Vanadium-titanium-phosphorus oxide catalyst prepared from ionic liquid aid as well as preparation method and application of vanadium-titanium-phosphorus oxide catalyst

Abstract

The invention provides a vanadium-titanium-phosphorus oxide catalyst prepared from an ionic liquid additive as well as a preparation method and application of the vanadium-titanium-phosphorus oxide catalyst, and belongs to the technical field of catalyst preparation. The preparation method comprises the following steps: fully and uniformly mixing an ionic liquid aqueous solution, respectively dipping the ionic liquid aqueous solution and an active component on a carrier, and drying and calcining after dipping to obtain the supported composite metal oxide catalyst. The catalyst provided by the invention is simple in preparation process and low in cost, and when the catalyst is applied to production of pyromellitic dianhydride from durene, the characteristics of high space velocity, high activity, short residence time, small catalyst dosage, simple reaction, one-step realization and the like can be realized. The catalyst has excellent catalytic performance in durene oxidation reaction, and is suitable for industrial application.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, and in particular to a vanadium-titanium phosphorus-oxygen catalyst prepared with an ionic liquid promoter, its preparation method, and its application. Background Technology

[0002] Pyromellitic dianhydride (PMDA) is an important chemical raw material. Pyromellitic dianhydride and its derivatives have a wide range of applications, primarily as monomers for heat-resistant resins such as polyimide and pyrrolidone, plasticizers, epoxy resin curing agents, pharmaceutical intermediates, powder coating matting agent intermediates, and modifiers for alkyd resins and polyester resins. Among these applications, polyimide, known in the materials field as a high-temperature resistant "universal plastic," is the largest application of pyromellitic dianhydride. This polymer has important applications in films, fibers, adhesives, enameled wire coatings, and laminates, and products made from it are widely used in the aerospace, nuclear materials, and electronics industries.

[0003] In 1947, the California Research Corp. in the United States first used mesitylene as a raw material to produce homogeneous anhydride through gas-phase catalytic oxidation with a V2O5 composite oxide catalyst. This method has now become the main method for industrial production of homogeneous anhydride.

[0004] Patent CN109336900A discloses a method for preparing pyromellitic dianhydride based on a modified vanadium-titanium oxide composite catalyst. In this method, sodium metavanadate and tetrabutyl titanate are used as raw materials, and a modified vanadium-titanium catalyst is prepared by in-situ modification. Mesitylene is used as a raw material; it is heated and melted, then filtered and fed into a metering tank. Steam is passed through an inner coil to maintain the temperature at 100-105°C, and the mixture is then filtered and pumped into a vaporization mixer. Air is preheated to 190-200°C and then enters the vaporization mixer. The preheated air reacts with the mesitylene under the catalysis of the prepared composite catalyst. The resulting gas is cooled by heat exchanger to obtain crude pyromellitic dianhydride. Then, it is recrystallized with acetone to obtain the final pyromellitic dianhydride. This method yields a high dianhydride yield, but the catalyst preparation process is relatively cumbersome.

[0005] Patent CN108043435A discloses a catalyst for the gas-phase oxidation of mesitylene to prepare pyromellitic dianhydride, as well as its preparation and application. In this method, the catalyst consists of an inert support and an active component loaded thereon. Titanium dioxide, ammonium metavanadate, potassium nitrate, and niobium pentoxide are added to an oxalic acid solution at 70-90°C to prepare a suspension, which is then refluxed and stirred for 12-24 hours. Then, α-Ti(HPO4)2·H2O is added to the suspension, and the mixture is refluxed and stirred for 12-24 hours. Polyvinyl acetate is then added to the suspension, and emulsification is carried out using a homogenizing pump. The suspension is sprayed onto the inert support at 150-300°C, and spraying is stopped when the active component accounts for 5-20% of the total mass of the catalyst. The obtained catalyst is then calcined in a furnace at 400-550°C to obtain the target catalyst. In this method, although the introduction of titanium phosphate effectively adjusts the number and ratio of acid-base centers in the catalyst, the preparation of titanium phosphate requires the use of concentrated hydrochloric acid, which poses certain operational risks. In addition, the catalyst preparation process is also quite complicated.

[0006] The methods described above, addressing the low product yield and selectivity of the gas-phase oxidation of mesitylene to produce pyromellitic dianhydride, all utilize composite catalysts primarily composed of V₂O₅-TiO₂ and supplemented by other metal oxides. The gas-phase production of pyromellitic dianhydride from mesitylene involves high oxidation temperatures, numerous side reactions, and relatively low product purity, selectivity, and yield. Therefore, developing a catalyst capable of improving the yield and selectivity of pyromellitic dianhydride is of great significance. Summary of the Invention

[0007] The purpose of this invention is to provide a vanadium-titanium phosphorus-oxygen catalyst prepared with ionic liquid additives, its preparation method and application, in order to solve the above-mentioned technical problems.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a vanadium-titanium phosphorus-oxygen catalyst prepared with an ionic liquid additive, wherein the vanadium-titanium phosphorus-oxygen catalyst comprises a support and an active component supported on the support, and an ionic liquid; The active component includes a vanadium source; the ionic liquid is a P-containing ionic liquid and / or a B-containing ionic liquid. The active component has a mass content of 0.01-40% of the vanadium-titanium-phosphorus-oxygen catalyst, and the ionic liquid has a mass content of 0.01-40% of the support.

[0009] Furthermore, the P-containing ionic liquid comprises one or more of [EMIM][PF6], [EMIM][DHP], [EMIM][DEP], [N1111][PF6], [Epy][PF6], [P4444]Cl, [P4444][PF6], [PMIM][DHP], and [EMIM][DMP]; the B-containing ionic liquid comprises one or more of [EMIM][BF4], [Epy][BF4], [N222][BF4], [EMPyrr][BF4], and [HOEMIM][BF4].

[0010] Furthermore, the vanadium source comprises vanadium pentoxide and / or ammonium metavanadate; The carrier is titanium dioxide, and the titanium dioxide has anatase and / or rutile crystal forms.

[0011] This invention also provides a method for preparing the above-mentioned vanadium-titanium phosphorus-oxygen catalyst, comprising the following steps: 1) The active component is added to an oxalic acid solution to react and obtain the first impregnation solution; the ionic liquid is dissolved in water to obtain the second impregnation solution; 2) The carrier is sequentially immersed in the first impregnation solution and the second impregnation solution. After impregnation, excess water is removed, and then the carrier is dried and calcined in sequence to obtain the vanadium-titanium-phosphorus-oxygen catalyst.

[0012] Furthermore, in step 1), the reaction temperature is 70~90℃; the concentration of oxalic acid solution is 0.1~0.5g / mL; and the mass ratio of active component to oxalic acid is 1:1~3.

[0013] Furthermore, the drying temperature is 100~120℃, and the drying time is 10~20h.

[0014] Furthermore, the calcination temperature is 300~800℃, and the calcination time is 2~5h.

[0015] The present invention also provides the application of the above-mentioned vanadium-titanium phosphorus-oxygen catalyst in the catalytic production of homohydric anhydride by mesitylene, wherein the catalytic production of homohydric anhydride is carried out in a reactor, which is a fixed-bed reactor, a moving-bed reactor, or a fluidized-bed reactor.

[0016] The beneficial effects of this invention are: 1. The catalyst prepared by the method of the present invention has a simple preparation process and low cost.

[0017] 2. The catalyst prepared by the method of this invention has the advantages of high conversion rate (maximum conversion rate of 100%), high mass yield (maximum yield of 128%), and high selectivity in the production of homogeneous anhydride from mesitylene. It also has a high space velocity (up to 8000 h⁻¹). -1It features short residence time, low catalyst dosage, and simple one-step reaction.

[0018] 3. The performance of the catalyst prepared by the method of the present invention was evaluated. It was found that the catalyst has the advantages of good stability, reusability and no loss during the production of homogenized anhydride. The reusability time exceeds 300 hours and the number of reuses reaches 50 times. At the same time, although the catalyst activity fluctuates slightly during the reusability period, the change is not significant. Therefore, it is suitable for industrial applications.

[0019] 4. Using the catalyst prepared by the method of this invention to produce homohydric anhydride from mesitylene can reduce corrosion of equipment, reduce economic costs, and achieve the goal of high-efficiency production of homohydric anhydride. The ionic liquid modified vanadium-titanium phosphorus-oxygen catalyst of this invention can be applied to ordinary fixed-bed reactors and has good stability, which is conducive to the industrial application of mesitylene to homohydric anhydride. Detailed Implementation

[0020] This invention provides a vanadium-titanium phosphorus-oxygen catalyst prepared with an ionic liquid additive, wherein the vanadium-titanium phosphorus-oxygen catalyst comprises a support and an active component supported on the support, and an ionic liquid; The active component includes a vanadium source; the ionic liquid is a P-containing ionic liquid and / or a B-containing ionic liquid. The active component has a mass content of 0.01-40% of the vanadium-titanium-phosphorus-oxygen catalyst, and the ionic liquid has a mass content of 0.01-40% of the support.

[0021] In this invention, the mass content of the active component is 5-40% of the mass of the vanadium-titanium-phosphorus-oxygen catalyst, preferably 10-40%, and more preferably 20-30%.

[0022] In this invention, the mass content of the ionic liquid is 1-40% of the carrier, preferably 10-40%, and more preferably 20-30%.

[0023] In this invention, the P-containing ionic liquid comprises one or more of [EMIM][PF6], [EMIM][DHP], [EMIM][DEP], [N1111][PF6], [Epy][PF6], [P4444]Cl, [P4444][PF6], [PMIM][DHP], and [EMIM][DMP], preferably [EMIM][DEP] and / or [EMIM][DHP]; the B-containing ionic liquid comprises one or more of [EMIM][BF4], [Epy][BF4], [N222][BF4], [EMPyrr][BF4], and [HOEMIM][BF4], preferably [EMIM][BF4].

[0024] In this invention, the vanadium source comprises vanadium pentoxide and / or ammonium metavanadate, preferably vanadium pentoxide; The carrier is titanium dioxide, and the crystal form of titanium dioxide is anatase and / or rutile, preferably a mixed crystal form of anatase and rutile.

[0025] This invention also provides a method for preparing the above-mentioned vanadium-titanium phosphorus-oxygen catalyst, comprising the following steps: 1) The active component is added to an oxalic acid solution to react and obtain the first impregnation solution; the ionic liquid is dissolved in water to obtain the second impregnation solution; 2) The carrier is sequentially immersed in the first impregnation solution and the second impregnation solution. After impregnation, excess water is removed, and then the carrier is dried and calcined in sequence to obtain the vanadium-titanium-phosphorus-oxygen catalyst.

[0026] In this invention, in step 1), the reaction temperature is 70~90℃, preferably 80℃; the concentration of the oxalic acid solution is 0.1~0.5g / mL, preferably 0.25~0.3g / mL; the mass ratio of the active component to oxalic acid is 1:1~3, preferably 1:1.2~2.1, and more preferably 1:1.5~2.1.

[0027] In this invention, the impregnation is either an equal volume impregnation of the ionic liquid and the active component, or an excessive impregnation of the ionic liquid or the excessive impregnation of the active component.

[0028] In this invention, the drying temperature is 100~120℃, preferably 110~120℃; the drying time is 10~20h, preferably 12h.

[0029] In this invention, the calcination temperature is 300~800℃, preferably 450~550℃, more preferably 480~520℃, and even more preferably 500℃; the calcination time is 2~5h, preferably 3~4h.

[0030] In this invention, the calcination is carried out in an air or nitrogen atmosphere.

[0031] The present invention also provides the application of the above-mentioned vanadium-titanium phosphorus-oxygen catalyst in the catalytic production of homohydric anhydride by mesitylene, wherein the catalytic production of homohydric anhydride is carried out in a reactor, which is a fixed-bed reactor, a moving-bed reactor, or a fluidized-bed reactor.

[0032] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0033] Example 1

[0034] Preparation of catalysts for the production of homogeneous anhydride from mesitylene: Add 5g of oxalic acid to 30mL of deionized water and stir at 80℃ until completely dissolved. Then add 2.40g of vanadium pentoxide and react fully. Add 6.32g of titanium dioxide and dissolve 1.34g of [EMIM][PF6] in 20mL of water. Add the solution to the stirred impregnation container for impregnation. After removing excess water by evaporation, dry at 120℃ for 12h and then calcine in a muffle furnace at 450℃ for 3h to obtain the catalyst.

[0035] Catalysis of mesitylene to produce homohydric anhydride: 20 mL of catalyst was added to a micro fixed-bed reactor to carry out the reaction of mesitylene to homohydric anhydride. The reaction temperature was 400 °C and the reaction space velocity was 6000 h⁻¹. -1 Mesitylene loading: 14 g / m 3 Samples were taken and analyzed after 2 hours. The experimental results are shown in Table 1. The results show that the mass yield of homotoluene produced by the catalyst prepared in this example was 112%, and the purity of homotoluene was 96%.

[0036] Example 2

[0037] Preparation of catalysts for the production of homogeneous anhydride from mesitylene: Add 5g of oxalic acid to 20mL of deionized water and stir at 80℃ until completely dissolved. Then add 2.40g of vanadium pentoxide and react fully. Add 6.32g of titanium dioxide and dissolve 1.45g of [EMIM][DHP] in 20mL of water. Add the solution to the stirred impregnation container for impregnation. After removing excess water by evaporation, dry at 120℃ for 12h and then calcine in a muffle furnace at 500℃ for 3h to obtain the catalyst.

[0038] Catalysis of mesitylene to produce homohydric anhydride: 20 mL of catalyst was added to a micro fixed-bed reactor to carry out the reaction of mesitylene to homohydric anhydride. The reaction temperature was 420 °C and the reaction space velocity was 6000 h⁻¹. -1 Mesitylene loading: 14 g / m 3 Samples were taken and analyzed after 2 hours. The experimental results are shown in Table 1. The results show that the mass yield of homotoluene produced by the catalyst prepared in this example was 118%, and the purity of homotoluene was 98%.

[0039] Example 3

[0040] Preparation of catalysts for the production of homogeneous anhydride from mesitylene: Add 5g of oxalic acid to 20mL of deionized water and stir at 80℃ until completely dissolved. Then add 2.40g of vanadium pentoxide and react fully. Add 6.32g of titanium dioxide and dissolve 1.39g of [EMIM][DEP] in 20mL of water. Add the solution to the stirred impregnation container for impregnation. After removing excess water by evaporation, dry at 120℃ for 12h and then calcine in a muffle furnace at 550℃ for 3h to obtain the catalyst.

[0041] Catalysis of mesitylene to produce homohydric anhydride: 20 mL of catalyst was added to a micro fixed-bed reactor to carry out the reaction of mesitylene to homohydric anhydride. The reaction temperature was 430 °C and the reaction space velocity was 6000 h⁻¹. -1 Mesitylene loading: 14 g / m 3 Samples were taken and analyzed after 2 hours. The experimental results are shown in Table 1. The results show that the mass yield of homotoluene produced by the catalyst prepared in this example is 115%, and the purity of homotoluene is 98%.

[0042] Example 4

[0043] Preparation of catalysts for the production of homogeneous anhydride from mesitylene: Add 5g of oxalic acid to 20mL of deionized water and stir at 80℃ until completely dissolved. Then add 2.40g of vanadium pentoxide and react fully. Add 5.60g of titanium dioxide. Dissolve 1.15g of [EMIM][BF4] in 20mL of water and add it to the stirred impregnation container for impregnation. After removing excess water by evaporation, dry at 120℃ for 12h and then calcine in a muffle furnace at 550℃ for 3h to obtain the catalyst.

[0044] Catalysis of mesitylene to produce homohydric anhydride: 20 mL of catalyst was added to a micro fixed-bed reactor to carry out the reaction of mesitylene to homohydric anhydride. The reaction temperature was 430 °C and the reaction space velocity was 3000 h⁻¹. -1 Mesitylene loading: 14 g / m 3 Samples were taken and analyzed after 2 hours. The experimental results are shown in Table 1. The results show that the mass yield of homotoluene produced by the catalyst prepared in this example was 102%, and the purity of homotoluene was 96%.

[0045] Example 5

[0046] Preparation of catalysts for the production of homogeneous anhydride from mesitylene: Add 5g of oxalic acid to 20mL of deionized water and stir at 80℃ until completely dissolved. Then add 2.40g of vanadium pentoxide and react fully. Add 6.32g of titanium dioxide. Dissolve 0.75g of [N222][BF4] in 20mL of water and add it to the stirred impregnation container for impregnation. After removing excess water by evaporation, dry at 120℃ for 12h and then calcine in a muffle furnace at 500℃ for 3h to obtain the catalyst.

[0047] Catalysis of mesitylene to produce homohydric anhydride: 20 mL of catalyst was added to a micro fixed-bed reactor to carry out the reaction of mesitylene to homohydric anhydride. The reaction temperature was 440 °C and the reaction space velocity was 8000 h⁻¹. -1 Mesitylene loading: 14 g / m 3 Samples were taken and analyzed after 2 hours. The experimental results are shown in Table 1. The results show that the catalyst prepared in this example can be used to catalyze the production of homohydric anhydride from mesitylene with a yield of 99% and a purity of 97%.

[0048] Example 6

[0049] Preparation of catalysts for the production of homogeneous anhydride from mesitylene: Add 5g of oxalic acid to 20mL of deionized water and stir at 80℃ until completely dissolved. Then add 2.40g of vanadium pentoxide and react fully. Add 9.48g of titanium dioxide and dissolve 0.51g of [Epy][BF4] in 20mL of water. Add the solution to the stirred impregnation container for impregnation. After removing excess water by evaporation, dry at 120℃ for 12h and then calcine in a muffle furnace at 500℃ for 3h to obtain the catalyst.

[0050] Catalysis of mesitylene to produce homohydric anhydride: 20 mL of catalyst was added to a micro fixed-bed reactor to carry out the reaction of mesitylene to homohydric anhydride. The reaction temperature was 430 °C and the reaction space velocity was 6000 h⁻¹. -1 Mesitylene loading: 14 g / m 3 Samples were taken and analyzed after 2 hours. The experimental results are shown in Table 1. The results show that the mass yield of homotoluene produced by the catalyst prepared in this example is 98%, and the purity of homotoluene is 97%.

[0051] Example 7

[0052] Preparation of catalysts for the production of homogeneous anhydride from mesitylene: Add 5g of oxalic acid to 20mL of deionized water and stir at 80℃ until completely dissolved. Then add 2.40g of vanadium pentoxide and react fully. Add 9.48g of titanium dioxide. Dissolve 1.21g of [EMIM][PF6] and 0.85g of [N222][BF4] in 20mL of water and add the solution to the stirred impregnation container for impregnation. After removing excess water by evaporation, dry at 120℃ for 12h and then calcine in a muffle furnace at 500℃ for 3h to obtain the catalyst.

[0053] Catalysis of mesitylene to produce homohydric anhydride: 20 mL of catalyst was added to a micro fixed-bed reactor to carry out the reaction of mesitylene to homohydric anhydride. The reaction temperature was 430 °C and the reaction space velocity was 8000 h⁻¹. -1 Mesitylene loading: 14 g / m 3 Samples were taken and analyzed after 2 hours. The experimental results are shown in Table 1. The results show that the mass yield of homotoluene produced by the catalyst prepared in this example is 125%, and the purity of homotoluene is 98%.

[0054] Example 8

[0055] Preparation of catalysts for the production of homogeneous anhydride from mesitylene: Add 5g of oxalic acid to 20mL of deionized water and stir at 80℃ until completely dissolved. Then add 2.40g of vanadium pentoxide and react fully. Add 6.32g of titanium dioxide. Dissolve 1.36g of [EMIM][DEP] and 0.52g of [EMIM][BF4] in 20mL of water and add the solution to the stirred impregnation container for impregnation. After removing excess water by evaporation, dry at 120℃ for 12h and then calcine at 500℃ for 3h in a muffle furnace to obtain the catalyst.

[0056] Catalysis of mesitylene to produce homohydric anhydride: The production of homohydric anhydride from mesitylene was carried out in a micro fixed-bed reactor with 20 mL of catalyst at a reaction temperature of 440 °C and a reaction space velocity of 6000 h⁻¹. -1 Mesitylene loading: 14 g / m 3 Samples were taken and analyzed after 2 hours. The experimental results are shown in Table 1. The results show that the mass yield of homotoluene produced by the catalyst prepared in this example was 128%, and the purity of homotoluene was 97%.

[0057] Example 9

[0058] Preparation of catalysts for the production of homogeneous anhydride from mesitylene: Add 5g of oxalic acid to 20mL of deionized water and stir at 80℃ until completely dissolved. Then add 2.40g of vanadium pentoxide and react fully. Add 6.32g of titanium dioxide. Dissolve 1.56g of [P4444]Cl and 0.27g of [EMPyrr][BF4] in 20mL of water and add the solution to the stirred impregnation container for impregnation. After removing excess water by evaporation, dry at 120℃ for 12h and then calcine in a muffle furnace at 500℃ for 3h to obtain the catalyst.

[0059] Catalysis of mesitylene to produce homohydric anhydride: 20 mL of catalyst was added to a micro fixed-bed reactor to carry out the reaction of mesitylene to homohydric anhydride. The reaction temperature was 420 °C and the reaction space velocity was 6000 h⁻¹. -1 Mesitylene loading: 14 g / m 3 Samples were taken and analyzed after 2 hours. The experimental results are shown in Table 1. The results show that the mass yield of homotoluene produced by the catalyst prepared in this example was 122%, and the purity of homotoluene was 98%.

[0060] Example 10

[0061] Preparation of catalysts for the production of homogeneous anhydride from mesitylene: Add 5g of oxalic acid to 20mL of deionized water and stir at 80℃ until completely dissolved. Then add 2.40g of vanadium pentoxide and react fully. Add 6.32g of titanium dioxide. Dissolve 1.61g of [P4444][PF6] and 0.28g of [HOEMIM][BF4] in 20mL of water and add the solution to a stirred impregnation container for impregnation. After removing excess water by evaporation, dry at 120℃ for 12h and then calcine in a muffle furnace at 500℃ for 3h to obtain the catalyst.

[0062] Catalysis of mesitylene to produce homohydric anhydride: 20 mL of catalyst was added to a micro fixed-bed reactor to carry out the reaction of mesitylene to homohydric anhydride. The reaction temperature was 420 °C and the reaction space velocity was 8000 h⁻¹. -1 Mesitylene loading: 14 g / m 3 Samples were taken and analyzed after 2 hours. The experimental results are shown in Table 1. The results show that the mass yield of homotoluene produced by the catalyst prepared in this example was 124%, and the purity of homotoluene was 97%.

[0063] Example 11

[0064] Preparation of catalysts for the production of homogeneous anhydride from mesitylene: Add 5g of oxalic acid to 20mL of deionized water and stir at 80℃ until completely dissolved. Then add 2.40g of vanadium pentoxide and react fully. Add 6.32g of titanium dioxide and dissolve 1.76g of [PMIM][DHP] in 20mL of water. Add the solution to the stirred impregnation container for impregnation. After removing excess water by evaporation, dry at 120℃ for 12h and then calcine in a muffle furnace at 500℃ for 3h to obtain the catalyst.

[0065] Catalysis of mesitylene to produce homohydric anhydride: 20 mL of catalyst was added to a micro fixed-bed reactor to carry out the reaction of mesitylene to homohydric anhydride. The reaction temperature was 430 °C and the reaction space velocity was 6000 h⁻¹. -1 Mesitylene loading: 14 g / m 3 Samples were taken and analyzed after 2 hours. The experimental results are shown in Table 1. The results show that the mass yield of homotoluene produced by the catalyst prepared in this example was 116%, and the purity of homotoluene was 98%.

[0066] Example 12

[0067] Preparation of catalysts for the production of homogeneous anhydride from mesitylene: Add 5g of oxalic acid to 20mL of deionized water and stir at 80℃ until completely dissolved. Then add 2.40g of vanadium pentoxide and react fully. Add 6.32g of titanium dioxide and dissolve 1.87g of [EMIM][DMP] in 20mL of water. Add the solution to the stirred impregnation container for impregnation. After removing excess water by evaporation, dry at 120℃ for 12h and then calcine in a muffle furnace at 500℃ for 3h to obtain the catalyst.

[0068] Catalysis of mesitylene to produce homohydric anhydride: The production of homohydric anhydride from mesitylene was carried out in a micro fixed-bed reactor with 20 mL of catalyst at a reaction temperature of 440 °C and a reaction space velocity of 6000 h⁻¹. -1 Mesitylene loading: 14 g / m 3 Samples were taken and analyzed after 2 hours. The experimental results are shown in Table 1. The results show that the mass yield of homotoluene produced by the catalyst prepared in this example was 114%, and the purity of homotoluene was 96%.

[0069] Comparative Example 1

[0070] Preparation of catalysts for the production of homogeneous anhydride from mesitylene: Add 5g of oxalic acid to 20mL of deionized water and stir at 80℃ until completely dissolved. Then add 2.40g of vanadium pentoxide and react fully. Add 6.32g of titanium dioxide, evaporate excess water, dry at 120℃ for 12h, and then calcine in a muffle furnace at 450℃ for 3h to obtain the catalyst.

[0071] Catalysis of mesitylene to produce homohydric anhydride: The production of homohydric anhydride from mesitylene was carried out in a micro fixed-bed reactor with 20 mL of catalyst at a reaction temperature of 440 °C and a reaction space velocity of 6000 h⁻¹. -1 Mesitylene loading: 14 g / m 3 Samples were taken and analyzed after 2 hours. The experimental results are shown in Table 1. The results show that the mass yield of homotoluene produced by the catalyst prepared in this example is 83%, and the purity of homotoluene is 93%.

[0072] Table 1 Results of different catalysts in the production of homohydric anhydride from mesitylene.

[0073] As can be seen from the above embodiments, the present invention provides a vanadium-titanium phosphorus-oxygen catalyst prepared with an ionic liquid as an additive, its preparation method, and its application. The present invention uses an ionic liquid as an additive, impregnating it onto a support via an impregnation method. First, the active component is impregnated, then the ionic liquid is impregnated. After drying and calcination, a catalyst for the production of homohydric anhydride from mesitylene is obtained. The catalyst prepared by the method of the present invention has the advantages of high conversion rate (maximum conversion rate 100%), high mass yield (maximum yield 128%), and high selectivity in the production of homohydric anhydride from mesitylene. It also has a high space velocity (up to 8000 h⁻¹). -1 It features short residence time, low catalyst dosage, and simple one-step reaction.

[0074] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A vanadium-titanium phosphorus-oxygen catalyst prepared with an ionic liquid auxiliary, characterized in that, The vanadium-titanium phosphorus-oxygen catalyst comprises a support and an active component and an ionic liquid supported on the support; The active component includes a vanadium source; the ionic liquid is a P-containing ionic liquid and / or a B-containing ionic liquid. The active component has a mass content of 0.01-40% of the vanadium-titanium-phosphorus-oxygen catalyst, and the ionic liquid has a mass content of 0.01-40% of the support.

2. The vanadium-titanium phosphorus-oxygen catalyst prepared by the ionic liquid auxiliary according to claim 1, characterized in that, The P-containing ionic liquid comprises one or more of [EMIM][PF6], [EMIM][DHP], [EMIM][DEP], [N1111][PF6], [Epy][PF6], [P4444]Cl, [P4444][PF6], [PMIM][DHP], and [EMIM][DMP]; the B-containing ionic liquid comprises one or more of [EMIM][BF4], [Epy][BF4], [N222][BF4], [EMPyrr][BF4], and [HOEMIM][BF4].

3. The vanadium-titanium phosphorus-oxygen catalyst prepared by the ionic liquid auxiliary according to claim 1 or 2, characterized in that, The vanadium source comprises vanadium pentoxide and / or ammonium metavanadate; The carrier is titanium dioxide, and the titanium dioxide has anatase and / or rutile crystal forms.

4. A method for preparing a vanadium-titanium phosphorus-oxygen catalyst using the ionic liquid auxiliaries according to any one of claims 1 to 3, characterized in that, Includes the following steps: 1) The active component is added to an oxalic acid solution to react and obtain the first impregnation solution; the ionic liquid is dissolved in water to obtain the second impregnation solution; 2) The carrier is sequentially immersed in the first impregnation solution and the second impregnation solution. After impregnation, excess water is removed, and then the carrier is dried and calcined in sequence to obtain the vanadium-titanium-phosphorus-oxygen catalyst.

5. The preparation method according to claim 4, characterized in that, In step 1), the reaction temperature is 70~90℃; the concentration of oxalic acid solution is 0.1~0.5g / mL; and the mass ratio of active component to oxalic acid is 1:1~3.

6. The preparation method according to claim 4 or 5, characterized in that, The drying temperature is 100~120℃, and the drying time is 10~20h.

7. The preparation method according to claim 6, characterized in that, The calcination temperature is 300~800℃, and the calcination time is 2~5h.

8. The application of the vanadium-titanium phosphorus-oxygen catalyst prepared by the ionic liquid auxiliaries according to any one of claims 1 to 3 in the catalytic production of homogeneous anhydride by mesitylene, characterized in that, The catalytic production of homogenate is carried out in a reactor, which can be a fixed-bed reactor, a moving-bed reactor, or a fluidized-bed reactor.

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