阅读说明：本技术 用于偏三甲苯催化氧化的催化剂 (Catalyst for pseudocumene catalytic oxidation ) 是由 徐俊峰 顾龙勤 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偏三甲苯催化氧化的催化剂,主要解决现有技术中偏三甲苯催化氧化反应,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VIB族元素和非金属元素中的至少一种,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。该方案提高了偏三甲苯催化氧化催化剂的性能,有效提高了偏酐收率。(The invention relates to a catalyst for pseudocumene catalytic oxidation, which mainly solves the problem of low yield of the metanhydride caused by poor performance of the catalyst in the pseudocumene catalytic oxidation reaction 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 VIB group element and nonmetal element, and the carrier is at least one of inert silicon carbide, alpha-alumina or ceramic ring. The scheme improves the performance of the pseudocumene catalytic oxidation catalyst and effectively improves the yield of the metaanhydride.)

1. The catalyst for the catalytic oxidation of 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, alkali metal and at least one of VIB group elements and nonmetal 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 VIB element is at least one element selected from the group consisting of Cr, Mo, and W.

4. The catalyst according to claim 1, wherein said nonmetallic element is at least one selected from the group consisting of B, Si, As and Te.

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 the group VIB elements and the nonmetallic elements in the catalyst is 1: (0.01-1).

7. A method for preparing a catalyst for the catalytic oxidation of 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, VIB group elements and nonmetal 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, and is uniformly sprayed on the carrier after being heated at 140 ℃ and 330 ℃.

9. The method as claimed in claim 7, wherein the carrier coated with the catalyst precursor is calcined in a muffle furnace at a temperature of 420-630 ℃ for 2-13 h.

10. A method for the catalytic oxidation of pseudocumene, which adopts any one catalyst in claims 1 to 9, is characterized in that pseudocumene, water vapor and air are used as raw materials to synthesize the metaanhydride, 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 pseudocumene catalytic oxidation, a preparation method thereof and a synthesis method of 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 the catalytic oxidation of 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 invention aims to solve the technical problem and provides a method for catalyzing and oxidizing the meta-anhydride corresponding to one of the technical problems.

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, alkali metal and at least one of VIB group elements and nonmetal elements; the carrier of the catalyst is inert silicon carbide, alpha-alumina or ceramic ring

Preferably, the active component comprises vanadium, titanium, alkali metal, at least one element selected from group VIB elements and at least one element selected from non-metal 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 alkali metal element is selected from at least one of Li, Na, K, Rb and Cs. More preferably Na and Rb.

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, the nonmetal element is selected from at least one of B, Si, As and Te. More preferably B and Si.

In the above technical solution, as the most preferable technical solution, the active component simultaneously includes a vanadium element, a titanium element, an alkali metal element, a VIB group element, and a nonmetal element; for example, the active component includes V, Ti, Na, Cr and B, or V, Ti, Na, Cr, B and Si, or V, Ti, Na, Cr, Mo, B and Si.

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 VIB group element and nonmetal element in the catalyst is 1: (0.01-1), more preferably 1: (0.05-0.8).

To solve the second technical problem, the technical solution of the present invention is as follows: the preparation method of the catalyst for the catalytic oxidation of the pseudocumene 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 alkali metal elements, VIB group elements and nonmetal 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 sodium nitrate, sodium sulfate, sodium acetate, rubidium nitrate, rubidium sulfate and rubidium acetate. More preferred are sodium nitrate and rubidium nitrate. 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. The compound of the nonmetallic element in the step (1) is preferably at least one selected from silicon oxide, silicate, silicic acid, chlorosilane, borate and boric acid. Boric acid and trichlorosilane are more preferred.

In the technical scheme, the preparation method of the catalyst for the catalytic oxidation of 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 140-330 ℃.

In the technical scheme, the preparation method of the catalyst for the catalytic oxidation of the pseudocumene is characterized in that the carrier sprayed with the catalyst precursor is roasted in a muffle furnace, the roasting temperature is 420-630 ℃, and the roasting time is 2-13 h.

To solve the third technical problem, the technical scheme of the invention is as follows: the catalytic oxidation process of meta-anhydride uses 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^-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, alkali metal element and at least one element selected from VIB group element and nonmetal 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 66.9%, 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 VIB group elements and at least one element selected from nonmetal 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 ]

56g of oxalic acid and 192ml of distilled water are weighed in a flask, stirred and heated to 86 ℃, 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. The reaction is continued for 1h at 60 ℃ by adding 3 mole fractions of potassium nitrate and 0.4 mole fraction of chromium chloride into the solution. Adding 5 molar parts of titanium dioxide into 31ml 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 570 ℃ 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 2 ]

56g of oxalic acid and 192ml of distilled water are weighed in a flask, stirred and heated to 86 ℃, 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 mixing 3 mole fractions of potassium nitrate and 0.4 mole fractionBoric acid was added to the solution and the reaction was continued for 1h at 60 ℃. Adding 5 molar parts of titanium dioxide into 31ml 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 570 ℃ 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.

Comparative example 1

56g of oxalic acid and 192ml of distilled water are weighed in a flask, stirred and heated to 86 ℃, 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. The reaction was continued for 1h at 60 ℃ by adding 3 mole fraction potassium nitrate to the solution. Adding 5 molar parts of titanium dioxide into 31ml 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 570 ℃ 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 62.3 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 Na active components and higher yield of the partial anhydride, and contains V, Ti, Na and Cr active components simultaneously and V, Ti, Na and B active components simultaneously.

[ example 3 ]

56g of oxalic acid and 192ml of distilled water are weighed in a flask, stirred and heated to 86 ℃, 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. By adding 3 mole fractions of rubidium nitrate and 0.4 mole fraction of chromium nitrateThe reaction was continued in the solution at 60 ℃ for 1 h. Adding 5 molar parts of titanium tetrachloride into 31ml 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 570 ℃ 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 65.2 percent, the evaluation result is detailed in table 1.

[ example 4 ]

56g of oxalic acid and 192ml of distilled water are weighed in a flask, stirred and heated to 86 ℃, 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 3 mole fractions of rubidium nitrate and 0.4 mole fraction of molybdenum chloride into the solution, and continuing to react for 1 hour at 60 ℃. Adding 5 molar parts of titanium dioxide into 31ml 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 570 ℃ 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 5 ]

56g of oxalic acid and 192ml of distilled water are weighed in a flask, stirred and heated to 86 ℃, 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. Adding 3 mole fraction sodium acetate and 0.4 mole fraction ammonium molybdate into the solution, and continuing the reaction at 60 ℃ for 1 h. Adding 5 molar parts of titanium tetrachloride into 31ml 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 the mixture in a muffle furnace at the temperature of 570 ℃,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 ]

56g of oxalic acid and 192ml of distilled water are weighed in a flask, stirred and heated to 86 ℃, 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 3 mole fractions of rubidium nitrate and 0.4 mole fraction of ammonium borate into the solution, and continuing the reaction for 1 hour at 60 ℃. Adding 5 molar parts of titanium tetrachloride into 31ml 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 570 ℃ 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 7 ]

56g of oxalic acid and 192ml of distilled water are weighed in a flask, stirred and heated to 86 ℃, 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 3 mole fractions of rubidium acetate and 0.4 mole fraction of silicon chloride into the solution, and continuing the reaction for 1 hour at 60 ℃. Adding 5 molar parts of titanium dioxide into 31ml 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 570 ℃ 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 8 ]

56g of oxalic acid and 192ml of distilled water are weighed in a flask, stirred and heated to 86 ℃, 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. Adding 3 mole fractions of sodium acetate and 0.4 mole fraction of trichlorosilane into the solution, and continuing the reaction at 60 ℃ for 1 hour. Adding 5 molar parts of titanium tetrachloride into 31ml 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 570 ℃ 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 65.2 percent, the evaluation result is detailed in table 1.

[ example 9 ]

56g of oxalic acid and 192ml of distilled water are weighed in a flask, stirred and heated to 86 ℃, 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. Adding 3 mole fractions of sodium nitrate, 0.2 mole fraction of chromium chloride and 0.2 mole fraction of boric acid into the solution, and continuing the reaction at 60 ℃ for 1 h. Adding 5 molar parts of titanium dioxide into 31ml 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 570 ℃ 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 65.7 percent, the evaluation result is detailed in table 1.

Compared with the examples 1-2, the VIB group Cr element and the nonmetal B element have better synergistic effect on improving the yield of the partial anhydride.

[ example 10 ]

56g oxalic acid and 192ml distilled water were weighed into a flaskStirring and heating to 86 deg.c to dissolve oxalic acid completely to prepare oxalic acid solution. 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 parts of sodium nitrate, 0.1 mole part of chromium chloride, 0.1 mole part of ammonium molybdate and 0.2 mole part of boric acid into the solution, and continuing to react for 1 hour at the temperature of 60 ℃. Adding 5 molar parts of titanium dioxide into 31ml 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 570 ℃ 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 66.3% by evaluation in a fixed bed reactor, the evaluation results are detailed in table 1.

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

[ example 11 ]

56g of oxalic acid and 192ml of distilled water are weighed in a flask, stirred and heated to 86 ℃, 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. Adding 3 mole fractions of sodium nitrate, 0.2 mole fraction of chromium chloride, 0.1 mole fraction of boric acid and 0.1 mole fraction of trichlorosilane into the solution, and continuing to react for 1 hour at 60 ℃. Adding 5 molar parts of titanium dioxide into 31ml 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 570 ℃ 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 example 9, it can be seen that the nonmetal elements B and Si have better synergistic effect with other active components of the invention in improving the yield of the partial anhydride.

[ example 12 ]

56g of oxalic acid and 192ml of distilled water are weighed in a flask, stirred and heated to 86 ℃, 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. Adding 3 mole fractions of sodium nitrate, 0.2 mole fraction of ammonium molybdate, 0.1 mole fraction of boric acid and 0.1 mole fraction of trichlorosilane into the solution, and continuing to react for 1 hour at 60 ℃. Adding 5 molar parts of titanium dioxide into 31ml 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 570 ℃ 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.

[ example 13 ]

56g of oxalic acid and 192ml of distilled water are weighed in a flask, stirred and heated to 86 ℃, 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. Adding 3 mole fractions of sodium nitrate, 0.1 mole fraction of chromium chloride, 0.1 mole fraction of boric acid, 0.1 mole fraction of trichlorosilane into the solution, and continuously reacting for 1 hour at 60 ℃. Adding 5 molar parts of titanium dioxide into 31ml 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 570 ℃ 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 66.9% by evaluation in a fixed bed reactor, the evaluation results are detailed in table 1.

Compared with the examples 10 and 11, the present example shows that V, Ti, the alkali metals Na, the VIB group Cr and Mo elements, and the nonmetal B and Si elements have very good synergistic effect on improving the yield of the partial anhydride.

Comparative example 2

56g of oxalic acid and 192ml of distilled water are weighed in a flask, stirred and heated to 86 ℃, 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. 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 5 molar parts of titanium dioxide into 31ml 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 570 ℃ 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 63.4% by evaluation in a fixed bed reactor, the evaluation results are shown in table 1.

TABLE 1