Preparation method and application of Cu-based catalyst for acetalation reaction

Abstract

The invention provides a preparation method of a Cu-based catalyst for acetalation reaction, which comprises the following steps: depositing Pt on the surface of a pretreated carbon carrier through an atomic layer deposition method, depositing a metal oxide CuOx on the surface of the metal Pt, and performing high-temperature reduction and medium-temperature oxidation treatment to obtain the Cu-based catalyst. According to the method, the size of Pt particles and the thickness of CuOx can be accurately controlled on the atomic scale. The catalyst is applied to the acetalation reaction of aldol, the size of Pt particles and the thickness of CuOx can be accurately controlled on the atomic scale in the hydrogen atmosphere, the Pt-coated CuOx core-shell structure catalyst with cuprous as the main component is obtained on the surface of the carbon carrier, and the catalyst has the catalytic performance of high acetal yield due to the stable cuprous structure. The preparation of the catalyst is simple and controllable, and the greenization of the aldol acetalation reaction process and the high efficiency of the product are realized through the catalyst.

Description

Technical Field

[0001] The invention belongs to the technical field of Cu-based catalysts, and particularly relates to a preparation method and application of a Cu-based catalyst for acetalization reaction. Background Art

[0002] Due to their unique chemical structure, acetal compounds are considered to be a stable intermediate product. They play an important role in the protection of aldehyde carbonyl and ketone carbonyl groups and can be used in processes such as the synthesis of lipids, sugars, steroids and complex natural products. At the same time, due to the special smell of acetal compounds, they are widely used in food additives, dyes, cosmetics, pharmaceutical industry and other fields. According to the nature of the functional group and the size of the molecule, acetal compounds can be added as additives to lubricating oil to improve its antioxidant capacity, and can also be added to diesel fuel to play an antifreeze role.

[0003] In traditional industrial production, this type of compound is mainly formed by the acetalization reaction of the corresponding alcohol and aldehyde under the catalytic action of strong acid. Although this process has a simple production process, high conversion rate and selectivity, the catalyst is highly acidic, which requires the equipment to have high corrosion resistance. And because it is a homogeneous catalyst, it often leads to the load of subsequent product separation and increases the risk of environmental pollution. In order to effectively solve these problems, solid acid catalysts or ionic liquid catalysts have been gradually replaced by ionic acid catalysts in recent years. However, the preparation process of this type of catalyst and the treatment process after the reaction are still cumbersome, so it is very necessary to develop a simple, efficient and green heterogeneous catalyst.

[0004] Cu-based catalysts, especially those with monovalent Cu as the active component, have shown excellent performance in the synthesis or conversion of alcohols or aldehydes. However, due to the instability of monovalent Cu, it is easily oxidized to divalent copper or reduced to metallic copper during the reaction. Therefore, how to obtain stable monovalent copper during the reaction and maintain the high activity and selectivity of the catalyst has always been a technical difficulty for Cu-based catalysts. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a preparation method and application of a Cu-based catalyst for acetalization reaction in view of the above-mentioned deficiencies in the prior art, wherein the active phase in the Cu-based catalyst is mainly monovalent Cu, thereby maintaining the high catalytic performance of the Cu-based catalyst.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a Cu-based catalyst for acetalization reaction, the method comprising:

[0007] S1, pretreating the carbon carrier to obtain a pretreated carbon carrier;

[0008] S2. The pretreated carbon carrier obtained in S1 is subjected to Pt deposition in an atomic layer deposition system, specifically: firstly, a vapor pulse of a Pt metal precursor is introduced into the deposition chamber, with a pulse time of 1 s, a breath holding time of 10 s, and a nitrogen purge time of 25 s; then, an ozone or oxygen pulse with a flow rate of 50 sccm is introduced into the reaction chamber, with a pulse time of 0.1 s, a breath holding time of 12 s, and a nitrogen purge time of 30 s, thus completing one Pt deposition cycle, and repeating the Pt deposition cycle 10 times to obtain a carbon carrier with Pt nanoparticles deposited on the surface, recorded as Pt / C;

[0009] S3, the Pt / C obtained in S2 is subjected to Cu deposition in an atomic layer deposition system, specifically: firstly, the vapor pulse of Cu metal precursor is introduced into the reaction chamber, the pulse time is 5s, the breath holding time is 10s, and the nitrogen purge time is 25s; then, ozone or oxygen pulse is introduced into the reaction chamber, the pulse time is 0.2s, the breath holding time is 12s, and the nitrogen purge time is 30s, thus completing one Cu deposition cycle, and repeating the Cu deposition cycle 50 to 200 times to obtain a carbon carrier with Pt@CuO deposited on the surface, recorded as Pt@CuO / C;

[0010] S4. After heat treatment of the Pt@CuO / C obtained in S3, the Cu-based catalyst for acetalization reaction is obtained after natural cooling to room temperature, which is recorded as Pt@CuO x / C catalyst, 0.3<x<0.6; the heat treatment method is: reducing at 300℃ for 2h under a reducing atmosphere, then cooling to 80℃ at a cooling rate of 10℃ / min, and introducing air atmosphere for constant temperature treatment for 30min.

[0011] Preferably, the pretreatment method of the carbon carrier in S1 is: dispersing the carbon carrier in ethanol to obtain a suspension, and evaporating the suspension to obtain a pretreated carbon carrier.

[0012] Preferably, the carbon carrier is a carbon nanotube. The carbon carrier in the present invention may also be carbon nanofibers, graphite, graphene and carbon microspheres.

[0013] Preferably, the Pt metal precursor in S2 is trimethylmethylcyclopentadienylplatinum; the parameters of the Pt deposition are: the reaction temperature is 220°C, the temperature of the trimethylmethylcyclopentadienylplatinum is 70°C, the ozone or oxygen temperature is 30°C, and the nitrogen flow rate is 50sccm.

[0014] Preferably, the Cu metal precursor in S2 is di(hexafluoropentanedione)copper; the parameters of the Cu deposition are: the reaction temperature is 220°C, the temperature of the di(hexafluoropentanedione)copper is 80°C, the temperature of water is 30°C, and the nitrogen flow rate is 50sccm.

[0015] Preferably, the reducing atmosphere in S4 is a 10% H2 / Ar mixed gas with a flow rate of 50 sccm; and the flow rate of the air atmosphere is 50 sccm.

[0016] The present invention also provides the use of a Cu-based catalyst for acetalization reaction prepared by the above-mentioned preparation method, wherein the Cu-based catalyst is used for acetalization reaction under a hydrogen atmosphere.

[0017] Preferably, the acetalization reaction comprises the reaction of ethanol and cinnamaldehyde to generate cinnamaldehyde diethyl acetal, the reaction of ethanol and benzaldehyde to generate benzaldehyde diethyl acetal, the reaction of methanol and benzaldehyde to generate benzaldehyde dimethyl acetal, and the reaction of ethylene glycol and benzaldehyde to generate benzaldehyde ethylene glycol acetal.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] The present invention uses an atomic layer deposition method to first deposit metal Pt on the surface of a pretreated carbon carrier, and then deposit metal oxide CuO x The Pt@CuO nanostructured carbon was deposited on the surface of the metal Pt and then subjected to high-temperature reduction and medium-temperature oxidation treatment to obtain Pt@CuO nanostructured carbon. x Core-shell structure catalyst. The present invention can precisely control the size of Pt particles and CuO at the atomic scale. x The catalyst is applied to the acetalization reaction of alcohol-aldehyde. Under a hydrogen atmosphere, the present invention can stabilize the Cu on the catalyst surface in a monovalent state, so that the catalyst exhibits a catalytic performance with a high acetal yield. The preparation of the catalyst in the present invention is simple and controllable, and the greening of the alcohol-aldehyde acetalization reaction process and the high efficiency of the product are achieved through the catalyst.

[0020] The present invention is further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a transmission electron micrograph of the Cu-based catalyst for acetalization reaction prepared in Example 1 of the present invention.

[0022] Figure 2 This is an XPS data chart of the Cu-based catalyst for acetalization reaction prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0023] Example 1

[0024] The preparation method of the Cu-based catalyst for acetalization reaction of the present embodiment is as follows:

[0025] S1. Pretreating the carbon carrier, the pretreatment method is: dispersing carbon nanotubes (CNTs) of the carbon carrier in ethanol to obtain a suspension with a concentration of 0.05 g / mL, taking 1 mL of the suspension and coating it on the surface of a glass sheet, and evaporating it to obtain a pretreated carbon carrier;

[0026] S2. The pretreated carbon carrier obtained in S1 is subjected to Pt deposition in an atomic layer deposition system. The pressure of the atomic layer deposition chamber is 70 Pa. The parameters of the Pt deposition are set as follows: the reaction temperature is 220°C, the temperature of the Pt metal precursor trimethyl methylcyclopentadienyl platinum is 70°C, the ozone temperature is 30°C, and the nitrogen flow rate is 50 sccm; first, a vapor pulse of trimethyl methylcyclopentadienyl platinum is introduced into the deposition chamber, the pulse time is 1 s, the breath holding time is 10 s, and the nitrogen purge time is 25 s; then, an ozone pulse with a flow rate of 50 sccm is introduced into the reaction chamber, the pulse time is 0.1 s, the breath holding time is 12 s, and the nitrogen purge time is 30 s. Thus, one Pt deposition cycle is completed. The Pt deposition cycle is repeated 10 times to obtain a carbon carrier with Pt nanoparticles deposited on the surface, which is recorded as Pt / C;

[0027] S3, the Pt / C obtained in S2 is subjected to Cu deposition in an atomic layer deposition system, and the parameters of Cu deposition are set as follows: reaction temperature is 220°C, temperature of Cu metal precursor di(hexafluoropentanedione)copper is 80°C, temperature of ozone is 30°C, and nitrogen flow rate is 50sccm; firstly, vapor pulse of di(hexafluoropentanedione)copper is introduced into the reaction chamber, with a pulse time of 5s, a breath holding time of 10s, and a nitrogen purge time of 25s; then, ozone pulse is introduced into the reaction chamber, with a pulse time of 0.2s, a breath holding time of 12s, and a nitrogen purge time of 30s, thus completing one Cu deposition cycle, and repeating the Cu deposition cycle 150 times to obtain a carbon carrier with Pt@CuO deposited on the surface, recorded as Pt@150CuO / C;

[0028] S4, heat-treating the Pt@150CuO / C obtained in S3, and then cooling it to room temperature to obtain a Cu-based catalyst for acetalization reaction, denoted as Pt@150CuO x / C catalyst, CuO x It indicates that monovalent copper, zero-valent copper and divalent copper coexist, and the CuO part is mainly converted into monovalent copper after heat treatment; the heat treatment method is: introducing a reducing atmosphere 10% H2 / Ar mixed gas with a flow rate of 50sccm, reducing at a temperature of 300°C for 2h, then cooling to 80°C at a cooling rate of 10°C / min, and introducing an air atmosphere with a flow rate of 50sccm for constant temperature treatment for 30min.

[0029] Figure 1 This is a transmission electron microscope photo of the obtained Cu-based catalyst. Figure 1It can be seen that Pt is deposited on the surface of carbon nanotubes, and its particle size is about 1.2nm. x It is mainly deposited on the surface of Pt, thus forming a Pt@CuO with a core-shell structure. x Catalyst, CuO under 150 cycles of deposition conditions x The thickness is about 1.5nm. Figure 1 It is fully demonstrated that the method of the present invention can successfully prepare Pt@CuO with a core-shell structure. x / C catalyst.

[0030] Figure 2 Pt@150CuO prepared in this example x / C catalyst Cu 2p XPS results, by Figure 2 It can be seen that no obvious oscillation peak is observed at 940-945 eV, and the peak at 932.2 eV mainly points to monovalent copper. x The Cu in the / C catalyst is mainly in the monovalent state, and CuO x The value range of X is: 0.3<x<0.6.

[0031] This embodiment can control the Pt and CuO x The deposition cycles are very accurate, and the size of Pt particles and CuO are precisely controlled at the atomic scale. x Thickness.

[0032] During the heat treatment of S4, due to the x / C catalyst is based on Pt as the core, CuO x The core-shell catalyst is a core-shell catalyst with a core-shell structure. At lower temperatures, the activation site of hydrogen is mainly on the Pt site. Therefore, under a certain hydrogen atmosphere, CuO x The shell structure of CuO can control the activation degree of hydrogen by diffusion, thus achieving x During the reaction, the dynamic balance between oxidation and reduction makes CuO x The Cu in the ion always remains in a monovalent state.

[0033] This embodiment also provides the application of the prepared Cu-based catalyst, wherein the Cu-based catalyst is used for acetalization reaction.

[0034] (1) Ethanol and cinnamaldehyde react to form cinnamaldehyde diethyl acetal: the reaction apparatus is a 50 mL tank reactor; Pt@150CuO xThe amount of / C catalyst was 15 mg, the amount of ethanol was 15 mL, and the amount of substrate cinnamaldehyde was 2.1 mL; the stirring speed was 2500 r / min, the reaction temperature was 60°C, the H2 pressure was 0.2 MPa, and the reaction time was 1 h. The results of gas chromatography online analysis showed that the conversion rate of cinnamaldehyde was 88.5%, and the selectivity of cinnamaldehyde diethyl acetal was 97.1%.

[0035] (2) Ethanol and benzaldehyde react to form benzaldehyde diethyl acetal: the reaction apparatus is a 50 mL tank reactor; Pt@150CuO x The dosage of / C catalyst was 15 mg, the dosage of ethanol was 15 mL, the dosage of substrate benzaldehyde was 1.8 mL; the stirring speed was 2500 r / min, the reaction temperature was 60°C, the H2 pressure was 0.2 MPa, and the reaction time was 2 h. The results of gas chromatography online analysis showed that the conversion rate of benzaldehyde was 86.3%, and the selectivity of benzaldehyde diethyl acetal was 95.5%.

[0036] (3) Methanol and benzaldehyde react to form benzaldehyde dimethyl acetal: the reaction apparatus is a 50 mL tank reactor; Pt@150CuO x The dosage of / C catalyst was 15 mg, the dosage of methanol was 15 mL, the dosage of substrate benzaldehyde was 2.5 mL; the stirring speed was 2500 r / min, the reaction temperature was 55°C, the H2 pressure was 0.2 MPa, and the reaction time was 1 h. The results of gas chromatography online analysis showed that the conversion rate of benzaldehyde was 87.5%, and the selectivity of benzaldehyde dimethyl acetal was 94.6%.

[0037] (4) Ethylene glycol and benzaldehyde react to form benzaldehyde ethylene glycol acetal: the reaction apparatus is a 50 mL autoclave reactor; Pt@150CuO x The dosage of / C catalyst was 15 mg, the dosage of ethylene glycol was 15 mL, the dosage of substrate benzaldehyde was 1.8 mL; the stirring speed was 3000 r / min, the reaction temperature was 80°C, the H2 pressure was 0.2 MPa, and the reaction time was 1.5 h. The results of gas chromatography online analysis showed that the conversion rate of benzaldehyde was 84.2%, and the selectivity of benzaldehyde ethylene glycol acetal was 93.1%.

[0038] The catalyst was applied to the acetalization reaction of alcohol-aldehyde. In a hydrogen atmosphere, the present embodiment was able to stabilize the CuO in the catalyst. x The monovalent state is dominant, and due to the monovalent CuO x The oxygen vacancies in the catalyst can effectively promote the adsorption of the reaction substrate, so that the catalyst exhibits a catalytic performance with a high acetal yield. The preparation of the catalyst in this embodiment is simple and controllable, and the catalyst realizes the greening of the aldol acetalization reaction process and the high efficiency of the product.

[0039] Comparative Example 1

[0040] This comparative example is a method for preparing a 20Pt / C catalyst, which is as follows: steps S1-S2 are the same as those in Example 1, and the carbon carrier (Pt / C) with surface-deposited Pt nanoparticles prepared in S2 is heat-treated and then naturally cooled to room temperature to obtain a 20Pt / C catalyst; the heat treatment method is as follows: a reducing atmosphere of 10% H2 / Ar mixed gas with a flow rate of 50sccm is introduced, and the mixture is reduced at a temperature of 300°C for 2h, and then the mixture is cooled to 80°C at a cooling rate of 10°C / min, and an air atmosphere with a flow rate of 50sccm is introduced for constant temperature treatment for 30min.

[0041] The 20Pt / C catalyst prepared in this comparative example is used for acetalization reaction, and ethanol and cinnamaldehyde react to generate cinnamaldehyde diethyl acetal: the reaction device is a 50mL autoclave reactor; the amount of 20Pt / C catalyst is 15mg, the amount of ethanol is 15mL, and the amount of substrate cinnamaldehyde is 2.1mL; the stirring speed is 2500r / min, the reaction temperature is 60℃, the H2 pressure is 0.2MPa, and the reaction time is 2h. Gas chromatography online analysis results: the conversion rate of cinnamaldehyde is 82.3%, and the selectivity of cinnamaldehyde diethyl acetal is 36.2%.

[0042] Comparative Example 2

[0043] This comparative example is 150CuO x / C catalyst preparation method, the method is:

[0044] Step S1 is the same as S1 in Example 1;

[0045] S2. The pretreated carbon carrier obtained in S1 is subjected to Cu deposition in an atomic layer deposition system. The pressure of the atomic layer deposition chamber is 70 Pa. The parameters of the Cu deposition are set as follows: the reaction temperature is 220° C., the temperature of the Cu metal precursor di(hexafluoropentanedione)copper is 80° C., the temperature of the ozone is 30° C., and the nitrogen flow rate is 50 sccm. First, the vapor pulse of di(hexafluoropentanedione)copper is introduced into the reaction chamber, the pulse time is 5 s, the breath holding time is 10 s, and the nitrogen purge time is 25 s. Then, the ozone pulse is introduced into the reaction chamber, the pulse time is 0.2 s, the breath holding time is 12 s, and the nitrogen purge time is 30 s. This completes one Cu deposition cycle. The Cu deposition cycle is repeated 150 times to obtain 150CuO / C.

[0046] S4, heat-treating the 150CuO / C obtained in S3, and then naturally cooling it to room temperature to obtain 150CuO x / C catalyst; the heat treatment method is: introducing a reducing atmosphere of 10% H2 / Ar mixed gas with a flow rate of 50sccm, reducing at a temperature of 300°C for 2h, then cooling to 80°C at a cooling rate of 10°C / min, and introducing an air atmosphere with a flow rate of 50sccm for constant temperature treatment for 30min.

[0047] In this comparative example, 150 CuO x / C catalyst is used for acetalization reaction, ethanol and cinnamaldehyde react to generate cinnamaldehyde diethyl acetal: the reaction device is a 50mL autoclave reactor; the amount of 20Pt / C catalyst is 15mg, the amount of ethanol is 15mL, and the amount of substrate cinnamaldehyde is 2.1mL; the stirring speed is 2500r / min, the reaction temperature is 60℃, the H2 pressure is 0.2MPa, and the reaction time is 2h. The results of gas chromatography online analysis show that the conversion rate of cinnamaldehyde is 21.5%, and the selectivity of cinnamaldehyde diethyl acetal is 92.7%.

[0048] Comparative Example 3

[0049] The preparation method of the Cu-based catalyst for acetalization reaction in this comparative example is the same as that in Example 1, and Pt@150CuO is prepared. x / C catalyst.

[0050] The difference is that the reaction conditions when the catalyst is used to catalyze the acetalization reaction of ethanol and cinnamaldehyde to generate cinnamaldehyde diethyl acetal are different.

[0051] The reaction device is a 50mL kettle reactor; Pt@150CuO x The dosage of / C catalyst was 15 mg, the dosage of ethanol was 15 mL, the dosage of substrate cinnamaldehyde was 2.1 mL; the stirring speed was 2500 r / min, the reaction temperature was 60°C, the N2 pressure was 0.2 MPa, and the reaction time was 2 h. The results of gas chromatography online analysis showed that the conversion rate of cinnamaldehyde was 8.7%, and the selectivity of cinnamaldehyde diethyl acetal was 92.5%.

[0052] It can be seen from Example 1 and Comparative Example 1 that when the catalyst is free of Cu, in a hydrogen atmosphere, cinnamaldehyde mainly undergoes a hydrogenation process rather than an acetalization process with ethanol. x It is mainly the active site of the acetalization process. It can be seen from Example 1 and Comparative Example 2 that when the catalyst does not have Pt, cinnamaldehyde and ethanol are xAlthough the acetalization process mainly occurs under the catalysis of Pt@150CuO, its activity decreases significantly. This is mainly because in the absence of Pt, CuO is mainly converted into zero-valent copper and a small amount of monovalent copper during the heat treatment process, which leads to too little monovalent copper in the catalyst prepared in Comparative Example 2, and the subsequent acetalization reaction activity decreases significantly. Further, it can be seen from Example 1 and Comparative Example 3 that in the absence of hydrogen, Pt@150CuO x / C catalyst still showed very poor catalytic activity. Therefore, in order to ensure high activity and high selectivity of the catalyst, hydrogen must be activated by Pt to promote the valence state of Cu in the catalyst to be positive monovalent. The above comparative examples fully illustrate that Pt in the catalyst, monovalent Cu and hydrogen at a certain pressure in the acetalization reaction are indispensable.

[0053] Example 2

[0054] The preparation method of the Cu-based catalyst for acetalization reaction of the present embodiment is as follows:

[0055] S1. Pretreating the carbon carrier, the pretreatment method is: dispersing carbon nanotubes (CNTs) of the carbon carrier in ethanol to obtain a suspension with a concentration of 0.05 g / mL, taking 1 mL of the suspension and coating it on the surface of a glass sheet, and evaporating it to obtain a pretreated carbon carrier;

[0056] S2. The pretreated carbon carrier obtained in S1 is subjected to Pt deposition in an atomic layer deposition system. The pressure of the atomic layer deposition chamber is 70 Pa. The parameters of the Pt deposition are set as follows: the reaction temperature is 220°C, the temperature of the Pt metal precursor trimethyl methylcyclopentadienyl platinum is 70°C, the oxygen temperature is 30°C, and the nitrogen flow rate is 50 sccm; firstly, a vapor pulse of trimethyl methylcyclopentadienyl platinum is introduced into the deposition chamber, the pulse time is 1 s, the breath holding time is 10 s, and the nitrogen purge time is 25 s; then, an ozone pulse with a flow rate of 50 sccm is introduced into the reaction chamber, the pulse time is 0.1 s, the breath holding time is 12 s, and the nitrogen purge time is 30 s. Thus, one Pt deposition cycle is completed. The Pt deposition cycle is repeated 10 times to obtain a carbon carrier with Pt nanoparticles deposited on the surface, which is recorded as Pt / C;

[0057] S3, the Pt / C obtained in S2 is subjected to Cu deposition in an atomic layer deposition system, and the parameters of Cu deposition are set as follows: reaction temperature is 220°C, temperature of Cu metal precursor di(hexafluoropentanedione)copper is 80°C, temperature of oxygen is 30°C, and nitrogen flow rate is 50sccm; firstly, vapor pulse of di(hexafluoropentanedione)copper is introduced into the reaction chamber, with a pulse time of 5s, a breath holding time of 10s, and a nitrogen purge time of 25s; then, oxygen pulse is introduced into the reaction chamber, with a pulse time of 0.2s, a breath holding time of 12s, and a nitrogen purge time of 30s, thus completing one Cu deposition cycle, and repeating 100 Cu deposition cycles to obtain a carbon carrier with Pt@CuO deposited on the surface, recorded as Pt@100CuO / C;

[0058] S4, heat-treating the Pt@100CuO / C obtained in S3, and then naturally cooling it to room temperature to obtain a Cu-based catalyst for acetalization reaction, recorded as Pt@100CuO x / C catalyst, 0.3<x<0.6; the heat treatment method is: introducing a reducing atmosphere 10% H2 / Ar mixed gas with a flow rate of 50sccm, reducing at a temperature of 300℃ for 2h, then cooling to 80℃ at a cooling rate of 10℃ / min, and introducing an air atmosphere with a flow rate of 50sccm for constant temperature treatment for 30min.

[0059] The catalyst is used for acetalization reaction, and ethanol and cinnamaldehyde react to generate cinnamaldehyde diethyl acetal.

[0060] The reaction device is a 50mL kettle reactor; Pt@100CuO x The amount of / C catalyst was 15 mg, the amount of ethanol was 15 mL, and the amount of substrate cinnamaldehyde was 2.1 mL; the stirring speed was 2500 r / min, the reaction temperature was 60°C, the H2 pressure was 0.2 MPa, and the reaction time was 1 h. The results of gas chromatography online analysis showed that the conversion rate of cinnamaldehyde was 74.1%, and the selectivity of cinnamaldehyde diethyl acetal was 87.5%.

[0061] Example 3

[0062] The preparation method of the Cu-based catalyst for acetalization reaction in this embodiment is the same as that in Example 1, except that the Cu deposition in step S3 is cycled 50 times, and the carbon support with surface deposited Pt@CuO prepared in step S3 is recorded as Pt@50CuO / C;

[0063] The final prepared Cu-based catalyst for acetalization reaction is denoted as Pt@50CuO x / C catalyst, which is used for acetalization reaction, and ethanol and cinnamaldehyde react to generate cinnamaldehyde diethyl acetal.

[0064] The reaction device is a 50mL kettle reactor; Pt@50CuO x The amount of / C catalyst was 15 mg, the amount of ethanol was 15 mL, and the amount of substrate cinnamaldehyde was 2.1 mL; the stirring speed was 2500 r / min, the reaction temperature was 60°C, the H2 pressure was 0.2 MPa, and the reaction time was 1 h. The results of gas chromatography online analysis showed that the conversion rate of cinnamaldehyde was 68.7%, and the selectivity of cinnamaldehyde diethyl acetal was 88.2%.

[0065] Example 4

[0066] The preparation method of the Cu-based catalyst for acetalization reaction in this embodiment is the same as that in Example 1, except that the Cu deposition in step S3 is cycled 200 times, and the carbon support with surface deposited Pt@CuO prepared in step S3 is recorded as Pt@200CuO / C;

[0067] The final prepared Cu-based catalyst for acetalization reaction is denoted as Pt@200CuO x / C catalyst, 0.3<x<0.6, the catalyst is used for acetalization reaction, ethanol and cinnamaldehyde react to generate cinnamaldehyde diethyl acetal.

[0068] The reaction device is a 50mL kettle reactor; Pt@200CuO x The amount of / C catalyst was 15 mg, the amount of ethanol was 15 mL, and the amount of substrate cinnamaldehyde was 2.1 mL; the stirring speed was 2500 r / min, the reaction temperature was 60°C, the H2 pressure was 0.2 MPa, and the reaction time was 1 h. The results of gas chromatography online analysis showed that the conversion rate of cinnamaldehyde was 68.5%, and the selectivity of cinnamaldehyde diethyl acetal was 99.2%.

[0069] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a Cu-based catalyst for acetalization reaction, characterized in that: The method is: S1, pretreating the carbon carrier to obtain a pretreated carbon carrier; S2. The pretreated carbon carrier obtained in S1 is subjected to Pt deposition in an atomic layer deposition system, specifically: firstly, a vapor pulse of a Pt metal precursor is introduced into the deposition chamber, with a pulse time of 1 s, a breath holding time of 10 s, and a nitrogen purge time of 25 s; then, an ozone or oxygen pulse with a flow rate of 50 sccm is introduced into the reaction chamber, with a pulse time of 0.1 s, a breath holding time of 12 s, and a nitrogen purge time of 30 s, thus completing one Pt deposition cycle, and repeating the Pt deposition cycle 10 times to obtain a carbon carrier with Pt nanoparticles deposited on the surface, recorded as Pt / C; S3, the Pt / C obtained in S2 is subjected to Cu deposition in an atomic layer deposition system, specifically: firstly, the vapor pulse of Cu metal precursor is introduced into the reaction chamber, the pulse time is 5s, the breath holding time is 10s, and the nitrogen purge time is 25s; then, ozone or oxygen pulse is introduced into the reaction chamber, the pulse time is 0.2s, the breath holding time is 12s, and the nitrogen purge time is 30s, thus completing one Cu deposition cycle, and repeating the Cu deposition cycle 50 to 200 times to obtain a carbon carrier with Pt@CuO deposited on the surface, recorded as Pt@CuO / C; S4, heat-treating the Pt@CuO / C obtained in S3, and naturally cooling it to room temperature to obtain a Cu-based catalyst for acetalization reaction, denoted as Pt@CuO x / C catalyst, 0.3<x<0.6; the heat treatment method is: reducing at 300℃ for 2h under a reducing atmosphere, then cooling to 80℃ at a cooling rate of 10℃ / min, and introducing air atmosphere for constant temperature treatment for 30min.

2. The method for preparing a Cu-based catalyst for acetalization reaction according to claim 1, characterized in that: The pretreatment method of the carbon carrier in S1 is: dispersing the carbon carrier in ethanol to obtain a suspension, and evaporating to dryness to obtain a pretreated carbon carrier.

3. The method for preparing a Cu-based catalyst for acetalization reaction according to claim 2, characterized in that: The carbon carrier is carbon nanotube.

4. The method for preparing a Cu-based catalyst for acetalization reaction according to claim 1, characterized in that: The Pt metal precursor in S2 is trimethyl methylcyclopentadienyl platinum; the parameters of the Pt deposition are: the reaction temperature is 220°C, the temperature of the trimethyl methylcyclopentadienyl platinum is 70°C, the ozone or oxygen temperature is 30°C, and the nitrogen flow rate is 50sccm.

5. The method for preparing a Cu-based catalyst for acetalization reaction according to claim 1, characterized in that: The Cu metal precursor in S2 is di(hexafluoropentanedione)copper; the parameters of the Cu deposition are: the reaction temperature is 220°C, the temperature of the di(hexafluoropentanedione)copper is 80°C, the temperature of the ozone or oxygen is 30°C, and the nitrogen flow rate is 50sccm.

6. The method for preparing a Cu-based catalyst for acetalization reaction according to claim 1, characterized in that: The reducing atmosphere in S4 is a 10% H2 / Ar mixed gas with a flow rate of 50 sccm; the flow rate of the air atmosphere is 50 sccm.

7. Use of a Cu-based catalyst for acetalization reaction prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The Cu-based catalyst is used for acetalization reaction under hydrogen atmosphere.

8. The use according to claim 7, characterized in that: The acetalization reaction comprises the following steps: ethanol and cinnamaldehyde react to generate cinnamaldehyde diethyl acetal, ethanol and benzaldehyde react to generate benzaldehyde diethyl acetal, methanol and benzaldehyde react to generate benzaldehyde dimethyl acetal, and ethylene glycol and benzaldehyde react to generate benzaldehyde ethylene glycol acetal.

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