A catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol, its preparation method and uses.

Abstract

This application provides a catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol, its preparation method, and its uses, relating to the field of catalysts. The catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol comprises an active component, a metal promoter, and a support; the active component is nano-Pt clusters, the metal promoter is W, and the support is a porous material; the active component and the metal promoter exist in the form of composite nano-clusters within the pores and on the outer surface of the support. The catalyst preparation method includes: mixing a water-soluble tungsten salt precursor, ethylene glycol, and water, adjusting the pH to strongly acidic to obtain a metal promoter solution; adding the Pt precursor to the metal promoter solution, and performing a photoprecipitation reaction under ultraviolet light irradiation to obtain a tungsten oxide-modified Pt nanoparticle sol; adding the support to the Pt nanoparticle sol, stirring, impregnating for adsorption, washing, and drying to obtain the catalyst. The catalyst provided in this application exhibits significantly superior selectivity for the target product cinnamyl alcohol.

Description

Technical Field

[0001] This application relates to the field of catalysts, and more particularly to a catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol, its preparation method, and its uses. Background Technology

[0002] Cinnamaldehyde, an important natural compound, possesses various biological activities such as antibacterial and antioxidant properties, and has clear application value in food preservation and safety, pharmaceuticals, daily chemical products, and agriculture. Among these, the selective hydrogenation of its C=O bond to prepare cinnamyl alcohol has been a subject of great interest in scientific research and industrial applications. This reaction is often considered an ideal model reaction for studying the relationship between catalyst surface structure and performance because the selectivity of the product is highly sensitive to the catalyst surface structure. Furthermore, its hydrogenation product, an unsaturated alcohol, has wide applications, not only in the perfume and sunscreen industries but also in the pharmaceutical field.

[0003] Patent application CN120827906A discloses a metal oxide-coated molecular sieve-supported catalyst, Pt@TiO2 / ZSM-5, for the hydrogenation of cinnamaldehyde, achieving a cinnamaldehyde conversion of 86.1% and a cinnamyl alcohol selectivity of 42.1%. Patent application CN118988315A proposes a Pt / Fe2O3-Al2O3 catalyst based on the SMSI effect, achieving a conversion of 88% and a cinnamyl alcohol selectivity of 88% in the same reaction. Patent application CN115837282A prepares Co / Ti3C2T using a chemical reduction method. x The catalyst selectively catalyzes the hydrogenation of C=O bonds through the synergistic effect between oxygen vacancies and active components, achieving a cinnamaldehyde conversion rate of 80-85% and a cinnamyl alcohol selectivity of 60-68%. Patent application CN113210008A developed a surface-modified Pt / HZSM-5 (alkali) catalyst by desilication and pore expansion of the catalyst through alkali treatment, achieving a cinnamaldehyde conversion rate as high as 95.8% and a cinnamyl alcohol selectivity of 90.7%. Furthermore, patent application CN113117674A prepared a two-dimensional sheet-like MgAl LDH support in one step using co-precipitation or hydrothermal methods, thereby obtaining a Pt / MgAl LDH catalyst. This support promotes high dispersion of Pt nanoparticles through the layer confinement effect and strong interaction between the metal support, ultimately achieving a cinnamaldehyde conversion rate of 79.8% and a cinnamyl alcohol selectivity of 82.1%.

[0004] Existing methods, such as impregnation, coprecipitation, and ion exchange, can enhance the selectivity and catalytic activity of cinnamyl alcohol by constructing metal-metal oxide interfaces on the catalyst surface. However, their control methods are often macroscopic, making it difficult to precisely design and maximize the density, distribution, and microstructure of interfacial active sites. These methods largely rely on the adjustment of macroscopic process parameters, and the interface formation process is influenced by a variety of factors, resulting in significant randomness in the construction of active sites. There is a lack of effective means for directional and controllable manipulation at the atomic or nanoscale. Therefore, this not only limits the effective density and utilization efficiency of interfacial active sites but also makes it difficult to establish a clear and predictable structure-activity relationship between the catalyst's structure and performance, thus hindering further performance improvement and in-depth system optimization. Summary of the Invention

[0005] The purpose of this application is to provide a catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol, a preparation method thereof, and its uses, in order to solve the above-mentioned problems.

[0006] To achieve the above objectives, this application adopts the following technical solution: A catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol comprises an active component, a metal promoter, and a support. The active component is a nano-Pt cluster, the metal additive corresponds to the metal W, and the support is a porous material. The active component and the metal additive exist in the form of composite nanoclusters inside the pores and on the outer surface of the carrier.

[0007] Preferably, the carrier is one or more of amorphous silica, MFI molecular sieve composed of pure silicon, γ-alumina, and titanium dioxide.

[0008] Preferably, the catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol satisfies one or more of the following conditions: (1) The content of the active component is 0.2%-0.4% of the mass of the carrier; (2) The content of the metal additive is 0.3%-0.5% of the mass of the carrier; Preferably, the catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol satisfies one or more of the following conditions: (1) The average particle size of the nano-Pt clusters is 2.1-2.5 nm; (2) The specific surface area of ​​the carrier is 200-500 m². 2 / g.

[0009] This application also provides a method for preparing the catalyst described above for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol, comprising: A solution of metal additives is obtained by mixing a water-soluble tungsten salt precursor, ethylene glycol and water, and adjusting the pH to strongly acidic. The Pt precursor was added to the metal additive solution, and a photoprecipitation reaction was carried out under ultraviolet light irradiation to obtain Pt nanoparticle sol modified with tungsten oxide. The carrier was added to the Pt nanoparticle sol, and the mixture was stirred, impregnated and adsorbed, washed and dried to obtain the catalyst.

[0010] Preferably, the method for preparing the catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol satisfies one or more of the following conditions: (1) The water-soluble tungsten salt precursor is selected from one or more of sodium tungstate, ammonium metatungstate, ammonium tungstate, and potassium tungstate; sodium tungstate is preferred. (2) The pH adjustment is performed using sulfuric acid; (3) The pH value corresponding to the strong acidity is 1-2; (4) After adjusting the pH to strong acidity, ultrasonic dispersion is also included, and the ultrasonic dispersion time is 0.5-2h.

[0011] Preferably, the method for preparing the catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol satisfies one or more of the following conditions: (1) The ultraviolet light is UVA light with a wavelength of 320-400nm; (2) The Pt precursor is selected from one or more of chloroplatinic acid, sodium chloroplatinate, potassium chloroplatinate, and ammonium chloroplatinate; preferably chloroplatinic acid; (3) The stirring time is 8-15 hours, and the stirring speed is 300-1000 r / min; (4) The drying temperature is 50-100℃ and the time is 4-12h.

[0012] This application also provides the use of the catalyst described above for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol, for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol.

[0013] Preferably, the reaction temperature for the selective hydrogenation of cinnamaldehyde to prepare cinnamyl alcohol is 120-150℃, and the reaction pressure is 2.5-5MPa.

[0014] Preferably, the reaction solvent for the selective hydrogenation of cinnamaldehyde to prepare cinnamyl alcohol is selected from one or more of isopropanol, methanol, ethanol, or toluene; And / or, The selective hydrogenation of cinnamaldehyde to prepare cinnamyl alcohol is carried out in a batch reaction using a reactor, or in a fixed bed, fluidized bed, or moving bed.

[0015] Compared with the prior art, the beneficial effects of this application include: The catalyst provided in this application achieves the co-reduction of Pt and WO3 via ultraviolet light. x The synergistic deposition and nucleation of species at the nanoscale enables the precise and maximized construction of high-density Pt-W interfacial active sites. The invented catalyst exhibits strong metal-support interactions, and its hydrogen spillover effect significantly reduces the reduction temperature of W species (approximately 60 °C lower than the impregnation method). Under the reaction conditions, it readily forms abundant oxygen vacancies, resulting in superior reaction kinetics with an apparent activation energy of only 31.2 kJ / mol. In the selective hydrogenation of cinnamaldehyde, it demonstrates significantly superior selectivity for the target product cinnamyl alcohol, far exceeding that of comparative samples prepared by the traditional impregnation method, successfully solving the core problem of low C=O bond selectivity.

[0016] In the catalyst preparation method provided in this application, WO x (Tungsten oxide) played an effective stabilizing role, resulting in uniformly dispersed Pt nanoparticles, overcoming the problem of metal agglomeration in traditional methods.

[0017] The catalyst preparation method provided in this application features a photodeposition process with mild conditions, simple operation, and short processing time. It can be completed at ambient pressure and near room temperature, providing a reliable path for the large-scale preparation of high-performance interfacial catalysts and their industrial application. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0019] Figure 1 This is a schematic diagram of the XRD crystal structure of the heterogeneous catalyst in Example 1 of this application; Figure 2 This is a TEM image of the heterogeneous catalyst of Example 1 of this application; Figure 3 This is the CO-IR spectrum of the heterogeneous catalyst in Example 1 of this application. Detailed Implementation

[0020] To better illustrate the technical solution provided in this application, the technical solution will be described in its entirety before the embodiments, as follows: A catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol comprises an active component, a metal promoter, and a support. The active component is a nano-Pt cluster, the metal additive corresponds to the metal W, and the support is a porous material. The active component and the metal additive exist in the form of composite nanoclusters inside the pores and on the outer surface of the carrier.

[0021] In one optional embodiment, the carrier is one or more of amorphous silica, MFI molecular sieve composed of pure silicon, γ-alumina, and titanium dioxide.

[0022] In an optional embodiment, the catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol satisfies one or more of the following conditions: (1) The content of the active component is 0.2%-0.4% of the mass of the carrier; Optionally, the content of the active component is any value between 0.2%, 0.3%, 0.4% or 0.2%-0.4% of the mass of the carrier; (2) The content of the metal additive is 0.3%-0.5% of the mass of the carrier; Optionally, the content of the metal additive is any value between 0.3%, 0.4%, 0.5% or 0.3%-0.5% of the mass of the carrier; In an optional embodiment, the catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol satisfies one or more of the following conditions: (1) The average particle size of the nano-Pt clusters is 2.1-2.5 nm; Optionally, the average particle size of the nano-Pt clusters can be any value between 2.1 nm, 2.2 nm, 2.3 nm, 2.4 nm, 2.5 nm, or 2.1-2.5 nm. (2) The specific surface area of ​​the carrier is 200-500 m². 2 / g.

[0023] Optionally, the specific surface area of ​​the carrier can be 200 m². 2 / g、300m 2 / g、400m 2 / g、500m 2 / g or 200-500m 2 Any value between / g.

[0024] This application also provides a method for preparing the catalyst described above for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol, comprising: A solution of metal additives is obtained by mixing a water-soluble tungsten salt precursor, ethylene glycol and water, and adjusting the pH to strongly acidic. The Pt precursor was added to the metal additive solution, and a photoprecipitation reaction was carried out under ultraviolet light irradiation to obtain Pt nanoparticle sol modified with tungsten oxide. The carrier was added to the Pt nanoparticle sol, and the mixture was stirred, impregnated and adsorbed, washed and dried to obtain the catalyst.

[0025] This invention proposes an innovative photodeposition strategy aimed at achieving Pt-WO3 deposition. x Precise and maximized interface construction. The core idea of ​​this method is to induce co-reduction of Pt and W precursors in the liquid phase using ultraviolet light, promoting the simultaneous nucleation and growth of the two species at the atomic / nanoscale, thereby forcing them to form a closely adjacent composite structure in space. This process effectively overcomes the inherent defects of traditional stepwise loading methods, such as the tendency for metal and additive species to aggregate independently and limited interfacial contact, ensuring high-density and high-uniformity Pt-WO from the source. x The formation of an active interface. Furthermore, by simply adjusting the W / Pt feed ratio in the precursor, the W content at the interface can be systematically adjusted. x The degree of coverage and electronic interactions enable precise "tailoring" of the interface structure and catalytic performance. This preparation method, which combines directional construction and convenient controllability, provides new research ideas for the design and controllable preparation of high-efficiency catalysts.

[0026] The catalyst of this application is prepared by a combination of photodeposition and impregnation methods. The support in the catalyst has a significantly large specific surface area and a porous structure that facilitates diffusion, effectively loading and anchoring the clusters of active components and promoters, and inhibiting their migration and loss. Furthermore, the preparation method of this invention can effectively disperse the promoters and their interaction with the active components, resulting in better electronic modulation and improved overall catalyst performance, demonstrating significant potential for industrial applications.

[0027] Cinnamaldehyde molecules contain both C=C and C=O bonds. Selective hydrogenation of the C=O bonds is thermodynamically and kinetically more unfavorable than that of the C=C bonds. Pt catalysts themselves have a high affinity for the C=C bonds, easily leading to over-hydrogenation and the formation of saturated alcohol byproducts. Therefore, developing Pt-based catalysts that can precisely guide the reaction pathway and preferentially activate and hydrogenate polar C=O bonds has become a core problem urgently needing to be solved in this field.

[0028] The purpose of this invention is to provide a catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol, its preparation method, and its application. By constructing an interface between Pt and a metal oxide or L acid, H2 and the substrate are adsorbed to activate hydrogen and cinnamaldehyde, respectively. Subsequently, the activated hydrogen achieves selective hydrogenation of C=O at the interface through hydrogen overflow. The synergistic effect of the two components can often balance conversion and selectivity.

[0029] In an optional embodiment, the method for preparing the catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol satisfies one or more of the following conditions: (1) The water-soluble tungsten salt precursor is selected from one or more of sodium tungstate, ammonium metatungstate, ammonium tungstate, and potassium tungstate; sodium tungstate is preferred. (2) The pH adjustment is performed using sulfuric acid; (3) The pH value corresponding to the strong acidity is 1-2 (which can be any value between 1, 1.5, 2 or 1-2). (4) After adjusting the pH to strong acidity, ultrasonic dispersion is also included. The ultrasonic dispersion time is 0.5-2h (which can be any value between 0.5h, 1h, 1.5h, 2h or 0.5-2h).

[0030] In an optional embodiment, the method for preparing the catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol satisfies one or more of the following conditions: (1) The ultraviolet light is UVA light with a wavelength of 320-400nm (which can be 320nm, 330nm, 340nm, 350nm, 360nm, 370nm, 380nm, 390nm, 400nm or any value between 320-400nm); (2) The Pt precursor is selected from one or more of chloroplatinic acid, sodium chloroplatinate, potassium chloroplatinate, and ammonium chloroplatinate; preferably chloroplatinic acid; (3) The stirring time is 8-15h (which can be any value between 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h or 8-15h), and the stirring speed is 300-1000r / min (which can be any value between 300r / min, 400r / min, 500r / min, 600r / min, 700r / min, 800r / min, 900r / min, 1000r / min or 300-1000r / min). (4) The drying temperature is 50-100℃ (can be any value between 50℃, 60℃, 70℃, 80℃, 90℃, 100℃ or 50-100℃), and the time is 4-12h (can be any value between 4h, 6h, 8h, 10h, 12h or 4-12h).

[0031] This application also provides the use of the catalyst described above for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol, for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol.

[0032] In an optional embodiment, the reaction temperature for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol is 120-150°C (which can be any value between 120°C, 130°C, 140°C, 150°C, or 120-150°C), and the reaction pressure is 2.5-5 MPa (which can be any value between 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, 5 MPa, or 2.5-5 MPa).

[0033] In an optional embodiment, the reaction solvent for the selective hydrogenation of cinnamaldehyde to prepare cinnamyl alcohol is selected from one or more of isopropanol, methanol, ethanol, or toluene; And / or, The selective hydrogenation of cinnamaldehyde to prepare cinnamyl alcohol is carried out in a batch reaction using a reactor, or in a fixed bed, fluidized bed, or moving bed.

[0034] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0035] In this embodiment, the product analysis method used was Agilent chromatography. The specific detection methods for cinnamaldehyde, cinnamyl alcohol, and other products were as follows: The chromatographic column used was an HP-5, 30m × 320μm × 0.25μm, connected to a FID detector. The detector temperature was 300℃, the air flow rate was 400mL / min, and the hydrogen flow rate was 30mL / min. The column oven temperature program was: initial temperature 40℃, retention time 3min, temperature ramp rate 10℃ / min, final temperature 280℃, retention time 8min.

[0036] Example 1 The catalyst in this embodiment consists of 0.35 wt% Pt, 0.4 wt% W, and 99.25 wt% amorphous silica, denoted as Cat1#, and is prepared as follows: (1) Weigh 0.036g of water-soluble sodium tungstate and dissolve it in 100g of deionized water, add 20g of ethylene glycol, adjust the pH of the solution to between 1 and 2 with 10% dilute sulfuric acid, and then ultrasonically disperse it for 30min.

[0037] (2) Under UVA ultraviolet light irradiation, weigh 0.047g of chloroplatinic acid and add it to step (1) to cause a photodeposition reaction to generate WO3. x Modified Pt nanoparticle sol.

[0038] (3) Weigh 5g of silica support and add it to step (2) above. Stir for 1 hour, impregnate and adsorb, and wash. Dry at 60℃ for 8 hours to obtain the heterogeneous catalyst WO. x -Pt / SiO2-UV. Designated as catalyst Cat1#.

[0039] Electron microscopy analysis showed that the average size of the Pt clusters in catalyst Cat1# was approximately 2.29 nm.

[0040] Figure 1 This is a schematic diagram of the XRD crystal structure of the heterogeneous catalyst in Example 1. Figure 2 This is a TEM image of the heterogeneous catalyst in Example 1. Figure 3 The image shows the CO-IR spectrum of the heterogeneous catalyst in Example 1.

[0041] Using Cat1# as a catalyst, cinnamaldehyde as a raw material, and hydrogen as the reactant, a hydrogenation reaction was carried out as follows: 0.1 g of heterogeneous catalyst Cat1#, 1 mmol of cinnamaldehyde, 0.5 mmol of n-nonane, and 5 mL of isopropanol were sequentially added to a 50 mL stainless steel autoclave equipped with a magnetic stirrer. The reactor was purged three times with hydrogen, and then purged with 3 MPa H2. The reaction was stirred at 130 °C and 1000 rpm for 3 h to obtain the reaction product, which was analyzed online by gas chromatography.

[0042] Example 2 The catalyst in this embodiment consists of 0.2 wt% Pt, 0.6 wt% W, and 99 wt% Silicalite-1, denoted as Cat2#, and was prepared as follows: (1) Weigh 0.054g of water-soluble ammonium tungstate and dissolve it in 100g of deionized water, add 20g of ethylene glycol, adjust the pH of the solution to between 1 and 2 with 10% dilute sulfuric acid, and then ultrasonically disperse it for 60min.

[0043] (2) Under UVA ultraviolet light irradiation, 0.027g of ammonium chloroplatinate was weighed and added to step (1) to cause a photodeposition reaction to generate WO3. x Modified Pt nanoparticle sol.

[0044] (3) Weigh 5g of Silicalite-1 support and add it to step (2) above. Stir for 2 hours, impregnate and adsorb, and wash. Dry at 80℃ for 10 hours to obtain the heterogeneous catalyst WO. x -Pt / Silicalite-1-UV. Designated as catalyst Cat2#.

[0045] Electron microscopy analysis showed that the average size of the Pt clusters in the catalyst Cat2# was approximately 2.5 nm.

[0046] Using Cat2# as a catalyst, a hydrogenation reaction was carried out with cinnamaldehyde as the raw material and hydrogen as the reactant, as detailed below: 0.1 g of heterogeneous catalyst Cat2#, 1 mmol of cinnamaldehyde, 0.5 mmol of n-nonane, and 5 mL of isopropanol were sequentially added to a 50 mL stainless steel autoclave equipped with a magnetic stirrer. The reactor was purged three times with hydrogen, and then purged with 3 MPa H2. The reaction was stirred at 130 °C and 1000 rpm for 3 h to obtain the reaction product, which was analyzed online by gas chromatography.

[0047] Example 3 The catalyst in this embodiment has the composition of 0.45wt% Pt, 0.45wt% W and 99.1wt% γ-Al2O3, denoted as Cat3#, and is prepared according to the following method: (1) Weigh 0.046g of water-soluble potassium tungstate and dissolve it in 100g of deionized water, add 20g of ethylene glycol, adjust the pH of the solution to between 1 and 2 with 10% dilute sulfuric acid, and then ultrasonically disperse it for 60min.

[0048] (2) Under UVA ultraviolet light irradiation, 0.060g of ammonium chloroplatinate was weighed and added to step (1) to cause a photodeposition reaction to generate WO3. x Modified Pt nanoparticle sol.

[0049] (3) Weigh 5g of γ-Al2O3 support and add it to step (2) above. Stir for 3h, impregnate and adsorb, and wash. Dry at 70℃ for 12h to obtain the heterogeneous catalyst WO. x -Pt / γ-Al2O3-UV. Designated as catalyst Cat3#.

[0050] Electron microscopy analysis showed that the average size of the Pt clusters in the catalyst Cat3# was approximately 3.1 nm.

[0051] Using Cat3# as a catalyst, cinnamaldehyde as a raw material, and hydrogen as the reactant, a hydrogenation reaction was carried out as follows: 0.1 g of heterogeneous catalyst Cat3#, 1 mmol of cinnamaldehyde, 0.5 mmol of n-nonane, and 5 mL of isopropanol were sequentially added to a 50 mL stainless steel autoclave equipped with a magnetic stirrer. The reactor was purged three times with hydrogen, and then purged with 3 MPa H2. The reaction was stirred at 130 °C and 1000 rpm for 3 h to obtain the reaction product, which was analyzed online by gas chromatography.

[0052] Example 4 The catalyst in this embodiment has a composition of 0.3 wt% Pt, 0.5 wt% W and 99.2 wt% TiO2, denoted as Cat4#, and is prepared as follows: (1) Weigh 0.045g of water-soluble sodium tungstate and dissolve it in 100g of deionized water, add 20g of ethylene glycol, adjust the pH of the solution to between 1 and 2 with 10% dilute sulfuric acid, and then ultrasonically disperse it for 60min.

[0053] (2) Under UVA ultraviolet light irradiation, 0.0405g of ammonium chloroplatinate was weighed and added to step (1) to cause a photodeposition reaction to generate WO3. x Modified Pt nanoparticle sol.

[0054] (3) Weigh 5g of TiO2 support and add it to step (2) above. Stir for 2 hours, impregnate and adsorb, and wash. Dry at 80℃ for 10 hours to obtain the heterogeneous catalyst WO. x -Pt / TiO2-UV. Designated as catalyst Cat4#.

[0055] Electron microscopy analysis showed that the average size of the Pt clusters in the catalyst Cat4# was approximately 2.7 nm.

[0056] Using Cat4# as a catalyst, a hydrogenation reaction was carried out with cinnamaldehyde as the raw material and hydrogen as the reactant, as detailed below: 0.1 g of heterogeneous catalyst Cat4#, 1 mmol of cinnamaldehyde, 0.5 mmol of n-nonane, and 5 mL of isopropanol were sequentially added to a 50 mL stainless steel autoclave equipped with a magnetic stirrer. The reactor was purged three times with hydrogen, and then purged with 3 MPa H2. The reaction was stirred at 130 °C and 1000 rpm for 3 h to obtain the reaction product, which was analyzed online by gas chromatography.

[0057] Comparative Example 1 The comparative catalyst, designated Comparative Example Cat1#, consists of 0.35 wt% Pt, 0.4 wt% W, and 99.25 wt% amorphous silica, and was prepared as follows: (1) Weigh 0.036g of water-soluble sodium tungstate and 0.047g of chloroplatinic acid, and dissolve them in 10g of deionized water to obtain a mixed solution.

[0058] (2) Weigh 5g of silica support and add it to the above step (1), stir for 1h, impregnate and adsorb, and wash. Then dry at 60℃ for 8h to obtain the heterogeneous catalyst WO. x -Pt / SiO2- impregnation method. This is denoted as Comparative Example Cat1#.

[0059] Electron microscopy analysis showed that the average size of the Pt clusters in the catalyst comparison Cat1# was approximately 3.1 nm.

[0060] Using Cat1# as a catalyst, a hydrogenation reaction was carried out with cinnamaldehyde as the raw material and hydrogen as the reactant, as detailed below: 0.1 g of the heterogeneous catalyst (comparative example Cat1#), 1 mmol of cinnamaldehyde, 0.5 mmol of n-nonane, and 5 mL of isopropanol were sequentially added to a 50 mL stainless steel autoclave equipped with a magnetic stirrer. The reactor was purged three times with hydrogen, and then purged with 3 MPa H2. The reaction was stirred at 130 °C and 1000 rpm for 3 h to obtain the reaction product, which was analyzed online by gas chromatography.

[0061] Comparative Example 2 The comparative catalyst, denoted as Comparative Example Cat2#, consists of 0.45 wt% Pt, 0.45 wt% W, and 99.1 wt% γ-Al2O3, and was prepared as follows: (1) Weigh 0.046g of water-soluble potassium tungstate and 0.060g of chloroplatinic acid, and dissolve them in 10g of deionized water to obtain a mixed solution.

[0062] (2) Weigh 5g of γ-Al2O3 support and add it to the above step (1), stir for 3h, impregnate and adsorb, and wash. Then dry at 70℃ for 12h to obtain the heterogeneous catalyst WO. x -Pt / γ-Al2O3- impregnation method. This is denoted as Comparative Example Cat2#.

[0063] Electron microscopy analysis showed that the average size of the Pt clusters in the catalyst comparison Cat2# was approximately 3.4 nm.

[0064] Using Cat2# as a catalyst, a hydrogenation reaction was carried out with cinnamaldehyde as the raw material and hydrogen as the reactant. Specifically, 0.1 g of heterogeneous catalyst Cat3#, 1 mmol of cinnamaldehyde, 0.5 mmol of n-nonane, and 5 mL of isopropanol were sequentially added to a 50 mL stainless steel autoclave equipped with a magnetic stirrer. The reactor was purged three times with hydrogen, and then 3 MPa H2 was introduced. The reaction was stirred at 130 °C and 1000 rpm for 3 h to obtain the reaction product, which was analyzed online by gas chromatography.

[0065] Comparative Example 3 The comparative catalyst, designated Comparative Example Cat3#, consists of 0.35 wt% Pt and 99.65 wt% amorphous silica, and was prepared as follows: (1) Weigh 0.47 g of chloroplatinic acid and dissolve it in 10 g of deionized water to obtain a mixed solution.

[0066] (2) Weigh 5g of silica support and add it to the above step (1) and stir for 1h, impregnate and adsorb, and wash. Then dry at 60℃ for 8h to obtain the heterogeneous catalyst Pt / SiO2-impregnation method. It is denoted as comparative example Cat1#.

[0067] Electron microscopy analysis showed that the average size of the Pt clusters in the comparative catalyst Cat1# was approximately 2.7 nm. Using Cat3# as a catalyst, a hydrogenation reaction was carried out with cinnamaldehyde as the raw material and hydrogen as the reactant. Specifically, 0.1 g of the heterogeneous catalyst Cat3#, 1 mmol of cinnamaldehyde, 0.5 mmol of n-nonane, and 5 mL of isopropanol were sequentially added to a 50 mL stainless steel autoclave equipped with a magnetic stirrer. The reactor was purged three times with hydrogen, and then 3 MPa H2 was introduced. The reaction was stirred at 130 °C and 1000 rpm for 3 h to obtain the reaction product, which was analyzed online by gas chromatography.

[0068] Comparative Example 4 The comparative catalyst, designated Comparative Example Cat4#, consists of 0.35 wt% Pt, 0.4 wt% W, and 99.25 wt% amorphous silica, and was prepared as follows: (1) Weigh 0.036g of water-soluble sodium tungstate and dissolve it in 100g of deionized water, add 20g of ethanol, adjust the pH of the solution to between 1 and 2 with 10% dilute sulfuric acid, and then ultrasonically disperse it for 30min.

[0069] (2) Under UVA ultraviolet light irradiation, weigh 0.047g of chloroplatinic acid and add it to step (1) to cause a photodeposition reaction to generate WO3. x Modified Pt nanoparticle sol.

[0070] Electron microscopy analysis showed that the average size of the Pt clusters in the catalyst comparison Cat4# was approximately 4.1 nm.

[0071] Using comparative example Cat4# as a catalyst, a hydrogenation reaction was carried out with cinnamaldehyde as the raw material and hydrogen as the reactant. Specifically, 0.1 g of the heterogeneous catalyst (comparative example Cat4#), 1 mmol of cinnamaldehyde, 0.5 mmol of n-nonane, and 5 mL of isopropanol were sequentially added to a 50 mL stainless steel autoclave equipped with a magnetic stirrer. The reactor was purged three times with hydrogen, and then purged with 3 MPa H2. The reaction was stirred at 130 °C and 1000 rpm for 3 h to obtain the reaction product, which was analyzed online by gas chromatography.

[0072] Comparative Example 5 The comparative catalyst, designated Comparative Example Cat5#, consists of 0.35 wt% Pt, 0.4 wt% W, and 99.25 wt% amorphous silica, and was prepared as follows: (1) Weigh 0.036g of water-soluble sodium tungstate and dissolve it in 100g of deionized water, add 20g of ethylene glycol, adjust the pH of the solution to below 1 with 10% dilute sulfuric acid, and then ultrasonically disperse it for 30min.

[0073] (2) Under UVA ultraviolet light irradiation, weigh 0.047g of chloroplatinic acid and add it to step (1) to cause a photodeposition reaction to generate WO3. x Modified Pt nanoparticle sol.

[0074] Electron microscopy analysis showed that the average size of the Pt clusters in the catalyst comparison Cat5# was approximately 10.5 nm.

[0075] Using comparative example Cat5# as a catalyst, a hydrogenation reaction was carried out with cinnamaldehyde as the raw material and hydrogen as the reactant. Specifically, 0.1 g of the heterogeneous catalyst (comparative example Cat5#), 1 mmol of cinnamaldehyde, 0.5 mmol of n-nonane, and 5 mL of isopropanol were sequentially added to a 50 mL stainless steel autoclave equipped with a magnetic stirrer. The reactor was purged three times with hydrogen, and then purged with 3 MPa H2. The reaction was stirred at 130 °C and 1000 rpm for 3 h to obtain the reaction product, which was analyzed online by gas chromatography.

[0076] The results of the catalysts obtained in the examples and comparative examples catalyzing the hydrogenation of cinnamaldehyde in a fixed-bed reactor are shown in Table 1 below: Table 1. Results of catalytic hydrogenation of cinnamaldehyde using various catalysts in a fixed-bed reactor. As shown in Table 1 above, the Pt fabrication method based on ultraviolet light deposition provided by this invention... WO x The heterogeneous catalyst at the interface exhibited significantly superior catalytic performance compared to conventional methods in the selective hydrogenation of cinnamaldehyde. Compared to Comparative Example 1 (48% conversion, 42% selectivity) and Comparative Example 2 (51% conversion, 37% selectivity) prepared by conventional impregnation methods, Example 1 of this invention (99% conversion, 93% selectivity) achieved a substantial improvement in both conversion and selectivity, demonstrating the effectiveness of the UV co-reduction strategy in constructing high-density, highly active Pt. The unique advantages of W in terms of interface properties. Furthermore, Comparative Example 3 (conversion 11%, selectivity 47%) lacking the auxiliary agent W showed a significant decrease in activity, indicating that W species are crucial for activating C=O bonds and promoting hydrogen spillover; Comparative Example 4 (conversion 34%, selectivity 41%) using ethanol instead of ethylene glycol showed a significant deterioration in performance, indicating the key role of ethylene glycol in the precursor dispersion and reduction process during photodeposition; while Comparative Example 5 (conversion 3%, selectivity 27%) prepared under strongly acidic conditions (pH < 1) was almost inactive, further highlighting the pH range (1 < 1) defined in this invention. 2) Importance of controlling nanoparticle size and interfacial structure. In summary, the catalyst of this invention has the characteristics of high activity, high selectivity and strong structural controllability, and has important industrial application value in the field of green synthesis of cinnamyl alcohol.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 therein. Such 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 this application.

Claims

1. A catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol, characterized in that, Includes active ingredients, metal additives, and carriers; The active component is a nano-Pt cluster, the metal additive corresponds to the metal W, and the support is a porous material. The active component and the metal additive exist in the form of composite nanoclusters inside the pores and on the outer surface of the carrier.

2. The catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol according to claim 1, characterized in that, The carrier is one or more of the following: amorphous silica, MFI molecular sieve composed of pure silicon, γ-alumina, and titanium dioxide.

3. The catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol according to claim 1, characterized in that, One or more of the following conditions must be met: (1) The content of the active component is 0.2%-0.4% of the mass of the carrier; (2) The content of the metal additive is 0.3%-0.5% of the mass of the carrier.

4. The catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol according to any one of claims 1-3, characterized in that, One or more of the following conditions must be met: (1) The average particle size of the nano-Pt clusters is 2.1-2.5 nm; (2) The specific surface area of ​​the carrier is 200-500 m². 2 / g.

5. A method for preparing the catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol according to any one of claims 1-4, characterized in that, include: A solution of metal additives is obtained by mixing a water-soluble tungsten salt precursor, ethylene glycol and water, and adjusting the pH to strongly acidic. The Pt precursor was added to the metal additive solution, and a photoprecipitation reaction was carried out under ultraviolet light irradiation to obtain Pt nanoparticle sol modified with tungsten oxide. The carrier was added to the Pt nanoparticle sol, and the mixture was stirred, impregnated and adsorbed, washed and dried to obtain the catalyst.

6. The method for preparing the catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol according to claim 5, characterized in that, One or more of the following conditions must be met: (1) The water-soluble tungsten salt precursor is selected from one or more of sodium tungstate, ammonium metatungstate, ammonium tungstate, and potassium tungstate; sodium tungstate is preferred. (2) The pH adjustment is performed using sulfuric acid; (3) The pH value corresponding to the strong acidity is 1-2; (4) After adjusting the pH to strong acidity, ultrasonic dispersion is also included, and the ultrasonic dispersion time is 0.5-2h.

7. The method for preparing the catalyst for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol according to claim 5 or 6, characterized in that, One or more of the following conditions must be met: (1) The ultraviolet light is UVA light with a wavelength of 320-400nm; (2) The Pt precursor is selected from one or more of chloroplatinic acid, sodium chloroplatinate, potassium chloroplatinate, and ammonium chloroplatinate; preferably chloroplatinic acid; (3) The stirring time is 8-15 hours, and the stirring speed is 300-1000 r / min; (4) The drying temperature is 50-100℃ and the time is 4-12h.

8. The use of the catalyst according to any one of claims 1-4 for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol, characterized in that, Used for the selective hydrogenation of cinnamaldehyde to prepare cinnamyl alcohol.

9. The use of the catalyst according to claim 8 for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol, characterized in that, The selective hydrogenation of cinnamaldehyde to prepare cinnamyl alcohol is carried out at a reaction temperature of 120-150℃ and a reaction pressure of 2.5-5MPa.

10. The use of the catalyst according to claim 8 or 9 for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol, characterized in that, The reaction solvent for the selective hydrogenation of cinnamaldehyde to prepare cinnamyl alcohol is selected from one or more of isopropanol, methanol, ethanol, or toluene; And / or, The selective hydrogenation of cinnamaldehyde to prepare cinnamyl alcohol is carried out in a batch reaction using a reactor, or in a fixed bed, fluidized bed, or moving bed.

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