A catalyst for hydrogenating 3-hydroxypropionic acid methyl ester into 1,3-propanediol, a preparation method and application thereof

Abstract

The present application relates to a kind of 3-hydroxypropionic acid methyl ester hydrogenation 1,3-propanediol catalyst and its preparation method and application.Silica is used as structure carrier, copper is used as active component, and zinc zirconium magnesium oxide is used as auxiliary agent to prepare multi-metal composite catalyst using gel precipitation method.The multi-metal composite catalyst prepared using gel precipitation method has high active metal dispersion, strong metal and carrier binding force, and by introducing magnesium oxide as catalyst structure auxiliary agent, silicon loss during catalyst reaction can be effectively reduced, high yield of 1,3-propanediol is ensured, and excellent structural stability is obtained, so the application prospect is wide.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology and relates to an ester hydrogenation catalyst, specifically a method for preparing a catalyst for the hydrogenation of methyl 3-hydroxypropionate to 1,3-propanediol. Background Technology

[0002] PTT is a promising new type of polyester polymer material developed after polyethylene terephthalate (PET) in the 1950s and polybutylene terephthalate (PBT) in the 1970s. The primary use of 1,3-propanediol is as a monomer in the polymerization of terephthalic acid to produce polypropylene terephthalate (PTT). It is also a raw material for the production of antifreeze agents, antislip agents, plasticizers, cosmetics, and surfactants.

[0003] Currently, there are three main processes for producing 1,3-propanediol: the ethylene oxide hydroformylation hydrogenation method industrialized by Shell in 1996; the acrolein hydration hydrogenation method developed by Degussa in 1995; and the microbial fermentation method, represented by DuPont in the United States. These three methods do not differ significantly in terms of production capacity, but each has its own characteristics: the acrolein hydration hydrogenation method has mild process conditions, relatively low technical difficulty, a mature hydrogenation process, and low equipment requirements; however, the raw material acrolein is highly toxic, flammable, and explosive, making it difficult to store and transport, and it is also costly. The microbial fermentation method is characterized by "green chemistry," utilizing renewable resources, producing a clean environment, with mild reaction conditions, simple operation, and low pollution; however, the product concentration is low, and production efficiency is difficult to improve. Ethylene oxide is abundant and inexpensive, making the ethylene oxide process highly favored. However, the intermediate 3-hydroxypropanal in the ethylene oxide hydroformylation process is extremely unstable, and the catalytic separation technology is complex, requiring a high-pressure reactor (greater than 10 MPa). This results in high equipment requirements, significant overall technical difficulty, and high investment costs. In contrast, the ethylene oxide hydroesterification process produces 1,3-propanediol, generating methyl 3-hydroxypropionate, thus avoiding the formation of 3-hydroxypropanal and representing a new research direction for the ethylene oxide process.

[0004] The preparation of 1,3-propanediol via the hydrogen esterification of ethylene oxide typically involves the selective hydrogenation of the resulting methyl 3-hydroxypropionate after the EO hydrogen esterification reaction. Currently, copper-silica catalyst systems are commonly used in this process. The deactivation of copper-silica catalysts is mainly due to four factors: degradation of active sites, including Cu grain growth due to sintering and Cu… + / Cu 0Imbalance in proportions; damage to the carrier structure, with SiO2 hydrothermal dissolution leading to a decrease in specific surface area and pore collapse, triggering Cu particle migration and sintering; poisoning by impurities such as sulfur and chlorine forming stable compounds with Cu or corroding the carrier; and process factors, such as temperature runaway, improper regeneration, and load fluctuations, which accelerate the above-mentioned degradation processes. Among these, silicon loss and Cu sintering under hydrothermal conditions are often the main coupled causes.

[0005] Silicon loss from copper-silicon catalysts in ester hydrogenation is primarily driven by three factors: hydrothermal dissolution, alcoholysis, and physical exfoliation. Water, a byproduct of the reaction, undergoes reversible dissolution with SiO2 under high temperature and pressure to form silanols, subsequently generating soluble orthosilicic acid or silicates. Alcohols, a byproduct of the reaction, and alcohols in the reaction solvent undergo alcoholysis to generate volatile siloxanes. Meanwhile, amorphous SiO2 supports possess a high specific surface area and a high surface hydroxyl density (>3 OH / nm). 2 Poor chemical stability; capillary condensation in the mesoporous structure allows liquid water to permeate the pores, inducing local hydrothermal stress, leading to fatigue fracture and physical exfoliation of the SiO2 framework. Furthermore, alkali metal impurities (Na...) + K + The formation of soluble silicates, interfacial shear stress generated by Cu particle sintering, and process factors such as temperature fluctuations and load impacts all accelerate the loss. After long-term operation, the specific surface area of ​​the support decreases by 30-60%, triggering the sintering of Cu active centers, ultimately leading to a 15-25% decrease in catalyst activity.

[0006] CN201911191398 detected methyl orthosilicate impurities in the reaction products of Cu / SiO2 catalysts through chromatographic and mass spectrometric analysis, confirming silicon loss from the support. The inventors believe that this byproduct is generated by the reaction of methanol with the silica support, and therefore propose to replace the silica support with titanium-silicon molecular sieves to fundamentally eliminate silicon loss and product contamination.

[0007] CN202010641819, "Highly Efficient Copper-Based Catalyst for the Hydrogenation of Dimethyl Oxalate to Ethylene Glycol and Its Preparation Method," points out that commonly used copper / silica catalysts exhibit "silicon loss" under methanol-containing gas-phase reaction conditions, accelerating the aggregation of copper nanoparticles and affecting the quality of ethylene glycol. This paper utilizes an ordered mesoporous silica support, leveraging the pore confinement effect to suppress the aggregation of copper active components and improve catalytic stability. Under conditions of 200-260℃, 2.0-4.0 MPa, and a hydrogen-to-ester ratio of 50-200, the conversion rate of dimethyl oxalate can reach 99%, and the selectivity of ethylene glycol is >95%. In a methanol-containing gas-phase reaction environment, the silicon loss rate is reduced by more than 50% compared to traditional Cu / SiO2 catalysts; after 1000 hours of long-term operation, the copper grain growth rate is <30%, and the activity decay rate is <8%.

[0008] CN202010286566 A silanized modified copper-silicon catalyst, its preparation method, and its applications. This method involves silanizing a silica support with a silane coupling agent, resulting in alkyl groups covering the silanol groups and reducing the number of basic sites and silanol groups on the surface. This modification not only inhibits byproduct formation but also significantly improves the high stability of the copper-silicon catalyst, indirectly reducing the hydrothermal dissolution loss of silicon species. The selectivity for ethylene glycol or methyl glycolate is increased to 96%. Stability tests show that the modified catalyst maintains 92% activity after 1000 hours of continuous operation under water vapor conditions, with a support surface area decay rate of <15%.

[0009] CN202311709066 employs an ordered polystyrene template to regulate a macroporous silica support, and enhances the structural integrity of the support through secondary organosilicon ester deposition, thereby improving its low-temperature activity and stability. The reaction is carried out at a temperature of 200-240℃, a pressure of 2.0-4.0 MPa, a hydrogen-to-ester molar ratio of 80-150, and a liquid hourly space velocity of 0.5-2.0 h⁻¹. -1 Under these conditions, the conversion rate of dimethyl oxalate can reach 99%, and the selectivity of ethylene glycol is 95%.

[0010] CN201210200684 describes the preparation of a copper-silicon catalyst using the sol-gel method. Following ammonia stripping, the reactivity of dimethyl oxalate and the selectivity for ethylene glycol were improved. The study also indicates that lowering the optimal activity temperature improves stability and indirectly mitigates silicon loss caused by high-temperature hydrothermal treatment. Under reaction conditions of 180-220℃ and 2.0-3.0 MPa, the conversion rate of dimethyl oxalate reached 95%, and the selectivity for ethylene glycol reached 90%.

[0011] The catalyst preparation method proposed in Samsung's US20030069456 patent involves adding an alkaline precipitant to an aqueous solution of copper salt to form Cu(OH)₂ precipitate, then adding colloidal SiO₂, followed by particle aging. This reaction requires relatively harsh conditions; at 165 °C and 10 MPa, a reaction time of 18 h achieves a 3-HPM conversion rate of 80.92% and a 1,3-PDO selectivity of 87%.

[0012] CN102059125 discloses a catalyst for the hydrogenation of methyl 3-hydroxypropionate to 1,3-propanediol. The active components of the catalyst are oxides of Cu, Mn and Zr, and it is prepared by titration with sodium carbonate or sodium hydroxide as an alkaline precipitant. The resulting catalyst has the advantages of high reactivity, good reproducibility and mild conditions.

[0013] CN101020635 discloses a Cu / (TiO2-SiO2) catalyst prepared by impregnation method. The performance was tested in a fixed-bed reactor. Using methanol as solvent, the catalyst achieved a 3-HMP conversion of 93.9% and a 1,3-propanediol selectivity of 88.2% at 140℃ and 7 MPa. When the 3-HMP conversion reached 93.9%, the 1,3-PDO selectivity reached 88.2%. The study on catalyst stability was not mentioned.

[0014] Shell patent US6191321 discloses a method for preparing a copper-zinc-silicon catalyst. In the examples, the reaction is carried out in a reactor using methanol as the solvent, with a liquid hourly space velocity (LHSV) of 1 h⁻¹. -1 Under conditions of 10.3 MPa pressure and 165–190 °C temperature, the conversion rate of 3-HMP can reach 99.6%, and the selectivity of 1,3-propanediol can reach 81.49%. No research on catalyst stability was mentioned.

[0015] Domestic and international patents related to silicon loss in copper silica catalysts mostly address the silicon loss problem in the hydrogenation of dimethyl oxalate. There is a lack of solutions for silicon loss in the hydrogenation of methyl 3-hydroxypropionate to 1,3-propanediol. To address silicon loss, methods often involve replacing the support with a silicon-free substrate and surface hydrophobic / silanization modification to reduce silicon loss. However, these methods may lead to reduced 1,3-propanediol yield and decreased catalyst stability in the hydrogenation of methyl 3-hydroxypropionate to 1,3-propanediol. Summary of the Invention

[0016] Current copper-silica catalysts, especially those for the hydrogenation of methyl 3-hydroxypropionate to 1,3-propanediol, suffer from poor stability due to the lack of Lewis acid sites in the predominantly weakly acidic or neutral silica surface, leading to easy migration and aggregation of copper particles. Furthermore, the catalyst experiences silicon loss during hydrothermal dissolution and alcoholysis, resulting in poor catalyst stability. This invention aims to overcome these shortcomings by providing a method for preparing a catalyst for the hydrogenation of methyl 3-hydroxypropionate to 1,3-propanediol. Specifically, a gel precipitation method is used to introduce a composite metal oxide of ZrO2 and MgO into a copper-zinc-silicon catalyst system. Silicon loss is suppressed through a triple mechanism of chemically stabilized framework, physical barrier against water attack, and optimized surface properties. The goal is to form partial Mg-O-Si bonds, with Mg... 2+In the later stages of the ammonia stripping process, Mg-O bonds react with hydroxyl groups on the SiO2 surface to form ≡Si-O-Mg-O-Si≡ bridging bonds. These bonds have higher energy than Si-O-Si bonds, significantly increasing the network structure's fracture energy. Simultaneously, the Mg-O bonds are more ionic than the Si-O bonds, making them less sensitive to hydrolysis and alcohol attacks. Regarding surface regulation, the Lewis basic sites of MgO preferentially adsorb water molecules, reducing direct hydrothermal corrosion of the Si-O-Si bonds; Mg... 2+ Introducing MgO into the SiO2 network generates lattice distortion and oxygen vacancies, suppressing pore coarsening caused by Ostwald ripening. In a synergistic effect, MgO and existing ZrO2 additives form a Zr-O-Mg-O-Si mixed crosslinked network, where Zr... 4+ High coordination characteristics and Mg 2+ The charge compensation effect of Cu enhances the rigidity of the carrier, effectively reducing the silicon loss rate while maintaining Cu 0 High dispersion extends the catalyst's operating cycle.

[0017] To achieve the above objectives, the present invention adopts the following technical solution: A catalyst for the hydrogenation of methyl 3-hydroxypropionate to 1,3-propanediol comprises an active component of copper, auxiliary agents of zinc oxide, zirconium oxide, and magnesium oxide, and a structural support of silica. Further, the weight percentages of the catalyst components are as follows: active component copper oxide 30-50 wt%, zinc oxide 0.1-5 wt%, zirconium oxide 0.1-10 wt%, magnesium oxide 0.1-5 wt%, and silica 40-70 wt%.

[0018] The preparation method of this catalyst includes the following steps: 1) Add copper metal salt to an appropriate amount of deionized water, stir, and let it dissolve at room temperature; then add zinc and magnesium metal salts to the copper metal salt solution. 2) Add tetraethyl orthosilicate and zirconium propoxide to an appropriate amount of anhydrous ethanol, stir well, and let it dissolve at room temperature; 3) Add the solution from step 2) to the solution from step 1), stir continuously and heat to form a metal mixture; 4) Prepare an ammonium carbonate aqueous solution of a specific concentration. Add the ammonium carbonate aqueous solution and the metal mixture prepared in step 3) dropwise into the ethanol solution. Adjust the pH value to 7.5-9 and then stir continuously at room temperature to age the mixture. Then heat the mixture to 75-95℃. After the pH of the mixture drops below 6.5 and the upper layer of the mixture becomes clear after standing, cool it to room temperature. Wash the mixed slurry multiple times with deionized water, filter to form a filter cake, and dry in an oven at 60-120℃ for 2-24 hours. 5) Calcine the solid obtained in step 4) in air at 400-800℃ for 1-10 hours; 6) The calcined sample from step 5) is crushed, ground, and sieved to obtain a catalyst for the hydrogenation of methyl 3-hydroxypropionate to prepare 1,3-propanediol.

[0019] Further, the copper metal salt mentioned in step 1) is one or more of copper nitrate, copper acetate, copper acetylacetonate, and copper chloride.

[0020] Further, the zinc metal salt mentioned in step 1) is one or more of zinc nitrate hexahydrate, zinc acetate, and zinc chloride.

[0021] Further, the magnesium metal salt mentioned in step 1) is one or more of magnesium nitrate hexahydrate, magnesium acetate tetrahydrate, and magnesium chloride.

[0022] Furthermore, in step 1), the amount of deionized water used is 5-50 times the mass of the copper metal salt used.

[0023] Furthermore, the structural carrier precursor mentioned in step 2) is tetraethyl orthosilicate.

[0024] Furthermore, the mass ratio of anhydrous ethanol to the structural carrier precursor used in step 2) is 2-10:1.

[0025] Furthermore, the heating temperature described in step 3) is 30-100℃.

[0026] Further, the molar concentration of the ammonium carbonate aqueous solution in step 4) is 0.1-1 mol / L, and its dosage is calculated based on the molar amount of ammonium carbonate being 0.5-5 times the total molar amount of the active component and composite additives.

[0027] Furthermore, the mass ratio of the ethanol solution and the ammonium carbonate aqueous solution used in step 4) is 1:2-10.

[0028] Further, in step 4), the mass ratio of ethanol to water in the ethanol solution is 1:1-5.

[0029] Furthermore, the aging time described in step 4) is 2-24 hours.

[0030] Furthermore, the drying temperature in step 5) is 60-120℃, and the time is 2-24h.

[0031] Furthermore, the roasting described in step 5) is carried out at 400-800°C in an air atmosphere for 1-10 hours.

[0032] The catalyst is suitable for the hydrogenation of methyl 3-hydroxypropionate to prepare 1,3-propanediol.

[0033] Furthermore, the reaction takes place in a fixed-bed reactor.

[0034] Furthermore, the catalyst needs to be reduced before the reaction.

[0035] Furthermore, the reduction is carried out in a 5% (v / v) hydrogen / nitrogen mixture at a reduction temperature of 250-400°C for 2-20 hours.

[0036] Furthermore, the hydrogenation reaction is carried out in a pure hydrogen environment at a temperature of 100-200℃ and a pressure of 2-10 MPa.

[0037] Furthermore, the feedstock used in the hydrogenation reaction is a methanol mixture containing 2-25 wt% methyl 3-hydroxypropionate.

[0038] Furthermore, the space velocity of methyl 3-hydroxypropionate in the hydrogenation reaction is 0.01–1 h⁻¹. -1 The hydrogen-to-ester ratio is 50-1000.

[0039] Compared with the prior art, the significant feature of this invention is that it introduces a composite auxiliary component, which stabilizes the catalyst framework through chemical bonding, suppresses the problem of silicon loss from the catalyst, and exhibits good catalytic stability while ensuring high product activity. Attached Figure Description

[0040] Figure 1 Catalyst stability data tracking graph. Detailed Implementation

[0041] The present invention will be further illustrated by the following embodiments, but the following embodiments are not intended to limit the scope of the present invention.

[0042] Example 1: Preparation of 40CuO / 1ZnO / 0.5ZrO2 / 1MgO / SiO2 catalyst 1) Weigh 18.23g of copper nitrate trihydrate, 0.55g of zinc nitrate hexahydrate, and 0.96g of magnesium nitrate hexahydrate and dissolve them in 300g of deionized water. Stir continuously until transparent to obtain a copper metal mixed solution. Weigh 0.3g of zirconium propoxide and dissolve it in 150g of anhydrous ethanol. Disperse it ultrasonically for 10min and stir thoroughly for 1h. Then add 30.2g of tetraethyl orthosilicate. Add this mixture to the copper metal mixed solution, continue stirring and heat to 50℃. Stop heating after the mixed solution becomes transparent to obtain a mixed metal solution.

[0043] 2) Weigh 9g of ammonium carbonate into 300g of water, stir continuously, and then ultrasonically disperse for 10min to form an ammonium carbonate solution. Add 50g of ethanol and 50g of water to a beaker and stir to form an ethanol solution. Then, add the prepared mixed metal solution and ammonium carbonate solution dropwise to the continuously stirred ethanol solution, adjust the pH to 8.5, and continue stirring at room temperature for 12h. Then, raise the temperature to 90℃ to evaporate excess ammonium carbonate from the system. After the pH drops below 6.5, turn off the stirring and let the mixture stand. After the upper layer of liquid becomes clear, turn off the heating and cool to room temperature. Wash the obtained mixed slurry several times with deionized water and filter to form a filter cake. Then, dry it in an oven at 120℃ for 12h. Calcine the obtained solid in air at 700℃ for 5h. Then, crush, grind, and pass through a 40-60 mesh sieve to obtain catalyst particles, which contain 40wt% CuO, 1wt% ZnO, 0.5wt% ZrO2, and 1wt% MgO.

[0044] Example 2: Preparation of 40CuO / 1ZnO / 0.5ZrO2 / 0.5MgO / SiO2 catalyst 1) Weigh 18.23g of copper nitrate trihydrate, 0.55g of zinc nitrate hexahydrate, and 0.48g of magnesium nitrate hexahydrate and dissolve them in 300g of deionized water. Stir continuously until transparent to obtain a copper metal mixed solution. Weigh 0.3g of zirconium propoxide and dissolve it in 150g of anhydrous ethanol. Disperse it ultrasonically for 10min and stir thoroughly for 1h. Then add 30.2g of tetraethyl orthosilicate. Add this mixture to the copper metal mixed solution, continue stirring and heat to 50℃. Stop heating after the mixed solution becomes transparent to obtain a mixed metal solution.

[0045] 2) Weigh 9g of ammonium carbonate and dissolve it in 300g of water. After continuous stirring, ultrasonically disperse the solution for 10 minutes to form an ammonium carbonate solution. Add 50g of ethanol and 50g of water to a beaker and stir to form an ethanol solution. Then, add the prepared mixed metal solution and ammonium carbonate solution dropwise to the continuously stirred ethanol solution and adjust the pH to 8.5. Continue stirring at room temperature for 12 hours, then raise the temperature to 90℃ to evaporate excess ammonium carbonate. After the pH drops below 6.5, turn off the stirring and allow the mixture to stand. After the supernatant becomes clear, turn off the heating and cool to room temperature. The mixed slurry was washed multiple times with deionized water and filtered to form a filter cake. After drying in an oven at 120°C for 12 hours, the resulting solid was calcined in air at 700°C for 5 hours. The calcined sample was then crushed, ground, and passed through a 40-60 mesh sieve to obtain catalyst particles, which contained 40wt% CuO, 1wt% ZnO, 0.5wt% ZrO2, and 0.5wt% MgO.

[0046] Example 3: Preparation of 40CuO / 1ZnO / 0.5ZrO2 / 3MgO / SiO2 catalyst 1) Weigh 18.23g of copper nitrate trihydrate, 0.55g of zinc nitrate hexahydrate, and 2.85g of magnesium nitrate hexahydrate and dissolve them in 300g of deionized water. Stir continuously until transparent to obtain a copper metal mixed solution. Weigh 0.3g of zirconium propoxide and dissolve it in 150g of anhydrous ethanol. Disperse it ultrasonically for 10min and stir thoroughly for 1h. Then add 30.2g of tetraethyl orthosilicate. Add this mixture to the copper metal mixed solution, continue stirring and heat to 50℃. Stop heating when the mixed solution becomes transparent to obtain a mixed metal solution.

[0047] 2) Weigh 9g of ammonium carbonate and dissolve it in 300g of water. After continuous stirring, ultrasonically disperse for 10 minutes to form an ammonium carbonate solution. Add 50g of ethanol and 50g of water to a beaker and stir to form an ethanol solution. Then, add the prepared mixed metal solution and ammonium carbonate solution dropwise to the continuously stirred ethanol solution and adjust the pH to 8.5. Continue stirring at room temperature for 12 hours, then raise the temperature to 90℃ to evaporate excess ammonium carbonate from the system. After the pH drops below 6.5, turn off the stirring and let the mixture stand. After the upper layer of liquid becomes clear, turn off the heating and cool to room temperature. Wash the obtained mixed slurry several times with deionized water and filter to form a filter cake. Then, dry it in an oven at 120℃ for 12 hours. Calcine the obtained solid in air at 700℃ for 5 hours. Then, crush and grind the calcined sample and pass it through a 40-60 mesh sieve to obtain catalyst particles, which contain 40wt% CuO, 1wt% ZnO, 0.5wt% ZrO2, and 3wt% MgO.

[0048] Comparative Example 1: Preparation of 40CuO / SiO2 catalyst 1) Weigh 18.23g of copper nitrate trihydrate and dissolve it in 300g of deionized water, stirring continuously until a transparent solution is obtained; weigh 30.2g of tetraethyl orthosilicate and dissolve it in 150g of anhydrous ethanol, then add the ethanol solution of tetraethyl orthosilicate to the copper aqueous solution, continue stirring and heat to 50℃, and stop heating after the mixed solution becomes transparent to obtain a mixed metal solution.

[0049] 2) Weigh 9g of ammonium carbonate and dissolve it in 300g of water. After continuous stirring, ultrasonically disperse the solution for 10 minutes to form an ammonium carbonate solution. Add 50g of ethanol and 50g of water to a beaker and stir to form an ethanol solution. Then, add the prepared mixed metal solution and ammonium carbonate solution dropwise to the continuously stirred ethanol solution and adjust the pH to 8.5. Continue stirring at room temperature for 12 hours, then raise the temperature to 90℃ to evaporate excess ammonium carbonate. After the pH drops below 6.5, stop stirring and allow the mixture to stand. After the upper layer becomes clear, stop heating and cool to room temperature. Wash the resulting slurry several times with deionized water and filter to form a filter cake. Dry the cake in an oven at 120℃ for 12 hours. Then, calcine the obtained solid in air at 700℃ for 5 hours. Crush, grind, and pass the calcined sample through a 40-60 mesh sieve to obtain catalyst particles containing 40wt% CuO.

[0050] Preparation of Comparative Example 2: 40CuO / 1ZnO / 0.5ZrO2 / SiO2 catalyst 1) Weigh 18.23g of copper nitrate trihydrate and 0.55g of zinc nitrate hexahydrate and dissolve them in 300g of deionized water. Stir continuously until transparent to obtain a copper metal mixed solution. Weigh 0.3g of zirconium propoxide and dissolve it in 150g of anhydrous ethanol. Disperse it ultrasonically for 10min and stir thoroughly for 1h. Then add 30.2g of tetraethyl orthosilicate. Add this mixture to the copper metal mixed solution, continue stirring and heat to 50℃. Stop heating when the mixed solution becomes transparent to obtain a mixed metal solution.

[0051] 2) Weigh 9g of ammonium carbonate and dissolve it in 300g of water. After continuous stirring, ultrasonically disperse for 10 minutes to form an ammonium carbonate solution. Add 50g of ethanol and 50g of water to a beaker and stir to form an ethanol solution. Then, add the prepared mixed metal solution and ammonium carbonate solution dropwise to the continuously stirred ethanol solution and adjust the pH to 8.5. Continue stirring at room temperature for 12 hours, then raise the temperature to 90℃ to evaporate excess ammonium carbonate from the system. After the pH drops below 6.5, turn off the stirring and let the mixture stand. After the upper layer of liquid becomes clear, turn off the heating and cool to room temperature. Wash the obtained mixed slurry several times with deionized water and filter to form a filter cake. Then, dry it in an oven at 120℃ for 12 hours. Calcine the obtained solid in air at 700℃ for 5 hours. Then, crush and grind the calcined sample and pass it through a 40-60 mesh sieve to obtain catalyst particles, of which CuO 40wt%, ZnO 1wt%, and ZrO2 0.5wt%.

[0052] Catalyst evaluation: Using a methanol solution of methyl 3-hydroxypropionate as the reactant, the performance of the catalyst was evaluated in a high-pressure fixed-bed reactor. The catalyst's conversion and selectivity were assessed through a 1000-hour long-term operation to evaluate its stability. The catalyst loading was 6 g. Before feeding, the catalyst was reduced in a 5% (v / v) hydrogen / nitrogen mixture at 350℃, 8 MPa, a hydrogen flow rate of 100 mL / min, and a reduction time of 10 h. Reaction conditions: methyl 3-hydroxypropionate was diluted with methanol to a 5% (w / v) concentration; reaction temperature was 150℃; reaction pressure was 8 MPa; and the feed volume hourly space velocity (VHSV) was 0.2 h⁻¹. -1 The hydrogen-to-ester ratio was 500. After the reaction temperature and pressure stabilized, methyl 3-hydroxypropionate solution was introduced, allowing the sample to penetrate the catalyst bed. After the high-performance liquid level appeared in the thermal high-performance liquid condenser, the product was collected every 24 hours. GC-MC was used to perform quantitative and qualitative analysis on the raw materials and hydrogenated products, and the conversion rate of methyl 3-hydroxypropionate (3-HMP) hydrogenation and the selectivity of 1,3-propanediol (1,3-PDO) were calculated.

[0053] The pore structure characteristics of the catalysts prepared in the examples and comparative examples are shown in Table 1.

[0054] Table 1 Characterization of catalyst specific surface area and pore structure

[0055] The structural characterization data of the catalysts obtained in Examples 1-3 and Comparative Examples 1-2 in Table 1 show that the addition of an appropriate amount of additives did not lead to a significant decrease in the specific surface area and pore volume of the catalyst. This indicates that large zirconium oxide and zinc oxide particles were not formed to block the catalyst pores. It is possible that a layered copper silicate structure was formed, which increased the specific surface area of ​​the catalyst, which is beneficial to the dispersion of copper active species.

[0056] The catalysts prepared in the examples and comparative examples were characterized by XRD, and the particle size of the active species and the ratio of monovalent copper to copper were calculated. The results are shown in Table 2.

[0057] Table 2 Particle size analysis of Cu, the active component in the catalyst

[0058] The comparison of data in Table 2 shows that the addition of the additives reduced the particle size of CuO, Cu, and Cu2O in the catalyst, thus promoting the dispersion of the active components. Furthermore, the addition of the additives increased the Cu2O ratio, which positively impacted the catalyst activity. Meanwhile, unlike the catalysts prepared in Comparative Examples 1 and 2, where the Cu and Cu2O particle sizes significantly increased after the reaction, the catalysts prepared in Examples 1-3 did not show a significant increase in Cu and Cu2O particle sizes after the reaction. This indicates that the addition of zinc-zirconium-magnesium additives helps anchor the copper active material, enhances the interaction between copper and the support, and effectively inhibits sintering.

[0059] Table 3. Test of tetramethoxysilane content in products during catalyst operation.

[0060] The silicon content of the products in the examples and comparative examples was analyzed using inductively coupled plasma atomic emission spectrometry (ICP-AES). Table 3 shows that the silicon content in the products of Examples 1-3 was 86.4, 89.5, and 79.6 ppm, respectively, while the silicon content in the comparative examples was greater than 300 ppm. The silicon content in the products of the examples was significantly lower than that in the comparative examples. This demonstrates that the addition of magnesium oxide effectively suppressed the problem of silicon loss from the catalyst.

[0061] Catalyst stability analysis and evaluation The long-term stability of the catalysts prepared in the examples and comparative examples was tested through catalyst stability testing experiments. The test run time was 1000 h. During the test run, the 3-HMP conversion and 1,3-PDO selectivity were monitored at 24-hour intervals. Specific operating details can be found in [link to relevant documentation]. Figure 1 Due to the presence of magnesium oxide as an additive, the catalysts in Examples 1, 2, and 3 maintained a 3-HMP conversion rate of over 85% in the 700-1000 h range. In contrast, Comparative Example 1, a copper-silicon catalyst without additives, showed a rapid decline in conversion rate after 96 h. Comparative Example 2, a composite metal catalyst with zinc oxide and zirconium oxide as additives, maintained the same 3-HMP conversion rate as the examples until 600 h, after which the 3-HMP conversion rate gradually decreased. This demonstrates that the addition of magnesium oxide effectively improves catalyst stability.

[0062] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A catalyst for the hydrogenation of methyl 3-hydroxypropionate to 1,3-propanediol, characterized in that, It includes active components copper oxide, auxiliary agents zinc oxide, zirconium oxide and magnesium oxide, and structural carrier silicon dioxide; the weight percentage of each component is as follows: copper oxide 30-50 wt%, zinc oxide 0.1-5 wt%, zirconium oxide 0.1-10 wt%, magnesium oxide 0.1-5 wt%, and silicon dioxide 40-70 wt%, based on a total weight percentage of 100%.

2. A method for preparing the catalyst as described in claim 1, characterized in that, Includes the following steps: 1) Add copper metal salt to an appropriate amount of deionized water and stir until dissolved at room temperature; then add zinc and magnesium metal salts to the copper metal salt solution and stir until dissolved at room temperature. 2) Add tetraethyl orthosilicate and zirconium propoxide to an appropriate amount of anhydrous ethanol, stir well, and let it dissolve at room temperature; 3) Add the solution from step 2) to the solution from step 1), stir continuously and heat to form a metal mixture; 4) Prepare an ammonium carbonate aqueous solution of a specific concentration. Add the ammonium carbonate aqueous solution and the metal mixture prepared in step 3) dropwise into the ethanol solution. Adjust the pH value to 7.5-9, and then stir continuously at room temperature to age the mixture. Then heat the mixture to 75-95℃. After the pH of the mixture drops below 6.5 and the upper layer of the mixture becomes clear after standing, cool it to room temperature. Wash the mixture slurry several times with deionized water, filter it to form a filter cake, and dry it in an oven at 60-120℃ for 2-24 hours. 5) Calcine the solid obtained in step 4) in air at 400-800℃ for 1-10 hours; 6) The sample calcined in step 5) is crushed, ground, and sieved to obtain a catalyst for the hydrogenation of methyl 3-hydroxypropionate to 1,3-propanediol.

3. The preparation method according to claim 2, characterized in that, The copper metal salt is one or more of copper nitrate, copper acetate, copper acetylacetonate, and copper chloride; the zinc metal salt is one or more of zinc nitrate, zinc sulfate, zinc acetate, and zinc chloride; and the magnesium metal salt is one or more of magnesium nitrate hexahydrate, magnesium acetate tetrahydrate, and magnesium chloride.

4. The preparation method according to claim 2, characterized in that, In step 2), the mass ratio of tetraethyl orthosilicate to anhydrous ethanol is 1:2-10.

5. The preparation method according to claim 2, characterized in that, In step 4), the mass ratio of ethanol to water in the ethanol solution is 1:1-5.

6. The preparation method according to claim 2, characterized in that, The aging step in step 4) involves continuous stirring at room temperature for 2-24 hours.

7. The preparation method according to claim 2, characterized in that, The heating temperature mentioned in step 3) is 30-100℃.

8. The preparation method according to claim 2, characterized in that, The molar concentration of the ammonium carbonate aqueous solution mentioned in step 4) is 0.1-1 mol / L, and its dosage is calculated based on the molar amount of ammonium carbonate being 0.5-5 times the total molar amount of the active component and composite additives.

9. The preparation method according to claim 2, characterized in that, The mass ratio of ethanol solution and ammonium carbonate aqueous solution used in step 4) is 1:2-10.

10. The application of the catalyst according to claim 1 in the hydrogenation of methyl 3-hydroxypropionate to prepare 1,3-propanediol.

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