Catalyst for preparing homomalic anhydride, process for its preparation and use

Abstract

This invention relates to the field of homohydric anhydride preparation by the oxidation of mesitylene, and discloses a catalyst for preparing homohydric anhydride, its preparation method, and its application. The catalyst comprises a support and an active component supported on the support. The active component includes a main active component and auxiliary active components. The main active component includes oxides of vanadium, oxides of cesium, micron-sized titanium dioxide, and nano-sized titanium dioxide. The auxiliary active components include oxides of at least one element selected from rubidium, cerium, niobium, chromium, tungsten, silver, cobalt, gallium, indium, antimony, bismuth, zirconium, and erbium. The specific surface area of ​​the micron-sized titanium dioxide is 10 m². 2 / g-30m 2 / g, the specific surface area of ​​nano-titanium oxide is 50m². 2 / g-100m 2 / g. The catalyst containing micron-sized and nano-sized titanium dioxide of this invention can be rapidly activated, increasing the concentration of mesitylene to 58 g / Nm³ within 2 hours. 3 In addition, this can also improve the yield of homogenate.

Description

Technical Field

[0001] This invention relates to the field of homotoluene oxidation for homotoluene preparation, specifically to a catalyst for homotoluene preparation, 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 preparing pyromellitic dianhydride from mesitylene primarily employed a liquid-phase oxidation process. The raw material was oxidized in the liquid phase to produce an acid, which was then dehydrated to produce the anhydride. Currently, the commonly used method involves a one-step air oxidation process using mesitylene as a raw material to obtain pyromellitic dianhydride. This method is characterized by its simplicity, eliminating the dehydration step to anhydride, using air as the oxidant, eliminating the need for catalyst separation in liquid-phase oxidation, allowing for continuous production, and facilitating automation.

[0004] Existing catalysts for preparing pyromellitic dianhydride are mostly composed of oxides of elements such as V, Ti, Mo, and Fe. Chinese patent CN107866241A discloses a catalyst for the oxidation of pyromellitic dianhydride to pyromellitic dianhydride, employing an oxide catalyst. The catalyst uses α-Al₂O₃, silicon carbide, ceramic rings, or mixtures thereof as a support, and the active components include vanadium, titanium, and at least one element selected from group VA and alkali metals. However, this catalyst suffers from low bed utilization and low yield.

[0005] Chinese patent CN107866257A discloses a catalyst for the production of homohydric anhydride from mesitylene. It employs an oxide catalyst, using α-Al₂O₃, silicon carbide, ceramic rings, or mixtures thereof as a support. The active component includes vanadium, iron-based elements, and at least one of Group IIB elements and alkali metals. However, this catalyst also suffers from drawbacks such as a lack of catalyst bed design and low yield.

[0006] The oxidation of mesitylene to homohydric anhydride requires a certain temperature to activate, resulting in a section of catalyst at the inlet of the catalyst bed where the reaction efficiency is very low due to insufficient temperature. Improving the utilization efficiency of this section of catalyst, and thus the overall utilization efficiency of the catalyst bed, is a technical problem that needs to be solved. Summary of the Invention

[0007] The purpose of this invention is to overcome the above-mentioned technical problems and provide a catalyst for preparing homohydric anhydride, its preparation method, and its application.

[0008] To achieve the above objectives, the first aspect of the present invention provides a catalyst for preparing homohydric anhydride, the catalyst comprising a support and an active component supported on the support, wherein the active component comprises a main active component and an auxiliary active component, the main active component comprising vanadium oxide, cesium oxide, micron-sized titanium oxide and nano-sized titanium oxide, and the auxiliary active component comprising an oxide of at least one of rubidium, cerium, niobium, chromium, tungsten, silver, cobalt, gallium, indium, antimony, bismuth, zirconium and erbium;

[0009] Among them, the specific surface area of ​​micron-sized titanium oxide is 10m². 2 / g-30m 2 / g, the specific surface area of ​​nano-titanium oxide is 50m². 2 / g-100m 2 / g.

[0010] The second aspect of the present invention provides a method for preparing a homogeneous anhydride catalyst, the method comprising: loading a main active component and an auxiliary active component onto a support, wherein the main active component includes oxides of vanadium, oxides of cesium, micron-sized titanium dioxide and nano-sized titanium dioxide, and the auxiliary active component includes oxides of at least one of rubidium, cerium, niobium, chromium, tungsten, silver, cobalt, gallium, indium, antimony, bismuth, zirconium and erbium.

[0011] Among them, the specific surface area of ​​micron-sized titanium oxide is 10m². 2 / g-30m 2 / g, the specific surface area of ​​nano-titanium oxide is 50m². 2 / g-100m 2 / g.

[0012] A third aspect of the present invention provides a catalyst prepared by the method described in the second aspect.

[0013] 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.

[0014] At least one section of the catalyst bed is filled with the catalyst described in the first or third aspect.

[0015] 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 in the first or third aspect;

[0016] Alternatively, the method may include: preparing a catalyst according to the method described in the second aspect, and then contacting mesitylene with an oxygen-containing gas in the presence of the catalyst;

[0017] Alternatively, the method includes introducing mesitylene into the reactor described in the fourth aspect to contact it with oxygen-containing gas.

[0018] The catalyst containing micron-sized and nano-sized titanium dioxide of this invention can be rapidly activated, increasing the concentration of mesitylene to 58 g / Nm³ within 2 hours. 3 In addition, this can also improve the yield of homogenate.

[0019] By employing a preferred embodiment of the present invention, the catalyst containing micron-sized and nano-sized titanium oxide of the present invention is loaded into the inlet section, which can improve the overall utilization rate of the catalyst bed and make the average anhydride weight yield higher than 101%. Detailed Implementation

[0020] 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.

[0021] The first aspect of the present invention provides a catalyst for preparing homohydric anhydride, the catalyst comprising a support and an active component supported on the support, wherein the active component comprises a main active component and an auxiliary active component, the main active component comprising vanadium oxide, cesium oxide, micron-sized titanium oxide and nano-sized titanium oxide, and the auxiliary active component comprising an oxide of at least one of rubidium, cerium, niobium, chromium, tungsten, silver, cobalt, gallium, indium, antimony, bismuth, zirconium and erbium.

[0022] Among them, the specific surface area of ​​micron-sized titanium oxide is 10m². 2 / g-30m 2 / g, the specific surface area of ​​nano-titanium oxide is 50m². 2 / g-100m 2 / g.

[0023] According to the present invention, preferably, the particle size of the micron-sized titanium oxide is 0.1-1 micron.

[0024] According to the present invention, preferably, the particle size of nano-titanium oxide is 10-50 nm.

[0025] According to the present invention, preferably, the carrier material is selected from at least one of talc, silicon carbide, aluminum silicate, quartz and ceramics.

[0026] According to the present invention, preferably, the content of the active component is 200-400g relative to 2000g of carrier.

[0027] According to the present invention, preferably, the weight ratio of the main active component to the auxiliary active component is 100:1.5-5.7, more preferably 1.7-2.

[0028] According to the present invention, preferably, the carrier is selected from at least one of talc, silicon carbide, aluminum silicate, quartz and ceramics.

[0029] According to the present invention, preferably, the specific surface area of ​​the micron-sized titanium oxide is 15m². 2 / g-25m 2 / g, the specific surface area of ​​nano-titanium oxide is 55m². 2 / g-70m 2 / g.

[0030] According to the present invention, preferably, the weight ratio of vanadium oxide (calculated as V2O5), cesium oxide (calculated as Cs), micron-sized titanium oxide (calculated as TiO2), and nano-sized titanium oxide (calculated as TiO2) is 100:3-6:1300-1800:14-19.

[0031] According to the present invention, preferably, the weight ratio of micron-sized titanium oxide (based on TiO2) to nano-sized titanium oxide (based on TiO2) is 10-95:1, more preferably 18-95:1, and even more preferably 20-30:1.

[0032] According to the present invention, preferably, the auxiliary active components include niobium oxide and antimony oxide. More preferably, the weight ratio of niobium oxide (calculated as Nb₂O₅) to antimony oxide (calculated as Sb₂O₃) is 1:9-19, preferably 9.1-10.

[0033] The second aspect of the present invention provides a method for preparing a homogeneous anhydride catalyst, the method comprising: loading a main active component and an auxiliary active component onto a support, wherein the main active component includes oxides of vanadium, oxides of cesium, micron-sized titanium dioxide and nano-sized titanium dioxide, and the auxiliary active component includes oxides of at least one of rubidium, cerium, niobium, chromium, tungsten, silver, cobalt, gallium, indium, antimony, bismuth, zirconium and erbium.

[0034] Among them, the specific surface area of ​​micron-sized titanium oxide is 10m². 2 / g-30m 2 / g, the specific surface area of ​​nano-titanium oxide is 50m². 2 / g-100m 2 / g.

[0035] According to the present invention, preferably, the specific surface area of ​​the micron-sized titanium oxide is 15m². 2 / g-25m 2 / g, the specific surface area of ​​nano-titanium oxide is 55m². 2 / g-70m 2 / g.

[0036] According to the present invention, preferably, the particle size of the micron-sized titanium oxide is 0.1-1 micron.

[0037] According to the present invention, preferably, the particle size of nano-titanium oxide is 10-50 nm.

[0038] According to the present invention, preferably, the carrier material is selected from at least one of talc, silicon carbide, aluminum silicate, quartz and ceramics.

[0039] According to the present invention, preferably, the amounts of the main active component and the auxiliary active component are such that, relative to 2000g of the support, the content of the active component in the obtained catalyst is 200-400g relative to 2000g of the support.

[0040] According to the present invention, preferably, the amount of the main active component and the auxiliary active component is such that the weight ratio of the main active component and the auxiliary active component in the obtained catalyst is 100:1.5-5.7, preferably 1.7-2.

[0041] According to the present invention, preferably, the carrier is selected from at least one of talc, silicon carbide, aluminum silicate, quartz and ceramics.

[0042] According to the present invention, preferably, the amounts of the main active component and the auxiliary active component are such that the weight ratio of vanadium oxide (calculated as V2O5), cesium oxide (calculated as Cs), micronized titanium oxide (calculated as TiO2), and nano-titanium oxide (calculated as TiO2) in the obtained catalyst is 100:3-6:1300-1800:14-19.

[0043] According to the present invention, preferably, the amount of micron-sized titanium oxide and nano-sized titanium oxide is such that the weight ratio of micron-sized titanium oxide (calculated as TiO2) to nano-sized titanium oxide (calculated as TiO2) in the obtained catalyst is 85-95:1, preferably 88-91:1.

[0044] According to the present invention, preferably, the auxiliary active component includes niobium oxide and antimony oxide. More preferably, the amount of auxiliary active component is such that the weight ratio of niobium oxide (calculated as Nb₂O₅) to antimony oxide (calculated as Sb₂O₃) in the obtained catalyst is 10-95:1, more preferably 18-95:1, and even more preferably 20-30:1.

[0045] According to the present invention, preferably, the main active component and auxiliary active component are loaded onto the support by: mixing a solution containing vanadium precursor and cesium precursor with a solution containing micron-sized titanium oxide, nano-sized titanium oxide and auxiliary active component precursor to obtain an active component slurry, coating the active component slurry onto the support, and then activating it.

[0046] According to the present invention, preferably, the solution containing the vanadium precursor, the phosphorus precursor and the cesium precursor further contains a reducing agent and a solvent. The reducing agent may be oxalic acid.

[0047] According to the present invention, preferably, the mass ratio of solvent to reducing agent is 100:15-25; more preferably, it is 100:18-24.

[0048] 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 may be 0.1-1:1, preferably 0.1-0.7:1.

[0049] According to the present invention, preferably, the vanadium precursor is ammonium metavanadate and / or vanadium pentoxide.

[0050] According to the present invention, preferably, the cesium precursor is selected from at least one of cesium nitrate, cesium sulfate and cesium chloride.

[0051] According to the present invention, preferably, the active component slurry further contains a binder, which is an emulsion of at least one selected from vinyl acetate-acrylate copolymer, vinyl acetate-ethylene copolymer, vinyl acetate-cis-butenedioic acid copolymer, and acrylic acid-maleic acid copolymer.

[0052] According to the present invention, preferably, the viscosity of the active component slurry is 10 Pa·s-40 Pa·s, more preferably 12 Pa·s-25 Pa·s.

[0053] According to the present invention, preferably, the activation conditions include activation in an oxidizing atmosphere for 4-24 hours.

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

[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.

[0056] At least one section of the catalyst bed is filled with the catalyst described in the first or third aspect.

[0057] According to the present invention, preferably, the catalyst bed of the catalyst described in the first or third aspect accounts for 30-70% of the total length of the catalyst bed.

[0058] According to the present invention, preferably, the reactor comprises two catalyst beds, wherein the catalyst packed in the second catalyst bed does not contain nano-titanium oxide.

[0059] According to the present invention, preferably, the length ratio of the first catalyst bed to the second catalyst bed is 0.5-0.9:1, more preferably 0.63-0.83:1.

[0060] According to the present invention, preferably, the active components of the catalyst packed in the second catalyst bed include a main active component and an auxiliary active component. The main active component includes oxides of vanadium, oxides of phosphorus, oxides of cesium, and micron-sized titanium dioxide. The auxiliary active component includes oxides of at least one of rubidium, cerium, niobium, chromium, tungsten, silver, cobalt, gallium, indium, antimony, bismuth, zirconium, and erbium.

[0061] According to the present invention, preferably, the weight ratio of vanadium oxide (calculated as V2O5), phosphorus oxide (calculated as P), cesium oxide (calculated as Cs), and micron-sized titanium oxide (calculated as TiO2) in the active components of the catalyst packed in the second catalyst bed is 100:1.9-2.3:3-3.4:1300-1400.

[0062] According to the present invention, preferably, the weight ratio of the main active component to the auxiliary active component in the active component of the catalyst packed in the second catalyst bed is 100:2-3, more preferably 100:2.6-2.9.

[0063] According to the present invention, preferably, the auxiliary active component of the catalyst packed in the second catalyst bed includes an oxide of at least one of niobium, antimony and zirconium, and the weight ratio of niobium oxide (calculated as Nb2O5), zirconium oxide (calculated as ZrO2), and antimony oxide (calculated as Sb2O3) is 1:1.5-2:15-20.

[0064] In this invention, the catalyst packed in the second catalyst bed can be prepared according to methods commonly used in the art, as long as the obtained catalyst can meet the above-mentioned content of active components.

[0065] 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 in the first or third aspect;

[0066] Alternatively, the method may include: preparing a catalyst according to the method described in the second aspect, and then contacting mesitylene with an oxygen-containing gas in the presence of the catalyst;

[0067] Alternatively, the method includes introducing mesitylene into the reactor described in the fourth aspect to contact it with oxygen-containing gas.

[0068] According to the present invention, preferably, the oxygen-containing gas is air.

[0069] According to the present invention, preferably, the contact conditions include: a temperature of 340-360°C; and an air volume hourly velocity of 1500-5000 h⁻¹. -1 Preferably 2500-4500h -1 The concentration of mesitylene is 50-60 g / m³. 3 In this invention, the pressure of the reaction can be negative pressure, normal pressure, or pressurized pressure, preferably normal pressure.

[0070] 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.

[0071] This invention uses a fixed-bed reactor and employs molten salt circulation for heat exchange; the contact temperature refers to the temperature of the molten salt. During 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.

[0072] The present invention will be described in detail below through embodiments. In the following embodiments,

[0073] The carrier is a talc ring.

[0074] The composition of the catalyst is calculated based on the amount of feed.

[0075] The catalytic products were analyzed using chromatographic methods.

[0076] The yield of homogeneous anhydride = weight of homogeneous anhydride of the product ÷ weight of homotetramethylbenzene in the reaction × 100%.

[0077] Example 1

[0078] Preparation of catalyst A:

[0079] (1) Prepare a solution by adding 53.34g ammonium metavanadate, 124.35g oxalic acid, cesium sulfate, 220ml formamide, and 350g water. The mass ratio of formamide to water is 0.7:1.

[0080] (2) The solution was mixed with micron-sized titanium dioxide (particle size 0.2 μm, specific surface area 22 m²). 2 / g), niobium oxalate, antimony trioxide, nano titanium dioxide (particle size 0.01μm, specific surface area 65m²). 2 Pour 70g of vinyl acetate / ethylene copolymer emulsion into a ball mill and add 70g of vinyl acetate / ethylene copolymer emulsion. Ball mill for 4 hours to emulsify the active component precursor into a uniform suspension emulsion, and control the emulsion viscosity to 12 Pa·s.

[0081] (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 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 ring. When the carrier temperature reached 130℃, the feed nozzle was turned on and the hot air temperature was controlled at 100℃. The liquid spraying rate was 30ml / min. The catalytic active material emulsion was sprayed onto the surface of the carrier magnetic ring through the nozzle and dried rapidly by hot air. The content of the catalytic active material reached 13.5% by weight of the carrier to prepare catalyst precursor A. Catalyst precursor A was activated in an oxidizing atmosphere for 6h to obtain the catalyst.

[0082] In the catalyst, the weight ratio of the main active component to the auxiliary active component is 100:1.94.

[0083] In the catalyst, the weight ratio of vanadium oxide (calculated as V2O5), cesium oxide (calculated as Cs), niobium oxide (calculated as Nb2O5), antimony oxide (calculated as Sb2O3), micron-sized titanium dioxide (calculated as TiO2), and nano-sized titanium dioxide (calculated as TiO2) is 100:5.46:2.92:28.65:1502.42:16.88.

[0084] Preparation of catalyst B:

[0085] (1) Dissolve 58.65g ammonium metavanadate, 137.92g oxalic acid, cesium sulfate, ammonium dihydrogen phosphate, and 220ml formamide in 350g water to make a solution. The mass ratio of formamide to water is 0.7:1.

[0086] (2) The solution was mixed with micron-sized titanium dioxide (particle size 0.2 μm, specific surface area 23 m²). 2 Antimony trioxide, niobium oxalate, and zirconium sulfate were added to a ball mill, along with 100g of vinyl acetate / ethylene copolymer emulsion. The mixture was ball-milled for 4 hours to emulsify the active component precursor into a uniform suspension emulsion, with the emulsion viscosity controlled at 12 Pa·s.

[0087] (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 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 ring. When the carrier temperature reached 110℃, the feed nozzle was turned on and the hot air temperature was controlled at 110℃. The liquid spraying rate was 60ml / min. The catalytic active material emulsion was sprayed onto the surface of the carrier magnetic ring through the nozzle and dried rapidly by hot air. The content of the catalytic active material reached 16.7% by weight of the carrier. After spraying, catalyst precursor B was prepared. Catalyst precursor B was activated in an oxidizing atmosphere for 5h to obtain the catalyst.

[0088] In the catalyst, the weight ratio of the main active component to the auxiliary active component is 100:2.83.

[0089] In the catalyst, the weight ratio of vanadium oxide (calculated as V2O5), phosphorus oxide (calculated as P), cesium oxide (calculated as Cs), niobium oxide (calculated as Nb2O5), zirconium oxide (calculated as ZrO2), antimony oxide (calculated as Sb2O3), and micron-sized titanium oxide (calculated as TiO2) is 100:2.29:3.3:1.94:3.33:36.8:1381.75.

[0090] Example 2

[0091] Preparation of catalyst A:

[0092] Catalyst A was prepared according to the preparation method of catalyst A in Example 1, except that the weight ratio of micron-sized titanium dioxide to nano-sized titanium dioxide was 20 while keeping the total weight of micron-sized titanium dioxide and nano-sized titanium dioxide constant.

[0093] The preparation method of catalyst B is the same as that of catalyst B in Example 1.

[0094] Example 3

[0095] Preparation of catalyst A:

[0096] (1) Dissolve 49.88g ammonium metavanadate, 112.35g oxalic acid, cesium sulfate, 220ml formamide in 350g water to make a solution. The mass ratio of formamide to water is 0.7:1.

[0097] (2) The solution was mixed with micron-sized titanium dioxide (particle size 0.2 μm, specific surface area 22 m²). 2 / g), niobium oxalate, antimony trioxide, nano titanium dioxide (particle size 0.01μm, specific surface area 65m²). 2 Pour 70g of vinyl acetate / ethylene copolymer emulsion into a ball mill and add 70g of vinyl acetate / ethylene copolymer emulsion. Ball mill for 4 hours to emulsify the active component precursor into a uniform suspension emulsion, and control the emulsion viscosity to 12 Pa·s.

[0098] (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 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 ring. When the carrier temperature reached 130℃, the feed nozzle was turned on and the hot air temperature was controlled at 100℃. The liquid spraying rate was 30ml / min. The catalytic active material emulsion was sprayed onto the surface of the carrier magnetic ring through the nozzle and dried rapidly by hot air. The content of the catalytic active material reached 13.8% by weight of the carrier to prepare catalyst precursor A. Catalyst precursor A was activated in an oxidizing atmosphere for 5h to obtain the catalyst.

[0099] In the catalyst, the weight ratio of the main active component to the auxiliary active component is 100:1.79.

[0100] In the catalyst, the weight ratio of vanadium oxide (calculated as V2O5), cesium oxide (calculated as Cs), niobium oxide (calculated as Nb2O5), antimony oxide (calculated as Sb2O3), micron-sized titanium dioxide (calculated as TiO2), and nano-sized titanium dioxide (calculated as TiO2) is 100:5.72:3.1:28.26:1624.69:18.05.

[0101] Preparation of catalyst B:

[0102] (1) Dissolve 60.35g ammonium metavanadate, 142.32g oxalic acid, cesium sulfate, ammonium dihydrogen phosphate, and 220ml formamide in 350g water to make a solution. The mass ratio of formamide to water is 0.7:1.

[0103] (2) The solution was mixed with micron-sized titanium dioxide (particle size 0.2 μm, specific surface area 23 m²). 2 Antimony trioxide, niobium oxalate, and zirconium sulfate were added to a ball mill, along with 100g of vinyl acetate / ethylene copolymer emulsion. The mixture was ball-milled for 4 hours to emulsify the active component precursor into a uniform suspension emulsion, with the emulsion viscosity controlled at 12 Pa·s.

[0104] (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 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 ring. When the carrier temperature reached 110℃, the feed nozzle was turned on and the hot air temperature was controlled at 110℃. The liquid spraying rate was 60ml / min. The catalytic active material emulsion was sprayed onto the surface of the carrier magnetic ring through the nozzle and dried rapidly by hot air. The content of the catalytic active material reached 16.8% by weight of the carrier. The spraying was completed, and catalyst precursor B was prepared. Catalyst precursor B was activated in an oxidizing atmosphere for 5h to obtain the catalyst.

[0105] In the catalyst, the weight ratio of the main active component to the auxiliary active component is 100:2.66.

[0106] In the catalyst, the weight ratio of vanadium oxide (calculated as V2O5), phosphorus oxide (calculated as P), cesium oxide (calculated as Cs), niobium oxide (calculated as Nb2O5), zirconium oxide (calculated as ZrO2), antimony oxide (calculated as Sb2O3), and micron-sized titanium oxide (calculated as TiO2) is 100:1.98:3.12:1.96:3.58:32.95:1342.83.

[0107] Example 4

[0108] Catalyst A was prepared according to the preparation method of catalyst A in Example 3, except that the weight ratio of micron-sized titanium dioxide to nano-sized titanium dioxide was 20 while keeping the total weight of micron-sized titanium dioxide and nano-sized titanium dioxide constant.

[0109] Catalyst B was prepared in the same way as catalyst B in Example 3.

[0110] Example 5

[0111] Preparation of catalyst A:

[0112] The catalyst was prepared according to the preparation method of catalyst A in Example 1, except that the weight ratio of micronized titanium dioxide to nano-titanium dioxide was 14.75 while keeping the total weight of micronized titanium dioxide and nano-titanium dioxide constant.

[0113] The preparation method of catalyst B is the same as that of catalyst B in Example 1.

[0114] Comparative Example 1

[0115] Preparation of catalyst A:

[0116] The catalyst was prepared according to the preparation method of catalyst A in Example 1, except that the nano titanium dioxide was replaced with an equal mass of micron-sized titanium oxide.

[0117] The preparation method of catalyst B is the same as that of catalyst B in Example 1.

[0118] Comparative Example 2

[0119] Preparation of catalyst A:

[0120] The catalyst was prepared according to the preparation method of catalyst A in Example 3, except that the nano titanium dioxide was replaced with an equal mass of micron-sized titanium oxide.

[0121] Catalyst B was prepared in the same way as catalyst B in Example 3.

[0122] Comparative Example 3

[0123] The catalyst was prepared according to the method in Example 1, except that the particle size of the nano-titanium dioxide was 0.005 μm and the specific surface area was 120 m². 2 / g.

[0124] Test Example 1

[0125] The performance of the catalysts prepared in the above examples and comparative examples 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, and a multi-point temperature measurement system was installed inside the tube. The homogenized anhydride catalyst was loaded in two stages, with catalyst B and catalyst A loaded from bottom to top. Catalyst B was loaded to a height of 1700 mm, and catalyst A to a height of 1400 mm, for a total loading height of 3100 mm. The material entered the reactor from the top to contact the catalyst. After feeding, the hot spot temperature was controlled at 420-430℃, and the air space velocity was 4000 h⁻¹. -1 The concentration of mesitylene was gradually increased to the concentration shown in Table 1. After the reaction stabilized for 2 hours, samples were taken at the reactor outlet for analysis to calculate the yield of the homogeneous anhydride and to evaluate the performance of the catalyst under the highest load. The results are shown in Table 1.

[0126] Table 1

[0127]

[0128]

[0129] As can be seen from the results in Table 1, Examples 1-4 using the addition of nano-titanium dioxide in this invention have a significantly improved anhydride yield.

[0130] Test Example 2

[0131] The test was conducted according to the method of Test Example 1, except that catalyst A and catalyst B prepared in Example 1 were loaded from bottom to top. The loading height of catalyst A was 1700 mm, and the loading height of catalyst B was 1400 mm. The total loading height was 3100 mm. Results: The molten salt temperature was 340℃, and the mesitylene concentration was 26 g / m³. 3 The anhydride yield was 55 wt%.

[0132] By comparing Test Example 1 and Test Example 2, it can be seen that when the catalyst is loaded in the manner of Test Example 1 (i.e., first contacted with catalyst A and then with catalyst B), not only can the yield of homogenous anhydride be increased, but also the concentration of tetramethylbenzene can be increased. In other words, when the catalyst is loaded in the manner of Test Example 1, the yield of homogenous anhydride can be increased while increasing the reaction load.

[0133] 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 for the preparation of phthalic anhydride, characterized in that The catalyst comprises a carrier and active components supported on the carrier, wherein the active components comprise primary active components and auxiliary active components, the primary active components comprise oxides of vanadium, oxides of cesium, micron titanium oxide and nano titanium oxide, and the auxiliary active components comprise oxides of at least one of rubidium, cerium, niobium, chromium, tungsten, silver, cobalt, gallium, indium, antimony, bismuth, zirconium and erbium elements; The specific surface area of the micron titanium oxide is 10 m 2 / g-30 m 2 The specific surface area of the nanometer titanium oxide is 50 m 2 / g-100 m 2 / g. The particle size of the micron titanium oxide is 0.1-1 microns; and the particle size of the nano titanium oxide is 10-50 nm.

2. The catalyst of claim 1, wherein, The content of the active components is 200-400 g relative to 2000 g of the carrier; And / or, the weight ratio of the primary active components to the auxiliary active components is 100:1.5-5.7; And / or, the carrier is selected from at least one of talc, silicon carbide, aluminum silicate, quartz and ceramic; And / or, the weight ratio of the oxides of vanadium calculated based on V2O5, the oxides of cesium calculated based on Cs, the micron titanium oxide calculated based on TiO2 and the nano titanium oxide calculated based on TiO2 is 100:3-6:1300-1800:14-19; And / or, the weight ratio of the micron titanium oxide calculated based on TiO2 to the nano titanium oxide calculated based on TiO2 is 10-95:

1.

3. The catalyst of claim 2, wherein, The weight ratio of the primary active components to the auxiliary active components is 100:1.7-2; And / or, the weight ratio of the micron titanium oxide calculated based on TiO2 to the nano titanium oxide calculated based on TiO2 is 18-95:

1.

4. The catalyst of claim 2, wherein, The weight ratio of the micron titanium oxide calculated based on TiO2 to the nano titanium oxide calculated based on TiO2 is 20-30:

1.

5. A process for the preparation of a catalyst for the production of phthalic anhydride, characterized in that, The method comprises: supporting the primary active components and the auxiliary active components on the carrier, the primary active components comprise oxides of vanadium, oxides of cesium, micron titanium oxide and nano titanium oxide, and the auxiliary active components comprise oxides of at least one of rubidium, cerium, niobium, chromium, tungsten, silver, cobalt, gallium, indium, antimony, bismuth, zirconium and erbium elements; The specific surface area of the micron titanium oxide is 10 m 2 / g-30 m 2 The specific surface area of the nanometer titanium oxide is 50 m 2 / g-100 m 2 / g; The particle size of the micron titanium oxide is 0.1-1 microns; and the particle size of the nano titanium oxide is 10-50 nm.

6. The method of claim 5, wherein, The content of the active components is 200-400 g relative to 2000 g of the carrier; And / or, the weight ratio of the primary active components to the auxiliary active components is 100:1.5-5.7; And / or, the carrier is selected from at least one of talc, silicon carbide, aluminum silicate, quartz and ceramic; And / or, the weight ratio of the oxides of vanadium calculated based on V2O5, the oxides of cesium calculated based on Cs, the micron titanium oxide calculated based on TiO2 and the nano titanium oxide calculated based on TiO2 is 100:3-6:1300-1800:14-19; And / or, the weight ratio of the micron titanium oxide calculated based on TiO2 to the nano titanium oxide calculated based on TiO2 is 10-95:

1.

7. The method of claim 6, wherein, The weight ratio of the primary active components to the auxiliary active components is 100:1.7-2; And / or, the amounts of the micro-titanium oxide and the nano-titanium oxide are such that the weight ratio of the micro-titanium oxide calculated as TiO2 to the nano-titanium oxide calculated as TiO2 in the resulting catalyst is 18-95:

1.

8. The method of claim 6, wherein, The amounts of the micro-titanium oxide and the nano-titanium oxide are such that the weight ratio of the micro-titanium oxide calculated as TiO2 to the nano-titanium oxide calculated as TiO2 in the resulting catalyst is 20-30:

1.

9. The method of claim 6, wherein, The manner of loading the primary active component and the auxiliary active component on the carrier includes: mixing a solution containing the vanadium precursor and the cesium precursor with a solution containing the micro-titanium oxide, the nano-titanium oxide and the auxiliary active component precursor to obtain an active component slurry, then coating the active component slurry on the carrier, and then activating.

10. The catalyst prepared by the method of any one of claims 5-9.

11. A reactor packed with a catalyst, characterized in that, The reactor is filled with at least one catalyst bed layer, The at least one catalyst bed layer is filled with the catalyst of any one of claims 1-4 and 10.

12. The reactor of claim 11, wherein, The ratio of the length of the catalyst bed layer filled with the catalyst of any one of claims 1-4 and 10 to the total length of the catalyst bed layers is 30-70%.

13. The reactor according to claim 11 or 12, wherein, The reactor includes two catalyst bed layers, the first catalyst bed layer is filled with the catalyst of any one of claims 1-4 and 10, and the second catalyst bed layer is filled with a catalyst not containing nano-titanium oxide.

14. The reactor of claim 13, wherein, The length ratio of the first catalyst bed layer to the second catalyst bed layer is 0.5-0.9:1; And / or, the active component of the catalyst filled in the second catalyst bed layer includes a primary active component and an auxiliary active component, the primary active component includes oxides of vanadium, phosphorus, cesium and micro-titanium oxide, and the auxiliary active component includes oxides of at least one of rubidium, cerium, niobium, chromium, tungsten, silver, cobalt, gallium, indium, antimony, bismuth, zirconium and erbium.

15. A process for the production of phthalic anhydride, characterized by, The method includes: contacting durene with an oxygen-containing gas in the presence of the catalyst of any one of claims 1-4 and 10; Or, the method includes: preparing the catalyst according to the method of any one of claims 5-9, and then contacting durene with an oxygen-containing gas in the presence of the catalyst; Or, the method includes: feeding durene and an oxygen-containing gas into the reactor of any one of claims 11-14.

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