Catalyst with durene oxidation function as well as preparation method and application thereof

Abstract

The invention relates to the technical field of pyromellitic dianhydride preparation, and discloses a catalyst with durene oxidation function and a preparation method and application thereof.The catalyst comprises a carrier and a coating loaded on the carrier, the coating comprises active components and a heat-resistant fiber material, and the active components comprise V, Cs, Ti, Nb, Sb, optional P and optional Zr. According to the catalyst containing the heat-resistant fiber material, the bonding strength of active components can be improved, the loss rate of the active components of a catalyst coating is reduced, and the situation that the service life of the catalyst is affected due to component loss is reduced.

Description

Technical Field

[0001] This invention relates to the field of homohydric anhydride preparation technology, specifically to a catalyst with homotetramethylbenzene oxidation function, its preparation method, and its application. Background Technology

[0002] 1,2,4,5-Phenylacetic dianhydride (hereinafter referred to as pyromellitic dianhydride) is a very important chemical raw material. Pyromellitic dianhydride and its derivatives have very important and wide applications, especially as one of the main monomers for the production of polyimide. Due to its comprehensive high-temperature performance, polyimide is currently the organic polymer material with the widest operating temperature range, and it is a new type of engineering material with excellent high-temperature dimensional stability, radiation resistance, mechanical properties, electrical properties, and corrosion resistance.

[0003] Early methods for producing pyromellitic dianhydride from mesitylene employed liquid-phase oxidation, where mesitylene was oxidized to an acid, which was then dehydrated to produce the dianhydride. In recent years, breakthroughs have been achieved in gas-phase oxidation: mesitylene can be oxidized in air in a single step to produce pyromellitic dianhydride. This method eliminates the catalyst separation step and is suitable for continuous industrial production. The catalysts used in this method are all V-based catalysts, with Ti / Mo / Fe elements also mentioned in the literature.

[0004] CN107866257A discloses a catalyst for the production of homohydric anhydride from mesitylene. It employs a V-based oxide catalyst, with the active component including at least one of V, Fe-based elements, and Group IIB elements and alkali metals. The support is α-Al₂O₃, silicon carbide, ceramic rings, or mixtures thereof.

[0005] The reaction conditions used for the oxidation of mesitylene to homohydric anhydride catalyst are 300-500℃. Under higher temperature reaction conditions, the catalyst coating will peel off, which can easily lead to a decrease in catalyst performance and a reduction in lifespan. Summary of the Invention

[0006] The purpose of this invention is to overcome the problem of easy detachment of the coating (active component) of the homogeneous anhydride catalyst in the prior art, and to provide a catalyst with homogeneous tetramethylbenzene oxidation function, its preparation method and application. The catalyst contains heat-resistant fiber material, which can enhance the bonding strength between active components and between active components and the support, reduce the detachment of active components in the coating, and thus improve the service life of the catalyst.

[0007] To achieve the above objectives, a first aspect of the present invention provides a catalyst having a mesitylene oxidation function, the catalyst comprising a support and a coating supported on the support, wherein the coating comprises an active component and a heat-resistant fiber material, the active component comprising V, Cs, Ti, Nb, Sb, optional P and optional Zr.

[0008] A second aspect of the present invention provides a method for preparing a catalyst with a mesitylene oxidation function. The method includes coating a slurry containing an active component precursor and a heat-resistant fiber material onto a support to form a coating on the support. The active component precursor includes a vanadium precursor, a cesium precursor, a titanium precursor, a niobium precursor, an antimony precursor, and optionally a phosphorus precursor and an optional zirconium precursor.

[0009] A third aspect of the present invention provides a catalyst prepared by the above method.

[0010] A fourth aspect of the present invention provides a reactor packed with a catalyst, wherein the reactor is packed with at least one catalyst bed, and the at least one catalyst bed is packed with the catalyst described above.

[0011] The fifth aspect of the present invention provides a method for producing homohydric anhydride, the method comprising: contacting mesitylene with an oxygen-containing gas in the presence of the catalyst described above;

[0012] Alternatively, the method may include: preparing a catalyst according to the method described above, and then contacting mesitylene with an oxygen-containing gas in the presence of the catalyst;

[0013] Alternatively, the method may include introducing mesitylene into the reactor described above to contact it with an oxygen-containing gas.

[0014] The catalyst containing heat-resistant fiber material of the present invention can improve the bonding strength of the active components, reduce the loss rate of active components in the catalyst coating, and reduce the impact of component loss on the service life of the catalyst.

[0015] This invention enhances the bonding strength of active components by adding ultrafine heat-resistant fiber materials to the slurry, reduces the loss rate of active components in the coating, and thus extends the service life of the catalyst. Detailed Implementation

[0016] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0017] The first aspect of the present invention provides a catalyst having a mesitylene oxidation function, the catalyst comprising a support and a coating supported on the support, wherein the coating comprises an active component and a heat-resistant fiber material, the active component comprising V, Cs, Ti, Nb, Sb, optional P and optional Zr.

[0018] In this invention, heat-resistant fiber materials generally refer to fiber materials that can basically maintain their original physical and mechanical properties at 300-500℃.

[0019] In this invention, the heat-resistant fiber material used can be ultrafine glass fiber. Preferably, the length of the glass fiber is 20-50 μm (e.g., 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, and any two of the above), more preferably 20-40 μm; the aspect ratio is 20-100 (e.g., 20, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, and any two of the above), more preferably 30-80. When the length and aspect ratio of the glass fiber are limited to the above ranges, not only can the yield of homogenized anhydride be guaranteed, but the loss rate of active components in the coating can also be reduced. In this invention, the diameter of the glass fiber can be 0.5-1 μm.

[0020] In this invention, the length and diameter of the fibers are measured using scanning electron microscopy (SEM). Specifically, several glass fibers are randomly selected for SEM testing. The length and diameter of 20 glass fibers within the field of view are then observed, and the average value is calculated. The average length is taken as the length of the glass fiber, and the average diameter is taken as the diameter of the glass fiber. Aspect ratio = average length / average diameter.

[0021] According to the present invention, preferably, the weight ratio of coating to carrier is 10-20:100, more preferably 12-18:100.

[0022] According to the present invention, preferably, the molar ratio of V, Cs, Ti, Nb, Sb, P and Zr is 0.05-0.08:0.001-0.005:1:0.0001-0.002:0.01-0.02:0-0.01:0-0.01.

[0023] According to the present invention, preferably, the weight ratio of heat-resistant fiber material to Ti is 0.02-0.04:1.

[0024] In this invention, the proportions of each component in the catalyst are calculated based on the amount of feed.

[0025] According to the present invention, the type of carrier is not particularly limited and can be selected from a wide range. Preferably, the carrier is selected from at least one of talc, silicon carbide, aluminum silicate, quartz, and ceramics.

[0026] In this invention, there is no particular limitation on the shape of the carrier; for example, it can be cylindrical, spherical, annular, or granular. Preferably, the carrier is an annular carrier.

[0027] In some embodiments of the present invention, preferably, the outer diameter of the carrier is 3-13 mm, for example, 3 mm, 5 mm, 7 mm, 9 mm, 11 mm, 13 mm, and any two of the above-mentioned points, preferably 5-9 mm; the height is 2-12 mm, for example, 2 mm, 3 mm, 5 mm, 7 mm, 8 mm, 10 mm, 12 mm, and any two of the above-mentioned points, preferably 3-8 mm; the wall thickness is 0.1-10 mm, preferably 0.1-5 mm.

[0028] A second aspect of the present invention provides a method for preparing a catalyst with a mesitylene oxidation function. The method includes coating a slurry containing an active component precursor and a heat-resistant fiber material onto a support to form a coating on the support. The active component precursor includes a vanadium precursor, a cesium precursor, a titanium precursor, a niobium precursor, an antimony precursor, and optionally a phosphorus precursor and an optional zirconium precursor.

[0029] In this invention, the heat-resistant fiber material used can be ultra-long glass fibers. Preferably, the length of the glass fiber is 20-50 μm, and the aspect ratio is 20-100. When the length and aspect ratio of the glass fiber or ceramic fiber are limited to the above ranges, the loss rate of the active component in the coating can be reduced while ensuring the yield of homogenized anhydride. In this invention, the diameter of the glass fiber is 0.5-1 μm. The methods for measuring the length and diameter of the fiber are as described above.

[0030] According to the present invention, preferably, the content of the active component precursor in the slurry is 40-60% by weight, more preferably 45-55% by weight; and the content of the heat-resistant fiber material is 0.01-10% by weight, more preferably 0.5-1% by weight.

[0031] According to the present invention, preferably, relative to 630g of titanium precursor, the amount of vanadium precursor is 50-70g, the amount of cesium precursor is 1.9-3.5g, the amount of niobium precursor is 3.5-5.5g, the amount of antimony precursor is 10-20g, the amount of phosphorus precursor is 0-5g, and the amount of zirconium precursor is 0-5g.

[0032] According to the present invention, preferably, the amount of the support, the active component precursor and the heat-resistant fiber material is such that the weight ratio of the coating to the support in the obtained catalyst is 10-20:100, preferably 12-18:100.

[0033] According to the present invention, preferably, the method for obtaining the slurry containing the active component precursor and the heat-resistant fiber material includes the following steps:

[0034] (1) A solution is obtained by mixing a reducing agent (e.g., oxalic acid), a vanadium precursor, a cesium precursor, an optional phosphorus precursor, and a solvent;

[0035] (2) The solution obtained in step (1) is mixed with titanium precursor, niobium precursor, antimony precursor, optional zirconium precursor, binder and heat-resistant fiber material to obtain slurry.

[0036] According to the present invention, preferably, the vanadium precursor is selected from ammonium metavanadate and / or vanadium pentoxide.

[0037] According to the present invention, preferably, the cesium precursor is selected from at least one of cesium nitrate, cesium sulfate and cesium chloride.

[0038] According to the present invention, preferably, the phosphorus precursor is selected from at least one of ammonium dihydrogen phosphate, triammonium phosphate, and phosphorus pentoxide.

[0039] According to the present invention, preferably, the amount of solvent used is 590-600g relative to 630g of titanium precursor.

[0040] According to the present invention, preferably, the amount of reducing agent is 110-150g relative to 630g of titanium precursor.

[0041] According to the present invention, preferably, the amount of adhesive used is 65-100g relative to 630g of titanium precursor.

[0042] According to the present invention, preferably, the solvent is a mixture of water and a water-soluble organic solvent, wherein the water-soluble organic solvent may be selected from at least one of methanol, ethanol, formamide and N,N-dimethylamide; the mass ratio of the water-soluble organic solvent to water is 0.1-1:1, more preferably 0.1-0.7:1.

[0043] According to the present invention, preferably, the titanium precursor is selected from titanium dioxide, more preferably, the titanium dioxide is anatase titanium dioxide. The specific surface area of ​​the anatase titanium dioxide can be 10 m². 2 / g-30m 2 / g, more preferably 15m 2 / g-25m 2 / g.

[0044] In this invention, the antimony precursor can be selected from antimony oxide and / or antimony sulfate, preferably antimony oxide.

[0045] In this invention, the niobium precursor may be selected from niobium oxalate and / or niobium sulfate, preferably niobium oxalate.

[0046] In this invention, the zirconium precursor may be selected from zirconium sulfate and / or zirconium oxide, preferably zirconium sulfate.

[0047] According to the present invention, preferably, the adhesive is an emulsion of at least one selected from vinyl acetate-acrylate copolymer, vinyl acetate-ethylene copolymer, vinyl acetate-cis-butadiene copolymer, and acrylic acid-maleic acid copolymer.

[0048] According to the present invention, there is no particular limitation on the mixing method. Wet grinding can be used to combine the convenience and timeliness of grinding. Preferably, in step (2), the mixing is completed in a ball mill. More preferably, the grinding time in the ball mill is 1-5 hours, and even more preferably 2-4 hours.

[0049] According to the present invention, in order to more uniformly coat the slurry onto the carrier, the viscosity of the slurry is preferably 10-40 mPa·s, for example, 10 mPa·s, 12 mPa·s, 15 mPa·s, 20 mPa·s, 25 mPa·s, 30 mPa·s, 35 mPa·s, 40 mPa·s, and more preferably 12-25 mPa·s. In this invention, unless otherwise specified, the viscosity parameter is measured using a cup viscometer (25°C).

[0050] According to the present invention, preferably, the spraying speed of the slurry is 60-120 mL / min relative to each 2000 g carrier.

[0051] According to the present invention, the device used for spraying is not particularly limited, as long as it can meet the needs of spraying. Preferably, the device used for spraying includes a hot air blower, a coating host, an exhaust fan, a slurry spraying system, a control system, and a high-voltage power supply cabinet. The coating host includes a coating drum and its power mechanism. The coating drum is enclosed inside the coating host, and its rotation speed can be adjusted. The coating drum adopts a horizontal hollow columnar structure, which can improve the contact opportunity between the active component precursor and the inert carrier material. Circular mesh with a diameter of 1-8 mm, preferably 3-4 mm, is opened on the horizontal hollow columnar structure. The purpose is to ensure that hot air penetrates into the coating drum, evaporates the solvent in the slurry on the carrier, and then exits the coating drum to carry away the solvent. Preferably, the rotation speed of the coating drum is 5-10 rpm. The slurry spraying system consists of nozzles and a feeding system. The feeding system consists of a material tank, a mixer, a feeding pump, and a conveying pipeline. The feed pump can adjust the spraying rate, and the nozzle can ensure that the slurry can be evenly sprayed onto the surface of the inert carrier material after passing through the feed pump, forming a smooth and flat coating of catalytic active material, thus preparing the catalyst.

[0052] According to the present invention, preferably, the coating temperature is 200-250°C. The coating temperature is the temperature of the hot air used in the coating process. At the end of the coating process, the carrier weight gain is 10-20 wt% (preferably 12-18 wt%). It is understood that the carrier weight gain refers to the percentage of the weight of the coating applied to the carrier relative to the weight of the carrier.

[0053] According to the present invention, the type of carrier is not particularly limited and can be selected from a wide range. Preferably, the carrier is selected from at least one of talc, silicon carbide, aluminum silicate, quartz, and ceramics. The shape of the carrier is as defined above, and will not be elaborated here.

[0054] A third aspect of the present invention provides a catalyst prepared by the above method.

[0055] A fourth aspect of the present invention provides a reactor packed with a catalyst, wherein the reactor is packed with at least one catalyst bed, and the at least one catalyst bed is packed with the catalyst described above.

[0056] According to the present invention, preferably, the reactor is filled with two catalyst beds, both of which are filled with the catalyst described above, wherein the catalyst in the first catalyst bed does not contain P and Zr, and the catalyst in the second catalyst bed contains P and Zr.

[0057] According to the present invention, preferably, the ratio of the height of the catalyst packed in the first catalyst bed to the height of the catalyst packed in the second catalyst bed is 1:0.5-2. Mesitylene first contacts the second catalyst bed, and then contacts the first catalyst bed.

[0058] The fifth aspect of the present invention provides a method for producing homohydric anhydride, the method comprising: contacting mesitylene with an oxygen-containing gas in the presence of the catalyst described above;

[0059] Alternatively, the method may include: preparing a catalyst according to the method described above, and then contacting mesitylene with an oxygen-containing gas in the presence of the catalyst;

[0060] Alternatively, the method may include introducing mesitylene into the reactor described above to contact it with an oxygen-containing gas.

[0061] According to the present invention, preferably, the contact conditions include: a heating temperature of 340-380°C; and an oxygen-containing gas volume hourly space velocity of 1500-6000 h⁻¹. -1 More preferably 2000-4000h -1 The concentration of mesitylene is 20-30 g / m³. 3 In this invention, the pressure of the reaction can be negative pressure, normal pressure, or pressurized pressure, preferably normal pressure.

[0062] According to the present invention, preferably, the oxygen-containing gas is air.

[0063] In this invention, the concentration of mesitylene refers to the number of grams of mesitylene contained in a unit volume of air. The higher the value, the higher the content of mesitylene in the air.

[0064] This invention utilizes a fixed-bed reactor and employs molten salt circulation for heat exchange. During the reaction evaluation, a temperature distribution exists within the catalyst bed, with the highest temperature value in the region termed the hot spot temperature. This invention uses thermocouples to measure the bed temperature.

[0065] According to the present invention, preferably, the method for producing homohydric anhydride further includes activating the catalyst prior to the contact reaction. More preferably, the activation conditions include activation in an oxidizing atmosphere for 4-24 hours; more preferably, the activation temperature is 300-500°C.

[0066] The present invention will be described in detail below through embodiments. In the following embodiments,

[0067] The carrier is a talc ring.

[0068] The titanium dioxide is anatase titanium dioxide with a specific surface area of ​​20-25 m². 2 / g.

[0069] The catalytic products were analyzed using chromatographic methods.

[0070] The formula for calculating the conversion rate (%) of mesitylene is:

[0071]

[0072] The formula for calculating the weight yield (%) of homogeneous anhydride is:

[0073]

[0074] The content of each component in the catalyst coatings prepared in the examples and comparative examples was calculated by the amount of feed.

[0075] Example 1

[0076] Preparation of catalyst A:

[0077] (1) Dissolve 57.87g ammonium metavanadate, 130.65g oxalic acid, 3.18g cesium sulfate, and 220mL formamide in 350g water to make a solution. The mass ratio of formamide to water is 0.7:1.

[0078] (2) Pour the solution, 630g of titanium dioxide, 10g of glass fiber (the glass fiber has a length of 20μm and an aspect ratio of 40), 5.1g of niobium oxalate, and 12.74g of antimony trioxide into a ball mill, add 70g of vinyl acetate / ethylene copolymer emulsion, and ball mill for 4h to emulsify the active component precursor into a uniform suspension emulsion.

[0079] (3) Place 2000g of a carrier magnetic ring with an outer diameter of 8mm, a height of 6mm, and a wall thickness of 1.5mm in a rotating drum, and control the drum speed at 10rpm; add the above-prepared suspension emulsion to the mixing tank of the liquid spraying system and stir; turn on the hot air blower, and hot air enters the rotating drum to preheat the carrier magnetic ring. The suspension emulsion is sprayed onto the surface of the carrier magnetic ring through the nozzle and dried rapidly by the hot air. When the carrier temperature reaches 100℃, turn on the feed nozzle, control the hot air temperature at 220℃, and the liquid spraying rate at 80mL / min. The final total weight gain of the carrier is 14.3% by weight. The spraying is completed, and catalyst A is obtained.

[0080] Preparation of catalyst B:

[0081] (1) Dissolve 65.63g ammonium metavanadate, 152.32g oxalic acid, 2.25g cesium sulfate, 4.16g ammonium dihydrogen phosphate, and 220mL formamide in 350g water to make a solution. The mass ratio of formamide to water is 0.7:1.

[0082] (2) The solution, 630g of titanium dioxide, 15g of glass fiber (the glass fiber is 20μm long and the aspect ratio is 40), 18.35g of antimony trioxide, 3.78g of niobium oxalate, and 3.72g of zirconium sulfate tetrahydrate were poured into a ball mill. 100g of vinyl acetate / ethylene copolymer emulsion was added. The mixture was ball-milled for 4 hours to emulsify the active component precursor into a uniform suspension emulsion.

[0083] (3) A 2000g carrier magnetic ring with an outer diameter of 8mm, a height of 6mm, and a wall thickness of 1.5mm was placed in a rotating drum, and the drum speed was controlled at 10rpm. The suspension emulsion prepared above was added to the mixing tank of the liquid spraying system and stirred. The hot air was turned on, and hot air was introduced into the rotating drum to preheat the carrier magnetic ring. The suspension emulsion was sprayed onto the surface of the carrier magnetic ring through the nozzle and dried rapidly by the hot air. When the carrier temperature reached 110℃, the feed nozzle was turned on, and the hot air temperature was controlled at 230℃. The liquid spraying rate was 60mL / min, and the spraying time resulted in a carrier weight gain of 16.1% by weight. After the spraying was completed, catalyst B was obtained.

[0084] Example 2

[0085] Preparation of catalyst A:

[0086] (1) Dissolve 57.87g ammonium metavanadate, 130.65g oxalic acid, 3.18g cesium sulfate, and 220mL formamide in 350g water to make a solution. The mass ratio of formamide to water is 0.7:1.

[0087] (2) Pour the solution, 630g of titanium dioxide, 10g of glass fiber (the glass fiber has a length of 20μm and an aspect ratio of 40), 5.1g of niobium oxalate, and 12.74g of antimony trioxide into a ball mill, add 70g of vinyl acetate / ethylene copolymer emulsion, and ball mill for 4h to emulsify the active component precursor into a uniform suspension emulsion.

[0088] (3) Place 2000g of a carrier magnetic ring with an outer diameter of 8mm, a height of 6mm, and a wall thickness of 1.5mm in a rotating drum, and control the drum speed at 10rpm; add the above-prepared suspension emulsion to the mixing tank of the liquid spraying system and stir; turn on the hot air blower, and hot air enters the rotating drum to preheat the carrier magnetic ring. The suspension emulsion is sprayed onto the surface of the carrier magnetic ring through the nozzle and dried rapidly by the hot air. When the carrier temperature reaches 100℃, turn on the feed nozzle, control the hot air temperature at 210℃, and the liquid spraying rate at 70mL / min. The final total weight gain of the carrier is 14.2% by weight. The spraying is completed, and catalyst A is obtained.

[0089] Preparation of catalyst B:

[0090] (1) Dissolve 68.33g ammonium metavanadate, 163.27g oxalic acid, 2.19g cesium sulfate, 4.28g ammonium dihydrogen phosphate, and 220mL formamide in 350g water to make a solution. The mass ratio of formamide to water is 0.7:1.

[0091] (2) The solution, 630g of titanium dioxide, 15g of glass fiber (the glass fiber is 20μm long and the aspect ratio is 40), 19.87g of antimony trioxide, 3.99g of niobium oxalate, and 4.22g of zirconium sulfate tetrahydrate were poured into a ball mill. 100g of vinyl acetate / ethylene copolymer emulsion was added. The mixture was ball-milled for 4 hours to emulsify the active component precursor into a uniform suspension emulsion.

[0092] (3) Place 2000g of a carrier magnetic ring with an outer diameter of 8mm, a height of 6mm, and a wall thickness of 1.5mm in a rotating drum, and control the drum speed at 10rpm; add the above-prepared suspension emulsion to the mixing tank of the liquid spraying system and stir; turn on the hot air blower, and hot air enters the rotating drum to preheat the carrier magnetic ring. The suspension emulsion is sprayed onto the surface of the carrier magnetic ring through the nozzle and dried rapidly by the hot air. When the carrier temperature reaches 110℃, turn on the feed nozzle, control the hot air temperature at 220℃, and the liquid spraying rate at 90mL / min. The spraying time results in a carrier weight gain of 16.5% by weight. After spraying is completed, catalyst B is obtained.

[0093] Example 3

[0094] Preparation of catalyst A:

[0095] (1) Dissolve 52.39g ammonium metavanadate, 121.65g oxalic acid, 3.11g cesium sulfate, and 220mL formamide in 350g water to make a solution. The mass ratio of formamide to water is 0.7:1.

[0096] (2) The solution, 630g of titanium dioxide, 10g of glass fiber (the glass fiber is 20μm long and the aspect ratio is 40), 4.96g of niobium oxalate, and 11.87g of antimony trioxide were poured into a ball mill. 70g of vinyl acetate / ethylene copolymer emulsion was added. The mixture was ball milled for 4 hours to emulsify the active component precursor into a uniform suspension emulsion.

[0097] (3) Place 2000g of a carrier magnetic ring with an outer diameter of 8mm, a height of 6mm, and a wall thickness of 1.5mm in a rotating drum, and control the drum speed at 10rpm; add the above-prepared suspension emulsion to the mixing tank of the liquid spraying system and stir; turn on the hot air blower, and hot air enters the rotating drum to preheat the carrier magnetic ring. The suspension emulsion is sprayed onto the surface of the carrier magnetic ring through the nozzle and dried rapidly by the hot air. When the carrier temperature reaches 100℃, turn on the feed nozzle, control the hot air temperature at 230℃, and the liquid spraying rate at 75mL / min. The final total weight gain of the carrier is 14.7% by weight. The spraying is completed, and catalyst A is obtained.

[0098] Preparation of catalyst B:

[0099] (1) Dissolve 65.63g ammonium metavanadate, 152.32g oxalic acid, 2.25g cesium sulfate, 4.16g ammonium dihydrogen phosphate, and 220mL formamide in 350g water to make a solution. The mass ratio of formamide to water is 0.7:1.

[0100] (2) The solution, 630g of titanium dioxide, 15g of glass fiber (the glass fiber is 20μm long and the aspect ratio is 40), 18.35g of antimony trioxide, 3.78g of niobium oxalate, and 3.72g of zirconium sulfate tetrahydrate were poured into a ball mill. 100g of vinyl acetate / ethylene copolymer emulsion was added. The mixture was ball-milled for 4 hours to emulsify the active component precursor into a uniform suspension emulsion.

[0101] (3) A 2000g carrier magnetic ring with an outer diameter of 8mm, a height of 6mm, and a wall thickness of 1.5mm was placed in a rotating drum, and the drum speed was controlled at 10rpm. The suspension emulsion prepared above was added to the mixing tank of the liquid spraying system and stirred. The hot air was turned on, and hot air was introduced into the rotating drum to preheat the carrier magnetic ring. The suspension emulsion was sprayed onto the surface of the carrier magnetic ring through the nozzle and dried rapidly by the hot air. When the carrier temperature reached 110℃, the feed nozzle was turned on, and the hot air temperature was controlled at 230℃. The liquid spraying rate was 65mL / min, and the spraying time resulted in a carrier weight gain of 16.3% by weight. After the spraying was completed, catalyst B was obtained.

[0102] Example 4

[0103] Preparation of catalyst A:

[0104] (1) Dissolve 52.39g ammonium metavanadate, 121.65g oxalic acid, 3.11g cesium sulfate, and 220mL formamide in 350g water to make a solution. The mass ratio of formamide to water is 0.7:1.

[0105] (2) The solution, 630g of titanium dioxide, 10g of glass fiber (the glass fiber is 20μm long and the aspect ratio is 40), 4.96g of niobium oxalate, and 11.87g of antimony trioxide were poured into a ball mill. 70g of vinyl acetate / ethylene copolymer emulsion was added. The mixture was ball milled for 4 hours to emulsify the active component precursor into a uniform suspension emulsion.

[0106] (3) Place 2000g of a carrier magnetic ring with an outer diameter of 8mm, a height of 6mm, and a wall thickness of 1.5mm in a rotating drum, and control the drum speed at 10rpm; add the above-prepared suspension emulsion to the mixing tank of the liquid spraying system and stir; turn on the hot air blower, and hot air enters the rotating drum to preheat the carrier magnetic ring. The suspension emulsion is sprayed onto the surface of the carrier magnetic ring through the nozzle and dried rapidly by the hot air. When the carrier temperature reaches 100℃, turn on the feed nozzle, control the hot air temperature at 230℃, and the liquid spraying rate at 75mL / min. The final total weight gain of the carrier is 14.7% by weight. The spraying is completed, and catalyst A is obtained.

[0107] Preparation of catalyst B:

[0108] (1) Dissolve 68.33g ammonium metavanadate, 163.27g oxalic acid, 2.19g cesium sulfate, 4.28g ammonium dihydrogen phosphate, and 220mL formamide in 350g water to make a solution. The mass ratio of formamide to water is 0.7:1.

[0109] (2) The solution, 630g of titanium dioxide, 15g of glass fiber (the glass fiber is 20μm long and the aspect ratio is 40), 19.87g of antimony trioxide, 3.99g of niobium oxalate, and 4.22g of zirconium sulfate tetrahydrate were poured into a ball mill. 100g of vinyl acetate / ethylene copolymer emulsion was added. The mixture was ball-milled for 4 hours to emulsify the active component precursor into a uniform suspension emulsion.

[0110] (3) A 2000g carrier magnetic ring with an outer diameter of 8mm, a height of 6mm, and a wall thickness of 1.5mm was placed in a rotating drum, and the drum speed was controlled at 10rpm. The suspension emulsion prepared above was added to the mixing tank of the liquid spraying system and stirred. The hot air was turned on, and hot air was introduced into the rotating drum to preheat the carrier magnetic ring. The suspension emulsion was sprayed onto the surface of the carrier magnetic ring through the nozzle and dried rapidly by the hot air. When the carrier temperature reached 110℃, the feed nozzle was turned on, and the hot air temperature was controlled at 230℃. The liquid spraying rate was 100mL / min, and the spraying time resulted in a carrier weight gain of 16.7% by weight. After the spraying was completed, catalyst B was obtained.

[0111] Example 5

[0112] The catalyst was prepared according to the preparation process of catalyst A and catalyst B in Example 4, except that the glass fiber was replaced with ultra-long glass fiber, wherein the length of the ultra-long glass fiber was 50 μm and the aspect ratio was 100.

[0113] Example 6

[0114] The catalyst was prepared according to the preparation process of catalyst A and catalyst B in Example 4, except that glass fiber was replaced with carbon fiber, wherein the length of the carbon fiber was 20 μm and the aspect ratio was 40.

[0115] Comparative Example 1

[0116] Preparation of catalyst A and catalyst B:

[0117] The catalyst was prepared according to the preparation process of catalyst A and catalyst B in Example 1, except that glass fiber was not added.

[0118] Comparative Example 2

[0119] Preparation of catalyst A and catalyst B:

[0120] The catalyst was prepared according to the preparation process of catalyst A and catalyst B in Example 4, except that glass fiber was not added.

[0121] Test Example 1

[0122] Catalyst performance was evaluated using a single-tube reactor simulating industrial production conditions. The fixed-bed single-tube reactor had an inner diameter of 29 mm and a tube length of 4400 mm. Molten salt circulation was used for heat transfer outside the reactor tube, while multiple temperature monitoring systems were installed inside. The catalyst was loaded in a two-stage manner, with catalyst B and catalyst A loaded from bottom to top. The loading height of catalyst B was 800 mm, and the loading height of catalyst A was 1200 mm. The reactor outlet was connected to an analysis system and a reactant collection system.

[0123] The catalysts prepared in the above examples and comparative examples were loaded as described above and activated at 410°C for 4 hours in an oxidizing atmosphere (air atmosphere). Then, mesitylene and air were introduced into the reactor from bottom to top at atmospheric pressure and an air space velocity of 1500 h⁻¹. -1 Within 100 hours, the concentration of mesitylene in the feed was increased to the concentration shown in Table 1. After another 10 hours of reaction, samples were taken at the reactor outlet for analysis to assess the yield of homogeneous anhydride under the highest load. The test results are listed in Table 1.

[0124] Table 1

[0125]

[0126] Test Example 2: Catalyst Coating Loss Rate

[0127] The catalyst coating loss rate of the catalysts in the examples and comparative examples was tested, and the specific method was as follows:

[0128] 1) Take 20 fresh catalyst particles (fresh catalyst refers to the catalyst obtained after spraying, the same below), weigh them, drop them once from top to bottom in a 3-meter-high pipe, and weigh them again to calculate the coating loss rate. The test results are shown in Table 2.

[0129] 2) Take 20 fresh catalyst particles from 4 groups and heat-treat them at 340℃ for 4h, 8h, 24h, and 48h in air atmosphere, respectively. After heat treatment, weigh them and drop them once from top to bottom in a 3-meter-high tube, and weigh them again to calculate the coating loss rate. The test results are shown in Table 3.

[0130] 3) Take 20 fresh catalyst particles from 4 groups and heat-treat them at 380℃ for 4h, 8h, 24h, and 48h in air atmosphere, respectively. After heat treatment, weigh them and drop them once from top to bottom in a 3-meter-high tube, then weigh them again to calculate the coating loss rate. The test results are shown in Table 3.

[0131] Active coating loss rate = (M1-M2) / M1×100%

[0132] Where M1 is the weight of the catalyst before it fell, and M2 is the weight of the catalyst after it fell.

[0133] Table 2

[0134]

[0135]

[0136] Table 3

[0137]

[0138]

[0139] As can be seen from Tables 1-3, the catalyst of the present invention can reduce the loss rate of catalyst coating while ensuring the yield of homogeneous anhydride.

[0140] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A catalyst with mesitylene oxidation function, characterized in that, The catalyst includes a support and a coating supported on the support, wherein the coating includes an active component and a heat-resistant fiber material, the active component including V, Cs, Ti, Nb, Sb, optional P and optional Zr.

2. The catalyst according to claim 1, wherein, The heat-resistant fiber material is glass fiber; Preferably, the glass fiber has a length of 20-50 μm and an aspect ratio of 20-100.

3. The catalyst according to claim 1 or 2, wherein, The weight ratio of coating to carrier is 10-20:100, preferably 12-18:100; And / or, the molar ratio of V, Cs, Ti, Nb, Sb, P and Zr is 0.05-0.08:0.001-0.005:1:0.0001-0.002:0.01-0.02:0-0.01:0-0.01; And / or, the weight ratio of heat-resistant fiber material to Ti is 0.02-0.04:1; And / or, the carrier is selected from at least one of talc, silicon carbide, aluminum silicate, quartz and ceramics.

4. A method for preparing a catalyst with mesitylene oxidation function, characterized in that, The method includes coating a slurry containing an active component precursor and a heat-resistant fiber material onto a carrier to form a coating on the carrier. The active component precursor includes a vanadium precursor, a cesium precursor, a titanium precursor, a niobium precursor, an antimony precursor, and optionally a phosphorus precursor and an optional zirconium precursor.

5. The method according to claim 4, wherein, The heat-resistant fiber material is glass fiber; Preferably, the glass fiber has a length of 20-50 μm and an aspect ratio of 20-100.

6. The method according to claim 4, wherein, The content of the active component precursor in the slurry is 40-60% by weight, preferably 45-55% by weight; the content of the heat-resistant fiber material is 0.01-10% by weight, preferably 0.5-1% by weight. And / or, relative to 630g of titanium precursor, the amount of vanadium precursor used is 50-70g, the amount of cesium precursor used is 1.9-3.5g, the amount of niobium precursor used is 3.5-5.5g, the amount of antimony precursor used is 10-20g, the amount of phosphorus precursor used is 0-5g, and the amount of zirconium precursor used is 0-5g.

7. The method according to claim 4, wherein, The coating temperature is 200-250℃; And / or, the amount of the support, active component precursor and heat-resistant fiber material is such that the weight ratio of coating to support in the obtained catalyst is 10-20:100, preferably 12-18:100; And / or, the carrier is selected from at least one of talc, silicon carbide, aluminum silicate, quartz and ceramics.

8. The method according to any one of claims 4-7, wherein, The method for obtaining a slurry containing an active component precursor and a heat-resistant fiber material includes the following steps: (1) A solution is obtained by mixing a reducing agent, a vanadium precursor, a cesium precursor, an optional phosphorus precursor, and a solvent; (2) The solution obtained in step (1) is mixed with titanium precursor, niobium precursor, antimony precursor, optional zirconium precursor, binder and heat-resistant fiber material to obtain slurry.

9. The catalyst prepared by the method according to any one of claims 4-8.

10. A reactor filled with a catalyst, characterized in that, The reactor is packed with at least one catalyst bed, which is packed with the catalyst according to any one of claims 1-3 and 9.

11. The reactor according to claim 10, wherein, The reactor is filled with two catalyst beds, each containing the catalyst described in any one of claims 1-3 and 9, wherein the catalyst in the first catalyst bed does not contain P and Zr, and the catalyst in the second catalyst bed contains P and Zr.

12. A method for producing homogenizing anhydride, characterized in that, The method comprises: contacting mesitylene with an oxygen-containing gas in the presence of the catalyst described in any one of claims 1-3 and 9; Alternatively, the method may include: preparing a catalyst according to any one of claims 4-8, and then contacting mesitylene with an oxygen-containing gas in the presence of the catalyst; Alternatively, the method may include: introducing mesitylene into the reactor of claim 10 or 11 to contact it with an oxygen-containing gas.

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