Catalysts with naphthalene oxide function, their preparation methods and applications

Abstract

This invention relates to the field of catalytic oxidation of naphthalene to phthalic anhydride, and discloses a catalyst with naphthalene oxidation function, its preparation method, and its application. The catalyst comprises a support and an inner active component and an outer active component supported on the support. The active components in the inner and outer active components have different compositions, and each independently includes a main active component and auxiliary active components. The main active components of both the inner and outer active components independently include vanadium oxides, and the weight ratio of vanadium oxides (based on V₂O₅) in the inner and outer active components is 1:0.65-1.1. The catalyst of this invention is a double-layer coated catalyst, with each layer containing a different effective component, which enhances the radial distribution of the reaction on the catalyst, thus improving the overall utilization efficiency of the catalyst and increasing the product yield.

Description

Technical Field

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

[0002] Phthalic anhydride (PA), or simply phthalic anhydride, is the main market application area for o-xylene (OX), and among the four major organic acid anhydrides, it has the largest production and consumption. Phthalic anhydride has three main uses: first, in the preparation of phthalate plasticizers (accounting for half of its global production capacity, the main variety being dioctyl phthalate (DOP), used as a plasticizer for polyvinyl chloride (PVC) resin); second, in the manufacture of unsaturated polyesters, used as glass-reinforced thermosetting engineering plastics; and third, in the manufacture of alkyd resins, used as surface coatings. With the development of the petrochemical industry, its demand is increasing daily. However, due to the persistently high price of o-xylene used to produce phthalic anhydride, the price of phthalic anhydride has fallen below the price of raw materials, affecting business operations. In recent years, the price of industrial naphthalene has declined, leading some phthalic anhydride plants to reconsider using the naphthalene process to produce phthalic anhydride in order to reduce costs and increase competitiveness. Therefore, the new naphthalene process and corresponding catalysts are now favored by the market.

[0003] Currently, patents for the oxidation of naphthalene to phthalic anhydride mainly focus on the optimization of auxiliaries and formulations. BASF has developed a novel catalyst for the mixed oxidation of o-xylene and naphthalene to phthalic anhydride. The active components of this catalyst are vanadium oxide and titanium dioxide, and it can contain mixed oxides of cesium compounds, phosphorus compounds, antimony oxide, and specific metals (such as lithium, potassium, rubidium, etc.). The catalyst is prepared by coating an inert porous support, and then layering the catalyst in a reactor, ensuring that catalyst layer A has the highest alkali metal content. In the flow direction, catalyst layers B, C, etc., located after catalyst layer A, have alkali metal contents ranging from 0% to 90% of those in catalyst layer A, and the alkali metal content of each catalyst layer is higher than that of the next catalyst layer in the flow direction.

[0004] Klein has developed a multilayer catalyst for the preparation of phthalic anhydride, which employs a catalyst arrangement having a first catalyst layer on the gas inlet side and at least one second catalyst layer with different catalytic activity downstream of the first catalyst layer along the gas flow direction. Summary of the Invention

[0005] To address the problem that catalyst coatings in existing technologies cannot be effectively utilized, this invention provides a catalyst with naphthalene oxide function, its preparation method, and its application.

[0006] To achieve the above objectives, the first aspect of the present invention provides a catalyst with naphthalene oxidation function, the catalyst comprising a support and an inner active component and an outer active component supported on the support, wherein the active components in the inner active component and the outer active component have different compositions, and the inner active component and the outer active component each independently include a main active component and an auxiliary active component.

[0007] The main active components of the inner and outer active components each independently include vanadium oxides, and the weight ratio of vanadium oxides (calculated as V2O5) in the inner and outer active components is 1:0.65-1.1.

[0008] A second aspect of the present invention provides a method for preparing a catalyst with naphthalene oxide function, the method comprising the following steps:

[0009] (1) Coating a mixture containing an inner layer active component precursor onto a carrier;

[0010] (2) Coat the product of step (1) with a mixture containing the precursor of the outer active component;

[0011] (3) Activate the product from step (2);

[0012] The inner layer active component precursor and the outer layer active component precursor each independently include the main active component precursor and the auxiliary active component precursor.

[0013] The main active component precursors of the inner layer active component precursor and the outer layer active component precursor each independently include vanadium oxide precursor, and the amount of vanadium oxide precursor is such that the weight ratio of vanadium oxide in the inner layer active component and the outer layer active component, calculated as V2O5, in the obtained catalyst is 1:0.65-1.1.

[0014] A third aspect of the present invention provides a catalyst prepared by the method described in the second aspect.

[0015] A fourth aspect of the present invention provides a method for producing phthalic anhydride, characterized in that the method comprises: contacting naphthalene 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 naphthalene with an oxygen-containing gas in the presence of the catalyst.

[0017] The naphthalene oxide catalyst provided by this invention is a double-coated catalyst, with each layer containing a different active ingredient. This enhances the radial distribution of the reaction on the catalyst, which is beneficial to improving the overall utilization efficiency of the catalyst and increasing the product yield. Detailed Implementation

[0018] 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.

[0019] The first aspect of the present invention provides a catalyst with naphthalene oxidation function, the catalyst comprising a support and an inner active component and an outer active component supported on the support, wherein the active components in the inner active component and the outer active component have different compositions, and the inner active component and the outer active component each independently include a main active component and an auxiliary active component.

[0020] The main active components of the inner and outer active components each independently include vanadium oxides, and the weight ratio of vanadium oxides (calculated as V2O5) in the inner and outer active components is 1:0.65-1.1, more preferably 1:0.68-0.95, and even more preferably 1:0.75-0.9.

[0021] According to the present invention, preferably, the carrier is selected from at least one of talc, silicon carbide, aluminum silicate, quartz and ceramics.

[0022] According to the present invention, preferably, the main active components in the inner layer also include oxides of phosphorus, oxides of cesium, and oxides of titanium.

[0023] According to the present invention, preferably, in the inner active component, the weight ratio of vanadium oxide (calculated as V2O5), phosphorus oxide (calculated as P), cesium oxide (calculated as Cs), and titanium oxide (calculated as TiO2) is 100:2-3:4-5:1000-1400; more preferably, it is 100:2.15-2.18:4.5-4.9:1085-1370.

[0024] According to the present invention, preferably, the main active components in the outer active layer also include oxides of cesium and oxides of titanium.

[0025] According to the present invention, preferably, in the outer active component, the weight ratio of vanadium oxide (calculated as V2O5), cesium oxide (calculated as Cs), and titanium oxide (calculated as TiO2) is 100:8.5-10:1500-1600, more preferably 100:8.5-9.65:1505-1585.

[0026] According to the present invention, preferably, the content of the inner layer active component is 120-140g and the content of the outer layer active component is 135-155g relative to 2000g of carrier.

[0027] According to the present invention, preferably, the weight ratio of the inner active component to the outer active component is 1:1-1.2.

[0028] According to the present invention, preferably, the auxiliary active component in the inner active component includes an oxide of at least one of rubidium, cerium, niobium, chromium, tungsten, silver, cobalt, gallium, indium, antimony, bismuth, zirconium and erbium.

[0029] According to the present invention, preferably, in the inner active component, the weight ratio of vanadium oxide (calculated as V2O5) to auxiliary active component (calculated as metal element oxide) is 1:0.3-0.5, more preferably 1:0.35-0.45.

[0030] According to the present invention, preferably, the auxiliary active component in the inner active component includes an oxide of at least one of niobium, antimony, and zirconium. More preferably, the weight ratio of niobium oxide (calculated as Nb₂O₅), zirconium oxide (calculated as ZrO₂), and antimony oxide (calculated as Sb₂O₃) in the inner active component is 0.03-0.2:0.05-0.2:1, and even more preferably 0.04-0.1:0.08-0.11:1.

[0031] According to the present invention, preferably, the auxiliary active component in the outer active component includes an oxide of at least one of rubidium, cerium, niobium, chromium, tungsten, silver, cobalt, gallium, indium, antimony, bismuth, zirconium and erbium.

[0032] According to the present invention, preferably, in the outer active component, the weight ratio of vanadium oxide (calculated as V2O5) to auxiliary active component (calculated as metal element oxide) is 1:0.3-0.5, more preferably 1:0.31-0.42.

[0033] According to the present invention, preferably, the auxiliary active component in the outer active component includes an oxide of at least one of niobium and antimony. More preferably, the weight ratio of niobium oxide (calculated as Nb₂O₅) to antimony oxide (calculated as Sb₂O₃) in the outer active component is 0.1-0.2:1, more preferably 0.12-0.13:1.

[0034] A second aspect of the present invention provides a method for preparing a catalyst with naphthalene oxide function, the method comprising the following steps:

[0035] (1) Coating a mixture containing an inner layer active component precursor onto a carrier;

[0036] (2) Coat the product of step (1) with a mixture containing the precursor of the outer active component;

[0037] (3) Activate the product from step (2);

[0038] The inner layer active component precursor and the outer layer active component precursor each independently include the main active component precursor and the auxiliary active component precursor.

[0039] The main active component precursors of the inner layer active component precursor and the outer layer active component precursor each independently include vanadium oxide precursor, and the amount of vanadium oxide precursor is such that the weight ratio of vanadium oxide (calculated as V2O5) in the inner layer active component and the outer layer active component in the obtained catalyst is 1:0.65-1.1, preferably 1:0.75-0.95.

[0040] According to the present invention, preferably, the carrier is selected from at least one of talc, silicon carbide, aluminum silicate, quartz and ceramics.

[0041] According to the present invention, preferably, the vanadium oxide precursors in the inner active component precursor and the outer active component precursor are each independently ammonium metavanadate and / or vanadium pentoxide.

[0042] According to the present invention, preferably, the amounts of the inner layer active component precursor and the outer layer active component precursor are such that, relative to 2000g of support, the content of the inner layer active component in the obtained catalyst is 120-140g and the content of the outer layer active component is 135-155g.

[0043] According to the present invention, preferably, the amount of the inner active component precursor and the outer active component precursor is such that the weight ratio of the inner active component to the outer active component in the obtained catalyst is 1:1-1.2.

[0044] According to the present invention, preferably, the main active component precursor in the inner layer active component precursor also includes an oxide precursor of phosphorus, an oxide precursor of cesium, and an oxide precursor of titanium.

[0045] According to the present invention, preferably, in the precursor of the inner active component, the amounts of the phosphorus oxide precursor, the cesium oxide precursor, and the titanium oxide precursor are such that the weight ratio of vanadium oxide (calculated as V2O5), phosphorus oxide (calculated as P), cesium oxide (calculated as Cs), and titanium oxide (calculated as TiO2) in the resulting inner active component is 100:2-3:4-5:1000-1400; preferably 100:2.15-2.18:4.5-4.9:1085-1370.

[0046] According to the present invention, preferably, in the outer active component precursor, the main active component precursor also includes a cesium oxide precursor and a titanium oxide precursor.

[0047] According to the present invention, preferably, in the precursor of the outer active component, the amount of cesium oxide precursor and titanium oxide precursor is such that the weight ratio of vanadium oxide (calculated as V2O5), cesium oxide (calculated as Cs), and titanium oxide (calculated as TiO2) in the resulting outer active component is 100:8.5-10:1500-1600, more preferably 100:8.5-9.65:1505-1585.

[0048] According to the present invention, preferably, the phosphorus oxide precursor in the inner active component precursor is at least one of ammonium dihydrogen phosphate, triammonium phosphate, and phosphorus pentoxide.

[0049] According to the present invention, preferably, the cesium oxide precursor in the inner active component precursor and the outer active component precursor are each independently at least one of cesium nitrate, cesium sulfate and cesium chloride.

[0050] According to the present invention, preferably, the titanium oxide precursors in both the inner and outer active component precursors are independently titanium dioxide, more preferably anatase titanium dioxide. The specific surface area of ​​anatase titanium dioxide can be 10 m². 2 / g-30m 2 / g, preferably 15m 2 / g-25m 2 / g.

[0051] According to the present invention, preferably, in the inner active component precursor, the auxiliary active component precursor includes an oxide precursor of at least one of rubidium, cerium, niobium, chromium, tungsten, silver, cobalt, gallium, indium, antimony, bismuth, zirconium and erbium.

[0052] According to the present invention, preferably, in the inner layer active component precursor, the amount of auxiliary active component precursor is such that the weight ratio of vanadium oxide (calculated as V2O5) to auxiliary active component (calculated as metal element oxide) in the obtained inner layer active component is 1:0.3-0.5, preferably 1:0.35-0.45.

[0053] According to the present invention, preferably, in the inner layer active component precursor, the auxiliary active component precursor includes an oxide precursor of at least one of niobium, antimony, and zirconium. More preferably, in the inner layer active component precursor, the amounts of niobium precursor, antimony precursor, and zirconium precursor are such that the weight ratio of niobium oxide (calculated as Nb₂O₅), zirconium oxide (calculated as ZrO₂), and antimony oxide (calculated as Sb₂O₃) in the resulting inner layer active component is 0.03-0.2:0.05-0.2:1, more preferably 0.04-0.1:0.08-0.11:1.

[0054] According to the present invention, preferably, in the outer active component precursor, the auxiliary active component precursor includes an oxide precursor of at least one of rubidium, cerium, niobium, chromium, tungsten, silver, cobalt, gallium, indium, antimony, bismuth, zirconium and erbium.

[0055] According to the present invention, preferably, in the outer active component precursor, the amount of auxiliary active component precursor is such that the weight ratio of vanadium oxide (calculated as V2O5) to auxiliary active component (calculated as metal element oxide) in the obtained outer active component is 1:0.3-0.5, more preferably 1:0.31-0.42.

[0056] According to the present invention, preferably, in the outer active component precursor, the auxiliary active component precursor includes an oxide precursor of at least one of niobium and antimony. More preferably, in the outer active component precursor, the amount of niobium precursor and antimony precursor is such that the weight ratio of niobium oxide (calculated as Nb₂O₅) to antimony oxide (calculated as Sb₂O₃) in the resulting outer active component is 0.1-0.2:1, more preferably 0.12-0.13:1.

[0057] According to the present invention, mixture one containing an inner layer active component precursor and mixture two containing an outer layer active component precursor can be prepared according to conventional methods in the art, for example:

[0058] (a) A solution is prepared by mixing a reducing agent, a vanadium oxide precursor, an optional phosphorus oxide precursor, an optional cesium oxide precursor, and a solvent.

[0059] (b) The solution obtained in step (a) is mixed with a titanium oxide precursor, an auxiliary active component precursor and a binder to obtain a slurry (i.e., mixture one or mixture two).

[0060] According to the present invention, preferably, the reducing agent is oxalic acid.

[0061] According to the present invention, preferably, the mass ratio of solvent to reducing agent is 100:15-35; more preferably, it is 100:21-31.

[0062] 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, preferably 0.6-0.8:1.

[0063] According to the present invention, preferably, the adhesive is an emulsion of at least one selected from vinyl acetate / acrylate, vinyl acetate / ethylene, vinyl acetate / cis-butadiene ester, and acrylic acid / maleic acid copolymer.

[0064] According to the present invention, preferably, the amount of adhesive is such that the viscosity of mixture one and mixture two are each independently 10 Pa·s-40 Pa·s, preferably 12 Pa·s-25 Pa·s.

[0065] According to the present invention, preferably, during the coating process, the spraying speed of the slurry is 30-60 mL / min relative to each 2000 g of carrier.

[0066] A third aspect of the present invention provides a catalyst prepared by the method described in the second aspect.

[0067] A fourth aspect of the present invention provides a method for producing phthalic anhydride, characterized in that the method comprises: contacting naphthalene with an oxygen-containing gas in the presence of the catalyst described in the first or third aspect;

[0068] Alternatively, the method may include: preparing a catalyst according to the method described in the second aspect, and then contacting naphthalene with an oxygen-containing gas in the presence of the catalyst.

[0069] According to the present invention, preferably, the contact conditions include: a temperature of 340-360°C; and an oxygen gas volume hourly space velocity of 2000-5000 h⁻¹. -1 Preferably 3000-4000h -1 The concentration of naphthalene is 70-80 g / m³. 3 In this invention, the pressure of the reaction can be negative pressure, normal pressure, or pressurized pressure, preferably normal pressure.

[0070] According to the present invention, preferably, the oxygen-containing gas is air.

[0071] In this invention, the concentration of naphthalene refers to the number of grams of naphthalene contained in a unit volume of air. The higher the value, the higher the content of naphthalene in the air.

[0072] 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.

[0073] The present invention will be described in detail below through embodiments. In the following embodiments,

[0074] Weight gain refers to the loading of the main active component and auxiliary active components based on an inert carrier.

[0075] The carrier is a talc ring.

[0076] The titanium dioxide is anatase titanium dioxide with a specific surface area of ​​20 m². 2 / g.

[0077] The catalytic products were analyzed using chromatographic methods.

[0078] Phthalic anhydride yield = weight of phthalic anhydride product ÷ weight of naphthalene reacted × 100%.

[0079] Example 1

[0080] (1) Preparation of a mixture containing an inner layer active component precursor: 62.33 g ammonium metavanadate, 144.52 g oxalic acid, cesium sulfate, ammonium dihydrogen phosphate, 220 mL formamide, and 350 g water were added to prepare solution one. The mass ratio of formamide to water was 0.7:1. Solution one, along with titanium dioxide, niobium oxalate, zirconium sulfate, and antimony trioxide, was poured into a ball mill. 70 g of vinyl acetate / ethylene copolymer emulsion was added, and the mixture was ball-milled for 4 h to emulsify the active component precursor into a uniform suspension emulsion one. The emulsion viscosity was controlled at 12-20 Pa·s.

[0081] (2) Preparation of Mixture II containing the outer active component precursor: 53.84 g ammonium metavanadate, 128.95 g oxalic acid, cesium sulfate, 220 ml formamide, and 350 g water were added to prepare Solution II. The mass ratio of formamide to water was 0.7:1. Solution II, along with titanium dioxide, niobium oxalate, and antimony trioxide, were poured into a ball mill. 70 g of vinyl acetate / ethylene copolymer emulsion was added, and the mixture was ball-milled for 4 h to emulsify the active component precursor into a uniform suspension emulsion II. The emulsion viscosity was controlled at 12-20 Pa·s.

[0082] (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. Suspension emulsion one and suspension emulsion two were added to different mixing tanks 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℃. First, suspension emulsion one was sprayed onto the surface of the carrier magnetic ring through the nozzle at a spraying rate of 30ml / min and dried rapidly by hot air. The amount of suspension emulsion one sprayed increased the carrier weight by 6.5% by weight. Then, suspension emulsion two was sprayed onto the carrier magnetic ring through the nozzle at a spraying rate of 30ml / min and dried rapidly by hot air. The amount of suspension emulsion two sprayed increased the carrier weight by 7.6% by weight. After spraying, the catalyst precursor was obtained, and the total weight gain of the carrier was 14.1% by weight. The catalyst precursor was packed in a single-tube reactor and activated at 400°C for 4 hours in an oxidizing atmosphere to obtain the catalyst.

[0083] Based on the feed amount, the weight ratio of vanadium oxide (calculated as V2O5), cesium oxide (calculated as Cs), phosphorus oxide (calculated as P), titanium oxide (calculated as TiO2), niobium oxide (calculated as Nb2O5), zirconium oxide (calculated as ZrO2), and antimony oxide (calculated as Sb2O3) in the inner active component is 100:4.53:2.15:1368.77:1.87:3.06:34.36.

[0084] Based on the amount of feed, the weight ratio of vanadium oxide (calculated as V2O5), cesium oxide (calculated as Cs), titanium oxide (calculated as TiO2), niobium oxide (calculated as Nb2O5), and antimony oxide (calculated as Sb2O3) in the outer active component is 100:8.62:1584.61:3.51:27.36.

[0085] Example 2

[0086] (1) A mixture containing an inner layer active component precursor was prepared according to the method of Example 1.

[0087] (2) Preparation of Mixture II containing the outer active component precursor: 56.27 g ammonium metavanadate, 131.46 g oxalic acid, cesium sulfate, 220 ml formamide, and 350 g water were added to prepare Solution II. The mass ratio of formamide to water was 0.7:1. Solution II, along with titanium dioxide, niobium oxalate, and antimony trioxide, were poured into a ball mill. 70 g of vinyl acetate / ethylene copolymer emulsion was added, and the mixture was ball-milled for 4 h to emulsify the active component precursor into a uniform suspension emulsion II. The emulsion viscosity was controlled at 12-20 Pa·s.

[0088] (3) Coating was performed according to step (3) of Example 1, except that the amount of suspension emulsion sprayed first increased the weight of the carrier by 6.1% by weight. The amount of suspension emulsion sprayed second increased the weight of the carrier by 7% by weight. After spraying, the catalyst precursor was obtained, and the total weight gain of the carrier was 13.1% by weight. The catalyst precursor was packed in a single-tube reactor and activated at 400°C for 4 hours in an oxidizing atmosphere to obtain the catalyst.

[0089] Based on the amount of feed, the weight ratio of vanadium oxide (calculated as V2O5), cesium oxide (calculated as Cs), titanium oxide (calculated as TiO2), niobium oxide (calculated as Nb2O5), and antimony oxide (calculated as Sb2O3) in the outer active component is 100:9:1516.18:3.47:28.39.

[0090] Example 3

[0091] (1) Preparation of a mixture containing an inner layer active component precursor: 78.56 g ammonium metavanadate, 182.45 g oxalic acid, cesium sulfate, ammonium dihydrogen phosphate, 220 ml formamide, and 350 g water were added to prepare solution one. The mass ratio of formamide to water was 0.7:1. Solution one, along with titanium dioxide, niobium oxalate, zirconium sulfate, and antimony trioxide, was poured into a ball mill. 70 g of vinyl acetate / ethylene copolymer emulsion was added, and the mixture was ball-milled for 4 h to emulsify the active component precursor into a uniform suspension emulsion one. The emulsion viscosity was controlled at 12-20 Pa·s.

[0092] (2) A mixture containing an outer active component precursor was prepared according to the method of Example 1.

[0093] (3) Coating was performed according to step (3) of Example 1, except that the amount of suspension emulsion sprayed first increased the weight of the carrier by 6.8% by weight, and the amount of suspension emulsion sprayed second increased the weight of the carrier by 7.6% by weight. After spraying, the catalyst precursor was obtained, and the total weight gain of the carrier was 14.4% by weight. The catalyst precursor was packed in a single-tube reactor and activated at 400°C for 4 hours in an oxidizing atmosphere to obtain the catalyst.

[0094] Based on the feed amount, the weight ratio of vanadium oxide (calculated as V2O5), cesium oxide (calculated as Cs), phosphorus oxide (calculated as P), titanium oxide (calculated as TiO2), niobium oxide (calculated as Nb2O5), zirconium oxide (calculated as ZrO2), and antimony oxide (calculated as Sb2O3) in the inner active component is 100:4.58:2.18:1085.99:2.77:2.89:30.95.

[0095] Example 4

[0096] (1) A mixture containing an inner layer active component precursor was prepared according to the method of Example 3.

[0097] (2) A mixture containing an outer active component precursor was prepared according to the method of Example 2.

[0098] (3) Coating was performed according to step (3) of Example 1, except that the amount of suspension emulsion sprayed first increased the weight of the carrier by 7% by weight. The amount of suspension emulsion sprayed second increased the weight of the carrier by 7.3% by weight. After spraying, the catalyst precursor was obtained, and the total weight gain of the carrier was 14.3% by weight. The catalyst precursor was packed in a single-tube reactor and activated at 400°C for 4 hours in an oxidizing atmosphere to obtain the catalyst.

[0099] Example 5

[0100] The catalyst was prepared according to the method of Example 1, except that ammonium dihydrogen phosphate and zirconium sulfate from step (1) were added to step (2).

[0101] Comparative Example 1

[0102] (1) Preparation of suspension emulsion: Prepare suspension emulsion according to the method of preparing mixture one in Example 1.

[0103] (2) The coating was carried out according to the method of step (3) in Example 1, except that the amount of suspension emulsion sprayed increased the weight of the carrier by 13.5% by weight. The catalyst precursor was packed in a single-tube reactor and activated at 400°C for 4 hours in an oxidizing atmosphere to obtain the catalyst.

[0104] Comparative Example 2

[0105] (1) Preparation of suspension emulsion: Prepare suspension emulsion according to the method of preparing mixture one in Example 3.

[0106] (2) The coating was carried out according to the method of step (3) in Example 1, except that the amount of suspension emulsion sprayed increased the weight of the carrier by 14.3% by weight. The catalyst precursor was packed in a single-tube reactor and activated at 400°C for 4 hours in an oxidizing atmosphere to obtain the catalyst.

[0107] Comparative Example 3

[0108] (1) Preparation of suspension emulsion: Prepare suspension emulsion according to the method of preparing mixture two in Example 1.

[0109] (2) The coating was carried out according to the method of step (3) in Example 1, except that the amount of suspension emulsion sprayed increased the weight of the carrier by 14.6% by weight. The catalyst precursor was packed in a single-tube reactor and activated at 400°C for 4 hours in an oxidizing atmosphere to obtain the catalyst.

[0110] Comparative Example 4

[0111] (1) Preparation of suspension emulsion: Prepare suspension emulsion according to the method of preparing mixture two in Example 2.

[0112] (2) The coating was carried out according to the method of step (3) in Example 1, except that the amount of suspension emulsion sprayed increased the weight of the carrier by 14.3% by weight. The catalyst precursor was packed in a single-tube reactor and activated at 400°C for 4 hours in an oxidizing atmosphere to obtain the catalyst.

[0113] Comparative Example 5

[0114] The catalyst was prepared according to the method of Example 1, except that suspension emulsion II was sprayed onto the support first, and then suspension emulsion I was sprayed onto the support.

[0115] Test case

[0116] The catalyst performance was evaluated using a single-tube reactor simulating industrial production conditions. The reactor outlet was connected to an analysis system and a reactant collection system. The catalysts prepared in the above examples and comparative examples were loaded into the single-tube reactor, and then a mixture of naphthalene and air was introduced into the reactor at an air space velocity of 4000 h⁻¹. -1 The concentration of naphthalene in the mixed gas, the temperature of the molten salt, and the hot spot temperature are shown in Table 1. The concentration of naphthalene is 40 g / m³. 3 The concentration was gradually increased to the maximum concentration shown in Table 1. After reacting for 150 hours, samples were taken at the reactor outlet for analysis to assess the phthalic anhydride yield under the highest catalyst load.

[0117] Table 1

[0118]

[0119] As can be seen from the results in Table 1, the catalyst of the present invention can not only increase the yield of phthalic anhydride, but also increase the maximum concentration of naphthalene (i.e., increase the reaction load).

[0120] 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 naphthalene oxidation function, characterized in that, The catalyst comprises a support and an inner active component and an outer active component supported on the support. The active components in the inner and outer active components have different compositions. Each of the inner and outer active components independently includes a main active component and an auxiliary active component. The main active components of the inner and outer active components independently include vanadium oxides, and the weight ratio of vanadium oxides (based on V2O5) in the inner and outer active components is 1:0.65-1.

1. In the inner active components, the main active components also include oxides of phosphorus, oxides of cesium, and oxides of titanium, and the weight ratio of vanadium oxide (calculated as V2O5), phosphorus oxide (calculated as P), cesium oxide (calculated as Cs), and titanium oxide (calculated as TiO2) is 100:2-3:4-5:1000-1400; the weight ratio of vanadium oxide (calculated as V2O5) and auxiliary active components (calculated as oxides of metal elements) is 1:0.3-0.5; the auxiliary active components include oxides of niobium, antimony, and zirconium; In the outer active component, the main active components also include cesium oxide and titanium oxide, and the weight ratio of vanadium oxide (calculated as V2O5), cesium oxide (calculated as Cs), and titanium oxide (calculated as TiO2) is 100:8.5-10:1500-1600; the weight ratio of vanadium oxide (calculated as V2O5) and auxiliary active components (calculated as metal element oxides) is 1:0.3-0.5; the auxiliary active components include niobium and antimony oxides.

2. The catalyst according to claim 1, wherein, Compared to a 2000g carrier, the content of the inner active component is 120-140g, and the content of the outer active component is 135-155g. And / or, the weight ratio of the inner active component to the outer active component is 1:1-1.

2.

3. The catalyst according to claim 1, wherein, In the inner active component, the weight ratio of vanadium oxide (calculated as V2O5) to auxiliary active component (calculated as metal element oxide) is 1:0.35-0.

45. And / or, in the outer active component, the weight ratio of vanadium oxide (calculated as V2O5) to auxiliary active component (calculated as metal element oxide) is 1:0.31-0.

42.

4. The catalyst according to claim 1, wherein, In the inner active component, the weight ratio of niobium oxide (calculated as Nb2O5), zirconium oxide (calculated as ZrO2), and antimony oxide (calculated as Sb2O3) is 0.03-0.2:0.05-0.2:

1. In the outer active component, the weight ratio of niobium oxide (calculated as Nb2O5) to antimony oxide (calculated as Sb2O3) is 0.1-0.2:

1.

5. The catalyst according to claim 1, wherein, In the inner active component, the weight ratio of niobium oxide (calculated as Nb2O5), zirconium oxide (calculated as ZrO2), and antimony oxide (calculated as Sb2O3) is 0.04-0.1:0.08-0.11:

1.

6. The catalyst according to claim 1, wherein, In the outer active component, the weight ratio of niobium oxide (calculated as Nb2O5) to antimony oxide (calculated as Sb2O3) is 0.12-0.13:

1.

7. A method for preparing a catalyst with naphthalene oxide function, characterized in that, The method includes the following steps: (1) Coating a mixture containing an inner layer active component precursor onto a carrier; (2) Coat the product of step (1) with a mixture containing the precursor of the outer active component; (3) Activate the product from step (2); The inner layer active component precursor and the outer layer active component precursor each independently include the main active component precursor and the auxiliary active component precursor. The main active component precursors of the inner layer active component precursor and the outer layer active component precursor each independently include vanadium oxide precursor, and the amount of vanadium oxide precursor is such that the weight ratio of vanadium oxide in the inner layer active component and the outer layer active component, calculated as V2O5, in the obtained catalyst is 1:0.65-1.

1. In the inner layer active component precursor, the main active component precursors also include phosphorus oxide precursors, cesium oxide precursors, and titanium oxide precursors, and the amounts of phosphorus oxide precursors, cesium oxide precursors, and titanium oxide precursors are such that the weight ratio of vanadium oxide (calculated as V2O5), phosphorus oxide (calculated as P), cesium oxide (calculated as Cs), and titanium oxide (calculated as TiO2) in the obtained inner layer active component is 100:2-3:4-5:1000-1400; in the inner layer active component precursor, the amount of auxiliary active component precursor is such that the weight ratio of vanadium oxide (calculated as V2O5) to auxiliary active component (calculated as metal element oxide) in the obtained inner layer active component is 1:0.3-0.5; the auxiliary active component precursors include niobium, antimony, and zirconium oxide precursors. In the outer active component precursor, the main active component precursor also includes cesium oxide precursor and titanium oxide precursor, and the amount of cesium oxide precursor and titanium oxide precursor is such that the weight ratio of vanadium oxide (calculated as V2O5), cesium oxide (calculated as Cs), and titanium oxide (calculated as TiO2) in the obtained outer active component is 100:8.5-10:1500-1600; in the outer active component precursor, the amount of auxiliary active component precursor is such that the weight ratio of vanadium oxide (calculated as V2O5) and auxiliary active component (calculated as metal element oxide) in the obtained outer active component is 1:0.3-0.5; the auxiliary active component precursor includes niobium and antimony oxide precursors.

8. The method according to claim 7, wherein, The amount of inner layer active component precursor and outer layer active component precursor used results in a catalyst in which, relative to 2000g of support, the content of inner layer active component is 120-140g and the content of outer layer active component is 135-155g. And / or, the amounts of the inner active component precursor and the outer active component precursor are such that the weight ratio of the inner active component to the outer active component in the obtained catalyst is 1:1-1.

2.

9. The method according to claim 7, wherein, In the inner active component precursor, the amount of auxiliary active component precursor used is such that the weight ratio of vanadium oxide (calculated as V2O5) to auxiliary active component (calculated as metal element oxide) in the obtained inner active component is 1:0.35-0.

45. And / or, in the outer active component precursor, the amount of auxiliary active component precursor used is such that the weight ratio of vanadium oxide (calculated as V2O5) to auxiliary active component (calculated as metal element oxide) in the resulting outer active component is 1:0.31-0.

42.

10. The method according to claim 7, wherein, In the inner active component precursor, the amounts of niobium precursor, antimony precursor and zirconium precursor are such that the weight ratio of niobium oxide (calculated as Nb2O5), zirconium oxide (calculated as ZrO2), and antimony oxide (calculated as Sb2O3) in the obtained inner active component is 0.03-0.2:0.05-0.2:

1. In the outer active component precursor, the amounts of niobium precursor and antimony precursor are such that the weight ratio of niobium oxide (calculated as Nb2O5) to antimony oxide (calculated as Sb2O3) in the resulting outer active component is 0.1-0.2:

1.

11. The method according to claim 7, wherein, In the inner active component precursor, the amounts of niobium precursor, antimony precursor and zirconium precursor are such that the weight ratio of niobium oxide (calculated as Nb2O5), zirconium oxide (calculated as ZrO2), and antimony oxide (calculated as Sb2O3) in the obtained inner active component is 0.04-0.1:0.08-0.11:

1. In the outer active component precursor, the amounts of niobium precursor and antimony precursor are such that the weight ratio of niobium oxide (calculated as Nb2O5) to antimony oxide (calculated as Sb2O3) in the resulting outer active component is 0.12-0.13:

1.

12. The catalyst prepared by the method according to any one of claims 7-11.

13. A method for producing phthalic anhydride, characterized in that, The method comprises: contacting naphthalene with an oxygen-containing gas in the presence of the catalyst according to any one of claims 1-6 and 12; Alternatively, the method may include: preparing a catalyst according to any one of claims 7-11, and then contacting naphthalene with an oxygen-containing gas in the presence of the catalyst.

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