Catalyst for synthesizing BDO and preparation method thereof

Abstract

The invention provides a catalyst for synthesizing BDO and a preparation method of the catalyst. The catalyst comprises an active component, a structural aid and an acidic regulator, wherein the active component is a nanoscale Cu-Zn-Al ternary metal compound. The catalyst provided by the invention shows high conversion rate, high selectivity and long service life in BDO preparation, solves the problems of easy sintering, insufficient active sites and the like of the traditional catalyst, and has significant industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically to a catalyst for the synthesis of BDO and its preparation method. Background Technology

[0002] 1,4-Butanediol (BDO) is an important chemical raw material widely used in polyurethane, pharmaceuticals, and solvents. Its efficient preparation has always been a key research direction in catalysis. Traditional BDO production processes often employ the Reppe method or maleic anhydride hydrogenation method, but these suffer from harsh reaction conditions, high energy consumption, and easy catalyst deactivation. In recent years, copper-based catalysts have been extensively studied due to their excellent hydrogenation performance. However, conventional copper-based catalysts are prone to sintering and carbon deposition under high temperature and pressure, leading to agglomeration of active components and a decrease in specific surface area, severely limiting catalytic efficiency and lifespan. Furthermore, the acidity adjustment of existing catalysts often relies on a single support, making it difficult to precisely control its pore size distribution and acidic sites, affecting the adsorption and conversion efficiency of reaction intermediates. On the other hand, catalyst preparation methods often result in uneven component distribution and easy particle agglomeration. While microwave-assisted and supercritical fluid technologies have some applications, they are mostly limited to single-component synthesis and have failed to achieve multi-component synergistic optimization.

[0003] Therefore, developing a novel catalyst that combines high activity, high stability, and low cost has become the key to breaking through the bottleneck in BDO production.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The primary objective of this invention is to provide a catalyst for the synthesis of BDO, which achieves significant improvements in catalyst structure and performance by constructing a multi-component composite active component, a core-shell structure aid, and a fluoride-modified mesoporous silica support.

[0006] The second objective of this invention is to provide a method for preparing the above-mentioned catalyst for synthesizing BDO. This method employs microwave-assisted co-precipitation combined with supercritical CO2 fluid mixing and ultrasonic-assisted impregnation technology, which significantly improves the dispersibility and specific surface area of ​​the catalyst.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: A catalyst for the synthesis of BDO, the catalyst comprising an active component, a structural aid, and an acid modifier; wherein the active component is a nanoscale Cu-Zn-Al ternary metal composite, the nanoscale Cu-Zn-Al ternary metal composite having a particle size of 10-50 nm; The structural additive is a rare earth metal oxide, wherein the mass ratio of the rare earth metal oxide to the active component is 1:5:1:20. The acid modifier is a fluoride-modified mesoporous SiO2 support with a pore size of 5-15 nm.

[0008] This invention provides a catalyst for the synthesis of BDO, used in the catalytic hydrogenation of BYD to BDO. The catalyst consists of three parts: an active component, a structural promoter, and an acid modifier. Significant improvements in catalytic performance are achieved through specific component selection and structural design. The active component is a nanoscale Cu-Zn-Al ternary metal composite with a particle size controlled within the range of 10-50 nm. Too small a particle size may lead to excessively high surface energy, exacerbating agglomeration, while too large a particle size reduces the exposure of active sites and lowers catalytic efficiency. This nanoscale active component optimizes electron transfer and intermediate adsorption in the hydrogenation reaction through the synergistic effect of Cu, Zn, and Al. Cu acts as the main active center, providing hydrogenation capacity; Zn stabilizes the valence state of Cu; and Al enhances the thermal stability of the catalyst by forming a spinel structure. The structural promoter is selected from... Rare earth metal oxides, with a mass ratio to the active component limited to 1:5-1:20, ensure that the additive effectively disperses the active component without reducing catalytic activity due to excessive coverage of active sites. Furthermore, the introduction of rare earth metal oxides not only modulates the electronic environment of the catalyst through their unique 4f electronic structure but also utilizes their oxygen vacancy characteristics to promote reactant activation and product desorption. The acidity regulator employs a fluoride-modified mesoporous SiO2 support with a pore size designed to be 5-15 nm. This pore size range effectively balances the diffusion rate of reactants with the accessibility of active sites, avoiding mass transfer limitations caused by excessively small pore sizes or loss of active components due to excessively large pore sizes. Fluoride modification further modulates the surface acidity and wettability of the support, enhancing the interaction between the active component and the support, thereby inhibiting the migration and sintering of the active component during the reaction.

[0009] In summary, the catalyst provided by this invention exhibits excellent catalytic performance in the hydrogenation of 1,4-butynediol (BYD) to 1,4-butanediol (BDO), demonstrating high activity, high selectivity, and excellent stability. This catalyst uses a nanoscale Cu-Zn-Al ternary metal complex as its core active component, optimizing electron transfer and intermediate adsorption in the hydrogenation reaction through the synergistic effect of Cu, Zn, and Al. Cu, as the main active center, provides highly efficient hydrogenation capacity; Zn stabilizes the valence state of Cu, preventing excessive reduction; and Al forms a spinel structure, enhancing the catalyst's thermal stability. Further doping with 0.1-0.5 wt% Pt atoms forms a Pt-Cu-Zn-Al quaternary complex, significantly improving the electronic and geometric effects of the catalytic center. The introduction of Pt not only modulates the d-band electronic structure of Cu and optimizes the adsorption strength of reaction intermediates but also promotes the directional hydrogenation reaction by forming more interfacial defect sites, thereby improving BDO selectivity and suppressing the formation of byproducts.

[0010] Furthermore, the catalyst structure of this invention exhibits multiple advantages in the BDO preparation process: First, the high dispersion of the nano-sized Cu-Zn-Al active component ensures abundant exposure of active sites, significantly improving the conversion efficiency of the reactants; second, the structural aid effect of rare earth metal oxides not only stabilizes the dispersion state of the active components but also promotes the conversion of reaction intermediates through their redox properties, reducing the generation of byproducts; finally, the fluoride-modified mesoporous SiO2 support optimizes the adsorption-desorption balance of the reactants by precisely controlling the acidic sites and pore size distribution, extending the catalyst's lifespan; in addition, this invention also solves the problems of easy sintering and carbon deposition of traditional catalysts under high temperature and high pressure environments through the synergistic effect of each component, providing reliable technical support for the efficient and green production of BDO.

[0011] Preferably, as a further feasible option, the molar ratio of Cu:Zn:Al in the nanoscale Cu-Zn-Al ternary metal composite is (40-60):(20-30):(10-30).

[0012] This invention further specifies the catalyst, specifically defining the molar ratio of Cu, Zn, and Al in the nanoscale Cu-Zn-Al ternary metal composite as (40-60):(20-30):(10-30). This is because Cu, as the core active component of the catalyst, is mainly responsible for catalyzing the hydrogenation reaction, and its content directly affects the activity and selectivity of the catalyst. If the Cu content is too low, there will be insufficient active sites, leading to a decrease in the reaction rate; while if the Cu content is too high, it is easy to cause the aggregation and sintering of Cu particles, and at the same time, it may generate byproducts due to excessive hydrogenation, reducing the selectivity of the target product BDO. The addition of Zn not only regulates the electronic state of Cu and inhibits excessive reduction of Cu, but also forms a stable ZnAl2O4 spinel structure through interaction with Al, enhancing the thermal stability and anti-sintering ability of the catalyst. The Zn content is controlled within a reasonable range to ensure its effective modification of Cu without occupying too many active sites due to excess. As a structural stabilizer, Al, when its content is within a suitable range, can ensure the mechanical strength and thermal stability of the catalyst support. At the same time, by forming composite oxides such as CuAl2O4 or ZnAl2O4, it further fixes the active components and prevents them from migrating or being lost during the reaction.

[0013] Preferably, as a further feasible option, the nanoscale Cu-Zn-Al ternary metal composite is further doped with 0.1-0.5 wt% Pt atoms to form a nanoscale Pt-Cu-Zn-Al quaternary metal composite.

[0014] This invention further specifies that 0.1-0.5 wt% Pt atoms are doped into the nanoscale Cu-Zn-Al ternary metal composite, thereby forming a nanoscale Pt-Cu-Zn-Al quaternary metal composite. Through precise control of the electronic structure and geometric environment of the active center, a breakthrough improvement in catalytic performance is achieved. Pt, as a noble metal, has significantly different atomic radius, electronegativity, and d-electron structure compared to Cu. When trace amounts of Pt (0.1-0.5 wt%) are doped into the Cu-Zn-Al lattice in atomic form, it triggers significant catalytic activity. The addition of Pt exhibits significant electronic and synergistic effects. From an electronic perspective, the addition of Pt alters the electron cloud distribution of Cu, causing a shift in the d-band center of Cu through charge transfer. This optimizes the adsorption strength of reaction intermediates at active sites, preventing catalyst poisoning due to excessive adsorption or low reaction efficiency due to insufficient adsorption. From a geometric perspective, the dispersion of Pt atoms in the Cu-Zn-Al lattice creates more interface sites and defect structures. These sites often possess higher catalytic activity, promoting hydrogenation while suppressing side reactions.

[0015] Meanwhile, when the Pt doping content is below 0.1 wt%, its modification effect is difficult to effectively cover the Cu active sites and cannot significantly improve catalytic performance. When the Pt content exceeds 0.5 wt%, it will not only lose its economic viability due to the surge in the cost of precious metals, but may also cause Pt atoms to aggregate into nanoparticles, destroying the homogeneous structure of Cu-Zn-Al, and even triggering unnecessary side reactions. Within this optimization range, Pt doping can improve the selectivity of BDO and extend the catalyst lifetime without significantly changing the main structure of the catalyst.

[0016] Preferably, as a further feasible option, the rare earth metal oxide is a core-shell structured La2O3@CeO2 composite, wherein CeO2 is the shell layer and La2O3 is the core layer, the shell layer thickness is 2-5 nm, and the La2O3 particle size is 5-10 nm.

[0017] This invention further specifies that the structural aid is a core-shell La2O3@CeO2 composite, in which CeO2 acts as a shell layer encapsulating the La2O3 core layer. The shell layer thickness is controlled at 2-5 nm, and the La2O3 core layer particle size is 5-10 nm. By constructing multi-level interfaces and controllable oxygen vacancy transport channels, the catalyst's anti-sintering performance and redox capability are synergistically improved. The La2O3 core layer has excellent thermal stability and basicity, which can effectively neutralize the acidic byproducts generated during the reaction and prevent acid poisoning on the catalyst surface. The CeO2 shell layer, with its unique fluorite structure and variable redox pairs, provides abundant oxygen vacancies and active oxygen species for the reaction. An excessively thin shell layer cannot completely cover the La2O3 core layer, which may lead to excessive exposure of basic sites and cause side reactions. An excessively thick shell layer will hinder the contact between the reactants and the core layer, reducing the synergistic effect between the aid and the active component. By controlling the core particle size of La2O3 to 5-10 nm, sufficient specific surface area and interfacial contact are ensured, while avoiding mass transfer limitations caused by excessively large particles.

[0018] More importantly, this core-shell structure exhibits a unique dynamic stabilization mechanism in high-temperature reaction environments. Oxygen vacancies in the CeO2 shell can form continuous migration channels under reaction conditions, enabling rapid transport of active oxygen species at the core-shell interface. When carbon deposits are generated at Cu active sites due to hydrogenation, the active oxygen provided by the CeO2 shell can promptly remove the carbon deposits. When there are excess oxygen species in the reaction system, the La2O3 core can act as an oxygen buffer to store excess oxygen and prevent excessive oxidation of the active components. This "oxygen pump" effect ensures that the catalyst maintains a clean active surface throughout long-term operation. Even more ingeniously, the La-O-Ce heterobonded structure formed at the core-shell interface generates strong metal-support interactions. This interaction not only immobilizes the loaded Cu-Zn-Al active components, preventing their high-temperature migration and aggregation, but also regulates the electron density of the active centers through interfacial charge transfer, optimizing the adsorption energy of reaction intermediates.

[0019] Preferably, as a further feasible option, ZrO2 nanoclusters are embedded in the CeO2 shell, and the content of the ZrO2 nanoclusters is 5-10 wt%.

[0020] This invention further specifies that ZrO2 nanoclusters are embedded in the CeO2 shell, and their content is controlled at 5-10 wt%. This technical feature achieves synergistic optimization of oxygen vacancy concentration, acidity / basicity distribution, and thermodynamic stability by constructing a composite interface structure of multi-metal oxides. The introduction of ZrO2 nanoclusters is achieved through precise control of Zr content. 4+ With Ce 4+ The lattice strain effect caused by the difference in ionic radius regulates the formation and migration behavior of oxygen vacancies at the atomic scale. When the ZrO2 content is in the range of 5-10 wt%, this doping-induced lattice distortion reaches the optimal balance: below 5 wt%, the strain effect is insufficient and it is difficult to significantly increase the oxygen vacancy concentration; above 10 wt%, it may lead to the instability of CeO2 fluorite structure and even induce phase separation. More ingeniously, the heterogeneous interface formed by ZrO2 nanoclusters and CeO2 generates highly active "interfacial oxygen vacancies". These sites have a much higher activation capacity for small molecules such as H2O and CO2 than single oxides, which can effectively remove oxygen-containing byproducts generated during the reaction and keep the active surface clean.

[0021] Analysis of the dynamic catalytic process reveals a unique functional mechanism of the ZrO2-CeO2 composite shell in the BDO preparation reaction: First, in the hydrogenation step, the introduction of ZrO2 modulates the mobility of oxygen species on the CeO2 surface, enabling more uniform transfer of active hydrogen species to the Cu active centers; second, in the dehydration or dehydrogenation steps, the moderately acidic sites provided by ZrO2 and the basic sites of CeO2 form an acid-base synergy, promoting the directional transformation of reaction intermediates; finally, in the catalyst regeneration stage, the stable oxygen vacancy network of ZrO2 ensures the mild penetration of the oxidizing atmosphere, avoiding excessive oxidation of the active components. This dynamic adaptability allows the catalyst to maintain stable performance even when the feed composition fluctuates or the operating conditions change.

[0022] Preferably, as a further feasible option, the ZrO2 nanoclusters have a particle size of 1-3 nm.

[0023] This invention further limits the particle size range of ZrO2 nanoclusters embedded in the CeO2 shell to 1-3 nm, thereby achieving a breakthrough improvement in catalyst performance from quantitative to qualitative change through precise control of the quantum size effect and interfacial strain effect of nanoclusters. When the size of ZrO2 nanoclusters is controlled in the range of 1-3 nm, the proportion of surface atoms increases, and this high surface atom exposure rate leads to an exponential increase in the density of interfacial active sites. At the same time, nanoclusters in this size range are exactly in the critical region of quantum confinement effect. Their electronic band structure retains the basic characteristics of bulk materials and exhibits a unique surface state distribution. This special electronic structure can promote charge transfer between active components and the support. More importantly, the 1-3 nm size range forms a specific matching relationship with the CeO2 lattice parameters: when the nanoclusters are smaller than 1 nm, their structural stability decreases sharply, and atomic migration or aggregation is prone to occur under reaction conditions; when the size exceeds 3 nm, the lattice mismatch with the CeO2 matrix is ​​too large, which will generate destructive dislocations rather than beneficial elastic strain at the interface.

[0024] Preferably, as a further feasible option, the fluoride is a mixture of NH4F and HF.

[0025] This invention further defines the acidity regulator, specifying that the fluoride is a mixture of NH4F and HF. The essence of fluoride modification lies in the substitution of hydroxyl groups on the surface of the SiO2 support by highly electronegative fluorine atoms, thereby achieving precise control over the acidity properties and surface structure of the support. The mixed use of NH4F and HF solves the key technical challenges faced by single fluorinating agents in the modification process, such as controlling the intensity of the reaction, adjusting the fluorination depth, and maintaining the surface morphology. From a chemical thermodynamic perspective, NH4F, as a mild fluorinating agent, mainly introduces Si-F bonds on the SiO2 surface through solid-phase reaction, and its high activation energy makes the fluorination process well controllable. HF, as a strong fluorinating agent, rapidly etches SiO2 to form SiF6 through a liquid-phase corrosion mechanism. 2- Soluble species with low reaction activation energies, when mixed in a specific ratio, NH4F's buffering effect can inhibit excessive corrosion by HF, while HF's activity can compensate for the insufficient reaction kinetics of NH4F. The two work together to form a gradient fluorination effect: the surface layer is dominated by rapid fluorination with HF, forming a high-density acidic site; the subsurface layer is characterized by gradual fluorination with NH4F, constructing moderately strong acidic sites; the deep layer basically maintains the original structure of the support, ensuring mechanical strength. This gradient fluorination structure enables the support to simultaneously possess abundant acidic sites and excellent structural stability, solving the contradiction that traditional fluorination methods cannot balance acidity and stability.

[0026] Preferably, as a further feasible option, the molar ratio of NH4F to HF is 1:1 to 1:3.

[0027] This invention further specifies that the molar ratio of NH4F to HF is 1:1-1:3. When the molar ratio of NH4F to HF is within the range of 1:1-1:3, NH4HF2, a key intermediate, will spontaneously form in the reaction system. Its unique chemical properties are the core of achieving controlled fluorination: NH4HF2 exhibits a moderate dissociation equilibrium in aqueous solution, which can provide sufficient F - and HF2 - The active species achieve effective fluorination without causing excessive corrosion like pure HF; at the same time, its cation NH4+ + It can temporarily stabilize newly formed Si-F bonds on the SiO2 surface through hydrogen bonding, preventing premature hydrolysis in an aqueous environment. Exceeding this ratio will lead to a qualitative change in the reaction characteristics. When NH4F is in excess (ratio <1:1), free NH4F in the system will form a hydrogen bond network with the hydroxyl groups on the SiO2 surface, hindering the deep diffusion of fluoride ions, causing fluorination to remain only on the surface. When HF is in excess (ratio >1:3), a large amount of H2F3 will be generated. - Highly corrosive species can cause the collapse of the carrier's pore structure.

[0028] The present invention also provides a method for preparing the above-mentioned catalyst, comprising the following steps: preparing the active component by microwave-assisted co-precipitation and mixing it with a structural aid in supercritical CO2 fluid for 1-2 hours to obtain a mixture; The mixture was then combined with an acid regulator by ultrasonic-assisted impregnation for 1-3 hours to obtain the crude product. The crude product is roasted under an inert atmosphere to obtain the final product.

[0029] Preferably, as a further feasible option, the microwave-assisted coprecipitation method uses a mixed solution of ammonium oxalate and ammonium bicarbonate as the precipitant, with a molar ratio of 1:1 to 1:3 and a pH value of 8.5 to 9.5.

[0030] This invention further refines the microwave-assisted coprecipitation method, specifically defining the precipitant as a mixed solution of ammonium oxalate and ammonium bicarbonate, with their molar ratio controlled within the range of 1:1 to 1:3, and the pH value maintained within the range of 8.5 to 9.5. The binary precipitant system of ammonium oxalate and ammonium bicarbonate achieves synchronous and uniform precipitation of metal ions through the synergistic effect of the two precipitants. Oxalate ions, as a moderately strong chelating ligand, can form complexes with the three metal ions with varying stability. This differentiated coordination ability precisely compensates for the natural differences in the solubility products of the three metal hydroxides, allowing the three metal ions to almost simultaneously detach from the complex state and form coprecipitates during the precipitation process. The addition of ammonium bicarbonate constructs a dynamic pH buffer system, and the HCO3 produced by its decomposition... - and CO3 2- Not only does it provide an additional source of precipitant, but more importantly, it utilizes NH4 + The / NH3 buffer pair precisely stabilizes the solution pH within the critical range of 8.5-9.5, while when pH < 8.5, Al 3+ The precipitation was incomplete; when pH > 9.5, Cu... 2+ It will partially form soluble [Cu(NH3)4] 2+ Complex ions lead to a higher Cu content in the final product. When the molar ratio of precipitant is limited to 1:1-1:3, the chelating effect of oxalate and the precipitation effect of carbonate reach the optimal balance. When the proportion of ammonium oxalate is too high, the strong chelating effect will slow down the precipitation rate, resulting in excessively large particle growth. When the proportion of ammonium bicarbonate is too high, the rapid precipitation reaction will produce a large number of crystal nuclei. Although smaller particles can be obtained, the particle size distribution is too wide.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention provides a catalyst for the synthesis of BDO, which achieves a significant improvement in catalyst structure and performance by constructing a multi-component composite active component, a core-shell structure aid and a fluoride-modified mesoporous silica support.

[0032] (2) The present invention provides a method for preparing the above-mentioned catalyst for synthesizing BDO. The preparation method adopts microwave-assisted co-precipitation method combined with supercritical CO2 fluid mixing and ultrasonic-assisted impregnation technology, which significantly improves the dispersibility and specific surface area of ​​the catalyst. Detailed Implementation

[0033] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] To more clearly illustrate the technical solutions in this invention, specific embodiments are described below.

[0035] Example 1 The specific preparation process of a catalyst for the synthesis of BDO according to the present invention is as follows: 1.1 Preparation of active components Microwave-assisted coprecipitation method was used: Cu(NO3)2, Zn(NO3)2 and Al(NO3)3 were dissolved in deionized water in a molar ratio of 40:20:10 to prepare a mixed metal salt solution. The precipitant is a mixed solution of ammonium oxalate and ammonium bicarbonate (molar ratio 1:1), and the pH is adjusted to 8.5; In a microwave reactor, a mixed metal salt solution was mixed with a precipitant and reacted at 80°C for 30 minutes to obtain a nano-sized Cu-Zn-Al ternary metal composite precipitate with a particle size of 10 nm. The active component was obtained by centrifuging, washing and drying the nano-sized Cu-Zn-Al ternary metal composite precipitate for later use. 1.2 Preparation of structural additives Preparation of core-shell structured La2O3@CeO2 composites: 1.2.1 Synthesis of La2O3 core layer Dissolve La(NO3)3·6H2O in deionized water to prepare a 0.1 mol / L solution; Ammonia (25 wt%) was slowly added dropwise with stirring to adjust the pH to 10, resulting in the formation of La(OH)3 precipitate. The La(OH)3 precipitate was separated by centrifugation, washed with deionized water until neutral, and then washed three times with ethanol to remove impurities. La(OH)3 precipitate was dried at 80℃ for 12 hours and then calcined in air at 500℃ for 2 hours to obtain La2O3 nanoparticles with a particle size of 5nm. 1.2.2 CeO2 shell coating The above-mentioned La2O3 nanoparticles were dispersed in deionized water and ultrasonically treated for 30 minutes to ensure uniform dispersion, thus obtaining an aqueous solution of La2O3 nanoparticles. Prepare a Ce(NO3)3·6H2O solution (0.05 mol / L). Add the Ce(NO3)3·6H2O solution to the aqueous solution of La2O3 nanoparticles at a molar ratio of La2O3 to CeO2 of 1:2. Then, while stirring in a 60°C water bath, slowly add urea solution (1 mol / L) and adjust the pH to 9.0. After reacting for 2 hours, the precipitate was separated by centrifugation, washed, and dried. The core-shell structure La2O3@CeO2 (shell thickness 2nm) was formed by calcination in air at 500℃ for 2 hours. 1.2.3 Embedding of ZrO2 nanoclusters La2O3@CeO2 was dispersed in ethanol and ultrasonicated for 30 minutes to obtain a carrier suspension. Prepare a ZrOCl2 solution (0.05 mol / L); The ZrOCl2 solution was then slowly added dropwise to the carrier suspension and stirred at a constant temperature of 60°C. After adding ammonia water dropwise, continue stirring for 2 hours to allow Zr(OH)4 to be fully adsorbed in the CeO2 channels and on the surface; After stirring, centrifuge and wash three times with ethanol to remove free impurities; The Zr(OH)4 / La2O3@CeO2 precursor was obtained by vacuum drying at 80℃ for 12 hours. Finally, the Zr(OH)4 / La2O3@CeO2 precursor was placed in a tube furnace and calcined at 400℃ for 2 hours under a nitrogen atmosphere to convert Zr(OH)4 into ZrO2 nanoclusters with a particle size of 1nm. After cooling, a structural additive is obtained; 1.3 Preparation of acidity regulators Fluorination modification of mesoporous SiO2 support was carried out using a mixed solution of NH4F and HF (molar ratio 1:1); The pore size of mesoporous SiO2 is 5 nm; The mesoporous SiO2 support was impregnated in a fluorinated mixed solution and reacted at 60°C for 2 hours, then washed and dried. 1.4 Catalyst Composite The active component and the structural additive were mixed in supercritical CO2 fluid at a mass ratio of 1:5 for 1 hour to obtain a mixture. The mixture was then combined with an acid regulator by ultrasonic-assisted impregnation for 1 hour to obtain the crude product; Finally, the crude product was calcined at 400°C for 3 hours under a N2 atmosphere to obtain the final catalyst.

[0036] Example 2 The specific preparation process of a catalyst for the synthesis of BDO according to the present invention is as follows: 1.1 Preparation of active components Microwave-assisted coprecipitation method was used: Cu(NO3)2, Zn(NO3)2 and Al(NO3)3 were dissolved in deionized water in a molar ratio of 60:30:30 to prepare a mixed metal salt solution; Prepare an H2PtCl6 solution with a Pt content of 0.5 wt%; The precipitant is a mixed solution of ammonium oxalate and ammonium bicarbonate (molar ratio 1:3). The mixed metal salt solution and the precipitant were slowly mixed at a volume ratio of 1:1, and the pH was adjusted to 9.5 to obtain the mixed solution. The mixture was transferred to a microwave reactor and heated uniformly to obtain a precipitate. The precipitate was then aged in a 60°C water bath for 1 hour to stabilize the crystal structure. The mixture was then centrifuged and washed with deionized water until Cl-free. - Wash twice more with ethanol; After washing, the precursor was vacuum dried at 80°C for 12 hours to obtain the precursor. In a mixed atmosphere of H2 / N2 (5:95), the precursor was calcined at 350°C for 2 hours to obtain a nano-sized Pt-Cu-Zn-Al quaternary metal composite with a particle size of 50 nm. 1.2 Preparation of structural additives Preparation of core-shell structured La2O3@CeO2 composites: 1.2.1 Synthesis of La2O3 core layer Dissolve La(NO3)3·6H2O in deionized water to prepare a 0.1 mol / L solution; Ammonia (25 wt%) was slowly added dropwise with stirring to adjust the pH to 10, resulting in the formation of La(OH)3 precipitate. The La(OH)3 precipitate was separated by centrifugation, washed with deionized water until neutral, and then washed three times with ethanol to remove impurities. La(OH)3 precipitate was dried at 80℃ for 12 hours and then calcined in air at 500℃ for 2 hours to obtain La2O3 nanoparticles with a particle size of 10 nm. 1.2.2 CeO2 shell coating The above-mentioned La2O3 nanoparticles were dispersed in deionized water and ultrasonically treated for 30 minutes to ensure uniform dispersion, thus obtaining an aqueous solution of La2O3 nanoparticles. Prepare a Ce(NO3)3·6H2O solution (0.05 mol / L). Add the Ce(NO3)3·6H2O solution to the aqueous solution of La2O3 nanoparticles at a molar ratio of La2O3 to CeO2 of 1:2. Then, while stirring in a 60°C water bath, slowly add urea solution (1 mol / L) and adjust the pH to 9.0. After reacting for 4 hours, the precipitate was separated by centrifugation, washed, and dried. The core-shell structure La2O3@CeO2 (shell thickness 5nm) was formed by calcination in air at 500℃ for 2 hours. 1.2.3 Embedding of ZrO2 nanoclusters La2O3@CeO2 was dispersed in ethanol and ultrasonicated for 30 minutes to obtain a carrier suspension. Prepare a ZrOCl2 solution (0.1 mol / L). The ZrOCl2 solution was then slowly added dropwise to the carrier suspension and stirred at a constant temperature of 60°C. After adding ammonia water dropwise, continue stirring for 2 hours to allow Zr(OH)4 to be fully adsorbed in the CeO2 channels and on the surface; After stirring, centrifuge and wash three times with ethanol to remove free impurities; The Zr(OH)4 / La2O3@CeO2 precursor was obtained by vacuum drying at 80℃ for 12 hours. Finally, the Zr(OH)4 / La2O3@CeO2 precursor was placed in a tube furnace and calcined at 400℃ for 2 hours under a nitrogen atmosphere to convert Zr(OH)4 into ZrO2 nanoclusters with a particle size of 3nm. After cooling, a structural additive is obtained; 1.3 Preparation of acidity regulators Fluorination modification of mesoporous SiO2 support was carried out using a mixed solution of NH4F and HF (molar ratio 1:3); The pore size of mesoporous SiO2 is 15 nm; The mesoporous SiO2 support was impregnated in a fluorinated mixed solution and reacted at 60°C for 2 hours, then washed and dried. 1.4 Catalyst Composite The active component and the structural additive were mixed in supercritical CO2 fluid at a mass ratio of 1:20 for 2 hours to obtain a mixture. The mixture was then combined with an acid regulator by ultrasonic-assisted impregnation for 3 hours to obtain the crude product; Finally, the crude product was calcined at 400°C for 3 hours under a N2 atmosphere to obtain the final catalyst.

[0037] Example 3 The specific preparation process of a catalyst for the synthesis of BDO according to the present invention is as follows: 1.1 Preparation of active components Microwave-assisted coprecipitation method was used: Cu(NO3)2, Zn(NO3)2 and Al(NO3)3 were dissolved in deionized water in a molar ratio of 50:25:20 to prepare a mixed metal salt solution. Prepare an H2PtCl6 solution with a Pt content of 0.3 wt%; The precipitant is a mixed solution of ammonium oxalate and ammonium bicarbonate (molar ratio 1:2). The mixed metal salt solution and the precipitant were slowly mixed at a volume ratio of 1:1, and the pH was adjusted to 9 to obtain the mixed solution. The mixture was transferred to a microwave reactor and heated uniformly to obtain a precipitate. The precipitate was then aged in a 60°C water bath for 1 hour to stabilize the crystal structure. The mixture was then centrifuged and washed with deionized water until Cl-free. - Wash twice more with ethanol; After washing, the precursor was vacuum dried at 80°C for 12 hours to obtain the precursor. In a mixed atmosphere of H2 / N2 (5:95), the precursor was calcined at 350°C for 2 hours to obtain a nano-sized Pt-Cu-Zn-Al quaternary metal composite with a particle size of 30 nm. 1.2 Preparation of structural additives Preparation of core-shell structured La2O3@CeO2 composites: 1.2.1 Synthesis of La2O3 core layer Dissolve La(NO3)3·6H2O in deionized water to prepare a 0.1 mol / L solution; Ammonia (25 wt%) was slowly added dropwise with stirring to adjust the pH to 10, resulting in the formation of La(OH)3 precipitate. The La(OH)3 precipitate was separated by centrifugation, washed with deionized water until neutral, and then washed three times with ethanol to remove impurities. La(OH)3 precipitate was dried at 80℃ for 12 hours and then calcined in air at 500℃ for 2 hours to obtain La2O3 nanoparticles with a particle size of 7.5 nm. 1.2.2 CeO2 shell coating The above-mentioned La2O3 nanoparticles were dispersed in deionized water and ultrasonically treated for 30 minutes to ensure uniform dispersion, thus obtaining an aqueous solution of La2O3 nanoparticles. Prepare a Ce(NO3)3·6H2O solution (0.05 mol / L). Add the Ce(NO3)3·6H2O solution to the aqueous solution of La2O3 nanoparticles at a molar ratio of La2O3 to CeO2 of 1:2. Then, while stirring in a 60°C water bath, slowly add urea solution (1 mol / L) and adjust the pH to 9.0. After reacting for 3 hours, the precipitate was separated by centrifugation, washed, and dried. The core-shell structure La2O3@CeO2 (shell thickness 3.5 nm) was formed by calcination in air at 500℃ for 2 hours. 1.2.3 Embedding of ZrO2 nanoclusters La2O3@CeO2 was dispersed in ethanol and ultrasonicated for 30 minutes to obtain a carrier suspension. Prepare a ZrOCl2 solution (0.075 mol / L); The ZrOCl2 solution was then slowly added dropwise to the carrier suspension and stirred at a constant temperature of 60°C. After adding ammonia water dropwise, continue stirring for 2 hours to allow Zr(OH)4 to be fully adsorbed in the CeO2 channels and on the surface; After stirring, centrifuge and wash three times with ethanol to remove free impurities; The Zr(OH)4 / La2O3@CeO2 precursor was obtained by vacuum drying at 80℃ for 12 hours. Finally, the Zr(OH)4 / La2O3@CeO2 precursor was placed in a tube furnace and calcined at 400℃ for 2 hours under a nitrogen atmosphere to convert Zr(OH)4 into ZrO2 nanoclusters with a particle size of 2nm. After cooling, a structural additive is obtained; 1.3 Preparation of acidity regulators Fluorination modification of mesoporous SiO2 support was carried out using a mixed solution of NH4F and HF (molar ratio 1:2); The pore size of mesoporous SiO2 is 10 nm; The mesoporous SiO2 support was impregnated in a fluorinated mixed solution and reacted at 60°C for 2 hours, then washed and dried. 1.4 Catalyst Composite The active component and the structural additive were mixed in supercritical CO2 fluid at a mass ratio of 1:12.5 for 1.5 hours to obtain a mixture; The mixture was then combined with an acid regulator by ultrasonic-assisted impregnation for 2 hours to obtain a crude product; Finally, the crude product was calcined at 400°C for 3 hours under a N2 atmosphere to obtain the final catalyst.

[0038] Comparative Example 1 The specific implementation steps are the same as in Example 3, except that Pt is not doped.

[0039] Comparative Example 2 The specific implementation steps are the same as in Example 3, except that the structural aid does not use a core-shell structure but a mixture of La2O3 and CeO2 as the structural aid.

[0040] Comparative Example 3 The specific implementation steps are the same as in Example 3, except that ZrO2 nanoclusters are not embedded in the CeO2 shell.

[0041] Experimental Example 1: Performance Testing of Catalysts in BDO Preparation 1.1 Experimental Objective To evaluate the catalytic performance of the catalysts prepared in Examples 1-3 and Comparative Examples 1-3 in the hydrogenation of BYD to BDO, and to verify their high conversion rate, selectivity and stability; 1.2 Experimental Conditions Reaction apparatus: Reactor, equipped with temperature control and online sampling system; Reaction materials: BYD, H2, deionized water Reaction parameters: Temperature: 180°C; Pressure: 4.0 MPa; Catalyst dosage: 50g; Stirring speed: 800 rpm; Reaction time: 6 hours; Analytical instruments: Gas chromatography analysis of product composition; TEM observation of the morphology of the catalyst after reaction; 1.3 Experimental Procedure Reaction process: After adding the catalyst and BYD solution to the reactor, H2 is passed through. Heat to 180°C, adjust the pressure to 4.0 MPa, and start timing; Take 5 mL samples every 1 hour, centrifuge, and then take the supernatant for GC analysis; Data Analysis: Calculate BYD conversion rate, BDO selectivity, and byproduct content; Stability test: The catalyst was reused 5 times, and the activity retention rate was measured. Anti-sintering properties: After the reaction, the catalyst was cooled under N2 protection, and the particle size change of the active component was observed by TEM. The final detection results are shown in Table 1 below. Table 1 Test Results

[0042] The experimental results above show that Example 3 exhibits the best catalytic performance, with a BYD conversion rate of 99.1%, a BDO selectivity of 94.7%, and a byproduct formation rate of only 3.8%. Furthermore, it maintains a 93.5% activity retention rate after five cycles, and the Cu particle size only increases to 12.8 nm after the reaction. This is because the nanoscale Pt-Cu-Zn-Al quaternary metal composite in Example 3, as the active component, significantly enhances the electronic and geometric effects of the catalytic center through precise doping of Pt atoms. Simultaneously, the Pt attracts… The addition not only modulates the d-band electronic structure of Cu and optimizes the adsorption strength of reaction intermediates, but also promotes the hydrogenation reaction by forming more interfacial defect sites. At the same time, the core-shell structured La2O3@CeO2 composite acts as a structural aid. Its unique core-shell configuration creates an efficient oxygen vacancy transport channel, realizing a dynamic "oxygen pump" function. During the reaction, this structure can not only remove carbon deposits in time through the active oxygen provided by the CeO2 shell, but also store excess oxygen species through the La2O3 core, thereby maintaining the cleanliness and activity of the catalyst surface. In contrast, Comparative Example 1, lacking Pt doping, suffered from insufficient electronic structure regulation of the active component, resulting in a significant decrease in conversion and selectivity, and an increase in byproducts to 10.2%. This demonstrates that the introduction of trace amounts of Pt plays an irreplaceable role in optimizing the electronic environment of the catalytic center. Comparative Example 2, using a simple physical mixture of La2O3 and CeO2 as a promoter, lacked the interfacial effect and directional oxygen transport capability of the core-shell structure, leading to a significant decrease in its catalytic performance and stability. After the reaction, the Cu particle size increased to 22.5 nm, fully demonstrating the unique advantage of the core-shell structure in inhibiting the sintering of the active component. Comparative Example 3, while retaining the core-shell structure, did not embed ZrO2 nanoclusters, resulting in weaker oxygen vacancy concentration and acid-base synergistic ability. This manifested as an increase in byproducts to 8.6%, and a lower activity retention rate than Example 3. This indicates that ZrO2 nanoclusters play a crucial role in improving the dynamic adaptability and stability of the catalyst.

[0043] 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 or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A catalyst for the synthesis of BDO, characterized in that, The catalyst comprises an active component, a structural aid, and an acid modifier; wherein the active component is a nano-sized Cu-Zn-Al ternary metal composite, and the particle size of the nano-sized Cu-Zn-Al ternary metal composite is 10-50 nm. The structural additive is a rare earth metal oxide, wherein the mass ratio of the rare earth metal oxide to the active component is 1:5:1:

20. The acid modifier is a fluoride-modified mesoporous SiO2 support with a pore size of 5-15 nm.

2. The catalyst according to claim 1, characterized in that, The molar ratio of Cu:Zn:Al in the nanoscale Cu-Zn-Al ternary metal composite is (40-60):(20-30):(10-30).

3. The catalyst according to claim 2, characterized in that, The nanoscale Cu-Zn-Al ternary metal composite is also doped with 0.1-0.5 wt% Pt atoms to form a nanoscale Pt-Cu-Zn-Al quaternary metal composite.

4. The catalyst according to claim 1, characterized in that, The rare earth metal oxide is a core-shell structured La2O3@CeO2 composite, in which CeO2 is the shell layer and La2O3 is the core layer, the shell layer thickness is 2-5 nm and the La2O3 particle size is 5-10 nm.

5. The catalyst according to claim 4, characterized in that, The CeO2 shell contains embedded ZrO2 nanoclusters, and the content of the ZrO2 nanoclusters is 5-10 wt%.

6. The catalyst according to claim 5, characterized in that, The ZrO2 nanoclusters have a particle size of 1-3 nm.

7. The catalyst according to claim 1, wherein the fluoride is a mixture of NH4F and HF.

8. The catalyst according to claim 7, characterized in that, The molar ratio of NH4F to HF is 1:1 to 1:

3.

9. A method for preparing a catalyst according to any one of claims 1-8, characterized in that, Includes the following steps: The active component was prepared by microwave-assisted co-precipitation and then mixed with a structural additive in supercritical CO2 fluid for 1-2 hours to obtain a mixture. The mixture was then combined with an acid regulator by ultrasonic-assisted impregnation for 1-3 hours to obtain the crude product. The crude product is roasted under an inert atmosphere to obtain the final product.

10. The preparation method according to claim 9, characterized in that, The microwave-assisted coprecipitation method uses a mixed solution of ammonium oxalate and ammonium bicarbonate as the precipitant, with a molar ratio of 1:1 to 1:3 and a pH value of 8.5 to 9.5.

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