阅读说明：本技术 用于制备偏苯三酸酐的催化剂 (Catalyst for preparing trimellitic anhydride ) 是由 徐俊峰 顾龙勤 于 2018-06-05 设计创作，主要内容包括：本发明涉及一种用于制备偏苯三酸酐的催化剂,主要解决现有技术中用于制备偏苯三酸酐反应的催化剂性能较差,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、碱土金属元素,以及VA族元素和ⅢB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 preparing trimellitic anhydride, and mainly solves the problem that the performance of a catalyst for preparing trimellitic anhydride in the prior art is poor, so that the yield of the trimellitic anhydride is low. The invention adopts a supported catalyst, the active components of the catalyst comprise vanadium element, titanium element, alkaline earth metal element and at least one of VA group element and IIIB 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 preparing trimellitic anhydride is a supported catalyst taking vanadium and titanium as main catalytic elements, and the active components of the catalyst comprise vanadium, titanium, alkaline earth metal and at least one of VA 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 alkaline earth metal element is at least one element selected from the group consisting of Be, Mg, Ca, Sr and Ba.

3. The catalyst of claim 1, wherein the group VA element is selected from at least one of P, As, Sb and Bi.

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 alkaline earth 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 VA and group iiib elements in the catalyst is 1: (0.01-1).

7. A process for producing a catalyst for producing trimellitic anhydride using any one of the catalysts described in 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 alkaline earth metal elements, VA 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 according to claim 7, wherein the catalyst precursor is fed into a spray coater, heated at 125-335 ℃ 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 425 ℃ and 635 ℃ for a period of 1-14 hours.

10. a process for preparing trimellitic anhydride using the catalyst of any of claims 1 to 9, characterized in thatsynthesizing the meta-anhydride by using pseudocumene, water vapor and air as raw materials, and adopting a fixed bed reactor, wherein the feeding 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 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 preparing 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 has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for producing trimellitic anhydride, which is capable of solving the above-mentioned problems.

In order to solve one of the above technical problems, the technical solution disclosed by the present invention is: the catalyst for preparing trimellitic anhydride is a supported catalyst taking vanadium and titanium as main catalytic elements, and the active components of the catalyst comprise vanadium, titanium, alkaline earth metal and at least one of VA 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 alkaline earth metal, at least one element selected from group VA and at least one element selected from group iiib. 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 alkaline earth metal element is at least one selected from Be, Mg, Ca, Sr and Ba. More preferably Mg and Ca.

In the above technical solution, the VA group element is selected from at least one of P, As, Sb and Bi. More preferably P and Bi.

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 alkaline earth metal element, a VA group element, and a iiib group element; for example, the active components include V, Ti, Mg, P, and Sc, or V, Ti, Mg, P, Sc, and Y, or V, Ti, Mg, P, Bi, Sc, and Y.

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

The molar ratio of vanadium element to the sum of VA group element and IIIB group element in the catalyst is 1: (0.01-1), more preferably 1: (0.04-0.9).

To solve the second technical problem, the technical solution of the present invention is as follows: the process for producing a catalyst for trimellitic anhydride according to the technical solution to one of the above problems comprises 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 alkaline earth metal elements, VA 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 alkaline earth metal element in the step (1) is preferably at least one selected from the group consisting of an alkaline earth metal oxide, an alkaline earth metal chloride, an alkaline earth metal nitrate, an alkaline earth metal sulfate and an alkaline earth metal acetate. More preferred are magnesium nitrate and calcium nitrate. The compound of the VA group element in the step (1) is preferably at least one selected from ammonium dihydrogen phosphate, diammonium hydrogen phosphate, phosphoric acid, bismuth oxide, bismuth nitrate, bismuth chloride and bismuth sulfate. More preferred are phosphoric acid and bismuth nitrate. 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 chloride, and yttrium fluorite. More preferred are scandium chloride and yttrium chloride.

In the technical scheme, the preparation method of the catalyst for preparing the trimellitic anhydride 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 125-335 ℃.

In the technical scheme, the preparation method of the catalyst for preparing the trimellitic anhydride is characterized in that the carrier sprayed with the catalyst precursor is roasted in a muffle furnace, the roasting temperature is 425-635 ℃, and the roasting time is 1-14 h.

To solve the third technical problem, the technical scheme of the invention is as follows: the method for preparing trimellitic anhydride takes durene, water vapor and air as raw materials, adopts a fixed bed reactor, and synthesizes the trimellitic 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^-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, alkaline earth metal element and at least one element selected from VA 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 67.4 percent, better technical effect is achieved, and especially when the active component in the catalyst simultaneously comprises vanadium element, titanium element, alkaline earth metal element, at least one element selected from VA group elements and at least one element selected from IIIB group elements, more outstanding 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 ]

62g of oxalic acid and 198ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, 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. 2 mole fraction magnesium nitrate and 0.4 mole fraction phosphoric acid are added into the solution, and the reaction is continued for 1 hour at 60 ℃. Adding 31ml of distilled water into 7 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 65.6 percent, the evaluation result is detailed in table 1.

[ example 2 ]

62g of oxalic acid and 198ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, 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. 2 mol fraction of magnesium nitrate and 0.4 mol fraction of scandium chloride are added into the solution, and the reaction is continued for 1 hour at 60 ℃. Grinding 7 mol parts of titanium tetrachloride with 31ml of distilled water, adding the ground titanium tetrachloride into a reaction system, fully stirring the mixture to prepare slurry, and obtaining the titanium tetrachlorideAnd (4) driving the body. 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 65.5% by evaluation in a fixed bed reactor, the evaluation results are detailed in table 1.

Comparative example 1

62g of oxalic acid and 198ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, 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. 2 mol percent of magnesium nitrate is added into the solution, and the reaction is continued for 1 hour at 60 ℃. Adding 31ml of distilled water into 7 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 measured to be 62.6 percent by evaluation in a fixed bed reactor, 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 Mg active components and Sc active components by using the catalyst simultaneously containing V, Ti, Mg and P active components, and has higher yield of the partial anhydride.

[ example 3 ]

62g of oxalic acid and 198ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, 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. 2 mol fraction of calcium nitrate and 0.4 mol fraction of bismuth nitrate are added into the solution, and the reaction is continued for 1 hour at 60 ℃. Adding 31ml of distilled water into 7 molar parts of titanium dioxide, grinding, adding into a reaction system, and fully stirring to prepare slurry to obtain a precursor. Will be provided withThe 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 65.5% by evaluation in a fixed bed reactor, the evaluation results are detailed in table 1.

[ example 4 ]

62g of oxalic acid and 198ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, 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. 2 mole fraction magnesium nitrate and 0.4 mole fraction ammonium dihydrogen phosphate are added into the solution, and the reaction is continued for 1 hour at 60 ℃. Adding 31ml of distilled water into 7 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 65.4% by evaluation in a fixed bed reactor, the evaluation results are detailed in table 1.

[ example 5 ]

62g of oxalic acid and 198ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, 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. 2 mol fraction of calcium nitrate and 0.4 mol fraction of bismuth chloride are added into the solution, and the reaction is continued for 1 hour at 60 ℃. Adding 31ml of distilled water into 7 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 reactorThe molar yield of the metaanhydride was found to be 65.6%, and the evaluation results are shown in Table 1.

[ example 6 ]

62g of oxalic acid and 198ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, 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. 2 mol fraction of calcium nitrate and 0.4 mol fraction of yttrium chloride are added into the solution, and the reaction is continued for 1 hour at 60 ℃. Adding 31ml of distilled water into 7 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 65.5% by evaluation in a fixed bed reactor, the evaluation results are detailed in table 1.

[ example 7 ]

62g of oxalic acid and 198ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, 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. 2 mol fraction of calcium nitrate and 0.4 mol fraction of scandium sulfate are added into the solution, and the reaction is continued for 1 hour at 60 ℃. Adding 31ml of distilled water into 7 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 65.4% by evaluation in a fixed bed reactor, the evaluation results are detailed in table 1.

[ example 8 ]

62g of oxalic acid and 198ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, and after the oxalic acid is completely dissolved, an oxalic acid solution is prepared. 1 mole ofAdding the ammonium metavanadate in parts by mole into the prepared oxalic acid solution, and continuously stirring to obtain the ammonium vanadyl oxalate solution. 2 mol fraction of calcium nitrate and 0.4 mol fraction of yttrium fluorite are added into the solution, and the reaction is continued for 1 hour at the temperature of 60 ℃. Adding 31ml of distilled water into 7 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 65.3 percent, the evaluation result is detailed in table 1.

[ example 9 ]

62g of oxalic acid and 198ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, 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. 2 mol fraction of magnesium nitrate, 0.2 mol fraction of phosphoric acid and 0.2 mol fraction of scandium chloride are added into the solution, and the reaction is continued for 1 hour at 60 ℃. Adding 31ml of distilled water into 7 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.

compared with the examples 1-2, the VA group P element and the IIIB group Sc element have better synergistic effect on improving the yield of the partial anhydride.

[ example 10 ]

62g of oxalic acid and 198ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, 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 oxalic acidAmmonium vanadyl solution. Adding 2 mole fractions of magnesium nitrate, 0.1 mole fraction of phosphoric acid, 0.1 mole fraction of bismuth nitrate and 0.2 mole fraction of scandium chloride into the solution, and continuing the reaction at 60 ℃ for 1 hour. Adding 31ml of distilled water into 7 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 66.7% by evaluation in a fixed bed reactor, the evaluation results are detailed in table 1.

Compared with example 9, it can be seen that the elements of VA group P and Bi and other active components of the invention have better synergistic effect on increasing the yield of the partial anhydride.

[ example 11 ]

62g of oxalic acid and 198ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, 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. 2 mol fraction of calcium nitrate, 0.2 mol fraction of phosphoric acid, 0.1 mol fraction of scandium chloride and 0.1 mol fraction of yttrium chloride are added into the solution, and the reaction is continued for 1 hour at 60 ℃. Adding 31ml of distilled water into 7 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 66.8% 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 ]

Weighing 62g of grassacid and 198ml distilled water are put into a flask, stirred and heated to 85 ℃, and 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 2 mole parts of magnesium nitrate, 0.2 mole part of bismuth nitrate, 0.1 mole part of scandium chloride and 0.1 mole part of yttrium chloride into the solution, and continuing to react for 1 hour at 60 ℃. Adding 31ml of distilled water into 7 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 66.8% by evaluation in a fixed bed reactor, the evaluation results are detailed in table 1.

[ example 13 ]

62g of oxalic acid and 198ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, 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 2 mole parts of magnesium nitrate, 0.1 mole part of phosphoric acid, 0.1 mole part of bismuth nitrate, 0.1 mole part of scandium chloride and 0.1 mole part of yttrium chloride into the solution, and continuing to react for 1 hour at 60 ℃. Adding 31ml of distilled water into 7 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.

Compared with examples 10 and 11, V, Ti, alkaline earth Mg, VA group P and Bi elements, IIIB group Sc and Y elements have very good synergistic effect on improving the yield of the partial anhydride.

Comparative example 2

62g of oxalic acid and 198ml of distilled water are weighed in a flask, stirred and heated to 85 ℃, 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. 0.2 mole part of manganese nitrate and 0.2 mole part of cobalt nitrate are added into the solution, and the reaction is continued for 1 hour at 60 ℃. Adding 31ml of distilled water into 7 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 measured to be 62.9 percent when the evaluation is carried out in a fixed bed reactor, the evaluation result is detailed in the table 1.

TABLE 1