A green catalytic synthesis method of succinic anhydride

Abstract

The present invention provides a green catalytic synthesis method for succinic anhydride, comprising the following steps: using a supported nickel carbide-coated nickel nanocomposite as a catalyst and hydrogen as a hydrogen source to catalyze the production of succinic anhydride from maleic anhydride; the supported nickel carbide-coated nickel nanocomposite comprises an activated carbon support, an active metal nickel core, and a nickel carbide shell coated on the surface of the active metal nickel core. Compared to the prior art, the present invention utilizes a specific nickel-based catalyst that achieves high reactivity for maleic anhydride hydrogenation and high selectivity for the single product, succinic anhydride, under relatively mild reaction conditions. The nickel carbide shell protects the nickel nanoparticles within from poisoning, allowing for multiple reuse and reducing catalyst costs. Furthermore, the catalyst is easily separated from the hydrogenation mother liquor after the reaction, allowing for multiple uses without deactivation and exhibiting good stability.

Description

Technical Field

[0001] The present invention relates to the technical field of organic chemical synthesis, and more particularly to a green catalytic synthesis method of succinic anhydride. Background Art

[0002] Succinic anhydride (SA), also known as succinic anhydride, is an extremely important organic synthesis intermediate currently used in a wide range of applications, including the synthesis of food, pharmaceuticals, pesticides, dyes, esters, and resins. It is used in the synthetic resin industry to manufacture alkyd resins and ion exchange resins, and in the pesticide industry to create plant growth regulators. A more important application is the esterification reaction between succinic anhydride's hydrolysis product, succinic acid, and 1,4-butanediol to form the biodegradable plastic polybutylene succinate (PBS). PBS is relatively inexpensive compared to other biodegradable plastics, exhibits excellent heat resistance, and possesses superior mechanical properties, offering broad market prospects. The rapid development of the PBS industry will undoubtedly significantly increase market demand for succinic anhydride. Therefore, the production technology of succinic anhydride has become crucial.

[0003] Currently, the main methods for producing succinic anhydride include paraffin oxidation, biofermentation, and maleic anhydride hydrogenation. Maleic anhydride hydrogenation offers advantages such as simplicity, low energy consumption, and good atom economy. Therefore, developing highly active and selective catalysts for hydrogenating maleic anhydride to produce succinic anhydride has significant social and economic value.

[0004] Catalysts for the catalytic hydrogenation of maleic anhydride are mainly divided into two types: homogeneous catalysts and heterogeneous catalysts. For example, Bai Zhanqi et al. (Study on the homogeneous coordination catalytic hydrogenation of maleic anhydride to succinic anhydride [J] Chemical Reaction Engineering and Technology, 1998, 14(2): 185-189) developed a ruthenium phosphine complex catalyst for maleic anhydride hydrogenation. Under the optimal conditions of 100°C and 3 MPa for 4 h, the maleic anhydride conversion rate was 98.4%, and the succinic anhydride selectivity was 100%. Although homogeneous catalysts exhibit good catalytic effects, due to the use of the precious metal Ru, which is dispersed in the solvent and product during the reaction, it is difficult to separate and reuse after the reaction. Furthermore, the product is easily contaminated with the catalyst, resulting in reduced quality, making it unsuitable for industrial application.

[0005] Heterogeneous catalysts have advantages such as strong designability, clear structure, low price and easy separation from hydrogenation mother liquor, and have greater industrial application prospects. US5952514 uses a catalyst formed by pressing Fe, Co, Ni, C, and Au powders for the preparation of succinic anhydride from maleic anhydride. The reaction is carried out on a fixed bed. Under the conditions of reaction temperature of 60~180℃ and pressure of 38 MPa, the maleic anhydride conversion rate is 99% and the succinic anhydride selectivity is as high as 98%. The disadvantage is that the reaction pressure is too high, resulting in high equipment cost and safety hazards. CN03122336.2 discloses a catalyst with nickel as active component and aluminum oxide and silicon dioxide as carrier for catalytic hydrogenation of maleic anhydride to prepare succinic anhydride. The catalytic hydrogenation reaction is carried out under the conditions of solvent or solvent-free, reaction temperature of 120~180℃, and reaction pressure of 0.5 MPa~3 MPa. Due to the high reaction temperature, the product maleic anhydride undergoes polymerization reaction, resulting in high product chromaticity. CN101502802A discloses a nickel-based catalyst with nickel as the active component, 1% to 7% of a promoter, and alumina, silica, or a composite of the two as a carrier. Maleic anhydride hydrogenation is carried out in a fixed-bed reactor under the conditions of 0.9 MPa to 10 MPa and 60°C to 180°C. The maleic anhydride conversion rate is as high as 99.98% and the succinic anhydride selectivity is greater than 98.85%, but the catalyst is easily poisoned and deactivated. Meyer et al. (Applied Catalysis A: General, 2009, 367(1): 122-129) used 10% Cu / SiO2 to catalyze the hydrogenation of maleic anhydride to succinic anhydride. Under the conditions of a reaction temperature of 220°C and a hydrogen pressure of 1 bar, the selectivity of the product succinic anhydride was as high as 98%. However, the researchers found that after 200 minutes of reaction at 170°C to 220°C, the catalyst had different degrees of deactivation, with the maximum deactivation degree reaching more than 60%.

[0006] Although the above catalysts all show high conversion and selectivity in the reaction of hydrogenating maleic anhydride to produce succinic anhydride, the catalysts used still have disadvantages such as complex preparation process and high price. In addition, the temperature and pressure conditions required for the catalytic reaction are relatively harsh, and the catalysts have poor stability during repeated use. Summary of the Invention

[0007] In view of this, the object of the present invention is to provide a green catalytic synthesis method for succinic anhydride, which can prepare a nickel-based catalyst by a simple and efficient method. The catalyst achieves high reactivity for maleic anhydride hydrogenation and high selectivity for the single product succinic anhydride under relatively mild reaction conditions. After the reaction, the catalyst is easily separated from the hydrogenation mother liquor, can be used multiple times without deactivation, and has good stability.

[0008] The present invention provides a green catalytic synthesis method of succinic anhydride, comprising the following steps:

[0009] The method uses a supported nickel carbide-coated nickel nanocomposite material as a catalyst and hydrogen as a hydrogen source to catalyze maleic anhydride to prepare succinic anhydride. The supported nickel carbide-coated nickel nanocomposite material comprises an activated carbon carrier, an active metal nickel core, and a nickel carbide shell coated on the surface of the active metal nickel core.

[0010] Preferably, the process of catalyzing maleic anhydride to prepare succinic anhydride is specifically as follows:

[0011] The catalyst, maleic anhydride and solvent are added into a high-pressure reactor, and hydrogen is continuously introduced to carry out a hydrogenation reaction to obtain succinic anhydride.

[0012] Preferably, the mass ratio of the catalyst, maleic anhydride and solvent is (0.02-0.2):1:(5-50).

[0013] Preferably, the temperature of the hydrogenation reaction is 80° C. to 120° C., the hydrogen pressure is 0.1 MPa to 5 MPa, and the time is 0.5 h to 12 h.

[0014] Preferably, the solvent is selected from one or more of methanol, ethanol, DMF, DMSO, toluene, n-hexane, acetone, tetrahydrofuran and 1,4-dioxane.

[0015] Preferably, the content of active metal nickel in the supported nickel carbide-coated nickel nanocomposite material is 1 wt% to 40 wt%.

[0016] Preferably, the specific surface area of ​​the activated carbon carrier is 800 m 2 / g~1500 m 2 / g, and the average pore size is 0.5 nm~5 nm.

[0017] Preferably, the active metal nickel core has a face-centered cubic crystal structure.

[0018] Preferably, the preparation method of the supported nickel carbide-coated nickel nanocomposite material is specifically as follows:

[0019] The activated carbon and nickel salt solution are mixed and dried, and then reduced with hydrogen to obtain activated carbon-supported nickel nanoparticles; the surface of the obtained activated carbon-supported nickel nanoparticles is then carbonized using a carbon-containing gas to obtain a supported nickel carbide-coated nickel nanocomposite material.

[0020] Preferably, the temperature of the hydrogen reduction is 350°C to 550°C, and the time is 1 h to 4 h;

[0021] The surface carbonization temperature is 150° C. to 300° C., and the time is 0.5 h to 5 h.

[0022] The present invention provides a green catalytic synthesis method for succinic anhydride, comprising the following steps: using a supported nickel carbide-coated nickel nanocomposite as a catalyst and hydrogen as a hydrogen source to catalyze the production of succinic anhydride from maleic anhydride; the supported nickel carbide-coated nickel nanocomposite comprises an activated carbon support, an active metal nickel core, and a nickel carbide shell coated on the surface of the active metal nickel core. Compared to the prior art, the present invention utilizes a specific nickel-based catalyst that achieves high reactivity for maleic anhydride hydrogenation and high selectivity for the single product, succinic anhydride, under relatively mild reaction conditions. The nickel carbide shell protects the nickel nanoparticles within from poisoning, allowing for multiple reuse and reducing catalyst costs. Furthermore, the catalyst is easily separated from the hydrogenation mother liquor after the reaction, allowing for multiple uses without deactivation and exhibiting good stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 TEM and particle size distribution of catalyst A;

[0024] Figure 2 XRD patterns of activated carbon, catalyst B and catalyst A, among which Ni@NiC x / C is catalyst A, Ni / C is catalyst B, and C is activated carbon;

[0025] Figure 3 The nitrogen adsorption and desorption isotherms of activated carbon, catalyst B and catalyst A are shown in Figure 2. x / C is catalyst A, Ni / C is catalyst B, and C is activated carbon;

[0026] Figure 4 TEM and particle size distribution diagram of catalyst H. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] The present invention provides a green catalytic synthesis method of succinic anhydride, comprising the following steps:

[0029] The method uses a supported nickel carbide-coated nickel nanocomposite material as a catalyst and hydrogen as a hydrogen source to catalyze maleic anhydride to prepare succinic anhydride. The supported nickel carbide-coated nickel nanocomposite material comprises an activated carbon carrier, an active metal nickel core, and a nickel carbide shell coated on the surface of the active metal nickel core.

[0030] The invention provides a method for preparing succinic anhydride by hydrogenating maleic anhydride using a supported nickel carbide-coated nickel nanocomposite material as a catalyst.

[0031] In the present invention, the supported nickel carbide-coated nickel nanocomposite material consists of an activated carbon support, an active metal nickel core, and a nickel carbide shell coated on the surface of the active metal nickel core; the particle size of the active metal nickel core is 5 nm to 15 nm, and the thickness of the nickel carbide shell is 0.1 nm to 10 nm.

[0032] In the present invention, the content of active metal nickel in the supported nickel carbide-coated nickel nanocomposite material is preferably 1 wt% to 40 wt%, more preferably 10 wt% to 40 wt%.

[0033] In the present invention, the specific surface area of ​​the activated carbon carrier is preferably 800 m 2 / g~1500 m 2 / g, and the average pore size is preferably 0.5 nm to 5 nm.

[0034] In the present invention, the active metal nickel core preferably has a face-centered cubic crystal structure.

[0035] In the present invention, the preparation method of the supported nickel carbide-coated nickel nanocomposite material is preferably as follows:

[0036] The activated carbon and nickel salt solution were mixed and dried, and then reduced with hydrogen to obtain activated carbon-supported nickel nanoparticles (denoted as Ni / C). The surface of the obtained activated carbon-supported nickel nanoparticles was then carbonized with a carbon-containing gas to obtain a supported nickel carbide-coated nickel nanocomposite material (denoted as Ni@NiC x / C).

[0037] The present invention has no particular limitation on the sources of the activated carbon and nickel salt solution, and any commercially available products or homemade products known to those skilled in the art may be used.

[0038] The present invention preferably adopts an equal volume impregnation method. First, the saturated adsorption solvent amount of the activated carbon is calculated, and the nickel salt is dispersed in a solvent that can just saturate the activated carbon with adsorption. Ultrasound is preferably used to uniformly disperse it. Then, the prepared nickel salt solution is added dropwise to the activated carbon and continuously stirred to ensure uniform adsorption. Finally, the activated carbon after adsorption is dried.

[0039] In the present invention, the nickel salt is preferably selected from one or more of Ni(acac)2, Ni(CH3COO)2, Ni(NO3)2, NiSO4 and NiCl2; in a preferred embodiment of the present invention, the nickel salt is Ni(NO3)2·6H2O.

[0040] In the present invention, the solvent is preferably selected from one or more of ultrapure water, methanol and ethanol, more preferably ultrapure water.

[0041] In the present invention, the mass ratio of the activated carbon to the solvent is preferably 1:(0.8-2); the concentration of the nickel salt solution is preferably 0.4 mol / L-4 mol / L.

[0042] In the present invention, the drying temperature is preferably 60° C. to 100° C., and the drying time is preferably 0.5 h to 48 h.

[0043] In the present invention, the temperature of the hydrogen reduction is preferably 350° C. to 550° C., more preferably 500° C., and the time is preferably 1 h to 4 h, more preferably 1.5 h.

[0044] In the present invention, the carbon-containing gas is preferably selected from one or more of carbon monoxide, methane, ethylene, and acetylene, and more preferably carbon monoxide, methane, ethylene, or acetylene. The present invention has no particular limitation on the source of the carbon-containing gas, and any commercially available or homemade gas known to those skilled in the art may be used.

[0045] The present invention has no special restrictions on the device for the surface carbonization, and it can be achieved using a tubular furnace familiar to those skilled in the art; first, the air in the tube is exhausted with nitrogen, and then a carbon-containing gas is introduced under high temperature conditions. The gas undergoes a disproportionation reaction on the surface of the nickel metal, causing carbon fragments to enter the nickel lattice, thereby forming a nickel carbide coating on the surface of the nickel nanoparticles.

[0046] In the present invention, the surface carbonization temperature is preferably 150°C to 300°C, more preferably 250°C, and the time is preferably 0.5 h to 5 h, more preferably 1 h. The present invention has no particular limitation on the flow rate of the carbon-containing gas, and a flow rate of 30 mL / min to 100 mL / min well known to those skilled in the art can be used.

[0047] In the present invention, the specific surface area of ​​Ni / C is preferably 100 m 2 / g~300 m 2 / g; the Ni@NiC x / C specific surface area is 150 m 2 / g~250 m 2 / g.

[0048] Ni-based catalysts are widely used in maleic anhydride hydrogenation reactions, but they have the following main problems: the succinic anhydride generated during the reaction forms waxy deposits on the catalyst surface, similar to carbon deposits, which block the active sites of the catalyst. In addition, the active metal itself falls off during stirring, resulting in a low lifespan of traditional nickel-based catalysts used in this reaction. The present invention utilizes a coating strategy to first prepare Ni / C, and then simply treat the Ni / C with a carbon-containing gas such as carbon monoxide. Under high temperature conditions, the carbon-containing gas reacts with Ni to form NiC on the surface of the metal particles. x Species, NiC x The shell effectively prevents the adsorption and aggregation of succinic anhydride, a product of maleic anhydride hydrogenation, on the Ni surface, leading to poisoning and loss of active sites. It also prevents the aggregation and enlargement of metal particles during the reaction. Therefore, this catalyst is suitable for the hydrogenation of maleic anhydride to succinic anhydride.

[0049] In the present invention, the process of catalyzing maleic anhydride to prepare succinic anhydride is preferably as follows:

[0050] The catalyst, maleic anhydride and solvent are added into a high-pressure reactor, and hydrogen is continuously introduced to carry out a hydrogenation reaction to obtain succinic anhydride.

[0051] In the present invention, the catalyst is the supported nickel carbide-coated nickel nanocomposite material described in the above technical solution, which will not be described in detail here.

[0052] The present invention has no particular limitation on the sources of maleic anhydride and hydrogen, and commercially available products or homemade products known to those skilled in the art may be used.

[0053] In the present invention, the solvent is preferably selected from one or more of methanol, ethanol, DMF, DMSO, toluene, n-hexane, acetone, tetrahydrofuran, and 1,4-dioxane, more preferably acetone or 1,4-dioxane. The solvent here is different from the solvent in the nickel salt solution described above and will not be described in detail herein. The source of the solvent is not particularly limited in the present invention; commercially available products known to those skilled in the art may be used.

[0054] In the present invention, the mass ratio of the catalyst, maleic anhydride, and solvent is preferably (0.02-0.2):1:(5-50), more preferably 0.05:1:(5-10).

[0055] In the present invention, before the hydrogenation reaction, the process preferably further comprises: replacing the air in the high-pressure reactor with nitrogen.

[0056] In the present invention, the temperature of the hydrogenation reaction is preferably 80°C to 120°C, more preferably 100°C to 120°C, the hydrogen pressure is preferably 0.1 MPa to 5 MPa, more preferably 2 MPa to 4 MPa, and the time is preferably 0.5 h to 12 h, more preferably 0.5 h to 1 h.

[0057] Compared with the prior art, the present invention has the following technical effects:

[0058] (1) The present invention can obtain a high-yield succinic anhydride product by catalyzing the hydrogenation of maleic anhydride with a catalyst. Under the conditions of a temperature of 100°C, a hydrogen pressure of 3 MPa, and a catalyst to substrate mass ratio of 1:20, the conversion rate of maleic anhydride reaches 100% after 40 minutes of reaction, and the selectivity of succinic anhydride is higher than 99%. The surface shell weakens the adsorption of the product, making the structure of the catalyst more stable, and the catalyst can be reused 8 times without deactivation. Compared with the homogeneous catalytic system, the process of the present invention is simple, and the catalyst can be reused by filtering, washing, etc. after the reaction. It has high stability and can be reused multiple times without performance degradation.

[0059] (2) Compared with other core-shell nickel-based catalysts, the preparation process of the present invention does not require a large amount of organic matter to coordinate with the nickel precursor, nor does it require high-temperature calcination for molding; the present invention uses carbon-containing gas to disproportionately form carbon fragments and carbon dioxide on the nickel surface, and the carbon fragments enter the nickel lattice to form a shell; the present invention reduces the cost of catalyst preparation and is a green and environmentally friendly catalyst.

[0060] (3) The preparation process of the present invention is simple, the reaction conditions are mild, the product selectivity is high, the separation of the product and the catalyst is relatively simple, and it has universal applicability and can be produced on an industrial scale.

[0061] The present invention provides a green catalytic synthesis method for succinic anhydride, comprising the following steps: using a supported nickel carbide-coated nickel nanocomposite as a catalyst and hydrogen as a hydrogen source to catalyze the production of succinic anhydride from maleic anhydride; the supported nickel carbide-coated nickel nanocomposite comprises an activated carbon support, an active metal nickel core, and a nickel carbide shell coated on the surface of the active metal nickel core; the particle size of the active metal nickel core is 5 nm to 15 nm, and the thickness of the nickel carbide shell is 0.1 nm to 10 nm. Compared with the prior art, the present invention utilizes a specific nickel-based catalyst that achieves high reactivity for maleic anhydride hydrogenation and high selectivity for the single product, succinic anhydride, under relatively mild reaction conditions. The nickel carbide shell protects the internal nickel nanoparticles from poisoning, allowing for multiple reuse and reducing catalyst costs. Furthermore, the catalyst is easily separated from the hydrogenation mother liquor after the reaction, allowing for multiple reuse without deactivation and exhibiting good stability.

[0062] In order to further illustrate the present invention, the following examples are provided for detailed description. The raw materials used in the following examples of the present invention are all commercially available sources, wherein the specific surface area of ​​the activated carbon is 800 m 2 / g~1500 m 2 / g, and the average pore size is 0.5nm~5 nm.

[0063] Example 1: Preparation of catalyst and testing of its catalytic performance

[0064] 1 g of activated carbon and 1.24 g of Ni(NO3)2·6H2O were dissolved in water, mixed evenly and dried for 8 h. 1 g of the dried solid was placed in a porcelain boat and reduced in a hydrogen atmosphere at 500 °C for 90 min. The mixture was cooled by nitrogen. After cooling, a portion of the catalyst was taken out and named B (20 wt% Ni / C). The other portion was further heated to 250 °C and treated with carbon monoxide for 1 h. After cooling, catalyst A (20 wt% Ni@NiC) was obtained. x / C).

[0065] 0.1 g of catalysts A and B were taken respectively, and 2 g of maleic anhydride and 15 mL of acetone were used as solvents. The mixture was placed in the inner lining of a 50 mL autoclave and hydrogenated at a temperature of 100°C and a hydrogen pressure of 3 MPa. The air in the autoclave was replaced with nitrogen before the reaction. The mother liquor was analyzed by gas chromatography and the reacted catalyst was obtained by centrifugal filtration. After drying, the catalyst was applied for research. The reaction conditions were 100°C and 3 MPa. The application results are shown in Tables 1 and 2 below.

[0066] Table 1 Performance evaluation of catalyst A

[0067]

[0068] Table 2 Performance evaluation of catalyst B

[0069]

[0070] The results show that the carbon monoxide-modified Ni-based catalyst prepared in this example has high activity for maleic anhydride hydrogenation. Under the conditions of 100°C and 3 MPa, the reaction is completed in 40 min with a maleic anhydride conversion of 100% and a succinic anhydride selectivity of over 99%. The catalyst has been used eight times without significant deactivation.

[0071] Example 2: Comparison of different carbon-containing gases

[0072] Take 1 g of activated carbon and 1.24 g of Ni(NO3)2·6H2O, dissolve them in water, mix them evenly and dry them for 8 h. Take 1 g of the dried solid and place it in a porcelain boat. Reduce it in a hydrogen atmosphere at 500°C for 90 min, cool it with nitrogen, and then introduce methane, ethylene and acetylene respectively after cooling. Continue to heat it to 250°C and keep it warm for 1 h. After cooling, catalysts C, D and E are obtained.

[0073] 0.1 g of catalysts C, D, and E were taken respectively, and placed in a 50 mL autoclave liner with 2 g of maleic anhydride and 15 mL of acetone as solvent. The hydrogenation reaction was carried out at a temperature of 100°C and a hydrogen pressure of 3 MPa. The air in the autoclave was replaced with nitrogen before the reaction. The mother liquor was analyzed by gas chromatography. The results are shown in Table 3 below.

[0074] Table 3 Performance evaluation of catalysts C, D, and E

[0075]

[0076] Example 3: Comparison of different reaction conditions

[0077] 0.1 g of catalyst A, 2 g of maleic anhydride, and 15 mL of acetone as solvent were respectively placed in the inner lining of a 50 mL autoclave, and hydrogenation reaction was carried out at a given temperature and hydrogen pressure. Before the reaction, the air in the autoclave was replaced with nitrogen, and the mother liquor was analyzed by gas chromatography. The reaction conditions and reaction results are shown in Tables 4 and 5 below.

[0078] Table 4 Performance evaluation of catalyst A at different reaction temperatures

[0079]

[0080] Table 5 Performance evaluation of catalyst A at different reaction pressures

[0081]

[0082] Example 4: Effect of different solvents on hydrogenation reaction

[0083] 0.1 g of catalyst A and 2 g of maleic anhydride were taken, and 15 mL of acetone, 1,4-dioxane, and tetrahydrofuran were used as solvents, respectively. The mixture was placed in the inner lining of a 50 mL high-pressure reactor, and hydrogenation reaction was carried out at a temperature of 100°C and a hydrogen pressure of 3 MPa. Before the reaction, the air in the reactor was replaced with nitrogen. After the reaction, the mother liquor was separated from the catalyst using a suction filtration device. The mother liquor was analyzed by gas chromatography. The results are shown in Table 6 below.

[0084] Table 6 Performance evaluation of catalyst A in different solvents

[0085]

[0086] Example 5: Comparison of catalytic performance of catalysts with different particle sizes

[0087] Take 1 g of activated carbon and 1.24 g of Ni(NO3)2·6H2O and dissolve them in water. Use NaOH solution to adjust the pH value of the above precursor solution to about 8, filter and obtain a solid, and dry the solid for 8 h. Take 1 g of the dried solid and place it in a porcelain boat. Reduce it in a hydrogen atmosphere at 500°C for 90 min, cool it with nitrogen, and then introduce acetylene after cooling. Continue to raise the temperature to 250°C, keep it warm for 1 h, and cool it to obtain catalyst H.

[0088] 0.1 g of catalysts A and H were taken respectively, and placed in the inner lining of a 50 mL autoclave with 2 g of maleic anhydride and 15 mL of acetone as solvent. The hydrogenation reaction was carried out at a temperature of 100°C and a hydrogen pressure of 3 MPa. The air in the autoclave was replaced with nitrogen before the reaction. The mother liquor was analyzed by gas chromatography. The results are shown in Table 7 below.

[0089] Table 7 Performance evaluation of catalysts A and H

[0090]

[0091] The catalyst structure and performance characterization results are shown in Figures 1 to 4 :

[0092] To confirm the catalyst structure, catalyst A was taken for XRD and TEM characterization test. The following conclusions can be drawn from the XRD spectrum: the diffraction peaks at 2θ=44.4°, 51.7°, and 76.2° are attributed to the metal Ni (111), (200), and (220) crystal planes, respectively. Unlike Ni / C, Ni@NiC x / C Due to carbonization of Ni surface, NiC is formed x The shell has diffraction peaks at 2θ=37.8° and 62.3° respectively. x / C TEM image shows that Ni@NiC x The particles are evenly distributed on the carbon support, with uniform size, and most of them are below 10 nm. From the high-magnification electron microscope image, it can be seen that the Ni particles are surrounded by a coating layer with a thickness of about 1 nm, which is determined to be NiC x .

[0093] Catalysts A and B and the activated carbon carrier were used for nitrogen isothermal adsorption and desorption experiments. The nitrogen adsorption and desorption isotherms were obtained by the volume method, the surface area of ​​the samples was calculated by the BET method, and the average pore size data was obtained by the Barrett-Joyner-Halenda (BJH) method. The results are shown in Table 8 below.

[0094] Table 8 Evaluation of the structural properties of catalysts A, B and the activated carbon carrier

[0095]

[0096] To confirm the metal content of the catalyst, a small amount of catalyst A was taken into a beaker, concentrated sulfuric acid was added and heated until smoking, and after cooling, perchloric acid and concentrated hydrochloric acid were added, heated to dissolve, and the liquid was taken for inductively coupled plasma mass spectrometry (ICP-MS) analysis, which showed that the nickel ion content (mass fraction) in the liquid was 19.0%.

[0097] Comparative Example 1: Comparison of precious metal catalysts

[0098] 5 wt% Pd / C (named F) and 5 wt% Pt / C (named G) catalysts were purchased from Aladdin Company; 0.2 g of catalysts C and D, 15 g of maleic anhydride, and 150 mL of tetrahydrofuran as solvent were respectively placed in the inner lining of a 500 mL high-pressure reactor, and hydrogenation reaction was carried out at a temperature of 80°C and a hydrogen pressure of 1 MPa. Before the reaction, the air in the reactor was replaced with nitrogen. After the reaction, the mother liquor was separated from the catalyst using a suction filtration device, the catalyst was dried for use, and the mother liquor was analyzed by gas chromatography. The results are shown in Table 9 below.

[0099] Table 9 Performance evaluation of catalysts F and G

[0100]

[0101] Experimental results show that precious metals such as Pd and Pt not only have the ability to activate C=C double bonds, but also hydrogenate C=O bonds to produce by-products.

[0102] Comparative Example 2: Comparison with commercial Raney nickel catalyst

[0103] 0.1 g of commercial Raney nickel catalyst, 2 g of maleic anhydride, and 15 mL of acetone as solvent were placed in a 50 mL autoclave liner and hydrogenated at 100°C and 3 MPa of hydrogen. Before the reaction, the air in the autoclave was replaced with nitrogen. The mother liquor was analyzed by gas chromatography and the reacted catalyst was obtained by centrifugal filtration. After drying, it was applied to the research. The reaction conditions were 100°C and 3 MPa. The application results are shown in Table 10 below.

[0104] Table 10 Performance evaluation of commercial Raney nickel catalyst

[0105]

[0106] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A green catalytic synthesis method of succinic anhydride, characterized in that: The following steps are involved: The method uses a supported nickel carbide-coated nickel nanocomposite material as a catalyst and hydrogen as a hydrogen source to catalyze maleic anhydride to prepare succinic anhydride. The supported nickel carbide-coated nickel nanocomposite material comprises an activated carbon carrier, an active metal nickel core, and a nickel carbide shell coated on the surface of the active metal nickel core.

2. The green catalytic synthesis method of succinic anhydride according to claim 1, characterized in that: The process of preparing succinic anhydride by catalyzing maleic anhydride is specifically as follows: The catalyst, maleic anhydride and solvent are added into a high-pressure reactor, and hydrogen is continuously introduced to carry out a hydrogenation reaction to obtain succinic anhydride.

3. The green catalytic synthesis method of succinic anhydride according to claim 2, characterized in that, The mass ratio of the catalyst, maleic anhydride and solvent is (0.02-0.2):1:(5-50).

4. The green catalytic synthesis method of succinic anhydride according to claim 2, characterized in that: The hydrogenation reaction temperature is 80° C. to 120° C., the hydrogen pressure is 0.1 MPa to 5 MPa, and the reaction time is 0.5 h to 12 h.

5. The green catalytic synthesis method of succinic anhydride according to claim 2, characterized in that: The solvent is selected from one or more of methanol, ethanol, DMF, DMSO, toluene, n-hexane, acetone, tetrahydrofuran and 1,4-dioxane.

6. The green catalytic synthesis method of succinic anhydride according to claim 1, characterized in that: The content of active metal nickel in the supported nickel carbide-coated nickel nanocomposite material is 1 wt% to 40 wt%.

7. The green catalytic synthesis method of succinic anhydride according to claim 1, characterized in that: The specific surface area of ​​the activated carbon carrier is 800 m 2 / g~1500 m 2 / g, and the average pore size is 0.5 nm~5 nm.

8. The green catalytic synthesis method of succinic anhydride according to claim 1, characterized in that: The active metal nickel core has a face-centered cubic crystal structure.

9. The green catalytic synthesis method of succinic anhydride according to claim 1, characterized in that: The preparation method of the supported nickel carbide-coated nickel nanocomposite material is specifically as follows: The activated carbon and nickel salt solution are mixed and dried, and then reduced with hydrogen to obtain activated carbon-supported nickel nanoparticles; the surface of the obtained activated carbon-supported nickel nanoparticles is then carbonized using a carbon-containing gas to obtain a supported nickel carbide-coated nickel nanocomposite material.

10. The green catalytic synthesis method of succinic anhydride according to claim 9, characterized in that: The temperature of the hydrogen reduction is 350°C to 550°C, and the time is 1 h to 4 h; The surface carbonization temperature is 150° C. to 300° C., and the time is 0.5 h to 5 h.

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