Reverse supported catalyst for ester hydrogenation reaction, its preparation method and application
By loading CuNi alloy particles onto SiO2 spheres and dispersing CeO2 sub-nano clusters in the catalyst configuration, the problem of easy deactivation of copper-based catalysts was solved, and efficient production of 1,3-propanediol was achieved, with significantly improved catalyst activity and stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-28
- Publication Date
- 2026-04-14
AI Technical Summary
Copper-based catalysts are prone to deactivation in ester hydrogenation reactions, leading to a decrease in conversion and a reduction in the yield of the main product, 1,3-propanediol.
Using SiO2 spheres as a support, CuNi alloy particles are loaded, and unsaturated CeO2 sub-nano clusters are dispersed at high density on the surface of the CuNi alloy particles to form a catalytic configuration of CuNi alloy particles with reverse CeO2 loading. The CeO2 sub-nano clusters provide surface defect sites, regulate the electronic environment of CuNi active centers, and enhance the activation and dissociation ability of H2 and the adsorption and activation of C=O bonds in 3-HPM molecules.
The efficient selective hydrogenation of 3-HPM to 1,3-PDO was achieved with a significant reduction in copper content but an increase in catalytic activity. The yield of 1,3-PDO was close to 97.0%, and the catalyst maintained high activity and stability during recycling.
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Figure CN120571585B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst preparation technology, specifically relating to a reverse-supported catalyst for ester hydrogenation reaction, its preparation method, and its application. Background Technology
[0002] 1,3-Propanediol, or 1,3-PDO, is an important petrochemical raw material widely used in pharmaceuticals, inks, and cosmetics. Its most important application is as a polymerization monomer, condensing with terephthalic acid to form flexible polybutylene terephthalate (PET) and rigid polyethylene terephthalate (PET), which have broad market prospects.
[0003] Currently, the industrial production of 1,3-propanediol still faces key challenges such as low product efficiency and numerous byproducts. The main methods for preparing 1,3-propanediol include acrolein hydration, bioengineering, ethylene oxide formylation, and ethylene oxide hydrogen esterification.
[0004] In comparison, the ethylene oxide hydrogen esterification method is more environmentally friendly, uses cheaper and more readily available raw materials, and produces a more efficient 1,3-propanediol product, making it a popular method for producing 1,3-propanediol. Furthermore, the intermediate methyl 3-hydroxypropanoate (Methyl 3-hydroxypropanoate, abbreviated as 3-HPM) produced in this method is stable. Because 3-HPM contains a β-hydroxyl group, it is more easily dehydrogenated, creating more suitable ester hydrogenation sites and significantly improving the selectivity of the main product, 1,3-propanediol.
[0005] The hydrogen esterification of ethylene oxide involves two steps: carbonylation and ester hydrogenation. However, the hydrogenation of the intermediate 3-HPM during the ester hydrogenation process still faces challenges such as numerous byproducts and low conversion rates. Copper-based catalysts have become the mainstream choice for ester hydrogenation due to their excellent selective hydrogenation ability and economic efficiency. However, at higher reaction temperatures, copper-based catalysts often experience Cu active center sintering, leading to catalyst deactivation and a decrease in the conversion rate of the ester hydrogenation reaction, thereby reducing the yield of the main product, 1,3-propanediol. Summary of the Invention
[0006] To address the technical problem that the copper-based catalysts mentioned above are prone to deactivation at high temperatures, leading to a decrease in the conversion rate of ester hydrogenation reactions and thus reducing the yield of the main product 1,3-propanediol, this invention provides a reverse-supported catalyst for ester hydrogenation reactions, its preparation method, and its application.
[0007] This invention uses SiO2 spheres as a support, with CuNi alloy particles loaded onto the support surface as active centers. High-density coordinatingly unsaturated CeO2 sub-nano clusters are dispersed on the surface of the CuNi alloy particles, forming a catalytic configuration of CuNi alloy particles with reverse-supported CeO2. The CeO2 sub-nano clusters provide surface defect sites, modulating the electronic environment of the CuNi active centers and enhancing the activation and dissociation ability of H2. Simultaneously, the CeO2 sub-nano clusters increase surface defect oxygen vacancies, which can adsorb H2 molecules and promote their dissociation into active H*, strengthening the adsorption of C=O bonds in 3-HPM molecules and lowering the hydrogenation energy barrier. Through the oxygen vacancy effect of the CeO2 sub-nano clusters and the active centers of the CuNi alloy particles, the adsorption and activation of reactants are synergistically promoted, achieving highly efficient selective hydrogenation of 3-HPM to 1,3-PDO.
[0008] The first objective of this invention is to provide a reverse-supported catalyst for ester hydrogenation reactions, wherein the reverse-supported catalyst uses SiO2 spheres as a support, CuNi alloy particles are loaded on the surface of the support, and coordinatingly unsaturated CeO2 clusters are dispersed on the surface of the CuNi alloy particles.
[0009] Preferably, the size of the CuNi alloy particles is 3nm to 5nm; the size of the coordinated unsaturated CeO2 clusters is less than 1nm.
[0010] Preferably, the mass ratio of Cu, Ni and CeO2 in the reverse-supported catalyst is 15:5:3 to 7.
[0011] Preferably, SiO2 accounts for 73% to 77% of the mass percentage of the reverse-supported catalyst.
[0012] A second objective of this invention is to provide a method for preparing the above-mentioned reverse-supported catalyst, comprising the following steps:
[0013] Soluble copper salt, soluble nickel salt, and soluble cerium salt are mixed and then ammonia water is added to form a metal ammonia complex with the metal ions, resulting in a mixed metal salt solution.
[0014] Using SiO2 spheres as a carrier, the carrier is immersed in a mixed metal salt solution to etch the carrier. At the same time, the reaction is carried out at 90℃~100℃, and the metal amine complex decomposes. The resulting metal hydroxy oxide is loaded on the surface of the etched carrier, thus obtaining a composite precursor of SiO2 loaded with metal hydroxy oxide.
[0015] The composite precursor was calcined in air to form CuNiCe metal oxide on the support surface; then it was reduced in hydrogen atmosphere to reduce the copper-nickel oxide on the support surface to CuNi alloy particles, and the coordinated unsaturated CeO2 clusters were dispersed on the surface of the CuNi alloy particles to obtain a reverse supported catalyst.
[0016] Preferably, the pH value of the mixed metal salt solution is 10 to 11.
[0017] This invention adjusts the pH of the mixed metal salt solution to 10-11 by adding excess ammonia. Under alkaline conditions, soluble copper, nickel, and cerium salts form stable metal ammonia complexes, such as [Cu(NH3)4]. 2+ [Ni(NH3)4] 2+ and [Ce(NH3)4] 3+ This avoids direct precipitation of metal ions from the metal salts, ensuring the homogeneity of the mixed metal salt solution. Simultaneously, the formed soluble metal ammonia complex achieves uniform loading through the slow release of metal ions.
[0018] It should be noted that the present invention uses SiO2 spheres as a carrier, immerses the carrier in a mixed metal salt solution, and slowly releases NH3 in the solution through heat treatment to lower the pH, causing the metal ammonia complex to decompose and form metal hydroxy oxides; at the same time, the SiO2 spheres are gradually etched in the alkaline solution to form surface nanopores, promoting the gradual loading of metal species on the surface of the SiO2 carrier.
[0019] Preferably, Cu in soluble copper salts 2+ Ni in soluble nickel salts 2 + and Ce in soluble cerium salts 2+ The molar ratio is 11.8:4.3:1 to 2.5. At this dosage, a high degree of metal dispersion can be ensured while forming a large number of low-coordination unsaturated CeO2 clusters and defective oxygen vacancies, which promotes the adsorption and activation of C=O groups of ester groups in the hydrogenation reactant 3-HPM, thus promoting the reaction.
[0020] This invention controls the copper content in the reverse-supported catalyst to be 15%, which is significantly lower than the copper content in copper-based catalysts in the prior art, which is 40% to 95%. By reducing the copper content, higher atom utilization rate of catalytic activity is achieved.
[0021] Preferably, the reaction time at 90℃~100℃ is 4h~6h.
[0022] Preferably, the specific method for preparing SiO2 spheres is as follows:
[0023] Quaternary ammonium salt and organosilicon source were dissolved in a solvent, and ammonia was added dropwise under stirring to control the pH to be neutral, thereby slowing down the condensation rate and forming uniform spherical particles. The particles were then calcined and activated at 550°C for 3 hours to remove the quaternary ammonium salt template and obtain SiO2 spheres.
[0024] Preferably, the mass ratio of quaternary ammonium salt, organosilicon source, and ammonia is 0.3-0.5:1-1.5:10-15; preferably, the quaternary ammonium salt is hexadecyltrimethylammonium bromide; and the organosilicon source is tetraethyl orthosilicate.
[0025] The composite precursor was calcined in air, causing the metal hydroxyl oxide to decompose and form a disordered CuNiCe mixed oxide; simultaneously, Ce... 3+ / Ce 4+ The species are uniformly mixed with Cu and Ni active species and dispersed on the surface of SiO2 support to obtain a multi-metal oxide composite precursor. Preferably, the calcination temperature is 250℃~450℃ and the time is 1.5h~3h.
[0026] The multi-metal oxide composite precursor was reduced in a hydrogen atmosphere. Due to the extremely weak interaction between the reducing metal oxide and the inert SiO2 support, the metal oxides agglomerated and synergistically reduced. Simultaneously, due to Ce... 3+ Ni 2+ and Cu 2 + The standard reduction potentials for Ce are -2.336 eV, -0.257 eV, and 0.3419 eV, respectively. 3+ Ni 2+ and Cu 2+ The standard reduction potentials of oxide species vary greatly, Ce 3+ Oxide species are difficult to reduce; however, copper-nickel oxide species can be simultaneously reduced to alloy nanoparticles. Under reducing conditions, CuNi is synergistically reduced to CuNi alloy nanoparticles, while CeO2 is redispersed to form coordinated unsaturated oxide clusters, forming a CuNi alloy particle-supported CeO2 sub-nano cluster structure, thus obtaining a reverse-supported catalyst.
[0027] This invention achieves a CuNi alloy particle loading on the SiO2 surface through dynamic control, and disperses coordinating unsaturated CeO2 sub-nano clusters on the surface of the CuNi alloy particles, forming a CuNi alloy particle reverse-loaded CeO2 sub-nano cluster catalytic structure.
[0028] Preferably, the reduction temperature is 150℃~350℃ and the time is 3h.
[0029] Preferably, the soluble copper salt is copper nitrate; the soluble nickel salt is nickel nitrate; and the soluble cerium salt is cerium nitrate.
[0030] A third objective of this invention is to provide the application of the above-mentioned reverse-supported catalyst in the catalytic hydrogenation of esters, wherein the reverse-supported catalyst catalyzes the selective hydrogenation of 3-HPM to prepare 1,3-PDO.
[0031] The preferred and specific application methods are as follows:
[0032] A reverse-supported catalyst, 3-HPM, and solvent were mixed and subjected to a catalytic reaction under heating and pressure to obtain 1,3-PDO; wherein the ratio of the reverse-supported catalyst, 3-HPM, and solvent was 1 g: 10 mL: 50 mL.
[0033] Preferably, the conditions for the catalytic reaction are: temperature of 120℃~160℃, pressure of 5MPa~8MPa, and time of 4h~5h.
[0034] Preferably, the solvent is methanol.
[0035] Compared with the prior art, the present invention has the following technical effects:
[0036] This invention uses SiO2 spheres as a support, on which CuNi alloy particles are loaded. High-density, coordinatingly unsaturated CeO2 sub-nano clusters are dispersed on the surface of the CuNi alloy particles, forming a catalytic configuration where CeO2 sub-nano clusters are reverse-loaded onto the CuNi alloy particle surface. Through the oxygen vacancy effect of the CeO2 sub-nano clusters and the active centers of the CuNi alloy particles, the adsorption and activation of reactants are synergistically promoted, achieving highly efficient selective hydrogenation of 3-HPM to 1,3-PDO.
[0037] The reverse-supported catalyst of this invention has a copper content of 15%, which is significantly lower than the copper content of 40% to 95% in the copper-based catalysts of the prior art, thus achieving higher atom utilization rate and catalytic activity. Moreover, under the action of the reverse-supported catalyst, the yield of 1,3-PDO of 3-HPM is close to 97.0% at 150°C and 8.0 MPa. Attached Figure Description
[0038] Figure 1 This is a flowchart illustrating the preparation process for a reverse-supported catalyst.
[0039] Figure 2 The catalytic activity of the catalysts prepared in Examples 1 to 3 and Comparative Examples 1 to 3 is described.
[0040] Figure 3 Cyclic stability of the reverse-supported catalyst in Example 1.
[0041] Figure 4 The catalytic activity of the reverse-supported catalyst in Example 1 changes with temperature.
[0042] Figure 5 The catalytic activity of the reverse-supported catalyst in Example 1 changes with pressure.
[0043] Figure 6The catalytic activity of the reverse-supported catalyst in Example 1 changes with reaction time.
[0044] Figure 7 The images are AC-TEM images of the reverse-supported catalyst of Example 1 at different magnifications; where a is a TEM image at the 200 nm scale and b is a spherical aberration corrected STEM image at the 5 nm scale.
[0045] Figure 8 The images are transmission electron microscope (TEM) images of the CuNi alloy catalyst in Comparative Example 1 at different magnifications; where a is a TEM image at the 200 nm scale and b is a spherical aberration corrected STEM image at the 5 nm scale. Detailed Implementation
[0046] To enable those skilled in the art to better understand and implement the technical solutions of this invention, the invention will be further described below with reference to specific embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0047] Unless otherwise specified, all reagents used in this invention are commercially available, and all methods used are conventional techniques in the art.
[0048] The following specific examples will provide further explanation.
[0049] Example 1
[0050] This embodiment provides a reverse-supported catalyst for ester hydrogenation reactions.
[0051] In this embodiment, the mass ratio of Cu, Ni, CeO2 and SiO2 in the reverse-supported catalyst is 15:5:5:75.
[0052] The specific preparation method is as follows:
[0053] Hexadecyltrimethylammonium bromide and tetraethyl orthosilicate were dissolved in ethanol, and ammonia was added dropwise under stirring; wherein the mass ratio of hexadecyltrimethylammonium bromide, tetraethyl orthosilicate and ammonia was 0.3:1:10, a mixed solution was obtained.
[0054] The mixed solution was allowed to stand for 24 hours, washed and dried, and then calcined at 550°C for 3 hours to obtain light yellow silicon dioxide sphere powder, i.e., SiO2.
[0055] 11.8 mmol of copper nitrate, 4.3 mmol of nickel nitrate and 1.46 mmol of cerium nitrate were mixed and ammonia was added dropwise to control the pH at 10.0, resulting in a mixed metal salt solution.
[0056] 3.78 g of silica spheres were immersed in a mixed metal salt solution for 4 h and reacted at 90 °C until the pH of the mixed metal salt solution dropped to 7.0. After washing and drying, the composite precursor was obtained.
[0057] The composite precursor was calcined in air at 400°C for 3 hours and then reduced in hydrogen at 300°C for 3 hours to obtain a reverse-supported catalyst, denoted as Cu-Ni-5CeO2.
[0058] Example 2
[0059] This embodiment provides a reverse-supported catalyst for ester hydrogenation reactions.
[0060] In this embodiment, the mass ratio of Cu, Ni, CeO2 and SiO2 in the reverse-supported catalyst is 15:5:3:77.
[0061] Following the preparation method of Example 1, a reverse-supported catalyst was obtained, denoted as Cu-Ni-3CeO2.
[0062] Example 3
[0063] This embodiment provides a reverse-supported catalyst for ester hydrogenation reactions.
[0064] In this embodiment, the mass ratio of Cu, Ni, CeO2 and SiO2 in the reverse-supported catalyst is 15:5:7:73.
[0065] Following the preparation method of Example 1, a reverse-supported catalyst was obtained, denoted as Cu-Ni-7CeO2.
[0066] Comparative Example 1
[0067] This comparative example provides a CuNi alloy catalyst.
[0068] In this comparative CuNi alloy catalyst, the mass ratio of Cu, Ni, and SiO2 is 15:5:80.
[0069] The specific preparation method is as follows:
[0070] Hexadecyltrimethylammonium bromide and tetraethyl orthosilicate were dissolved in ethanol, and ammonia was added dropwise under stirring; wherein the mass ratio of hexadecyltrimethylammonium bromide, tetraethyl orthosilicate and ammonia was 0.3:1:10, a mixed solution was obtained.
[0071] The mixed solution was allowed to stand for 24 hours, washed and dried, and then calcined at 550°C for 3 hours to obtain light yellow silicon dioxide sphere powder, i.e., SiO2.
[0072] 11.8 mmol of copper nitrate and 4.3 mmol of nickel nitrate were mixed, and ammonia was added dropwise to control the pH at 10.0, resulting in a mixed metal salt solution.
[0073] 3.78 g of silica spheres were immersed in a mixed metal salt solution for 4 h and reacted at 90 °C until the pH of the mixed metal salt solution dropped to 7.0. After washing and drying, the composite precursor was obtained.
[0074] The composite precursor was calcined in air at 400°C for 3 hours and then reduced in hydrogen at 300°C for 3 hours to obtain a CuNi alloy catalyst, denoted as CuNi.
[0075] Comparative Example 2
[0076] This comparative example provides CuCeO x Solid solution catalyst.
[0077] This comparative example of CuCeO x The mass ratio of Cu, Ce and SiO2 in the solid solution catalyst is 15:5:80.
[0078] The specific preparation method is as follows:
[0079] Hexadecyltrimethylammonium bromide and tetraethyl orthosilicate were dissolved in ethanol, and ammonia was added dropwise under stirring; wherein the mass ratio of hexadecyltrimethylammonium bromide, tetraethyl orthosilicate and ammonia was 0.3:1:10, a mixed solution was obtained.
[0080] The mixed solution was allowed to stand for 24 hours, washed and dried, and then calcined at 550°C for 3 hours to obtain light yellow silicon dioxide sphere powder, i.e., SiO2.
[0081] 11.8 mmol of copper nitrate and 1.46 mmol of cerium nitrate were mixed and ammonia was added dropwise to control the pH at 10.0, resulting in a mixed metal salt solution.
[0082] 3.02 g of silica spheres were immersed in a mixed metal salt solution for 4 h and reacted at 90 °C until the pH of the mixed metal salt solution dropped to 7.0. After washing and drying, the composite precursor was obtained.
[0083] The composite precursor was calcined in air at 400°C for 3 hours, and then reduced in hydrogen at 300°C for 3 hours to obtain CuCeO. x Solid solution catalyst, denoted as CuCeO x .
[0084] Comparative Example 3
[0085] This comparative example provides a two-component physically mixed catalyst.
[0086] The two-component physically mixed catalysts in this comparative example include CuNi from Comparative Example 1 and CuCeO from Comparative Example 2. x Among them, CuNi and CuCeO x The mass ratio is 1:1.
[0087] The specific preparation method is as follows:
[0088] CuNi from Comparative Example 1 and CuCeO from Comparative Example 2 x The two-component physically mixed catalyst, denoted as CuCeO, was obtained by ball milling at a speed of 200 r / min for a mixing time of 0.5 h. x +CuNi.
[0089] like Figure 1 As shown, quaternary ammonium salt and organosilicon source are dissolved in a solvent, and ammonia is added dropwise under stirring to form uniform spherical particles. After calcination and activation, spherical SiO2 is obtained. Using SiO2 as a support, the support is immersed in a mixed metal salt solution. The metal ammonia complex decomposes to form metal hydroxyl oxides. Simultaneously, the surface of SiO2 is etched to form nanopores, and the metal hydroxyl oxides are deposited on the surface of SiO2, obtaining a composite precursor. The composite precursor is calcined in an air atmosphere and then reduced in a hydrogen atmosphere. Through two-step heat treatment, a catalytic configuration of CeO2 clusters reverse-supported on the surface of CuNi alloy particles is formed, resulting in a reverse-supported catalyst for ester hydrogenation reaction.
[0090] This invention studies the catalytic activity of the catalysts prepared in Examples 1-3 and Comparative Examples 1-3. The specific application methods are as follows:
[0091] After mixing 3-HPM, the catalyst and methanol, the mixture was placed in a high-temperature and high-pressure reactor. The catalytic performance of different catalysts in the conversion of 3-HPM to 1,3-PDO was investigated under a nitrogen atmosphere at 150℃ and an initial pressure of 3MPa. The ratio of catalyst, 3-HPM and solvent was 1g:10mL:50mL.
[0092] like Figure 2 As shown, Cu-Ni-3CeO2, Cu-Ni-5CeO2, and Cu-Ni-7CeO2 can effectively and selectively hydrogenate 3-HPM to produce 1,3-PDO. With increasing CeO2 loading in the reverse-supported catalyst, the 3-HPM conversion of the reverse-supported catalyst initially increases and then decreases. This is because a suitable CeO2 loading, through electronic regulation, can effectively enhance the metallic Cu content in the CuNi alloy particles. +The content of CeO2 promotes the stability of CuNi particles, thereby increasing the conversion rate of the reactants. However, excessive CeO2 will over-cover the surface of CuNi alloy particles, significantly reducing the exposure of active centers and leading to a decrease in 3-HPM conversion rate.
[0093] The 3-HPM conversion of CuNi without CeO2 loading was significantly low, only 58%, while the yield of 1,3-PDO was 54%; CuCeO x The solid solution catalyst showed poor selectivity for 1,3-PDO, with a yield of only 60%. The two-component physically mixed catalysts prepared from Comparative Examples 1 and 2 also showed poor selectivity for 1,3-PDO, with a yield of only 60%. Furthermore, the CuNi catalyst and CuCeO catalyst... x The solid solution catalyst and the two-component physical mixed catalyst exhibit significantly increased byproducts of intermolecular and intramolecular dehydration, namely methyl acrylate (MA) and methyl methoxypropionate (MMP). The Cu-Ni-5CeO2 catalytic conversion of 3-HPM prepared according to this invention achieves a yield of 97.0% for the production of 1,3-PDO.
[0094] like Figure 3 As shown, the Cu-Ni-5CeO2 in Example 1 still exhibited high 3-HPM conversion and 1,3-PDO selectivity after 6 cycles, with a 1,3-PDO yield close to 92%, and the catalyst activity only slightly decreased. This indicates that the reverse-supported catalyst prepared in this invention has high catalytic activity and stability.
[0095] This invention further investigates the catalytic performance of the reverse-supported catalyst of Example 1 in the conversion of 3-HPM to 1,3-PDO under different reaction temperatures, pressures, and times. The specific application methods are as follows:
[0096] 3-HPM, the reverse-supported catalyst of Example 1, and methanol were mixed and placed in a high-temperature and high-pressure reactor. Under a nitrogen atmosphere with an initial pressure of 3 MPa, the catalytic performance of the reverse-supported catalyst in the conversion of 3-HPM to 1,3-PDO was investigated at different reaction temperatures, pressures, and times within the range of 120°C to 160°C.
[0097] like Figure 4As shown, at a reaction temperature of 120°C, the Cu-Ni-5CeO2 catalyst achieved a 69% conversion rate of 3-HPM and a 89% yield of selectively producing 1,3-PDO. With increasing reaction temperature, the conversion rate of 3-HPM catalyzed by the Cu-Ni-5CeO2 catalyst increased, and the selectivity and yield of 1,3-PDO reached their highest levels at 150°C, with a yield of 97%. Further increases in temperature led to intramolecular dehydration of the reactants, resulting in a significant decrease in the selectivity of 1,3-PDO and a significant increase in the byproduct methyl acrylate. Therefore, the preferred reaction temperature for 3-HPM catalysis by the reverse-supported catalyst is 120°C to 160°C, and more preferably, the reaction temperature is 150°C.
[0098] like Figure 5 As shown, when the reaction pressure is increased to 5 MPa, the conversion rate of 3-HPM catalyzed by the Cu-Ni-5CeO2 catalyst is 62%, the selectivity for 1,3-PDO is low, and a large amount of the dehydration product methyl acrylate is generated in the product. With increasing pressure, the conversion rate of 3-HPM catalyzed by the Cu-Ni-5CeO2 catalyst increases, and the selectivity and yield of 1,3-PDO also increase. When the pressure is increased to 8 MPa, the selectivity of 1,3-PDO approaches 100%, and the yield reaches 97%. Therefore, the preferred reaction pressure for the reverse-supported catalyst catalyzing 3-HPM in this invention is 5 MPa to 8 MPa, and more preferably, the reaction pressure for the reverse-supported catalyst catalyzing 3-HPM is 8 MPa.
[0099] like Figure 6 As shown, reaction time significantly affects the conversion rate of 3-HPM catalyzed by the Cu-Ni-5CeO2 catalyst. After 1 hour of reaction, the 3-HPM conversion rate is only 39%. With increasing reaction time, the 3-HPM conversion rate gradually increases; after 4 hours of reaction, the 3-HPM conversion rate approaches 97%, the 1,3-PDO selectivity reaches 100%, and the yield approaches 97%. Therefore, the preferred reaction time for the reverse-supported catalyst to catalyze 3-HPM in this invention is 4 to 5 hours.
[0100] 2. Surface morphology characterization.
[0101] from Figure 7 Nanopores on the surface of a spherical SiO2 substrate can be clearly observed in the image; from Figure 7 In image b, spherical nanoparticles with lattice stripes can be observed against a dark gray background. The lattice spacing of approximately d = 0.207 nm belongs to the (111) crystal plane of the Cu-Ni alloy particles. High-contrast bright spots are observed above the particles. Due to the significant difference in atomic numbers (Z) of Cu (Z = 29), Ni (Z = 28), and Ce (Z = 58), the elemental contrast in the STEM image is related to Z.2 The contrast is directly proportional to the atomic number; elements with larger atomic numbers have stronger contrast (brighter) and can be confirmed to be sub-nanometer clusters formed by CeO2. This indicates that, unlike traditional CuNi alloy particles supported by CeO2 crystals, the CeO2 clusters (<1nm) in this Example 1 are reverse-loaded on the surface of fine CuNi alloy (3-5nm) particles, forming a typical reverse-loaded catalytic structure.
[0102] from Figure 8 Spherical nanoparticles with lattice stripes can be observed on a dark gray background. The lattice spacing of d = 0.207 nm to 0.209 nm belongs to the (111) crystal plane of the Cu-Ni alloy particles. The particle surface is clean and clear, without any extra bright spots, indicating that only CuNi alloy particles exist in Comparative Example 1, and there is no reverse-supported catalyst structure composed of CeO2 clusters.
[0103] Obviously, the above embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
Claims
1. A reverse-supported catalyst for ester hydrogenation reactions, characterized in that, The reverse-supported catalyst uses SiO2 spheres as a support, with CuNi alloy particles loaded on the surface of the support, and CeO2 clusters with coordination unsaturation dispersed on the surface of the CuNi alloy particles. The size of the CuNi alloy particles is 3nm~5nm; The size of the coordinatingly unsaturated CeO2 clusters is less than 1 nm; the mass ratio of Cu, Ni and CeO2 in the reverse-supported catalyst is 15:5:3~7.
2. The reverse-supported catalyst for ester hydrogenation reaction according to claim 1, characterized in that, The mass percentage of SiO2 in the reverse supported catalyst is 73% to 77%.
3. A method for preparing a reverse-supported catalyst for ester hydrogenation reaction as described in claim 1 or 2, characterized in that, Includes the following steps: Soluble copper salt, soluble nickel salt, and soluble cerium salt are mixed and then ammonia water is added to form a metal ammonia complex with the metal ions, resulting in a mixed metal salt solution. Using SiO2 as a support, the support is immersed in a mixed metal salt solution and reacted at 90℃~100℃ to etch the support. At the same time, the metal amine complex decomposes, and the resulting metal hydroxy oxide is loaded on the surface of the etched support to obtain a composite precursor of metal hydroxy oxide loaded with SiO2. The composite precursor was calcined in air to form CuNiCe metal oxide on the support surface; then it was reduced in hydrogen atmosphere to reduce the copper-nickel oxide on the support surface to CuNi alloy particles, and the coordinated unsaturated CeO2 clusters were dispersed on the surface of the CuNi alloy particles to obtain a reverse supported catalyst.
4. The method for preparing the reverse-supported catalyst for ester hydrogenation reaction according to claim 3, characterized in that, Cu in soluble copper salts 2+ Ni in soluble nickel salts 2+ Ce in soluble cerium salts 2+ The molar ratio is 11.8:4.3:1~2.
5.
5. The method for preparing the reverse-supported catalyst for ester hydrogenation reaction according to claim 3, characterized in that, The pH value of the mixed metal salt solution is 10~11.
6. The method for preparing the reverse-supported catalyst for ester hydrogenation reaction according to claim 3, characterized in that, The reaction time at 90℃~100℃ is 4h~6h; The calcination temperature is 250℃~450℃, and the time is 1.5h~3h; The reduction temperature is 150℃~350℃, and the time is 3 hours.
7. The method for preparing the reverse-supported catalyst for ester hydrogenation reaction according to claim 3, characterized in that, The soluble copper salt is copper nitrate; the soluble nickel salt is nickel nitrate; and the soluble cerium salt is cerium nitrate.
8. The use of the reverse-supported catalyst of claim 1 or 2 for ester hydrogenation reaction in the catalytic hydrogenation reaction of methyl 3-hydroxypropionate.
9. The application of the reverse-supported catalyst for ester hydrogenation according to claim 8 in the catalytic hydrogenation of methyl 3-hydroxypropionate, characterized in that, The specific application methods are as follows: A reverse-supported catalyst, methyl 3-hydroxypropionate, and solvent were mixed and subjected to a catalytic reaction under heating and pressure to obtain 1,3-propanediol; wherein the ratio of the reverse-supported catalyst, methyl 3-hydroxypropionate, and solvent was 1 g: 10 mL: 50 mL.
10. The application of the reverse-supported catalyst for ester hydrogenation according to claim 9 in the catalytic hydrogenation of methyl 3-hydroxypropionate, characterized in that, The conditions for the catalytic reaction are: temperature 120℃~160℃, pressure 5MPa~8MPa, and time 4h~5h.