A catalyst for the hydrogenation of maleic anhydride to succinic anhydride and its preparation method

Abstract

This invention provides a catalyst for the hydrogenation of maleic anhydride to succinic anhydride and its preparation method, belonging to the field of catalyst technology. The preparation method includes the following steps: S1, immersing activated carbon in a 77-82% (w / w) phosphoric acid solution for 1-1.2 hours, then filtering to obtain acid-soaked activated carbon; S2, taking 50g of the acid-soaked activated carbon obtained in S1, dispersing it in 460-500mL of water, adding 0.5-0.8g of an aminosilane coupling agent and 9-11g of NiCl2·6H2O while stirring, and continuing to stir for 10-12 minutes to obtain a mixed solution; S3, adding sodium hydroxide aqueous solution to the mixed solution obtained in S2 until the pH reaches 10, continuing to stir for 5.5-6 hours, filtering, washing with water until neutral, and drying to obtain the catalyst; the catalyst for the hydrogenation of maleic anhydride to succinic anhydride is subjected to high-temperature reduction activation treatment before use. This invention can effectively improve catalytic efficiency, increase the conversion rate of maleic anhydride, and improve the selectivity of succinic anhydride.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalysts, and particularly relates to a catalyst for preparing succinic anhydride through hydrogenation of maleic anhydride and a preparation method thereof. BACKGROUND

[0002] Biodegradable plastics are ushering in a major development opportunity. As a top-notch biodegradable plastic material, polybutylene succinate (PBS) rapidly becomes a general-purpose biodegradable plastic research hotspot material that can be widely applied due to excellent mechanical properties, heat resistance, and good processing performance. As the main raw material for producing polybutylene succinate (PBS), the market demand for succinic anhydride is also increasing rapidly.

[0003] The production methods of succinic anhydride mainly include biological fermentation, succinic acid dehydration, and maleic anhydride catalytic hydrogenation. Among them, the biological fermentation method has been eliminated due to its low yield; the succinic acid dehydration method is gradually eliminated due to long process, large investment, difficult operation, low yield, and unstable quality. The maleic anhydride catalytic hydrogenation method is a continuous new process for forming succinic anhydride by selective hydrogenation with maleic anhydride as the raw material, and the chemical equation is as follows:

[0004]

[0005] Succinic anhydride is the product of hydrogenation of maleic anhydride, and succinic anhydride can also rapidly react with hydrogen to form gamma-butyrolactone. Therefore, it is particularly crucial to select a catalyst with high selectivity for succinic anhydride and prevent deep hydrogenation of maleic anhydride. SUMMARY

[0006] To solve the problems in the background art, the application provides a catalyst for preparing succinic anhydride through hydrogenation of maleic anhydride and a preparation method thereof, which effectively improves the catalytic efficiency, increases the conversion rate of maleic anhydride, and improves the selectivity of succinic anhydride.

[0007] To achieve the above-mentioned purpose, in a first aspect, the application provides a preparation method of a catalyst for preparing succinic anhydride through hydrogenation of maleic anhydride, which comprises the following steps:

[0008] S1, active carbon is immersed in a phosphoric acid solution with a mass concentration of 77-82%, and after soaking for 1-1.2 h, it is filtered out to obtain acid-soaked active carbon;

[0009] S2, 50 g of the acid-soaked active carbon obtained in S1 is dispersed in 460-500 mL of water, and 0.5-0.8 g of an amino-containing silane coupling agent and 9-11 g of NiCl2·6H2O are added under stirring, and the stirring is continued for 10-12 min to obtain a mixed solution;

[0010] S3, adding sodium hydroxide solution to the mixture obtained in S2 until the pH is 10, continuing to stir for 5.5-6h, and then filtering and washing with water until neutral and no Cl- is detected, and drying to obtain the catalyst for preparing succinic anhydride by hydrogenation of maleic anhydride. - The catalyst for preparing succinic anhydride by hydrogenation of maleic anhydride is subjected to high-temperature reduction activation treatment before use.

[0011] The catalyst for preparing succinic anhydride by hydrogenation of maleic anhydride is subjected to high-temperature reduction activation treatment before use.

[0012] Further, the specific operation steps of the high-temperature reduction activation treatment are as follows: reducing the catalyst for preparing succinic anhydride by hydrogenation of maleic anhydride with hydrogen at 120-150℃ for 1.8-2.3h, then filtering out, placing in a high-temperature furnace, heating, and then cooling to room temperature.

[0013] Further, the heating is specifically heating to 460-480℃ at a heating rate of 13-15℃ / min.

[0014] Further, in S1, during the soaking process, uniform stirring is performed at a stirring speed of 100-120r / min for 1-2min every 10min.

[0015] Further, in S2, the amino-containing silane coupling agent is γ-aminopropyl triethoxysilane.

[0016] Further, in S2, the stirring speed is 150-180r / min.

[0017] Further, in S3, the mass fraction of the sodium hydroxide solution is 0.5-0.8%.

[0018] Further, in S3, the specific operation of drying is vacuum drying at 55-65℃ for 10-12h.

[0019] In a second aspect, the present application provides a catalyst for preparing succinic anhydride by hydrogenation of maleic anhydride, which is prepared by the above method.

[0020] The present application has the following beneficial effects:

[0021] In the preparation of the catalyst for preparing succinic anhydride by hydrogenation of maleic anhydride, the activated carbon is first soaked in a high-concentration (mass concentration 77-82%) phosphoric acid solution for 1-1.2h to obtain acid-soaked activated carbon as a catalyst carrier.

[0022] In the process of loading nickel, an amino-containing silane coupling agent is introduced, on the one hand, the amino group can react with the functional groups on the surface of the activated carbon to form a stable chemical bond, thereby forming a stable siloxane network structure on the surface of the activated carbon, and the surface of the activated carbon is modified to improve its thermal stability; on the other hand, nitrogen doping can also change the surface chemical properties of the activated carbon and enhance the interaction between the activated carbon and metal ions, thereby further improving the stability of the activated carbon at high temperatures.

[0023] In this way, the soaking of the activated carbon in the high-concentration phosphoric acid solution and the introduction of the amino-containing silane coupling agent have a synergistic effect, which synergistically improves the catalytic efficiency of the prepared catalyst and synergistically improves the maleic anhydride conversion rate and the succinic anhydride selectivity when the catalyst is used in the process of preparing succinic anhydride by hydrogenation of maleic anhydride. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A comparison trend chart of test data of the maleic anhydride conversion rate and the succinic anhydride selectivity when the catalyst prepared in the test examples of the present application, i.e., examples 1-3 and comparative examples 1-5, is used in the process of preparing succinic anhydride by hydrogenation of maleic anhydride. DETAILED DESCRIPTION

[0025] The present application will be further described in detail below in combination with examples.

[0026] The raw materials of the examples and comparative examples of the present application are all ordinary commercial products unless otherwise specified.

[0027] Example 1: A preparation method of a catalyst for preparing succinic anhydride by hydrogenation of maleic anhydride, comprising the following steps:

[0028] S1, immerse the activated carbon in a phosphoric acid solution with a mass concentration of 80%, uniformly stir at a stirring speed of 110 r / min every 10 min, and after 1.1 h of soaking, filter out to obtain acid-soaked activated carbon.

[0029] S2, take 50 g of the acid-soaked activated carbon obtained in S1, disperse it in 480 mL of water, and add 0.7 g of γ-aminopropyltriethoxysilane and 10 g of NiCl2·6H2O under stirring at 160 r / min, and continue stirring for 11 min to obtain a mixed solution.

[0030] S3, add a 0.6% mass fraction sodium hydroxide aqueous solution to the mixed solution obtained in S2 until the pH is 10, continue stirring for 5.8 h, filter, wash with water until neutral and no Cl - - is detected, and vacuum dry at 60℃ for 11 h to obtain a catalyst for preparing succinic anhydride by hydrogenation of maleic anhydride.

[0031] The catalyst for preparing succinic anhydride by hydrogenation of maleic anhydride is subjected to high-temperature reduction activation treatment before use. The specific operation steps are as follows: the catalyst for preparing succinic anhydride by hydrogenation of maleic anhydride is reduced by hydrogen at 135℃ for 2h, then filtered out, placed in a high-temperature furnace, heated to 470℃ at a heating rate of 14℃ / min, and then cooled to room temperature.

[0032] Example 2: The difference between this example and example 1 is that a preparation method of a catalyst for preparing succinic anhydride by hydrogenation of maleic anhydride, comprising the following steps:

[0033] S1, immerse the activated carbon in a phosphoric acid solution with a mass concentration of 77%, uniformly stir at a stirring speed of 100r / min every 10min, soak for 1.2h, then filter out to obtain acid-foamed activated carbon.

[0034] S2, take 50g of the acid-foamed activated carbon obtained in S1, disperse in 460mL of water, add 0.5g of γ-aminopropyltriethoxysilane and 9g of NiCl2·6H2O under stirring at 150r / min, continue stirring for 10min to obtain a mixed solution.

[0035] S3, add a sodium hydroxide aqueous solution with a mass fraction of 0.5% to the mixed solution obtained in S2 until the pH is 10, continue stirring for 5.5h, then filter, wash with water until neutral and no Cl - is detected, vacuum dry at 55℃ for 12h to obtain the catalyst for preparing succinic anhydride by hydrogenation of maleic anhydride.

[0036] Example 3: The difference between this example and example 1 is that a preparation method of a catalyst for preparing succinic anhydride by hydrogenation of maleic anhydride, comprising the following steps:

[0037] S1, immerse the activated carbon in a phosphoric acid solution with a mass concentration of 82%, uniformly stir at a stirring speed of 120r / min every 10min, soak for 1h, then filter out to obtain acid-foamed activated carbon.

[0038] S2, take 50g of the acid-foamed activated carbon obtained in S1, disperse in 500mL of water, add 0.8g of γ-aminopropyltriethoxysilane and 11g of NiCl2·6H2O under stirring at 180r / min, continue stirring for 12min to obtain a mixed solution.

[0039] S3, add a sodium hydroxide aqueous solution with a mass fraction of 0.8% to the mixed solution obtained in S2 until the pH is 10, continue stirring for 5.5h, then filter, wash with water until neutral and no Cl - is detected, vacuum dry at 65℃ for 10h to obtain the catalyst for preparing succinic anhydride by hydrogenation of maleic anhydride.

[0040] Comparative Example 1: The difference between this comparative example and Example 1 is that the mass concentration of the phosphoric acid solution is 60%, and the immersion time is 40 min; and the γ-aminopropyl triethoxysilane is deleted.

[0041] Specifically, a preparation method of a catalyst for preparing succinic anhydride by hydrogenation of maleic anhydride comprises the following steps:

[0042] S1, immerse the activated carbon in a phosphoric acid solution with a mass concentration of 60%, uniformly stir at a stirring speed of 110 r / min every 10 min for 1.5 min, filter out after immersion for 40 min, and obtain acid-foamed activated carbon.

[0043] S2, take 50 g of the acid-foamed activated carbon obtained in S1, disperse in 480 mL of water, add 10 g of NiCl2·6H2O under stirring at 160 r / min, continuously stir for 11 min, and obtain a mixed solution.

[0044] S3, add a sodium hydroxide aqueous solution with a mass fraction of 0.6% to the mixed solution obtained in S2 until the pH is 10, continue to stir for 5.8 h, filter, wash with water until neutral and no Cl - is detected, vacuum dry at 60°C for 11 h, and obtain the catalyst for preparing succinic anhydride by hydrogenation of maleic anhydride.

[0045] Comparative Example 2: The difference between this comparative example and Example 1 is that the γ-aminopropyl triethoxysilane is deleted.

[0046] Specifically, a preparation method of a catalyst for preparing succinic anhydride by hydrogenation of maleic anhydride comprises the following steps:

[0047] S1, immerse the activated carbon in a phosphoric acid solution with a mass concentration of 80%, uniformly stir at a stirring speed of 110 r / min every 10 min for 1.5 min, filter out after immersion for 1.1 h, and obtain acid-foamed activated carbon.

[0048] S2, take 50 g of the acid-foamed activated carbon obtained in S1, disperse in 480 mL of water, add 10 g of NiCl2·6H2O under stirring at 160 r / min, continuously stir for 11 min, and obtain a mixed solution.

[0049] S3, add a sodium hydroxide aqueous solution with a mass fraction of 0.6% to the mixed solution obtained in S2 until the pH is 10, continue to stir for 5.8 h, filter, wash with water until neutral and no Cl - is detected, vacuum dry at 60°C for 11 h, and obtain the catalyst for preparing succinic anhydride by hydrogenation of maleic anhydride.

[0050] Comparative Example 3: The difference between this comparative example and Example 1 is that the mass concentration of the phosphoric acid solution is 60%, and the immersion time is 40 min.

[0051] Specifically, a method for preparing a catalyst for the hydrogenation of maleic anhydride to succinic anhydride includes the following steps:

[0052] S1. Immerse activated carbon in a 60% phosphoric acid solution. Stir at a constant speed of 110 r / min for 1.5 min every 10 min. After soaking for 40 min, filter out to obtain acid-soaked activated carbon.

[0053] S2. Take 50g of the acid-soaked activated carbon obtained in S1, disperse it in 480mL of water, add 0.7g of γ-aminopropyltriethoxysilane and 10g of NiCl2·6H2O while stirring at 160r / min, and continue stirring for 11min to obtain a mixed solution.

[0054] S3. Add a 0.6% sodium hydroxide aqueous solution to the mixture obtained in S2 until the pH reaches 10. Continue stirring for 5.8 hours, then filter and wash with water until neutral and Cl- is undetectable. - The catalyst for the hydrogenation of maleic anhydride to succinic anhydride was obtained by vacuum drying at 60°C for 11 hours.

[0055] Comparative Example 4: The difference between this comparative example and Example 1 is that γ-aminopropyltriethoxysilane is replaced with γ-glycidoxypropyltrimethoxysilane.

[0056] Specifically, a method for preparing a catalyst for the hydrogenation of maleic anhydride to succinic anhydride includes the following steps:

[0057] S1. Immerse activated carbon in a phosphoric acid solution with a mass concentration of 80%. Stir at a constant speed of 110 r / min for 1.5 min every 10 min. After soaking for 1.1 h, filter out to obtain acid-soaked activated carbon.

[0058] S2. Take 50g of the acid-soaked activated carbon obtained in S1, disperse it in 480mL of water, add 0.7g of γ-glycidyl etheroxypropyltrimethoxysilane and 10g of NiCl2·6H2O while stirring at 160r / min, and continue stirring for 11min to obtain a mixed solution.

[0059] S3. Add a 0.6% sodium hydroxide aqueous solution to the mixture obtained in S2 until the pH reaches 10. Continue stirring for 5.8 hours, then filter and wash with water until neutral and Cl- is undetectable. - The catalyst for the hydrogenation of maleic anhydride to succinic anhydride was obtained by vacuum drying at 60°C for 11 hours.

[0060] Comparative Example 5: The difference between this comparative example and Example 1 is that γ-aminopropyltriethoxysilane is replaced with methyltriethoxysilane.

[0061] Specifically, a method for preparing a catalyst for the hydrogenation of maleic anhydride to succinic anhydride includes the following steps:

[0062] S1. Immerse activated carbon in a phosphoric acid solution with a mass concentration of 80%. Stir at a constant speed of 110 r / min for 1.5 min every 10 min. After soaking for 1.1 h, filter out to obtain acid-soaked activated carbon.

[0063] S2. Take 50g of the acid-soaked activated carbon obtained in S1, disperse it in 480mL of water, add 0.7g of methyltriethoxysilane and 10g of NiCl2·6H2O while stirring at 160r / min, and continue stirring for 11min to obtain a mixed solution.

[0064] S3. Add a 0.6% sodium hydroxide aqueous solution to the mixture obtained in S2 until the pH reaches 10. Continue stirring for 5.8 hours, then filter and wash with water until neutral and Cl- is undetectable. - The catalyst for the hydrogenation of maleic anhydride to succinic anhydride was obtained by vacuum drying at 60°C for 11 hours.

[0065] Experimental Examples: Test Subjects: Catalysts prepared in Examples 1-3 and Comparative Examples 1-5.

[0066] Experimental method: Hydrogenation of maleic anhydride to succinic anhydride. A fixed-bed reactor was filled with 35g of a high-temperature reduction-activated catalyst. A 10wt% solution of maleic anhydride in diethylene glycol dimethyl ether was introduced to carry out the selective hydrogenation reaction of maleic anhydride. The reaction temperature was 80℃, the reaction pressure was 3MPa, the reaction time was 3h, and the maleic anhydride mass hourly space velocity was 1h⁻¹. -1 The hydrogen / maleic anhydride molar ratio was 30. Maleic anhydride conversion and succinic anhydride selectivity were both determined by gas chromatography.

[0067] Experimental results: see Table 1.

[0068] Table 1. Test data for the experimental cases

[0069]

[0070] Results Analysis: Analysis of Examples 1-3, combined with data from Table 1 and... Figure 1 As can be seen, the catalyst prepared by the present invention (Examples 1-3) is used in the process of maleic anhydride hydrogenation to succinic anhydride, and the maleic anhydride conversion rate is as high as 96.0% or more, and the succinic anhydride selectivity is as high as 98.1% or more.

[0071] Analysis of Example 1 and Comparative Examples 1-5, combined with data from Table 1 and Figure 1As can be seen from the comparison between Comparative Example 1 and Comparative Example 2, without the use of γ-aminopropyltriethoxysilane for modification, increasing the concentration of phosphoric acid used for soaking activated carbon from 60% to 80% and extending the soaking time from 40 min to 1.1 h will lead to a decrease in the catalytic efficiency of the final catalyst. Consequently, when this catalyst is used in the process of hydrogenating maleic anhydride to succinic anhydride, both the maleic anhydride conversion rate and the succinic anhydride selectivity will decrease.

[0072] This is because soaking activated carbon with phosphoric acid can form more micropores and mesopores in the carbon material, increasing its specific surface area and improving the catalyst's dispersibility. This, in turn, promotes the contact between reactants and active sites, thereby enhancing catalytic efficiency. However, excessively high phosphoric acid concentrations and prolonged soaking times can lead to an excessively increased specific surface area, resulting in a decrease in the material's thermal stability. Consequently, during catalyst activation (reduction) treatment, the high temperature can cause structural changes in the activated carbon, reducing the number of active sites and altering their properties, ultimately leading to a decrease in catalytic efficiency instead of an increase.

[0073] Comparison of Comparative Example 1 and Comparative Example 3 shows that when the concentration of phosphoric acid used for soaking activated carbon is 60% and the soaking time is 40 min, the addition of γ-aminopropyltriethoxysilane for modification has little effect on the catalytic efficiency of the final catalyst.

[0074] Comparison between Comparative Example 2 and Example 1 shows that when the concentration of phosphoric acid used for soaking activated carbon is 80% and the soaking time is 1.1 h, the addition of γ-aminopropyltriethoxysilane for modification can significantly improve the catalytic efficiency of the final catalyst. When this catalyst is used in the process of hydrogenating maleic anhydride to succinic anhydride, the conversion rate of maleic anhydride and the selectivity of succinic anhydride are significantly improved.

[0075] This is because the addition of γ-aminopropyltriethoxysilane can effectively modify the structure of activated carbon, thereby improving its thermal stability while maintaining its high specific surface area and abundant pore structure to meet the requirements of subsequent applications. Specifically, on the one hand, γ-aminopropyltriethoxysilane contains amino groups, which can react with functional groups on the surface of activated carbon to form stable chemical bonds, thus forming a stable siloxane network structure on the activated carbon surface, modifying the activated carbon surface and improving its thermal stability. On the other hand, nitrogen doping can also change the surface chemical properties of activated carbon, enhancing its interaction with metal ions, thereby further improving its stability at high temperatures.

[0076] As can be seen from the comparison between Example 1 and Comparative Example 4, replacing γ-aminopropyltriethoxysilane with γ-glycidoxypropyltrimethoxysilane will result in a decrease in the conversion rate of maleic anhydride and the selectivity of succinic anhydride when the catalyst is used in the process of hydrogenating maleic anhydride to succinic anhydride.

[0077] The inventors believe this is because γ-glycidoxypropyltrimethoxysilane contains epoxy groups, which function similarly to the amino groups in γ-aminopropyltriethoxysilane. These epoxy groups can react with the functional groups on the activated carbon surface to form stable chemical bonds, thereby creating a stable siloxane network structure on the activated carbon surface. This surface modification improves the thermal stability of the activated carbon. However, γ-glycidoxypropyltrimethoxysilane cannot achieve the nitrogen doping effect of γ-aminopropyltriethoxysilane.

[0078] A comparison with Comparative Example 5 shows that when the catalyst prepared by replacing it with methyltriethoxysilane is used in the process of hydrogenating maleic anhydride to succinic anhydride, the conversion rate of maleic anhydride and the selectivity of succinic anhydride further decrease.

[0079] The inventors believe that this is because methyltriethoxysilane contains only saturated alkyl groups, which makes it difficult to form chemical bonds with the functional groups on the surface of activated carbon, thus failing to achieve an effective surface modification effect and effectively improve the thermal stability of activated carbon.

[0080] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0081] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for producing a catalyst for the hydrogenation of maleic anhydride to succinic anhydride, characterized by, It comprises the following steps: S1, the activated carbon is immersed in a phosphoric acid solution with a mass concentration of 77-82%, and after soaking for 1-1.2 h, it is filtered out to obtain acid-soaked activated carbon; S2, 50 g of the acid-soaked activated carbon obtained in S1 is dispersed in 460-500 mL of water, and under stirring, 0.5-0.8 g of an amino-containing silane coupling agent and 9-11 g of NiCl2·6H2O are added, and the stirring is continued for 10-12 min to obtain a mixed solution; the amino-containing silane coupling agent is γ-aminopropyl triethoxysilane; S3, to the mixture obtained in S2 is added sodium hydroxide aqueous solution until the pH is 10, and the stirring is continued for 5.5-6 hours, then filtered, washed with water until neutral and no Cl - is dried, to obtain the catalyst for the hydrogenation of maleic anhydride to succinic anhydride. Before use, the catalyst for preparing succinic anhydride by hydrogenation of maleic anhydride is subjected to high-temperature reduction activation treatment, and the specific operation steps are as follows: the catalyst is reduced by hydrogen at 120-150℃ for 1.8-2.3 h, then filtered out, placed in a high-temperature furnace, and heated to 460-480℃ at a heating rate of 13-15℃ / min, and then cooled to room temperature.

2. The method for preparing the catalyst for the hydrogenation of maleic anhydride to succinic anhydride according to claim 1, characterized in that, In S1, during the soaking process, uniform stirring is carried out at a stirring speed of 100-120 r / min for 1-2 min every 10 min.

3. The method for preparing the catalyst for the hydrogenation of maleic anhydride to succinic anhydride according to claim 1, characterized in that, In S2, the stirring speed is 150-180 r / min.

4. The method for preparing the catalyst for the hydrogenation of maleic anhydride to succinic anhydride according to claim 1, characterized in that, In S3, the mass fraction of the sodium hydroxide aqueous solution is 0.5-0.8%.

5. The method for preparing the catalyst for the hydrogenation of maleic anhydride to succinic anhydride according to claim 1, characterized in that, In S3, the specific drying operation is vacuum drying at 55-65℃ for 10-12 h.

6. A catalyst for the hydrogenation of maleic anhydride to succinic anhydride, characterized in that, The preparation method is prepared by using any one of claims 1-5.

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