阅读说明：本技术 用于提高偏苯三酸酐收率的催化剂 (Catalyst for improving yield of trimellitic anhydride ) 是由 徐俊峰 顾龙勤 王丹柳 周继鹏 方敏 于 2018-06-05 设计创作，主要内容包括：本发明涉及一种用于提高偏苯三酸酐收率的催化剂,主要解决现有技术中用于制备偏苯三酸酐的催化剂性能较差,导致偏酐收率较低的问题。本发明采用负载型催化剂,所述催化剂的活性组分包括钒元素、钛元素、铁系金属元素,以及IVA族元素和VIB族元素中的至少一种,载体为惰性的碳化硅、α-氧化铝或瓷环的至少一种的技术方案。该方案提高了制备偏苯三酸酐催化剂的性能,有效提高了偏酐收率。(The invention relates to a catalyst for improving the yield of trimellitic anhydride, and mainly solves the problem that the performance of the catalyst for preparing trimellitic anhydride is poor in the prior art, so that the yield of trimellitic anhydride is low. The invention adopts a supported catalyst, the active components of the catalyst comprise vanadium element, titanium element, iron series metal element and at least one of IVA group element and VIB group element, and the carrier is at least one of inert silicon carbide, alpha-alumina or ceramic ring. The scheme improves the performance of the catalyst for preparing the trimellitic anhydride and effectively improves the yield of the trimellitic anhydride.)

1. The catalyst for improving the yield of trimellitic anhydride is characterized in that the catalyst is a supported catalyst taking vanadium and titanium as main catalytic elements, and the active components of the catalyst comprise vanadium, titanium and iron metal elements and at least one of IVA group elements and VIB group elements; the carrier of the catalyst is inert silicon carbide, alpha-alumina or ceramic ring.

2. The catalyst according to claim 1, wherein the iron-based element is at least one selected from the group consisting of Fe, Co and Ni.

3. The catalyst of claim 1, wherein the group IVA element is selected from the group consisting of Ge, Sn and Pb.

4. The catalyst of claim 1, wherein the group VIB element is at least one element selected from the group consisting of Cr, Mo, and W.

5. The catalyst according to claim 1, wherein the molar ratio of the vanadium element, the titanium element and the iron-based metal element in the catalyst is 1: (1-15): (0.1-5).

6. The catalyst of claim 1, wherein the molar ratio of vanadium to the sum of group IVA and group VIB elements in the catalyst is 1: (0.01-1).

7. A method for preparing a catalyst for increasing the yield of trimellitic anhydride by using the catalyst according to any one of claims 1 to 6, comprising the steps of:

(1) dissolving oxalic acid in distilled water to obtain an oxalic acid solution; adding a vanadium source into an oxalic acid solution to obtain a mixed solution; adding iron series metal elements, IVA group elements and VIB group element compounds into a reaction system;

(2) Adding water into a titanium source, grinding, slowly dropwise adding the ground titanium source into a reaction system, and fully stirring to prepare slurry to obtain a precursor;

(3) Spraying the precursor onto a carrier, wherein the molar ratio of the precursor to the carrier is 1 (1-10), and roasting to obtain the catalyst.

8. The method according to claim 7, wherein the catalyst precursor is fed into a spray coater, heated at 133-344 ℃ and uniformly sprayed on the carrier.

9. The method according to claim 7, wherein the carrier coated with the catalyst precursor is calcined in a muffle furnace at a temperature of 422 ℃ and 633 ℃ for 1-12 h.

10. a method for improving yield of trimellitic anhydride by using any one of the catalysts in claims 1-9, and is characterized in that trimellitic anhydride is synthesized by using trimellitic benzene, steam and air as raw materials and adopting a fixed bed reactor, wherein the feeding volume ratio of the trimellitic benzene to the steam is 1: 1-30, and the reaction process conditions are as follows: the space velocity is 1000-10000 hr^-1The reaction temperature is 300-600 ℃, and the reaction pressure is normal pressure.

Technical Field

The invention relates to a catalyst for improving yield of trimellitic anhydride, a preparation method thereof and a synthesis method of the trimellitic anhydride.

Technical Field

Trimellitic anhydride (TMA), also known as 1, 2, 4-benzene tricarboxylic anhydride for short, is an important chemical raw material and a high value-added intermediate, and is widely applied to the production industries of high-temperature-resistant plasticizers, polyester resins, polyester epoxy powder coatings, insulating paint, water-soluble alkyd resins, lubricating oil, printing ink, adhesives and the like. The prepared resin material has excellent point insulation performance, high temperature resistance and mechanical performance, and is widely applied to the industrial fields of electronics, aerospace, electromechanics and the like.

At present, the production of the meta-anhydride in the world is mainly based on the pseudocumene liquid-phase oxidation technology represented by the United states and Japan, and accounts for about 70 percent of the total production in the world. The process takes pseudocumene as a raw material, takes Co-Mn-Br as a catalyst in an acetic acid medium, and prepares the meta-anhydride by air oxidation. The process has high yield of the meta-anhydride, but has long reaction flow, serious corrosion to equipment and large investment, and can bring pressure to the production cost. The gas phase oxidation method is a method for directly generating the meta-anhydride by using the air to carry out one-step oxidation by using the pseudocumene as a raw material under the action of a catalyst. Compared with the liquid phase oxidation method, the method avoids the problems, has low production cost and is the most ideal method for producing the meta-anhydride.

At present, the gas phase oxidation method causes high international attention, and research work of the method is developed in many times. German GE 1518613 researches V-Mo-Cu catalyst for gas phase oxidation reaction of unsym-trimethyl benzene, and obtains good catalytic effect. CN105498817A researches a V-Ti-Mn-Co metal oxide and heteropoly acid composite catalyst, and the molar yield can reach 56.2%. Compared with the prior art at home and abroad, the prior art at home is still imperfect, has low construction rate and can not meet the market demand of the domestic meta-anhydride. Therefore, it is necessary to improve the selectivity of the catalyst to the partial anhydride by changing the preparation method of the catalyst.

Disclosure of Invention

One of the technical problems to be solved by the invention is the problem of low yield of the trimellitic anhydride in the prior art, and the catalyst for improving the yield of the trimellitic anhydride has the characteristic of high yield of the trimellitic anhydride.

The second technical problem to be solved by the present invention is to provide a method for preparing a catalyst corresponding to the first technical problem.

The present invention is also directed to a method for increasing the yield of trimellitic anhydride, which corresponds to one of the technical problems to be solved.

In order to solve one of the above technical problems, the technical solution disclosed by the present invention is: the catalyst for improving the yield of trimellitic anhydride is characterized in that the catalyst is a supported catalyst taking vanadium and titanium as main catalytic elements, and the active components of the catalyst comprise vanadium, titanium and iron metal elements and at least one of IVA group elements and VIB group elements; the carrier of the catalyst is inert silicon carbide, alpha-alumina or ceramic ring.

Preferably, the active component comprises vanadium, titanium, iron-based metal, at least one element selected from group IVA elements, and at least one element selected from group VIB elements. At the moment, the five elements have synergistic effect on the aspect of improving the yield of the partial anhydride.

In the above technical solution, the iron-based element is selected from at least one of Fe, Co and Ni. More preferably Fe and Ni.

In the above technical solution, the group IVA element is selected from at least one of Ge, Sn, and Pb. Ge and Sn are more preferred.

In the above technical solution, the group VIB element is at least one selected from Cr, Mo, and W. More preferably Cr and Mo.

in the above technical solution, as the most preferable technical solution, the active component simultaneously includes a vanadium element, a titanium element, an iron-based metal element, an IVA group element, and a VIB group element; for example, the active component includes V, Ti, Fe, Ge and Cr, or V, Ti, Fe, Ge, Cr and Mo, or V, Ti, Fe, Ge, Sn, Cr and Mo.

In the technical scheme, the molar ratio of the vanadium element, the titanium element and the iron-based metal element in the catalyst is 1: (1-15): (0.1-5);

The molar ratio of the vanadium element to the sum of the elements of the IVA group and the VIB group in the catalyst is 1: (0.01-1), more preferably 1: (0.25-0.85).

To solve the second technical problem, the technical solution of the present invention is as follows: the preparation method of the catalyst for increasing the yield of trimellitic anhydride described in the technical scheme of one of the above technical problems comprises the following steps:

(1) Dissolving oxalic acid in distilled water to obtain an oxalic acid solution; adding a vanadium source into an oxalic acid solution to obtain a mixed solution; adding iron series metal elements, IVA group elements and VIB group element compounds into a reaction system;

(2) Adding water into a titanium source, grinding, slowly dropwise adding the ground titanium source into a reaction system, and fully stirring to prepare slurry to obtain a precursor;

(3) Spraying the precursor onto a carrier, wherein the molar ratio of the precursor to the carrier is 1 (1-10), and roasting to obtain the catalyst.

in the above technical solution, the vanadium source in step (1) is preferably at least one selected from vanadium oxide, metavanadate, orthovanadate and vanadium chloride. The titanium source in the step (2) is preferably at least one of titanium dioxide and titanium tetrachloride. The iron-based element in step (1) is preferably at least one of metal salts such as iron oxide, iron chloride, iron nitrate, iron sulfate, iron acetate, cobalt oxide, cobalt nitrate, cobalt sulfate, cobalt acetate, nickel oxide, nickel nitrate, nickel sulfate, and nickel acetate. More preferred are iron nitrate and nickel nitrate. The compound of the group IVA element in the step (1) is preferably at least one selected from the group consisting of germanium oxide, germanium halide, organogermanide, tin oxide, tin sulfide, tin halide, inorganic salts of tin, lead oxide, lead sulfide, lead sulfate, lead nitrate and lead acetate. Tin chloride and germanium chloride are more preferred. The group VIB element compound in step (1) is preferably at least one selected from chromium oxide, chromium chloride, chromium salt, chromate, molybdenum oxide, molybdenum chloride, molybdenum salt and molybdate. More preferred are chromium chloride and ammonium molybdate.

In the technical scheme, the preparation method of the catalyst for improving the yield of the trimellitic anhydride is characterized in that a precursor of the catalyst is loaded into a spraying machine, and the precursor is uniformly sprayed on a carrier after being heated at the temperature of 133-344 ℃.

In the technical scheme, the preparation method of the catalyst for improving the yield of the trimellitic anhydride is characterized in that the carrier sprayed with the catalyst precursor is roasted in a muffle furnace, the roasting temperature is 422-633 ℃, and the roasting time is 1-12 h.

To solve the third technical problem, the technical scheme of the invention is as follows: the method for raising yield of trimellitic anhydride uses durene, water vapour and air as raw material, and adopts fixed bed reactor to synthesize trimellitic anhydride in the presence of catalyst.

The reaction process conditions in the technical scheme are as follows: the volume ratio of the pseudocumene to the steam is 1: 1-30, and the reaction process conditions are as follows: the space velocity is 1000-10000 hr^-1the reaction temperature is 300-600 ℃, and the reaction pressure is normal pressure.

Compared with the prior art, the key point of the invention is that the active component of the catalyst comprises a certain amount of vanadium element, titanium element, iron series metal element and at least one element selected from IVA group element and VIB group element, which is beneficial to improving the performance of the catalyst, thereby improving the yield of the meta-anhydride.

The experimental result shows that the mole yield of the meta-anhydride prepared by the invention reaches 68.1%, and a better technical effect is achieved, particularly when the active component in the catalyst simultaneously comprises vanadium element, titanium element, iron metal element, at least one element selected from IVA group elements and at least one element selected from VIB group elements, a more prominent technical effect is achieved, and the catalyst can be used for synthesizing the meta-anhydride. The invention is further illustrated by the following examples.

Detailed Description

[ example 1 ]

55g of oxalic acid and 175ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, and the oxalic acid solution is prepared after the oxalic acid is completely dissolved. Adding 1 mol part of vanadium pentoxide into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. 4 mole fraction nickel nitrate and 0.8 mole fraction stannic chloride are added into the solution, and the reaction is continued for 1 hour at 60 ℃. Adding 31ml of distilled water into 6 molar parts of titanium tetrachloride, grinding, adding into a reaction system, and fully stirring to prepare slurry to obtain a precursor. The catalyst precursor is loaded into a spraying machine and evenly sprayed on the inert carrier silicon carbide. Roasting at 575 deg.c in a muffle furnace, and naturally cooling to obtain the catalyst. The catalyst is reacted at the temperature of 400 ℃ and the space velocity of 3000 hours^-1The following, pseudocumene: when the steam is 0.05 and the mole yield of the partial anhydride is determined to be 66.1% by evaluation in a fixed bed reactor, the evaluation results are detailed in table 1.

[ example 2 ]

55g of oxalic acid and 175ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, and the oxalic acid solution is prepared after the oxalic acid is completely dissolved. Adding 1 mol part of vanadium pentoxide into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. Adding 4 mole fraction nickel nitrate and 0.8 mole fraction ammonium molybdate into the solution, and continuing the reaction for 1h at 60 ℃. Adding 31ml of distilled water into 6 molar parts of titanium tetrachloride, grinding, adding into a reaction system, and fully stirring to prepare slurry to obtain a precursor. The catalyst precursor is loaded into a spraying machine and evenly sprayed on the inert carrier silicon carbide. Roasting at 575 deg.c in a muffle furnace, and naturally cooling to obtain the catalyst. The catalyst is reacted at the temperature of 400 ℃ and the space velocity of 3000 hours^-1The following, pseudocumene: when the steam is 0.05 and the mole yield of the partial anhydride is determined to be 66.0% by evaluation in a fixed bed reactor, the evaluation results are detailed in table 1.

Comparative example 1

55g of oxalic acid and 175ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, and the oxalic acid solution is prepared after the oxalic acid is completely dissolved. Adding 1 mol part of vanadium pentoxide into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. Adding 4 mole fraction nickel nitrate into the solution, and continuing the reaction for 1h at 60 ℃. Adding 31ml of distilled water into 6 molar parts of titanium tetrachloride, grinding, adding into a reaction system, and fully stirring to prepare slurry to obtain a precursor. The catalyst precursor is loaded into a spraying machine and evenly sprayed on the inert carrier silicon carbide. Roasting at 575 deg.c in a muffle furnace, and naturally cooling to obtain the catalyst. The catalyst is reacted at the temperature of 400 ℃ and the space velocity of 3000 hours^-1The following, pseudocumene: when the steam is 0.05 and the mole yield of the partial anhydride is measured in a fixed bed reactor, the mole yield of the partial anhydride is 62.1 percent, and the evaluation result is detailed in table 1.

Compared with the examples 1-2, the catalyst adopted by the invention has better performance than that of a catalyst only containing V, Ti and Ni active components and containing V, Ti, Ni and Mo active components, and has higher yield of the meta-anhydride.

[ example 3 ]

55g of oxalic acid and 175ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, and the oxalic acid solution is prepared after the oxalic acid is completely dissolved. And adding 1 mol part of ammonium metavanadate into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. 4 mol fraction ferric nitrate and 0.8 mol fraction germanium chloride are added into the solution, and the reaction is continued for 1 hour at 60 ℃. Adding 31ml of distilled water into 6 molar parts of titanium dioxide, grinding, adding into a reaction system, and fully stirring to prepare slurry to obtain a precursor. The catalyst precursor is loaded into a spraying machine and evenly sprayed on the inert carrier silicon carbide. Roasting at 575 deg.c in a muffle furnace, and naturally cooling to obtain the catalyst. The catalyst is reacted at the temperature of 400 ℃ and the space velocity of 3000 hours^-1The following, pseudocumene: when the steam is 0.05 and the mole yield of the metaanhydride is 65.8 percent, the evaluation result is detailed in table 1.

[ example 4 ]

55g of oxalic acid and 175ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, and the oxalic acid solution is prepared after the oxalic acid is completely dissolved. Adding 1 mol part of vanadium pentoxide into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. 4 mol fraction ferric nitrate and 0.8 mol fraction stannic sulfide are added into the solution, and the reaction is continued for 1 hour at 60 ℃. Adding 31ml of distilled water into 6 molar parts of titanium dioxide, grinding, adding into a reaction system, and fully stirring to prepare slurry to obtain a precursor. The catalyst precursor is loaded into a spraying machine and evenly sprayed on the inert carrier silicon carbide. Roasting at 575 deg.c in a muffle furnace, and naturally cooling to obtain the catalyst. The catalyst is reacted at the temperature of 400 ℃ and the space velocity of 3000 hours^-1The following, pseudocumene: when the steam is 0.05 and the mole yield of the metaanhydride is 65.9 percent, the evaluation result is detailed in table 1.

[ example 5 ]

55g of oxalic acid and 175ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, and the oxalic acid solution is prepared after the oxalic acid is completely dissolved. And adding 1 mol part of ammonium metavanadate into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. By usingAdding nickel nitrate with the mole fraction of 4 and germanium sulfide with the mole fraction of 0.8 into the solution, and continuing to react for 1 hour at the temperature of 60 ℃. Adding 31ml of distilled water into 6 molar parts of titanium tetrachloride, grinding, adding into a reaction system, and fully stirring to prepare slurry to obtain a precursor. The catalyst precursor is loaded into a spraying machine and evenly sprayed on the inert carrier silicon carbide. Roasting at 575 deg.c in a muffle furnace, and naturally cooling to obtain the catalyst. The catalyst is reacted at the temperature of 400 ℃ and the space velocity of 3000 hours^-1The following, pseudocumene: when the steam is 0.05 and the mole yield of the partial anhydride is determined to be 66.0% by evaluation in a fixed bed reactor, the evaluation results are detailed in table 1.

[ example 6 ]

55g of oxalic acid and 175ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, and the oxalic acid solution is prepared after the oxalic acid is completely dissolved. And adding 1 mol part of ammonium metavanadate into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. 4 mole fraction nickel nitrate and 0.8 mole fraction molybdic acid are added into the solution, and the reaction is continued for 1h at 60 ℃. Adding 31ml of distilled water into 6 molar parts of titanium dioxide, grinding, adding into a reaction system, and fully stirring to prepare slurry to obtain a precursor. The catalyst precursor is loaded into a spraying machine and evenly sprayed on the inert carrier silicon carbide. Roasting at 575 deg.c in a muffle furnace, and naturally cooling to obtain the catalyst. The catalyst is reacted at the temperature of 400 ℃ and the space velocity of 3000 hours^-1The following, pseudocumene: when the steam is 0.05 and the mole yield of the partial anhydride is determined to be 66.1% by evaluation in a fixed bed reactor, the evaluation results are detailed in table 1.

[ example 7 ]

55g of oxalic acid and 175ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, and the oxalic acid solution is prepared after the oxalic acid is completely dissolved. Adding 1 mol part of vanadium pentoxide into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. 4 mol fraction ferric nitrate and 0.8 mol fraction chromium chloride are added into the solution, and the reaction is continued for 1 hour at 60 ℃. Adding 31ml of distilled water into 6 molar parts of titanium dioxide, grinding, adding into a reaction system, and fully stirring to prepare slurry to obtain a precursor. Loading the catalyst precursor into a spraying machine, and uniformly spraying the catalyst precursor on the inert materialon a carrier of silicon carbide. Roasting at 575 deg.c in a muffle furnace, and naturally cooling to obtain the catalyst. The catalyst is reacted at the temperature of 400 ℃ and the space velocity of 3000 hours^-1The following, pseudocumene: when the steam is 0.05 and the mole yield of the metaanhydride is 65.9 percent, the evaluation result is detailed in table 1.

[ example 8 ]

55g of oxalic acid and 175ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, and the oxalic acid solution is prepared after the oxalic acid is completely dissolved. And adding 1 mol part of ammonium metavanadate into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. 4 mol fraction ferric nitrate and 0.8 mol fraction chromium sulfate are added into the solution, and the reaction is continued for 1 hour at 60 ℃. Adding 31ml of distilled water into 6 molar parts of titanium tetrachloride, grinding, adding into a reaction system, and fully stirring to prepare slurry to obtain a precursor. The catalyst precursor is loaded into a spraying machine and evenly sprayed on the inert carrier silicon carbide. Roasting at 575 deg.c in a muffle furnace, and naturally cooling to obtain the catalyst. The catalyst is reacted at the temperature of 400 ℃ and the space velocity of 3000 hours^-1The following, pseudocumene: when the steam is 0.05 and the mole yield of the metaanhydride is 65.8 percent, the evaluation result is detailed in table 1.

[ example 9 ]

55g of oxalic acid and 175ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, and the oxalic acid solution is prepared after the oxalic acid is completely dissolved. Adding 1 mol part of vanadium pentoxide into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. Adding 4 mole fraction nickel nitrate, 0.4 mole fraction stannic chloride and 0.4 mole fraction ammonium molybdate into the solution, and continuing the reaction for 1h at 60 ℃. Adding 31ml of distilled water into 6 molar parts of titanium tetrachloride, grinding, adding into a reaction system, and fully stirring to prepare slurry to obtain a precursor. The catalyst precursor is loaded into a spraying machine and evenly sprayed on the inert carrier silicon carbide. Roasting at 575 deg.c in a muffle furnace, and naturally cooling to obtain the catalyst. The catalyst is reacted at the temperature of 400 ℃ and the space velocity of 3000 hours^-1The following, pseudocumene: steam 0.05, evaluated in a fixed bed reactor, gave a molar yield of 66.7% of meta-anhydride, which isThe evaluation results are detailed in table 1.

Compared with the examples 1-2, the example shows that the elements of the IVA group Sn and the VIB group Mo have better synergistic effect on improving the yield of the partial anhydride.

[ example 10 ]

55g of oxalic acid and 175ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, and the oxalic acid solution is prepared after the oxalic acid is completely dissolved. Adding 1 mol part of vanadium pentoxide into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. Adding 4 mole fraction nickel nitrate, 0.2 mole fraction stannic chloride, 0.2 mole fraction germanium chloride and 0.4 mole fraction ammonium molybdate into the solution, and continuing to react for 1h at 60 ℃. Adding 31ml of distilled water into 6 molar parts of titanium tetrachloride, grinding, adding into a reaction system, and fully stirring to prepare slurry to obtain a precursor. The catalyst precursor is loaded into a spraying machine and evenly sprayed on the inert carrier silicon carbide. Roasting at 575 deg.c in a muffle furnace, and naturally cooling to obtain the catalyst. The catalyst is reacted at the temperature of 400 ℃ and the space velocity of 3000 hours^-1The following, pseudocumene: when the steam is 0.05 and the yield of the metaanhydride is 67.3% by mole, the steam is evaluated in a fixed bed reactor, and the evaluation results are detailed in table 1.

Compared with example 9, the example shows that the elements of group IVA Sn and Ge have better synergistic effect on improving the yield of the partial anhydride with other active components of the invention.

[ example 11 ]

55g of oxalic acid and 175ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, and the oxalic acid solution is prepared after the oxalic acid is completely dissolved. Adding 1 mol part of vanadium pentoxide into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. Adding 4 mole fraction nickel nitrate, 0.4 mole fraction stannic chloride, 0.2 mole fraction ammonium molybdate and 0.2 mole fraction chromium chloride into the solution, and continuing to react for 1h at 60 ℃. Adding 31ml of distilled water into 6 molar parts of titanium tetrachloride, grinding, adding into a reaction system, and fully stirring to prepare slurry to obtain a precursor. The catalyst precursor is loaded into a spraying machine and evenly sprayed on the inert carrier silicon carbide. Roasting at 575 deg.c in muffle furnace and naturally cooling to obtain catalystAn oxidizing agent. The catalyst is reacted at the temperature of 400 ℃ and the space velocity of 3000 hours^-1The following, pseudocumene: when the steam is 0.05 and the yield is 67.5%, the evaluation is shown in Table 1.

Compared with example 9, this example shows that the group VIB elements Mo and Cr and other active components of the present invention have a better synergistic effect in increasing the yield of the partial anhydride.

[ example 12 ]

55g of oxalic acid and 175ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, and the oxalic acid solution is prepared after the oxalic acid is completely dissolved. Adding 1 mol part of vanadium pentoxide into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. Adding 4 mole fractions of ferric nitrate, 0.4 mole fraction of germanium chloride, 0.2 mole fraction of ammonium molybdate and 0.2 mole fraction of chromium chloride into the solution, and continuing the reaction at 60 ℃ for 1 hour. Adding 31ml of distilled water into 6 molar parts of titanium tetrachloride, grinding, adding into a reaction system, and fully stirring to prepare slurry to obtain a precursor. The catalyst precursor is loaded into a spraying machine and evenly sprayed on the inert carrier silicon carbide. Roasting at 575 deg.c in a muffle furnace, and naturally cooling to obtain the catalyst. The catalyst is reacted at the temperature of 400 ℃ and the space velocity of 3000 hours^-1The following, pseudocumene: when the steam is 0.05 and the yield is 67.4%, the evaluation is shown in Table 1.

[ example 13 ]

55g of oxalic acid and 175ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, and the oxalic acid solution is prepared after the oxalic acid is completely dissolved. Adding 1 mol part of vanadium pentoxide into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. Adding 4 mole fractions of ferric nitrate, 0.2 mole fraction of stannic chloride, 0.2 mole fraction of germanium chloride, 0.2 mole fraction of ammonium molybdate and 0.2 mole fraction of chromium chloride into the solution, and continuing the reaction at 60 ℃ for 1 hour. Adding 31ml of distilled water into 6 molar parts of titanium tetrachloride, grinding, adding into a reaction system, and fully stirring to prepare slurry to obtain a precursor. The catalyst precursor is loaded into a spraying machine and evenly sprayed on the inert carrier silicon carbide. In thatRoasting in a muffle furnace at 575 ℃, and naturally cooling to obtain the catalyst. The catalyst is reacted at the temperature of 400 ℃ and the space velocity of 3000 hours^-1The following, pseudocumene: steam 0.05, and the molar yield of the meta-anhydride was 68.1% when evaluated in a fixed bed reactor, the evaluation results are detailed in table 1.

Compared with examples 10 and 11, V, Ti, Fe, IVA Sn and Ge, and VIB Mo and Cr have excellent synergistic effect in raising the yield of partial anhydride.

Comparative example 2

55g of oxalic acid and 175ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, and the oxalic acid solution is prepared after the oxalic acid is completely dissolved. Adding 1 mol part of vanadium pentoxide into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. 0.4 mol parts of manganese nitrate and 0.4 mol parts of cobalt nitrate are added into the solution, and the reaction is continued for 1 hour at 60 ℃. Adding 31ml of distilled water into 6 molar parts of titanium tetrachloride, grinding, adding into a reaction system, and fully stirring to prepare slurry to obtain a precursor. The catalyst precursor is loaded into a spraying machine and evenly sprayed on the inert carrier silicon carbide. Roasting at 575 deg.c in a muffle furnace, and naturally cooling to obtain the catalyst. The catalyst is reacted at the temperature of 400 ℃ and the space velocity of 3000 hours^-1The following, pseudocumene: when the steam is 0.05 and the mole yield of the partial anhydride is measured in a fixed bed reactor, the mole yield of the partial anhydride is 62.2 percent, and the evaluation result is detailed in table 1.

TABLE 1