Preparation method of biomass-based nitrogen-carbon material supported zirconium-based catalyst and application of biomass-based nitrogen-carbon material supported zirconium-based catalyst in salicylaldehyde MPV transfer hydrogenation reaction

Abstract

The invention belongs to the technical field of MPV transfer hydrogenation catalysts, and discloses a preparation method of a biomass-based nitrogen-carbon material supported zirconium-based catalyst and application of the biomass-based nitrogen-carbon material supported zirconium-based catalyst in salicylaldehyde MPV transfer hydrogenation reaction. According to the catalyst, a biomass-based nitrogen-carbon material is used as a nitrogen source and a carbon source, zircon salt is used as a precursor, and the zirconium oxide-loaded nitrogen-carbon catalyst (ZrO2 / NC) is prepared by adopting hydrothermal carbonization and high-temperature thermal cracking methods. Wherein the nitrogen-carbon precursor is a biomass-based material, and the zircon salt is inorganic salt or organic salt. The specific surface area and the acid-base property of the catalyst can be accurately regulated and controlled by adjusting factors such as the ratio of the zirconium salt to the nitrogen-carbon precursor, the hydrothermal carbonization temperature and the roasting temperature. The preparation process of the catalyst is simple, the catalyst has good catalytic performance in MPV transfer hydrogenation reaction of salicylaldehyde compounds, salicylaldehyde reacts at 170 DEG C, the conversion rate of salicylaldehyde can reach 99.2%, and the maximum selectivity of salicylaldehyde reaches 98.1%.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical catalytic materials, and specifically relates to the preparation of a biomass-based nitrogen-carbon material-loaded zirconium-based catalyst and its application in the transfer hydrogenation reaction of salicylaldehyde MPV. Background Art

[0002] Salicyl alcohol, also known as 2-hydroxybenzyl alcohol, is an important chemical raw material that can be used to synthesize a variety of chemicals and drugs. It has a wide range of applications in the fields of medicine, spices and pesticides. A typical synthesis method of salicyl alcohol is to use phenol and formaldehyde as raw materials and zinc acetate as a catalyst to synthesize in an aqueous medium. After the reaction is completed, an organic solvent needs to be used for extraction to obtain salicyl alcohol. This process has the disadvantages of many steps, large amounts of wastewater and large amounts of organic solvents. The process of preparing salicyl alcohol by hydrogenation using salicylaldehyde as a raw material is simple and has high atomic utilization. The hydrogenation reaction of salicylaldehyde includes a direct hydrogenation method, that is, a process of reducing it to alcohol using hydrogen as a hydrogen source. However, the benzene ring in salicylaldehyde is also easily hydrogenated, resulting in the generation of more by-products. Another is the MPV transfer hydrogenation reaction, which uses cheap and safe alcohol compounds as hydrogen sources to convert aldehyde groups into corresponding alcohols with high selectivity. At present, most of the substrates for hydrogenation conversion of carbonyl compounds such as aldehydes and ketones studied are mostly furfural. For example, CN116332864A synthesized a zirconium-nitrogen coordination catalyst (Zr-MM) with Zr as an active metal and a nitrogen-containing ligand as an organic ligand, which can effectively catalyze the conversion of furfural into furfuryl alcohol. The aldehyde group of furfural is located on an unsaturated furfural ring, and this structure makes the electron cloud density of the aldehyde group higher, making it easier to accept hydrogen atoms for addition reaction. The aldehyde group of salicylaldehyde is connected to a benzene ring, and the conjugation effect and stability of the benzene ring reduce the reactivity of the aldehyde group, making the hydrogenation process more difficult. Therefore, the MPV transfer hydrogenation reaction of salicylaldehyde is rarely reported.

[0003] In recent years, nitrogen-carbon materials have attracted extensive attention and applications in the field of catalytic research due to their unique electronic and chemical properties. On the one hand, the introduction of nitrogen species can effectively regulate the acid-base properties of the catalyst and improve its ability to activate reactants; on the other hand, nitrogen species can interact with metal components to improve the dispersion and stability of metal components. However, at present, research on nitrogen-carbon materials at home and abroad is mainly focused on the field of electrocatalysis, such as fuel cells and water electrolysis, and there is little research on thermal catalysis.

[0004] The present invention uses green and pollution-free biomass-based nitrogen-carbon materials and zirconium salts as precursors, and prepares a zirconium-based catalyst that can efficiently catalyze the MPV transfer hydrogenation reaction of salicylaldehyde through hydrothermal carbonization and high-temperature thermal cracking methods. Salicylaldehyde can make the yield of salicyl alcohol reach more than 97% at 170°C. Summary of the invention

[0005] The present invention aims to solve the problems of low catalyst activity, low product selectivity, expensive catalyst price and complicated preparation process in the prior art of salicylaldehyde MPV transfer hydrogenation reaction, and provides a method for efficiently catalyzing MPV transfer hydrogenation reaction by using biomass-based nitrogen-carbon material-loaded zirconium oxide as a catalyst. The catalyst preparation process is simple, the nitrogen-carbon precursor is green and economical, the catalytic activity and yield are high, and it has good practical application value.

[0006] The technical solution adopted by the present invention is:

[0007] A method for preparing a biomass-based nitrogen-carbon material-supported zirconium-based catalyst for salicylaldehyde MPV transfer hydrogenation reaction, the method is carried out according to the following steps:

[0008] (1) weighing a nitrogen-carbon precursor and a zirconium salt and dissolving them in a 5 wt % acetic acid solution at room temperature;

[0009] (2) After being uniformly dissolved, the solution is transferred to a hydrothermal kettle for hydrothermal carbonization;

[0010] (3) After the hydrothermal carbonization is completed, the mixture is centrifuged and dried and then placed in a tubular furnace. Under an inert atmosphere, the temperature is raised from room temperature to a specified temperature. After 3 hours, a zirconium-based catalyst is obtained, which is denoted as ZrO2 / NC_T, where T is a different calcination temperature.

[0011] As a limitation of the present invention, the nitrogen-carbon precursor described in step (1) of the present invention is one of chitosan and chitin; the zirconium salt is an inorganic zirconium salt or an organic zirconium salt, specifically one of zirconium oxychloride, zirconium chloride, zirconium ethanol, and zirconium acetylacetonate, preferably zirconium oxychloride; the mass ratio of zirconium salt to nitrogen-carbon precursor is 0.2 to 2, preferably 1.0.

[0012] As a limitation of the present invention, the hydrothermal carbonization in step (2) of the present invention is carried out at 120-210°C, preferably 180°C.

[0013] As a limitation of the present invention, the calcination temperature in step (3) of the present invention is 600-800°C, preferably 750°C.

[0014] The application of the prepared biomass-based nitrogen-carbon material supported zirconium-based catalyst in the transfer hydrogenation reaction of salicylaldehyde MPV is specifically applied as follows:

[0015] (1) adding salicylaldehyde substrate, zirconium-based catalyst and alcohol solvent into a batch autoclave, replacing the gas with nitrogen and then filling with nitrogen with an initial pressure of 0.8 MPa;

[0016] (2) Under stirring, the reaction temperature is set at 130-170° C. and the reaction time is 2-8 h. After the reaction is completed, the reactor is quickly cooled to room temperature and the product is analyzed by gas chromatography.

[0017] As a further limitation of the present invention, the mass molar ratio of the catalyst to the salicylaldehyde substrate in step (1) of the present invention is 50-100 mg:2 mmol.

[0018] As a further limitation of the present invention, the molar volume ratio of the salicylaldehyde substrate to the alcohol solvent in step (1) of the present invention is 2 mmol:10 mL.

[0019] As a further limitation of the present invention, the solvent described in step (1) of the present invention is one of ethanol, isopropanol and sec-butanol, preferably isopropanol.

[0020] As a further limitation of the present invention, the reaction temperature of step (2) of the present invention is 170° C. and the reaction time is 5 h.

[0021] The method for preparing the zirconium-based catalyst provided by the present invention has the following advantages compared with the traditional catalyst:

[0022] Under mild reaction conditions, the zirconium-based catalyst prepared by this method has good catalytic performance for the MPV transfer hydrogenation reaction of salicylaldehyde. When the salicylaldehyde is reacted at 170°C for 5 hours, a salicylaldehyde conversion rate of 99.2% can be achieved, and the selectivity for salicyl alcohol can reach a maximum of 98.1%. At the same time, this method also has the advantages of simple catalyst preparation process, green, cheap and easy-to-obtain raw materials, and wide substrate universality. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 XRD patterns of zirconium-based catalysts at different calcination temperatures;

[0024] Figure 2 TEM image of ZrO2 / NC prepared with chitin as nitrogen-carbon precursor. DETAILED DESCRIPTION

[0025] The present invention will be further described with reference to the following examples, but it should be understood that these examples are only for illustration and should not be construed as limitations of the present invention.

[0026] In the present invention, the ZrO2 / NC_T catalyst is synthesized by hydrothermal carbonization and high-temperature thermal cracking process. Different ZrO2 / NC_T catalysts can be obtained by adjusting parameters such as the ratio of zirconium salt and nitrogen-carbon precursor, hydrothermal temperature and thermal cracking temperature during the synthesis process.

[0027] Examples 1-5

[0028] The effects of different nitrogen-carbon precursors and zirconium precursors on the conversion rate of salicylaldehyde and the selectivity of salicyl alcohol are as follows:

[0029] Preparation scheme of ZrO2 / NC_750 catalyst: Weigh 1.5g of nitrogen-carbon precursor and 1.5g of zirconium salt precursor and dissolve them in 50mL of 5wt% acetic acid solution at room temperature. After stirring for 1h, transfer the mixture to a hydrothermal autoclave for carbonization, and keep the temperature at 180℃ for 8h. After the hydrothermal carbonization, quickly put it into ice water to cool it down, pour the mixture into a petri dish, and dry it in an oven at 80℃ overnight. Grind the obtained solid in a mortar, then put the powder into a tubular furnace and heat it from room temperature to 750℃ at 2.0℃ / min, and maintain it for 2h. The obtained black powder is recorded as ZrO2 / NC_750.

[0030] 2mmol salicylaldehyde, 100mg ZrO2 / NC_750 catalyst, 0.8MPa N2, and 10mL isopropanol were placed in a 50mL intermittent high-pressure reactor, the reaction device was installed, the temperature was raised to 170℃, and the reaction was stirred for 5h. After the reaction, the product was quantitatively analyzed by gas chromatography.

[0031] Table 1 Effects of different nitrogen-carbon precursors and zirconium precursors on salicylaldehyde conversion and salicyl alcohol selectivity

[0032] Example Nitrogen Carbon Precursor Zirconium Precursor Conversion rate (%) Selectivity (%) 1 Chitosan Zirconium oxychloride 95.4 92.4 2 Chitosan Zirconium oxychloride 99.2 98.1 3 Chitosan Zirconium chloride 97.1 97.2 4 Chitosan Zirconium Ethoxide 94.3 96.1 5 Chitosan Zirconium acetylacetonate 92.8 95.4

[0033] It can be seen from Table 1 that chitin and chitosan as nitrogen-carbon precursors can effectively catalyze the conversion of salicylaldehyde into salicyl alcohol, and chitosan has a better catalytic effect when used as a nitrogen-carbon precursor; among different zirconium precursors, zirconium oxychloride has a better effect.

[0034] Embodiment 6-8

[0035] The effect of the ratio of chitosan and zirconium oxychloride on the conversion rate of salicylaldehyde and the selectivity of salicyl alcohol was studied. The specific steps are as follows:

[0036] The catalyst preparation of Examples 6-8 is the same as that of Example 2, except that the mass of zirconium oxychloride is changed to 0.3g, 0.8g, and 3.0g.

[0037] 2mmol salicylaldehyde, 100mg ZrO2 / NC_750 catalyst, 0.8MPa N2, and 10mL isopropanol were placed in a 50mL intermittent high-pressure reactor, the reaction device was installed, the temperature was raised to 170℃, and the reaction was stirred for 5h. After the reaction, the product was quantitatively analyzed by gas chromatography.

[0038] Table 2 Effect of the ratio of chitosan and zirconium oxychloride on the conversion of salicylaldehyde and selectivity of salicyl alcohol

[0039] Example Zirconium oxychloride mass (g) Conversion rate (%) Selectivity (%) 6 0.3 70.5 92.3 7 0.8 92.5 97.2 2 1.5 99.2 98.1 8 3.0 91.8 95.7

[0040] It can be seen from Table 2 that the ratio of the nitrogen-carbon precursor to zirconium oxychloride has a great influence on the conversion rate of salicylaldehyde. When the mass of zirconium oxychloride is 1.5 g, that is, the mass ratio of zirconium salt to the nitrogen-carbon precursor is 1.0, the catalytic performance is the best.

[0041] Examples 9-11

[0042] The effect of hydrothermal carbonization temperature on the conversion rate of salicylaldehyde and the selectivity of salicyl alcohol is as follows:

[0043] The catalyst preparation of Examples 9-11 is the same as that of Example 2, except that the hydrothermal carbonization temperature of 180°C is changed to 120°C, 150°C, and 210°C.

[0044] 2mmol salicylaldehyde, 100mg ZrO2 / NC_750 catalyst, 0.8MPa N2, and 10mL isopropanol were placed in a 50mL intermittent high-pressure reactor, the reaction device was installed, the temperature was raised to 170℃, and the reaction was stirred for 5h. After the reaction, the product was quantitatively analyzed by gas chromatography.

[0045] Table 3 Effect of hydrothermal carbonization temperature on salicylaldehyde conversion and salicyl alcohol selectivity

[0046] Example Hydrothermal carbonization temperature (℃) Conversion rate (%) Selectivity (%) 9 120 59.2 91.5 10 150 79.4 95.6 2 180 99.2 98.1 11 210 90.7 97.2

[0047] It can be seen from Table 3 that the hydrothermal carbonization temperature has a great influence on the conversion rate of salicylaldehyde. When the carbonization temperature is 180 °C, the catalytic performance is the best.

[0048] Examples 12-15

[0049] The effect of thermal cracking temperature on the conversion rate of salicylaldehyde and the selectivity of salicyl alcohol is as follows:

[0050] The catalyst preparation of Examples 12-15 is the same as that of Example 2, except that the thermal cracking temperature of 750°C is changed to 600°C, 650°C, 700°C, and 800°C.

[0051] 2mmol salicylaldehyde, 100mg ZrO2 / NC_750 catalyst, 0.8MPa N2, and 10mL isopropanol were placed in a 50mL intermittent high-pressure reactor, the reaction device was installed, the temperature was raised to 170℃, and the reaction was stirred for 5h. After the reaction, the product was quantitatively analyzed by gas chromatography.

[0052] Table 4 Effect of thermal cracking temperature on salicylaldehyde conversion and salicyl alcohol selectivity

[0053]

[0054]

[0055] It can be seen from Table 4 that the thermal cracking temperature has a great influence on the catalytic performance. When the thermal cracking temperature of the catalyst is 750°C, the conversion rate of salicylaldehyde and the selectivity of salicyl alcohol are the highest.

[0056] Examples 16-18

[0057] The catalysts of Examples 16-18 were prepared in the same manner as in Example 2. The effects of different reaction temperatures on the conversion rate of salicylaldehyde and the selectivity of salicyl alcohol were studied, and the specific steps were as follows:

[0058] 2mmol salicylaldehyde, 100mg ZrO2 / NC_750 catalyst, 0.8MPa N2, and 10mL isopropanol were placed in a 50mL intermittent high-pressure reactor, the reaction device was installed, the temperature was raised to 130-170℃, and the reaction was stirred for 5h. After the reaction, the product was quantitatively analyzed by gas chromatography.

[0059] Table 5 Effect of different reaction temperatures on salicylaldehyde conversion and salicyl alcohol selectivity

[0060] Example Reaction temperature (℃) Conversion rate (%) Selectivity (%) 16 130 72.1 92.3 17 140 81.2 95.9 18 160 92.5 97.5 2 170 99.2 98.1

[0061] It can be seen from Table 5 that with the increase of reaction temperature, the conversion rate of salicylaldehyde gradually increases, and the selectivity of salicyl alcohol is above 90%.

[0062] Examples 19-21

[0063] The catalysts of Examples 19-21 were prepared in the same manner as in Example 2. The effects of different reaction times on the conversion rate of salicylaldehyde and the selectivity of salicyl alcohol were studied, and the specific steps were as follows:

[0064] 2mmol salicylaldehyde, 100mg ZrO2 / NC_750 catalyst, 0.8MPa N2, and 10mL isopropanol were placed in a 50mL intermittent high-pressure reactor. The reaction device was installed and the temperature was raised to 170℃. After reacting for 0.5 to 5h, gas chromatography was used for quantitative analysis.

[0065] Table 6 Effect of different reaction times on salicylaldehyde conversion and salicyl alcohol selectivity

[0066] Example Reaction time (h) Conversion rate (%) Selectivity (%) 19 0.5 59.2 97.2 20 1 79.2 98.2 21 3 87.5 97.5 2 5 99.2 98.1

[0067] It can be seen from Table 6 that when the reaction time is 5 h, the conversion rate of salicylaldehyde and the selectivity of salicyl alcohol are the highest.

[0068] Examples 22-23

[0069] The catalyst preparation of Examples 22-23 is the same as that of Example 2. The effects of different alcohol solvents on the conversion rate of salicylaldehyde and the selectivity of salicyl alcohol are studied, and the specific steps are as follows:

[0070] 2mmol salicylaldehyde, 100mg ZrO2 / NC_750 catalyst, 0.8MPa N2, and 10mL alcohol solvent were placed in a 50mL intermittent high-pressure reactor. The reaction device was installed and the temperature was raised to 170℃. After reacting for 5h, gas chromatography was used for quantitative analysis.

[0071] Table 7 Effect of different reaction alcohol solvents on salicylaldehyde conversion and salicyl alcohol selectivity

[0072] Example Alcohol solvent Conversion rate (%) Selectivity (%) 22 Ethanol 85.7 95.6 2 Isopropyl alcohol 99.2 98.1 23 Sec-Butanol 93.5 97.2

[0073] Table 7 shows that when isopropanol is used as solvent (hydrogen donor), the catalytic performance is the best.

[0074] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a biomass-based nitrogen-carbon material-supported zirconium-based catalyst for the transfer hydrogenation reaction of salicylaldehyde MPV, characterized in that: The catalyst is prepared according to the following steps: (1) weighing a nitrogen-carbon precursor and a zirconium salt and dissolving them in an acetic acid solution at room temperature to obtain a mixed solution after the mixture is uniformly dissolved, and transferring the mixed solution to a hydrothermal kettle for hydrothermal carbonization; (2) After the hydrothermal carbonization is completed, the product is placed in a tubular furnace after centrifugation and drying, and calcined under an inert atmosphere to obtain a zirconium-based catalyst, denoted as ZrO2 / NC_T, where T is a different calcination temperature; the calcination temperature is 600-800°C; the nitrogen-carbon precursor is one of chitosan and chitin.

2. The method for preparing a biomass-based nitrogen-carbon material-supported zirconium-based catalyst for the transfer hydrogenation reaction of salicylaldehyde MPV according to claim 1, characterized in that: The zirconium salt described in step (1) is an inorganic zirconium salt or an organic zirconium salt, specifically one of zirconium oxychloride, zirconium chloride, zirconium ethanol, and zirconium acetylacetonate.

3. The method for preparing a biomass-based nitrogen-carbon material-supported zirconium-based catalyst for the transfer hydrogenation reaction of salicylaldehyde MPV according to claim 1, characterized in that: The mass ratio of the zirconium salt and the nitrogen-carbon precursor described in step (1) is 0.2 to 2:

1.

4. The method for preparing a biomass-based nitrogen-carbon material-supported zirconium-based catalyst for the transfer hydrogenation reaction of salicylaldehyde MPV according to claim 1, characterized in that: The hydrothermal carbonization temperature in step (1) is 120-210°C.

5. The method for preparing a biomass-based nitrogen-carbon material-supported zirconium-based catalyst for the transfer hydrogenation reaction of salicylaldehyde MPV according to claim 1, characterized in that: The calcination temperature in step (2) is 750°C.

6. Use of a biomass-based nitrogen-carbon material-supported zirconium-based catalyst prepared according to the method of any one of claims 1 to 5 in the transfer hydrogenation reaction of salicylaldehyde MPV.

7. The use according to claim 6, characterized in that: The salicylaldehyde substrate, zirconium-based catalyst and alcohol solvent are added to a high-pressure reactor, which is sealed and filled with nitrogen with an initial pressure of 0.8 MPa after replacing the gas with nitrogen. Under stirring, the reactor is raised to a specified temperature. After a certain reaction time, the reactor is quickly cooled to room temperature, and the product is analyzed by gas chromatography.

8. The use according to claim 7, characterized in that: The mass molar ratio of the zirconium-based catalyst to the substrate is 50-100 mg: 2 mmol; the alcohol solvent is one of ethanol, isopropanol and sec-butanol; the reaction temperature is 130-170° C.; and the reaction time is 2-8 hours.

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