Catalyst for preparing 9-fluorenone through selective oxidation of fluorene as well as preparation method and application of catalyst

Abstract

The invention discloses a catalyst for preparing 9-fluorenone through selective oxidation of fluorene and a preparation method and application thereof.The catalyst comprises a carrier and active components, the active components comprise a vanadium element, a titanium element, a potassium element, a nickel element and an auxiliary element, the additive element is selected from at least one of magnesium element, calcium element, strontium element, copper element, zinc element, silver element, iron element, bismuth element, cobalt element, zirconium element, niobium element and tungsten element. According to the catalyst, the selectivity of 9-fluorenone can be improved, reaction hot spots are reduced, and the performance of the catalyst is improved.

Description

Technical Field

[0001] The present invention belongs to the field of catalysts, and particularly relates to a catalyst for the selective oxidation of fluorene to prepare 9-fluorenone. Background Art

[0002] 9-Fluorenone is an important chemical raw material, widely used in the fields of medicine, pesticides, dyes, polymer materials, photosensitive materials, etc. As a monomer for the synthesis of high-end camera materials, it is indispensable for autonomous driving cameras, face recognition, and robots.

[0003] The air-liquid phase oxidation method is the main industrial method for the synthesis of 9-fluorenone in China. Alkaline compounds such as sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate are used as catalysts, and ethanol, quinoline, p-xylene, pyridine, glacial acetic acid, etc. are used as solvents. Fluorene is used as a raw material for catalytic oxidation to prepare 9-fluorenone. This process has the advantages of high product selectivity, low reaction temperature, and high product selectivity. However, the catalyst has poor recyclability and high price; a large amount of solvent needs to be recycled and a large amount of emulsified wastewater needs to be treated; the reaction scale is small and discontinuous.

[0004] Air-gas phase oxidation can avoid the use of a large amount of solvents and the problem of generating emulsified wastewater, and is easy to achieve large-scale production. It is a method that has gradually emerged in recent years. However, inappropriate reaction conditions and catalyst selection can still produce such by-products, and even cause deep oxidation, generating various impurities such as phthalic anhydride that are difficult to separate, as well as by-products such as carbon dioxide. Summary of the Invention

[0005] In order to overcome the problems existing in the prior art, the present invention provides a catalyst for the selective oxidation of fluorene to prepare 9-fluorenone, its preparation method and application, which can be used for the selective oxidation of fluorene to prepare 9-fluorenone. Among them, the gas-phase partial oxidation of fluorene to 9-fluorenone is a violent reaction process that generates a large amount of heat. If the heat cannot be removed in time during the production process, it will cause local overheating of the catalyst bed layer, and further deep oxidation will occur, thereby reducing the selectivity and yield of 9-fluorenone. Therefore, screening a suitable catalyst can improve the selectivity of 9-fluorenone, reduce the reaction hot spot, and improve the performance of the catalyst.

[0006] One of the purposes of the present invention is to provide a catalyst for the selective oxidation of fluorene to prepare 9-fluorenone. The catalyst includes a carrier and an active component. Among them, the active component includes vanadium element, titanium element, potassium element, nickel element, and a promoter element. The promoter element is selected from at least one of magnesium element, calcium element, strontium element, copper element, zinc element, silver element, iron element, bismuth element, cobalt element, zirconium element, niobium element, tungsten element (for example, at least two, at least three, or at least four).

[0007] In a preferred embodiment, the promoter element is selected from the combination of promoter element I, promoter element II, promoter element III, and promoter element IV. Promoter element I is selected from at least one of magnesium, calcium, and strontium. Promoter element II is selected from at least one of copper, zinc, and silver. Promoter element III is selected from at least one of iron, bismuth, and cobalt. Promoter element IV is selected from at least one of zirconium, niobium, and tungsten. Among them, the promoter element preferably exists in the form of an oxide or a composite oxide.

[0008] In the present invention, different types of metal promoters are introduced for compounding, which improves the reaction activity of the catalyst and reduces the molten salt temperature.

[0009] In a preferred embodiment, the carrier is mainly composed of silicon carbide.

[0010] In a further preferred embodiment, based on 100 wt% of the carrier, the silicon carbide accounts for 65 - 92 wt%, preferably 70 - 90 wt%, such as 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, or 92 wt%.

[0011] In a still further preferred embodiment, the silicon carbide is green silicon carbide, and either the α or β crystal form can be used for the carrier.

[0012] In a preferred embodiment, the carrier further contains an alkaline agent, a binder, and a carrier pore regulator.

[0013] In a further preferred embodiment, the alkaline agent is selected from at least one of magnesium oxide, sodium oxide, and potassium oxide. The binder is selected from at least one of methyl cellulose and ethyl cellulose. The carrier pore regulator is selected from at least one of diatomaceous earth and zeolite powder;

[0014] Among them, the alkaline agent in the carrier mainly functions to make the carrier alkaline; the binder mainly acts as a binder in the preparation of the carrier; the carrier pore regulator mainly provides a suitable specific surface area and voids for the carrier.

[0015] In a further preferred embodiment, based on 100 wt% of the carrier, the alkaline agent accounts for 1 - 12 wt% (such as 1 wt%, 2 wt%, 4 wt%, 6 wt%, 8 wt%, 10 wt%, or 12 wt%), the binder accounts for 5 - 12 wt% (such as 5 wt%, 6 wt%, 8 wt%, 10 wt%, or 12 wt%), and the carrier pore regulator accounts for 1 - 12 wt% (such as 1 wt%, 2 wt%, 4 wt%, 6 wt%, 8 wt%, 10 wt%, or 12 wt%).

[0016] Preferably, the carrier is obtained as follows: materials including silicon carbide, magnesium oxide, methyl cellulose, and diatomaceous earth are mixed, then extruded into a certain shape with water, and dried and calcined to obtain the carrier. Among them, the drying temperature is 100 - 160 °C, preferably 120 - 140 °C; the calcination temperature is 800 - 1500 °C, preferably 900 - 1300 °C.

[0017] According to some embodiments of the present invention, the shape of the carrier is any one of spherical, cylindrical, annular, cloverleaf-shaped, and four-leaf clover-shaped, and annular and cloverleaf-shaped are preferably selected for better heat conduction.

[0018] In a preferred embodiment, the vanadium element is derived from a vanadium-containing compound, and the vanadium-containing compound is selected from one or more of ammonium metavanadate, vanadium pentoxide, and sodium vanadate, preferably ammonium metavanadate.

[0019] In a preferred embodiment, the titanium element is derived from a titanium-containing compound, and the titanium-containing compound is selected from one or more of titanium dioxide and titanium tetrachloride, preferably titanium dioxide.

[0020] In a preferred embodiment, the potassium element is derived from a potassium-containing compound, and the potassium-containing compound is selected from one or more of potassium hydroxide, potassium nitrate, potassium carbonate, and potassium chloride.

[0021] In a preferred embodiment, the nickel element is derived from a nickel-containing compound, and the nickel-containing compound is selected from one or more of nickel nitrate, nickel sulfate, nickel chloride, and nickel oxide, preferably nickel nitrate.

[0022] In a preferred embodiment, the catalyst further contains a phosphorus element.

[0023] In a further preferred embodiment, the phosphorus element is derived from at least one of trisodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, pyrophosphoric acid, potassium phosphate, dipotassium hydrogen phosphate, and potassium dihydrogen phosphate.

[0024] In a further preferred embodiment, the molar ratio of titanium element to phosphorus element is 1:(0.0001 - 0.05), such as 1:0.0001, 1:0.001, 1:0.01, 1:0.02, 1:0.03, 1:0.04, or 1:0.05, and the molar amounts of titanium element and phosphorus element are calculated based on the molar amounts of their oxides.

[0025] In a preferred embodiment, the promoter element is derived from a compound containing the promoter element. Preferably, the compound containing the promoter element is selected from at least one (e.g., at least two, at least three, or at least four) of magnesium-containing compounds, calcium-containing compounds, strontium-containing compounds, copper-containing compounds, zinc-containing compounds, silver-containing compounds, iron-containing compounds, bismuth-containing compounds, cobalt-containing compounds, zirconium-containing compounds, niobium-containing compounds, and tungsten-containing compounds.

[0026] In a preferred embodiment, the promoter element I is derived from a compound containing the promoter element I.

[0027] In a further preferred embodiment, in the promoter element I, the magnesium element, calcium element, and strontium element are respectively derived from a magnesium-containing compound, a calcium-containing compound, and a strontium-containing compound.

[0028] In a still further preferred embodiment, the magnesium-containing compound is selected from at least one of magnesium nitrate and magnesium chloride, and / or the calcium-containing compound is selected from at least one of calcium nitrate and calcium chloride, and / or the strontium-containing compound is selected from at least one of strontium nitrate and strontium chloride.

[0029] In a preferred embodiment, the promoter element II is derived from a compound containing the promoter element II.

[0030] In a further preferred embodiment, in the promoter element II, the copper, zinc, and silver elements are respectively derived from a copper-containing compound, a zinc-containing compound, and a silver-containing compound.

[0031] In a still further preferred embodiment, the copper-containing compound is selected from at least one of copper nitrate, copper chloride, and copper sulfate, the zinc-containing compound is selected from at least one of zinc nitrate, zinc chloride, and zinc sulfate, and the silver-containing compound is selected from at least one of silver nitrate and silver chloride.

[0032] In a preferred embodiment, the promoter element III is derived from a compound containing the promoter element III.

[0033] In a further preferred embodiment, in the promoter element III, the iron, bismuth, and cobalt elements are respectively derived from an iron-containing compound, a bismuth-containing compound, and a cobalt-containing compound.

[0034] In a still further preferred embodiment, the iron-containing compound is selected from at least one of iron nitrate, iron chloride, and iron sulfate, the bismuth-containing compound is selected from at least one of bismuth nitrate and bismuth acetate, and the cobalt-containing compound is selected from at least one of cobalt nitrate, cobalt chloride, and cobalt sulfate.

[0035] In a preferred embodiment, the promoter element IV is derived from a compound containing the promoter element IV.

[0036] In a further preferred embodiment, in the promoter element IV, the zirconium, niobium, and tungsten elements are respectively derived from a zirconium-containing compound, a niobium-containing compound, and a tungsten-containing compound.

[0037] In an even more preferred embodiment, the zirconium-containing compound is selected from at least one of zirconium nitrate, zirconium chloride, and zirconium sulfate; the niobium-containing compound is selected from at least one of niobium nitrate, niobium oxalate, and niobium pentachloride; and the tungsten-containing compound is selected from at least one of tungsten nitrate, tungsten chloride, and tungsten sulfate.

[0038] In a preferred embodiment, based on 100 wt% of the catalyst, the active component accounts for 8 - 20 wt%, and the carrier accounts for 80 - 92 wt%.

[0039] For example, based on 100 wt% of the catalyst, the active component accounts for 8 wt%, 10 wt%, 12 wt%, 14 wt%, 16 wt%, 18 wt%, or 20 wt%, and the carrier accounts for 80 wt%, 82 wt%, 84 wt%, 86 wt%, 88 wt%, 90 wt%, or 92 wt%.

[0040] Among them, if the loading amount of the active component is insufficient, that is, the loading of the active component is too low, it may lead to problems such as low activity of the catalyst and low fluorene conversion rate; while if the loading of the active component is too high, deep oxidation is serious, there are more by-products, and the selectivity of 9-fluorenone decreases.

[0041] In a preferred embodiment, the molar ratio of titanium element to vanadium element is 1:(0.005 - 0.5), the molar ratio of titanium element to potassium element is 1:(0.001 - 0.2), the molar ratio of titanium element to nickel element is 1:(0.0001 - 0.05), and the molar ratio of titanium element to the promoter element is 1:(0.0001 - 0.05), where the molar amounts of titanium element, vanadium element, potassium element, and nickel element are calculated based on the molar amounts of their oxides, and the molar amounts of the promoter elements are calculated based on the molar amounts of their elements respectively.

[0042] For example, the molar ratio of titanium element to vanadium element is 1:0.005, 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.08, 1:0.1, 1:0.2, 1:0.3, 1:0.4 or 1:0.5; the molar ratio of titanium element to potassium element is 1:0.001, 1:0.005, 1:0.01, 1:0.05, 1:0.1, 1:0.15 or 1:0.2; the molar ratio of titanium element to nickel element is 1:0.0001, 1:0.0005, 1:0.001, 1:0.005, 1:0.01, 1:0.02, 1:0.04 or 1:0.05; and the molar ratio of titanium element to promoter element is 1:0.0001, 1:0.0005, 1:0.001, 1:0.005, 1:0.01, 1:0.02, 1:0.04 or 1:0.05.

[0043] In a further preferred embodiment, the molar ratio of titanium element to promoter element I is 1:(0.0005 - 0.02), the molar ratio of titanium element to promoter element II is 1:(0.0005 - 0.02), the molar ratio of titanium element to promoter element III is 1:(0.0001 - 0.03), and the molar ratio of titanium element to promoter element IV is 1:(0.0001 - 0.05), wherein the molar amounts of titanium element, vanadium element, potassium element, and nickel element are calculated based on the molar amounts of their oxides, and the molar amounts of promoter element I, promoter element II, promoter element III, and promoter element IV are calculated based on the molar amounts of their elements respectively.

[0044] For example, the molar ratio of titanium element to promoter element I is 1:0.0005, 1:0.008, 1:0.001, 1:0.002, 1:0.005, 1:0.008, 1:0.01, 1:0.012, 1:0.015, 1:0.018 or 1:0.02; the molar ratio of titanium element to promoter element II is 1:0.0005, 1:0.0008, 1:0.001, 1:0.002, 1:0.005, 1:0.008, 1:0.01, 1:0.012, 1:0.015, 1:0.018 or 1:0.02; the molar ratio of titanium element to promoter element III is 1:0.0001, 1:0.0002, 1:0.0005, 1:0.0008, 1:0.001, 1:0.002, 1:0.005, 1:0.008, 1:0.01, 1:0.02 or 1:0.03; the molar ratio of titanium element to promoter element IV is 1:0.0001, 1:0.0002, 1:0.0005, 1:0.0008, 1:0.001, 1:0.002, 1:0.005, 1:0.008, 1:0.01, 1:0.02, 1:0.03, 1:0.04 or 1:0.05. Among them, the molar amounts of titanium element, vanadium element, potassium element and nickel element are calculated based on the molar amounts of their oxides, and the molar amounts of promoter element I, promoter element II, promoter element III and promoter element IV are calculated based on the molar amounts of their elements respectively.

[0045] The second object of the present invention is to provide a preparation method of a catalyst for the selective oxidation of fluorene to prepare 9-fluorenone, preferably used for preparing the catalyst described in the first object of the present invention. The preparation method includes: first mixing a mixture containing active components with a reducing agent to obtain an active slurry mixture, then loading the active slurry mixture onto the carrier to obtain a catalyst precursor, and finally performing an activation treatment on the catalyst precursor to obtain the catalyst.

[0046] In a preferred embodiment, the mixture containing active components is obtained as follows: adding component sources including a titanium-containing compound, a vanadium-containing compound, a potassium-containing compound, a nickel-containing compound, and a compound containing a promoter element to a reducing agent to obtain the active slurry mixture.

[0047] Preferably, the compound containing a promoter element is selected from the mixture of a compound containing promoter element I, a compound containing promoter element II, a compound containing promoter element III, and a compound containing promoter element IV

[0048] In a further preferred embodiment, the mixture containing the active components is obtained as follows: A titanium-containing compound, a vanadium-containing compound, a potassium-containing compound, a nickel-containing compound, a compound containing promoter element I, a compound containing promoter element II, a compound containing promoter element III, and a compound containing promoter element IV are added to a reducing agent to obtain the active slurry mixture.

[0049] Wherein, when the titanium-containing compound is selected from titanium dioxide, it is first ball-milled and then mixed with other substances.

[0050] In a preferred embodiment, the molar ratio of the titanium-containing compound to the vanadium-containing compound is 1:(0.005 - 0.5), the molar ratio of the titanium-containing compound to the potassium-containing compound is 1:(0.001 - 0.2), the molar ratio of the titanium-containing compound to the nickel-containing compound is 1:(0.0001 - 0.05), and the molar ratio of the titanium-containing compound to the compound containing the promoter element is 1:(0.0001 - 0.05). Among them, the molar amounts of the titanium-containing compound, the vanadium-containing compound, the potassium-containing compound, and the nickel-containing compound are calculated based on the molar amounts of their oxides, and the molar amounts of the compounds containing the promoter element are calculated based on the molar amounts of their promoter elements respectively.

[0051] In a further preferred embodiment, the molar ratio of the titanium-containing compound to the compound containing promoter element I is 1:(0.0005 - 0.02), the molar ratio of the titanium-containing compound to the compound containing promoter element II is 1:(0.0005 - 0.02), the molar ratio of the titanium-containing compound to the compound containing promoter element III is 1:(0.0001 - 0.03), and the molar ratio of the titanium-containing compound to the compound containing promoter element IV is 1:(0.0001 - 0.05). Among them, the molar amount of the titanium-containing compound is calculated based on the molar amount of its oxide, and the molar amounts of the compounds containing promoter element I, promoter element II, promoter element III, and promoter element IV are calculated based on the molar amounts of their elements respectively.

[0052] In a preferred embodiment, the component source further includes a phosphorus-containing compound.

[0053] In a further preferred embodiment, the phosphorus-containing compound is selected from at least one of trisodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, pyrophosphoric acid, potassium phosphate, dipotassium hydrogen phosphate, and potassium dihydrogen phosphate.

[0054] In an even more preferred embodiment, the molar ratio of the titanium-containing compound to the phosphorus-containing compound is 1:(0.0001 - 0.05). Among them, the molar amounts of the titanium-containing compound and the vanadium-containing compound are calculated based on the molar amounts of their oxides, and the molar amount of the phosphorus-containing compound is calculated based on the molar amount of its element.

[0055] In a preferred embodiment, the reducing agent is selected from at least one of oxalic acid and ammonium hydrogen oxalate.

[0056] In a further preferred embodiment, the molar ratio of the reducing agent to the titanium-containing compound is 0.05 - 0.3, such as 0.05, 0.1, 0.15, 0.2, 0.25 or 0.3.

[0057] In a preferred embodiment, the loading is carried out by spraying.

[0058] In a further preferred embodiment, the loading is carried out under the spraying conditions disclosed in the prior art. Preferably but not limited to, the loading includes: adjusting the rotating drum speed to 15 - 40 revolutions per minute (such as 15 revolutions per minute, 20 revolutions per minute, 25 revolutions per minute, 30 revolutions per minute, 35 revolutions per minute or 40 revolutions per minute), first heating the carrier to 150 - 300 °C (such as 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, 240 °C, 260 °C, 280 °C or 300 °C), then spraying the active slurry mixture onto the carrier, wherein the spraying temperature is 200 - 300 °C (such as 200 °C, 220 °C, 240 °C, 260 °C, 280 °C or 300 °C), and maintaining the carrier temperature between 230 - 290 °C (such as 230 °C, 240 °C, 250 °C, 260 °C, 270 °C, 280 °C or 290 °C). After spraying, drying is carried out to obtain the catalyst precursor.

[0059] In a still further preferred embodiment, the loading is carried out as follows: adjusting the rotating drum speed to 15 - 35 revolutions per minute, first heating the carrier to 180 - 250 °C, then spraying the active slurry mixture onto the carrier, wherein the spraying temperature is 240 - 280 °C, and maintaining the carrier temperature between 260 - 270 °C. After spraying, drying is carried out to obtain the catalyst precursor.

[0060] In a preferred embodiment, the activation treatment adopts any activation treatment method disclosed in the prior art. Preferably but not limited to, the activation treatment is carried out as follows: (First, the catalyst precursor) (1) is heated from room temperature to 120 - 180 °C (such as 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C or 180 °C) and kept warm; (2) heated to 220 - 280 °C (such as 220 °C, 230 °C, 240 °C, 250 °C, 260 °C, 270 °C or 280 °C) and kept warm; (3) heated to 320 - 380 °C (320 °C, 330 °C, 340 °C, 350 °C, 360 °C, 370 °C or 380 °C) and kept warm; (4) heated to 450 - 500 °C (such as 450 °C, 460 °C, 470 °C, 480 °C, 490 °C or 500 °C) and kept warm; (5) cooled to room temperature.

[0061] In a further preferred embodiment, the activation treatment adopts any activation treatment method disclosed in the prior art. Preferably but not limited to, the activation treatment includes: (The catalyst precursor) (1) is heated from room temperature to 120 - 180 °C at a rate of 60 - 120 °C / h (such as 60 °C / h, 70 °C / h, 80 °C / h, 90 °C / h, 100 °C / h, 110 °C / h or 120 °C / h) and kept for 5 - 30 minutes (such as 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes or 30 minutes); (2) heated to 220 - 280 °C at a heating rate of 50 - 110 °C / h (such as 50 °C / h, 60 °C / h, 70 °C / h, 80 °C / h, 90 °C / h, 100 °C / h or 110 °C / h) and kept for 5 - 30 minutes (such as 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes or 30 minutes); (3) heated to 320 - 380 °C at a heating rate of 40 - 100 °C / h (such as 40 °C / h, 50 °C / h, 60 °C / h, 70 °C / h, 80 °C / h, 90 °C / h or 100 °C / h) and kept for 10 - 60 minutes (such as 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes or 60 minutes); (4) heated to 450 - 500 °C at a heating rate of 30 - 90 °C / h (such as 30 °C / h, 40 °C / h, 50 °C / h, 60 °C / h, 70 °C / h, 80 °C / h or 90 °C / h) and maintained for 5 - 10 hours (5 hours, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours); (5) cooled to room temperature.

[0062] In a still further preferred embodiment, the activation is carried out in an anaerobic environment, preferably in a sealed environment with nitrogen and / or helium.

[0063] Among them, the catalyst is activated in a closed container. The closed container is a cylindrical or cubic activation furnace body. The upper part of the furnace body is sealed by a flange to isolate the internal space from the outside. The outer wall of the furnace body is wound with electric heating wires, and a heat-insulating cloth or heat-insulating tile is provided outside the electric heating wires. The heating temperature of the furnace body is controlled by an automatic digital temperature control meter; ventilation openings are provided at the upper and lower parts of the furnace body. The lower ventilation opening serves as the gas inlet, and the upper ventilation opening serves as the gas outlet. The gas flow rate is controlled by a gas mass flow meter.

[0064] The third object of the present invention is to provide the application of the catalyst described in the first object of the present invention or the catalyst obtained by using the preparation method described in the second object of the present invention in the selective oxidation of fluorene to prepare 9-fluorenone.

[0065] The fourth object of the present invention is to provide a method for the selective oxidation of fluorene to prepare 9-fluorenone, including: preparing 9-fluorenone from a mixed gas of fluorene and air in the presence of the catalyst described in the first object of the present invention or the catalyst obtained by using the preparation method described in the second object of the present invention.

[0066] Among them, 9-fluorenone is prepared by oxidizing a mixed gas of fluorene and air through a fixed-bed reactor filled with the catalyst.

[0067] In a preferred embodiment, the concentration of fluorene in the mixed gas is 40-55 g / Nm 3 , for example, 40 g / Nm 3 , 45 g / Nm 3 , 50 g / Nm 3 or 55 g / Nm 3 .

[0068] In a preferred embodiment, the volume space velocity of the mixed gas is 1500-3500 h -1 , for example, 1500 h -1 , 2000 h -1 , 2500 h -1 , 3000 h -1 or 3500 h -1 .

[0069] In a further preferred embodiment, the volume space velocity of the mixed gas is 1500-2500 h -1 .

[0070] In a preferred embodiment, a molten salt bath is used for heating and removing heat.

[0071] In a further preferred embodiment, the temperature of the molten salt is 350-410 °C, for example, 350 °C, 360 °C, 370 °C, 380 °C, 390 °C, 400 °C or 410 °C.

[0072] In a preferred embodiment, the reaction pressure is negative pressure, atmospheric pressure, or positive pressure, preferably atmospheric pressure.

[0073] Among them, the process of preparing 9-fluorenone uses a fixed-bed reactor and a molten salt bath for heating and heat removal. During the evaluation of the reaction process, the temperatures at various positions from top to bottom in the catalyst bed are inconsistent. The highest value in the temperature region is called the hot spot temperature of the catalyst, and the corresponding bed height is the hot spot position of the catalyst. In the present invention, a thermocouple is used to measure the temperature by pulling the bed layer. The fluorene concentration refers to the mass number of fluorene contained in unit volume of air, measured in grams. The higher the value, the higher the content of fluorene in the air.

[0074] In the ranges and any values disclosed in the present invention, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein. In the following text, in principle, various technical solutions can be combined with each other to obtain new technical solutions, which should also be regarded as specifically disclosed herein.

[0075] Compared with the prior art, the present invention has the following beneficial effects:

[0076] (1) Using the carrier prepared by the present invention, the raw materials are easily available, the preparation process is simple, the conditions are easy to control. By introducing different types of metal promoters for compounding, the reaction activity of the catalyst is improved, thereby reducing the molten salt temperature.

[0077] (2) Using the catalyst prepared by the present invention, a gas-solid phase reaction is adopted, which is conducive to the continuous selective oxidation of fluorene to prepare 9-fluorenone and is easy for large-scale production.

[0078] (3) Using the catalyst prepared by the present invention, the use of a large amount of solvents and the problem of emulsified wastewater can be avoided, which is beneficial to environmental protection.

[0079] (4) Using the catalyst prepared by the present invention, the use of phase transfer catalysts can be reduced, and at the same time, the use of strongly corrosive sodium hydroxide, etc., can be avoided, reducing environmental pollution. Specific Embodiments

[0080] The present invention will be specifically described below in conjunction with specific embodiments. It is necessary to point out here that the following embodiments are only for further illustration of the present invention and cannot be understood as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.

[0081] In addition, it should be noted that the various specific technical features described in the following specific embodiments can be combined in any appropriate manner without contradiction. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0082] In addition, any combination can be made between various different embodiments of the present invention as long as it does not violate the idea of the present invention. The technical solutions thus formed belong to a part of the original public content of this specification and also fall within the protection scope of the present invention.

[0083] If there is no special limitation on the raw materials used in the examples and comparative examples, they are all disclosed in the prior art. For example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art. In the following quantitative tests of the examples, three repeated experiments are set, and the results are averaged.

[0084]

Example 1

[0085] Step A: Dissolve 15 g of oxalic acid in 300 mL of water at room temperature, add 7.6 g of ammonium metavanadate, and add it while stirring until the ammonium metavanadate is dissolved to form a homogeneous and stable solution. Then, sequentially add 2.1 g of potassium hydroxide, 1.4 g of dipotassium hydrogen phosphate, 1.2 g of nickel nitrate, 0.5 g of magnesium nitrate, 0.4 g of copper nitrate, 0.6 g of iron nitrate, and 0.7 g of zirconium nitrate while stirring. Mix the above solution with 87.8 g of TiO2, and then perform ball milling for 4 hours to obtain a catalyst active mother liquor. Step B: Take 400 g of silicon carbide powder, add 20 g of magnesium oxide, 25 g of methyl cellulose, and 20 g of diatomaceous earth, add 90 ml of water, and mix, stir, and knead to form a ring-shaped carrier. Dry it at 120 °C for 12 hours and calcine it at 1000 °C for 5 hours.

[0086] Put 320 g of the above carrier into a rotatable and heatable stainless steel drum. A thermocouple sleeve is provided at the bottom of the carrier, and the internal thermocouple is connected to a temperature display instrument to display the temperature change during the spraying process in real time. Adjust the drum rotation speed to 20 revolutions per minute. When the carrier temperature is heated to 250 °C, spray the above active slurry mixture onto the carrier through a special nozzle. The spraying temperature is 250 - 300 °C (temperature measurement), and keep the carrier temperature between 260 - 270 °C (temperature measurement). After spraying, dry the catalyst precursor at 120 °C for 4 hours, and weigh to obtain 360 g of the catalyst precursor. Calculated by the total mass of the catalyst, the content of the active substance is 11.1%.

[0087] Step C: Place 150 g of the above catalyst precursor in an activation furnace. After sealing, raise the temperature from room temperature to 150 °C at a heating rate of 120 °C / h and hold for 5 minutes. Subsequently, raise the temperature to 250 °C at a heating rate of 110 °C / h and hold for 10 minutes. Then, raise the temperature to 350 °C at a heating rate of 100 °C / h and hold at 350 °C for 20 minutes. Then, raise the temperature to 480 °C at a heating rate of 90 °C / h and hold at this temperature for 5 hours. Subsequently, gradually lower the temperature to room temperature to obtain Catalyst A.

[0088] Load Catalyst A into the fixed-bed reactor for testing. Use a molten salt temperature of 365 °C. The results are shown in Table 1.

[0089]

Example 2

[0090] Step A: Dissolve 15 g of oxalic acid in 300 mL of water at room temperature. Add 7.6 g of ammonium metavanadate while stirring until the ammonium metavanadate dissolves to form a homogeneous and stable solution. While stirring, sequentially add 2.1 g of potassium hydroxide, 1.4 g of dipotassium hydrogen phosphate, 1.2 g of nickel nitrate, 0.5 g of magnesium nitrate, 1.4 g of copper nitrate, 0.6 g of iron nitrate, and 0.7 g of zirconium nitrate. Mix the above solution with 87.8 g of TiO2, and then ball-mill for 4 hours to obtain the catalyst active mother liquor.

[0091] Step B: Take 400 g of silicon carbide powder, and then add 15 g of magnesium oxide, 25 g of methyl cellulose, and 20 g of diatomite. Add 90 ml of water, mix, stir, and knead into an annular carrier. Dry at 120 °C for 12 hours and calcine at 1100 °C for 5 hours.

[0092] Take 320 g of the above carrier and place it in a rotatable and heatable stainless-steel drum. A thermocouple sleeve is provided at the bottom of the carrier, and the internal thermocouple is connected to a temperature display instrument to real-time display the temperature change during the spraying process. Adjust the drum rotation speed to 20 revolutions per minute. When the carrier temperature is heated to 250 °C, spray the above active slurry mixture onto the carrier through a special nozzle. The spraying temperature is 250 - 300 °C (temperature measurement), and keep the carrier temperature between 260 - 270 °C (temperature measurement). After spraying, dry the catalyst precursor at 120 °C for 4 hours, and weigh to obtain 361 g of the catalyst precursor. Calculated based on the total mass of the catalyst, the content of the active substance is 11.4%.

[0093] Step C: Place 150 g of the above catalyst precursor in an activation furnace. After sealing, raise the temperature from room temperature to 150 °C at a heating rate of 120 °C / h and hold for 5 minutes. Then, raise the temperature to 250 °C at a heating rate of 110 °C / h and hold for 10 minutes. Next, raise the temperature to 350 °C at a heating rate of 100 °C / h and hold at 350 °C for 20 minutes. Then, raise the temperature to 500 °C at a heating rate of 90 °C / h and hold at this temperature for 5 hours. Subsequently, gradually lower the temperature to room temperature to obtain catalyst B.

[0094] Load catalyst B into the fixed-bed reactor for testing. Use a molten salt temperature of 365 °C. The results are shown in Table 1.

[0095]

Example 3

[0096] Step A: Dissolve 15 g of oxalic acid in 300 mL of water at room temperature. Add 7.6 g of ammonium metavanadate while stirring until it dissolves to form a homogeneous and stable solution. Then, sequentially add 4.2 g of potassium hydroxide, 1.4 g of dipotassium hydrogen phosphate, 1.2 g of nickel nitrate, 0.5 g of magnesium nitrate, 0.4 g of copper nitrate, 1.6 g of iron nitrate, and 0.7 g of zirconium nitrate while stirring. Mix the above solution with 87.8 g of TiO2, and then ball-mill for 4 hours to obtain the catalyst active mother liquor.

[0097] Step B: Take 400 g of silicon carbide powder, add 20 g of magnesium oxide, 25 g of methyl cellulose, and 15 g of diatomaceous earth. Add 90 ml of water and mix, stir, and knead into a ring-shaped carrier. Dry at 120 °C for 12 hours and calcine at 1000 °C for 5 hours.

[0098] Take 330 g of the above carrier and place it in a rotatable and heatable stainless-steel drum. A thermocouple sleeve is provided at the bottom of the carrier, and the internal thermocouple is connected to a temperature display instrument to display the temperature change during the spraying process in real time. Adjust the drum rotation speed to 240 revolutions per minute. When the carrier temperature is heated to 250 °C, spray the above active slurry mixture onto the carrier through a special nozzle. The spraying temperature is 250 - 300 °C (temperature measurement), and keep the carrier temperature between 260 - 270 °C (temperature measurement). After spraying, dry the catalyst precursor at 120 °C for 4 hours and weigh to obtain 370 g of the catalyst precursor. Calculated based on the total mass of the catalyst, the content of the active substance is 10.8%.

[0099] Step C: Place 150 g of the above catalyst precursor in an activation furnace. After sealing, raise the temperature from room temperature to 150 °C at a heating rate of 120 °C / h and hold for 5 minutes. Then raise the temperature to 250 °C at a heating rate of 110 °C / h and hold for 10 minutes. Next, raise the temperature to 350 °C at a heating rate of 100 °C / h and hold at 350 °C for 20 minutes. Then raise the temperature to 490 °C at a heating rate of 90 °C / h and hold at this temperature for 5 hours. Subsequently, gradually lower the temperature to room temperature to obtain catalyst C.

[0100] Load catalyst C into the fixed-bed reactor for testing. Use a molten salt temperature of 365 °C. The results are shown in Table 1.

[0101]

Example 4

[0102] Step A: Dissolve 15 g of oxalic acid in 300 mL of water at room temperature. Add 7.6 g of ammonium metavanadate while stirring until it dissolves to form a homogeneous and stable solution. Then, while stirring, sequentially add 2.1 g of potassium hydroxide, 1.4 g of dipotassium hydrogen phosphate, 1.2 g of nickel nitrate, 0.5 g of magnesium nitrate, 0.4 g of copper nitrate, 0.6 g of iron nitrate, and 1.7 g of zirconium nitrate. Mix the above solution with 87.8 g of TiO2 and then ball-mill for 4 hours to obtain the catalyst active mother liquor.

[0103] Step B: Take 400 g of silicon carbide powder, add 20 g of magnesium oxide, 25 g of methyl cellulose, and 20 g of diatomite. Add 90 ml of water and mix, stir, and knead into a ring-shaped carrier. Dry at 120 °C for 12 hours and calcine at 1000 °C for 5 hours.

[0104] Take 330 g of the above carrier and place it in a rotatable and heatable stainless steel drum. A thermocouple sleeve is provided at the bottom of the carrier, and the internal thermocouple is connected to a temperature display instrument to display the temperature change during the spraying process in real time. Adjust the drum rotation speed to 20 revolutions per minute. When the carrier temperature is heated to 250 °C, spray the above active slurry mixture onto the carrier through a special nozzle. The spraying temperature is 250 - 300 °C (temperature measurement), and keep the carrier temperature between 260 - 270 °C (temperature measurement). After spraying, dry the catalyst precursor at 120 °C for 4 hours and weigh to obtain 372 g of the catalyst precursor. Calculated based on the total mass of the catalyst, the content of the active substance is 11.3%.

[0105] Step C: Place 150 g of the above catalyst precursor in an activation furnace. After sealing, raise the temperature from room temperature to 150 °C at a heating rate of 120 °C / h and hold for 5 minutes. Then raise the temperature to 250 °C at a heating rate of 110 °C / h and hold for 10 minutes. Next, raise the temperature to 350 °C at a heating rate of 100 °C / h and hold at 350 °C for 20 minutes. Then raise the temperature to 500 °C at a heating rate of 90 °C / h and hold at this temperature for 5 hours. Subsequently, gradually lower the temperature to room temperature to obtain catalyst D.

[0106] Load catalyst D into the fixed-bed reactor for testing. Use a molten salt temperature of 365 °C. The results are shown in Table 1.

[0107]

Example 5

[0108] Step A: Dissolve 15 g of oxalic acid in 300 mL of water at room temperature. Add 7.6 g of ammonium metavanadate while stirring until it dissolves to form a homogeneous and stable solution. While stirring, sequentially add 2.1 g of potassium hydroxide, 1.4 g of dipotassium hydrogen phosphate, 1.2 g of nickel nitrate, 2.5 g of magnesium nitrate, 0.4 g of copper nitrate, 0.6 g of iron nitrate, and 0.7 g of zirconium nitrate. Mix the above solution with 87.8 g of TiO2 and then ball-mill for 4 hours to obtain the catalyst active mother liquor.

[0109] Step B: Take 400 g of silicon carbide powder, add 20 g of magnesium oxide, 25 g of methyl cellulose, and 20 g of diatomite. Add 90 ml of water, mix, stir, and knead into a ring-shaped carrier. Dry at 120 °C for 12 hours and calcine at 1000 °C for 5 hours.

[0110] Take 320 g of the above carrier and place it in a rotatable and heatable stainless steel drum. A thermocouple sleeve is provided at the bottom of the carrier, and the internal thermocouple is connected to a temperature display instrument to real-time display the temperature change during the spraying process. Adjust the drum rotation speed to 20 revolutions per minute. When the carrier temperature is heated to 250 °C, spray the above active slurry mixture onto the carrier through a special nozzle. The spraying temperature is 250 - 300 °C (temperature measurement), and keep the carrier temperature between 260 - 270 °C (temperature measurement). After spraying, dry the catalyst precursor at 120 °C for 4 hours and weigh to obtain 359 g of the catalyst precursor. Based on the total mass of the catalyst, the content of the active substance is 10.8%.

[0111] Step C: Place 150 g of the above catalyst precursor in an activation furnace. After sealing, raise the temperature from room temperature to 150 °C at a heating rate of 120 °C / h and hold for 5 minutes. Then, raise the temperature to 250 °C at a heating rate of 110 °C / h and hold for 10 minutes. Next, raise the temperature to 350 °C at a heating rate of 100 °C / h and hold at 350 °C for 20 minutes. Then, raise the temperature to 490 °C at a heating rate of 90 °C / h and hold at this temperature for 5 hours. Subsequently, gradually lower the temperature to room temperature to obtain catalyst E.

[0112] Load catalyst E into the fixed-bed reactor for testing. Use a molten salt temperature of 365 °C. The results are shown in Table 1.

[0113]

Example 6

[0114] Step A: Dissolve 15 g of oxalic acid in 300 mL of water at room temperature. Add 7.6 g of ammonium metavanadate while stirring until it dissolves to form a homogeneous and stable solution. Then, sequentially add 2.1 g of potassium hydroxide, 1.4 g of dipotassium hydrogen phosphate, 1.2 g of nickel nitrate, 0.5 g of calcium nitrate, 0.4 g of copper nitrate, 0.6 g of iron nitrate, and 0.7 g of zirconium nitrate while stirring. Mix the above solution with 87.8 g of TiO2 and then ball mill for 4 hours to obtain the catalyst active mother liquor.

[0115] Step B: Take 400 g of silicon carbide powder, add 20 g of magnesium oxide, 25 g of methyl cellulose, and 20 g of diatomaceous earth. Add 90 ml of water and mix, stir, and knead into a ring-shaped carrier. Dry at 120 °C for 12 hours and calcine at 1000 °C for 5 hours.

[0116] Take 320 g of the above carrier and place it in a rotatable and heatable stainless steel drum. A thermocouple sleeve is provided at the bottom of the carrier, and the internal thermocouple is connected to a temperature display instrument to display the temperature change during the spraying process in real time. Adjust the drum rotation speed to 20 revolutions per minute. When the carrier temperature is heated to 250 °C, spray the above active slurry mixture onto the carrier through a special nozzle. The spraying temperature is 250 - 300 °C (temperature measurement), and keep the carrier temperature between 260 - 270 °C (temperature measurement). After spraying, dry the catalyst precursor at 120 °C for 4 hours and weigh to obtain 361 g of the catalyst precursor. Calculated based on the total mass of the catalyst, the content of the active substance is 11.4%.

[0117] Step C: Place 150 g of the above catalyst precursor in an activation furnace. After sealing, raise the temperature from room temperature to 150 °C at a heating rate of 120 °C / h and hold for 5 minutes. Then, raise the temperature to 250 °C at a heating rate of 110 °C / h and hold for 10 minutes. Next, raise the temperature to 350 °C at a heating rate of 100 °C / h and hold at 350 °C for 20 minutes. Then, raise the temperature to 480 °C at a heating rate of 90 °C / h and hold at this temperature for 5 hours. Subsequently, gradually lower the temperature to room temperature to obtain catalyst F.

[0118] Load catalyst F into the fixed-bed reactor for testing. Use a molten salt temperature of 365 °C. The results are shown in Table 1.

[0119]

Example 7

[0120] Step A: Dissolve 15 g of oxalic acid in 300 mL of water at room temperature. Add 7.6 g of ammonium metavanadate while stirring until it dissolves to form a homogeneous and stable solution. While stirring, sequentially add 2.1 g of potassium hydroxide, 1.4 g of dipotassium hydrogen phosphate, 1.2 g of nickel nitrate, 0.5 g of calcium nitrate, 0.4 g of zinc nitrate, 0.6 g of iron nitrate, and 0.7 g of zirconium nitrate. Mix the above solution with 87.8 g of TiO2 and then ball-mill for 4 hours to obtain the catalyst active mother liquor.

[0121] Step B: Take 400 g of silicon carbide powder, add 20 g of magnesium oxide, 25 g of methylcellulose, and 20 g of diatomite. Add 90 ml of water, mix, stir, and knead into a ring-shaped carrier. Dry at 120 °C for 12 hours and calcine at 1000 °C for 5 hours.

[0122] Take 320 g of the above carrier and place it in a rotatable and heatable stainless-steel drum. A thermocouple sleeve is provided at the bottom of the carrier, and the internal thermocouple is connected to a temperature display instrument to display the temperature change during the spraying process in real time. Adjust the drum rotation speed to 20 revolutions per minute. When the carrier temperature is heated to 250 °C, spray the above active slurry mixture onto the carrier through a special nozzle. The spraying temperature is 250 - 300 °C (temperature measurement), and keep the carrier temperature between 260 - 270 °C (temperature measurement). After spraying, dry the catalyst precursor at 120 °C for 4 hours and weigh to obtain 361 g of the catalyst precursor. Calculated based on the total mass of the catalyst, the content of the active substance is 11.4%.

[0123] Step C: Place 150 g of the above catalyst precursor in an activation furnace. After sealing, raise the temperature from room temperature to 150 °C at a heating rate of 120 °C / h and hold for 5 minutes. Subsequently, raise the temperature to 250 °C at a heating rate of 110 °C / h and hold for 10 minutes. Then, raise the temperature to 350 °C at a heating rate of 100 °C / h and hold at 350 °C for 20 minutes. Then, raise the temperature to 480 °C at a heating rate of 90 °C / h and hold at this temperature for 5 hours. Subsequently, gradually lower the temperature to room temperature to obtain catalyst G.

[0124] Load catalyst G into the fixed-bed reactor for testing. Use a molten salt temperature of 365 °C. The results are shown in Table 1.

[0125]

Example 8

[0126] Step A: Dissolve 15 g of oxalic acid in 300 mL of water at room temperature. Add 7.6 g of ammonium metavanadate while stirring until the ammonium metavanadate dissolves to form a homogeneous and stable solution. While stirring, sequentially add 2.1 g of potassium hydroxide, 1.4 g of dipotassium hydrogen phosphate, 1.2 g of nickel nitrate, 0.5 g of calcium nitrate, 0.4 g of zinc nitrate, 0.6 g of cobalt nitrate, and 0.7 g of tungsten nitrate. Mix the above solution with 87.8 g of TiO2, and then ball-mill for 4 hours to obtain the catalyst active mother liquor.

[0127] Step B: Take 400 g of silicon carbide powder, and then add 20 g of magnesium oxide, 25 g of methyl cellulose, and 20 g of diatomite. Add 90 ml of water, mix, stir, and knead into a ring-shaped carrier. Dry at 120 °C for 12 hours and calcine at 1000 °C for 5 hours.

[0128] Take 320 g of the above carrier and place it in a rotatable and heatable stainless-steel drum. A thermocouple sleeve is provided at the bottom of the carrier, and the internal thermocouple is connected to a temperature display instrument to display the temperature change during the spraying process in real time. Adjust the drum rotation speed to 20 revolutions per minute. When the carrier temperature is heated to 250 °C, spray the above active slurry mixture onto the carrier through a special nozzle. The spraying temperature is 250 - 300 °C (temperature measurement), and keep the carrier temperature between 260 - 270 °C (temperature measurement). After spraying, dry the catalyst precursor at 120 °C for 4 hours, and weigh to obtain 361 g of the catalyst precursor. Calculated based on the total mass of the catalyst, the content of the active substance is 11.4%.

[0129] Step C: Place 150 g of the above catalyst precursor in an activation furnace. After sealing, increase the temperature from room temperature to 150 °C at a heating rate of 120 °C / h and hold for 5 minutes. Subsequently, increase the temperature to 250 °C at a heating rate of 110 °C / h and hold for 10 minutes. Then, increase the temperature to 350 °C at a heating rate of 100 °C / h and hold at 350 °C for 20 minutes. Then, increase the temperature to 480 °C at a heating rate of 90 °C / h and hold at this temperature for 5 hours. Subsequently, gradually decrease the temperature to room temperature to obtain catalyst H.

[0130] Load catalyst H into the fixed-bed reactor for testing. Use a molten salt temperature of 365 °C. The results are shown in Table 1.

[0131]

Comparative Example 1

[0132] Prepare catalyst I according to the same method as in Example 1, except that in step A: do not add magnesium nitrate. After spraying and drying, 359 g of catalyst precursor is obtained. Based on the total mass of the catalyst, the content of the active substance is 10.9%.

[0133] Load catalyst I into the fixed-bed reactor for testing. Use a molten salt temperature of 365 °C. The results are shown in Table 1.

[0134]

Comparative Example 2

[0135] Prepare catalyst J according to the same method as in Example 3, except that in step A: do not add copper nitrate. After spraying and drying, 369 g of catalyst precursor is obtained. Based on the total mass of the catalyst, the content of the active substance is 10.6%.

[0136] Load catalyst J into the fixed-bed reactor for testing. Use a molten salt temperature of 365 °C. The results are shown in Table 1.

[0137]

Comparative Example 3

[0138] Prepare catalyst K according to the same method as in Example 5, except that in step A: do not add iron nitrate. After spraying and drying, 358 g of catalyst precursor is obtained. Based on the total mass of the catalyst, the content of the active substance is 10.6%.

[0139] Load catalyst K into the fixed-bed reactor for testing. Use a molten salt temperature of 365 °C. The results are shown in Table 1.

[0140]

Comparative Example 4

[0141] Catalyst L was prepared in the same manner as in Example 5, except that in step A: zirconium nitrate was not added. After spraying and drying, 357 g of the catalyst precursor was obtained. Based on the total mass of the catalyst, the content of the active substance was 10.4%.

[0142] Catalyst L was loaded into the fixed-bed reactor for testing. The molten salt temperature was 365 °C, and the results are shown in Table 1.

[0143]

Comparative Example 5

[0144] Catalyst M was prepared in the same manner as in Example 1, except that in step A: magnesium nitrate and copper nitrate were not added. After spraying and drying, 358 g of the catalyst precursor was obtained. Based on the total mass of the catalyst, the content of the active substance was 10.6%.

[0145] Catalyst M was loaded into the fixed-bed reactor for testing. The molten salt temperature was 365 °C, and the results are shown in Table 1.

[0146]

Comparative Example 6

[0147] Catalyst N was prepared in the same manner as in Example 1, except that in step A: magnesium nitrate, copper nitrate, and iron nitrate were not added. After spraying and drying, 357 g of the catalyst precursor was obtained. Based on the total mass of the catalyst, the content of the active substance was 10.4%.

[0148] Catalyst N was loaded into the fixed-bed reactor for testing. The molten salt temperature was 365 °C, and the results are shown in Table 1.

[0149]

Comparative Example 7

[0150] Catalyst O was prepared in the same manner as in Example 1, except that in step A: magnesium nitrate, copper nitrate, iron nitrate, and zirconium nitrate were not added. After spraying and drying, 356 g of the catalyst precursor was obtained. Based on the total mass of the catalyst, the content of the active substance was 10.1%.

[0151] Catalyst O was loaded into the fixed-bed reactor for testing. The molten salt temperature was 365 °C, and the results are shown in Table 1.

[0152]

Comparative Example 8

[0153] Catalyst P was prepared in the same manner as in Example 1, except that in step A: ammonium molybdate of equal weight was used to replace TiO2, and other conditions remained unchanged.

[0154] Catalyst P was loaded into the fixed-bed reactor for testing. The molten salt temperature was 365 °C, and the results are shown in Table 1.

[0155] Catalyst Evaluation

[0156] Take the catalyst activated in the activation furnace and load it into the molten salt circulation reactor. There is an inert carrier at the bottom of the reactor for support, a certain volume of catalyst is filled in the middle, and an inert carrier of a certain height is installed at the upper part. When the molten salt is heated to the reaction temperature, air is supplied, fluorene is heated and fed into the reactor with the air. After the fluorene concentration reaches the required operating condition concentration, sampling and analysis are started after stabilizing for 1 hour. The sampling evaluation results of each catalyst are shown in Table 1. The calculation methods of each index are as follows:

[0157] Fluorene conversion rate (%) = (amount of substance of fluorene at the reactor inlet per unit time - amount of substance of fluorene at the reactor outlet per unit time) / amount of substance of fluorene at the reactor inlet per unit time × 100%;

[0158] Fluorene selectivity (%) = amount of substance of fluorene corresponding to the formation of 9-fluorenone / (amount of substance of fluorene at the reactor inlet per unit time - amount of substance of fluorene at the reactor outlet per unit time) × 100%.

[0159] Table 1 Evaluation results of the activity of the reaction tube

[0160]

[0161]

[0162] It can be seen from the above table that the technical solution of the present invention has the advantages of low hot spot temperature, high conversion rate and high selectivity.

[0163] The present invention has been described in detail above in combination with specific embodiments and exemplary examples, but these descriptions should not be construed as limiting the present invention. Those skilled in the art understand that without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications or improvements can be made to the technical solution of the present invention and its implementation manners, and these all fall within the scope of the present invention. The protection scope of the present invention is subject to the appended claims.

Claims

1. A catalyst for the selective oxidation of fluorene to prepare 9-fluorenone, characterized in that, The catalyst comprises a carrier and an active component. Among them, the active component includes vanadium element, titanium element, potassium element, nickel element and promoter element, and the promoter element is selected from at least one of magnesium element, calcium element, strontium element, copper element, zinc element, silver element, iron element, bismuth element, cobalt element, zirconium element, niobium element and tungsten element.

2. The catalyst according to claim 1, wherein The promoter element is selected from promoter element I, promoter element II, promoter element III and promoter element IV. The promoter element I is selected from at least one of magnesium element, calcium element and strontium element. The promoter element II is selected from at least one of copper element, zinc element and silver element. The promoter element III is selected from at least one of iron element, bismuth element and cobalt element. The promoter element IV is selected from at least one of zirconium element, niobium element and tungsten element.

3. The catalyst according to claim 1, characterized in that, The carrier is mainly composed of silicon carbide; preferably, based on 100 wt% of the carrier, the silicon carbide accounts for 65 - 92 wt%, preferably 70 - 90 wt%.

4. The catalyst according to claim 3, characterized in that, The carrier further contains an alkaline agent, a binder and a carrier pore regulator; Preferably, the alkaline agent is selected from at least one of magnesium oxide, sodium oxide and potassium oxide. The binder is selected from at least one of methyl cellulose and ethyl cellulose. The carrier pore regulator is selected from at least one of diatomite and zeolite powder; More preferably, based on 100 wt% of the carrier, the alkaline agent accounts for 1 - 12 wt%, the binder accounts for 5 - 12 wt%, and the carrier pore regulator accounts for 1 - 12 wt%.

5. The catalyst according to claim 1, wherein the vanadium element is derived from a vanadium-containing compound, and the vanadium-containing compound is selected from one or more of ammonium metavanadate, vanadium pentoxide and sodium vanadate; and / or, the titanium element is derived from a titanium-containing compound, and the titanium-containing compound is selected from one or more of titanium dioxide and titanium tetrachloride; and / or, the potassium element is derived from a potassium-containing compound, and the potassium-containing compound is selected from one or more of potassium hydroxide, potassium nitrate, potassium carbonate and potassium chloride; and / or, the nickel element is derived from a nickel-containing compound, and the nickel-containing compound is selected from one or more of nickel nitrate, nickel sulfate, nickel chloride and nickel oxide.

6. The catalyst according to claim 1, wherein The promoter element is derived from a compound containing the promoter element. Preferably, the compound containing the promoter element is selected from at least one of a magnesium-containing compound, a calcium-containing compound, a strontium-containing compound, a copper-containing compound, a zinc-containing compound, a silver-containing compound, an iron-containing compound, a bismuth-containing compound, a cobalt-containing compound, a zirconium-containing compound, a niobium-containing compound and a tungsten-containing compound.

7. The catalyst according to claim 2, wherein the promoter element I is derived from a compound containing the promoter element I; preferably, among the promoter element I, the magnesium element, the calcium element and the strontium element are respectively derived from a magnesium-containing compound, a calcium-containing compound and a strontium-containing compound; more preferably, the magnesium-containing compound is selected from at least one of magnesium nitrate and magnesium chloride, and / or, the calcium-containing compound is selected from at least one of calcium nitrate and calcium chloride, and / or, the strontium-containing compound is selected from at least one of strontium nitrate and strontium chloride; and / or, The promoter element II is derived from a compound containing the promoter element II; preferably, among the promoter element II, the copper, zinc, and silver elements are respectively derived from a copper-containing compound, a zinc-containing compound, and a silver-containing compound; more preferably, the copper-containing compound is selected from at least one of copper nitrate, copper chloride, and copper sulfate, the zinc-containing compound is selected from at least one of zinc nitrate, zinc chloride, and zinc sulfate, and the silver-containing compound is selected from at least one of silver nitrate and silver chloride; and / or, The promoter element III is derived from a compound containing the promoter element III; preferably, among the promoter element III, the iron, bismuth, and cobalt elements are respectively derived from an iron-containing compound, a bismuth-containing compound, and a cobalt-containing compound; more preferably, the iron-containing compound is selected from at least one of iron nitrate, iron chloride, and iron sulfate, and / or, the bismuth-containing compound is selected from at least one of bismuth nitrate and bismuth acetate, and / or, the cobalt-containing compound is selected from at least one of cobalt nitrate, cobalt chloride, and cobalt sulfate; and / or, The promoter element IV is derived from a compound containing the promoter element IV; preferably, among the promoter element IV, the zirconium, niobium, and tungsten elements are respectively derived from a zirconium-containing compound, a niobium-containing compound, and a tungsten-containing compound; more preferably, the zirconium-containing compound is selected from at least one of zirconium nitrate, zirconium chloride, and zirconium sulfate, and / or, the niobium-containing compound is selected from at least one of niobium nitrate, niobium oxalate, and niobium pentachloride, and the tungsten-containing compound is selected from at least one of tungsten nitrate, tungsten chloride, and tungsten sulfate.

8. The catalyst according to any one of claims 1 to 7, characterized in that, The molar ratio of titanium element to vanadium element is 1:(0.005 - 0.5), the molar ratio of titanium element to potassium element is 1:(0.001 - 0.2), the molar ratio of titanium element to nickel element is 1:(0.0001 - 0.05), and the molar ratio of titanium element to the promoter element is 1:(0.0001 - 0.05), wherein the molar amounts of titanium element, vanadium element, potassium element, and nickel element are calculated based on the molar amounts of their oxides, and the molar amounts of the promoter element are calculated based on the molar amounts of their elements respectively.

9. The catalyst according to claim 8, characterized in that, The molar ratio of titanium element to promoter element I is 1:(0.0005 - 0.02), the molar ratio of titanium element to promoter element II is 1:(0.0005 - 0.02), the molar ratio of titanium element to promoter element III is 1:(0.0001 - 0.03), and the molar ratio of titanium element to promoter element IV is 1:(0.0001 - 0.05), wherein the molar amounts of titanium element, vanadium element, potassium element, and nickel element are calculated based on the molar amounts of their oxides, and the molar amounts of promoter element I, promoter element II, promoter element III, and promoter element IV are calculated based on the molar amounts of their elements respectively.

10. A preparation method of a catalyst for the selective oxidation of fluorene to prepare 9-fluorenone, preferably used for preparing the catalyst according to any one of claims 1 to 9, the preparation method comprising: First, mix the mixture containing the active component with a reducing agent to obtain an active slurry mixture, then load the active slurry mixture onto the carrier to obtain a catalyst precursor, and finally perform an activation treatment on the catalyst precursor to obtain the catalyst.

11. The preparation method according to claim 10, characterized in that, The mixture containing the active components is obtained as follows: Components sources including a titanium-containing compound, a vanadium-containing compound, a potassium-containing compound, a nickel-containing compound, and a compound containing a promoter element are added to a reducing agent to obtain the active slurry mixture; preferably, the compound containing the promoter element is selected from the mixture of a compound containing promoter element I, a compound containing promoter element II, a compound containing promoter element III, and a compound containing promoter element IV.

12. The preparation method according to claim 11, characterized in that, The reducing agent is selected from at least one of oxalic acid and ammonium hydrogen oxalate; preferably, the molar ratio of the reducing agent to the titanium-containing compound is 0.05 - 0.

3.

13. The preparation method according to claim 10, characterized in that, The loading is carried out by spraying.

14. Use of the catalyst according to any one of claims 1 to 9 or the catalyst obtained by the preparation method according to any one of claims 10 to 13 in the selective oxidation of fluorene to prepare 9-fluorenone.

15. A method for the selective oxidation of fluorene to prepare 9-fluorenone, comprising: 9-Fluorenone is prepared from a mixed gas of fluorene and air in the presence of the catalyst according to any one of claims 1 to 9 or the catalyst obtained by the preparation method according to any one of claims 10 to 13; Preferably, the concentration of fluorene in the mixed gas is 40-55 g / Nm 3 ; Preferably, the volumetric space velocity of the mixed gas is 1500 - 3500 h -1 ; Preferably, heating and heat removal are carried out using a molten salt bath, and the temperature of the molten salt is 350 - 410 °C.

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