CN112642453A

CN112642453A - Catalyst for preparing phthalic anhydride by naphthalene oxidation and preparation method thereof

Info

Publication number: CN112642453A
Application number: CN201910967115.0A
Authority: CN
Inventors: 安欣; 刘玉芬; 袁滨; 师慧敏; 张东顺; 张作峰; 冯晔; 董岩
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Current assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Priority date: 2019-10-12
Filing date: 2019-10-12
Publication date: 2021-04-13

Abstract

The invention provides a catalyst for preparing phthalic anhydride by naphthalene oxidation, which comprises a carrier, an active component and a heat conduction material. The catalyst for preparing phthalic anhydride by naphthalene oxidation has strong heat release section added with proper amount of material with good heat transfer performance, which is favorable for quickly transferring heat and removing heat, and is evaluated on 2000ml bed layer, the molten salt temperature is 343 deg.C, the naphthalene concentration is 84g/Nm³The mass yield of the phthalic anhydride can reach 108.12 percent.

Description

Catalyst for preparing phthalic anhydride by naphthalene oxidation and preparation method thereof

Technical Field

The invention belongs to the technical field of catalysts for preparing phthalic anhydride by oxidation, and particularly relates to a catalyst for preparing phthalic anhydride by naphthalene oxidation and a preparation method thereof.

Background

Phthalic Anhydride (PA) is an important organic chemical raw material, which is considered as one of ten organic chemical raw materials, and the PA is mainly used for producing a plasticizer, alkyd resin and Unsaturated Polyester Resin (UPR) as an intermediate, wherein the plasticizer is mainly used for PVC compounds and accounts for about 57 percent of the worldwide PA consumption; alkyd resins account for about 19% of the worldwide PA consumption and are widely used in the production of solvent-borne coatings and agricultural mulch films. Unsaturated Polyester Resins (UPR) account for about 15% of the worldwide PA consumption, primarily for the construction and transportation industries, other uses including applications in dyes and various specialty chemicals.

At present, patents for preparing phthalic anhydride by naphthalene oxidation mainly focus on optimization of an auxiliary agent and a formula, BASF company develops a novel catalyst for a process for preparing phthalic anhydride by mixed oxidation of ortho-naphthalene and naphthalene, and the active components of the catalyst are vanadium oxide, titanium dioxide, and mixed oxides which can contain cesium compounds, phosphorus compounds, antimony oxide and specific metals (such as lithium, potassium, rubidium and the like). The preparation method of the catalyst comprises the steps of coating one or more shell-shaped coatings on an inert porous carrier, wherein the highest alkali metal content of one catalyst layer A is met; the catalyst layer B, C and the like located after the catalyst layer a have different alkali metal contents in the flow direction from 0% to 90% of the catalyst layer a, and the alkali metal content of each catalyst layer is higher than that of the catalyst layer following in the flow direction.

The company clariant developed a multilayer catalyst for the preparation of phthalic anhydride with a catalyst arrangement having a first catalyst layer on the gas inlet side and at least one second catalyst layer of different catalytic activity downstream of the first catalyst layer in the gas passage flow direction.

The naphthalene method imported phthalic anhydride catalyst used in China is mainly from BASF company. The catalyst is divided into 3-6 sections of beds, the feeding amount of raw materials is 60-80g/Nm 3, and the purity conversion yield of phthalic anhydride is 102-103% in the first year.

The reaction for preparing the phthalic anhydride by oxidizing the naphthalene belongs to a typical oxidation exothermic reaction, the heat release is violent, the self heat transfer capability of a reaction catalyst is enhanced, the temperature of a reaction area can be reduced, the product is prevented from further deep oxidation to generate carbon oxides, and the yield of the target product phthalic anhydride is improved.

Disclosure of Invention

The invention aims to solve the technical problem of heat transfer of the reaction in the strong heat release section of the catalyst, and the material with good heat transfer performance is added in sections to strengthen the heat transfer and reduce deep oxidation, thereby improving the performance of the catalyst.

The first aspect of the invention provides a catalyst for preparing phthalic anhydride (abbreviated as phthalic anhydride) by naphthalene oxidation, which has higher reaction load, raw material conversion rate and phthalic anhydride quality yield.

In a second aspect, the present invention provides a process for preparing the catalyst of the first aspect.

The third aspect of the invention provides a method for preparing phthalic anhydride by naphthalene oxidation.

According to a first aspect of the present invention, the catalyst for preparing phthalic anhydride by naphthalene oxidation comprises a carrier, an active component and a heat conducting material.

According to some embodiments of the invention, the active components comprise a main active component comprising a vanadium compound, a phosphorus compound, a potassium compound and optionally a cesium compound, an auxiliary and titanium dioxide.

According to some embodiments of the present invention, the active ingredient is present in a proportion of 5% to 25%, preferably 7% to 17%, by mass of the carrier.

According to some embodiments of the invention, the thermally conductive material is present in an amount of 0.5 to 8.5% by mass, e.g., 0.5%, 1.0%, 1.2%, 1.5%, 1.6%, 1.8%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5% and any value therebetween, based on the total weight of the active component and the thermally conductive material.

According to some embodiments of the invention, the thermally conductive material is present in an amount of 1-5% by weight, based on the total weight of the active component and the thermally conductive material.

According to some embodiments of the invention, the active component comprises V, based on the total weight of the active component and the thermally conductive material₂O₅5 to 18 percent of vanadium, 0.01 to 0.3 percent of phosphorus calculated by P, 0 to 1 percent of cesium calculated by Cs, 0.01 to 0.5 percent of potassium calculated by K, 0.1 to 10 percent of auxiliary agent calculated by auxiliary agent element oxide and the balance of TiO₂。

According to some embodiments of the invention, the thermally conductive material is selected from one or more of graphene, graphite powder and carbon fibre material.

According to some embodiments of the invention, the thermally conductive material is in the shape of one or more of granules, cylinders, rods.

According to some embodiments of the invention, the thermally conductive material has a size of 20 μm or less, preferably 10 μm or less, which, when the material particles are large, results in clogging of the nozzle during spraying, affecting the spraying.

According to some embodiments of the invention, the vanadium compound comprises one or more selected from the group consisting of ammonium metavanadate, vanadium pentoxide and sodium vanadate.

According to some embodiments of the invention, the phosphorus compound comprises one or more selected from the group consisting of monoammonium phosphate, triammonium phosphate, and phosphorus pentoxide.

According to some embodiments of the invention, the cesium compound comprises one or more selected from the group consisting of cesium nitrate, cesium sulfate, cesium chloride and cesium carbonate.

According to some embodiments of the invention, the potassium compound comprises one or more selected from the group consisting of potassium nitrate, potassium sulfate, potassium chloride and potassium bicarbonate.

According to some embodiments of the invention, the promoter is selected from one or more of the oxides of rubidium, cerium, niobium, chromium, tungsten, iron, silver, cobalt, gold, gallium, indium, antimony, bismuth, zirconium, erbium, tungsten and tin.

According to some embodiments of the invention, the titanium dioxide is anatase titanium dioxide having a specific surface area of 10m²/g-30m²Per g, preferably 15m²/g-25m²/g。

According to some embodiments of the invention, the support is selected from one or more of talc, silicon carbide, aluminum silicate, quartz and ceramic.

According to a second aspect of the present invention, the above catalyst preparation method comprises the steps of:

step S1: mixing a mixed solution, titanium dioxide, an auxiliary agent, a heat conduction material and a binder to obtain a catalytic active component slurry, wherein the mixed solution comprises a solvent, a reducing agent and a main active component, and preferably the viscosity of the slurry is 10 Pa.S-40 Pa.S, more preferably 12 Pa.S-25 Pa.S;

step S2: spraying the catalytic active component slurry onto the carrier and drying.

According to some embodiments of the invention, the reducing agent is oxalic acid. Oxalic acid as the reducer of ammonium metavanadate is first oxidized and reduced in solution to produce one kind of complex (NH)₄)₂[V₂O₂(C₂O₄)₃]Wherein the valence state of the vanadium is +4, the complex can be further heated and decomposed in the activation process, and then an active phase V is generated₂MoO₈. The reduction degree of ammonium metavanadate can be controlled by controlling the addition of oxalic acid, so that the composition and the content V of the final active phase are influenced₂MoO₈Affecting the final reaction performance of the catalyst.

According to some embodiments of the invention, the solvent is a mixed solution of water and a water-soluble organic solvent.

According to some embodiments of the invention, the water soluble organic solvent is selected from one or more of methanol, ethanol, formamide and N, N-dimethylformamide.

According to some embodiments of the present invention, the mass ratio of the water-soluble organic solvent to water is (0-0.4):1, preferably (0.1-0.3): 1.

According to some embodiments of the invention, the adhesive comprises one or more selected from the group consisting of vinyl acetate/acrylate, vinyl acetate/ethylene, vinyl acetate/maleate and acrylic acid/maleic acid copolymers.

According to some embodiments of the invention, the viscosity of the slurry in step S1 is 10 Pa.S-40 Pa.S, more preferably 12 Pa.S-25 Pa.S

According to some embodiments of the present invention, the catalyst active ingredient slurry viscosity is controlled by controlling the amount of the binder added in step S1.

According to some embodiments of the present invention, the slurry of the catalytically active component is sprayed onto the surface of the support at a temperature of the support in the range of 50 to 150 ℃ in step S2.

According to some embodiments of the present invention, the slurry of the catalytically active component is sprayed onto the surface of the support at a temperature of the support of 80 to 130 ℃ in step S2.

According to some embodiments of the invention, the sprayed metal support is dried using hot air.

According to some embodiments of the present invention, the temperature of the hot air is 80-150 ℃, preferably 100-120 ℃.

In some preferred embodiments of the invention, the spraying amount of the catalytic active component of the catalyst is controlled by the rotating drum rotating speed, the spraying rate, the loss rate and the spraying time, the activity of the catalyst is affected due to insufficient loading of the active component, the conversion rate of the raw material is low, and the deep oxidation of the catalyst is serious, the number of byproducts is large, and the quality and yield of the phthalic anhydride are reduced due to excessive loading of the active component. The mass content of the part of the spraying catalytic active component is required to reach 5-25 percent of the total mass, and is preferably 7-17 percent.

According to a third aspect of the present invention, the method for preparing phthalic anhydride by naphthalene oxidation comprises introducing mixed gas containing naphthalene into a fixed bed reactor for reaction, wherein the fixed bed reactor comprises an a-stage catalyst, a B-stage catalyst, a C-stage catalyst and a D-stage catalyst which are sequentially filled along the direction from the inlet to the outlet of the mixed gas containing naphthalene, wherein the a-stage catalyst is the catalyst according to the first aspect or the catalyst obtained by the preparation method according to the second aspect.

According to some embodiments of the invention, the catalyst of the second aspect is a catalyst of the first aspect or a catalyst obtained by the preparation method of the second aspect.

According to some embodiments of the invention, the C-stage catalyst does not contain a thermally conductive material.

According to some embodiments of the invention, the stage D catalyst does not contain a thermally conductive material.

According to some embodiments of the present invention, the catalyst of stage C and the catalyst of stage D are catalysts conventionally used in reactions for producing phthalic anhydride by the oxidation of naphthalene.

According to some embodiments of the invention, the stage C and D catalysts comprise a support and an active component, the active component comprising a primary active component comprising a vanadium compound, a phosphorus compound, a potassium compound, and optionally a cesium compound, a promoter selected from one or more oxides of rubidium, cerium, niobium, chromium, tungsten, iron, silver, cobalt, gold, gallium, indium, antimony, bismuth, zirconium, erbium, tungsten, and tin, and titanium dioxide, the support selected from one or more of talc, silicon carbide, aluminum silicate, quartz, and ceramic.

According to some embodiments of the present invention, the active component accounts for 5% to 25%, preferably 7% to 17%, of the mass of the carrier in the C-stage catalyst and the D-stage catalyst.

According to some embodiments of the invention, in the C-stage catalyst and the D-stage catalyst, the active component comprises at V₂O₅5 to 18 percent of vanadium, 0.01 to 0.3 percent of phosphorus calculated by P, 0 to 1 percent of cesium calculated by Cs, 0.01 to 0.5 percent of potassium calculated by K, 0.1 to 10 percent of auxiliary agent calculated by auxiliary agent element oxide and the balance of TiO₂。

According to some embodiments of the invention, in the C-stage catalyst and the D-stage catalyst, the vanadium compound comprises one or more selected from the group consisting of ammonium metavanadate, vanadium pentoxide, and sodium vanadate; the phosphorus compound comprises one or more selected from ammonium dihydrogen phosphate, triammonium phosphate and phosphorus pentoxide; the cesium compound includes one or more selected from cesium nitrate, cesium sulfate, cesium chloride, and cesium carbonate; the potassium compound comprises one or more selected from potassium nitrate, potassium sulfate, potassium chloride and potassium bicarbonate.

According to some embodiments of the invention, in the C-stage catalyst and the D-stage catalyst, the titanium dioxide is anatase titanium dioxide and has a specific surface area of 10m²/g-30m²Per g, preferably 15m²/g-25m²/g。

The reaction for preparing the phthalic anhydride by oxidizing the naphthalene belongs to a typical oxidation exothermic reaction, the heat release at the front section is violent, the self heat transfer capability of a catalyst at the front section of the reaction is enhanced, the temperature of a reaction area can be reduced, the product is prevented from further deeply oxidizing to generate carbon oxides, and therefore the yield of the target product phthalic anhydride is improved. The inventor creatively discovers that for a four-section bed catalyst system commonly used in industry, the reaction is mainly concentrated on the section A and the section B, and the phthalic anhydride catalyst is improved by adding a proper amount of heat conducting material in sections, so that the heat transfer performance of the catalyst at the front section of the reaction can be improved, the heat conduction and the shift-out of the reaction can be better realized, the overall performance of the catalyst is improved, and meanwhile, compared with the condition that the heat conducting material is added into the whole four-section catalyst, the heat dissipation is strengthened in the high-temperature section with strong heat release of the catalyst according to the bed temperature distribution condition, and the invention has better effect on balancing the reaction process and improving.

According to some embodiments of the invention, the molten salt temperature of the reaction is 300-.

According to some embodiments of the invention, the naphthalene-containing mixed gas has a space velocity of 1500h^-1-5000h^-1Preferably 3000h^-1-4000h^-1。

According to some embodiments of the invention, the pressure used for the reaction may be negative, atmospheric and pressurized, with atmospheric reactions being preferred.

The catalyst provided by the invention is used for producing phthalic anhydride by oxidizing naphthalene, and the naphthalene concentration in the mixed gasGenerally 60-80g/Nm³The concentration is the concentration which is industrially conventional, and the naphthalene concentration is the gram number of naphthalene contained in a unit volume of air, and the higher the value, the higher the naphthalene content in the air.

According to some embodiments of the invention, the heating and removing heat is performed using a molten salt bath. In the evaluation of the reaction, the temperature in the catalyst bed was not uniform from top to bottom, wherein the highest value of the temperature region was called the hot spot temperature of the catalyst, and the temperature was measured by means of a thermocouple by means of the temperature of the bed.

The catalyst for preparing phthalic anhydride by naphthalene oxidation provided by the invention is added with a proper amount of material with good heat transfer performance in a strong heat release section, which is beneficial to quickly transferring heat and removing heat, and the catalyst is used for evaluation on a 2000ml bed layer, wherein the temperature of molten salt is 343 ℃, and the concentration of naphthalene is 84g/Nm³The mass yield of the phthalic anhydride can reach 108.12 percent.

Detailed Description

For easy understanding of the present invention, the present invention will be described in detail with reference to examples, which are provided for illustrative purposes only and are not intended to limit the scope of the present invention.

The raw materials or components used in the present invention can be commercially or conventionally prepared unless otherwise specified, and the quantitative tests in the following examples are set up in three repeated experiments, and the results are averaged.

Example 1

Preparation of section A:

step A: a solution was prepared by adding water to 51.26 g of ammonium metavanadate, 115.33 g of oxalic acid, 4.93 g of cesium sulfate, 5.72 g of niobium oxalate, 0.61 g of potassium sulfate, 220ml of formamide, and water.

And B: pouring the solution, 13.46 g of heat conduction material, 663.24 g of titanium dioxide, 0.84 g of silver oxide and 11.62 g of antimony trioxide into a ball mill, adding vinyl acetate/ethylene copolymer emulsion with the mass of 10-15% of solid matter, carrying out ball milling for 2-4 hours, emulsifying the catalytic active component into uniform suspension emulsion, and controlling the viscosity of the emulsion to be 12-16 Pa.S.

And C: placing 2000 g of a carrier magnetic ring with the outer diameter of 8mm, the height of 6mm and the wall thickness of 1.5mm in a rotary drum, and controlling the speed of the rotary drum to be 5-10 rpm; adding the prepared emulsion into a stirring tank of a feed liquid spraying system and stirring; starting a hot air blower, penetrating hot air into the rotary drum, preheating the carrier ring, starting a feeding nozzle when the temperature of the carrier reaches 80-130 ℃, preferably 110-130 ℃, controlling the temperature of the hot air at 100-120 ℃, and controlling the spraying speed of the feed liquid at 30-60 ml/min; the catalytic active substance emulsion is sprayed on the surface of the carrier magnetic ring through a nozzle and is dried quickly by hot air. The content of the catalytic active substance reaches 7-17% of the weight of the carrier, and the A-section catalyst is prepared after the spraying is finished.

B, preparation:

step A: a solution was prepared by adding water to 56.27 g of ammonium metavanadate, 131.46 g of oxalic acid, 5.21 g of cesium sulfate, 1.51 g of ammonium dihydrogen phosphate, 6.15 g of niobium oxalate, 0.63 g of potassium sulfate, and 220ml of formamide.

And B: pouring the solution, 13.46 g of heat conduction material, 663.24 g of titanium dioxide and 11.15 g of antimony trioxide into a ball mill, adding vinyl acetate/ethylene copolymer emulsion with the mass of 10-15% of solid matter, ball milling for 2-4 hours, emulsifying the catalytic active component into uniform suspension emulsion, and controlling the viscosity of the emulsion to be 12-16 Pa.S.

And C: placing 2000 g of a carrier magnetic ring with the outer diameter of 8mm, the height of 6mm and the wall thickness of 1.5mm in a rotary drum, and controlling the speed of the rotary drum to be 5-10 rpm; adding the prepared emulsion into a stirring tank of a feed liquid spraying system and stirring; starting a hot air blower, penetrating hot air into the rotary drum, preheating the carrier ring, starting a feeding nozzle when the temperature of the carrier reaches 80-130 ℃, preferably 110-130 ℃, controlling the temperature of the hot air at 100-120 ℃, and controlling the spraying speed of the feed liquid at 30-60 ml/min; the catalytic active substance emulsion is sprayed on the surface of the carrier magnetic ring through a nozzle and is dried quickly by hot air. The content of the catalytic active substance reaches 7-17% of the weight of the carrier, and the B-section catalyst is prepared after the spraying is finished.

C, preparation:

step A: a solution was prepared by adding water to 62.33 g of ammonium metavanadate, 144.52 g of oxalic acid, 2.99 g of cesium sulfate, 3.87 g of ammonium dihydrogen phosphate, 3.67 g of niobium oxalate, 0.19 g of potassium sulfate, 3.41 g of zirconium sulfate tetrahydrate, and 220ml of formamide.

And B: pouring the solution, 663.24 g of titanium dioxide and 16.65 g of antimony trioxide into a ball mill, adding vinyl acetate/ethylene copolymer emulsion with the mass of 10-15% of that of solid substances, carrying out ball milling for 2-4 hours, emulsifying the catalytic active component into uniform suspension emulsion, and controlling the viscosity of the emulsion to be 12-16 Pa.S.

And C: placing 2000 g of a carrier magnetic ring with the outer diameter of 8mm, the height of 6mm and the wall thickness of 1.5mm in a rotary drum, and controlling the speed of the rotary drum to be 5-10 rpm; adding the prepared emulsion into a stirring tank of a feed liquid spraying system and stirring; starting a hot air blower, penetrating hot air into the rotary drum, preheating the carrier ring, starting a feeding nozzle when the temperature of the carrier reaches 80-130 ℃, preferably 110-130 ℃, controlling the temperature of the hot air at 100-120 ℃, and controlling the spraying speed of the feed liquid at 30-60 ml/min; the catalytic active substance emulsion is sprayed on the surface of the carrier magnetic ring through a nozzle and is dried quickly by hot air. The content of the catalytic active substance reaches 7-17% of the weight of the carrier, and the C-section catalyst is prepared after the spraying is finished.

D, preparation:

step A: 78.56 g of ammonium metavanadate, 182.45 g of oxalic acid, 0.36 g of cesium sulfate, 4.93 g of ammonium dihydrogen phosphate, 6.84 g of niobium oxalate, 4.19 g of zirconium sulfate tetrahydrate and 220ml of formamide are added with water to prepare a solution.

And B: pouring the solution, 663.24 g of titanium dioxide and 2.44 g of antimony trioxide into a ball mill, adding vinyl acetate/ethylene copolymer emulsion with the mass of 10-15% of that of solid substances, carrying out ball milling for 2-4 hours, emulsifying the catalytic active component into uniform suspension emulsion, and controlling the viscosity of the emulsion to be 12-16 Pa.S.

And C: placing 2000 g of a carrier magnetic ring with the outer diameter of 8mm, the height of 6mm and the wall thickness of 1.5mm in a rotary drum, and controlling the speed of the rotary drum to be 5-10 rpm; adding the prepared emulsion into a stirring tank of a feed liquid spraying system and stirring; starting a hot air blower, penetrating hot air into the rotary drum, preheating the carrier ring, starting a feeding nozzle when the temperature of the carrier reaches 80-130 ℃, preferably 110-130 ℃, controlling the temperature of the hot air at 100-120 ℃, and controlling the spraying speed of the feed liquid at 30-60 ml/min; the catalytic active substance emulsion is sprayed on the surface of the carrier magnetic ring through a nozzle and is dried quickly by hot air. The content of the catalytic active substance reaches 7-17% of the weight of the carrier, and the D-section catalyst is prepared after the spraying is finished.

Example 2

Preparation of section A:

B, preparation:

And B: pouring the solution, 663.24 g of titanium dioxide and 11.15 g of antimony trioxide into a ball mill, adding vinyl acetate/ethylene copolymer emulsion with the mass of 10-15% of that of solid substances, carrying out ball milling for 2-4 hours, emulsifying the catalytic active component into uniform suspension emulsion, and controlling the viscosity of the emulsion to be 12-16 Pa.S.

C, preparation:

D, preparation:

Example 3

Preparation of section A:

And B: pouring the solution, 7.35 g of heat conduction material, 663.24 g of titanium dioxide, 0.84 g of silver oxide and 11.62 g of antimony trioxide into a ball mill, adding vinyl acetate/ethylene copolymer emulsion with the mass of 10-15% of solid matter, carrying out ball milling for 2-4 hours, emulsifying the catalytic active component into uniform suspension emulsion, and controlling the viscosity of the emulsion to be 12-16 Pa.S.

B, preparation:

C, preparation:

D, preparation:

Example 4

Preparation of section A:

And B: pouring the solution, 37.93 g of heat conduction material, 663.24 g of titanium dioxide, 0.84 g of silver oxide and 11.62 g of antimony trioxide into a ball mill, adding vinyl acetate/ethylene copolymer emulsion with the mass of 10-15% of that of solid matters, carrying out ball milling for 2-4 hours, emulsifying the catalytic active component into uniform suspension emulsion, and controlling the viscosity of the emulsion to be 12-16 Pa.S.

B, preparation:

C, preparation:

D, preparation:

Example 5

Preparation of section A:

B, preparation:

C, preparation:

And B: pouring the solution, 13.46 g of heat conduction material, 663.24 g of titanium dioxide and 16.65 g of antimony trioxide into a ball mill, adding vinyl acetate/ethylene copolymer emulsion with the mass of 10-15% of solid matter, ball milling for 2-4 hours, emulsifying the catalytic active component into uniform suspension emulsion, and controlling the viscosity of the emulsion to be 12-16 Pa.S.

D, preparation:

And B: pouring the solution, 13.46 g of heat conduction material, 663.24 g of titanium dioxide and 2.44 g of antimony trioxide into a ball mill, adding vinyl acetate/ethylene copolymer emulsion with the mass of 10-15% of solid matter, ball milling for 2-4 hours, emulsifying the catalytic active component into uniform suspension emulsion, and controlling the viscosity of the emulsion to be 12-16 Pa.S.

Example 6

Preparation of section A:

B, preparation:

C, preparation:

D, preparation:

Example 7

Preparation of section A:

And B: pouring the solution, 3.44 g of heat conduction material, 663.24 g of titanium dioxide, 0.84 g of silver oxide and 11.62 g of antimony trioxide into a ball mill, adding vinyl acetate/ethylene copolymer emulsion with the mass of 10-15% of solid matter, carrying out ball milling for 2-4 hours, emulsifying the catalytic active component into uniform suspension emulsion, and controlling the viscosity of the emulsion to be 12-16 Pa.S.

B, preparation:

C, preparation:

D, preparation:

Example 8

Preparation of section A:

And B: pouring the solution, 63.62 g of heat conduction material, 663.24 g of titanium dioxide, 0.84 g of silver oxide and 11.62 g of antimony trioxide into a ball mill, adding vinyl acetate/ethylene copolymer emulsion with the mass of 10-15% of that of solid matters, carrying out ball milling for 2-4 hours, emulsifying the catalytic active component into uniform suspension emulsion, and controlling the viscosity of the emulsion to be 12-16 Pa.S.

B, preparation:

C, preparation:

D, preparation:

Comparative example 1

Preparation of section A:

And B: pouring the solution, 663.24 g of titanium dioxide, 0.84 g of silver oxide and 11.62 g of antimony trioxide into a ball mill, adding vinyl acetate/ethylene copolymer emulsion with the mass of 10-15% of solid matters, carrying out ball milling for 2-4 hours, emulsifying the catalytic active component part into uniform suspension emulsion, and controlling the viscosity of the emulsion to be 12-16 Pa.S.

And C: 2000 g of talc ring inert carrier with the outer diameter of 8mm, the height of 6mm and the wall thickness of 1.5mm is placed in a rotary drum, and the speed of the rotary drum is controlled to be 5 rpm-10 rpm; adding the prepared emulsion into a stirring tank of a feed liquid spraying system and stirring; starting a hot air blower, penetrating hot air into the rotary drum, preheating the inert carrier, starting a feeding nozzle when the temperature of the carrier reaches 80-130 ℃, preferably 110-130 ℃, and controlling the spraying speed of the feed liquid to be 30-60 ml/min; the suspension emulsion of the catalytically active substance is sprayed onto the surface of the inert carrier by means of a nozzle and dried rapidly by means of hot air. The content of the catalytic active substance reaches 7-17% of the weight of the carrier, and the A-section catalyst is prepared after the spraying is finished.

B, preparation:

C, preparation:

D, preparation:

Catalyst evaluation 1

A single-bed reactor simulating industrial production conditions is adopted to examine the performance of the catalyst, the inner diameter of a fixed single-bed reactor is 29mm, the length of the fixed single-bed reactor is 4400mm, the outside of a reaction tube adopts a molten salt circulating heat transfer mode, and a multipoint temperature measurement system is arranged in the reaction tube. The phthalic anhydride catalyst adopts a multistage filling mode, and a catalyst D, a catalyst C, a catalyst B and a catalyst A are filled from bottom to top, wherein the filling height of the catalyst D is 500mm, the filling height of the catalyst C is 800mm, the filling height of the catalyst B is 700mm, and the filling height of the catalyst A is 1400 mm. The outlet of the reactor is connected with an analysis system and a reactant collecting system.

All prepared catalysts are evaluated under the same condition, the catalysts are activated for 4 to 24 hours in oxidizing atmosphere, the salt bath temperature is controlled to be 300 to 450 ℃, the preference is 330 to 400 ℃ after feeding, and the space velocity is 1500h^-1～5000h^-1Preferably 3000h^-1～4000h^-1. Gradually increasing the concentration of naphthalene feeding, sampling and analyzing all conditions at the outlet of the reactor, and checking the performance indexes of the highest load and the optimal yield of the catalyst. The example evaluation results and the comparative example evaluation results of the catalyst evaluation experiments are shown in table 1.

TABLE 1

It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.

Claims

1. A catalyst for preparing phthalic anhydride by oxidizing naphthalene comprises a carrier, an active component and a heat conducting material.

2. The catalyst of claim 1, wherein the active components comprise a main active component, an adjunct and titanium dioxide, the main active component comprising a vanadium compound, a phosphorus compound, a potassium compound and optionally a cesium compound;

and/or the active component accounts for 5 to 25 percent, preferably 7 to 17 percent, based on the mass of the carrier;

and/or the mass content of the heat conduction material is 0.5-8.5%, preferably 1-5% based on the total weight of the active component and the heat conduction material, wherein the active component comprises V₂O₅5 to 18 percent of vanadium, 0.01 to 0.3 percent of phosphorus calculated by P, 0 to 1 percent of cesium calculated by Cs, 0.01 to 0.5 percent of potassium calculated by K, 0.1 to 10 percent of auxiliary agent calculated by auxiliary agent element oxide and the balance of TiO₂。

3. Catalyst according to claim 1 or 2, characterized in that the thermally conductive material is selected from one or more of graphene, graphite powder and carbon fiber material, preferably the thermally conductive material is in the shape of one or more of granules, cylinders, rods and/or the thermally conductive material has a size of 20 μm or less, preferably 10 μm or less.

4. A catalyst according to any one of claims 1 to 3, wherein the vanadium compound comprises one or more selected from ammonium metavanadate, vanadium pentoxide and sodium vanadate; and/or the phosphorus compound comprises one or more selected from monoammonium phosphate, triammonium phosphate and phosphorus pentoxide; and/or the cesium compound comprises one or more selected from cesium nitrate, cesium sulfate, cesium chloride and cesium carbonate; and/or the potassium compound comprises one or more selected from potassium nitrate, potassium sulphate, potassium chloride and potassium bicarbonate;

and/or the auxiliary agent is selected from one or more of rubidium, cerium, niobium, chromium, tungsten, iron, silver, cobalt, gold, gallium, indium, antimony, bismuth, zirconium, erbium, tungsten and tin oxides;

and/or the titanium dioxide is anatase titanium dioxide with the specific surface area of 10m²/g-30m²Per g, preferably 15m²/g-25m²/g；

And/or the carrier is selected from one or more of talc, silicon carbide, aluminium silicate, quartz and ceramic.

5. A method for preparing a catalyst according to any one of claims 1 to 4, comprising the steps of:

6. The method of claim 5, wherein the reducing agent is oxalic acid; and/or the solvent is a mixed solution of water and a water-soluble organic solvent, preferably, the water-soluble organic solvent is selected from one or more of methanol, ethanol, formamide and N, N-dimethyl amide; and/or the mass ratio of the water-soluble organic solvent to water is (0-0.4) to 1, preferably (0.1-0.3) to 1;

and/or the adhesive comprises one or more selected from the group consisting of vinyl acetate/acrylate, vinyl acetate/ethylene, vinyl acetate/maleate and acrylic acid/maleic acid copolymers.

7. The method according to claim 5 or 6, characterized in that in step S2, the slurry of the catalytically active component is sprayed onto the surface of the support at a temperature of the support of 50-150 ℃, preferably 80-130 ℃; and/or drying the sprayed metal carrier by using hot air, wherein the temperature of the hot air is 80-150 ℃, and preferably 100-120 ℃.

8. A method for preparing phthalic anhydride by naphthalene oxidation comprises introducing mixed gas containing naphthalene into a fixed bed reactor for reaction, wherein the fixed bed reactor comprises an A-stage catalyst, a B-stage catalyst, a C-stage catalyst and a D-stage catalyst which are sequentially filled along the direction from an inlet to an outlet of the mixed gas containing naphthalene, and the A-stage catalyst is the catalyst of any one of claims 1 to 4 or the catalyst obtained by the preparation method of any one of claims 5 to 7.

9. The method according to claim 8, wherein the catalyst of stage B is the catalyst of any one of claims 1 to 4 or the catalyst obtained by the production method according to any one of claims 5 to 7, the catalyst of stage C and the catalyst of stage D do not contain a thermally conductive material,

preferably, the catalysts of stage C and D include a support and active components, the active components including a main active component including a vanadium compound, a phosphorus compound, a potassium compound, and optionally a cesium compound, a promoter selected from one or more oxides of rubidium, cerium, niobium, chromium, tungsten, iron, silver, cobalt, gold, gallium, indium, antimony, bismuth, zirconium, erbium, tungsten, and tin, and an active component selected from one or more of talc, silicon carbide, aluminum silicate, quartz, and ceramic.

10. The method according to claim 8 or 9, characterized in that the molten salt temperature of the reaction is 300-450 ℃, preferably 330-400 ℃; and/or the space velocity of the mixed gas containing the naphthalene is 1500h^-1-5000h^-1Preferably 3000h^-1-4000h^-1。