Catalyst for preparing butanedioic anhydride through maleic anhydride hydrogenation and preparation method thereof

Abstract

The invention provides a catalyst for preparing succinic anhydride through maleic anhydride hydrogenation and a preparation method of the catalyst, and belongs to the technical field of catalysts.The preparation method comprises the steps that S1, activated carbon is soaked in a phosphoric acid solution with the mass concentration of 77-82% for 1-1.2 h and then filtered out, and acid-soaked activated carbon is obtained; s2, taking 50 g of the acid-soaked activated carbon obtained in the S1, dispersing the acid-soaked activated carbon in 460-500 mL of water, adding 0.5-0.8 g of an amino-containing silane coupling agent and 9-11 g of NiCl2. 6H2O under stirring, and continuously stirring for 10-12 min to obtain a mixed solution; and S3, adding a sodium hydroxide aqueous solution into the mixed solution obtained in the S2 until the pH value is 10, continuously stirring for 5.5-6 hours, filtering, washing with water until the solution is neutral, and drying, thereby obtaining the product, before being used, the catalyst for preparing succinic anhydride by maleic anhydride hydrogenation is subjected to high-temperature reduction activation treatment. According to the invention, the catalytic efficiency can be effectively improved, and the selectivity of succinic anhydride is improved while the conversion rate of maleic anhydride is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and particularly relates to a catalyst for preparing succinic anhydride by hydrogenating maleic anhydride and a preparation method thereof. Background Art

[0002] Biodegradable plastics are facing a major development opportunity. As a leader in biodegradable plastic materials, polybutylene succinate (PBS) has rapidly become a hot research material for general biodegradable plastics that can be widely promoted and applied due to its excellent mechanical properties, heat resistance and good processing properties. As the main raw material for the production of polybutylene succinate (PBS), the market demand for succinic anhydride is also increasing sharply.

[0003] The main production methods of succinic anhydride include biological fermentation, succinic acid dehydration, maleic anhydride catalytic hydrogenation, etc. Among them, the biological fermentation method has a low yield and has been eliminated; the succinic acid dehydration method has a long process, large investment, difficult operation, low yield, and unstable quality, and is gradually being eliminated. The maleic anhydride catalytic hydrogenation method uses maleic anhydride as a raw material and selectively hydrogenates to form a continuous new process of succinic anhydride. Its chemical equation is as follows:

[0004] Succinic anhydride is the product of maleic anhydride hydrogenation, and succinic anhydride can also react quickly with hydrogen to form γ-butyrolactone. Therefore, it is particularly important to select a catalyst that has high selectivity for succinic anhydride and prevents deep hydrogenation of maleic anhydride. Summary of the invention

[0005] In order to solve the problems existing in the background technology, the present invention provides a catalyst for preparing succinic anhydride by hydrogenating maleic anhydride and a preparation method thereof, which effectively improves the catalytic efficiency, improves the maleic anhydride conversion rate, and improves the selectivity of succinic anhydride.

[0006] In order to achieve the above object, in a first aspect, the present invention provides a method for preparing a catalyst for hydrogenating maleic anhydride to produce succinic anhydride, comprising the following steps: S1. Immerse the activated carbon in a phosphoric acid solution with a mass concentration of 77-82% for 1-1.2 hours, filter out, and obtain acid-soaked activated carbon; S2, take 50g of the acid-soaked activated carbon obtained in S1, disperse it in 460-500mL of water, add 0.5-0.8g of an amino-containing silane coupling agent and 9-11g of NiCl2·6H2O under stirring, and continue stirring for 10-12min to obtain a mixed solution; S3, add sodium hydroxide aqueous solution to the mixed solution obtained in S2 until the pH is 10, continue stirring for 5.5-6 hours, filter, and wash with water until it is neutral and no Cl is detected - The catalyst for hydrogenating maleic anhydride to succinic anhydride is obtained by drying. Before use, the catalyst for the hydrogenation of maleic anhydride to succinic anhydride is subjected to high-temperature reduction activation treatment.

[0007] Further, the specific operation steps of the high-temperature reduction activation treatment are as follows: The catalyst for the hydrogenation of maleic anhydride to succinic anhydride is reduced with hydrogen at 120 - 150 °C for 1.8 - 2.3 h, then filtered out, placed in a high-temperature furnace, heated up, and then cooled to room temperature.

[0008] Further, the heating-up is specifically: heating up to 460 - 480 °C at a heating rate of 13 - 15 °C / min.

[0009] Further, in S1, during the soaking process, every 10 min, it is uniformly stirred at a stirring speed of 100 - 120 r / min for 1 - 2 min.

[0010] Further, in S2, the amino-functional silane coupling agent is γ-aminopropyltriethoxysilane.

[0011] Further, in S2, the stirring speed is 150 - 180 r / min.

[0012] Further, in S3, the mass fraction of the sodium hydroxide aqueous solution is 0.5 - 0.8%.

[0013] Further, in S3, the specific operation of drying is: drying under vacuum at 55 - 65 °C for 10 - 12 h.

[0014] In the second aspect, the present invention provides a catalyst for the hydrogenation of maleic anhydride to succinic anhydride, which is prepared by the above preparation method.

[0015] This application has the following beneficial effects: In the preparation of the catalyst for the hydrogenation of maleic anhydride to succinic anhydride of the present invention, activated carbon is first soaked in a high-concentration (mass concentration 77 - 82%) phosphoric acid solution for 1 - 1.2 h to obtain acid-soaked activated carbon as a catalyst carrier.

[0016] Then, an amino-functional silane coupling agent is introduced during the process of loading nickel. On the one hand, the amino group can react with the functional groups on the surface of activated carbon to form stable chemical bonds, thereby forming a stable siloxane network structure on the surface of activated carbon, performing surface modification on activated carbon, and improving its thermal stability; on the other hand, nitrogen doping can also change the surface chemical properties of activated carbon, enhance its interaction with metal ions, and thus further improve its stability at high temperatures.

[0017] In this way, a synergistic effect is produced between the immersion of activated carbon in a high-concentration phosphoric acid solution and the introduction of an amino-silane coupling agent, which synergistically improves the catalytic efficiency performance of the prepared catalyst and synergistically increases the maleic anhydride conversion rate and succinic anhydride selectivity when the catalyst is used in the process of hydrogenating maleic anhydride to succinic anhydride. Description of the Drawings

[0018] Figure 1 、Comparison trend chart of the test data of maleic anhydride conversion rate and succinic anhydride selectivity when the catalysts prepared in Examples 1-3 and Comparative Examples 1-5 in the test examples of the present invention are used in the process of hydrogenating maleic anhydride to succinic anhydride. Detailed Description of the Invention

[0019] The following further elaborates on the present application in conjunction with the examples.

[0020] Unless otherwise specified, the raw materials in the examples and comparative examples of the present application are all commercially available.

[0021] Example 1: A preparation method of a catalyst for hydrogenating maleic anhydride to succinic anhydride, comprising the following steps: S1. Immerse activated carbon in a phosphoric acid solution with a mass concentration of 80%, and stir evenly at a stirring speed of 110 r / min for 1.5 min every 10 min. After soaking for 1.1 h, filter to obtain acid-soaked activated carbon.

[0022] 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 continuously stir for 11 min to obtain a mixed solution.

[0023] S3. Add an aqueous sodium hydroxide 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, then filter, wash with water until neutral and no Cl - is detected. At 60 °C, vacuum dry for 11 h to obtain the catalyst for hydrogenating maleic anhydride to succinic anhydride.

[0024] Before use, the catalyst for hydrogenating maleic anhydride to succinic anhydride is subjected to high-temperature reduction activation treatment. The specific operation steps are as follows: Reduce the catalyst for hydrogenating maleic anhydride to succinic anhydride with hydrogen at 135 °C for 2 h, then filter it out, place it in a high-temperature furnace, heat it to 470 °C at a heating rate of 14 °C / min, and then cool it to room temperature.

[0025] Example 2: The difference between this example and Example 1 lies in: A preparation method of a catalyst for hydrogenating maleic anhydride to succinic anhydride, comprising the following steps: S1. Immerse the activated carbon in a phosphoric acid solution with a mass concentration of 77%. Stir it evenly at a stirring speed of 100 r / min for 2 min every 10 min. After soaking for 1.2 h, filter it to obtain acid-soaked activated carbon.

[0026] S2. Take 50 g of the acid-soaked activated carbon obtained in S1, disperse it in 460 mL of water, add 0.5 g of γ-aminopropyltriethoxysilane and 9 g of NiCl2·6H2O under stirring at 150 r / min, and continuously stir for 10 min to obtain a mixed solution.

[0027] S3. Add an aqueous sodium hydroxide solution with a mass fraction of 0.5% to the mixed solution obtained in S2 until the pH reaches 10. Continue stirring for 5.5 h, then filter, wash with water until neutral and no Cl - is detected. Dry it under vacuum at 55 °C for 12 h to obtain the catalyst for the hydrogenation of maleic anhydride to succinic anhydride.

[0028] Example 3: The difference between this example and Example 1 lies in: A preparation method of a catalyst for the hydrogenation of maleic anhydride to succinic anhydride, including the following steps: S1. Immerse the activated carbon in a phosphoric acid solution with a mass concentration of 82%. Stir it evenly at a stirring speed of 120 r / min for 1 min every 10 min. After soaking for 1 h, filter it to obtain acid-soaked activated carbon.

[0029] S2. Take 50 g of the acid-soaked activated carbon obtained in S1, disperse it in 500 mL of water, add 0.8 g of γ-aminopropyltriethoxysilane and 11 g of NiCl2·6H2O under stirring at 180 r / min, and continuously stir for 12 min to obtain a mixed solution.

[0030] S3. Add an aqueous sodium hydroxide solution with a mass fraction of 0.8% to the mixed solution obtained in S2 until the pH reaches 10. Continue stirring for 5.5 h, then filter, wash with water until neutral and no Cl - is detected. Dry it under vacuum at 65 °C for 10 h to obtain the catalyst for the hydrogenation of maleic anhydride to succinic anhydride.

[0031] Comparative Example 1: The difference between this comparative example and Example 1 lies in: The mass concentration of the phosphoric acid solution is 60%, and the soaking time is 40 min; and γ-aminopropyltriethoxysilane is deleted.

[0032] Specifically, a preparation method of a catalyst for the hydrogenation of maleic anhydride to succinic anhydride, including the following steps: S1. Immerse the activated carbon in a phosphoric acid solution with a mass concentration of 60%. Stir it evenly at a stirring speed of 110 r / min for 1.5 min every 10 min. After soaking for 40 min, filter it to obtain acid-soaked activated carbon.

[0033] S2. Take 50 g of the acid-treated activated carbon obtained in S1, disperse it in 480 mL of water, add 10 g of NiCl₂·6H₂O under stirring at 160 r / min, and continuously stir for 11 min to obtain a mixed solution.

[0034] S3. Add an aqueous sodium hydroxide solution with a mass fraction of 0.6% to the mixed solution obtained in S2 until the pH reaches 10, continue stirring for 5.8 h, then filter, wash with water until neutral and no Cl⁻ can be detected. - Stop when this is achieved, and then conduct vacuum drying at 60 °C for 11 h to obtain the catalyst for the hydrogenation of maleic anhydride to succinic anhydride.

[0035] Comparative Example 2: The difference between this comparative example and Example 1 is that γ-aminopropyltriethoxysilane is removed.

[0036] Specifically, a preparation method of a catalyst for the hydrogenation of maleic anhydride to succinic anhydride includes the following steps: S1. Immerse the activated carbon in a phosphoric acid solution with a mass concentration of 80%, stir evenly at a stirring speed of 110 r / min every 10 min for 1.5 min, filter after soaking for 1.1 h to obtain acid-treated activated carbon.

[0037] S2. Take 50 g of the acid-treated activated carbon obtained in S1, disperse it in 480 mL of water, add 10 g of NiCl₂·6H₂O under stirring at 160 r / min, and continuously stir for 11 min to obtain a mixed solution.

[0038] S3. Add an aqueous sodium hydroxide solution with a mass fraction of 0.6% to the mixed solution obtained in S2 until the pH reaches 10, continue stirring for 5.8 h, then filter, wash with water until neutral and no Cl⁻ can be detected. - Stop when this is achieved, and then conduct vacuum drying at 60 °C for 11 h to obtain the catalyst for the hydrogenation of maleic anhydride to succinic anhydride.

[0039] 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 soaking time is 40 min.

[0040] Specifically, a preparation method of a catalyst for the hydrogenation of maleic anhydride to succinic anhydride includes the following steps: S1. Immerse the activated carbon in a phosphoric acid solution with a mass concentration of 60%, stir evenly at a stirring speed of 110 r / min every 10 min for 1.5 min, filter after soaking for 40 min to obtain acid-treated activated carbon.

[0041] S2. Take 50 g of the acid-treated activated carbon obtained in S1, disperse it in 480 mL of water, add 0.7 g of γ-aminopropyltriethoxysilane and 10 g of NiCl₂·6H₂O under stirring at 160 r / min, and continuously stir for 11 min to obtain a mixed solution.

[0042] S3. Add an aqueous sodium hydroxide solution with a mass fraction of 0.6% to the mixed solution obtained in S2 until the pH reaches 10. Continue stirring for 5.8 h, then filter and wash with water until neutral and no Cl can be detected. - Then, under vacuum drying at 60 °C for 11 h, the catalyst for the hydrogenation of maleic anhydride to succinic anhydride is obtained.

[0043] Comparative Example 4: The difference between this comparative example and Example 1 is that γ-aminopropyltriethoxysilane is replaced by γ-glycidoxypropyltrimethoxysilane.

[0044] Specifically, a preparation method of a catalyst for the hydrogenation of maleic anhydride to succinic anhydride includes the following steps: S1. Immerse activated carbon in a phosphoric acid solution with a mass concentration of 80%. Stir evenly at a stirring speed of 110 r / min every 10 min for 1.5 min. After soaking for 1.1 h, filter to obtain acid-soaked activated carbon.

[0045] S2. Take 50 g of the acid-soaked activated carbon obtained in S1, disperse it in 480 mL of water, add 0.7 g of γ-glycidoxypropyltrimethoxysilane and 10 g of NiCl2·6H2O under stirring at 160 r / min, and continuously stir for 11 min to obtain a mixed solution.

[0046] S3. Add an aqueous sodium hydroxide solution with a mass fraction of 0.6% to the mixed solution obtained in S2 until the pH reaches 10. Continue stirring for 5.8 h, then filter and wash with water until neutral and no Cl can be detected. - Then, under vacuum drying at 60 °C for 11 h, the catalyst for the hydrogenation of maleic anhydride to succinic anhydride is obtained.

[0047] Comparative Example 5: The difference between this comparative example and Example 1 is that γ-aminopropyltriethoxysilane is replaced by methyltriethoxysilane.

[0048] Specifically, a preparation method of a catalyst for the hydrogenation of maleic anhydride to succinic anhydride includes the following steps: S1. Immerse activated carbon in a phosphoric acid solution with a mass concentration of 80%. Stir evenly at a stirring speed of 110 r / min every 10 min for 1.5 min. After soaking for 1.1 h, filter to obtain acid-soaked activated carbon.

[0049] S2. Take 50 g of the acid-soaked activated carbon obtained in S1, disperse it in 480 mL of water, add 0.7 g of methyltriethoxysilane and 10 g of NiCl2·6H2O under stirring at 160 r / min, and continuously stir for 11 min to obtain a mixed solution.

[0050] S3. Add an aqueous sodium hydroxide solution with a mass fraction of 0.6% to the mixed solution obtained in S2 until the pH reaches 10. Continue stirring for 5.8 h, then filter and wash with water until neutral and no Cl can be detected. - Then, under vacuum drying at 60 °C for 11 h, the catalyst for the hydrogenation of maleic anhydride to succinic anhydride is obtained.

[0051] Test example: Test object: The catalysts prepared in Examples 1 - 3 and Comparative Examples 1 - 5.

[0052] Test method: Hydrogenation of maleic anhydride to succinic anhydride reaction. Fill 35 g of the catalyst treated by high-temperature reduction activation in a fixed-bed reactor, and introduce a diethylene glycol dimethyl ether solution containing 10 wt% maleic anhydride to carry out the selective hydrogenation reaction of maleic anhydride. The reaction temperature is 80 °C, the reaction pressure is 3 MPa, the reaction time is 3 h, and the mass space velocity of maleic anhydride is 1 h -1 . The molar ratio of hydrogen to maleic anhydride is 30. The conversion rate of maleic anhydride and the selectivity of succinic anhydride are both measured by gas chromatography.

[0053] Test results: See Table 1.

[0054] Table 1. Test data of the test example Result analysis: Analyze Examples 1 - 3 and combine with the data in Table 1 and Figure 1 It can be seen that the catalysts prepared by the present invention (Examples 1 - 3) are used in the process of hydrogenating maleic anhydride to succinic anhydride. The conversion rate of maleic anhydride is as high as over 96.0%, and the selectivity of succinic anhydride is as high as over 98.1%.

[0055] Analyze Example 1 and Comparative Examples 1 - 5 and combine with the data in Table 1 and Figure 1 . By comparing Comparative Example 1 and Comparative Example 2, it can be known that without modification with γ-aminopropyltriethoxysilane, when the concentration of phosphoric acid used for soaking activated carbon is increased from 60% to 80% and the soaking time is extended from 40 min to 1.1 h, the catalytic efficiency of the finally prepared catalyst will decrease. When this catalyst is used in the process of hydrogenating maleic anhydride to succinic anhydride, both the conversion rate of maleic anhydride and the selectivity of succinic anhydride will decrease.

[0056] This is because soaking activated carbon with phosphoric acid can form more micropores and mesopores in the carbon material, increase its specific surface area, improve the dispersion of the catalyst, and thus promote the contact between reactants and active sites, enhancing the catalytic efficiency performance. However, too high a phosphoric acid concentration and too long a soaking time will result in an overly increased specific surface area, which will lead to a decrease in the thermal stability of the material. In this way, during the activation (reduction) treatment of the catalyst, high temperature will cause changes in the structure of activated carbon, reduce the number of active sites, and change the properties of active sites, thereby resulting in a decrease rather than an increase in catalytic efficiency.

[0057] Comparing Comparative Example 1 and Comparative Example 3, it can be seen that when the concentration of phosphoric acid used for soaking activated carbon is 60% and the soaking time is 40 min, adding γ-aminopropyltriethoxysilane for modification has little effect on the catalytic efficiency performance of the finally prepared catalyst.

[0058] Comparing Comparative Example 2 and Example 1, it can be seen that when the concentration of phosphoric acid used for soaking activated carbon is 80% and the soaking time is 1.1 h, adding γ-aminopropyltriethoxysilane for modification can significantly improve the catalytic efficiency performance of the finally prepared catalyst. When this catalyst is used in the process of maleic anhydride hydrogenation to succinic anhydride, both the maleic anhydride conversion rate and the succinic anhydride selectivity are significantly improved.

[0059] This is because the addition of γ-aminopropyltriethoxysilane can effectively modify the structure of activated carbon, thereby enhancing its thermal stability, while maintaining its high specific surface area and rich pore structure to meet the requirements of subsequent applications. Specifically, on the one hand, γ-aminopropyltriethoxysilane contains amino groups, which can react with the functional groups on the surface of activated carbon to form stable chemical bonds, thereby forming a stable siloxane network structure on the surface of activated carbon, modifying the surface of activated carbon 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.

[0060] Comparing Example 1 and Comparative Example 4, it can be seen that when γ-aminopropyltriethoxysilane is replaced by γ-glycidyletheroxypropyltrimethoxysilane, when the prepared catalyst is used in the process of maleic anhydride hydrogenation to succinic anhydride, the maleic anhydride conversion rate and the succinic anhydride selectivity will decrease.

[0061] The inventor believes that this is because γ-glycidyletheroxypropyltrimethoxysilane contains epoxy groups, and its function is similar to the amino group of γ-aminopropyltriethoxysilane. It can react with the functional groups on the surface of activated carbon to form stable chemical bonds, thereby forming a stable siloxane network structure on the surface of activated carbon, modifying the surface of activated carbon and improving its thermal stability. However, γ-glycidyletheroxypropyltrimethoxysilane cannot achieve the nitrogen doping effect brought by γ-aminopropyltriethoxysilane.

[0062] Combined with the comparison of Comparative Example 5, it can be seen that when it is replaced by methyltriethoxysilane, when the prepared catalyst is used in the process of maleic anhydride hydrogenation to succinic anhydride, the maleic anhydride conversion rate and the succinic anhydride selectivity further decrease.

[0063] The inventor believes that this is because methyltriethoxysilane only contains saturated alkyl groups, making it difficult to form chemical bonds with the functional groups on the surface of activated carbon, unable to achieve an effective surface modification effect, and unable to effectively improve the thermal stability of activated carbon.

[0064] In addition, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0065] Furthermore, any combination can be made between various different embodiments of the present invention as long as it does not violate the idea of the present invention, and it should equally be regarded as the content disclosed by the present invention.

Claims

1. A preparation method of a catalyst for hydrogenating maleic anhydride to succinic anhydride, characterized in that, It includes the following steps: S1. Immerse activated carbon into phosphoric acid solution with a mass concentration of 77 - 82%, filter it out after soaking for 1 - 1.2 h to obtain acid - soaked activated carbon; S2. Take 50 g of the acid - soaked activated carbon obtained in S1, disperse it in 460 - 500 mL of water, add 0.5 - 0.8 g of amino - silane coupling agent and 9 - 11 g of NiCl₂·6H₂O under stirring, and continuously stir for 10 - 12 min to obtain a mixed solution; S3. Add an aqueous sodium hydroxide solution to the mixed solution obtained in S2 until the pH reaches 10, continue stirring for 5.5 - 6 h, then filter, wash with water until neutral and no Cl can be detected - and dry to obtain the catalyst for the hydrogenation of maleic anhydride to succinic anhydride. Before use, the catalyst for maleic anhydride hydrogenation to succinic anhydride is subjected to high - temperature reduction activation treatment.

2. The preparation method of the catalyst for maleic anhydride hydrogenation to succinic anhydride according to claim 1, characterized in that The specific operation steps of the high - temperature reduction activation treatment are as follows: Reduce the catalyst for maleic anhydride hydrogenation to succinic anhydride with hydrogen at 120 - 150 °C for 1.8 - 2.3 h, then filter it out, place it in a high - temperature furnace, heat it up and then cool it to room temperature.

3. The preparation method of the catalyst for maleic anhydride hydrogenation to succinic anhydride according to claim 2, characterized in that, The specific heating - up is: Heat up to 460 - 480 °C at a heating rate of 13 - 15 °C / min.

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

5. The preparation method of the catalyst for maleic anhydride hydrogenation to succinic anhydride according to claim 1, characterized in that, In S2, the amino - silane coupling agent is γ - aminopropyltriethoxysilane.

6. The preparation method of the catalyst for maleic anhydride hydrogenation to succinic anhydride according to claim 1, wherein, In S2, the stirring speed is 150 - 180 r / min.

7. The preparation method of the catalyst for maleic anhydride hydrogenation 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%.

8. The preparation method of the catalyst for maleic anhydride hydrogenation to succinic anhydride according to claim 1, characterized in that, In S3, the specific drying operation is: Vacuum - dry at 55 - 65 °C for 10 - 12 h.

9. A catalyst for the hydrogenation of maleic anhydride to succinic anhydride, characterized in that, It is prepared by the preparation method described in any one of claims 1 - 8.

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