Pyromellitic dianhydride catalyst and preparation method thereof

Abstract

The present invention relates to a pyromellitic dianhydride catalyst and a preparation method thereof, and belongs to the technical field of catalyst production, the pyromellitic dianhydride catalyst comprises an inert carrier, and an upper layer catalyst A and a lower layer catalyst B respectively coating the surface of the inert carrier, the upper-layer catalyst A is prepared from the following raw materials in parts by weight: 0.5 to 1 part of vanadium pentoxide nanowire, 2 to 3 parts of composite nano titanium dioxide, 2.5 to 3.5 parts of modified adhesive, 0.04 to 0.08 part of additive and 10 to 15 parts of deionized water; the lower-layer catalyst B is prepared from the following raw materials in parts by weight: 0.5 to 1 part of vanadium pentoxide nanowire, 2 to 3 parts of composite nano titanium dioxide, 2.5 to 3.5 parts of modified adhesive, 0.06 to 0.1 part of additive and 10 to 15 parts of deionized water; according to the technical scheme, the reinforcing material is combined with the silane coupling agent to obtain the silane reinforcing material; a silane reinforcing material is combined with the composite binder, and a modified binder is obtained; and the catalytic activity of the catalyst is well improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst production. Specifically, it relates to a pyromellitic dianhydride catalyst and a preparation method thereof. Background Art

[0002] Pyromellitic dianhydride (referred to as pyromellitic dianhydride for short) is an important chemical raw material, which is mainly used for synthesizing polyimide, curing and matting agent of epoxy resin, cross-linking agent of polyester resin, etc. The products made of pyromellitic dianhydride can be widely used in cutting-edge technology fields such as aerospace, electronic industry, and high-performance composite materials. In the synthesis process of pyromellitic dianhydride, the performance of the catalyst largely determines the yield, selectivity, and purity of the product. At present, the commonly used preparation processes for preparing pyromellitic dianhydride catalysts include spraying method, impregnation method, sol-gel method, etc. Among them, the spraying method is widely used because of its simple operation, uniform coating, and suitability for continuous production. This preparation method usually mixes each component in a predetermined ratio to form a suspension for standby, then sprays the suspension onto the surface of the carrier with a spray gun to form an active coating with a certain thickness, and finally calcines and activates the catalyst to obtain a pyromellitic dianhydride catalyst with excellent catalytic performance. Although the process for preparing pyromellitic dianhydride catalyst by spraying method has been relatively mature, there are still some deficiencies in actual application. Therefore, it is necessary to further improve the comprehensive performance of pyromellitic dianhydride catalyst.

[0003] In the prior art, when preparing pyromellitic dianhydride catalyst by spraying method, due to the uneven distribution of its active components (such as vanadium pentoxide, metal oxides, etc.) on the surface of the carrier, it will cause too high or too low activity in some areas, affecting the catalytic efficiency and selectivity of the catalyst, and the contact efficiency between the reactants and the active sites decreases, resulting in a decrease in the yield of pyromellitic dianhydride; in addition, the phenomenon of coating peeling is likely to occur during the preparation process. Usually, a high-strength binder (such as polyvinyl acetate) is used to enhance the adhesion of the coating on the carrier. However, these binders will lose their binding effect due to decomposition during calcination and activation, resulting in a weak interfacial binding force between the active components and the carrier, being easily peeled off at high temperature, and also causing a decrease in the mechanical strength of the catalyst, affecting the service life of the catalyst. Summary of the Invention

[0004] The object of the present invention is to provide a phthalic anhydride catalyst and a preparation method thereof. An enhanced material is prepared by loading metal oxides with nano-enhancing fillers; a silane-enhanced material is obtained by combining the enhanced material with a silane coupling agent; the silane-enhanced material in step S1 is combined with a composite binder to obtain a modified binder; vanadium pentoxide nanowires, composite nano-titanium dioxide, the modified binder, additives and deionized water are mixed, and after ball milling, they are respectively coated on an inert carrier to obtain an upper-layer catalyst A and a lower-layer catalyst B, which are packaged separately, and finally a phthalic anhydride catalyst is obtained; the modified binder can effectively improve the catalytic performance, thermal stability and mechanical strength of the catalyst, enhance the adhesion of the coating on the carrier, improve the interfacial bonding force between the active component and the carrier, increase the phthalic anhydride yield, extend the service life of the catalyst, and overall improve the comprehensive performance of the phthalic anhydride catalyst.

[0005] The technical problem to be solved by the present invention: In the prior art, when preparing a phthalic anhydride catalyst by the spraying method, since the active components (such as vanadium pentoxide, metal oxides, etc.) are unevenly distributed on the surface of the carrier, it will cause too high or too low activity in some areas, affecting the catalytic efficiency and selectivity of the catalyst, and the contact efficiency between the reactants and the active sites decreases, resulting in a reduction in the phthalic anhydride yield; in addition, the phenomenon of coating peeling easily occurs during the preparation process. Usually, a high-strength binder (such as polyvinyl acetate) is used to enhance the adhesion of the coating on the carrier, but these binders will lose their bonding effect due to decomposition during calcination activation, resulting in a weak interfacial bonding force between the active component and the carrier, being easily peeled off at high temperatures, and causing a decrease in the mechanical strength of the catalyst, affecting the service life of the catalyst.

[0006] The object of the present invention can be achieved by the following technical solutions: A phthalic anhydride catalyst, comprising an inert carrier and an upper-layer catalyst A and a lower-layer catalyst B respectively coated on the surface of the inert carrier; The upper-layer catalyst A comprises the following raw materials in parts by weight: 0.5 - 1 part of vanadium pentoxide nanowires, 2 - 3 parts of composite nano-titanium dioxide, 2.5 - 3.5 parts of modified binder, 0.04 - 0.08 part of additives and 10 - 15 parts of deionized water; The lower-layer catalyst B comprises the following raw materials in parts by weight: 0.5 - 1 part of vanadium pentoxide nanowires, 2 - 3 parts of composite nano-titanium dioxide, 2.5 - 3.5 parts of modified binder, 0.06 - 0.1 part of additives and 10 - 15 parts of deionized water; The preparation method of the modified binder comprises the following steps: S1: A silane-enhanced material is obtained by combining an enhanced material with a silane coupling agent; S2: The silane-enhanced material in step S1 is combined with a composite binder to obtain a modified binder; The reinforcing material is prepared by loading metal oxides with nano-reinforcing fillers.

[0007] Further, step S1 is specifically as follows: Add the reinforcing material and the silane coupling agent to a mixed solution of ethanol and water, then perform ultrasonic treatment for 25 - 35 min, then stir at 55 - 65 °C for 22 - 24 h, filter, wash with ethanol, and finally perform vacuum drying at 55 - 65 °C to obtain the silane-reinforced material.

[0008] During the above reaction process, the surface of the reinforcing material has hydroxyl groups. After the silane coupling agent hydrolyzes, silanol groups can be generated. The silanol groups on the silane coupling agent can combine with the hydroxyl groups on the reinforcing material to graft the silane coupling agent onto the surface of the reinforcing material, and finally the silane-reinforced material is obtained.

[0009] Further, the mass ratio of the reinforcing material, the silane coupling agent, and the mixed solution of ethanol and water is 4.8 - 5.2 : 0.8 - 1.2 : 80 - 90.

[0010] Further, the silane coupling agent is 3-glycidoxypropyltriethoxysilane.

[0011] Further, the preparation method of the reinforcing material includes the following steps: Add the nano-reinforcing filler to deionized water, and treat it in an ultrasonic bath for 1.5 - 2.5 h, then add the metal oxide, and continue to treat it in the ultrasonic bath for 1.5 - 2.5 h. After completion, stir at 25 - 35 °C for 1.5 - 2.5 h, and finally perform vacuum drying at 90 - 100 °C to obtain the reinforcing material.

[0012] During the above reaction process, the metal oxide can be loaded on the surface of the nano-reinforcing filler through hydrogen bond interaction, thereby combining the nano-reinforcing filler and the metal oxide together, and finally obtaining the reinforcing material.

[0013] Further, the mass ratio of the nano-reinforcing filler, deionized water, and the metal oxide is 0.8 - 1.2 : 50 - 60 : 0.05 - 0.15.

[0014] Further, the nano-reinforcing filler is composed of graphene oxide and halloysite nanotubes mixed in a mass ratio of 0.8 - 0.9 : 0.5 - 0.6.

[0015] Further, the metal oxide is composed of nano-molybdenum oxide, nano-cerium oxide, and nano-manganese dioxide mixed in a mass ratio of 0.7 - 0.8 : 0.3 - 0.4 : 0.1 - 0.2.

[0016] Further, step S2 is specifically as follows: Add the composite binder to deionized water, stir at 85 - 95 °C for 1.5 - 2.5 h, then add the silane reinforcing material in step S1, and stir at 85 - 95 °C for 0.5 - 1.5 h to obtain a gel-like solution. Continue to stir the gel-like solution at 85 - 95 °C for 5.5 - 6.5 h. After completion, cool to room temperature, filter, and finally dry at room temperature to obtain the modified binder.

[0017] During the above reaction process, the composite binder has hydroxyl groups, and the silane coupling agent on the silane reinforcing material has epoxy groups. The hydroxyl groups on the composite binder can combine with the epoxy groups on the silane reinforcing material through ring-opening reaction, binding the composite binder and the silane reinforcing material together, and finally obtaining the modified binder.

[0018] Further, the mass ratio of the composite binder, deionized water, and silane reinforcing material is 9.8 - 10.2:100 - 120:0.4 - 0.6.

[0019] Further, the composite binder is composed of polyvinyl alcohol and lignin amino polyol mixed in a mass ratio of 0.6 - 0.7:0.4 - 0.5.

[0020] Further, the preparation method of the lignin amino polyol includes the following steps: Mix alkali lignin, deionized water, diethanolamine, and diisopropanolamine evenly, then heat to 75 - 85 °C, add formaldehyde solution, adjust the pH value of the system to 11.5 - 12.5 with sodium hydroxide solution, then stir and react for 1.5 - 2.5 h. After the reaction is completed, precipitate with sulfuric acid solution, filter, wash with deionized water, and finally vacuum dry at 45 - 55 °C to obtain lignin amino polyol.

[0021] During the above reaction process, alkali lignin has phenolic hydroxyl groups, and there are active hydrogen atoms on the ortho-carbon atoms of the phenolic hydroxyl groups. Both diethanolamine and diisopropanolamine have amino groups. The amino groups in diethanolamine and diisopropanolamine can carry out Mannich reaction with the active hydrogen atoms in alkali lignin in the presence of formaldehyde, binding alkali lignin with diethanolamine and diisopropanolamine together, and finally obtaining lignin amino polyol.

[0022] Further, the mass ratio of the alkali lignin, deionized water, diethanolamine, and diisopropanolamine is 2.8 - 3.2:10 - 15:3.8 - 4.2:1.8 - 2.2.

[0023] A preparation method of a phthalic anhydride catalyst includes the following steps: A1: Prepare the upper catalyst A: Weigh the raw materials in parts by mass. Mix vanadium pentoxide nanowires, composite nano-titanium dioxide, an auxiliary agent, and deionized water, and then perform ball milling. After the ball milling is completed, add a modified binder and stir for 5 - 10 min to obtain the upper active component A. Weigh an inert carrier and place it in a rotating drum, then heat it to 75 - 85 °C, and evenly spray the upper active component A on the surface of the inert carrier. The rotating drum rotates and heats until the coating is completely dried to obtain the upper catalyst A; A2: Preparation of the lower catalyst B: Weigh the raw materials in parts by mass. Mix vanadium pentoxide nanowires, composite nano-titanium dioxide, an auxiliary agent, and deionized water, and then perform ball milling. After the ball milling is completed, add a modified binder and stir at a speed of 300 - 500 rpm for 5 - 10 min to obtain the lower active component B. Weigh an inert carrier and place it in a rotating drum, then heat it to 75 - 85 °C, and evenly spray the lower active component B on the surface of the inert carrier. The rotating drum rotates and heats until the coating is completely dried to obtain the lower catalyst B; A3: Packaging: Package the upper catalyst A in step A1 and the lower catalyst B in step A2, and finally obtain the phthalic anhydride catalyst.

[0024] Furthermore, the composite nano-titanium dioxide is composed of anatase nano-titanium dioxide and rutile nano-titanium dioxide mixed in a mass ratio of 4 - 5:1.

[0025] Furthermore, the auxiliary agent is lanthanum oxide.

[0026] Furthermore, the ball milling time is 6 - 7 h, and the ball milling speed is 300 - 400 rpm.

[0027] Furthermore, the inert carrier is a hollow cylindrical porcelain ring with a specification of outer diameter × height × thickness: 7.5 mm × 6 mm × 2 mm.

[0028] Furthermore, the preparation method of the vanadium pentoxide nanowires includes the following steps: Add vanadium pentoxide to deionized water, then add hydrogen peroxide solution, and stir for 2 h. Then add sodium citrate, stir evenly, transfer to a Teflon-lined stainless steel autoclave, and maintain at 180 °C for 24 h. Cool to room temperature, wash 3 times with ethanol, then dry at 60 °C for 24 h, and then place in a muffle furnace and sinter in air at 300 °C for 2 h. Finally, obtain vanadium pentoxide nanowires.

[0029] Furthermore, the mass ratio of vanadium pentoxide, deionized water, hydrogen peroxide solution, and sodium citrate is 0.36:30:15:0.23.

[0030] Application of a pyromellitic anhydride catalyst in the reaction of oxidizing 1,2,4,5-tetramethylbenzene to pyromellitic anhydride.

[0031] Advantages of the present invention: (1) In the technical solution of the present invention, a reinforcing material is prepared by loading a metal oxide on a nano-enhancing filler; the nano-enhancing filler is composed of a mixture of graphene oxide and halloysite nanotubes; the mixture of graphene oxide and halloysite nanotubes has a synergistic effect, which can effectively improve the catalytic activity and selectivity of the catalyst. Graphene oxide has a two-dimensional layered structure, providing a large specific surface area, which is beneficial to the uniform dispersion of active components. Halloysite nanotubes have a one-dimensional hollow tubular structure, providing more acidic sites, which is beneficial to improving the catalytic activity of the catalyst. Mixing graphene oxide and halloysite nanotubes can form a three-dimensional network structure, which not only helps the highly dispersed active components, provides more contact sites for reactants, but also enhances the mechanical strength and thermal stability of the pyromellitic anhydride catalyst, and can better load the metal oxide, increase its dispersion, and improve the binding between the nano-enhancing filler and the metal oxide; the metal oxide is composed of a mixture of nano-molybdenum oxide, nano-cerium oxide and nano-manganese dioxide; the three have a synergistic effect, which can better improve the catalytic activity and selectivity of the catalyst. Nano-cerium oxide and nano-molybdenum oxide help to control the reaction path, reduce unnecessary side reactions, and improve the selectivity of the catalyst. Nano-manganese dioxide can further improve the catalytic activity. The mixture of the three is beneficial to improving the catalytic efficiency of the catalyst, increasing the pyromellitic anhydride yield, and enhancing the thermal stability and mechanical strength of the catalyst; by combining the reinforcing material with a silane coupling agent, a silane-reinforced material is obtained; the silane coupling agent is grafted on the surface of the reinforcing material, which can better improve the dispersion of the reinforcing material, prevent its agglomeration, and provide reaction sites for subsequent reactions, further increasing the adhesion of the coating on the carrier, which is beneficial to improving the catalytic efficiency of the catalyst.

[0032] (2)In the technical solution of the present invention, by combining a silane reinforcing material with a composite binder, a modified binder is obtained; the composite binder is composed of a mixture of polyvinyl alcohol and lignin aminated polyol; the two have a synergistic effect and have good bonding performance, which helps to improve the adhesion of the coating on the carrier. Polyvinyl alcohol has good thermal stability and can maintain its structural integrity at high temperatures. Moreover, polyvinyl alcohol is a water-soluble polymer with good environmental friendliness. Lignin aminated polyol also has good thermal stability and helps to improve the catalytic efficiency of the catalyst. When polyvinyl alcohol and lignin aminated polyol are mixed, they have good binding force with the silane reinforcing material, which can further improve the mechanical strength and thermal stability of the catalyst, and can better improve the catalytic activity and selectivity of the catalyst, increase the phthalic anhydride yield, and extend the service life of the catalyst; vanadium pentoxide nanowires, composite nano-titanium dioxide, modified binder, additives and deionized water are mixed, and after ball milling, they are respectively coated on an inert carrier to obtain an upper-layer catalyst A and a lower-layer catalyst B, which are packaged separately, and finally a phthalic anhydride catalyst is obtained; the modified binder effectively improves the overall comprehensive performance of the phthalic anhydride catalyst, increases the phthalic anhydride yield, and the catalytic performance of the catalyst and the phthalic anhydride yield are significantly improved compared with the products of the same period on the market.

[0033] (3)In the technical solution of the present invention, a reinforcing material is prepared by loading a metal oxide with a nano-reinforcing filler, then the reinforcing material is combined with a silane coupling agent and then with a composite binder to obtain a modified binder; vanadium pentoxide nanowires, composite nano-titanium dioxide, modified binder, additives and deionized water are mixed, and after ball milling, they are respectively coated on an inert carrier, and finally a phthalic anhydride catalyst is obtained; the catalytic performance, thermal stability and mechanical strength of the phthalic anhydride catalyst are overall improved, the adhesion of the coating on the inert carrier is enhanced, the phthalic anhydride yield is increased, the service life of the phthalic anhydride catalyst is extended, the environmental friendliness is good, and the overall comprehensive performance is good. Specific embodiments

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0035] The specific parameters of the raw materials used in the present invention are as follows: 3-Glycidoxypropyltriethoxysilane, CAS No.: 2602-34-8, Product No.: G832117, provided by Shanghai Macklin Biochemical Co., Ltd.; Graphene oxide, No.: XF002-2, provided by Jiangsu Xianfeng Nano Materials Technology Co., Ltd.; Halloysite nanotubes, provided by Angxing New Carbon Materials Changzhou Co., Ltd.; Nano molybdenum oxide, Article No.: JL-MoO3-N20, provided by Ningbo Jinlei Nano Materials Technology Co., Ltd.; Nano cerium oxide, particle size of 30 nm and purity of 99.99%, provided by Ningbo Luofei Nano Technology Co., Ltd.; Nano manganese dioxide, particle size / mesh number: 500 mesh, provided by Dinghong (Shanghai) New Materials Technology Co., Ltd.; Polyvinyl alcohol, CAS No.: 9002-89-5, Product No.: P752227, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.; Alkali lignin, CAS: 8068-05-1, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.; Vanadium pentoxide, CAS No.: 1314-62-1, Product No.: V838365, provided by Shanghai Macklin Biochemical Co., Ltd.; Anatase nano titanium dioxide, model: VK-TA18, particle size: 20 nm, provided by Xuancheng Jingrui New Materials Co., Ltd.; Rutile nano titanium dioxide, provided by Qinghe County Ruijiang Metal Materials Co., Ltd.

[0036] The preparation method of vanadium pentoxide nanowires comprises the following steps: According to the mass ratio of vanadium pentoxide, deionized water, hydrogen peroxide solution, and disodium citrate of 0.36:30:15:0.23, add vanadium pentoxide to deionized water, then add 30 wt% hydrogen peroxide solution, and stir for 2 h. Then add disodium citrate, stir evenly, transfer to a 100 mL Teflon-lined stainless steel autoclave, and maintain at 180 °C for 24 h. Cool to room temperature, wash with ethanol 3 times (each time the mass of ethanol is 40% of the mass of deionized water), then dry at 60 °C for 24 h, and then place in a muffle furnace and sinter in air at 300 °C for 2 h to finally obtain vanadium pentoxide nanowires.

[0037] Example 1 Prepare a modified adhesive, and the specific steps are as follows: S1: According to the mass ratio of reinforcing material, 3-glycidoxypropyltriethoxysilane, ethanol, and water mixed solution of 4.8:0.8:80, add the reinforcing material and 3-glycidoxypropyltriethoxysilane to the ethanol and water mixed solution (the volume ratio of ethanol and water is 9:1), then perform ultrasonic treatment for 25 min (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), and then stir at 55 °C for 24 h. After filtration, wash with ethanol 3 times (each time the mass of ethanol is 20% of the mass of the ethanol and water mixed solution), and finally vacuum dry at 55 °C for 48 h to obtain a silane-reinforced material; The preparation method of the reinforcing material comprises the following steps: According to the mass ratio of nano-reinforcing filler, deionized water, and metal oxide being 0.8:50:0.05, add the nano-reinforcing filler into deionized water, and treat it in an ultrasonic bath for 1.5 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then add the metal oxide, and continue to treat it in the ultrasonic bath for 1.5 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz). After completion, stir at 25 °C for 2.5 h, and finally vacuum dry at 90 °C for 24 h to obtain the reinforcing material. Among them, the nano-reinforcing filler is composed of graphene oxide and halloysite nanotubes mixed according to a mass ratio of 0.8:0.5; the metal oxide is composed of nano-molybdenum oxide, nano-cerium oxide, and nano-manganese dioxide mixed according to a mass ratio of 0.7:0.3:0.1; S2: According to the mass ratio of composite binder, deionized water, and silane reinforcing material being 9.8:100:0.4, add the composite binder into deionized water, and stir at 85 °C for 2.5 h, then add the silane reinforcing material in step S1, and stir at 85 °C for 1.5 h to obtain a gel-like solution. Continue to stir the gel-like solution at 85 °C for 6.5 h. After completion, cool to room temperature, filter, and finally dry at room temperature for 24 h to obtain the modified adhesive. Among them, the composite binder is composed of polyvinyl alcohol and lignin aminated polyol mixed according to a mass ratio of 0.6:0.4; The preparation method of lignin aminated polyol comprises the following steps: According to the mass ratio of alkali lignin, deionized water, diethanolamine, and diisopropanolamine being 2.8:10:3.8:1.8, mix alkali lignin, deionized water, diethanolamine, and diisopropanolamine evenly, then heat to 75 °C, and then add 37 wt% formaldehyde solution (the mass of the formaldehyde solution is 1.2 times the mass of alkali lignin). Adjust the pH value of the system to 11.5 with 1 mol / L sodium hydroxide solution, then stir and react for 1.5 h. After the reaction is completed, precipitate with 10 wt% sulfuric acid solution (the mass of the sulfuric acid solution is equal to the mass of deionized water), filter, wash with deionized water 3 times (the mass of deionized water each time is 1.5 times the mass of the above deionized water), and finally vacuum dry at 45 °C for 24 h to obtain lignin aminated polyol; A phthalic anhydride catalyst comprises an inert carrier and an upper catalyst A and a lower catalyst B respectively coated on the surface of the inert carrier; The upper catalyst A comprises the following raw materials in parts by weight: 0.5 part of vanadium pentoxide nanowires, 2 parts of composite nano-titanium dioxide, 2.5 parts of modified adhesive, 0.04 part of lanthanum oxide, and 10 parts of deionized water; The lower-layer catalyst B comprises the following raw materials in parts by weight: 0.5 part of vanadium pentoxide nanowires, 2 parts of composite nano-titanium dioxide, 2.5 parts of modified binder, 0.06 part of lanthanum oxide, and 10 parts of deionized water; Among them, the composite nano-titanium dioxide is composed of anatase nano-titanium dioxide and rutile nano-titanium dioxide mixed in a mass ratio of 4:1; The inert carrier is a hollow cylindrical porcelain ring, and its specifications are outer diameter × height × thickness: 7.5 mm × 6 mm × 2 mm; A1: Preparation of the upper-layer catalyst A: Weigh the raw materials in parts by weight. Mix the vanadium pentoxide nanowires, composite nano-titanium dioxide, lanthanum oxide, and deionized water, and then carry out ball milling. The ball milling time is 6 h, the ball milling speed is 400 rpm, use zirconia balls as the grinding spheres, and the mass of the grinding spheres is 8 times the mass of the composite nano-titanium dioxide (i.e., the ball-to-material ratio is 8:1). After the ball milling is completed, add the modified binder and stir at a speed of 300 rpm for 10 min to obtain the upper-layer active component A. Weigh the inert carrier and put it into a rotating drum (the mass of the inert carrier accounts for 37.5% of the production capacity of the rotating drum), and then heat it to 75 °C. Spray the upper-layer active component A evenly on the surface of the inert carrier. The rotating drum rotates and heats at the same time (the rotation rate of the rotating drum is 30 rpm) until the coating is completely dried to obtain the upper-layer catalyst A; A2: Preparation of the lower-layer catalyst B: Weigh the raw materials in parts by weight. Mix the vanadium pentoxide nanowires, composite nano-titanium dioxide, lanthanum oxide, and deionized water, and then carry out ball milling. The ball milling time is 6 h, the ball milling speed is 400 rpm, use zirconia balls as the grinding spheres, and the mass of the grinding spheres is 8 times the mass of the composite nano-titanium dioxide (i.e., the ball-to-material ratio is 8:1). After the ball milling is completed, add the modified binder and stir at a speed of 300 rpm for 10 min to obtain the lower-layer active component B. Weigh the inert carrier and put it into a rotating drum (the mass of the inert carrier accounts for 37.5% of the production capacity of the rotating drum), and then heat it to 75 °C. Spray the lower-layer active component B evenly on the surface of the inert carrier. The rotating drum rotates and heats at the same time (the rotation rate of the rotating drum is 30 rpm) until the coating is completely dried to obtain the lower-layer catalyst B; A3: Packaging: Package the upper-layer catalyst A in step A1 and the lower-layer catalyst B in step A2 to finally obtain the phthalic anhydride catalyst.

[0038] Example 2 Prepare the modified binder, and the specific steps are as follows: S1: According to the mass ratio of the reinforcing material, 3-glycidoxypropyltriethoxysilane, ethanol and water mixed solution being 5:1:85, add the reinforcing material and 3-glycidoxypropyltriethoxysilane into the ethanol and water mixed solution (the volume ratio of ethanol and water is 9:1), then perform ultrasonic treatment for 30 min (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then stir at 60 °C for 23 h, filter, wash with ethanol 3 times (the mass of ethanol each time is 20% of the mass of the ethanol and water mixed solution), and finally vacuum dry at 60 °C for 48 h to obtain the silane reinforcing material; The preparation method of the reinforcing material includes the following steps: According to the mass ratio of the nano-reinforcing filler, deionized water, and metal oxide being 1:55:0.1, add the nano-reinforcing filler into deionized water and treat it in an ultrasonic bath for 2 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then add the metal oxide and continue to treat it in the ultrasonic bath for 2 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz). After completion, stir at 30 °C for 2 h, and finally vacuum dry at 95 °C for 24 h to obtain the reinforcing material, where the nano-reinforcing filler is composed of graphene oxide and halloysite nanotubes mixed according to the mass ratio of 0.85:0.55; the metal oxide is composed of nano-molybdenum oxide, nano-cerium oxide, and nano-manganese dioxide mixed according to the mass ratio of 0.75:0.35:0.15; S2: According to the mass ratio of the composite binder, deionized water, and silane reinforcing material being 10:110:0.5, add the composite binder into deionized water and stir at 90 °C for 2 h, then add the silane reinforcing material in step S1 and stir at 90 °C for 1 h to obtain a gel-like solution. Continue to stir the gel-like solution at 90 °C for 6 h. After completion, cool to room temperature, filter, and finally dry at room temperature for 24 h to obtain the modified binder, where the composite binder is composed of polyvinyl alcohol and lignin aminated polyol mixed according to the mass ratio of 0.65:0.45; The preparation method of the lignin aminated polyol includes the following steps: According to the mass ratio of alkali lignin, deionized water, diethanolamine, and diisopropanolamine being 3:12:4:2, mix alkali lignin, deionized water, diethanolamine, and diisopropanolamine evenly, then heat to 80 °C, and then add 37 wt% formaldehyde solution (the mass of the formaldehyde solution is 1.2 times the mass of alkali lignin), adjust the pH value of the system to 12 with 1 mol / L sodium hydroxide solution, then stir and react for 2 h. After the reaction is completed, precipitate with 10 wt% sulfuric acid solution (the mass of the sulfuric acid solution is equal to the mass of deionized water), filter, wash with deionized water 3 times (the mass of deionized water each time is 1.5 times the mass of the above deionized water), and finally vacuum dry at 50 °C for 24 h to obtain the lignin aminated polyol; A maleic anhydride catalyst includes an inert carrier, and an upper catalyst A and a lower catalyst B respectively coated on the surface of the inert carrier; The upper catalyst A includes the following raw materials in parts by weight: 0.8 part of vanadium pentoxide nanowires, 2.5 parts of composite nano-titanium dioxide, 3 parts of a modified binder, 0.06 part of lanthanum oxide, and 12 parts of deionized water; The lower catalyst B includes the following raw materials in parts by weight: 0.8 part of vanadium pentoxide nanowires, 2.5 parts of composite nano-titanium dioxide, 3 parts of a modified binder, 0.08 part of lanthanum oxide, and 12 parts of deionized water; Among them, the composite nano-titanium dioxide is composed of anatase nano-titanium dioxide and rutile nano-titanium dioxide mixed in a mass ratio of 4.5:1; The inert carrier is a hollow cylindrical porcelain ring, and its specifications are outer diameter × height × thickness: 7.5 mm × 6 mm × 2 mm; A1: Preparation of the upper catalyst A: Weigh the raw materials in parts by weight. Mix the vanadium pentoxide nanowires, composite nano-titanium dioxide, lanthanum oxide, and deionized water, and then carry out ball milling. The ball milling time is 6.5 h, the ball milling speed is 350 rpm, use zirconia balls as the grinding spheres, and the mass of the grinding spheres is 8 times the mass of the composite nano-titanium dioxide (that is, the ball-to-material ratio is 8:1). After the ball milling is completed, add the modified binder and stir at a speed of 400 rpm for 8 min to obtain the upper active component A. Weigh the inert carrier and put it into a rotating drum (the mass of the inert carrier accounts for 37.5% of the production capacity of the rotating drum), then heat to 80 °C, and evenly spray the upper active component A on the surface of the inert carrier. The rotating drum rotates and heats (the rotation rate of the rotating drum is 30 rpm) until the coating is completely dried to obtain the upper catalyst A; A2: Preparation of the lower catalyst B: Weigh the raw materials in parts by weight. Mix the vanadium pentoxide nanowires, composite nano-titanium dioxide, lanthanum oxide, and deionized water, and then carry out ball milling. The ball milling time is 6.5 h, the ball milling speed is 350 rpm, use zirconia balls as the grinding spheres, and the mass of the grinding spheres is 8 times the mass of the composite nano-titanium dioxide (that is, the ball-to-material ratio is 8:1). After the ball milling is completed, add the modified binder and stir at a speed of 400 rpm for 8 min to obtain the lower active component B. Weigh the inert carrier and put it into a rotating drum (the mass of the inert carrier accounts for 37.5% of the production capacity of the rotating drum), then heat to 80 °C, and evenly spray the lower active component B on the surface of the inert carrier. The rotating drum rotates and heats (the rotation rate of the rotating drum is 30 rpm) until the coating is completely dried to obtain the lower catalyst B; A3: Packaging: Package the upper catalyst A in step A1 and the lower catalyst B in step A2, and finally obtain the maleic anhydride catalyst.

[0039] Example 3 Prepare a modified adhesive, and the specific steps are as follows: S1: According to the mass ratio of reinforcing material, 3-glycidoxypropyltriethoxysilane, ethanol and water mixed solution being 5.2:1.2:90, add the reinforcing material and 3-glycidoxypropyltriethoxysilane into the ethanol and water mixed solution (the volume ratio of ethanol to water is 9:1), then perform ultrasonic treatment for 35 min (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then stir at 65 °C for 22 h, filter, wash with ethanol 3 times (the mass of ethanol each time is 20% of the mass of the ethanol and water mixed solution), and finally vacuum dry at 65 °C for 48 h to obtain the silane-reinforced material; The preparation method of the reinforcing material includes the following steps: According to the mass ratio of nano-reinforcing filler, deionized water, and metal oxide being 1.2:60:0.15, add the nano-reinforcing filler into deionized water and treat it in an ultrasonic bath for 2.5 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then add the metal oxide and continue to treat it in the ultrasonic bath for 2.5 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz). After that, stir at 35 °C for 1.5 h, and finally vacuum dry at 100 °C for 24 h to obtain the reinforcing material. Among them, the nano-reinforcing filler is composed of graphene oxide and halloysite nanotubes mixed according to the mass ratio of 0.9:0.6; the metal oxide is composed of nano-molybdenum oxide, nano-cerium oxide, and nano-manganese dioxide mixed according to the mass ratio of 0.8:0.4:0.2; S2: According to the mass ratio of composite binder, deionized water, and silane-reinforced material being 10.2:120:0.6, add the composite binder into deionized water and stir at 95 °C for 1.5 h, then add the silane-reinforced material in step S1 and stir at 95 °C for 0.5 h to obtain a gel-like solution. Keep stirring the gel-like solution at 95 °C for 5.5 h. After that, cool to room temperature, filter, and finally dry at room temperature for 24 h to obtain the modified adhesive. Among them, the composite binder is composed of polyvinyl alcohol and lignin amino-functionalized polyol mixed according to the mass ratio of 0.7:0.5; The preparation method of lignin amino-functionalized polyol includes the following steps: According to the mass ratio of alkali lignin, deionized water, diethanolamine, and diisopropanolamine being 3.2:15:4.2:2.2, mix alkali lignin, deionized water, diethanolamine, and diisopropanolamine evenly, then heat to 85 °C, add a 37 wt% formaldehyde solution (the mass of the formaldehyde solution is 1.2 times the mass of the alkali lignin), adjust the pH value of the system to 12.5 with 1 mol / L sodium hydroxide solution, then stir and react for 2.5 h. After the reaction, precipitate with a 10 wt% sulfuric acid solution (the mass of the sulfuric acid solution is equal to the mass of the deionized water), filter, wash with deionized water 3 times (the mass of deionized water each time is 1.5 times the mass of the above-mentioned deionized water), and finally vacuum dry at 55 °C for 24 h to obtain lignin amino polyol; A phthalic anhydride catalyst includes an inert carrier and upper catalyst A and lower catalyst B respectively coated on the surface of the inert carrier; The upper catalyst A includes the following raw materials in parts by weight: 1 part of vanadium pentoxide nanowires, 3 parts of composite nano-titanium dioxide, 3.5 parts of modified binder, 0.08 part of lanthanum oxide, and 15 parts of deionized water; The lower catalyst B includes the following raw materials in parts by weight: 1 part of vanadium pentoxide nanowires, 3 parts of composite nano-titanium dioxide, 3.5 parts of modified binder, 0.1 part of lanthanum oxide, and 15 parts of deionized water; Among them, the composite nano-titanium dioxide is composed of anatase nano-titanium dioxide and rutile nano-titanium dioxide mixed in a mass ratio of 5:1; The inert carrier is a hollow cylindrical porcelain ring, and its specifications are outer diameter × height × thickness: 7.5 mm × 6 mm × 2 mm; A1: Preparation of upper catalyst A: Weigh the raw materials in parts by weight, mix vanadium pentoxide nanowires, composite nano-titanium dioxide, lanthanum oxide, and deionized water, then carry out ball milling. The ball milling time is 7 h, the ball milling speed is 300 rpm, use zirconia balls as the grinding spheres, and the mass of the grinding spheres is 8 times the mass of the composite nano-titanium dioxide (i.e., the ball-to-material ratio is 8:1). After the ball milling is completed, add the modified binder and stir at a speed of 500 rpm for 5 min to obtain the upper active component A. Weigh the inert carrier and put it into a rotating drum (the mass of the inert carrier accounts for 37.5% of the production capacity of the rotating drum), then heat to 85 °C, and evenly spray the upper active component A on the surface of the inert carrier. The rotating drum rotates and heats while rotating (the rotation rate of the rotating drum is 30 rpm) until the coating is completely dried to obtain the upper catalyst A; A2: Preparation of lower catalyst B: Weigh raw materials in parts by mass. Mix vanadium pentoxide nanowires, composite nano-titanium dioxide, lanthanum oxide and deionized water, and then carry out ball milling. The ball milling time is 7 h, the ball milling speed is 300 rpm, and zirconia balls are used as the grinding spheres. The mass of the grinding spheres is 8 times the mass of the composite nano-titanium dioxide (i.e., the ball-to-material ratio is 8:1). After the ball milling is completed, add a modified binder and stir at a speed of 500 rpm for 5 min to obtain the lower-layer active component B. Weigh the inert carrier and put it into a rotary drum (the mass of the inert carrier accounts for 37.5% of the production capacity of the rotary drum), and then heat it to 85 °C. Spray the lower-layer active component B evenly on the surface of the inert carrier. The rotary drum rotates and heats at the same time (the rotation rate of the rotary drum is 30 rpm) until the coating is completely dried to obtain the lower-layer catalyst B; A3: Sub-packaging: Sub-package the upper-layer catalyst A in step A1 and the lower-layer catalyst B in step A2, and finally obtain the phthalic anhydride catalyst.

[0040] Comparative Example 1 The difference between this comparative example and Example 3 is that when preparing the modified binder, the nano-enhancing filler in step S1 is replaced with graphene oxide in equal mass, and the remaining steps and raw materials are the same as those in Example 3; The preparation method of the reinforcing material includes the following steps: According to the mass ratio of graphene oxide, deionized water, and metal oxide of 1.2:60:0.15, add graphene oxide to deionized water and treat it in an ultrasonic bath for 2.5 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then add the metal oxide and continue to treat it in the ultrasonic bath for 2.5 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz). After completion, stir at 35 °C for 1.5 h, and finally vacuum dry at 100 °C for 24 h to obtain the reinforcing material, where the metal oxide is composed of nano-molybdenum oxide, nano-cerium oxide, and nano-manganese dioxide mixed according to the mass ratio of 0.8:0.4:0.2.

[0041] Comparative Example 2 The difference between this comparative example and Example 3 is that when preparing the modified binder, the nano-enhancing filler in step S1 is replaced with halloysite nanotubes in equal mass, and the remaining steps and raw materials are the same as those in Example 3; The preparation method of the reinforcing material includes the following steps: According to the mass ratio of halloysite nanotubes, deionized water, and metal oxide being 1.2:60:0.15, add the halloysite nanotubes into deionized water and treat them in an ultrasonic bath for 2.5 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then add the metal oxide and continue to treat in the ultrasonic bath for 2.5 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz). After that, stir at 35 °C for 1.5 h, and finally vacuum dry at 100 °C for 24 h to obtain the reinforcing material. Among them, the metal oxide is composed of molybdenum oxide nanometer, cerium oxide nanometer, and manganese dioxide nanometer mixed according to the mass ratio of 0.8:0.4:0.2.

[0042] Comparative Example 3 The difference between this comparative example and Example 3 is that when preparing the modified adhesive, in step S1, the metal oxide is composed of molybdenum oxide nanometer and cerium oxide nanometer mixed, and the remaining steps and raw materials are the same as those in Example 3; The preparation method of the reinforcing material includes the following steps: According to the mass ratio of nano-reinforcing filler, deionized water, and metal oxide being 1.2:60:0.15, add the nano-reinforcing filler into deionized water and treat them in an ultrasonic bath for 2.5 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then add the metal oxide and continue to treat in the ultrasonic bath for 2.5 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz). After that, stir at 35 °C for 1.5 h, and finally vacuum dry at 100 °C for 24 h to obtain the reinforcing material. Among them, the nano-reinforcing filler is composed of graphene oxide and halloysite nanotubes mixed according to the mass ratio of 0.9:0.6; the metal oxide is composed of molybdenum oxide nanometer and cerium oxide nanometer mixed according to the mass ratio of 0.8:0.6.

[0043] Comparative Example 4 The difference between this comparative example and Example 3 is that when preparing the modified adhesive, in step S1, the metal oxide is composed of molybdenum oxide nanometer and manganese dioxide nanometer mixed, and the remaining steps and raw materials are the same as those in Example 3; The preparation method of the reinforcing material includes the following steps: According to the mass ratio of nano-enhanced filler, deionized water, and metal oxide being 1.2:60:0.15, add the nano-enhanced filler into deionized water and treat it in an ultrasonic bath for 2.5 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then add the metal oxide and continue to treat it in the ultrasonic bath for 2.5 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz). After that, stir at 35 °C for 1.5 h, and finally vacuum dry at 100 °C for 24 h to obtain the enhanced material. Among them, the nano-enhanced filler is composed of graphene oxide and halloysite nanotubes mixed according to a mass ratio of 0.9:0.6; the metal oxide is composed of nano-molybdenum oxide and nano-manganese dioxide mixed according to a mass ratio of 0.8:0.6.

[0044] Comparative Example 5 The difference between this comparative example and Example 3 is that when preparing the modified adhesive, in step S1, the metal oxide is composed of nano-ceria and nano-manganese dioxide mixed, and the remaining steps and raw materials are the same as those in Example 3; The preparation method of the enhanced material includes the following steps: According to the mass ratio of nano-enhanced filler, deionized water, and metal oxide being 1.2:60:0.15, add the nano-enhanced filler into deionized water and treat it in an ultrasonic bath for 2.5 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then add the metal oxide and continue to treat it in the ultrasonic bath for 2.5 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz). After that, stir at 35 °C for 1.5 h, and finally vacuum dry at 100 °C for 24 h to obtain the enhanced material. Among them, the nano-enhanced filler is composed of graphene oxide and halloysite nanotubes mixed according to a mass ratio of 0.9:0.6; the metal oxide is composed of nano-ceria and nano-manganese dioxide mixed according to a mass ratio of 0.8:0.6.

[0045] Comparative Example 6 The difference between this comparative example and Example 3 is that when preparing the modified adhesive, in step S1, the enhanced material is composed of nano-enhanced filler and metal oxide mixed, and the remaining steps and raw materials are the same as those in Example 3; S1: According to the mass ratio of reinforcing material, 3-glycidoxypropyltriethoxysilane, ethanol and water mixture solution being 5.2:1.2:90, add the reinforcing material and 3-glycidoxypropyltriethoxysilane into the ethanol and water mixture solution (the volume ratio of ethanol to water is 9:1), then perform ultrasonic treatment for 35 min (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then stir at 65 °C for 22 h, filter, wash with ethanol 3 times (the mass of ethanol each time is 20% of the mass of the ethanol and water mixture solution), and finally perform vacuum drying at 65 °C for 48 h to obtain the silane reinforcing material. Among them, the reinforcing material is composed of a nano-reinforcing filler and a metal oxide mixed in a mass ratio of 1:1; the nano-reinforcing filler is composed of graphene oxide and halloysite nanotubes mixed in a mass ratio of 0.9:0.6; the metal oxide is composed of nano-molybdenum oxide, nano-cerium oxide and nano-manganese dioxide mixed in a mass ratio of 0.8:0.4:0.2.

[0046] Comparative Example 7 The difference between this comparative example and Example 3 is that when preparing the modified adhesive, the composite binder in step S2 is replaced with polyvinyl alcohol in equal mass, and the remaining steps and raw materials are the same as those in Example 3; S2: According to the mass ratio of polyvinyl alcohol, deionized water and silane reinforcing material being 10.2:120:0.6, add polyvinyl alcohol into deionized water, and stir at 95 °C for 1.5 h, then add the silane reinforcing material in step S1, and stir at 95 °C for 0.5 h to obtain a gel-like solution. Keep stirring the gel-like solution at 95 °C for 5.5 h. After completion, cool to room temperature, filter, and finally dry at room temperature for 24 h to obtain the modified adhesive.

[0047] Comparative Example 8 The difference between this comparative example and Example 3 is that when preparing the modified adhesive, the composite binder in step S2 is replaced with lignin aminated polyol in equal mass, and the remaining steps and raw materials are the same as those in Example 3; S2: According to the mass ratio of lignin aminated polyol, deionized water and silane reinforcing material being 10.2:120:0.6, add lignin aminated polyol into deionized water, and stir at 95 °C for 1.5 h, then add the silane reinforcing material in step S1, and stir at 95 °C for 0.5 h to obtain a gel-like solution. Keep stirring the gel-like solution at 95 °C for 5.5 h. After completion, cool to room temperature, filter, and finally dry at room temperature for 24 h to obtain the modified adhesive.

[0048] Comparative Example 9 The difference between this comparative example and Example 3 is that when preparing the maleic anhydride catalyst, the vanadium pentoxide nanowires are replaced with vanadium pentoxide in equal mass, and the remaining steps and raw materials are the same as those in Example 3; A phthalic anhydride catalyst, comprising an inert carrier and an upper catalyst A and a lower catalyst B respectively coated on the surface of the inert carrier; The upper catalyst A comprises the following raw materials in parts by weight: 1 part of vanadium pentoxide, 3 parts of composite nano-titanium dioxide, 3.5 parts of modified binder, 0.08 part of lanthanum oxide and 15 parts of deionized water; The lower catalyst B comprises the following raw materials in parts by weight: 1 part of vanadium pentoxide, 3 parts of composite nano-titanium dioxide, 3.5 parts of modified binder, 0.1 part of lanthanum oxide and 15 parts of deionized water; Among them, the composite nano-titanium dioxide is composed of anatase nano-titanium dioxide and rutile nano-titanium dioxide mixed in a mass ratio of 5:1; The inert carrier is a hollow cylindrical porcelain ring, and its specifications are outer diameter × height × thickness: 7.5 mm × 6 mm × 2 mm; A1: Preparation of the upper catalyst A: Weigh the raw materials in parts by weight. Mix vanadium pentoxide, composite nano-titanium dioxide, lanthanum oxide and deionized water, and then carry out ball milling. The ball milling time is 7 h, the ball milling speed is 300 rpm, use zirconia balls as the grinding balls, and the mass of the grinding balls is 8 times the mass of the composite nano-titanium dioxide (i.e., the ball-to-material ratio is 8:1). After the ball milling is completed, add the modified binder and stir at a speed of 500 rpm for 5 min to obtain the upper active component A. Weigh the inert carrier and put it into a rotating drum (the mass of the inert carrier accounts for 37.5% of the production capacity of the rotating drum), and then heat to 85 °C. Spray the upper active component A evenly on the surface of the inert carrier. The rotating drum rotates and heats (the rotation rate of the rotating drum is 30 rpm) until the coating is completely dried to obtain the upper catalyst A; A2: Preparation of the lower catalyst B: Weigh the raw materials in parts by weight. Mix vanadium pentoxide, composite nano-titanium dioxide, lanthanum oxide and deionized water, and then carry out ball milling. The ball milling time is 7 h, the ball milling speed is 300 rpm, use zirconia balls as the grinding balls, and the mass of the grinding balls is 8 times the mass of the composite nano-titanium dioxide (i.e., the ball-to-material ratio is 8:1). After the ball milling is completed, add the modified binder and stir at a speed of 500 rpm for 5 min to obtain the lower active component B. Weigh the inert carrier and put it into a rotating drum (the mass of the inert carrier accounts for 37.5% of the production capacity of the rotating drum), and then heat to 85 °C. Spray the lower active component B evenly on the surface of the inert carrier. The rotating drum rotates and heats (the rotation rate of the rotating drum is 30 rpm) until the coating is completely dried to obtain the lower catalyst B; A3: Packaging: Package the upper catalyst A in step A1 and the lower catalyst B in step A2, and finally obtain the phthalic anhydride catalyst.

[0049] The phthalic anhydride yields of the phthalic anhydride catalysts prepared in Examples 1-3 and Comparative Examples 1-9 were measured; the reaction experiment of oxidizing mesitylene to phthalic anhydride was carried out using the above catalysts. The specific operation steps for performance evaluation are as follows: (1) Loading: According to the mass ratio of the lower-layer catalyst B to the upper-layer catalyst A of 5:4, first load the lower-layer catalyst B in step A2 into a single-tube test device (the inner diameter of the reactor tube is 25 mm and the height is 4000 mm), and then load the upper-layer catalyst A in step A1. There is no other inert carrier in the middle. Control the total loading height to account for 70% of the single-tube height, the lower-layer catalyst B accounts for 50% of the total loading height, and the upper-layer catalyst A accounts for 50% of the total loading height to obtain the loaded phthalic anhydride catalyst; (2) Activation: Activate the phthalic anhydride catalyst loaded in step (1), introduce air at 1000 NL / h, control the heating rate at 7 °C / h, then heat up to 400 °C, and maintain this temperature for 30 h, and then cool down to 380 °C to complete the activation and obtain the activated phthalic anhydride catalyst; (3) Reaction: Vaporize mesitylene through a vaporizer and mix it with air, then introduce it into the single-tube test device equipped with the activated phthalic anhydride catalyst in step (2), and then start the reaction. After the reaction ends, measure the phthalic anhydride yield. Among them, the reaction conditions are: the air volume is 5 Nm 3 / h, the reaction temperature is 370 °C, and the mesitylene load is 70 g / h.

[0050] The measurement results are shown in Table 1 below: Table 1 Measurement Results of Phthalic Anhydride Catalysts Prepared in Examples 1-3 and Comparative Examples 1-9

[0051] As can be seen from the data in Table 1 above, by comparing Comparative Examples 1-6 with Example 3, it can be known that when the nano-enhanced filler in Step S1 is replaced with graphene oxide or halloysite nanotubes in equal mass, or the metal oxide is composed of a mixture of molybdenum oxide nanoparticles and cerium oxide nanoparticles, or the metal oxide is composed of a mixture of molybdenum oxide nanoparticles and manganese dioxide nanoparticles, or the metal oxide is composed of a mixture of cerium oxide nanoparticles and manganese dioxide nanoparticles, or the reinforcing material is composed of a mixture of nano-enhanced filler and metal oxide, and finally the phthalic anhydride catalyst is prepared, the test results are worse than those of Example 3. This shows that the nano-enhanced filler composed of a mixture of graphene oxide and halloysite nanotubes has a synergistic effect, which can effectively improve the catalytic efficiency and selectivity of the phthalic anhydride catalyst, increase the contact efficiency between the reactants and the active sites, and increase the phthalic anhydride yield; the metal oxide composed of a mixture of molybdenum oxide nanoparticles, cerium oxide nanoparticles and manganese dioxide nanoparticles has a synergistic effect, which can effectively improve the catalytic performance of the catalyst, further enhance the catalytic activity of the catalyst, and increase the phthalic anhydride yield; loading the metal oxide on the surface of the nano-enhanced filler can improve the dispersibility of the metal oxide, prevent its agglomeration, and improve the structural stability of the catalyst under high-temperature conditions, further improving the catalytic efficiency and increasing the phthalic anhydride yield. By comparing Comparative Examples 7-9 with Example 3, it can be known that when the composite binder in Step S2 is replaced with polyvinyl alcohol or lignin amino-functionalized polyol in equal mass, or the vanadium pentoxide nanowires are replaced with vanadium pentoxide in equal mass, and finally the phthalic anhydride catalyst is prepared, the test results are worse than those of Example 3. This shows that the composite binder composed of a mixture of polyvinyl alcohol and lignin amino-functionalized polyol has a synergistic effect, which can better improve the adhesion of the coating on the carrier, enhance the interfacial binding force between the active component and the carrier, and enhance the mechanical strength and thermal stability of the catalyst, further increasing the phthalic anhydride yield; using vanadium pentoxide nanowires to prepare the phthalic anhydride catalyst, the vanadium pentoxide nanowires have a high specific surface area, which can expose more active sites, effectively improve the catalytic activity of the catalyst, and further increase the phthalic anhydride yield.

[0052] As can be seen from Table 1 above, compared with the phthalic anhydride catalysts prepared in Comparative Examples 1-9, the phthalic anhydride catalysts prepared in Examples 1-3 are obtained by loading metal oxides with nano-enhancing fillers to prepare reinforcing materials, then combining the reinforcing materials with silane coupling agents, and then combining them with composite binders to obtain modified binders; vanadium pentoxide nanowires, composite nano-titanium dioxide, modified binders, additives and deionized water are mixed, and after ball milling, they are respectively coated on the surface of inert carriers, and finally phthalic anhydride catalysts are obtained, meeting the requirements of test performance. However, the phthalic anhydride catalysts prepared in Comparative Examples 1-9 do not meet the performance requirements standards, indicating that the phthalic anhydride catalysts prepared by the present invention not only have good catalytic performance, thermal stability and mechanical strength, but also enhance the adhesion of the coating on the carrier, improve the phthalic anhydride yield, and extend the service life of the catalyst, and its comprehensive performance is good.

[0053] In the description of the specification, the description with reference to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0054] The above content is only an example and illustration of the present invention. Those skilled in the art of the present technology can make various modifications or supplements to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined by the present invention, they should all belong to the protection scope of the present invention.

Claims

1. A phthalic anhydride catalyst, characterized in that, It includes an inert carrier, and an upper catalyst A and a lower catalyst B respectively coated on the surface of the inert carrier; The upper catalyst A includes the following raw materials in parts by weight: 0.5 - 1 part of vanadium pentoxide nanowires, 2 - 3 parts of composite nano-titanium dioxide, 2.5 - 3.5 parts of modified binder, 0.04 - 0.08 part of auxiliary agent, and 10 - 15 parts of deionized water; The lower catalyst B includes the following raw materials in parts by weight: 0.5 - 1 part of vanadium pentoxide nanowires, 2 - 3 parts of composite nano-titanium dioxide, 2.5 - 3.5 parts of modified binder, 0.06 - 0.1 part of auxiliary agent, and 10 - 15 parts of deionized water; The preparation method of the modified binder includes the following steps: S1: Combine the reinforcing material with the silane coupling agent to obtain a silane-reinforced material; S2: Combine the silane-reinforced material in step S1 with the composite binder to obtain a modified binder; The reinforcing material is prepared by loading metal oxides on nano-reinforcing fillers; The nano-reinforcing filler is composed of graphene oxide and halloysite nanotubes mixed in a mass ratio of 0.8 - 0.9:0.5 - 0.6; The metal oxide is composed of nano-molybdenum oxide, nano-cerium oxide and nano-manganese dioxide mixed in a mass ratio of 0.7 - 0.8:0.3 - 0.4:0.1 - 0.2; The composite binder is composed of polyvinyl alcohol and lignin aminated polyol mixed in a mass ratio of 0.6 - 0.7:0.4 - 0.

5.

2. The phthalic anhydride catalyst according to claim 1, wherein Step S1 is specifically as follows: Add the reinforcing material and the silane coupling agent into an ethanol and water mixed solution, then perform ultrasonic treatment for 25 - 35 min, then stir at 55 - 65 °C for 22 - 24 h, filter, wash with ethanol, and finally perform vacuum drying at 55 - 65 °C to obtain a silane-reinforced material.

3. The phthalic anhydride catalyst according to claim 2, characterized in that, The preparation method of the reinforcing material includes the following steps: Add the nano-reinforcing filler into deionized water, and treat it in an ultrasonic bath for 1.5 - 2.5 h, then add the metal oxide, and continue to treat it in the ultrasonic bath for 1.5 - 2.5 h. After completion, stir at 25 - 35 °C for 1.5 - 2.5 h, and finally perform vacuum drying at 90 - 100 °C to obtain a reinforcing material.

4. A phthalic anhydride catalyst according to claim 1, characterized in that Step S2 is specifically as follows: Add the composite binder into deionized water, and stir at 85 - 95 °C for 1.5 - 2.5 h, then add the silane-reinforced material in step S1, and stir at 85 - 95 °C for 0.5 - 1.5 h to obtain a gel-like solution. Continue to stir the gel-like solution at 85 - 95 °C for 5.5 - 6.5 h. After completion, cool to room temperature, filter, and finally dry at room temperature to obtain a modified binder.

5. The phthalic anhydride catalyst according to claim 1, characterized in that, The preparation method of the lignin aminated polyol includes the following steps: Mix alkali lignin, deionized water, diethanolamine and diisopropanolamine evenly, then heat to 75 - 85 °C, then add a formaldehyde solution, adjust the pH value of the system to 11.5 - 12.5 with a sodium hydroxide solution, then stir and react for 1.5 - 2.5 h. After the reaction is completed, precipitate with a sulfuric acid solution, filter, wash with deionized water, and finally perform vacuum drying at 45 - 55 °C to obtain a lignin aminated polyol.

6. The phthalic anhydride catalyst according to claim 1, characterized in that, The composite nano-titanium dioxide is composed of anatase nano-titanium dioxide and rutile nano-titanium dioxide mixed in a mass ratio of 4-5:

1.

7. A method for preparing the phthalic anhydride catalyst according to any one of claims 1-6, characterized in that, It includes the following steps: A1: Prepare the upper catalyst A: Weigh the raw materials in parts by mass. Mix vanadium pentoxide nanowires, composite nano-titanium dioxide, additives and deionized water, and then carry out ball milling. After the ball milling is completed, add a modified binder and stir for 5-10 minutes to obtain the upper active component A. Weigh an inert carrier and place it in a rotary drum, then heat it to 75-85 °C, and evenly spray the upper active component A on the surface of the inert carrier. The rotary drum rotates and heats at the same time until the coating is completely dried to obtain the upper catalyst A; A2: Prepare the lower catalyst B: Weigh the raw materials in parts by mass. Mix vanadium pentoxide nanowires, composite nano-titanium dioxide, additives and deionized water, and then carry out ball milling. After the ball milling is completed, add a modified binder and stir for 5-10 minutes to obtain the lower active component B. Weigh an inert carrier and place it in a rotary drum, then heat it to 75-85 °C, and evenly spray the lower active component B on the surface of the inert carrier. The rotary drum rotates and heats at the same time until the coating is completely dried to obtain the lower catalyst B; A3: Packaging: Package the upper catalyst A in step A1 and the lower catalyst B in step A2, and finally obtain the phthalic anhydride catalyst.

Images