mL of C1 solution was placed in a water bath. While magnetically stirring at 50 °C, 100 mL of C2 solution was slowly added to solution C1 using a dropper. After the addition was complete, heating and stirring continued for 2 hours. Subsequently, 200 mL of C3 solution was slowly added to the above solution using a peristaltic pump, maintaining the temperature at approximately 75 °C and the pH at approximately 9.0. After the addition was complete, heating and stirring continued for 3 hours. The entire process was carried out using reflux condensation. After completion, the precipitate was placed in a hydrothermal reactor and crystallized at 110 °C for 15 hours. It was then filtered and washed until neutral, dried in an oven at 110 °C for 6 hours, and finally calcined in a muffle furnace at 600 °C for 6 hours at a heating rate of 3.0 °C / min to obtain Cu1 / Zr2Ce8O. 21 catalyst.

[0079] The obtained Cu1 / Zr2Ce8O 21The catalyst was used in the synthesis of DMC in a fixed-bed reactor. The reaction was first carried out at 240℃ and 0.5 MPa with a 10% H2 / N2 gas flow for 8 hours. After reduction, N2 was introduced to cool the reactor. Then, the flow rate of CO2 was switched to 80 mL / min and the liquid hourly space velocity (LHSV) was set to 30 h⁻¹. -1 Methanol is preheated in a 170℃ preheating furnace before entering the reactor for reaction. The reaction temperature is 150℃ and the pressure is 4.0MPa. The reaction products are condensed in a 0℃ condenser, and the liquid sample is then analyzed offline by gas chromatography. The non-condensable products are directly analyzed online by gas chromatography through an insulated pipeline.

[0080] Example 8

[0081] The effect of using deionized water as a solvent on the reaction activity was compared, and the specific steps are as follows:

[0082] S01: Preparation of precursor solution

[0083] Weigh 118.61g of cerium nitrate, 30.79g of zirconium nitrate and 8.58g of copper nitrate, dissolve them in deionized water, and follow the same procedure as in Example 7.

[0084] SO2: Preparation of catalysts with solvent conditioning and heteroatom modification

[0085] Same as Example 7.

[0086] The obtained catalyst was used in the synthesis of DMC, and the specific steps were the same as in Example 7.

[0087] Example 9

[0088] The effects of not using heteroatom doping modification on the reaction are compared, and the specific steps are as follows:

[0089] S01: Preparation of precursor solution

[0090] Weigh 118.53 g of cerium nitrate, 30.88 g of zirconium nitrate, and 8.57 g of copper nitrate, dissolve them in glycerol, and dilute to volume in a 500 mL volumetric flask. This solution is designated as active component solution C1 (molar concentration 1.0 mol / L). Dissolve 80.3 g of NaCO3 in water and dilute to volume in a 250 mL volumetric flask. This solution is designated as precipitant solution C2 (mass fraction 32%). Solutions C1 and C2 are referred to as catalyst precursor solutions.

[0091] SO2: Preparation of catalysts with solvent conditioning and heteroatom modification

[0092] Place 500 mL of C1 solution in a water bath, and slowly add 200 mL of C2 solution to the above solution using a peristaltic pump. The rest is the same as in Example 7.

[0093] The obtained catalyst was used in the synthesis of DMC, and the specific steps were the same as in Example 7.

[0094] reaction results

[0095] Table 1 Catalyst modification optimization and reaction conditions

[0096] Serial Number catalyst Solvent medium heteroatom reagents Reaction conditions Example 1 <![CDATA[Cu1 / Zr1Ce5O 13 ]]> Anhydrous ethanol Sodium phosphate (P) <![CDATA[Reduction at 200 °C, reaction at 120 °C and 6 MPa, methanol space velocity 0.5 h -1 > Example 2 <![CDATA[Cu1 / Zr2Ce6O 17 ]]> n-Propanol Sodium phosphate (P) <![CDATA[Reduction at 220 °C, reaction at 130 °C and 5.5 MPa, methanol space velocity 2 h -1 > Example 3 <![CDATA[Cu1 / Zr3Ce7O 21 ]]> Ethylene glycol Sodium tetraborate (B) <![CDATA[Reduction at 240 °C, reaction at 140 °C and 5 MPa, methanol space velocity 6 h -1 > Example 4 <![CDATA[Cu1 / Zr4Ce8O 25 ]]> Glycerol Urea (N) <![CDATA[Reduction at 260 °C, reaction at 150 °C and 4.5 MPa, methanol space velocity 15 h -1 > Example 5 <![CDATA[Cu1 / Zr5Ce 10 THE 31 ]]> n-Butanol Thiourea (S) <![CDATA[Reduction at 280 °C, reaction at 160 °C and 4 MPa, methanol space velocity 30 h -1 > Example 6 <![CDATA[Cu1 / Zr3Ce9O 31 ]]> Ethylene glycol Urea (N) <![CDATA[Reduction at 300 °C, reaction at 180 °C and 2 MPa, methanol space velocity 60 h -1 > Example 7 <![CDATA[Cu1 / Zr2Ce8O 21 ]]> Glycerol Sodium tetraborate (B) <![CDATA[Reduction at 240 °C, reaction at 150 °C and 4 MPa, methanol space velocity 30 h -1 > Example 8 <![CDATA[Cu1 / Zr2Ce8O 21 ]]> Deionized water Sodium tetraborate (B) <![CDATA[Reduction at 240 °C, reaction at 150 °C and 4 MPa, methanol space velocity 30 h -1 > Example 9 <![CDATA[Cu1 / Zr2Ce8O 21 ]]> Glycerol No heteroatoms <![CDATA[Reduction at 240 °C, reaction at 150 °C and 4 MPa, methanol space velocity 30 h -1 >

[0097] Table 2 Reaction Results

[0098] Serial Number catalyst Methanol conversion rate DMC Selectivity Dimethyl ether selectivity Example 1 <![CDATA[Cu1 / Zr1Ce5O 13 ]]> 47.8% 97.2% 2.8% Example 2 <![CDATA[Cu1 / Zr2Ce6O 17 ]]> 46. 1% 98.0% 2.0% Example 3 <![CDATA[Cu1 / Zr3Ce7O 21 ]]> 46.8% 97.7% 2.3% Example 4 <![CDATA[Cu1 / Zr4Ce8O 25 ]]> 49.2% 98.5% 1.5% Example 5 <![CDATA[Cu1 / Zr5Ce 10 THE 31 ]]> 48.4% 99.3% 0.7% Example 6 <![CDATA[Cu1 / Zr3Ce9O 31 ]]> 47. 1% 98.4% 1.6% Example 7 <![CDATA[Cu1 / Zr2Ce8O 21 ]]> 50.2% 98.9% 1. 1% Example 8 <![CDATA[Cu1 / Zr2Ce8O 21 ]]> 38.3% 98. 1% 1.9% Example 9 <![CDATA[Cu1 / Zr2Ce8O 21 ]]> 41.2% 97.2% 2.8%

[0099] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one…" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0100] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A Cu a Zr x Ce y O z The catalyst modification preparation method is characterized by: Cu prepared by the modified preparation method a Zr x Ce y O z The molar ratio of Cu, Zr, and Ce oxides in the catalyst is a:x:y = 1:1~5:5~10, and the modified preparation method includes the following steps: S01: Preparation of precursor solution Weigh out cerium, zirconium, and copper salts soluble in organic alcohols, and prepare active component solution C1 using organic alcohols as solvents; weigh out sodium phosphate, sodium tetraborate, urea, or thiourea, and prepare auxiliary agent solution C2 using water as solvents; weigh out NaOH, NaCO3, or NaHCO3, and prepare precipitant solution C3 using water as solvents. SO2: Preparation of catalysts with solvent conditioning and heteroatom modification Solution C2 was slowly added dropwise to solution C1 while stirring at 40℃~60℃, and the mixture was kept warm and stirred. Then, solution C3 was slowly added to the mixture of C1 and C2 at 60℃~85℃ and pH maintained at 8.0~10, while continuing to stir and maintain the temperature. The entire process was carried out under reflux. Finally, the precipitate was crystallized and aged, washed until neutral, dried, and calcined in a muffle furnace to obtain the Cu. a Zr x Ce y O z catalyst.

2. The Cu according to claim 1 a Zr x Ce y O z The catalyst modification preparation method is characterized by: In step S01, the organic alcohol is one or more of anhydrous ethanol, n-propanol, ethylene glycol, glycerol, or n-butanol.

3. The Cu according to claim 2 a Zr x Ce y O z The catalyst modification preparation method is characterized by: In step S01: the cerium salt, zirconium salt and copper salt soluble in organic alcohols are respectively: cerium nitrate, zirconium nitrate and copper nitrate.

4. The Cu according to claim 1 a Zr x Ce y O z The catalyst modification preparation method is characterized by: In step S01: the molar concentration of the active component solution C1 is 0.5~2.0 mol / L, the molar concentration of the auxiliary agent solution C2 is 0.1~0.8 mol / L, and the mass fraction of the precipitant solution C3 is 20%~40% wt. The volume ratio of active component solution C1: auxiliary agent solution C2: precipitant solution C3 is 5:1:

2.

5. The Cu according to claim 1 a Zr x Ce y O z The catalyst modification preparation method is characterized by: In step S02: the C2 solution is slowly added dropwise to the C1 solution while stirring at 40℃~60℃, and the stirring time is 1~3h; the C3 solution is slowly added to the above mixed solution of C1 and C2 at 60℃~85℃ and pH is maintained at 8.0~10, and the stirring time is continued for 2~4h.

6. The Cu according to claim 1 a Zr x Ce y O z The catalyst modification preparation method is characterized by: In step S02, the temperature for aging the precipitate through crystallization is 90~120℃.

7. The Cu according to claim 1 a Zr x Ce y O z The catalyst modification preparation method is characterized by: In step S02, the time for aging the precipitate through crystallization is 8 to 24 hours.

8. The Cu according to claim 1 a Zr x Ce y O z The catalyst modification preparation method is characterized by: In step S02, the drying process conditions are: drying at 100~120℃ for 5-8 hours.

9. The Cu according to claim 1 a Zr x Ce y O z The catalyst modification preparation method is characterized by: In step S02: the heating rate of the muffle furnace during roasting is 1.5~3.5 ℃ / min.

10. The Cu according to claim 1 a Zr x Ce y O z The catalyst modification preparation method is characterized by: In step S02: the calcination process conditions in the muffle furnace are: calcination at 450~700℃ for 4~9 hours.