Copper-zinc catalyst, preparation method thereof and application of copper-zinc catalyst in preparation of ethanol by hydrogenation of methyl acetate

Abstract

The invention discloses a copper-zinc catalyst, a preparation method thereof and application of the copper-zinc catalyst in preparation of ethanol by hydrogenation of methyl acetate. Comprising the following steps: (1) mixing water, a silicon source, an aluminum source and alkali, stirring I, and crystallizing in a closed container to obtain a solution A; (2) mixing the solution A with an alkali solution, and stirring II to obtain a solution B; (3) mixing water, a copper source, a zinc source and an auxiliary agent source to obtain a solution C; and (4) mixing the solution B and the solution C, controlling the pH value to be 6.5-9.5, aging, washing, drying and roasting to obtain the copper-zinc catalyst. And carrying out hydrogen reduction on the copper-zinc catalyst, and carrying out hydrogenation reaction. The specific surface area of the catalyst prepared by the preparation method provided by the invention is increased, the particle size of the active species Cu is relatively small, the thermal stability of the catalyst is favorably improved, the catalytic activity is remarkably improved, and the catalyst has higher methyl acetate conversion rate and ethanol selectivity.

Description

Technical Field

[0001] This application relates to a copper-zinc catalyst, its preparation method, and its application in the hydrogenation of methyl acetate to ethanol, belonging to the field of catalysts. Background Technology

[0002] Ethanol, as an important industrial chemical, plays an irreplaceable and crucial role in various industrial fields such as chemical engineering, pharmaceuticals, and materials science due to its unique chemical and physical properties. Currently, ethanol production mainly relies on two traditional technological routes: biomass fermentation and chemical synthesis.

[0003] Among these technologies, biomass fermentation is relatively mature, but its reliance on grain crops as primary raw materials leads to a series of significant problems. From an economic perspective, the high overall costs associated with raw material procurement, processing losses, and supply chain management result in low overall economic viability for this process, thus placing continuous pressure on related production enterprises.

[0004] In contrast, the hydrogenation of methyl acetate to ethanol offers a new pathway to address these challenges. This process, through catalytic hydrogenation, effectively avoids dependence on grain feedstock, reducing production costs at the source. Furthermore, thanks to its highly selective reaction mechanism and optimized process conditions, this technology enables efficient ethanol synthesis, improving product purity and quality. Due to these significant advantages, the hydrogenation of methyl acetate to ethanol has garnered widespread attention from academia and industry in recent years, emerging as a promising new strategy for ethanol synthesis.

[0005] With the deepening of relevant basic research and the continuous progress of engineering application technologies, this process route is expected to achieve large-scale industrial application in the future and occupy an important position in the ethanol production technology landscape, promoting the ethanol industry towards a greener, more efficient and sustainable direction.

[0006] In the acetic acid ester hydrogenation reaction system, the sintering of the active catalyst component and the carbon deposition caused by side reactions are key factors affecting catalyst performance and service life. First, copper particles, the active component, are prone to migration and aggregation during the reaction. Driven by energy, the Brownian motion of copper atoms intensifies, causing particles to approach and fuse, forming larger particles. This process conforms to the basic principles of molecular dynamics, resulting in a significant decrease in the catalyst's specific surface area and the collapse and narrowing of the pore structure. Especially under high-temperature conditions, the thermal kinetic energy of copper and auxiliary metal particles increases, raising the collision frequency and effective collision probability, further exacerbating particle aggregation and growth. Second, while the main reaction proceeds, various side reactions occur within the system. From the perspective of organic reaction mechanisms, reactant molecules undergo non-selective adsorption and activation at active sites, which can be cleaved to generate unsaturated hydrocarbon intermediates. These species have high reactivity and readily form carbonaceous polymers on the catalyst surface through free radical polymerization or condensation mechanisms, gradually depositing as carbon deposits.

[0007] The aforementioned phenomena lead to the covering or destruction of active sites and a reduction in the number of active centers, resulting in a sharp decline in catalytic performance and ultimately catalyst deactivation, significantly shortening its lifespan. From an industrial application perspective, reduced catalyst lifespan not only increases procurement and replacement costs but also adversely affects process continuity and operational stability, thereby increasing operating costs and production risks. To address this issue, we are committed to developing a novel catalyst preparation strategy. This method is based on a systematic understanding of the interactions between active components, promoters, and supports. By precisely controlling the catalyst composition and microstructure, it enhances its resistance to sintering and carbon deposition under harsh reaction conditions, extending its lifespan and supporting the efficient and stable operation of the acetate hydrogenation to ethanol process. Summary of the Invention

[0008] According to the first aspect of this application, a method for preparing a copper-zinc catalyst is provided, comprising the following steps: (1) Mix water, silicon source, aluminum source and alkali, stir I, and crystallize in a sealed container to obtain solution A; (2) Mix solution A with alkaline solution and stir II to obtain solution B; (3) Mix water, copper source, zinc source and auxiliary agent source to obtain solution C; (4) Mix solution B and solution C, control the pH to 6.5~9.5, age, wash, dry, and calcine to obtain copper-zinc catalyst.

[0009] Solution A obtained in step (1) contains a layered hydrohydroxysodium silicate structure; solution B obtained in step (2) contains a hydrohydroxysodium silicate structure; in step (4), solution B can be added dropwise to solution C, solution C can be added dropwise to solution B, or solution B and solution C can be co-precipitated.

[0010] Optionally, in step (1), the silicon source is selected from at least one of silica sol, methyl orthosilicate, ethyl orthosilicate, sodium silicate, and diatomaceous earth; The aluminum source is selected from at least one of sodium aluminate, aluminum isopropoxide, aluminum hydroxide, aluminum sol, and boehmite. The alkali is selected from at least one of sodium carbonate, sodium bicarbonate, ammonium carbonate, sodium hydroxide, potassium hydroxide, and ammonia.

[0011] Optionally, in step (1), the molar ratio of silicon source to aluminum source in solution A is SiO2:Al2O3 = 100:1~5.

[0012] Optionally, the molar ratio of silicon source to aluminum source is any value among 100:1, 100:1.5, 100:2, 100:2.5, 100:3, 100:3.5, 100:4, and 100:5, or any range between the two.

[0013] Optionally, in step (1), the molar ratio of silicon source to alkali is SiO2:M2O=100:3~6.

[0014] Optionally, the molar ratio of silicon source to alkali is any value among 100:3, 100:3.5, 100:4, 100:4.5, 100:5, 100:5.5, and 100:6, or any range between the two.

[0015] Optionally, in step (1), the molar ratio of silicon source to water is SiO2:H2O=1:15~40.

[0016] The number of moles of silicon source is calculated based on the number of moles of SiO2 contained in the silicon source, the number of moles of aluminum source is calculated based on the number of moles of Al2O3 contained in the aluminum source, and the number of moles of alkali is calculated based on the number of M2O contained in the alkali.

[0017] Optionally, in step (3), the copper source is selected from at least one of copper nitrate, sulfate, carbonate, chloride, and acetate. The zinc source is selected from at least one of zinc nitrate, sulfate, carbonate, chloride, and acetate. The auxiliary agent source is selected from at least one of the nitrate, carbonate, and chloride corresponding to the auxiliary agent element; The auxiliary element is selected from at least one of calcium, nickel, barium, iron, molybdenum, aluminum, cerium, chromium, palladium, magnesium, and manganese.

[0018] Optionally, in step (1), the crystallization temperature is 40~150℃; The crystallization time is 2~240 h.

[0019] Optionally, the crystallization temperature is any value or a range between 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, and 150°C.

[0020] Optionally, the crystallization time is any value among 2 h, 5 h, 10 h, 50 h, 100 h, 150 h, 200 h, and 240 h, or a range between any two.

[0021] Optionally, in step (1), the stirring time is 20~240 min.

[0022] Optionally, the stirring time I is any value or a range between 20 min, 40 min, 60 min, 80 min, 100 min, 120 min, 140 min, 160 min, 180 min, 200 min, 220 min, and 240 min.

[0023] Optionally, in step (1), the temperature of stirring I is 0℃~100℃.

[0024] Optionally, in step (3), the aging temperature is 20℃~100℃; The aging time is 0~300 min.

[0025] Optionally, the aging temperature is any value among 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, and 100°C, or a range between any two.

[0026] Optionally, the aging time is any value or a range between any two of 20 min, 40 min, 60 min, 80 min, 100 min, 120 min, 140 min, 160 min, 180 min, 200 min, 220 min, 240 min, 260 min, 280 min, and 300 min.

[0027] Optionally, in step (3), the drying temperature is 20℃~200℃; The drying time is 0~30 h.

[0028] Optionally, the calcination temperature is 200℃~600℃; The roasting time is 0~10 h; The heating rate during calcination is 0.01℃ / min to 30℃ / min.

[0029] Optionally, the roasting temperature is any value among 200℃, 300℃, 400℃, 500℃, and 600℃, or a range between any two.

[0030] Optionally, the roasting time is any value among 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, and 10 h, or a range between any two.

[0031] Optionally, in step (4), the catalyst precursor contains a layered crystalline phase.

[0032] According to a second aspect of this application, a copper-zinc catalyst is provided.

[0033] Optionally, in the copper-zinc catalyst, the mass ratio of CuO to ZnO is 1:0.01~5.

[0034] Optionally, the mass ratio of CuO to ZnO is any value from 1:0.01, 1:0.05, 1:0.1, 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5 or any range between the two.

[0035] Optionally, in the copper-zinc catalyst, the auxiliary element accounts for 0.1 to 10 wt% of the catalyst mass based on the mass of its oxide.

[0036] Optionally, the auxiliary element, based on the mass of its oxide, comprises any value from 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt% of the mass of the catalyst, or a range between any two.

[0037] Optionally, the specific surface area of ​​the copper-zinc catalyst is 50-150 m². 2 / g, pore size is 5-50 nm, pore volume is 0.2-1.0 mL / g.

[0038] Optionally, in the copper-zinc catalyst, the CuO crystallite size is 1.0~8.0 nm and the ZnO crystallite size is 1.0~8.0 nm.

[0039] According to a third aspect of this application, a method for producing ethanol by hydrogenation of methyl acetate is provided.

[0040] A method for hydrogenating methyl acetate to ethanol includes the following steps: treating the copper-zinc catalyst described above with hydrogen; Ethanol is produced by reacting a feed gas containing methyl acetate and hydrogen with a reduced copper-zinc catalyst.

[0041] Optionally, the temperature for hydrogen reduction is 20°C to 400°C; The heating rate for hydrogen reduction is 0.01℃ / min to 30℃ / min; The hydrogen reduction time is 0.01~300 min.

[0042] Optionally, the temperature for hydrogen reduction is any value or a range between 20°C, 50°C, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C, and 400°C.

[0043] Optionally, the hydrogen reduction time is any value or a range between any two of 20 min, 50 min, 100 min, 120 min, 140 min, 160 min, 180 min, 200 min, 220 min, 240 min, 260 min, 280 min, and 300 min.

[0044] Optionally, the molar ratio of methyl acetate to hydrogen is 1:2 to 50.

[0045] Optionally, the mass hourly space velocity (WHSV) of methyl acetate is 0.2–10 h⁻¹. -1 .

[0046] Optionally, the reaction temperature is 100~600℃.

[0047] Optionally, the reaction pressure is 1~10 MPa.

[0048] Optionally, the molar ratio of methyl acetate to hydrogen is independently selected from any value among 1:2, 1:4, 1:5, 1:6, 1:8, 1:10, 1:12, 1:14, 1:15, 1:16, 1:18, 1:20, 1:22, 1:24, 1:25, 1:26, 1:28, 1:30, 1:32, 1:35, 1:38, 1:40, 1:45, and 1:50, or a range between any two of the above.

[0049] Optionally, the mass hourly space velocity (WHSV) of methyl acetate is independently selected from 0.2 h⁻¹. -1 0.4 h -1 0.5 h -1 1 h -1 1.5 h -1 2 h -1 2.5 h -1 3 h -1 3.5 h -1 4 h -1 4.5 h -1 5 h-1 5.5 h -1 6 h -1 6.5 h -1 7 h -1 7.5 h -1 8 h -1 8.5 h -1 9 h -1 9.5 h -1 10 h -1 Any value in the range or any two points mentioned above.

[0050] Optionally, the temperature of the reaction is independently selected from any value of 100℃, 150℃, 200℃, 250℃, 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, 600℃ or a range between any two of the above points.

[0051] Optionally, the pressure of the reaction is independently selected from any value of 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa or a range between any two of the above points.

[0052] The beneficial effects that this application can produce include: The catalyst prepared by the method proposed in this application exhibits two key changes at the microstructural level: firstly, the specific surface area of ​​the catalyst is significantly increased; secondly, the size of the active species Cu particles is significantly reduced. These two microstructural changes do not occur in isolation, but interact in a synergistic coupling manner.

[0053] From the perspective of the mechanism of action, the increase in specific surface area provides more active sites for the catalytic reaction, while the reduction in the size of Cu particles, an active species, makes the active centers more dispersed and efficient. The synergistic effect of these two factors first positively impacts the thermal stability of the catalyst. By optimizing the interactions between particles and enhancing the binding force between the active component and the support, the migration and sintering of active species at high temperatures are effectively suppressed, thereby stabilizing the thermal stability of the catalyst.

[0054] Building upon this, stable thermal stability creates favorable conditions for enhancing catalytic activity. The abundant active sites and highly dispersed active centers work together to greatly promote the adsorption, activation, and transformation of reactant molecules on the catalyst surface, thereby significantly improving catalytic activity. Ultimately, driven by the enhanced catalytic activity, the conversion and selectivity of the hydrogenation reaction are optimized, achieving superior performance and fully demonstrating the significant advantages of the preparation method presented in this application in improving catalyst performance. Attached Figure Description

[0055] Figure 1 The images show the XRD patterns of the catalyst precursors in Example 1 and Comparative Example 1 of this application.

[0056] Figure 2 The images show the XRD patterns of the catalysts in Example 1 and Comparative Example 1 of this application.

[0057] Figure 3 This is a pore size distribution diagram of the catalysts in Example 1 and Comparative Example 1 of this application.

[0058] Figure 4 The images show the pore volume diagrams of the catalysts in Example 1 and Comparative Example 1 of this application. Detailed Implementation

[0059] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0060] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0061] The analysis method in the embodiments of this application is as follows: XRD analysis was performed using a Rigaku ZSX PrimusⅢ+ fluorescence spectrometer.

[0062] BET analysis was performed using the Autosorb iQ 2MP physical adsorption system from Anton Paconta Systems, Inc.

[0063] In the embodiments of this application, the conversion rate and selectivity are calculated as follows: Methyl acetate conversion rate (%) = (moles of methyl acetate in feed - moles of methyl acetate in product) / moles of methyl acetate in feed * 100%; Product selectivity (%) = number of moles converted to product / number of moles of methyl acetate converted * 100%.

[0064] Initial evaluation conditions: In a fixed-bed reactor, a feed gas containing methyl acetate and hydrogen was contacted with the catalyst. The molar ratio of methyl acetate to hydrogen was 1:25, and the mass hourly space velocity (WHSV) of methyl acetate was 1.5 h⁻¹. -1 The reaction was carried out at 200℃ and 5 MPa, and the composition of the product was analyzed by gas chromatography. The test results are detailed in Table 2.

[0065] Stringent evaluation conditions: In a fixed-bed reactor, a feed gas containing methyl acetate and hydrogen is contacted with the catalyst. The molar ratio of methyl acetate to hydrogen is 1:10, and the mass hourly space velocity (WHSV) of methyl acetate is 2.5 h⁻¹. -1The reaction was carried out under 5 MPa conditions. After stabilizing at 200℃, the temperature was increased to 500℃ while keeping other operating conditions unchanged for 10 h. Then, the temperature was lowered to 200℃ until the reaction stabilized. The composition of the product was analyzed using gas chromatography. The test results are detailed in Table 2.

[0066] Comparative Example 1 A 1.5 mol / L aqueous solution (salt solution) was prepared by dissolving 198.98 g of copper nitrate trihydrate, 75.375 g of zinc nitrate hexahydrate, 45 g of aluminum nitrate nonahydrate, and 3.25 g of cerium nitrate hexahydrate in water. An alkaline solution was prepared by dissolving sodium bicarbonate in water to a concentration of 1.5 mol / L. The salt and alkaline solutions were then added dropwise to a reaction beaker using a dropping funnel. The mixture was stirred magnetically at 400 rpm in the reaction beaker, and the reaction temperature was controlled at 60°C. o C. After the reaction was completed, the sample was aged at 200 rpm and 60℃ for 2 h. The aged sample was washed with deionized water until the filtrate was neutral, and then dried at 120℃ for 10 h to obtain the catalyst precursor. This precursor was then calcined at a heating rate of 5℃ / min for 8 h at 500℃ to obtain the catalyst, denoted as catalyst CO#. The mass ratio of CuO to ZnO in the obtained catalyst was 1:0.31.

[0067] Example 1 Take 2 g of aluminum sol with a content of 20 wt% Al2O3, 24.5 g of silica sol with a content of 30 wt% SiO2, 5.3 g of sodium hydroxide, add 68 g of deionized water, and stir at room temperature for 120 min to obtain a slurry-like mixed solution. Transfer the mixed solution to a closed stainless steel high-pressure hydrothermal reactor to begin crystallization at 100℃ for 60 h to obtain solution A. Add 0.8 L of 1.5 mol / L Na2CO3 solution to solution A and stir to obtain solution B. Prepare a 1.5 mol / L solution C by mixing 198.98 g of copper nitrate trihydrate, 75.375 g of zinc nitrate hexahydrate, 45 g of aluminum nitrate nonahydrate, and 3.25 g of cerium nitrate hexahydrate. Solution B and solution C were added dropwise to a beaker for a co-precipitation reaction. After the reaction, the sample was aged at 60℃ for 2 h with magnetic stirring at 200 rpm. The aged sample was washed with deionized water until the filtrate was neutral, and then dried at 120℃ for 10 h to obtain the catalyst precursor. This precursor was then calcined at a heating rate of 5℃ / min for 8 h at 500℃ to obtain the catalyst, designated as catalyst 1#. In the obtained catalyst, the mass ratio of CuO to ZnO was 1:0.31, and the promoter Ce, based on the mass of its oxide, accounted for 1.29 wt% of the catalyst mass.

[0068] Example 2 The catalyst was prepared according to the method described in Example 1 above, except that the silicon source in solution A was 122.5 mL of 1 mol / L tetraethyl orthosilicate, and the aluminum source was 3 g of aluminum nitrate nonahydrate. This was designated as catalyst 2#. In the obtained catalyst, the mass ratio of CuO to ZnO was 1:0.31, and the promoter Ce, based on the mass of its oxide, accounted for 1.29 wt% of the catalyst mass.

[0069] Example 3 The catalyst was prepared according to the method described in Example 1 above, except that solution A contained 122.5 mL of 1 mol / L tetraethyl orthosilicate as the silicon source, 0.8 g of 78% boehmite (dry basis), 7 g of sodium hydroxide, and 85 g of deionized water. This was designated as catalyst #3. In the obtained catalyst, the mass ratio of CuO to ZnO was 1:0.31, and the promoter Ce, based on the mass of its oxide, accounted for 1.29 wt% of the catalyst mass.

[0070] Example 4 The catalyst was prepared according to the method described in Example 1 above, except that the Na2CO3 concentration in solution B was 1.6 mol / L, and 230 g of copper nitrate trihydrate, 80 g of zinc nitrate hexahydrate, 20 g of aluminum nitrate nonahydrate, and 3 g of cerium nitrate hexahydrate were prepared into a 1.6 mol / L solution C. This solution is designated as catalyst 4#. In the obtained catalyst, the mass ratio of CuO to ZnO was 1:0.30, and the promoter Ce, based on the mass of its oxide, accounted for 1.08 wt% of the catalyst mass.

[0071] Example 5 The catalyst was prepared according to the method described in Example 1 above, except that aluminum nitrate and cerium nitrate in solution C were replaced with 7.5 g of zirconium nitrate pentahydrate. This was designated as catalyst 5#. In the obtained catalyst, the mass ratio of CuO to ZnO was 1:0.31, and the promoter Zr, based on the mass of its oxide, accounted for 2.11 wt% of the catalyst mass.

[0072] Example 6 The catalyst was prepared according to the method described in Example 1 above, except that in solution C, cerium nitrate hexahydrate was replaced with 9.5 g of magnesium nitrate hexahydrate. This was designated as catalyst 6#. In the obtained catalyst, the mass ratio of CuO to ZnO was 1:0.31, and the promoter Mg, based on the mass of its oxide, accounted for 1.5 wt% of the catalyst mass.

[0073] Example 7 The catalyst was prepared according to the method described in Example 1 above, except that during the preparation of solution A, the solution was stirred at 60°C for 100 min to obtain a slurry-like mixed solution. The mixed solution was then transferred to a closed stainless steel high-pressure hydrothermal reactor to begin crystallization at 120°C for 24 h, yielding solution A. This solution is designated as catalyst 7#. In the obtained catalyst, the mass ratio of CuO to ZnO is 1:0.31, and the promoter Ce, based on the mass of its oxide, accounts for 1.29 wt% of the catalyst mass.

[0074] Example 8 The catalyst was prepared according to the method described in Example 1 above, except that the crystallization temperature was 120°C and the crystallization time was 48 h during the preparation of solution A, resulting in solution A. This solution is designated as catalyst 8#. In the obtained catalyst, the mass ratio of CuO to ZnO was 1:0.31, and the promoter Ce, based on the mass of its oxide, accounted for 1.29 wt% of the catalyst mass.

[0075] Example 9 The catalyst was prepared according to the method described in Example 1 above, except that solutions B and C were added dropwise together to a beaker and a co-precipitation reaction was carried out at 70°C. This was designated as catalyst 9#. In the obtained catalyst, the mass ratio of CuO to ZnO was 1:0.31, and the promoter Ce, based on the mass of its oxide, accounted for 1.29 wt% of the catalyst mass.

[0076] Characterization tests of catalysts Taking Example 1 as an example, the XRD patterns of the catalyst precursors in Example 1 and Comparative Example 1 are as follows: Figure 1 As shown, compared with Comparative Example 1, the catalyst precursor obtained in Example 1 exhibits characteristic peaks of a layered crystalline phase (2θ values ​​of 4.6, 6.11, and 7.2), indicating a more uniform and ordered arrangement of crystalline phases within the catalyst. The XRD patterns of the catalysts in Example 1 and Comparative Example 1 are shown below. Figure 2 As shown, the crystallite size was calculated using the Scherrer formula, and the specific data are shown in Table 1. It can be seen that the crystallite sizes of CuO and ZnO catalysts in Example 1 are smaller than the corresponding crystallite sizes in the catalyst of Comparative Example 1. The effective components of the catalyst exhibit high internal dispersion, making them more readily react with the reaction medium for hydrogenation, directly affecting the improvement of the catalyst's hydrogenation activity. The pore size distribution diagrams and pore volume diagrams of the catalysts in Example 1 and Comparative Example 1 are shown below. Figure 3 , Figure 4As shown in Table 1, the specific surface area, pore volume, and pore size data are as follows. It can be seen that the catalyst prepared in Example 1 has a larger specific surface area, pore volume, and pore size than the catalyst prepared by the conventional method in the comparative example. The increase in specific surface area, pore volume, and pore size indicates that the internal structure of the catalyst has changed, which directly affects the mass transfer, heat transfer, and internal diffusion of reactants, products, and intermediate species, and further directly affects the initial hydrogenation activity and stability of the catalyst.

[0077] Table 1. Structural parameters of the catalysts obtained in Example 1 and Comparative Example 1

[0078] Catalyst performance evaluation Before the reaction, the catalysts in the above embodiments and comparative examples were subjected to hydrogen reduction treatment. Specifically, the catalysts were reduced under a hydrogen to nitrogen volume ratio of 1:2, with a heating rate of 5°C / min, and treated at 300°C for 240 min. Then, the reaction was carried out according to the initial evaluation conditions and the stringent evaluation conditions. The specific data are shown in Table 2.

[0079] Table 2 Performance Evaluation Data Table

[0080] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing a copper-zinc catalyst, characterized in that, Includes the following steps: (1) Mix water, silicon source, aluminum source and alkali, stir I, and crystallize in a sealed container to obtain solution A; (2) Mix solution A with alkaline solution and stir II to obtain solution B; (3) Mix water, copper source, zinc source and auxiliary agent source to obtain solution C; (4) Mix solution B and solution C, control the pH to 6.5~9.5, age, wash, dry to obtain catalyst precursor, calcine to obtain copper-zinc catalyst.

2. The preparation method according to claim 1, characterized in that, In step (1), the silicon source is selected from at least one of silica sol, methyl orthosilicate, ethyl orthosilicate, sodium silicate, and diatomaceous earth; The aluminum source is selected from at least one of sodium aluminate, aluminum isopropoxide, aluminum hydroxide, aluminum sol, and boehmite. The alkali is selected from at least one of sodium carbonate, sodium bicarbonate, ammonium carbonate, sodium hydroxide, potassium hydroxide, and ammonia.

3. The preparation method according to claim 1, characterized in that, In step (1), the molar ratio of silicon source to aluminum source in solution A is SiO2:Al2O3 = 100:1~5; The molar ratio of silicon source to alkali is SiO2:M2O = 100:3~6; The molar ratio of silicon source to water is SiO2:H2O = 1:15~40; The number of moles of silicon source is calculated based on the number of moles of SiO2 contained in the silicon source, the number of moles of aluminum source is calculated based on the number of moles of Al2O3 contained in the aluminum source, and the number of moles of alkali is calculated based on the number of M2O contained in the alkali.

4. The preparation method according to claim 1, characterized in that, In step (3), the copper source is selected from at least one of copper nitrate, sulfate, carbonate, chloride, and acetate. The zinc source is selected from at least one of zinc nitrate, sulfate, carbonate, chloride, and acetate. The auxiliary agent source is selected from at least one of the nitrate, carbonate, and chloride corresponding to the auxiliary agent element; The auxiliary element is selected from at least one of calcium, nickel, barium, iron, molybdenum, aluminum, cerium, chromium, palladium, magnesium, and manganese.

5. The preparation method according to claim 1, characterized in that, In step (1), the crystallization temperature is 40~150℃; The crystallization time is 2~240 h; Preferably, in step (1), the stirring time is 20~240 min.

6. The preparation method according to claim 1, characterized in that, In step (3), the aging temperature is 20℃~100℃; The aging time is 0~300 min; Preferably, in step (3), the drying temperature is 20℃~200℃; The drying time is 0~30 h; The roasting temperature is 200℃~600℃; The roasting time is 0~10 h; The heating rate during calcination is 0.01℃ / min to 30℃ / min.

7. The preparation method according to claim 1, characterized in that, In step (4), the catalyst precursor contains a layered crystalline phase.

8. The copper-zinc catalyst prepared by the preparation method according to any one of claims 1 to 7, characterized in that, In the copper-zinc catalyst, the mass ratio of CuO to ZnO is 1:0.01~5; In the copper-zinc catalyst, the auxiliary element, based on the mass of its oxide, accounts for 0.1~10 wt% of the catalyst mass. Preferably, the specific surface area of ​​the copper-zinc catalyst is 50-150 m². 2 / g, pore size is 5-50 nm, pore volume is 0.2-1.0 mL / g; CuO crystallite size is 1.0~8.0 nm, ZnO crystallite size is 1.0~8.0 nm.

9. A method for producing ethanol by hydrogenation of methyl acetate, characterized in that, The process includes the following steps: subjecting the copper-zinc catalyst of claim 8 to hydrogen reduction treatment; Ethanol is produced by reacting a feed gas containing methyl acetate and hydrogen with a reduced copper-zinc catalyst.

10. The method according to claim 9, characterized in that, The temperature for hydrogen reduction is 20℃~400℃; The heating rate for hydrogen reduction is 0.01℃ / min to 30℃ / min; The hydrogen reduction time is 0.01~300 min; Preferably, the molar ratio of methyl acetate to hydrogen is 1:2 to 50, and the mass hourly space velocity (WHSV) of methyl acetate is 0.2 to 10 h⁻¹. -1 The reaction temperature is 100~600℃, and the reaction pressure is 1~10 MPa.

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