阅读说明：本技术 用于偏三甲苯氧化制备偏酐的催化剂 (Catalyst for oxidation of pseudocumene to prepare meta-anhydride ) 是由 顾龙勤 徐俊峰 陈亮 赵欣 于 2018-06-05 设计创作，主要内容包括：本发明涉及一种用于偏三甲苯氧化制备偏酐的催化剂,主要解决现有技术中偏三甲苯氧化制备偏酐时,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、碱金属元素,以及ⅢA族元素和ⅢB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。该方案减少了偏三甲苯氧化制备偏酐时副产物的生成,有效解决了偏酐收率低的问题。(The invention relates to a catalyst for preparing meta-anhydride by oxidizing meta-trimethylbenzene, which mainly solves the problem that the yield of the meta-anhydride is lower due to poor performance of the catalyst when the meta-trimethylbenzene is oxidized and prepared in the prior art. The invention adopts a supported catalyst, the active components of the catalyst comprise vanadium element, titanium element, alkali metal element and at least one of IIIA group element and IIIB group element, and the carrier is at least one of inert silicon carbide, alpha-alumina or ceramic ring. The scheme reduces the generation of byproducts in the preparation of the meta-anhydride by oxidizing the pseudocumene and effectively solves the problem of low yield of the meta-anhydride.)

1. The catalyst for preparing the meta-anhydride by oxidizing the pseudocumene 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 alkali metal elements and at least one of IIIA group elements and IIIB 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 alkali metal element is at least one element selected from the group consisting of Li, Na, K, Rb and Cs.

3. The catalyst of claim 1, wherein the group iiia element is selected from at least one of Al, Ga, In and Tl.

4. The catalyst of claim 1, wherein the group iiib element is selected from at least one of Sc and Y.

5. The catalyst of claim 1, wherein the molar ratio of vanadium, titanium and alkali elements 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 iiia and group iiib elements in the catalyst is 1: (0.01-1).

7. A method for preparing a catalyst for preparing a partial anhydride by oxidizing pseudocumene by using any one of the catalysts as claimed in claims 1 to 6, which 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 alkali metal elements, IIIA group elements and IIIB 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 as claimed in claim 7, wherein the precursor of the catalyst is loaded into a spraying machine, heated at 150-350 ℃ and then uniformly sprayed on the carrier.

9. the method as claimed in claim 7, wherein the carrier coated with the catalyst precursor is calcined in a muffle furnace at 450-650 ℃ for 2-12 h.

10. A method for preparing meta-anhydride by oxidizing pseudocumene, which adopts any one catalyst in claims 1-9, and is characterized in that the meta-anhydride is synthesized by taking pseudocumene, water vapor and air as raw materials, a fixed bed reactor is adopted, and the volume ratio of the pseudocumene to the water vapor 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 preparing meta-anhydride by oxidizing pseudocumene, a preparation method thereof and a synthesis method of the meta-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 meta-anhydride in the prior art, and the invention provides a catalyst for preparing the meta-anhydride by oxidizing the meta-trimethylbenzene, which has the characteristic of high yield of the meta-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 preparing a meta-anhydride, which is 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 synthesizing the meta-anhydride from the pseudocumene 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 alkali metal elements and at least one of IIIA group elements and IIIB group elements; the carrier of the catalyst is inert silicon carbide, alpha-alumina or ceramic ring.

Preferably, the active component includes vanadium, titanium, an alkali metal, at least one element selected from the group consisting of group iiia elements, and at least one element selected from the group consisting of group iiib elements at the same time. 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 alkali metal element is selected from at least one of Li, Na, K, Rb and Cs. More preferably, K and Rb are used.

In the above technical solution, the group iiia element is at least one selected from Al, Ga, In and Tl. More preferably Al and In.

In the above technical solution, the group iiib element is at least one selected from Sc and Y.

In the above technical solutions, as the most preferable technical solution, the active component simultaneously includes a vanadium element, a titanium element, an alkali metal element, a group iiia element, and a group iiib element; for example, the active components include V, Ti, K, Al and Sc, or V, Ti, K, Al, Sc and Y, or V, Ti, K, Al, In, Sc and Y.

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

the molar ratio of vanadium element to the sum of IIIA group element and IIIB group element in the catalyst is 1: (0.01-1), more preferably 1: (0.01-0.9).

To solve the second technical problem, the technical solution of the present invention is as follows: the preparation method of the catalyst for preparing the partial anhydride by oxidizing the pseudocumene 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 alkali metal elements, IIIA group elements and IIIB 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 compound of the alkali metal element in the step (1) is preferably at least one selected from salts such as potassium nitrate, potassium sulfate, potassium acetate, rubidium nitrate, rubidium sulfate and rubidium acetate. More preferably potassium nitrate and rubidium nitrate. The group IIIA element compound in the step (1) is preferably at least one selected from alumina, aluminum nitrate, aluminum sulfate, aluminum acetate, indium nitrate, indium sulfate, indium chloride and indium acetate. More preferably aluminum nitrate or indium acetate. The compound of the group IIIB element in step (1) is preferably at least one selected from the group consisting of scandium oxide, scandium halide, scandium sulfate, yttrium oxide, yttrium halide, fluorite. More preferred are scandium chloride and yttrium chloride.

In the technical scheme, the preparation method of the catalyst for preparing the meta-anhydride by oxidizing the pseudocumene is characterized in that a precursor of the catalyst is put into a spraying machine and is uniformly sprayed on a carrier after being heated at the temperature of 150-350 ℃.

In the technical scheme, the preparation method of the catalyst for preparing the meta-anhydride by oxidizing the pseudocumene is characterized in that the carrier sprayed with the catalyst precursor is roasted in a muffle furnace, the roasting temperature is 450-650 ℃, and the roasting time is 2-12 h.

To solve the third technical problem, the technical scheme of the invention is as follows: the preparation method of the meta-anhydride takes durene, water vapor and air as raw materials and adopts a fixed bed reactor to synthesize the meta-anhydride in the presence of a 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^-1Reaction temperatureThe 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, alkali metal element and at least one element selected from IIIA group element and IIIB group element, which is beneficial to improving the performance of the catalyst, thereby improving the yield of the metaanhydride.

The experimental result shows that the mole yield of the meta-anhydride prepared by the invention reaches 66.8%, and a better technical effect is achieved, particularly when the active component in the catalyst simultaneously comprises vanadium element, titanium element, alkali metal element, at least one element selected from IIIA group elements and at least one element selected from IIIB group elements, a more prominent technical effect is achieved, and the catalyst can be used for synthesis of the meta-anhydride. The invention is further illustrated by the following examples.

Detailed Description

[ example 1 ]

53g of oxalic acid and 187ml of distilled water are weighed into a flask, stirred and heated to 84 ℃, and after the oxalic acid is completely dissolved, an oxalic acid solution is prepared. And adding 1 mol part of ammonium metavanadate into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. The reaction was continued for 1h at 60 ℃ by adding 3 mole fraction potassium nitrate and 0.6 mole fraction aluminum nitrate to the solution. Adding 27ml of distilled water into 5 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 560 ℃ 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 65.1 percent, the evaluation result is detailed in table 1.

[ example 2 ]

53g of oxalic acid and 187ml of distilled water are weighed into a flask, stirred and heated to 84 ℃, and after the oxalic acid is completely dissolved, an oxalic acid solution is prepared. 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 mixing 3 moles ofThe molar fraction of potassium nitrate and 0.6 molar fraction of scandium chloride were added to the solution and the reaction was continued at 60 ℃ for 1 h. Adding 27ml of distilled water into 5 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 560 ℃ 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 measured to be 64.9 percent by evaluation in a fixed bed reactor, the evaluation result is detailed in table 1.

Comparative example 1

53g of oxalic acid and 187ml of distilled water are weighed into a flask, stirred and heated to 84 ℃, and after the oxalic acid is completely dissolved, an oxalic acid solution is prepared. And adding 1 mol part of ammonium metavanadate into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. The reaction was continued for 1h at 60 ℃ by adding 3 mole fraction potassium nitrate to the solution. Adding 27ml of distilled water into 5 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 560 ℃ 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 a catalyst containing only V, Ti and K active components and higher yield of the partial anhydride, and contains V, Ti, K and Al active components and V, Ti, K and Sc active components.

[ example 3 ]

53g of oxalic acid and 187ml of distilled water are weighed into a flask, stirred and heated to 84 ℃, and after the oxalic acid is completely dissolved, an oxalic acid solution is prepared. Adding 1 mol part of vanadium pentoxide into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. By mixing 3 mole fractions of nitreadding rubidium acid and 0.6 mol part of indium nitrate into the solution, and continuing to react for 1h at 60 ℃. Adding 5 molar parts of titanium tetrachloride into 27ml of distilled water, 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 560 ℃ 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 yield is 64.8 percent, and the evaluation result is detailed in table 1.

[ example 4 ]

53g of oxalic acid and 187ml of distilled water are weighed into a flask, stirred and heated to 84 ℃, and after the oxalic acid is completely dissolved, an oxalic acid solution is prepared. Adding 1 mol part of vanadium pentoxide into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. Adding 3 mole fractions of rubidium nitrate and 0.6 mole fraction of aluminum acetate into the solution, and continuing the reaction for 1 hour at 60 ℃. Adding 27ml of distilled water into 5 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 560 ℃ 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 65.1 percent, the evaluation result is detailed in table 1.

[ example 5 ]

53g of oxalic acid and 187ml of distilled water are weighed into a flask, stirred and heated to 84 ℃, and after the oxalic acid is completely dissolved, an oxalic acid solution is prepared. And adding 1 mol part of ammonium metavanadate into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. Adding 3 mole fraction potassium acetate and 0.6 mole fraction indium sulfate into the solution, and continuing the reaction at 60 ℃ for 1 h. Adding 5 molar parts of titanium tetrachloride into 27ml of distilled water, grinding, adding into a reaction system, and fully stirring to prepare slurry to obtain a precursor. Loading the catalyst precursor into a spraying machine, uniformly spraying the catalyst precursor on an inert carrier, and carbonizingOn silicon. Roasting at 560 ℃ 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 65.0% by evaluation in a fixed bed reactor, the evaluation results are shown in table 1.

[ example 6 ]

53g of oxalic acid and 187ml of distilled water are weighed into a flask, stirred and heated to 84 ℃, and after the oxalic acid is completely dissolved, an oxalic acid solution is prepared. Adding 1 mol part of vanadium pentoxide into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. Adding 3 mole fractions of rubidium nitrate and 0.6 mole fraction of yttrium chloride into the solution, and continuing the reaction for 1 hour at 60 ℃. Adding 5 molar parts of titanium tetrachloride into 27ml of distilled water, 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 560 ℃ 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 measured to be 64.9 percent by evaluation in a fixed bed reactor, the evaluation result is detailed in table 1.

[ example 7 ]

53g of oxalic acid and 187ml of distilled water are weighed into a flask, stirred and heated to 84 ℃, and after the oxalic acid is completely dissolved, an oxalic acid solution is prepared. Adding 1 mol part of vanadium pentoxide into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. 3 mole fractions of rubidium acetate and 0.6 mole fraction of scandium sulfate are added into the solution, and the reaction is continued for 1 hour at 60 ℃. Adding 27ml of distilled water into 5 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 560 ℃ 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 yield is 64.8 percent, and the evaluation result is detailed in table 1.

[ example 8 ]

53g of oxalic acid and 187ml of distilled water are weighed into a flask, stirred and heated to 84 ℃, and after the oxalic acid is completely dissolved, an oxalic acid solution is prepared. And adding 1 mol part of ammonium metavanadate into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. Adding 3 mole fraction potassium acetate and 0.6 mole fraction yttrium fluorite into the solution, and continuing the reaction for 1h at 60 ℃. Adding 5 molar parts of titanium tetrachloride into 27ml of distilled water, 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 560 ℃ 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 65.0% by evaluation in a fixed bed reactor, the evaluation results are shown in table 1.

[ example 9 ]

53g of oxalic acid and 187ml of distilled water are weighed into a flask, stirred and heated to 84 ℃, and after the oxalic acid is completely dissolved, an oxalic acid solution is prepared. And adding 1 mol part of ammonium metavanadate into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. 3 mole fractions of potassium nitrate, 0.3 mole fraction of aluminum nitrate and 0.3 mole fraction of scandium chloride were added to the solution, and the reaction was continued at 60 ℃ for 1 hour. Adding 27ml of distilled water into 5 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 560 ℃ 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 65.5% by evaluation in a fixed bed reactor, the evaluation results are detailed in table 1.

In this example, it can be seen that, compared with examples 1 to 2, the IIIA group Al element and the IIIB group Sc element have a better synergistic effect in increasing the yield of the partial anhydride.

[ example 10 ]

Weighing53g of oxalic acid and 187ml of distilled water are put into a flask, stirred and heated to 84 ℃, and after the oxalic acid is completely dissolved, an oxalic acid solution is prepared. And adding 1 mol part of ammonium metavanadate into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. The reaction was continued for 1 hour at 60 ℃ by adding 3 mole parts of potassium nitrate, 0.15 mole parts of aluminum nitrate, 0.15 mole parts of indium nitrate and 0.3 mole parts of scandium chloride to the solution. Adding 27ml of distilled water into 5 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 560 ℃ 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 66.2% by evaluation in a fixed bed reactor, the evaluation results are detailed in table 1.

In this example, it can be seen that group IIIA Al and In have a better synergistic effect with the other active components of the present invention In increasing the yield of the partial anhydride than example 9.

[ example 11 ]

53g of oxalic acid and 187ml of distilled water are weighed into a flask, stirred and heated to 84 ℃, and after the oxalic acid is completely dissolved, an oxalic acid solution is prepared. And adding 1 mol part of ammonium metavanadate into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. 3 mole parts of potassium nitrate, 0.3 mole part of aluminum nitrate, 0.15 mole part of scandium chloride and 0.15 mole part of scandium yttrium chloride are added into the solution, and the reaction is continued for 1 hour at 60 ℃. Adding 27ml of distilled water into 5 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 560 ℃ 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.

In this example, it can be seen from comparison with example 9 that the elements Sc and Y of group IIIB have a better synergistic effect with other active ingredients of the present invention in increasing the yield of the partial anhydride.

[ example 12 ]

53g of oxalic acid and 187ml of distilled water are weighed into a flask, stirred and heated to 84 ℃, and after the oxalic acid is completely dissolved, an oxalic acid solution is prepared. And adding 1 mol part of ammonium metavanadate into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. The reaction is continued for 1h at 60 ℃ by adding 3 mole fractions of potassium nitrate, 0.3 mole fraction of indium nitrate, 0.15 mole fraction of scandium chloride and 0.15 mole fraction of scandium yttrium chloride into the solution. Adding 27ml of distilled water into 5 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 560 ℃ 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 13 ]

53g of oxalic acid and 187ml of distilled water are weighed into a flask, stirred and heated to 84 ℃, and after the oxalic acid is completely dissolved, an oxalic acid solution is prepared. And adding 1 mol part of ammonium metavanadate into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. The reaction was continued for 1 hour at 60 ℃ by adding 3 mole parts of potassium nitrate, 0.15 mole parts of aluminum nitrate, 0.15 mole parts of indium nitrate, 0.15 mole parts of scandium chloride and 0.15 mole parts of scandium yttrium chloride to the solution. Adding 27ml of distilled water into 5 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 560 ℃ 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 66.8% by evaluation in a fixed bed reactor, the evaluation results are detailed in table 1.

Compared with examples 10 and 11, V, Ti, alkali metals K, IIIA group Al and In elements and IIIB group Sc and Y elements have very good synergistic effect on improving the yield of the partial anhydride.

Comparative example 2

53g of oxalic acid and 187ml of distilled water are weighed into a flask, stirred and heated to 84 ℃, and after the oxalic acid is completely dissolved, an oxalic acid solution is prepared. And adding 1 mol part of ammonium metavanadate into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. 0.3 mole part of manganese nitrate and 0.3 mole part of cobalt nitrate are added into the solution, and the reaction is continued for 1 hour at 60 ℃. Adding 27ml of distilled water into 5 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 560 ℃ 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 meta-anhydride is 63.1% by evaluation in a fixed bed reactor, the evaluation results are shown in table 1.

TABLE 1