A hydroxy ester selective hydrogenation catalyst and a method for preparing the same

Abstract

This invention provides a selective hydrogenation catalyst for hydroxy esters and its preparation method. The catalyst comprises an active component Cu and an auxiliary component X. n+ Metal, carrier, and surface alkalinity regulating agent; the X n+ The metal is one or more of Al, Zn, Ho, Ga, Y, Ce, and In; the support is a composite of SiO2 and ZrO2; the surface alkalinity regulating agent is one or two of phosphotungstic acid, phosphomolybdic acid, silicotungstic acid, silicotomolybdic acid, zirconium hydrogen phosphate, HZSM-5, and Hβ acidic molecular sieves; the mass percentages of each component of the catalyst are as follows: active component oxide CuO 30-70 wt%, and auxiliary component oxide XO n / 2 The catalyst contains 3-20 wt% SiO2 and 15-65 wt% support, with a SiO2 to ZrO2 mass ratio of 0.5-10:1, and 0.2%-5 wt% surface alkalinity regulating agent. The catalyst prepared by this invention is beneficial for generating highly dispersed copper silicate species and improving the activity of Cu. 0 The improved dispersibility enhances the surface Lewis acidity sites while reducing the surface basicity sites, resulting in excellent hydroxy ester hydrogenation activity, selectivity, and stability of the catalyst, demonstrating promising prospects for industrial applications.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology and relates to a hydrogenation catalyst and its preparation method, specifically to a selective hydrogenation catalyst for hydroxy esters and its preparation method. Background Technology

[0002] Diols are alcohol compounds containing two hydroxyl groups within their molecules, such as ethylene glycol, propylene glycol, and bisphenol A. They are mainly used as monomers for polyesters and polyurethanes, as well as solvents, antifreeze agents, and protective agents. They can also be used in pharmaceutical synthesis or as intermediates in organic synthesis, and the demand for them is enormous.

[0003] Selective hydrogenation of hydroxy esters is an important method for synthesizing diols. Currently, copper-based catalysts are the most widely studied and reported class of catalysts for the hydrogenation of hydroxy esters to diols. For example, Chinese patent CN102941094 discloses a catalyst prepared by impregnation, consisting of a main metal Cu, auxiliary metals Ni, Mn, or Co, and a support, applied to the hydrogenation of methyl glycolate to ethylene glycol. This catalyst requires high temperatures of 220-290℃ to exhibit high conversion and selectivity. At high temperatures, active copper is prone to sintering and growth, which is detrimental to the long-life stability of the catalyst. Chinese patent CN101195558A discloses a method for the hydrogenation of methyl 3-hydroxypropionate to 1,3-propanediol using CuO-SiO2 as a catalyst. The conversion rate of methyl 3-hydroxypropionate can reach up to 97.8%, and the selectivity of 1,3-propanediol can reach up to 93.4%. However, it is difficult to obtain high selectivity at high conversion rates, and the catalyst has poor stability and is prone to sintering and deactivation. Patent CN103721734A discloses a CuO-SiO2 catalyst containing Mn, Mo, and P additives for the hydrogenation of methyl 3-hydroxypropionate, achieving a conversion rate greater than 99% and a 1,3-propanediol yield of up to 85%. However, the production efficiency is low, with a feed mass hourly space velocity of only 0.12 h⁻¹. -1The hydrogen-to-ester ratio is as high as 250:1, resulting in high energy consumption for hydrogen circulation and a lack of results regarding long-term catalyst stability. Patent CN114054034A discloses a CuO-Co3O4-Fe2O3-supported composite metal oxide prepared by precipitation-gel method, followed by Ga impregnation on the catalyst surface for modification. Although this catalyst exhibits high reactivity and selectivity in the hydrogenation of 3-hydroxypropionate to 1,3-propanediol, the room-temperature precipitation process leads to uneven dispersion of the active copper precursor, resulting in an average Cu size approaching or exceeding 7 nm after reduction and activation. Furthermore, the interaction between the active metal and the support is insufficient, leading to poor long-term catalyst stability; deactivation occurs after 200 hours of stable operation in a fixed-bed reactor. Patent CN102626638A discloses a copper-based catalyst prepared by conventional precipitation or impregnation methods for the hydrogenation of methyl 2-hydroxypentanoate to 1,2-pentanediol. This catalyst exhibits low activity, with a feed space velocity ≤0.1 h⁻¹. -1 Only then can a high conversion rate be achieved.

[0004] To address the issue of copper catalysts being prone to deactivation through calcination and reduction at high temperatures or sintering, current methods primarily rely on additives to modify the catalysts and improve their hydrogenation performance in hydroxy esters. However, no breakthrough has yet been achieved. Hydroxy ester hydrogenation catalysts suitable for industrial applications must meet the demands of long-life stability, high conversion rates, and high selectivity. Improving the stability of copper-based hydrogenation catalysts requires not only reducing the agglomeration of copper particles during the reaction but also enhancing the interaction between the metal and the support, thereby maintaining the catalyst's hydrogenation activity while simultaneously improving its stability. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a selective hydrogenation catalyst for hydroxy esters and its preparation method. This method synthesizes a more efficient and stable nano-copper-based hydrogenation catalyst by controlling the preparation conditions. This catalyst is mainly used in the hydrogenation of hydroxy esters to prepare diols, enabling the high conversion rate and high activity of hydroxy esters to diols under relatively mild reaction conditions.

[0006] The present invention adopts the following technical solution:

[0007] A selective hydrogenation catalyst for hydroxy esters includes a main active component (CuO) and an auxiliary agent X. n+ Metal, carrier, and surface alkalinity regulating agent, with the following mass percentages: CuO 30-70wt%, and additive component XO. n / 2 3-20 wt%, carrier 15-65 wt% (of which the mass ratio of SiO2 to ZrO2 is 0.5-10:1), and surface alkalinity regulating agent 0.2-5 wt%.

[0008] The X n+ The metal is one or more of Al, Zn, Ho, Ga, Y, Ce, and In.

[0009] The support is a composite of SiO2 and ZrO2.

[0010] The surface alkalinity regulating agent is one or two of phosphotungstic acid, phosphotomolybdic acid, silicotungstic acid, silicotomolybdic acid, zirconium hydrogen phosphate, HZSM-5, and Hβ acidic molecular sieve.

[0011] The preparation method of the hydrogenation catalyst for this hydroxy ester is as follows:

[0012] (1). Mix the main active component, copper precursor, and auxiliary agent X in proportion. n+ The metal precursor was prepared into a mixed aqueous solution A of metal salts, with a molar concentration of 0.1 mol / L to 1 mol / L;

[0013] (2). Alkaline solution and organic amine are mixed to prepare precipitant solution B. The molar concentration of alkaline solution is 0.5mol / L-5mol / L. The molar ratio of copper precursor and organic amine obtained in (1) is 20:1-5:1.

[0014] (3). Nano silica sol or nano silica powder, nano zirconium sol or nano zirconium powder are mixed with water to prepare a carrier solution C;

[0015] (4) Under stirring conditions, the mixed aqueous solution of metal salt A, precipitant solution B and carrier solution C are flowed into a frozen aqueous solution of organic polyol for low-temperature co-precipitation.

[0016] (5) The precipitated slurry is heated to 90-120℃ for high-temperature aging for 4-12 hours. After aging, it is filtered, washed, dried, calcined, and pulverized to obtain catalyst dry powder.

[0017] (6) Weigh 0.2%-5% of the dry powder weight of surface alkaline conditioning agent, weigh 5%-40% of the dry powder weight of adhesive, weigh 1%-5% of the dry powder weight of extrusion aid and mix them evenly with the dry powder.

[0018] (7) Weigh 1%-8% of the dry powder as organic or inorganic acid, add deionized water to prepare an acrylate adhesive solvent, add it to the material in step (6), and knead it evenly.

[0019] (8) The material obtained in step (7) is extruded, dried, calcined and reduced to activate it to obtain a highly active hydrogenation catalyst.

[0020] Furthermore, the catalyst active component described in (1) is a soluble copper nitrate or sulfate, and the auxiliary agent is a soluble metal nitrate or sulfate.

[0021] Furthermore, in (2), the organic amine is ethylamine, propylamine, butylamine or diethylamine, with diethylamine or ethylenediamine being the most preferred.

[0022] Furthermore, the alkaline substance described in (2) is sodium hydroxide, sodium bicarbonate, or sodium carbonate, with sodium hydroxide being the most preferred.

[0023] Furthermore, the organic polyol mentioned in (4) is ethylene glycol, 1,2-propanediol, glycerol, glucose, sucrose, sorbitol or cyclodextrin, with ethylene glycol being the most preferred.

[0024] Furthermore, the surface alkalinity regulating agent mentioned in (6) is selected from one or two of acidic molecular sieves such as phosphotungstic acid, phosphotungstic acid, silicotungstic acid, silicotungstic acid, zirconium hydrogen phosphate, or HZSM-5 and Hβ.

[0025] Furthermore, the low temperature mentioned in (4) is -10-5℃.

[0026] Furthermore, in (5), the drying process is carried out under normal pressure at a temperature of 90-120℃.

[0027] Furthermore, the calcination temperature described in (5) is 400℃-700℃, and the calcination time is 3-8 hours in an air atmosphere.

[0028] Furthermore, the reducing atmosphere described in (8) is high-purity hydrogen or a hydrogen-nitrogen mixture at atmospheric pressure of -9.0 MPa for 6-20 hours.

[0029] Furthermore, the hydroxy esters mainly refer to α-hydroxy esters and β-hydroxy esters.

[0030] The beneficial effects of this invention are:

[0031] 1. The catalyst of this invention is prepared by low-temperature co-precipitation and high-temperature aging. Low-temperature precipitation avoids the instantaneous exothermic reaction that could cause agglomeration of active metal particles, resulting in higher dispersibility of the active and auxiliary components. High-temperature aging, promoted by organic amines, generates highly dispersed copper silicate species, further improving the dispersibility and thermal stability of Cu, while also enhancing Cu… + / Cu 0 The ratio is beneficial for the adsorption and activation of ester carbonyl groups and hydrogenation conversion.

[0032] 2.X n+ The introduction of metal additives can, on the one hand, disperse and stabilize the active metal Cu and promote the reduction of copper species. On the other hand, the oxide particles form oxygen vacancies at the interface with nano-Cu, which can increase the Lewis acid sites on the catalyst surface and thus promote the adsorption, activation and hydrogenation conversion of ester carbonyl groups.

[0033] 3. Adding a surface alkaline regulating agent during catalyst molding can neutralize residual Na from the catalyst preparation process. + The resulting basic sites reduce the dehydration property of hydroxyl groups, decrease the occurrence of dehydration side reactions, and thus improve the selectivity of the target product.

[0034] 4. Compared with single-unit SiO2 supports, the use of SiO2-ZrO2 composite supports can significantly improve the catalyst structure and anti-sintering stability, thereby improving the long-life stability of the catalyst.

[0035] 5. This catalyst exhibits excellent hydrogenation activity, selectivity, and stability in the hydrogenation of hydroxy esters to prepare diols, which is beneficial for reducing energy consumption, reducing by-product formation, and improving production efficiency. Attached Figure Description

[0036] Figure 1 This is a graph showing the results of the fixed-bed hydrogenation stability evaluation of the catalyst in Example 8;

[0037] Figure 2 This is a flowchart illustrating the catalyst preparation process of the present invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0039] The following examples were conducted in a continuous flow fixed-bed reactor, and qualitative and quantitative analyses were performed using gas chromatography at an injector temperature of 260°C and a detector temperature of 280°C. Conversion and selectivity were calculated using the internal standard method.

[0040] Example 1:

[0041] like Figure 2As shown, weigh 27.35g of copper nitrate trihydrate, 2.2g of zinc nitrate hexahydrate, 4.41g of aluminum nitrate nonahydrate, and 0.7g of anhydrous holmium nitrate, and prepare solution A with 1273ml of deionized water; weigh 11.2g of sodium hydroxide, dissolve it in 560ml of deionized water, and then add 0.46g of ethylenediamine to prepare solution B; weigh 21.7g of 30% silica sol and 43.3g of 30% zirconium sol, and dilute them with 650g of deionized water to prepare solution C. 100 ml of deionized water and 8.45 g of sucrose were added to a reaction vessel, and the temperature was lowered to 0 °C and maintained at a constant temperature. Solutions A, B, and C were fed into the reaction vessel concurrently to co-precipitate. After precipitation, the temperature was raised to 120 °C and aged for 6 h. The solution was washed with deionized water until the filtrate was neutral, dried at 110 °C for 24 h, and calcined at 500 °C for 4 h to obtain the catalyst precursor 30CuO2ZnO2Al2O31Ho2O3 / 21.7SiO243.3ZrO2. 30 g of catalyst precursor powder, 0.3 g of Tianqing powder, 1.5 g of pseudoboehmite, and 0.09 g of phosphotungstic acid were added, kneaded thoroughly with 5% dilute nitric acid, extruded into strips, dried at 90 °C for 24 h, and calcined at 600 °C for 4 h. The strips were sieved into 20-40 mesh particles for catalyst performance evaluation.

[0042] 4g of catalyst was weighed and loaded into the isothermal section of a tubular fixed-bed reactor, with the remainder filled with SiC. The catalyst was reduced and activated for 6 hours at 200 mL / min at 250°C under atmospheric pressure and a 20% H2-N2 mixed atmosphere. After the reactor temperature dropped to 155°C, the pressure was increased to 8.0 MPa using high-purity H2, and a 20wt% methyl 3-hydroxypropionate methanol solution was injected into the reactor at a feed mass hourly space velocity (WHSV) of 0.15 h⁻¹. -1 The hydrogen-to-ester ratio was 30:1. Analysis of samples taken after 60 hours of reaction showed a methyl 3-hydroxypropionate conversion rate of 93.9% and a 1,3-propanediol selectivity of 91.5%.

[0043] Example 2

[0044] like Figure 2As shown, 36.47g of copper nitrate trihydrate, 8.83g of aluminum nitrate nonahydrate, and 0.38g of cerium nitrate hexahydrate were weighed and dissolved in 164ml of deionized water to prepare solution A; 14.39g of sodium hydroxide was weighed and dissolved in 120ml of deionized water, and then 2.4g of diethylamine was added to prepare solution B; 8.32g of silica powder and zirconium dioxide powder were weighed and diluted in 166g of deionized water to prepare solution C. 100ml of deionized water and 2.04g of ethylene glycol were added to a reaction vessel, the temperature was lowered to 5℃, and kept constant. Solutions A, B, and C were fed into the reaction vessel concurrently to co-precipitate; after complete precipitation, the temperature was raised to 100℃ and aged for 8h, washed with deionized water until the filtrate was neutral, dried at 100℃ for 24h, and calcined at 550℃ for 4h to obtain the catalyst precursor 40CuO4Al2O30.5CeO2 / 27.75SiO227.75ZrO2. Take 30g of catalyst precursor powder, 0.5g of Tianqing powder, 3g of pseudoboehmite, and 0.06g of tungsten phosphate. Add 1% dilute nitric acid, knead thoroughly, and then extrude into strips. Dry at 90℃ for 24h and calcine at 700℃ for 3h. Sieve into 20-40 mesh particles for catalyst performance evaluation. The catalyst loading and reduction are the same as in Example 1, except that the reduction activation pressure is 6MPaH2 and the time is 6h. After the reactor temperature drops to 150℃, a 10wt% methyl 3-hydroxypropionate methanol solution is injected into the reactor at a feed mass hourly space velocity of 0.15h. -1 The hydrogen-to-ester ratio was 30:1. Analysis of samples taken after 60 hours of reaction showed a methyl 3-hydroxypropionate conversion rate of 98.1% and a 1,3-propanediol selectivity of 89.3%.

[0045] Example 3

[0046] like Figure 2As shown, 59.26g of copper nitrate trihydrate, 11.03g of aluminum nitrate nonahydrate, and 8.19g of gallium nitrate were weighed and dissolved in 552ml of deionized water to prepare solution A; 24.3g of sodium hydroxide was weighed and dissolved in 304ml of deionized water, and then 3.32g of ethylenediamine was added to prepare solution B; 13.3g of 30% silica sol and 13.6g of 30% zirconium sol were weighed and diluted in 100g of deionized water to prepare solution C. 100 ml of deionized water and 3.32 g of ethylene glycol were added to a reaction vessel, and the temperature was lowered to 5 °C and maintained at a constant temperature. Solutions A, B, and C were fed into the reaction vessel concurrently to co-precipitate. After precipitation, the temperature was raised to 90 °C and aged for 12 h. The solution was washed with deionized water until the filtrate was neutral, dried at 120 °C for 24 h, and calcined at 500 °C for 6 h to obtain the catalyst precursor 65CuO-5Al2O3-10Ga2O3 / 13.3SiO2-6.7ZrO2. 30 g of catalyst precursor powder, 0.9 g of Tianqing powder, 6 g of pseudoboehmite, and 1.0 g of zirconium hydrogen phosphate were added to 8% dilute nitric acid, kneaded thoroughly, extruded into strips, dried at 90 °C for 24 h, and calcined at 600 °C for 4 h. The mixture was then sieved into 20-40 mesh particles for catalyst performance evaluation. The catalyst loading and reduction were the same as in Example 1, except that the reduction activation pressure was 9 MPa and the time was 10 h. After the reactor temperature dropped to 160 °C, high-purity H2 was used to boost the pressure to 9.0 MPa, and a 30 wt% methyl 3-hydroxypropionate methanol solution was injected into the reactor at a feed mass hourly space velocity of 0.25 h⁻¹. -1 The hydrogen-to-ester ratio was 60:1. Analysis of samples taken after 60 hours of reaction showed a methyl 3-hydroxypropionate conversion rate of 93.8% and a 1,3-propanediol selectivity of 90.5%.

[0047] Example 4:

[0048] like Figure 2As shown, weigh 45.58g of anhydrous copper sulfate, 2.19g of zinc sulfate heptahydrate, 8.83g of aluminum sulfate octadecahydrate, and 1.4g of holmium nitrate pentahydrate, and prepare solution A with 416ml of deionized water; weigh 18.43g of sodium hydroxide and dissolve it in 154ml of deionized water, then add 3.05g of diethylamine to prepare solution B; weigh 33.6g of 30% silica sol and 2.52g of zirconium dioxide powder, add 144g of deionized water and stir to dilute to prepare solution C. 100 ml of deionized water and 2.26 g of ethylene glycol were added to a reaction vessel, cooled to 5 °C, and kept at a constant temperature. Solutions A, B, and C were fed into the reaction vessel concurrently to co-precipitate. After complete precipitation, the mixture was heated to 90 °C and aged for 6 h. The solution was washed with deionized water until neutral, dried at 110 °C for 24 h, and calcined at 600 °C for 4 h to obtain the catalyst precursor 50CuO2ZnO4Al2O32Ho2O3 / 33.6SiO28.4ZrO2. 30 g of the catalyst precursor powder, 0.75 g of Tianqing powder, 5 g of pseudoboehmite, and 0.2 g of phosphomolybdic acid were added, kneaded thoroughly with 5% dilute nitric acid, extruded into strips, dried at 90 °C for 24 h, and calcined at 400 °C for 8 h. The resulting particles were sieved into 20-40 mesh particles for catalyst performance evaluation. The catalyst loading and reduction were the same as in Example 1, except that the reduction activation pressure was 8 MPa and the time was 10 h. After the reactor temperature dropped to 170 °C, high-purity H2 was used to boost the pressure to 8.0 MPa, and a 20 wt% methyl 3-hydroxypropionate methanol solution was injected into the reactor at a feed mass hourly space velocity of 0.3 h⁻¹. -1 The hydrogen-to-ester ratio was 80:1. Analysis of samples taken after 60 hours of reaction showed a methyl 3-hydroxypropionate conversion rate of 96.7% and a 1,3-propanediol selectivity of 91.1%.

[0049] Example 5:

[0050] like Figure 2As shown, weigh 54.7g of copper nitrate trihydrate, 1.4g of anhydrous holmium nitrate and 0.65g of indium nitrate, and prepare solution A with 458ml of deionized water; weigh 34.0g of anhydrous sodium carbonate and dissolve it in 213ml of deionized water, then add 3.31g of diethylamine to prepare solution B; weigh 25.3g of 30% silica sol and 11.7g of 30% zirconium sol, and dilute them with 140g of deionized water to prepare solution C. 100 ml of deionized water and 8.15 g of glucose were added to a reaction vessel, cooled to 5 °C, and kept at a constant temperature. Solutions A, B, and C were fed into the reaction vessel concurrently for co-precipitation. After precipitation, the temperature was raised to 100 °C and aged for 4 h. The solution was washed with deionized water until neutral, dried at 110 °C for 24 h, and calcined at 550 °C for 4 h to obtain the catalyst precursor 60CuO2Ho2O31In2O3 / 25.3SiO211.7ZrO2. 30 g of catalyst precursor powder, 0.8 g of Tianqing powder, 8 g of pseudoboehmite, and 1.5 g of Hβ molecular sieve were added to 3% dilute nitric acid, kneaded thoroughly, extruded into strips, dried at 90 °C for 24 h, and calcined at 600 °C for 4 h. The mixture was sieved into 20-40 mesh particles for catalyst performance evaluation. The catalyst loading and reduction were the same as in Example 1, except that the reduction activation time was 20 hours. After the reactor temperature dropped to 160°C, high-purity H2 was used to boost the pressure to 9.0 MPa, and a 20 wt% methyl 3-hydroxypropionate methanol solution was injected into the reactor at a feed mass hourly space velocity of 0.3 h⁻¹. -1 The hydrogen-to-ester ratio was 80:1. Analysis of samples taken after 60 hours of reaction showed a methyl 3-hydroxypropionate conversion rate of 92.8% and a 1,3-propanediol selectivity of 90.5%.

[0051] Example 6:

[0052] like Figure 2As shown, weigh 63.82g of copper nitrate trihydrate, 2.2g of zinc nitrate hexahydrate, 4.4g of aluminum nitrate nonahydrate, and 2.6g of indium nitrate, and prepare solution A with 563ml of deionized water; weigh 24.8g of sodium hydroxide, dissolve it in 124ml of deionized water, and then add 3.12g of n-propylamine to prepare solution B; weigh 18.3g of 30% silica sol and 3.7g of 30% zirconium sol, and dilute them with 110g of deionized water to prepare solution C. 100 ml of deionized water and 15.85 g of ethylene glycol were added to a reaction vessel, and the temperature was lowered to -10 °C. The temperature was maintained at a constant level, and solutions A, B, and C were fed into the reaction vessel concurrently to co-precipitate. After complete precipitation, the temperature was raised to 90 °C and aged for 6 h. The precipitate was washed with deionized water until the filtrate was neutral, dried at 110 °C for 24 h, and calcined at 500 °C for 4 h to obtain the catalyst precursor 70CuO2ZnO2Al2O34In2O3 / 18.3SiO23.7ZrO2. 30 g of catalyst powder, 1.5 g of Tianqing powder, 12 g of pseudoboehmite, and 0.3 g of phosphotungstic acid were taken, and after thorough kneading with 3% acetic acid, the mixture was extruded into strips, dried at 90 °C for 24 h, and calcined at 500 °C for 4 h. The mixture was then sieved into 20-40 mesh particles for catalyst performance evaluation. The catalyst loading and reduction were the same as in Example 1. After the reactor temperature dropped to 165°C, the pressure was increased to 9.0 MPa using high-purity H2, and a 50 wt% methyl 3-hydroxypropionate methanol solution was injected into the reactor at a feed mass hourly space velocity of 0.5 h⁻¹. -1 The hydrogen-to-ester ratio was 120:1. Analysis of samples taken after 60 hours of reaction showed a methyl 3-hydroxypropionate conversion rate of 96.2% and a 1,3-propanediol selectivity of 88.1%.

[0053] Example 7:

[0054] like Figure 2As shown, weigh 50.14g of copper nitrate trihydrate, 3.29g of zinc nitrate hexahydrate, 1.1g of aluminum nitrate nonahydrate, and 1.02g of yttrium nitrate hexahydrate, and prepare solution A with 743ml of deionized water; weigh 19.6g of sodium hydroxide and dissolve it in 490ml of deionized water, then add 3.03g of ethylenediamine to prepare solution B; weigh 26g of 30% silica sol and 14g of 30% zirconium sol, and dilute them with 200g of deionized water to prepare solution C. 100 ml of deionized water and 2.49 g of ethylene glycol were added to a reaction vessel, and the temperature was lowered to 5 °C. The temperature was maintained at a constant level, and solutions A, B, and C were fed into the reaction vessel concurrently to co-precipitate. After complete precipitation, the temperature was raised to 90 °C and aged for 8 h. The precipitate was washed with deionized water until the filtrate was neutral, dried at 110 °C for 24 h, and calcined at 500 °C for 4 h to obtain the catalyst precursor 55CuO3ZnO1Al2O31Y2O3 / 26SiO214ZrO2. 30 g of the catalyst precursor powder, 0.75 g of Tianqing powder, 9 g of pseudoboehmite, 0.1 g of phosphotungstic acid, and 1.0 g of Hβ molecular sieve were added to 5% acetic acid, kneaded thoroughly, extruded into strips, dried at 90 °C for 24 h, and calcined at 600 °C for 4 h. The mixture was then sieved into 20-40 mesh particles for catalyst performance evaluation. The catalyst loading and reduction were the same as in Example 1. After the reactor temperature dropped to 165°C, the pressure was increased to 8.0 MPa using high-purity H2, and a 20 wt% methyl 3-hydroxypropionate methanol solution was injected into the reactor at a feed mass hourly space velocity of 0.2 h⁻¹. -1 The hydrogen-to-ester ratio was 60:1. Analysis of samples taken after 60 hours of reaction showed a methyl 3-hydroxypropionate conversion rate of 97.6% and a 1,3-propanediol selectivity of 90.7%.

[0055] Example 8:

[0056] like Figure 2As shown, weigh 48.32g of copper nitrate trihydrate, 6.62g of aluminum nitrate nonahydrate, 9.82g of gallium nitrate and 3.5g of holmium nitrate pentahydrate, and prepare solution A with 456ml of deionized water; weigh 20.7g of sodium hydroxide and dissolve it in 167ml of deionized water, then add 1.4g of ethylenediamine to prepare solution B; weigh 18g of 30% silica sol and 9g of 30% zirconium sol, and dilute them with 135g of deionized water to prepare solution C. 100 ml of deionized water and 2.74 g of ethylene glycol were added to a reaction vessel, cooled to 5 °C, and kept at a constant temperature. Solutions A, B, and C were fed into the reaction vessel concurrently to co-precipitate. After complete precipitation, the mixture was aged at 90 °C for 6 h. The solution was washed with deionized water until neutral, dried at 100 °C for 24 h, and calcined at 500 °C for 4 h to obtain the catalyst precursor 53CuO3Al2O312Ga2O25Ho2O3 / 18SiO29ZrO2. 30 g of the catalyst precursor powder, 0.8 g of Tianqing powder, 6 g of pseudoboehmite, 0.3 g of phosphotungstic acid, and 1.0 g of Hβ molecular sieve were added to 8% dilute nitric acid, kneaded thoroughly, extruded into strips, dried at 90 °C for 24 h, and calcined at 600 °C for 4 h. The mixture was sieved into 20-40 mesh particles for catalyst performance evaluation. The catalyst loading and reduction were the same as in Example 1. After the reactor temperature dropped to 160°C, the reactor was pressurized to 8.0 MPa using high-purity H2. A 20 wt% methyl 3-hydroxypropionate methanol solution was then pumped into the reactor using a high-pressure pump at a feed mass hourly space velocity (WHSV) of 0.20 h⁻¹. -1 The hydrogen-to-ester ratio was 90:1. After 500 hours of stable reaction operation, the conversion of methyl 3-hydroxypropionate and the selectivity of 1,3-propanediol remained essentially constant at 93.8% and 91.4%, respectively, without significant decrease. Figure 1 As shown in the figure, the catalyst synthesized in this invention exhibits good stability.

[0057] Comparative Example 1:

[0058] The 50CuO2ZnO4Al2O32Ho2O3 / 33.6SiO28.4ZrO2 catalyst precursor was prepared according to the method in Example 4, except that the preparation temperature was 30℃. The catalyst evaluation conditions were the same as in Example 4. After 60 hours of reaction, the sample analysis results showed that the conversion rate of methyl 3-hydroxypropionate was 88.2%, and the selectivity of 1,3-propanediol was 89.6%.

[0059] XRD tests were performed on the catalysts of Example 4 and Comparative Example 1. The Cu particle size of the catalyst in Example 4 was 5.2 nm, and the Cu particle size of the catalyst in Comparative Example 1 was 8.6 nm. The results show that the catalyst prepared under low-temperature conditions avoids the agglomeration of active metal particles caused by the instantaneous exothermic precipitation reaction, resulting in higher dispersion of the active and auxiliary components and thus improving the hydrogenation activity of the catalyst.

[0060] Comparative Example 2:

[0061] The 55CuO3ZnO1Al2O31Y2O3 / 26SiO214ZrO2 catalyst precursor was prepared according to the method in Example 7, the difference being that no surface alkaline regulating agent was added during the molding process. The catalyst evaluation conditions were the same as in Example 7. After 60 hours of reaction, the sample analysis results showed that the conversion rate of methyl 3-hydroxypropionate was 92.3%, and the selectivity of 1,3-propanediol was 82.3%.

[0062] XRD analysis of the catalysts in Example 7 and Comparative Example 2 revealed that the Cu particles of the active catalyst were similar in size (-4.8 nm). Analysis of the catalytic hydrogenation results showed that the surface alkaline modifier could reduce the hydroxyl dehydration activity, decrease the occurrence of dehydration side reactions, and thus improve the selectivity of the target product.

[0063] Comparative Example 3:

[0064] The catalyst precursor 53CuO3Al2O312Ga2O25Ho2O3 / 18SiO29ZrO2 was prepared according to the method in Example 8, the difference being that the organic amine promoter ethylenediamine was not added to the precipitant. The catalyst evaluation conditions were the same as in Example 8. After 60 hours of reaction, the sample analysis results showed that the conversion rate of methyl 3-hydroxypropionate was 90.3%, and the selectivity of 1,3-propanediol was 88.1%.

[0065] XRD analysis of the catalysts in Example 8 and Comparative Example 3 revealed that the Cu particles of the active component were similar in size (-5.4 nm). Analysis of the catalytic hydrogenation results shows that incorporating an organic amine promoter into the precipitant is beneficial for controlling the active species Cu in the catalyst. + / Cu 0 The ratio is adjusted to favor the adsorption and activation of ester carbonyl groups and hydrogenation conversion, thereby improving the catalyst activity and selectivity.

[0066] Example 9:

[0067] The catalyst was prepared and loaded according to Example 8. The catalyst was reduced and activated in 6 MPa H2 at 240 °C for 4 h. The reaction conditions were the same as in Example 8, except that the 20 wt% methyl 3-hydroxypropionate methanol solution was replaced with a 20 wt% methyl glycolate methanol solution. After 60 h of reaction, the sample analysis results showed that the conversion rate of methyl glycolate was 97.2% and the selectivity of ethylene glycol was 99.4%.

[0068] Example 10:

[0069] The catalyst was prepared, loaded, and reduced and activated according to Example 8, except that the 20 wt% methyl 3-hydroxypropionate methanol solution was replaced with a 20 wt% methyl 2-hydroxyvalerate methanol solution. After 60 h of reaction, the sample analysis results showed that the conversion rate of methyl 2-hydroxyvalerate was 98.7% and the selectivity of 1,2-pentanediol was 99.0%.

[0070] As can be seen from the above results, the catalyst synthesized in this invention has high activity, selectivity and stability for both α-hydroxy esters and β-hydroxy esters under relatively mild reaction conditions, and has good prospects for industrial application.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a selective hydrogenation catalyst for hydroxy esters, characterized in that, The preparation method includes the following steps: Step (1). Mix the main active component, copper precursor, and auxiliary agent X in proportion. n+ The metal precursor was prepared as a mixed aqueous solution A of metal salts, wherein the auxiliary agent X n+ The metal is one or more of Al, Zn, Ho, Ga, Y, Ce, and In; Step (2). The alkaline substance is mixed with the organic amine to prepare a precipitant solution B. The molar concentration of the alkaline solution is 0.5 mol / L-5 mol / L. The molar ratio of the copper precursor and the organic amine in step (1) is 20:1-5:

1. The organic amine is one of ethylenediamine, diethylamine and n-propylamine. The alkaline substance is one of sodium hydroxide, sodium bicarbonate and sodium carbonate. Step (3). Mix nano-silica sol or nano-silica powder, nano-zirconium sol or nano-zirconium powder with water to prepare carrier solution C; Step (4). Under stirring conditions, the metal salt mixed aqueous solution A, precipitant solution B and carrier solution C are fed into a frozen aqueous solution containing organic polyol for low-temperature co-precipitation, wherein the low temperature is -10℃ to 5℃. Step (5). The precipitated slurry is heated to 90-120℃ for high-temperature aging for 4-12 hours. After aging, it is filtered, washed, dried, calcined, and pulverized to obtain catalyst dry powder. Step (6). Weigh 0.2%-5% of the dry powder weight of surface alkalinity regulating agent, weigh 5%-40% of the dry powder weight of binder, weigh 1%-5% of the dry powder weight of extrusion aid and mix them evenly with the dry powder. The surface alkalinity regulating agent is selected from one or two of phosphotungstic acid, phosphotomolybdic acid, silicotungstic acid, silicotomolybdic acid, zirconium hydrogen phosphate, HZSM-5, and Hβ acidic molecular sieve. Step (7). Weigh 1%-8% of the dry powder by weight of organic or inorganic acid, add deionized water to prepare a dilute acid-gel solvent, add it to the material in step (6), and knead evenly. Step (8). The material obtained in step (7) is extruded, dried, calcined and reduced to activate it to obtain a highly active hydrogenation catalyst; The support is a composite of SiO2 and ZrO2, wherein the mass ratio of SiO2 to ZrO2 is 0.5-10:

1.

2. The preparation method according to claim 1, characterized in that, The organic polyol mentioned in step (4) is ethylene glycol, 1,2-propanediol, glycerol, glucose, sucrose, sorbitol or cyclodextrin.

3. The preparation method according to claim 1, characterized in that, In step (5), the drying is performed under normal pressure at a temperature of 90-120℃; the calcination temperature in step (5) is 400℃-700℃ for 3-8 hours in air.

4. The preparation method according to claim 1, characterized in that, In step (8), the catalyst precursor is reduced in high-purity hydrogen or a hydrogen-nitrogen mixture at atmospheric pressure -9.0 MPa for 6-20 h.

5. The preparation method according to claim 1, characterized in that, The hydroxy esters refer to α-hydroxy esters and β-hydroxy esters.

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