Ester hydrogenation catalyst, method for preparing the same, and use thereof

Abstract

The application discloses an ester hydrogenation catalyst and a preparation method and application thereof, and belongs to the field of chemical catalyst preparation. The ester hydrogenation catalyst comprises CuO and ZnO; the molar ratio of the CuO to the ZnO is 5:1-1:5; the specific surface area of the ester hydrogenation catalyst is 95-120 m 2 / g. The catalyst is an alloy catalyst, has small particle size, high dispersity, strong anti-sintering performance and good catalytic activity, and is used for hydrogenation of esters to prepare low-carbon alcohols, and the reaction condition is relatively mild, the hydrogen-ester ratio is low, the raw material conversion rate is high, and the product selectivity is high.

Description

Technical Field

[0001] This application relates to an ester hydrogenation catalyst, its preparation method, and its application, belonging to the field of chemical catalyst preparation. Background Technology

[0002] Alcohols generally refer to compounds in which a hydroxyl group is attached to an aliphatic hydrocarbon group. They have wide applications in chemical industry, medical and health care, food industry, and agricultural production. Lower alcohols can be used as lubricants, fuel additives, and are widely used in the synthesis of pharmaceutical intermediates; for example, ethanol can be used to produce acetic acid, fragrances, and dyes, and can also be used as a clean fuel; ethylene glycol can be used to prepare polyesters, polyester fibers, plasticizers, and surfactants. Higher alcohols refer to alcohols containing six or more carbon atoms and are mainly used in the synthesis of plasticizers and surfactants.

[0003] Conventional alcohol synthesis routes include fermentation, olefin hydration, hydrogenation after carbonylation, direct hydrogenation of organic acids, and ester hydrogenation. Fermentation for alcohol synthesis is inefficient and has drawbacks, competing with food resources and land. While olefin hydration offers high selectivity, it suffers from extremely low conversion rates, high reaction pressures, large water consumption, and difficult separation. Olefin carbonylation hydrogenation involves harsh hydroformylation reaction conditions; even with precious metal catalysts under high pressure, yields remain low. Organic acid hydrogenation requires acid-resistant catalysts and is highly corrosive to reaction equipment. In contrast, ester hydrogenation uses inexpensive metal catalysts under suitable reaction conditions to achieve high conversion rates and selectivity, with lower requirements for reaction equipment, making it widely applicable for industrial production.

[0004] Traditional methods for ester hydrogenation use LiAlH4 or NaHB4 reduction, but their operational hazards and high cost limit their widespread application. Homogeneous catalytic systems, such as diethylamine tridentate pincer ligand catalysts, have also been studied, but these systems face challenges such as difficulty in separating the catalyst from the product and catalyst loss, hindering industrial production. Currently, copper-silicon and copper-zinc catalysts are the most studied. Copper-based catalysts have weaker ability to dissociate C=C bonds, but they exhibit high selectivity for hydrogenating C=O bonds and are inexpensive, thus gaining widespread use. Research has found that in Cu-Zn-based catalysts, the dispersion of Cu and the synergistic effect of the Cu-Zn interface play a crucial role in catalyst activity. The presence of Zn increases the specific surface area of ​​the catalyst, disperses Cu, and helps improve the catalyst's thermal stability, significantly enhancing catalytic activity. Among these, copper-silicon catalysts show superior conversion and selectivity in hydrogenation, but their relatively poor thermal stability and the risk of silane formation side reactions limit their industrial application compared to copper-zinc catalysts. Summary of the Invention

[0005] According to the first aspect of this application, an ester hydrogenation catalyst is provided. This catalyst is an alloy catalyst with small particle size, high dispersibility, strong anti-sintering properties, and good catalytic activity. When used for the hydrogenation of esters to produce lower alcohols, it provides relatively mild reaction conditions, a low hydrogen-ester ratio, high feed conversion rate, and high product selectivity.

[0006] With a large copper specific surface area and strong copper-zinc synergistic effect, the key to maintaining the catalyst's reactivity and improving its performance lies in promoting the uniformity of copper-zinc distribution within the catalyst. Smaller copper-zinc particle sizes and higher dispersion result in a larger copper specific surface area, stronger copper-zinc interfacial synergistic effect, and naturally, higher catalytic performance. However, how to increase the catalyst's specific surface area and enhance the copper-zinc interfacial synergistic effect remains a direction for ongoing research. This application increases the catalyst's dispersion and improves its hydrogenation performance by adding a dispersant to reduce the copper-zinc particle size and guide metal alignment.

[0007] An ester hydrogenation catalyst, said ester hydrogenation catalyst comprising CuO and ZnO;

[0008] The molar ratio of CuO to ZnO is 0.2-5;

[0009] Optionally, the molar ratio of CuO to ZnO is independently selected from any value among 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, and 5.0, or a range between any two.

[0010] The specific surface area of ​​the ester hydrogenation catalyst is 95-120 m². 2 / g.

[0011] Optionally, the specific surface area of ​​the ester hydrogenation catalyst is independently selected from 95 m². 2 / g、96m 2 / g、97m 2 / g、98m 2 / g、99m 2 / g, 100m 2 / g、101m 2 / g、102m 2 / g、103m 2 / g, 104m 2 / g, 105m 2 / g, 106m 2 / g, 107m 2 / g, 108m 2 / g、109m 2 / g、110m 2 / g、111m 2 / g、112m 2 / g、113m 2 / g、114m 2 / g、115m 2 / g、116m 2 / g、117m 2 / g、118m 2 / g、119m 2 / g、120m 2 Any value in / g or any range between the two.

[0012] Optionally, the ester hydrogenation catalyst further includes promoter A and / or promoter B and / or promoter C;

[0013] The auxiliary agent A is selected from one or more of Group IIA oxides, and its content in the ester hydrogenation catalyst is 0.0-50.0 wt% based on metal element.

[0014] The auxiliary agent B is selected from one or more of Group IIIA oxides, and its content in the ester hydrogenation catalyst is 0.0-50.0 wt% based on metal element.

[0015] The auxiliary agent C is selected from one or a mixture of several group IIB-VIIB oxides, and its content in the ester hydrogenation catalyst is 0.0-50.0 wt% based on metal element.

[0016] Optionally, in the ester hydrogenation catalyst, the active component Cu, calculated as a metal element, has a weight percentage of 10.0-50.0 wt%.

[0017] Optionally, the pore volume of the ester hydrogenation catalyst is 0.7000-0.9500 ml / g.

[0018] Optionally, the pore volume of the ester hydrogenation catalyst is independently selected from 0.7000 ml / g, 0.7100 ml / g, 0.7200 ml / g, 0.7300 ml / g, 0.7400 ml / g, 0.7500 ml / g, 0.7600 ml / g, 0.7700 ml / g, 0.7800 ml / g, 0.7900 ml / g, 0.8000 ml / g, 0.8100 ml / g, and 0.8200 ml / g. The value can be any value from 0.8300ml / g, 0.8400ml / g, 0.8500ml / g, 0.8600ml / g, 0.8700ml / g, 0.8800ml / g, 0.8900ml / g, 0.9000ml / g, 0.9100ml / g, 0.9200ml / g, 0.9300ml / g, 0.9400ml / g, 0.9500ml / g, or any value within a range of two.

[0019] Optionally, the CuO has a particle size of 7.5-9.0 nm.

[0020] Optionally, the particle size of the CuO is independently selected from any value or a range between 7.5nm, 7.6nm, 7.7nm, 7.8nm, 7.9nm, 8.0nm, 8.1nm, 8.2nm, 8.3nm, 8.4nm, 8.5nm, 8.6nm, 8.7nm, 8.8nm, 8.9nm, and 9.0nm.

[0021] Optionally, the ZnO has a particle size of 9.0-12.0 nm.

[0022] Optionally, the particle size of the ZnO is independently selected from any value or a range between 9.0 nm, 9.1 nm, 9.2 nm, 9.3 nm, 9.4 nm, 9.5 nm, 9.6 nm, 9.7 nm, 9.8 nm, 9.9 nm, 10.0 nm, 10.1 nm, 10.2 nm, 10.3 nm, 10.4 nm, 10.5 nm, 10.6 nm, 10.7 nm, 10.8 nm, 10.9 nm, 11.0 nm, 11.1 nm, 11.2 nm, 11.3 nm, 11.4 nm, 11.5 nm, 11.6 nm, 11.7 nm, 11.8 nm, 11.9 nm, and 12.0 nm.

[0023] According to a second aspect of this application, a method for preparing an ester hydrogenation catalyst is provided. This application uses a Cu / ZnO catalyst as a base, adding a dispersant. The effects of the type, amount, and relative molecular mass of the dispersant on the purity, dispersion performance, particle size, size distribution, and morphology of the product are explained. Furthermore, the composition and structure of the active sites of the Cu-based catalyst are controlled. Adding the dispersant during co-precipitation and aging not only helps to form ordered structures of different metals, increasing the specific surface area of ​​the catalyst, but also promotes crystal facet growth, thereby improving the ester hydrogenation performance of the catalyst.

[0024] A method for preparing an ester hydrogenation catalyst includes the following steps:

[0025] The ester hydrogenation catalyst is obtained by precipitating, aging, filtering, drying, and calcining a mixture containing Cu source, Zn source, precipitant, and dispersant.

[0026] or,

[0027] S1. The intermediate product is obtained by precipitating a mixture containing Cu source, Zn source and precipitant.

[0028] S2. A solution containing a dispersant is added to the intermediate product, and the product is aged, filtered, dried, and calcined to obtain the ester hydrogenation catalyst.

[0029] Optionally, a mixture containing a Cu source, a Zn source, a precipitant, and a dispersant is precipitated to obtain an intermediate product. A solution containing the dispersant is added to the intermediate product, and the mixture is aged, filtered, dried, and calcined to obtain the ester hydrogenation catalyst.

[0030] Optionally, the Cu source and the Zn source are independently selected from at least one of their respective nitrates, sulfates, carbonates, chlorides, and acetates.

[0031] Optionally, the precipitant is selected from at least one of sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium hydroxide, ammonia, and ammonium carbonate.

[0032] Optionally, the dispersant is selected from at least one of hydrophilic cationic surfactants and hydrophilic nonionic surfactants.

[0033] Optionally, the hydrophilic cationic surfactant includes amine salts, quaternary ammonium salts, nitrogen-based benzenes, and imidazolines. Optionally, the hydrophilic nonionic surfactant includes polyethylene glycol type, fatty alcohol amide type, and polyol type.

[0034] Optionally, the concentrations of the Cu source and the Zn source in the mixture are 0.001-10 mol / L.

[0035] Optionally, the concentrations of the Cu source and the Zn source are independently selected from any value or a range between any two of the following: 0.001 mol / L, 0.002 mol / L, 0.003 mol / L, 0.004 mol / L, 0.005 mol / L, 0.006 mol / L, 0.007 mol / L, 0.008 mol / L, 0.009 mol / L, 0.010 mol / L, 0.050 mol / L, 0.100 mol / L, 0.500 mol / L, 1.000 mol / L, 2.000 mol / L, 3.000 mol / L, 4.000 mol / L, 5.000 mol / L, 6.000 mol / L, 7.000 mol / L, 8.000 mol / L, 9.000 mol / L, and 10.000 mol / L.

[0036] Optionally, the concentration of the precipitant is 0.001-10 mol / L.

[0037] Optionally, the concentration of the precipitant is independently selected from any value or a range between any two of 0.001 mol / L, 0.002 mol / L, 0.003 mol / L, 0.004 mol / L, 0.005 mol / L, 0.006 mol / L, 0.007 mol / L, 0.008 mol / L, 0.009 mol / L, 0.010 mol / L, 0.050 mol / L, 0.100 mol / L, 0.500 mol / L, 1.000 mol / L, 2.000 mol / L, 3.000 mol / L, 4.000 mol / L, 5.000 mol / L, 6.000 mol / L, 7.000 mol / L, 8.000 mol / L, 9.000 mol / L, and 10.000 mol / L.

[0038] Alternatively, the precipitation conditions are as follows:

[0039] The temperature is 50-100℃.

[0040] Optionally, the precipitation temperature is independently selected from any value of 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, or a range between any two.

[0041] Optionally, the pH value is 6.5-9.5 during precipitation.

[0042] Optionally, during precipitation, the pH value is independently selected from any value among 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, and 9.5, or a range between any two.

[0043] Alternatively, the aging conditions are as follows:

[0044] The temperature is 50-100℃;

[0045] The time is 0.5-10 hours.

[0046] Optionally, the aging temperature is independently selected from any value of 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, or a range between any two.

[0047] Optionally, the aging time is independently selected from any value or a range between 0.5h, 1.0h, 2.0h, 3.0h, 4.0h, 5.0h, 6.0h, 7.0h, 8.0h, 9.0h, and 10.0h.

[0048] Optionally, stirring may be performed during the aging process;

[0049] The stirring speed is 0-1000 rpm.

[0050] Optionally, the following steps are included:

[0051] A1. Prepare salt solutions containing Cu source, salt solutions containing Zn source, aqueous solutions containing precipitant, and aqueous solutions containing dispersant, respectively.

[0052] A2. A salt solution containing Cu source, a salt solution containing Zn source, an aqueous solution containing precipitant, and an aqueous solution containing dispersant are added to a reactor for co-precipitation. After aging, filtration, drying, and calcination, the ester hydrogenation catalyst is obtained.

[0053] or,

[0054] B1. Prepare salt solutions containing Cu source, salt solutions containing Zn source, aqueous solutions containing precipitant, and aqueous solutions containing dispersant, respectively.

[0055] B2. A salt solution containing Cu, a salt solution containing Zn, and an aqueous solution containing a precipitant are added to a reactor for co-precipitation. When the precipitate is formed, an aqueous solution containing a dispersant is added, and the mixture is aged, filtered, dried, and calcined to obtain the ester hydrogenation catalyst.

[0056] In A1, a mixed salt solution of Cu and Zn sources is prepared.

[0057] The concentration of the mixed salt solution is 0.001-10 mol / L.

[0058] According to a third aspect of this application, an application of an ester hydrogenation catalyst is provided.

[0059] A method for the catalytic hydrogenation of methyl acetate to ethanol, using the ester hydrogenation catalyst described above.

[0060] A method for the catalytic hydrogenation of dimethyl oxalate to ethylene glycol, characterized in that the ester hydrogenation catalyst described above is used.

[0061] According to one embodiment of this application, this application provides a solution one:

[0062] (1) Prepare salt solutions and precipitant solutions of Cu and Zn respectively, and prepare aqueous solutions of dispersant at the same time;

[0063] (2) The salt solution, precipitant solution and dispersant aqueous solution are rapidly added to the reactor to carry out co-precipitation reaction. During the rapid formation of crystal nuclei in the co-precipitation process, the addition of dispersant can interfere with the initial arrangement and distribution of Cu and Zn crystal nuclei and increase the specific surface area of ​​the catalyst.

[0064] (3) After aging, filtration, drying and calcination, an ester hydrogenation catalyst is obtained.

[0065] Solution 2:

[0066] (1) Prepare salt solutions and precipitant solutions of Cu and Zn respectively, and prepare aqueous solutions of dispersant at the same time;

[0067] (2) The salt solution and the precipitant solution are quickly added to the reactor to carry out the co-precipitation reaction. The crystal nuclei are quickly formed in the co-precipitation reaction and the aging process is carried out rapidly. During the aging process, the dispersant aqueous solution is gradually added and the pH value is adjusted to effectively intervene in the size of the crystal nuclei as they grow.

[0068] (3) After aging, the catalyst for ester hydrogenation is obtained by filtration, drying and calcination.

[0069] The concentration of the salt solution involved in this application is 0.001-10 mol / L, and the concentration of the precipitant is 0.001-10 mol / L. The salt solution is one or more of nitrates, sulfates, carbonates, chlorides, acetates, etc.; the precipitant is one or more of sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium hydroxide, ammonia, ammonium carbonate, etc.

[0070] The dispersants involved in this application are one or more of cationic surfactants and hydrophilic nonionic surfactants, including hydrophilic cationic surfactants such as amine salts, quaternary ammonium salts, nitrogen benzene and imidazoline, and hydrophilic nonionic surfactants such as polyethylene glycol type, fatty alcohol amide type and polyol type.

[0071] The temperature range of the reaction process involved in this application is 50-100℃, preferably 65-85℃.

[0072] The stirring speed involved in this application is 0-1000 rpm, preferably 200-800 rpm.

[0073] The pH range of the solution in the reaction process involved in this application is between 6.5 and 9.5, preferably between 7.0 and 9.0.

[0074] The reaction time involved in this application is 0.01-600 min, preferably 0.01-10 min.

[0075] The aging process involved in this application has a temperature range of 50-100℃, preferably 65-85℃.

[0076] The stirring speed of the solution during the aging process involved in this application is 0-1000 rpm, preferably 200-800 rpm.

[0077] The beneficial effects that this application can produce include:

[0078] 1) An ester hydrogenation catalyst provided in this application. The catalyst is an alloy catalyst with small particle size, high dispersion, strong anti-sintering performance, and good catalytic activity. When used for the hydrogenation of esters to produce lower alcohols, the reaction conditions are relatively mild, the hydrogen-ester ratio is low, the feed conversion rate is high, and the product selectivity is high.

[0079] 2) A method for preparing an ester hydrogenation catalyst provided in this application. Adding a dispersant during co-precipitation and aging not only helps to form ordered structures of different metals and increase the specific surface area of ​​the catalyst, but also promotes crystal growth and improves the ester hydrogenation performance of the catalyst.

[0080] 3) The application of the ester hydrogenation catalyst provided in this application: when the catalyst is used for the catalytic hydrogenation of MAc, the conversion rate of methyl acetate reaches 99.3% and the selectivity of ethanol reaches 57.9%; when the catalyst is used for the catalytic hydrogenation of DMO, the conversion rate of DMO reaches 96.38% and the selectivity of EG reaches 95.83%. Detailed Implementation

[0081] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0082] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0083] Unless otherwise specified, use conventional testing methods or the testing methods recommended by the instrument.

[0084] In the examples and comparative examples, the evaluation process (1) of the catalyst in the catalytic hydrogenation of methyl acetate to ethanol is as follows:

[0085] An appropriate amount of catalyst powder was pressed into flakes at 30 MPa, crushed, and sieved to obtain catalyst particles of 20–60 mesh for evaluation. 5.0 g of the prepared catalyst was loaded into the isothermal section of the reaction tube. A thermocouple was placed in the center of the catalyst bed, and the airtightness was checked at 5.0 MPa before proceeding with the hydrogenation reaction. Under normal pressure, the hydrogen flow rate was adjusted to 10 ml / min and the nitrogen flow rate to 120 ml / min. At room temperature, the temperature was first increased to 280 °C at 5 °C / min to reduce the catalyst. After holding at this temperature for 2 hours, the temperature was lowered to 220 °C to prepare for the reaction. Methyl acetate was pumped in using a constant flow pump at a specific mass hourly space velocity (MHSV). The MHSV was then vaporized through an isothermal pipeline and mixed with hydrogen before entering the reactor through an insulated line. The mixed reaction gas was then analyzed online by a gas chromatograph via an isothermal pipeline.

[0086] The catalyst activity evaluation calculations are as follows:

[0087]

[0088]

[0089] x represents different products. The target product of MAc hydrogenation is ethanol (EtOH), and the main byproducts are methanol (MeOH) and ethyl acetate (EA).

[0090] The evaluation process (2) of the catalyst in the catalytic hydrogenation of dimethyl oxalate (DMO) to ethylene glycol (EG) is as follows:

[0091] 5.0g of 20-60 mesh catalyst was loaded into the isothermal section of the reaction tube. After inserting a thermocouple and checking the airtightness, the catalyst was reduced in situ. The airtightness was checked, and the operation and reduction conditions were the same as in the evaluation process (1). After reduction, the temperature was lowered to 220℃ for reaction. The reaction was carried out by a constant flow pump at a space velocity of 0.6h. -1 DMO was pumped into a hydrogenation unit and mixed with H2 in a thermostatic pipeline before entering a fixed-bed reactor. The reaction was carried out at 3.5 MPa. The resulting gas mixture was analyzed online by a gas chromatograph equipped with a flame ionization detector (FID). The conversion rate X of dimethyl oxalate was then determined. DMO The selectivity S of a certain product x x Calculated using the following formula:

[0092]

[0093]

[0094] Comparative Example 1

[0095] A certain amount of copper nitrate and zinc nitrate were dissolved in deionized water to prepare a 1.5 mol / L mixed metal salt solution, which served as the salt solution. A certain mass of sodium carbonate was dissolved in deionized water to prepare a 1.5 mol / L solution, which served as the precipitant solution. Using a horizontal flow pump, the sodium carbonate solution and the metal nitrate solution were added separately to a 1 L beaker at a rate of 50 ml / min for a total of 5 min. The pH of the mixed solution was maintained between 7 and 9. The reaction temperature was approximately 70℃, and the beaker was stirred at 500 rpm. The aging temperature was approximately 75℃, and the total aging time was 200 min. After aging, the mixture was filtered, and the filter cake was washed until no Na was detectable in the filtrate. + To date, the filter cake was placed in a 120℃ oven for 20 hours, and then the sample was calcined in a 350℃ muffle furnace for 6 hours. Catalyst CO was prepared, and the evaluation results are shown in Table 1.

[0096] Comparative Example 2

[0097] The experimental procedure was the same as in Example 1, except that the dispersant in 10 ml of a 3% aqueous solution of polyethylene glycol was replaced with sodium carboxymethyl cellulose. Catalyst preparation.

[0098] A certain amount of copper nitrate and zinc nitrate were dissolved in deionized water to prepare a 1.5 mol / L mixed metal salt solution, which served as the salt solution. A certain mass of sodium carbonate was dissolved in deionized water to prepare a 1.5 mol / L solution, which served as the precipitant solution. 10 ml of a 3% aqueous solution of sodium carboxymethyl cellulose was added. Using a horizontal flow pump, the two solutions were added separately to a 1 L beaker at a rate of 50 ml / min and mixed for a total of 5 min. The pH of the mixed solution was maintained between 7 and 9. The reaction temperature was approximately 70°C, and the beaker stirring speed was 500 rpm. The aging temperature was approximately 75°C, and the reaction time was 200 min. After aging, the mixture was filtered, and the filter cake was washed until no Na was detectable in the filtrate. + To date, the filter cake was placed in a 120℃ oven for 20 hours, and then the sample was calcined in a 350℃ muffle furnace for 6 hours. Catalyst CO0 was prepared, and the evaluation results are shown in Table 2.

[0099] Example 1

[0100] A certain amount of copper nitrate and zinc nitrate were dissolved in deionized water to prepare a 1.5 mol / L mixed metal salt solution, which served as the salt solution. A certain mass of sodium carbonate was dissolved in deionized water to prepare a 1.5 mol / L solution, which served as the precipitant solution. 10 ml of a 3% aqueous solution of polyethylene glycol was added. Using a horizontal flow pump, the two solutions were added separately to a 1 L beaker at a rate of 50 ml / min and mixed for a total of 5 min. The pH of the mixed solution was maintained between 7 and 9. The reaction temperature was approximately 70°C, and the beaker stirring speed was 500 rpm. The aging temperature was approximately 75°C, and the reaction time was 200 min. After aging, the mixture was filtered, and the filter cake was washed until no Na was detectable in the filtrate. + To date, the filter cake was placed in a 120℃ oven for 20 hours, and then the sample was calcined in a 350℃ muffle furnace for 6 hours. Catalyst C1 was prepared, and the evaluation results are shown in Table 1.

[0101] Example 2

[0102] A certain amount of copper nitrate and zinc nitrate were dissolved in deionized water to prepare a 1.5 mol / L mixed metal salt solution, which served as the salt solution. A certain mass of sodium carbonate was dissolved in deionized water to prepare a 1.5 mol / L solution, which served as the precipitant solution. 20 ml of 3% tetrapropylammonium hydroxide and N,N-dimethylformamide (DMF) solution were added. The two solutions were added separately to a 1 L beaker using a horizontal flow pump at a rate of 50 ml / min, and the mixture was fed for a total of 5 min. The pH of the mixed solution was maintained between 7 and 9. The reaction temperature was approximately 70°C, and the beaker stirring speed was 500 rpm. The aging temperature was approximately 75°C, and the reaction time was 200 min. After aging, the mixture was filtered, and the filter cake was washed until no Na was detectable in the filtrate. + To date, the filter cake was placed in a 120℃ oven for 20 hours, and then the sample was calcined in a 350℃ muffle furnace for 6 hours. Catalyst C2 was prepared, and the evaluation results are shown in Table 1.

[0103] Example 3

[0104] A certain amount of copper nitrate and zinc nitrate were dissolved in deionized water to prepare a 1.5 mol / L mixed metal salt solution, which served as the salt solution. A certain mass of sodium carbonate was dissolved in deionized water to prepare a 1.5 mol / L solution, which served as the precipitant solution. Using a horizontal flow pump, the sodium carbonate solution and the metal nitrate solution were added separately to a 1 L beaker at a rate of 50 ml / min. The pH of the mixed solution was maintained between 7 and 9. The reaction temperature was approximately 70°C, and the beaker was stirred at 500 rpm for a total feeding time of 5 min. Afterward, an aging process was initiated, and 10 ml of a 3% octadecyltrimethylammonium chloride aqueous solution was added to the mixture. The aging temperature was approximately 75°C, and the aging time was 200 min. After aging, the mixture was filtered, and the filter cake was washed until no Na was detectable in the filtrate. +To date, the filter cake was placed in an oven at 120℃ for 20 hours, and then the sample was calcined in a muffle furnace at 350℃ for 6 hours. Catalyst C3 was prepared, and the evaluation results are shown in Table 1.

[0105] Example 4

[0106] A certain amount of copper nitrate and zinc nitrate were dissolved in deionized water to prepare a 1.5 mol / L mixed metal salt solution, which served as the salt solution. A certain mass of sodium carbonate was dissolved in deionized water to prepare a 1.5 mol / L solution, which served as the precipitant solution, and 10 ml of n-butanol solution was added. Using a horizontal flow pump, the two solutions were added separately to a 1 L beaker at a rate of 50 ml / min and mixed for a total of 5 min. The pH of the mixed solution was maintained between 7 and 9. The reaction temperature was approximately 70°C, the beaker stirring speed was 500 rpm, and the aging temperature was approximately 75°C for a total duration of 200 min. After aging, the mixture was filtered, and the filter cake was washed until no Na was detectable in the filtrate. + To date, the filter cake was placed in a 120℃ oven for 20 hours, and then the sample was calcined in a 350℃ muffle furnace for 6 hours. Catalyst C4 was prepared, and the evaluation results are shown in Table 2.

[0107] Example 5

[0108] A certain amount of copper nitrate and zinc nitrate were dissolved in deionized water to prepare a 1.5 mol / L mixed metal salt solution, which served as the salt solution. A certain mass of sodium carbonate was dissolved in deionized water to prepare a 1.5 mol / L solution, which served as the precipitant solution. Using a horizontal flow pump, the sodium carbonate solution and the metal nitrate solution were added separately to a 1 L beaker at a rate of 50 ml / min. The pH of the mixed solution was maintained between 7 and 9. The reaction temperature was approximately 70°C, and the beaker was stirred at 500 rpm for a total feeding time of 5 min. Afterward, an aging process was initiated, in which 2 g of benzoic acid was added to the mixture. The aging temperature was approximately 75°C, and the aging time was 200 min. After aging, the mixture was filtered, and the filter cake was washed until no Na was detectable in the filtrate. + To date, the filter cake was placed in a 120℃ oven for 20 hours, and then the sample was calcined in a 350℃ muffle furnace for 6 hours. Catalyst C5 was prepared, and the evaluation results are shown in Table 2.

[0109] Example 6

[0110] The experimental procedure was the same as in Example 1, except that 10 ml of a 3% aqueous solution of polyethylene glycol was added to the mixture during aging. Catalyst preparation was then carried out.

[0111] A certain amount of copper nitrate and zinc nitrate were dissolved in deionized water to prepare a 1.5 mol / L mixed metal salt solution, which served as the salt solution. A certain mass of sodium carbonate was dissolved in deionized water to prepare a 1.5 mol / L solution, which served as the precipitant solution. 10 ml of a 3% aqueous solution of polyethylene glycol was added. Using a horizontal flow pump, the two solutions were added separately to a 1 L beaker at a rate of 50 ml / min. The pH of the mixed solution was maintained between 7 and 9. The reaction temperature was approximately 70°C, and the beaker was stirred at 500 rpm for a total feeding time of 5 min. Afterward, an aging process was initiated, with another 10 ml of a 3% aqueous solution of polyethylene glycol added. The aging temperature was approximately 75°C, and the process lasted for a total of 200 min. After aging, the filter cake was washed until no Na was detectable in the filtrate. + To date, the filter cake was placed in a 120℃ oven for 20 hours, and then the sample was calcined in a 350℃ muffle furnace for 6 hours. Catalyst C6 was prepared, and the evaluation results are shown in Table 1.

[0112] Example 7

[0113] The experimental procedure was the same as in Example 1, except that the order of adding 10 ml of a 3% aqueous solution of polyethylene glycol as a dispersant was changed; that is, 10 ml of a 3% aqueous solution of polyethylene glycol was only added during aging. Catalyst preparation was then carried out.

[0114] A certain amount of copper nitrate and zinc nitrate were dissolved in deionized water to prepare a 1.5 mol / L mixed metal salt solution, which served as the salt solution. A certain mass of sodium carbonate was dissolved in deionized water to prepare a 1.5 mol / L solution, which served as the precipitant solution. Using a horizontal flow pump, the sodium carbonate solution and the metal nitrate solution were added separately to a 1 L beaker at a rate of 50 ml / min. The pH of the mixed solution was maintained between 7 and 9. The reaction temperature was approximately 70°C, and the beaker was stirred at 500 rpm for a total feeding time of 5 min. Afterward, an aging process was initiated, adding 10 ml of a 3% aqueous solution of polyethylene glycol. The aging temperature was approximately 75°C, and the aging time was 200 min. After aging, the filter cake was washed until no Na was detectable in the filtrate. + To date, the filter cake was placed in a 120℃ oven for 20 hours, and then the sample was calcined in a 350℃ muffle furnace for 6 hours. Catalyst C7 was prepared, and the evaluation results are shown in Table 1.

[0115] Table 1. Results of the effect of different dispersants on the performance of copper-zinc based catalysts in MAc catalytic hydrogenation.

[0116]

[0117] Table 2. Results of the reaction of different dispersants on copper-zinc based catalysts for the catalytic hydrogenation of DMO.

[0118] Example 4 C4 220 94.26 91.24 Example 5 C5 220 96.38 95.83 Comparative Example 2 C00 220 77.56 88.47

[0119] Table 3. Effects of different dispersants on the specific surface area and pore structure of copper-zinc based catalysts.

[0120]

[0121] *Grain size is calculated using the Scherrer formula based on XRD data.

[0122] As can be seen from Comparative Example 1 and Example 1, adding a dispersant during the precipitation process can significantly increase the specific surface area and dispersion of the catalyst, thereby further improving the catalytic performance.

[0123] As can be seen from Comparative Example 2 and Example 4, different types of dispersants affect the specific surface area and dispersion of the catalyst. That is, surfactants as dispersants can significantly improve the specific surface area and dispersion of the catalyst, thereby further enhancing the catalytic performance.

[0124] As can be seen from Examples 1 and 7, the order in which the dispersant is added affects the specific surface area and dispersion of the catalyst. That is, adding the dispersant during aging can significantly increase the specific surface area and dispersion of the catalyst, thereby further improving the catalytic performance.

[0125] As can be seen from Examples 1 and 6, the addition of dispersants during precipitation and aging can significantly increase the specific surface area and dispersion of the catalyst, thereby further improving its catalytic performance.

[0126] 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 the catalytic hydrogenation of methyl acetate to ethanol, characterized in that, Use an ester hydrogenation catalyst; The ester hydrogenation catalyst comprises CuO and ZnO; The molar ratio of CuO to ZnO is 5:1 to 1:5; The specific surface area of ​​the ester hydrogenation catalyst is 119-120 m². 2 / g; The pore volume of the ester hydrogenation catalyst is 0.7000-0.9500 ml / g; The CuO has a particle size of 7.5-8.5 nm; The ZnO has a particle size of 9.0-11.0 nm; The preparation method of the ester hydrogenation catalyst includes the following steps: S1. The intermediate product is obtained by precipitating a mixture containing Cu source, Zn source and precipitant. S2. A solution containing a dispersant is added to the intermediate product, and the product is aged, filtered, dried, and calcined to obtain the ester hydrogenation catalyst.

2. The method for catalytic hydrogenation of methyl acetate to ethanol according to claim 1, characterized in that, The Cu source and the Zn source are independently selected from at least one of their respective nitrates, sulfates, chlorides, and acetates; The precipitant is selected from at least one of sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium hydroxide, ammonia, and ammonium carbonate.

3. The method for catalytic hydrogenation of methyl acetate to ethanol according to claim 1, characterized in that, The dispersant is selected from at least one of hydrophilic cationic surfactants and hydrophilic nonionic surfactants.

4. The method for catalytic hydrogenation of methyl acetate to ethanol according to claim 3, characterized in that, The hydrophilic cationic surfactant includes ammonium salts and quaternary ammonium salts; The hydrophilic nonionic surfactants include polyethylene glycol type, fatty alcohol amide type, and polyol type.

5. The method for catalytic hydrogenation of methyl acetate to ethanol according to claim 1, characterized in that, In the mixture, the concentrations of the Cu source and the Zn source are 0.001-10 mol / L; The concentration of the precipitant is 0.001-10 mol / L.

6. The method for catalytic hydrogenation of methyl acetate to ethanol according to claim 1, characterized in that, The conditions for precipitation are as follows: The temperature is 50-100 ℃; During precipitation, the pH value is 6.5-9.

5.

7. The method for catalytic hydrogenation of methyl acetate to ethanol according to claim 1, characterized in that, The conditions for aging are as follows: The temperature is 50-100 ℃; The time is 0.5-10 hours; Stirring is performed during the aging process; The stirring speed is 0-1000 rpm, not 0.

8. The method for catalytic hydrogenation of methyl acetate to ethanol according to claim 1, characterized in that, The preparation method of the ester hydrogenation catalyst includes the following steps: B1. Prepare salt solutions containing Cu source, salt solutions containing Zn source, aqueous solutions containing precipitant, and aqueous solutions containing dispersant, respectively. B2. A salt solution containing Cu, a salt solution containing Zn, and an aqueous solution containing a precipitant are added to a reactor for co-precipitation. At the beginning of precipitate formation and aging, an aqueous solution containing a dispersant is added. After aging, filtration, drying, and calcination, the ester hydrogenation catalyst is obtained.

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