CN117258803A - Mesoporous cerium oxide loaded PdCu nanoparticle catalyst and preparation method and application thereof - Google Patents

Abstract

The invention discloses a mesoporous cerium oxide supported PdCu nanoparticle catalyst and its preparation method and application, and belongs to the technical field of catalysts. The present invention uses melamine and terephthalaldehyde to carry out aldehyde-amine condensation polymerization reaction to obtain a porous organic polymer template material; the pores of the porous organic polymer template material are filled with PdCu alloy nanoparticles and cerium salt precursors, and the template agent is removed by roasting to obtain Mesoporous cerium oxide supported PdCu nanoparticle catalyst. The catalyst can be used to catalyze the selective hydrogenation of acetylenic alcohols to produce enols. The conversion rate of acetylenic alcohols can be as high as 100%, the selectivity of enols is higher than 99%, and the catalyst can be stably used at least 5 times.

Description

A kind of mesoporous cerium oxide supported PdCu nanoparticle catalyst and its preparation method and application

Technical field

The invention belongs to the technical field of catalysts, and in particular relates to a mesoporous cerium oxide supported PdCu nanoparticle catalyst and its preparation method and application.

Background technique

The selective hydrogenation reaction of acetylenic alcohols is to synthesize linalool, isophytol, 2-methyl-3-buten-2-ol, cis-3-hexen-1-ol (leaf alcohol), cis- -2-Butene-1,4-diol and other enols are the main pathway, and these enols are key intermediates in the industrial production of high value-added pharmaceuticals, agricultural chemicals, and flavors and fragrances. However, the process of obtaining enols through selective hydrogenation of acetylenic alcohols is very difficult. In addition to protecting other functional groups such as C-OH in the acetylenic alcohol molecules, it is more important to avoid excessive hydrogenation of C≡C to C-C, and selectively Generate C=C.

In recent years, due to the attention and research on the selective hydrogenation reaction of alkynes and acetylenic alcohols, various metal-supported catalysts (such as Pd, Pt and Ni, etc.) have been developed to catalyze such reactions (Catalysis Science & Technology, 2020, 10(2):327-331). However, these metal-supported catalysts usually have larger metal nanoparticles with a wide range of particle size distribution, so the metal active sites expose different crystal facets with different atomic structures. Due to the different interactions between reactants and metal active sites during alkynyl hydrogenation, the heterogeneity of the active sites will lead to poor selectivity of the catalytic reaction (Chemical Reviews, 2020, 120(2): 683 -733).

Mesoporous materials are the key carrier materials for constructing supported hydrogenation catalysts. Mesoporous cerium oxide nanomaterials have high specific surface area, rich porous structure, and have important applications in industrial catalysis, fuel cells, sensitive devices and other fields. High surface area mesoporous cerium oxide materials are currently mainly prepared by the following methods: mesoporous carbon or mesoporous SiO ₂ as a hard template, pluronic P123 or F127 as a soft template, sol-gel method, and hydrothermal synthesis method. Porous cerium oxide carrier materials (Journal of Colloid and Interface Science, 436 (2014) 52-62); the current preparation methods of these mesoporous cerium oxide carriers still have problems such as large waste liquid discharge during the preparation process and cumbersome preparation.

In view of the above-mentioned technical bottlenecks in the selective hydrogenation of acetylenic alcohols and the current research field of high specific surface area mesoporous cerium oxide catalytic materials, an efficient mesoporous cerium oxide supported catalyst was developed for the highly selective catalytic hydrogenation of acetylenic alcohols into enols. of great significance.

Contents of the invention

In view of the problems existing in the above-mentioned prior art, the present invention proposes a mesoporous cerium oxide supported PdCu nanoparticle catalyst and its preparation method and application. The present invention uses a porous organic polymer as a template, pre-fills PdCu alloy nanoparticles and cerium salt precursors in the pores, removes the polymer template through roasting, and then reduces to prepare a PdCu alloy anchored in mesoporous cerium oxide pores. Catalyst, and a method for selectively catalyzing the hydrogenation of acetylenic alcohols to prepare enols, the reaction equation is as follows:

In order to achieve the above objects, the present invention provides the following technical solutions:

Technical solution one: a mesoporous cerium oxide supported PdCu nanoparticle catalyst, the mass ratio of each component in the mesoporous cerium oxide supported PdCu nanoparticle catalyst is Pd:Cu:CeO ₂ =(1-4):(1 -4):100. The mesoporous cerium oxide supported PdCu nanoparticle catalyst has a specific surface area of 68m ² /g, a pore size distribution of 5-60nm, and a pore volume of 0.3cm ³ /g.

"Active site isolation" is to homogenize the metal active sites by isolating metal active sites to suppress side reactions that may be caused by metal aggregation to improve the selectivity of the catalyst during catalytic reactions. The present invention adjusts the composition and structure of metal active sites in the catalyst by using the second metal copper as a regulator. In bimetallic or multimetallic nanoparticles, the interaction between components changes the composite structure of the catalytic site and changes the electronic structure of the active metal through charge transfer and other forms. These two influencing factors determine the combination mode and strength of reactants/intermediates/products at the active site, which directly affects the selectivity of the catalyst. As a metal with high electron density and low cost, the present invention uses Cu as the second metal doping to change the properties of the active metal.

Technical Solution 2: A method for preparing a mesoporous cerium oxide-supported PdCu nanoparticle catalyst, using melamine and terephthalaldehyde to perform an aldehyde-amine polycondensation reaction to obtain porous organic polymer template materials (POFs); in the porous organic polymer template material The pores are filled with PdCu alloy nanoparticles and cerium salt precursor, and the template agent is removed by roasting to obtain a mesoporous cerium oxide supported PdCu nanoparticle catalyst.

Further, the preparation method specifically includes the following steps: weighing melamine and terephthalaldehyde and performing an aldehyde-amine polycondensation reaction to obtain a porous organic polymer template material; ultrasonically dispersing the porous organic polymer template material into palladium acetate and copper nitrate. In the mixed aqueous solution, dropwise add sodium borohydride solution to reduce the PdCu-POFs material of PdCu bimetallic nanoparticles; ultrasonically disperse the PdCu-POFs material into the cerium nitrate aqueous solution, slowly add NaOH solution dropwise under vigorous stirring, react for 3 hours, and pump. The solvent is filtered off, and the solid sample obtained is dried, placed in a muffle furnace, first heated to 600°C for 2 hours in an argon atmosphere at a rate of 4°C/min, and then roasted at 600°C in the air for 2 hours. Lower the temperature to 400°C and reduce with H ₂ /Ar for 2 hours to prepare the PdCu-CeO ₂ catalyst.

Furthermore, the preparation method of the porous organic polymer template material is as follows: adding 5g melamine (99%) and 8g terephthalaldehyde (99%) into 250mL dimethyl sulfoxide (99.9%) in an argon atmosphere. , heat to 180°C at a rate of 20°C/min, and stir the reaction at this temperature for 72h, then filter to remove the solvent and wash the yellow solid sample with ethanol three times, and vacuum dry at 80°C for 6h to prepare porous organic polymer POFs materials.

Furthermore, the mass ratio of the PdCu-POFs material to cerium nitrate is 1:2.6. The aqueous solution of cerium nitrate is prepared by dissolving 2.6 g of cerium nitrate in 50 mL of water.

Technical solution three: a method for preparing enol, using acetylenic alcohol as raw material, using the mesoporous cerium oxide supported PdCu nanoparticle catalyst as the catalyst, using ethanol as the solvent, and performing a catalytic reaction under a hydrogen atmosphere at normal pressure and room temperature. Enol is obtained. The catalytically active sites of the catalyst in the catalytic hydrogenation reaction are PdCu alloy nanoparticles. Cu regulates the electronic properties of the active metal Pd, which can significantly improve the selectivity of the reaction product. Use gas chromatography or GC-MS to analyze and detect the conversion rate of acetylenic alcohols and the selectivity of enols. The conversion rate of acetylenic alcohols can be as high as 100%, and the selectivity of enols is higher than 99%. The catalyst can at least be stably applied (recycled). )5 times.

Further, the dosage ratio of the acetylenic alcohol and the mesoporous cerium oxide supported PdCu nanoparticle catalyst is 1 mmol:10 mg. The hydrogen pressure is 1 atm.

Technical solution four: an enol prepared by the above preparation method.

Compared with the existing technology, the present invention has the following advantages and technical effects:

1. The PdCu-CeO ₂ catalyst prepared by the present invention uses the POFs template sacrificial method to make the catalyst have a high specific surface area and a larger pore size distribution; Cu metal is used as the second metal to adjust the electronic structure and active sites of the active metal Pd The composition of dots thereby improves the selectivity of hydrogenation of acetylenic alcohols to enols.

2. Using acetylenic alcohol as raw material and hydrogen as reducing agent, enol is synthesized through selective catalytic hydrogenation over PdCu-CeO ₂ catalyst at room temperature and pressure. The reaction temperature is room temperature. There is no toxic and hazardous waste emissions during the reaction process. This selective catalytic hydrogenation The method of hydrogen synthesis of acetylenic alcohols is more environmentally friendly.

3. The mesoporous PdCu-CeO ₂ catalyst provided in the present invention and its method for catalyzing the selective catalytic hydrogenation of acetylenic alcohols to synthesize enols are simple to operate, easy to control, have high product selectivity, are green and economical, and are easy to scale up industrial production.

Description of the drawings

The drawings that form a part of this application are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an improper limitation of this application. In the attached picture:

Figure 1 is a transmission electron microscope image of the PdCu-CeO ₂ catalyst prepared in Example 1 of the present invention; wherein: (a) and (b) are transmission electron microscope images at different magnifications, and (c) is the dark field transmission of the PdCu-CeO ₂ catalyst Electron micrograph;

Figure 2 is a diagram of nitrogen adsorption and desorption and pore size distribution of the PdCu-CeO ₂ catalyst prepared in Example 1 of the present invention;

Figure 3 is a diagram showing the reuse effect of the PdCu-CeO ₂ catalyst prepared in Example 3 of the present invention.

Detailed ways

Various exemplary embodiments of the invention will now be described in detail. This detailed description should not be construed as limitations of the invention, but rather as a more detailed description of certain aspects, features and embodiments of the invention.

It should be understood that the terms used in the present invention are only used to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges in the present invention, it should be understood that every intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or value intermediate within a stated range and any other stated value or value intermediate within a stated range is also included within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded from the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only the preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and/or materials in connection with which the documents relate. In the event of conflict with any incorporated document, the contents of this specification shall prevail.

It will be apparent to those skilled in the art that various modifications and changes can be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to the skilled person from the description of the invention. The specification and examples are intended to be illustrative only.

The words "includes", "includes", "has", "contains", etc. used in this article are all open terms, which mean including but not limited to.

The "room temperature" mentioned in the present invention is calculated as 20°C unless otherwise specified.

The raw materials used in the following examples of the present invention are all commercially available.

The invention provides a method for preparing a mesoporous cerium oxide-loaded PdCu nanoparticle catalyst, which mainly utilizes melamine and terephthalaldehyde to perform an aldehyde-amine polycondensation reaction to obtain porous organic polymer template materials (POFs); in the porous organic polymer template The pores of the material are filled with PdCu alloy nanoparticles and cerium salt precursors, and are calcined to remove the POFs template and reduced to obtain a PdCu-CeO ₂ catalyst in which PdCu nanoparticles are anchored in mesoporous cerium oxide pores.

The preparation method of the porous organic polymer template material is as follows: adding 5g melamine (99% active ingredient) and 8g terephthalaldehyde (99% active ingredient) into 250mL dimethyl sulfoxide (99.9% active ingredient) In an argon atmosphere, heat to 180°C at a rate of 20°C/min, and stir the reaction at this temperature for 72h. Then filter out the solvent and wash the yellow solid sample with ethanol three times, and dry it under vacuum at 80°C for 6h, that is Preparation of porous organic polymer POFs materials.

The preparation method of the PdCu-CeO ₂ catalyst is: ultrasonically disperse 1 g of POFs material in a mixed aqueous solution of palladium acetate and copper nitrate, and reduce it by dropping a dilute solution of sodium borohydride to obtain a PdCu-POFs material of PdCu bimetallic nanoparticles; Dissolve 2.6g Ce(NO ₃ ) ₃ ·6H ₂ O in 50mL water, then add 1g PdCu-POFs to the solution, sonicate the mixture for 60 minutes, then slowly add NaOH solution dropwise under vigorous stirring, and react for 3h. , filter to remove the solvent, and after drying the obtained solid sample, place it in a muffle furnace and first heat it to 600°C for 2 hours in an argon atmosphere at a rate of 4°C/min, and then bake it in the air at 600°C for 2 hours. The temperature was lowered to 400°C and reduced with a H ₂ /Ar gas mixture with a volume ratio of 1:3 for 2 hours to obtain a PdCu-CeO ₂ catalyst.

The prepared PdCu-CeO ₂ catalyst has a specific surface area of 68 m ² /g, a pore size distribution of 5-60 nm, and a pore volume of 0.3 cm ³ /g. The mass ratio of each component in the PdCu-CeO ₂ catalyst is Pd:Cu:CeO ₂ =(1-4):(1-4):100. Preferably it is 2:2:100.

The prepared PdCu-CeO ₂ catalyst, acetylenic alcohol, and solvent ethanol are added to the reactor, normal pressure hydrogen is provided as a hydrogen source, and the reaction is catalyzed at room temperature to obtain enol. During the reaction process of the selective catalytic hydrogenation of acetylenic alcohols to synthesize enols, the hydrogen pressure is 1 atm and the reaction temperature is room temperature. Use gas chromatography or GC-MS to analyze and detect the conversion rate of acetylenic alcohols and the selectivity of enols. The conversion rate of acetylenic alcohols can be as high as 100%, and the selectivity of enols is higher than 99%. The catalyst can be stably recycled at least 5 times. . The catalytic active sites of this catalytic hydrogenation reaction are PdCu alloy nanoparticles. Cu regulates the electronic properties of the active metal Pd, which can significantly improve the selectivity of the reaction products.

The following examples serve as further explanations of the technical solutions of the present invention.

Example 1

Preparation of a mesoporous cerium oxide supported PdCu nanoparticle catalyst:

1) Preparation of POFs template material: Add 5g melamine (99%) and 8g terephthalaldehyde (99%) into 250mL dimethyl sulfoxide (99.9%) in an argon atmosphere at a rate of 20°C/min. Heat to 180°C, stir the reaction at this temperature for 72 hours, then filter to remove the solvent, wash the yellow solid sample three times with ethanol, and vacuum dry at 80°C for 6 hours to prepare a porous organic polymer POFs material.

2) Preparation of PdCu- _CeO2 catalyst: 1g of POFs material was ultrasonically dispersed in 10 mL of a mixed aqueous solution of palladium acetate and copper nitrate (the mass ratio of palladium acetate, copper nitrate and water is 0.002:0.002:1), and added dropwise 2mL, 0.1mol/L concentration sodium borohydride dilute solution was reduced to obtain 1g of PdCu-POFs material of PdCu bimetallic nanoparticles; 2.6g of Ce(NO ₃ ) ₃ ·6H ₂ O was dissolved in 50mL of water, and then added to the solution Add 1g of PdCu-POFs, sonicate the mixture for 60 minutes, then slowly add 10 mL of 2 mol/L NaOH solution dropwise under vigorous stirring, react for 3 hours, filter to remove the solvent, dry and dry under an argon atmosphere at 4 The temperature was raised to 600°C and roasted for 2 hours at a rate of ℃/min, then roasted at 600°C in the air for 2 hours, and then cooled to 400°C and reduced with H ₂ /Ar (volume ratio 1:3) for 2 hours to prepare each group. 1 g of PdCu-CeO ₂ catalyst with a mass ratio of Pd:Cu:CeO ₂ =2:2:100.

Figure 1 is a transmission electron microscope image of the PdCu-CeO ₂ catalyst prepared in Example 1 of the present invention; wherein: (a) and (b) are transmission electron microscope images at different magnifications, and (c) is the dark field transmission of the PdCu-CeO ₂ catalyst Electron microscope picture; it can be seen from the picture that Pd and Cu elements are evenly distributed on the CeO ₂ carrier.

Figure 2 shows the nitrogen adsorption and desorption and pore size distribution diagram of the PdCu-CeO ₂ catalyst prepared in Example 1 of the present invention; it can be seen from the figure that the specific surface area of the prepared PdCu-CeO ₂ catalyst is 68m ² /g, and the pore size The distribution is 5-60nm, and the pore volume is 0.3cm ³ /g.

Example 2

Method for catalyzing the selective hydrogenation of acetylenic alcohols to prepare enols: Add 10 mg of the PdCu-CeO ₂ catalyst prepared in Example 1 and 1 mmol of ethoxypropynyl alcohol into a 10 mL round-bottomed flask containing 5 mL of absolute ethanol, and pass in The reaction was stirred at normal pressure with hydrogen at 70°C, and the product yield was detected by gas chromatography analysis. After 60 minutes of reaction, the conversion rate of ethoxypropynol was 94%, and the selectivity of the product ethoxypropynol was 98%.

Example 3

The PdCu-CeO ₂ catalyst after filtration, separation and recovery in Example 2 is used to catalyze the selective hydrogenation of acetylenic alcohols to prepare enols again. The specific method is as follows:

Add the recovered PdCu-CeO ₂ catalyst and 1 mmol of ethoxypropynyl alcohol into a 10 mL round-bottomed flask containing 5 mL of ethanol, add normal pressure hydrogen, stir the reaction at 70°C, and use gas chromatography to detect the product yield. The PdCu-CeO ₂ catalyst was used five times (each reaction time was 60 minutes), the conversion rates of ethoxypropynol were all higher than 90%, and the selectivity of ethoxypropynol was higher than 95% (see Figure 3).

Example 4-11

The PdCu-CeO ₂ catalyst prepared in Example 1 is used to catalyze the selective catalytic hydrogenation reaction of various types of acetylenic alcohols. The specific method is as follows:

Add 10 mg of PdCu-CeO ₂ catalyst and 1 mmol of acetylenic alcohol into a 10 mL round-bottomed flask containing 5 mL of ethanol, add normal pressure hydrogen, stir the reaction at 70°C, and use gas chromatography to analyze the product yield and specific reaction results. See Table 1.

Table 1 PdCu-CeO ₂ catalyzes the selective hydrogenation reaction of different substituted acetylenic alcohols.

The PdCu-CeO ₂ catalyst prepared in this example catalyzed the selective catalytic hydrogenation reaction of acetylenic alcohols. The specific method was the same as in Example 2. It was found that the reaction conversion rate was higher than 98% and the product selectivity was 90%.

Example 12

Same as Example 1, except that 1.7g Ce(NO ₃ ) ₃ ·6H ₂ O was dissolved in 50 mL of water, and then 0.5 g of PdCu-POFs prepared in Example 1 was added to the solution to obtain a PdCu-CeO ₂ catalyst (each The mass ratio of the components is Pd:Cu:CeO ₂ =1:1:100).

The PdCu-CeO ₂ catalyst prepared in this example catalyzed the selective catalytic hydrogenation of ethoxypropynol to synthesize ethoxypropynol. The specific method was the same as in Example 2. It was found that the reaction conversion rate was 86%, and the product selectivity was 98%.

Example 13

Same as Example 1, except that 1.7g Ce(NO ₃ ) ₃ ·6H ₂ O was dissolved in 50 mL of water, and then 1.5g of PdCu-POFs prepared in Example 1 was added to the solution to obtain a PdCu-CeO ₂ catalyst (each The mass ratio of the components is Pd:Cu:CeO ₂ =3:3:100).

The PdCu-CeO ₂ catalyst prepared in this example catalyzed the selective catalytic hydrogenation of ethoxypropynol to synthesize ethoxypropynol. The specific method was the same as in Example 2. It was found that the reaction conversion rate was 99% and the product selectivity was 92%.

Example 14

Same as Example 1, except that 1.7g Ce(NO ₃ ) ₃ ·6H ₂ O was dissolved in 50 mL of water, and then 2g of PdCu-POFs prepared in Example 1 was added to the solution to obtain a PdCu-CeO ₂ catalyst (each component The mass ratio is Pd:Cu:CeO ₂ =4:4:100).

The PdCu-CeO ₂ catalyst prepared in this example catalyzed the selective catalytic hydrogenation of ethoxypropynol to synthesize ethoxypropynol. The specific method was the same as in Example 2. It was found that the reaction conversion rate was 100% and the product selectivity was 87%.

Comparative example 1

Same as Example 1, except that the same amount of palladium acetate is replaced by platinum acetate.

The catalyst prepared in this comparative example was used to catalyze the selective catalytic hydrogenation reaction of acetylenic alcohols. The specific method was the same as in Example 2. It was found that the reaction conversion rate was higher than 85% and the product selectivity was 95%.

Comparative example 2

Same as Example 2, except that the same amount of copper nitrate is replaced by palladium acetate.

The palladium-supported catalyst prepared in this comparative example was used to catalyze the selective catalytic hydrogenation reaction of acetylenic alcohols. The specific method was the same as in Example 2. It was found that the reaction conversion rate was higher than 99% and the product selectivity was 84%.

Comparative example 3

Same as Example 2, except that the added amount of PdCu-CeO ₂ catalyst is 8 mg.

The PdCu- _CeO2 catalyst prepared in this comparative example was used to catalyze the selective catalytic hydrogenation reaction of acetylenic alcohols. It was found that the reaction conversion rate was higher than 86% and the product selectivity was 98%.

The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any person familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application. All are covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims (10)

1. A mesoporous cerium oxide supported PdCu nanoparticle catalyst, characterized in that the mass ratio of each component in the mesoporous cerium oxide supported PdCu nanoparticle catalyst is Pd:Cu:CeO ₂ =(1-4): (1-4):100. 2. The mesoporous cerium oxide-loaded PdCu nanoparticle catalyst according to claim 1, characterized in that the mesoporous cerium oxide-loaded PdCu nanoparticle catalyst has a specific surface area of ^68m2 /g and a pore size distribution of 5-60nm, The pore volume is 0.3cm ³ /g. 3. A method for preparing a mesoporous cerium oxide-loaded PdCu nanoparticle catalyst as claimed in claim 1 or 2, characterized in that melamine and terephthalaldehyde are used to carry out an aldehyde-amine polycondensation reaction to obtain a porous organic polymer template material. ; Filling the pores of the porous organic polymer template material with PdCu alloy nanoparticles and cerium salt precursor; roasting to remove the template agent to obtain a mesoporous cerium oxide supported PdCu nanoparticle catalyst. 4. The preparation method of mesoporous cerium oxide-loaded PdCu nanoparticle catalyst according to claim 3, characterized in that the method of filling PdCu alloy nanoparticles and cerium salt precursor specifically includes the following steps: The porous organic polymer template material is ultrasonically dispersed in a mixed aqueous solution of palladium acetate and copper nitrate, and reduced by adding sodium borohydride solution dropwise to obtain a PdCu-POFs material of PdCu bimetallic nanoparticles; The PdCu-POFs material was ultrasonically dispersed into the aqueous solution of cerium nitrate, the NaOH solution was added dropwise under stirring, the reaction was carried out for 3 hours, the solvent was removed by suction filtration, and the resulting solid sample was dried. 5. The preparation method of the mesoporous cerium oxide-loaded PdCu nanoparticle catalyst according to claim 3, characterized in that the roasting method is as follows: successively heating to 600°C in argon and air atmospheres and roasting for 2 hours each, Then the temperature was lowered to 400°C and reduced with H ₂ /Ar. 6. The preparation method of mesoporous cerium oxide supported PdCu nanoparticle catalyst according to claim 3, characterized in that the mass ratio of melamine and terephthalaldehyde is 5:8. 7. The preparation method of mesoporous cerium oxide supported PdCu nanoparticle catalyst according to claim 4, characterized in that the mass ratio of the PdCu-POFs material and cerium nitrate is 1:2.6. 8. A preparation method of enol, characterized in that, using acetylenic alcohol as raw material, using the mesoporous cerium oxide supported PdCu nanoparticle catalyst as claimed in claim 1 or 2 as the catalyst, ethanol as the solvent, at normal pressure and room temperature. The catalytic reaction is carried out under a hydrogen atmosphere to obtain enol. 9. The preparation method according to claim 8, characterized in that the dosage ratio of the acetylenic alcohol and the mesoporous cerium oxide supported PdCu nanoparticle catalyst is 1 mmol:10 mg. 10. An enol prepared by the preparation method according to claim 8 or 9.