A kind of homogeneous anhydride catalyst and preparation method thereof

Abstract

The invention relates to a homogenized anhydride catalyst and a preparation method thereof, belonging to the technical field of catalyst production. The 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: 0.5-1 parts of vanadium pentoxide nanowires, 2-3 parts of composite nano-titanium dioxide, 2.5-3.5 parts of a modified adhesive, 0.04-0.08 parts of an auxiliary agent and 10-15 parts of deionized water; the lower catalyst B comprises the following raw materials in parts by weight: 0.5-1 parts of vanadium pentoxide nanowires, 2-3 parts of composite nano-titanium dioxide, 2.5-3.5 parts of a modified adhesive, 0.06-0.1 parts of an auxiliary agent and 10-15 parts of deionized water; in the technical solution of the invention, a reinforcing material is combined with a silane coupling agent to obtain a silane reinforcing material; and the silane reinforcing material is combined with a composite binder to obtain a modified adhesive; thereby, the catalytic activity of the catalyst is well improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst production, and in particular relates to a homogeneous anhydride catalyst and a preparation method thereof. Background Art

[0002] Pyromellitic dianhydride (abbreviated as pyromellitic anhydride) is an important chemical raw material, primarily used in the synthesis of polyimides, epoxy resin curing matting agents, and polyester resin crosslinkers. Products made from pyromellitic anhydride are widely used in cutting-edge technologies such as aerospace, electronics, and high-performance composite materials. During the synthesis of pyromellitic anhydride, the performance of the catalyst largely determines the yield, selectivity, and purity of the product. Currently, common preparation processes for pyromellitic anhydride catalysts include spraying, impregnation, and sol-gel methods. The spraying method is widely adopted due to its ease of operation, uniform coating, and suitability for continuous production. This preparation method typically involves mixing the components in predetermined proportions to form a suspension, which is then sprayed onto the support surface using a spray gun to form an active coating of a certain thickness. Finally, the catalyst is activated by calcination, resulting in a pyromellitic anhydride catalyst with excellent catalytic performance. Although the spraying method for preparing pyromellitic anhydride catalysts is relatively mature, it still has some shortcomings in practical applications. Therefore, further improvements are needed in the overall performance of pyromellitic anhydride catalysts.

[0003] In the prior art, a spray coating method is used to prepare a homogeneous anhydride catalyst. However, due to the uneven distribution of its active components (such as vanadium pentoxide and metal oxides) on the carrier surface, the activity of some areas may be too high or too low, affecting the catalytic efficiency and selectivity of the catalyst. The contact efficiency between the reactants and the active sites is reduced, resulting in a decrease in the homogeneous anhydride yield. In addition, the coating is prone to shedding during the preparation process. High-strength binders (such as polyvinyl acetate) are usually used to enhance the adhesion of the coating to the carrier. However, these binders lose their adhesive effect due to decomposition during calcination and activation, resulting in weak interfacial bonding between the active components and the carrier. This makes it easy to peel off at high temperatures, and can cause the mechanical strength of the catalyst to decrease, affecting the service life of the catalyst. Summary of the Invention

[0004] The present invention aims to provide a homogeneous anhydride catalyst and a preparation method thereof. The invention comprises the following steps: preparing a reinforcing material by loading a metal oxide on a nano-reinforced filler; combining the reinforcing material with a silane coupling agent to obtain a silane-reinforced material; combining the silane-reinforced material in step S1 with a composite binder to obtain a modified binder; mixing vanadium pentoxide nanowires, composite nano-titanium dioxide, a modified binder, an additive and deionized water, ball-milling the mixture, and coating the mixture on an inert carrier to obtain an upper catalyst A and a lower catalyst B, which are then packaged separately to obtain a homogeneous anhydride catalyst. 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 between the active component and the carrier, increase the homogeneous anhydride yield, extend the service life of the catalyst, and generally improve the comprehensive performance of the homogeneous anhydride catalyst.

[0005] The technical problem to be solved by the present invention is as follows: In the prior art, a spraying method is used to prepare a homogeneous anhydride catalyst. However, due to the uneven distribution of its active components (such as vanadium pentoxide, metal oxides, etc.) on the carrier surface, the activity of some areas may be too high or too low, affecting the catalytic efficiency and selectivity of the catalyst, and the contact efficiency between the reactants and the active sites is reduced, resulting in a reduced homogeneous anhydride yield. In addition, the coating is prone to shedding during the preparation process. High-strength binders (such as polyvinyl acetate) are usually used to enhance the adhesion of the coating to the carrier. However, these binders lose their bonding effect due to decomposition during calcination and activation, resulting in weak interfacial bonding between the active components and the carrier, easy peeling at high temperatures, and a decrease in the mechanical strength of the catalyst, affecting the service life of the catalyst.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A homogeneous 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;

[0008] The upper catalyst A comprises the following raw materials in parts by weight: 0.5-1 parts of vanadium pentoxide nanowires, 2-3 parts of composite nano-titanium dioxide, 2.5-3.5 parts of modified binder, 0.04-0.08 parts of auxiliary agent and 10-15 parts of deionized water;

[0009] The lower layer catalyst B comprises the following raw materials in parts by weight: 0.5-1 parts of vanadium pentoxide nanowires, 2-3 parts of composite nano-titanium dioxide, 2.5-3.5 parts of modified binder, 0.06-0.1 parts of auxiliary agent and 10-15 parts of deionized water;

[0010] The preparation method of the modified adhesive comprises the following steps:

[0011] S1: Silane-reinforced material is obtained by combining the reinforcing material with the silane coupling agent;

[0012] S2: combining the silane reinforcement material in step S1 with a composite adhesive to obtain a modified adhesive;

[0013] The reinforcing material is prepared by loading metal oxides with nano-reinforced fillers.

[0014] Furthermore, step S1 is specifically as follows:

[0015] The reinforcing material and the silane coupling agent are added to a mixed solution of ethanol and water, and then ultrasonically treated for 25-35 minutes, stirred at 55-65° C. for 22-24 hours, filtered, washed with ethanol, and finally vacuum dried at 55-65° C. to obtain a silane reinforced material.

[0016] During the above reaction process, the surface of the reinforcing material has hydroxyl groups. The silane coupling agent can produce silanol groups after hydrolysis. The silanol groups on the silane coupling agent can combine with the hydroxyl groups on the reinforcing material, and the silane coupling agent is grafted to the surface of the reinforcing material to finally obtain a silane reinforced material.

[0017] Furthermore, the mass ratio of the reinforcing material, the silane coupling agent, the ethanol and the water mixed solution is 4.8-5.2:0.8-1.2:80-90.

[0018] Furthermore, the silane coupling agent is 3-glycidyloxypropyltriethoxysilane.

[0019] Furthermore, the preparation method of the reinforcing material comprises the following steps:

[0020] The nano-reinforced filler is added to deionized water and treated in an ultrasonic bath for 1.5-2.5 hours, and then the metal oxide is added and treated in an ultrasonic bath for 1.5-2.5 hours. After the treatment, the mixture is stirred at 25-35° C. for 1.5-2.5 hours and finally vacuum dried at 90-100° C. to obtain a reinforced material.

[0021] During the above reaction process, the metal oxide can be loaded on the surface of the nano-reinforced filler through hydrogen bond interaction, thereby combining the nano-reinforced filler and the metal oxide together to finally obtain a reinforced material.

[0022] Furthermore, the mass ratio of the nano-reinforced filler, deionized water, and metal oxide is 0.8-1.2:50-60:0.05-0.15.

[0023] Furthermore, the nano-reinforced filler is composed of a mixture of graphene oxide and halloysite nanotubes in a mass ratio of 0.8-0.9:0.5-0.6.

[0024] Furthermore, 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.

[0025] Furthermore, step S2 is specifically as follows:

[0026] The composite adhesive is added to deionized water and stirred at 85-95° C. for 1.5-2.5 hours. The silane reinforcing material in step S1 is then added and stirred at 85-95° C. for 0.5-1.5 hours to obtain a gel solution. The gel solution is further stirred at 85-95° C. for 5.5-6.5 hours. After the stirring, the solution is cooled to room temperature, filtered, and finally dried at room temperature to obtain a modified adhesive.

[0027] During the above reaction process, the composite adhesive has a hydroxyl group, and the silane coupling agent in the silane reinforcement material has an epoxy group. The hydroxyl group on the composite adhesive can combine with the epoxy group on the silane reinforcement material through a ring-opening reaction, thereby combining the composite adhesive and the silane reinforcement material together to finally obtain a modified adhesive.

[0028] Furthermore, the mass ratio of the composite adhesive, deionized water, and silane reinforcing material is 9.8-10.2:100-120:0.4-0.6.

[0029] Furthermore, the composite adhesive is composed of polyvinyl alcohol and lignin amino polyol mixed in a mass ratio of 0.6-0.7:0.4-0.5.

[0030] Furthermore, the preparation method of the lignin amino polyol comprises the following steps:

[0031] Alkali lignin, deionized water, diethanolamine and diisopropanolamine are mixed evenly, then heated to 75-85°C, and then formaldehyde solution is added. The pH value of the system is adjusted to 11.5-12.5 with sodium hydroxide solution, and then stirred for reaction for 1.5-2.5 hours. After the reaction is completed, sulfuric acid solution is used for precipitation, filtered, washed with deionized water, and finally vacuum dried at 45-55°C to obtain lignin amino polyol.

[0032] During the above reaction process, the alkali lignin has a phenolic hydroxyl group, and the adjacent carbon atom of the phenolic hydroxyl group has an active hydrogen atom. Both diethanolamine and diisopropanolamine have amino groups. The amino groups in diethanolamine and diisopropanolamine can undergo a Mannich reaction with the active hydrogen atoms in the alkali lignin in the presence of formaldehyde, thereby combining the alkali lignin with the diethanolamine and diisopropanolamine to finally obtain a lignin amino polyol.

[0033] Furthermore, 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.

[0034] A method for preparing a homogeneous anhydride catalyst comprises the following steps:

[0035] A1: Preparation of upper catalyst A:

[0036] Weigh parts by mass of raw materials, mix vanadium pentoxide nanowires, composite nano-titanium dioxide, additives, and deionized water, and then ball-mill. After the ball-milling is completed, add a modified binder and stir for 5-10 minutes to obtain an upper layer of 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 layer of active component A onto the surface of the inert carrier. The drum is rotated and heated until the coating is completely dried to obtain an upper layer of catalyst A.

[0037] A2: Preparation of lower layer catalyst B:

[0038] Weigh parts by mass of raw materials, mix vanadium pentoxide nanowires, composite nano-titanium dioxide, additives, and deionized water, and then ball-mill. After the ball milling is completed, add a modified binder and stir at a speed of 300-500 rpm for 5-10 minutes to obtain a lower layer of 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 layer of active component B on the surface of the inert carrier. The drum is rotated and heated until the coating is completely dried to obtain a lower layer of catalyst B.

[0039] A3: Repackaging:

[0040] The upper layer catalyst A in step A1 and the lower layer catalyst B in step A2 are packaged separately to finally obtain a homogeneous anhydride catalyst.

[0041] 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.

[0042] Furthermore, the auxiliary agent is lanthanum oxide.

[0043] Furthermore, the ball milling time is 6-7 hours, and the ball milling speed is 300-400 rpm.

[0044] Furthermore, the inert carrier is a hollow cylindrical ceramic ring with the following specifications: outer diameter × height × thickness: 7.5 mm × 6 mm × 2 mm.

[0045] Furthermore, the method for preparing the vanadium pentoxide nanowires comprises the following steps:

[0046] Vanadium pentoxide was added to deionized water, followed by hydrogen peroxide solution, and stirred for 2 hours. Disodium citrate was then added, stirred evenly, and transferred to a Teflon-lined stainless steel autoclave and kept at 180°C for 24 hours. The mixture was cooled to room temperature, washed with ethanol three times, and then dried at 60°C for 24 hours. The mixture was then placed in a muffle furnace and sintered in air at 300°C for 2 hours to obtain vanadium pentoxide nanowires.

[0047] Furthermore, the mass ratio of the vanadium pentoxide, deionized water, hydrogen peroxide solution, and disodium citrate is 0.36:30:15:0.23.

[0048] The invention discloses an application of a homoanhydride catalyst in the oxidation of durene to produce homoanhydride.

[0049] Beneficial effects of the present invention:

[0050] (1) In the technical solution of the present invention, a reinforced material is prepared by loading metal oxides on nano-reinforced fillers; the nano-reinforced fillers are 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, which provides a larger specific surface area and is conducive to the uniform dispersion of active components. Halloysite nanotubes have a one-dimensional hollow tubular structure, which provides more acid sites and is conducive 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 to highly disperse the active components, provides more contact sites for reactants, and enhances the mechanical strength and thermal stability of the homogenized anhydride catalyst, but also can better load the metal oxide and increase its dispersibility, and improve the nanostructured anhydride catalyst. The invention relates to a novel nanostructured carbon fiber composite material, wherein the nanostructured carbon fiber composite material is a nanostructured carbon fiber composite material, and the nanostructured carbon fiber composite material is a nanostructured carbon fiber composite material. The ...

[0051] (2) In the technical solution of the present invention, a modified adhesive is obtained by combining a silane reinforcing material with a composite adhesive; the composite adhesive is composed of a mixture of polyvinyl alcohol and lignin amino polyol; the two have a synergistic effect and have good bonding properties, 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. Polyvinyl alcohol is a water-soluble polymer with good environmental protection. Lignin amino polyol also has good thermal stability and helps to improve the catalytic efficiency of the catalyst. Polyvinyl alcohol and lignin amino polyol are mixed, and the mixture has good adhesion with the silane reinforcing material. The invention has good binding force, can further improve the mechanical strength and thermal stability of the catalyst, can better improve the catalytic activity and selectivity of the catalyst, increase the yield of the anhydride, and extend the service life of the catalyst; vanadium pentoxide nanowires, composite nano-titanium dioxide, modified adhesive, additives and deionized water are mixed, ball-milled, and then coated on an inert carrier respectively to obtain an upper layer catalyst A and a lower layer catalyst B, which are packaged separately to finally obtain the anhydride catalyst; the modified adhesive effectively improves the overall comprehensive performance of the anhydride catalyst, increases the yield of the anhydride, and the catalytic performance and the yield of the anhydride of the catalyst are significantly improved compared with the products of the same period on the market.

[0052] (3) In the technical solution of the present invention, a reinforcing material is prepared by loading a metal oxide on a nano-reinforced filler, and then the reinforcing material is combined with a silane coupling agent and then combined with a composite binder to obtain a modified binder; vanadium pentoxide nanowires, composite nano-titanium dioxide, a modified binder, an additive and deionized water are mixed, ball-milled and coated on an inert carrier respectively to obtain a homogenous anhydride catalyst; the catalytic performance, thermal stability and mechanical strength of the homogenous anhydride catalyst are improved as a whole, and the adhesion of the coating on the inert carrier is enhanced, the homogenous anhydride yield is increased, the service life of the homogenous anhydride catalyst is extended, the environmental protection is good, and the overall comprehensive performance is good. DETAILED DESCRIPTION

[0053] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0054] The specific parameters of the raw materials used in the present invention are as follows:

[0055] 3-Glycidyloxypropyltriethoxysilane, CAS No.: 2602-34-8, Product No.: G832117, provided by Shanghai McLean Biochemical Technology Co., Ltd.; graphene oxide, No.: XF002-2, provided by Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.; halloysite nanotubes, provided by Angxing New Carbon Materials Changzhou Co., Ltd.; nano-molybdenum oxide, Product No.: JL-MoO3-N20, provided by Ningbo Jinlei Nanomaterials Technology Co., Ltd.; nano-cerium oxide, particle size: 30 nm, purity: 99.99%, provided by Ningbo Luofei Nanotechnology Co., Ltd.; nano-manganese dioxide, particle size / mesh: 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 McLean Biochemical Technology Co., Ltd.; anatase nano-titanium dioxide, model: VK-TA18, particle size: 20nm, provided by Xuancheng Jingrui New Materials Co., Ltd.; rutile nano-titanium dioxide, provided by Qinghe County Ruijiang Metal Materials Co., Ltd.

[0056] The preparation method of vanadium pentoxide nanowires comprises the following steps:

[0057] According to the mass ratio of vanadium pentoxide, deionized water, hydrogen peroxide solution and disodium citrate of 0.36:30:15:0.23, vanadium pentoxide was added to deionized water, and then 30wt% hydrogen peroxide solution was added and stirred for 2h. Then, disodium citrate was added, stirred evenly, and transferred to a 100mL Teflon-lined stainless steel high-pressure reactor and kept at 180°C for 24h. After cooling to room temperature, it was washed with ethanol three times (the mass of ethanol each time was 40% of the mass of deionized water), and then dried at 60°C for 24h. Then, it was placed in a muffle furnace and sintered in air at 300°C for 2h to finally obtain vanadium pentoxide nanowires.

[0058] Example 1

[0059] The modified adhesive is prepared by the following steps:

[0060] S1: According to the mass ratio of the reinforcing material, 3-glycidyloxypropyltriethoxysilane, and the mixed solution of ethanol and water being 4.8:0.8:80, the reinforcing material and 3-glycidyloxypropyltriethoxysilane were added to a mixed solution of ethanol and water (the volume ratio of ethanol and water was 9:1), and then ultrasonically treated for 25 minutes (ultrasonic power of 100W, ultrasonic frequency of 40kHz), and then stirred at 55°C for 24 hours. After filtering, the mixture was washed three times with ethanol (the mass of ethanol each time was 20% of the mass of the mixed solution of ethanol and water), and finally vacuum dried at 55°C for 48 hours to obtain a silane reinforced material;

[0061] The preparation method of the reinforcement material comprises the following steps:

[0062] According to the mass ratio of nano-reinforced filler, deionized water and metal oxide being 0.8:50:0.05, the nano-reinforced filler is added to deionized water and treated in an ultrasonic bath for 1.5 hours (ultrasonic power of 100 W, ultrasonic frequency of 40 kHz), and then the metal oxide is added and treated in an ultrasonic bath for 1.5 hours (ultrasonic power of 100 W, ultrasonic frequency of 40 kHz). After the end, the mixture is stirred at 25° C. for 2.5 hours and finally vacuum-dried at 90° C. for 24 hours to obtain a reinforced material, wherein the nano-reinforced filler is composed of a mixture of graphene oxide and halloysite nanotubes in a mass ratio of 0.8:0.5; the metal oxide is composed of a mixture of nano-molybdenum oxide, nano-cerium oxide and nano-manganese dioxide in a mass ratio of 0.7:0.3:0.1;

[0063] S2: adding the composite binder to deionized water in a mass ratio of 9.8:100:0.4 among the composite binder, deionized water, and silane reinforcing material, and stirring at 85°C for 2.5 hours, then adding the silane reinforcing material in step S1, and stirring at 85°C for 1.5 hours to obtain a gel solution, and continuing to stir the gel solution at 85°C for 6.5 hours. After the end, cooling to room temperature, filtering, and finally drying at room temperature for 24 hours to obtain a modified adhesive, wherein the composite binder is composed of polyvinyl alcohol and lignin amino polyol mixed in a mass ratio of 0.6:0.4;

[0064] The preparation method of lignin amination polyol comprises the following steps:

[0065] According to the mass ratio of alkali lignin, deionized water, diethanolamine and diisopropanolamine of 2.8:10:3.8:1.8, alkali lignin, deionized water, diethanolamine and diisopropanolamine were mixed uniformly, then heated to 75°C, and then 37wt% formaldehyde solution was added (the mass of the formaldehyde solution was 1.2 times the mass of the alkali lignin), and the pH value of the system was adjusted to 11.5 with 1mol / L sodium hydroxide solution, and then stirred for 1.5h. After the reaction, 10wt% sulfuric acid solution was used for precipitation (the mass of the sulfuric acid solution and the deionized water were equal), filtered, washed with deionized water three times (the mass of the deionized water each time was 1.5 times the mass of the above deionized water), and finally vacuum dried at 45°C for 24h to obtain lignin amino polyol;

[0066] A homogeneous 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;

[0067] The upper layer catalyst A comprises the following raw materials in parts by weight: 0.5 parts of vanadium pentoxide nanowires, 2 parts of composite nano-titanium dioxide, 2.5 parts of modified binder, 0.04 parts of lanthanum oxide and 10 parts of deionized water;

[0068] The lower layer catalyst B comprises the following raw materials in parts by weight: 0.5 parts of vanadium pentoxide nanowires, 2 parts of composite nano-titanium dioxide, 2.5 parts of modified binder, 0.06 parts of lanthanum oxide and 10 parts of deionized water;

[0069] 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.

[0070] The inert carrier is a hollow cylindrical ceramic ring with the following specifications: outer diameter × height × thickness: 7.5 mm × 6 mm × 2 mm;

[0071] A1: Preparation of upper catalyst A:

[0072] Weigh the raw materials by mass, mix the vanadium pentoxide nanowires, composite nano-titanium dioxide, lanthanum oxide and deionized water, and then ball mill for 6 hours at a ball milling speed of 400 rpm. Use zirconia balls as 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 a modified binder and stir at a speed of 300 rpm for 10 minutes to obtain an upper layer of active component A. Weigh an inert carrier and place it in a rotary drum (the mass of the inert carrier accounts for 37.5% of the production capacity of the rotary drum). Then heat it to 75°C, evenly spray the upper layer of active component A on the surface of the inert carrier, and heat the drum while rotating (the drum rotates at a speed of 30 rpm) until the coating is completely dried to obtain an upper layer of catalyst A.

[0073] A2: Preparation of lower layer catalyst B:

[0074] Weigh the raw materials by mass, mix the vanadium pentoxide nanowires, composite nano-titanium dioxide, lanthanum oxide and deionized water, and then ball mill for 6 hours at a ball milling speed of 400 rpm. Use zirconia balls as 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 a modified binder and stir at a speed of 300 rpm for 10 minutes to obtain a lower layer of active component B. Weigh an inert carrier and place it in a rotary drum (the mass of the inert carrier accounts for 37.5% of the production capacity of the rotary drum). Then heat it to 75°C, evenly spray the lower layer of active component B on the surface of the inert carrier, and heat the drum while rotating (the drum rotates at a speed of 30 rpm) until the coating is completely dried to obtain a lower layer of catalyst B.

[0075] A3: Repackaging:

[0076] The upper layer catalyst A in step A1 and the lower layer catalyst B in step A2 are packaged separately to finally obtain a homogeneous anhydride catalyst.

[0077] Example 2

[0078] The modified adhesive is prepared by the following steps:

[0079] S1: According to the mass ratio of reinforcing material, 3-glycidyloxypropyltriethoxysilane, ethanol and water mixed solution of 5:1:85, the reinforcing material and 3-glycidyloxypropyltriethoxysilane were added to the ethanol and water mixed solution (the volume ratio of ethanol and water was 9:1), and then ultrasonically treated for 30 minutes (ultrasonic power of 100W, ultrasonic frequency of 40kHz), and then stirred at 60°C for 23 hours. After filtering, it was washed with ethanol three times (the mass of ethanol each time was 20% of the mass of the ethanol and water mixed solution), and finally vacuum dried at 60°C for 48 hours to obtain a silane reinforced material;

[0080] The preparation method of the reinforcement material comprises the following steps:

[0081] According to the mass ratio of nano-reinforced filler, deionized water and metal oxide being 1:55:0.1, the nano-reinforced filler is added to deionized water and treated in an ultrasonic bath for 2 hours (ultrasonic power of 100 W, ultrasonic frequency of 40 kHz), and then the metal oxide is added and treated in an ultrasonic bath for another 2 hours (ultrasonic power of 100 W, ultrasonic frequency of 40 kHz). After completion, the mixture is stirred at 30° C. for 2 hours and finally vacuum-dried at 95° C. for 24 hours to obtain a reinforced material, wherein the nano-reinforced filler is composed of a mixture of graphene oxide and halloysite nanotubes in a mass ratio of 0.85:0.55; the metal oxide is composed of a mixture of nano-molybdenum oxide, nano-cerium oxide and nano-manganese dioxide in a mass ratio of 0.75:0.35:0.15;

[0082] S2: adding the composite binder to deionized water according to the mass ratio of the composite binder, deionized water, and silane reinforcing material to 10:110:0.5, and stirring at 90°C for 2 hours, then adding the silane reinforcing material in step S1, and stirring at 90°C for 1 hour to obtain a gel solution, and continuing to stir the gel solution at 90°C for 6 hours. After the end, cooling to room temperature, filtering, and finally drying at room temperature for 24 hours to obtain a modified adhesive, wherein the composite binder is composed of polyvinyl alcohol and lignin amino polyol mixed in a mass ratio of 0.65:0.45;

[0083] The preparation method of lignin amination polyol comprises the following steps:

[0084] Alkali lignin, deionized water, diethanolamine, and diisopropanolamine were mixed uniformly according to a mass ratio of 3:12:4:2, and then heated to 80°C. 37wt% formaldehyde solution was added (the mass of the formaldehyde solution was 1.2 times the mass of the alkali lignin), and the pH value of the system was adjusted to 12 with a 1mol / L sodium hydroxide solution. The mixture was stirred and reacted for 2 hours. After the reaction was completed, 10wt% sulfuric acid solution was used for precipitation (the mass of the sulfuric acid solution was equal to that of the deionized water), the mixture was filtered, and the mixture was washed three times with deionized water (the mass of the deionized water each time was 1.5 times the mass of the above deionized water). Finally, the mixture was vacuum dried at 50°C for 24 hours to obtain lignin amino polyol.

[0085] A homogeneous 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;

[0086] The upper catalyst A comprises the following raw materials in parts by weight: 0.8 parts of vanadium pentoxide nanowires, 2.5 parts of composite nano-titanium dioxide, 3 parts of modified binder, 0.06 parts of lanthanum oxide and 12 parts of deionized water;

[0087] The lower layer catalyst B comprises the following raw materials in parts by weight: 0.8 parts of vanadium pentoxide nanowires, 2.5 parts of composite nano-titanium dioxide, 3 parts of modified binder, 0.08 parts of lanthanum oxide and 12 parts of deionized water;

[0088] 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.

[0089] The inert carrier is a hollow cylindrical ceramic ring with the following specifications: outer diameter × height × thickness: 7.5 mm × 6 mm × 2 mm;

[0090] A1: Preparation of upper catalyst A:

[0091] Weigh parts by mass of raw materials, mix vanadium pentoxide nanowires, composite nano-titanium dioxide, lanthanum oxide and deionized water, and then ball mill for 6.5 hours at a ball milling speed of 350 rpm. Use zirconia balls as 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 a modified binder and stir at a speed of 400 rpm for 8 minutes to obtain an upper layer of active component A. Weigh an inert carrier and place it in a rotary drum (the mass of the inert carrier accounts for 37.5% of the production capacity of the rotary drum). Then heat it to 80°C, evenly spray the upper layer of active component A on the surface of the inert carrier, and heat the drum while rotating (the drum rotates at a speed of 30 rpm) until the coating is completely dried to obtain an upper layer of catalyst A.

[0092] A2: Preparation of lower layer catalyst B:

[0093] Weigh parts by mass of raw materials, mix vanadium pentoxide nanowires, composite nano-titanium dioxide, lanthanum oxide and deionized water, and then ball mill for 6.5 hours at a ball milling speed of 350 rpm. Use zirconia balls as 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 a modified binder and stir at a speed of 400 rpm for 8 minutes to obtain a lower layer of active component B. Weigh an inert carrier and place it in a rotary drum (the mass of the inert carrier accounts for 37.5% of the production capacity of the rotary drum). Then heat it to 80°C, evenly spray the lower layer of active component B on the surface of the inert carrier, and heat the drum while rotating (the drum rotates at a speed of 30 rpm) until the coating is completely dried to obtain a lower layer of catalyst B.

[0094] A3: Repackaging:

[0095] The upper layer catalyst A in step A1 and the lower layer catalyst B in step A2 are packaged separately to finally obtain a homogeneous anhydride catalyst.

[0096] Example 3

[0097] The modified adhesive is prepared by the following specific steps:

[0098] S1: According to the mass ratio of the reinforcing material, 3-glycidyloxypropyltriethoxysilane, and the mixed solution of ethanol and water being 5.2:1.2:90, the reinforcing material and 3-glycidyloxypropyltriethoxysilane were added to a mixed solution of ethanol and water (the volume ratio of ethanol and water was 9:1), and then ultrasonically treated for 35 minutes (ultrasonic power of 100W, ultrasonic frequency of 40kHz), and then stirred at 65°C for 22 hours. After filtering, the mixture was washed three times with ethanol (the mass of ethanol each time was 20% of the mass of the mixed solution of ethanol and water), and finally vacuum dried at 65°C for 48 hours to obtain a silane reinforced material;

[0099] The preparation method of the reinforcement material comprises the following steps:

[0100] According to the mass ratio of nano-reinforced filler, deionized water and metal oxide of 1.2:60:0.15, the nano-reinforced filler is added to deionized water and treated in an ultrasonic bath for 2.5 hours (ultrasonic power of 100 W, ultrasonic frequency of 40 kHz), and then the metal oxide is added and treated in an ultrasonic bath for 2.5 hours (ultrasonic power of 100 W, ultrasonic frequency of 40 kHz). After the end, the mixture is stirred at 35°C for 1.5 hours and finally vacuum dried at 100°C for 24 hours to obtain a reinforced material, wherein the nano-reinforced filler is composed of a mixture of graphene oxide and halloysite nanotubes in a mass ratio of 0.9:0.6; the metal oxide is composed of a mixture of nano-molybdenum oxide, nano-cerium oxide and nano-manganese dioxide in a mass ratio of 0.8:0.4:0.2;

[0101] S2: adding the composite binder to deionized water according to the mass ratio of the composite binder, deionized water, and silane reinforcing material to 10.2:120:0.6, and stirring at 95°C for 1.5 hours, then adding the silane reinforcing material in step S1, and stirring at 95°C for 0.5 hours to obtain a gel solution, and continuing to stir the gel solution at 95°C for 5.5 hours. After the end, cooling to room temperature, filtering, and finally drying at room temperature for 24 hours to obtain a modified adhesive, wherein the composite binder is composed of polyvinyl alcohol and lignin amino polyol mixed in a mass ratio of 0.7:0.5;

[0102] The preparation method of lignin amination polyol comprises the following steps:

[0103] According to the mass ratio of alkali lignin, deionized water, diethanolamine and diisopropanolamine of 3.2:15:4.2:2.2, the alkali lignin, deionized water, diethanolamine and diisopropanolamine were mixed uniformly, and then heated to 85°C, and then 37wt% formaldehyde solution was added (the mass of the formaldehyde solution was 1.2 times the mass of the alkali lignin), and the pH value of the system was adjusted to 12.5 with 1mol / L sodium hydroxide solution, and then stirred for 2.5h. After the reaction, 10wt% sulfuric acid solution was used for precipitation (the mass of the sulfuric acid solution was equal to that of the deionized water), filtered, washed with deionized water three times (the mass of the deionized water each time was 1.5 times the mass of the above deionized water), and finally vacuum dried at 55°C for 24h to obtain lignin amino polyol;

[0104] A homogeneous 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;

[0105] The upper catalyst A comprises 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 parts of lanthanum oxide and 15 parts of deionized water;

[0106] The lower layer catalyst B comprises 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;

[0107] 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.

[0108] The inert carrier is a hollow cylindrical ceramic ring with the following specifications: outer diameter × height × thickness: 7.5 mm × 6 mm × 2 mm;

[0109] A1: Preparation of upper catalyst A:

[0110] Weigh the raw materials by mass, mix the vanadium pentoxide nanowires, composite nano-titanium dioxide, lanthanum oxide and deionized water, and then ball mill for 7 hours at a ball milling speed of 300 rpm. Use zirconia balls as 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 a modified binder and stir at a speed of 500 rpm for 5 minutes to obtain an upper layer of active component A. Weigh an inert carrier and place it in a rotary drum (the mass of the inert carrier accounts for 37.5% of the production capacity of the rotary drum). Then heat it to 85°C, evenly spray the upper layer of active component A on the surface of the inert carrier, and heat the drum while rotating (the drum rotates at a speed of 30 rpm) until the coating is completely dried to obtain an upper layer of catalyst A.

[0111] A2: Preparation of lower layer catalyst B:

[0112] Weigh the raw materials by mass, mix the vanadium pentoxide nanowires, composite nano-titanium dioxide, lanthanum oxide and deionized water, and then ball mill for 7 hours at a ball milling speed of 300 rpm. Use zirconia balls as 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 a modified binder and stir at a speed of 500 rpm for 5 minutes to obtain a lower layer of active component B. Weigh an inert carrier and place it in a rotary drum (the mass of the inert carrier accounts for 37.5% of the production capacity of the rotary drum). Then heat it to 85°C, evenly spray the lower layer of active component B on the surface of the inert carrier, and heat the drum while rotating (the drum rotation rate is 30 rpm) until the coating is completely dried to obtain a lower layer catalyst B.

[0113] A3: Repackaging:

[0114] The upper layer catalyst A in step A1 and the lower layer catalyst B in step A2 are packaged separately to finally obtain a homogeneous anhydride catalyst.

[0115] Comparative Example 1

[0116] The difference between this comparative example and Example 3 is that, when preparing the modified adhesive, the mass of the nano-reinforced filler in step S1 is replaced by graphene oxide, and the remaining steps and raw materials are the same as those in Example 3;

[0117] The preparation method of the reinforcement material comprises the following steps:

[0118] According to the mass ratio of graphene oxide, deionized water and metal oxide of 1.2:60:0.15, graphene oxide was added to deionized water and treated in an ultrasonic bath for 2.5 hours (ultrasonic power of 100 W, ultrasonic frequency of 40 kHz), and then the metal oxide was added and continued to be treated in the ultrasonic bath for 2.5 hours (ultrasonic power of 100 W, ultrasonic frequency of 40 kHz). After the end, the mixture was stirred at 35°C for 1.5 hours and finally vacuum dried at 100°C for 24 hours to obtain a reinforced material, wherein the metal oxide was composed of nano-molybdenum oxide, nano-cerium oxide and nano-manganese dioxide mixed in a mass ratio of 0.8:0.4:0.2.

[0119] Comparative Example 2

[0120] The difference between this comparative example and Example 3 is that, when preparing the modified adhesive, the mass of the nano-reinforced filler in step S1 is replaced by halloysite nanotubes, and the remaining steps and raw materials are the same as those in Example 3;

[0121] The preparation method of the reinforcement material comprises the following steps:

[0122] According to the mass ratio of halloysite nanotubes, deionized water and metal oxide being 1.2:60:0.15, halloysite nanotubes are added to deionized water and treated in an ultrasonic bath for 2.5 hours (ultrasonic power of 100 W, ultrasonic frequency of 40 kHz), then the metal oxide is added and treated in the ultrasonic bath for another 2.5 hours (ultrasonic power of 100 W, ultrasonic frequency of 40 kHz). After the treatment, the mixture is stirred at 35°C for 1.5 hours and finally vacuum dried at 100°C for 24 hours to obtain a reinforced material, wherein 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.

[0123] Comparative Example 3

[0124] The difference between this comparative example and Example 3 is that, when preparing the modified adhesive, in step S1, the metal oxide is a mixture of nano-molybdenum oxide and nano-cerium oxide, and the remaining steps and raw materials are the same as those in Example 3;

[0125] The preparation method of the reinforcement material comprises the following steps:

[0126] According to the mass ratio of nano-reinforced filler, deionized water and metal oxide of 1.2:60:0.15, the nano-reinforced filler was added to deionized water and treated in an ultrasonic bath for 2.5 hours (ultrasonic power of 100 W, ultrasonic frequency of 40 kHz), and then the metal oxide was added and continued to be treated in the ultrasonic bath for 2.5 hours (ultrasonic power of 100 W, ultrasonic frequency of 40 kHz). After the end, the mixture was stirred at 35°C for 1.5 hours and finally vacuum dried at 100°C for 24 hours to obtain a reinforced material, wherein the nano-reinforced filler was composed of a mixture of graphene oxide and halloysite nanotubes in a mass ratio of 0.9:0.6; the metal oxide was composed of a mixture of nano-molybdenum oxide and nano-cerium oxide in a mass ratio of 0.8:0.6.

[0127] Comparative Example 4

[0128] The difference between this comparative example and Example 3 is that, when preparing the modified adhesive, in step S1, the metal oxide is a mixture of nano-molybdenum oxide and nano-manganese dioxide, and the remaining steps and raw materials are the same as those in Example 3;

[0129] The preparation method of the reinforcement material comprises the following steps:

[0130] According to the mass ratio of nano-reinforced filler, deionized water and metal oxide of 1.2:60:0.15, the nano-reinforced filler was added to deionized water and treated in an ultrasonic bath for 2.5 hours (ultrasonic power of 100 W, ultrasonic frequency of 40 kHz), and then the metal oxide was added and continued to be treated in the ultrasonic bath for 2.5 hours (ultrasonic power of 100 W, ultrasonic frequency of 40 kHz). After the end, the mixture was stirred at 35°C for 1.5 hours and finally vacuum dried at 100°C for 24 hours to obtain a reinforced material, wherein the nano-reinforced filler was composed of a mixture of graphene oxide and halloysite nanotubes in a mass ratio of 0.9:0.6; the metal oxide was composed of a mixture of nano-molybdenum oxide and nano-manganese dioxide in a mass ratio of 0.8:0.6.

[0131] Comparative Example 5

[0132] 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 a mixture of nano-cerium oxide and nano-manganese dioxide, and the remaining steps and raw materials are the same as those in Example 3;

[0133] The preparation method of the reinforcement material comprises the following steps:

[0134] According to the mass ratio of nano-reinforced filler, deionized water and metal oxide of 1.2:60:0.15, the nano-reinforced filler was added to deionized water and treated in an ultrasonic bath for 2.5 hours (ultrasonic power of 100 W, ultrasonic frequency of 40 kHz), and then the metal oxide was added and continued to be treated in the ultrasonic bath for 2.5 hours (ultrasonic power of 100 W, ultrasonic frequency of 40 kHz). After the end, the mixture was stirred at 35°C for 1.5 hours and finally vacuum dried at 100°C for 24 hours to obtain a reinforced material, wherein the nano-reinforced filler was composed of a mixture of graphene oxide and halloysite nanotubes in a mass ratio of 0.9:0.6; the metal oxide was composed of a mixture of nano-cerium oxide and nano-manganese dioxide in a mass ratio of 0.8:0.6.

[0135] Comparative Example 6

[0136] The difference between this comparative example and Example 3 is that, when preparing the modified adhesive, in step S1, the reinforcing material is composed of a mixture of nano-reinforced fillers and metal oxides, and the remaining steps and raw materials are the same as those in Example 3;

[0137] S1: According to the mass ratio of the reinforcing material, 3-glycidyloxypropyltriethoxysilane, and the ethanol and water mixed solution being 5.2:1.2:90, the reinforcing material and 3-glycidyloxypropyltriethoxysilane were added to the ethanol and water mixed solution (the volume ratio of ethanol and water was 9:1), and then ultrasonically treated for 35 minutes (ultrasonic power of 100 W, ultrasonic frequency of 40 kHz), and then stirred at 65°C for 22 hours. After filtering, washing with ethanol three times (the mass of ethanol each time was 20% of the mass of the ethanol and water mixed solution), and finally vacuum dried at 65°C for 48 hours, a silane reinforced material was obtained, wherein the reinforcing material was composed of a nano-reinforced filler and a metal oxide mixed in a mass ratio of 1:1; the nano-reinforced filler was composed of a mixture of graphene oxide and halloysite nanotubes in a mass ratio of 0.9:0.6; and the metal oxide was composed of a mixture of nano-molybdenum oxide, nano-cerium oxide and nano-manganese dioxide in a mass ratio of 0.8:0.4:0.2.

[0138] Comparative Example 7

[0139] The difference between this comparative example and Example 3 is that, when preparing the modified adhesive, the mass of the composite adhesive in step S2 is replaced by polyvinyl alcohol, and the remaining steps and raw materials are the same as those in Example 3;

[0140] S2: According to the mass ratio of polyvinyl alcohol, deionized water and silane reinforcing material of 10.2:120:0.6, polyvinyl alcohol was added to deionized water and stirred at 95°C for 1.5 hours. Then, the silane reinforcing material in step S1 was added and stirred at 95°C for 0.5 hours to obtain a gel solution. The gel solution was further stirred at 95°C for 5.5 hours. After the end, it was cooled to room temperature, filtered, and finally dried at room temperature for 24 hours to obtain a modified adhesive.

[0141] Comparative Example 8

[0142] The difference between this comparative example and Example 3 is that, when preparing the modified adhesive, the mass of the composite adhesive in step S2 is replaced by lignin amino polyol, and the remaining steps and raw materials are the same as those in Example 3;

[0143] S2: According to the mass ratio of lignin amino polyol, deionized water and silane reinforcing material of 10.2:120:0.6, lignin amino polyol was added to deionized water and stirred at 95°C for 1.5 hours. Then, the silane reinforcing material in step S1 was added and stirred at 95°C for 0.5 hours to obtain a gel solution. The gel solution was further stirred at 95°C for 5.5 hours. After the end, it was cooled to room temperature, filtered, and finally dried at room temperature for 24 hours to obtain a modified adhesive.

[0144] Comparative Example 9

[0145] The difference between this comparative example and Example 3 is that when preparing the homoanhydride catalyst, the mass of vanadium pentoxide nanowires is replaced by vanadium pentoxide, and the remaining steps and raw materials are the same as those in Example 3;

[0146] A homogeneous 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;

[0147] 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 parts of lanthanum oxide and 15 parts of deionized water;

[0148] The lower layer 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;

[0149] 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.

[0150] The inert carrier is a hollow cylindrical ceramic ring with the following specifications: outer diameter × height × thickness: 7.5 mm × 6 mm × 2 mm;

[0151] A1: Preparation of upper catalyst A:

[0152] Weigh parts of raw materials by mass, mix vanadium pentoxide, composite nano-titanium dioxide, lanthanum oxide and deionized water, and then ball mill for 7 hours at a ball milling speed of 300 rpm. Use zirconia balls as 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 a modified binder and stir at a speed of 500 rpm for 5 minutes to obtain an upper layer of active component A. Weigh an inert carrier and place it in a rotary drum (the mass of the inert carrier accounts for 37.5% of the production capacity of the rotary drum). Then heat it to 85°C, evenly spray the upper layer of active component A on the surface of the inert carrier, and heat the drum while rotating (the drum rotates at a speed of 30 rpm) until the coating is completely dried to obtain an upper layer of catalyst A.

[0153] A2: Preparation of lower layer catalyst B:

[0154] Weigh parts by mass of raw materials, mix vanadium pentoxide, composite nano-titanium dioxide, lanthanum oxide and deionized water, and then ball mill for 7 hours at a ball milling speed of 300 rpm. Use zirconia balls as 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 a modified binder and stir at a speed of 500 rpm for 5 minutes to obtain a lower layer of active component B. Weigh an inert carrier and place it in a rotary drum (the mass of the inert carrier accounts for 37.5% of the production capacity of the rotary drum). Then heat it to 85°C, evenly spray the lower layer of active component B on the surface of the inert carrier, and heat the drum while rotating (the drum rotates at a speed of 30 rpm) until the coating is completely dried to obtain a lower layer of catalyst B.

[0155] A3: Repackaging:

[0156] The upper layer catalyst A in step A1 and the lower layer catalyst B in step A2 are packaged separately to finally obtain a homogeneous anhydride catalyst.

[0157] The yield of the anhydride catalysts prepared in Examples 1-3 and Comparative Examples 1-9 was determined. The above catalysts were used to carry out an oxidation reaction of durene to produce anhydride. The specific performance evaluation steps were as follows:

[0158] (1) Loading:

[0159] According to the mass ratio of the lower layer catalyst B to the upper layer catalyst A of 5:4, the lower layer catalyst B in step A2 was first loaded into a single tube test device (the reactor tube had an inner diameter of 25 mm and a height of 4000 mm), and then the upper layer catalyst A in step A1 was loaded, without any other inert carrier in between. The total loading height was controlled to account for 70% of the height of the single tube, with the lower layer catalyst B accounting for 50% of the total loading height and the upper layer catalyst A accounting for 50% of the total loading height, to obtain a loaded homogenized anhydride catalyst;

[0160] (2) Activation:

[0161] The loaded anhydride catalyst in step (1) was activated by introducing air at a flow rate of 1000 NL / h, controlling the heating rate to be 7°C / h, then heating to 400°C, maintaining the temperature for 30 hours, and then cooling to 380°C to complete the activation, thereby obtaining an activated anhydride catalyst;

[0162] (3) Reaction:

[0163] After being vaporized by a vaporizer, durenyl is mixed with air and introduced into a single-tube test device containing the activated anhydride catalyst in step (2), and then the reaction is started. After the reaction is completed, the anhydride yield is measured. The reaction conditions are: the air volume is 5Nm 3 / h, the reaction temperature was 370°C, and the durene load was 70 g / h.

[0164] The measurement results are shown in Table 1 below:

[0165] Table 1 Test results of the anhydride catalysts prepared in Examples 1-3 and Comparative Examples 1-9

[0166]

[0167] As can be seen from the data in Table 1 above, by comparing Comparative Examples 1-6 with Example 3, the mass of the nano-reinforced filler in step S1 is replaced by graphene oxide or halloysite nanotubes, or the metal oxide is composed of a mixture of nano-molybdenum oxide and nano-cerium oxide, or the metal oxide is composed of a mixture of nano-molybdenum oxide and nano-manganese dioxide, or the metal oxide is composed of a mixture of nano-cerium oxide and nano-manganese dioxide, or the reinforcing material is composed of a mixture of nano-reinforced filler and metal oxide, and finally the homogenized anhydride catalyst is prepared. The test results are worse than those in Example 3, indicating that the nano-reinforced filler composed of a mixture of graphene oxide and halloysite nanotubes is , the two have a synergistic effect, can effectively improve the catalytic efficiency and selectivity of the anhydride catalyst, improve the contact efficiency between the reactants and the active sites, and increase the anhydride yield; the metal oxide composed of a mixture of nano-molybdenum oxide, nano-cerium oxide and nano-manganese dioxide has a synergistic effect, can effectively improve the catalytic performance of the catalyst, and further enhance the catalytic activity of the catalyst, and increase the anhydride yield; loading the metal oxide on the surface of the nano-reinforced 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 improve the catalytic efficiency, and increase the anhydride yield;

[0168] By comparing Comparative Examples 7-9 with Example 3, it can be seen that the mass of the composite binder in step S2 is replaced by polyvinyl alcohol or lignin amino polyol, or the mass of vanadium pentoxide nanowires is replaced by vanadium pentoxide, and finally the anhydride catalyst is prepared. The test results are worse than those in Example 3, indicating that the composite binder composed of a mixture of polyvinyl alcohol and lignin amino polyol has a synergistic effect, which can better improve the adhesion of the coating on the carrier, enhance the interfacial bonding between the active component and the carrier, and enhance the mechanical strength and thermal stability of the catalyst, further improving the anhydride yield; the anhydride catalyst is prepared using vanadium pentoxide nanowires, which have a high specific surface area, can expose more active sites, effectively improve the catalytic activity of the catalyst, and further increase the anhydride yield.

[0169] As can be seen from Table 1 above, the average anhydride catalysts prepared in Examples 1-3 are compared with the average anhydride catalysts prepared in Comparative Examples 1-9. A reinforcing material is prepared by loading a metal oxide on a nano-reinforced filler, and then combining the reinforcing material with a silane coupling agent, and then combining it with a composite binder to obtain a modified adhesive; vanadium pentoxide nanowires, composite nano-titanium dioxide, a modified adhesive, an additive, and deionized water are mixed, ball-milled, and then coated on the surface of an inert carrier to obtain an average anhydride catalyst, which meets the test performance requirements. The average anhydride catalysts prepared in Comparative Examples 1-9 did not meet the performance requirements. This shows that the average 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 average anhydride yield, and extend the service life of the catalyst, and have good comprehensive performance.

[0170] Throughout the specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0171] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the invention or exceed the scope defined by the present invention, they should all fall within the scope of protection of the present invention.

Claims

1. A homoanhydride 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 comprises the following raw materials in parts by weight: 0.5-1 parts of vanadium pentoxide nanowires, 2-3 parts of composite nano-titanium dioxide, 2.5-3.5 parts of modified binder, 0.04-0.08 parts of auxiliary agent and 10-15 parts of deionized water; The lower layer catalyst B comprises the following raw materials in parts by weight: 0.5-1 parts of vanadium pentoxide nanowires, 2-3 parts of composite nano-titanium dioxide, 2.5-3.5 parts of modified binder, 0.06-0.1 parts of auxiliary agent and 10-15 parts of deionized water; The preparation method of the modified adhesive comprises the following steps: S1: Silane-reinforced material is obtained by combining the reinforcing material with the silane coupling agent; S2: combining the silane reinforcement material in step S1 with a composite adhesive to obtain a modified adhesive; The reinforcing material is prepared by loading metal oxides with nano-reinforced fillers; The nano-reinforced filler is composed of a mixture of graphene oxide and halloysite nanotubes 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 amino polyol mixed in a mass ratio of 0.6-0.7:0.4-0.5; The preparation method of the lignin amination polyol comprises the following steps: Alkali lignin, deionized water, diethanolamine and diisopropanolamine are mixed evenly, then heated to 75-85°C, and then formaldehyde solution is added. The pH value of the system is adjusted to 11.5-12.5 with sodium hydroxide solution, and then stirred for reaction for 1.5-2.5 hours. After the reaction is completed, sulfuric acid solution is used for precipitation, filtered, washed with deionized water, and finally vacuum dried at 45-55°C to obtain lignin amino polyol; 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.

2. A homogenous anhydride catalyst according to claim 1, characterized in that, Step S1 is specifically as follows: The reinforcing material and the silane coupling agent are added to a mixed solution of ethanol and water, and then ultrasonically treated for 25-35 minutes, stirred at 55-65° C. for 22-24 hours, filtered, washed with ethanol, and finally vacuum dried at 55-65° C. to obtain a silane reinforced material.

3. A homogenous anhydride catalyst according to claim 2, characterized in that, The preparation method of the reinforcing material comprises the following steps: The nano-reinforced filler is added to deionized water and treated in an ultrasonic bath for 1.5-2.5 hours, and then the metal oxide is added and treated in an ultrasonic bath for 1.5-2.5 hours. After the treatment, the mixture is stirred at 25-35° C. for 1.5-2.5 hours and finally vacuum dried at 90-100° C. to obtain a reinforced material.

4. A homogenous anhydride catalyst according to claim 1, characterized in that: Step S2 is specifically as follows: The composite adhesive is added to deionized water and stirred at 85-95° C. for 1.5-2.5 hours. The silane reinforcing material in step S1 is then added and stirred at 85-95° C. for 0.5-1.5 hours to obtain a gel solution. The gel solution is further stirred at 85-95° C. for 5.5-6.5 hours. After the stirring, the solution is cooled to room temperature, filtered, and finally dried at room temperature to obtain a modified adhesive.

5. A method for preparing the homogenized anhydride catalyst according to any one of claims 1 to 4, characterized in that: The following steps are involved: A1: Preparation of upper catalyst A: Weigh parts by mass of raw materials, mix vanadium pentoxide nanowires, composite nano-titanium dioxide, additives, and deionized water, and then ball-mill. After the ball-milling is completed, add a modified binder and stir for 5-10 minutes to obtain an upper layer of 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 layer of active component A onto the surface of the inert carrier. The drum is rotated and heated until the coating is completely dried to obtain an upper layer of catalyst A. A2: Preparation of lower layer catalyst B: Weigh parts of raw materials by mass, mix vanadium pentoxide nanowires, composite nano-titanium dioxide, additives, and deionized water, and then ball-mill. After the ball-milling is completed, add a modified binder and stir for 5-10 minutes to obtain a lower layer of 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 layer of active component B on the surface of the inert carrier. The drum is rotated and heated until the coating is completely dried to obtain a lower layer of catalyst B. A3: Repackaging: The upper layer catalyst A in step A1 and the lower layer catalyst B in step A2 are packaged separately to finally obtain a homogeneous anhydride catalyst.

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