Ammonia oxidation catalyst as well as preparation method and application thereof

Abstract

The invention relates to an ammoxidation catalyst and a preparation method and application thereof, the prepared catalyst has the characteristics of high activity and good thermal stability, the catalyst is mainly applied to an ammoxidation reaction process for preparing nitriles from C7-C9 aromatic hydrocarbons, the reaction conversion rate can be greater than 98%, and the molar yield of the nitriles is greater than 85%. The catalyst prepared by the preparation process of the ammoxidation catalyst is suitable for large-scale industrial device application.

Description

Technical Field

[0001] The present invention belongs to the field of catalysts, and relates to an ammoxidation catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Nitrile products are important basic organic chemical raw materials and play a crucial role in the adjustment of the future energy structure and the development of the chemical industry. China is rich in oil resources. During the processes of petroleum cracking, platinum reforming, and coking, a relatively large amount of mixed xylene can be obtained. Through methods such as isomerization, cryogenic crystallization separation, adsorption separation, and complexation separation of the mixed xylene, p-xylene, m-xylene, o-xylene, etc. can be obtained. This provides a rich raw material source for the ammoxidation of aromatics.

[0003] In the 20th century, countries such as Japan conducted a large number of studies on the ammoxidation of m-xylene to prepare isophthalonitrile and completed industrialization. The research in China started in the 1970s, and the core of the research is the catalyst and its process. Countries such as Japan use V-based composite metal oxides, in which the atomic ratio of V:Cr is between 0.1 and 2. In most aspects, the catalytic performance is satisfactory; the product weight yield is high (generally more than 90%). However, the reaction raw materials are a mixture of organic materials and air. After mixing, the organic materials have the problem of crossing the explosion curve, and even the mixed materials are directly within the explosion limit (such as the raw material ratio for the production of acrylonitrile by ammoxidation of propylene). The high-speed flow of the gas generates static electricity due to friction with the inner wall of the reactor, and it is easy to generate static sparks, with extremely high potential risks.

[0004] Therefore, it is crucial to develop a catalyst that can have self-insulating properties under high-temperature reaction conditions to block the static electricity transfer of the mixed gas. Summary of the Invention

[0005] To solve the above problems, the present invention provides an ammoxidation catalyst, a preparation method thereof, and an application thereof. By improving the preparation process, the insulation property of the catalyst is improved, the risk of combustion and explosion during the reaction process is reduced, the catalyst has good stability, and the catalyst is not easily lost.

[0006] A preparation method of an ammoxidation catalyst includes the following steps:

[0007] Step 1: Prepare a first active component solution under the condition of power-on;

[0008] Step 2: Under the condition of power-off, ultrasonically ripen and suspend the first active component solution, and add a second active component under ultrasonic conditions. Mobile liquid film bubbles are formed on the surface of the active components during the ultrasonic process;

[0009] Step 3: Add a solvent and an acidic or alkaline colloidal solution to the solution in Step 2, introduce an electrified electromagnet module, and make the active components in the solution suspended;

[0010] Step 4: Remove the electromagnet module, remove the solvent, and then dry and calcine to obtain the catalyst.

[0011] Preferably, in Step 1, the current is controlled to be 0.005 A - 0.22 A, preferably 0.01 A - 0.2 A;

[0012] Preferably, in Step 1, the first active component includes vanadium and chromium;

[0013] Preferably, the molar ratio of vanadium to chromium is 1:0.1 - 5, preferably 1:0.5 - 3.5.

[0014] Preferably, in Step 1, the first active component solution further includes an acid, and the acid includes one or more of nitric acid or organic acids. The organic acid is a carboxylic acid or a sulfonic acid, preferably nitric acid, oxalic acid, and citric acid.

[0015] Preferably, in Step 1, the addition amount of the acid is 1% - 20% of the total mass of the solution, preferably 3% - 12%.

[0016] Preferably, the precursor of the first active component and the acid are added to water and mixed evenly to form the first active component solution. Using the direct current potential difference as the driving force, the inner lining of the insulating container is an electrochemical membrane, and vanadium and chromium are promoted to form corresponding solid particles and precipitate with the acid. The particle size range of the formed solid particles is 5 nm - 95 nm;

[0017] Preferably, the first active component solution is prepared in an insulating container.

[0018] Preferably, in Step 2, the ultrasonic frequency is 20 kHz - 110 kHz. During the ultrasonic process, trace amounts of water-insoluble gas contained inside the solid particles penetrate to the particle surface to form moving liquid film bubbles. Preferably, the particle size range of the moving liquid film bubbles is 1 nm - 1 mm, and the liquid film moving time is 1 - 2 h; thereby greatly reducing the pore content inside the particles and reducing the formation of cracks on the catalyst surface;

[0019] Preferably, in Step 2, the second active component includes Mo, optionally Bi, and the promoter M, where M is selected from one or more of Al, Na, K, P, B, Sb, Si, Ni, Pr, Mg, Cs, Nd, Ce, Ca, Ti, Cu, preferably P, B, Sb, Na, Si, K.

[0020] Among them, the molar ratio of V, Mo, Bi, and the promoter M is 1:0 - 2:0 - 2:0 - 10, preferably 1:0.1 - 1.5:0.004 - 1.2:4 - 15.

[0021] Preferably, in the third step, the current of the electromagnet is 0.015 A - 0.15 A, preferably 0.015 A - 0.12 A. The active components in the solution are under the interaction of magnetic force, gravity, and buoyancy to achieve balanced suspension, and the suspension time is 0.5 h - 3 h.

[0022] Preferably, in the third step, the solvent is selected from water, glycerol, ethanol, and phenolic resin, preferably phenolic resin and glycerol.

[0023] Preferably, in the third step, the addition amount of the solvent is 0.1 times to 70 times the mass of the vanadium oxide, preferably 0.2 times - 60 times.

[0024] Preferably, in the third step, the acidic or alkaline colloidal solution is selected from silica sol or aluminum sol solution.

[0025] Preferably, in the third step, the silica solution is selected from silica sol. The addition amount of the silica solution or aluminum sol solution is 4 times - 30 times the mass of the vanadium oxide, preferably 10 times - 22 times.

[0026] Preferably, in the fourth step, the solvent is removed by rotary heating evaporation, the heating temperature is 70 - 100 °C, preferably 80 °C - 100 °C, and the solid content of the solution is 10% - 70% after removing part of the solvent.

[0027] Preferably, the solution is dried at 200 °C - 350 °C and then calcined at a temperature of 500 °C - 700 °C for 3 - 10 h. After calcination, a catalyst powder with a uniform outer surface insulation is formed. Preferably, the surface resistivity of the catalyst powder is 2.4×10 5 Ω·m - 8.9×10 5 Ω·m.

[0028] In the present invention, the active components are added by adding their precursors. The precursors of the active components can be common precursors in the art, such as nitrates, chlorates, oxides, simple substances, organic acid salts, hydroxides, etc. of the active components. The selection of the precursors is common knowledge in the art and will not be elaborated here.

[0029] In some preferred embodiments of the present invention, the precursor of molybdenum is selected from one or two or more of molybdenum-containing compounds such as ammonium polymolybdate, molybdenum trioxide, molybdic acid, and molybdenum disulfide, preferably the water-soluble molybdenum salt ammonium polymolybdate.

[0030] The precursor of vanadium of the catalyst described in the present invention is selected from vanadium pentoxide, vanadium tetroxide, vanadium trioxide, ammonium metavanadate, sodium metavanadate, etc., preferably vanadium pentoxide.

[0031] The precursor of bismuth of the catalyst described in the present invention is selected from bismuth nitrate, bismuth carbonate, or bismuth organic acid salt, etc., preferably bismuth nitrate.

[0032] The precursor of cesium in the catalyst of the present invention is selected from one or more of cesium carbonate, cesium hydroxide, cesium nitrate, and cesium chloride, preferably cesium nitrate and cesium carbonate.

[0033] The present invention also provides a catalyst prepared by the preparation method described above. The structure of the catalyst is: V1Cr m Bi x Mo y M z O g , where M represents an active promoter, 0.1 < m < 5, 0 ≤ x < 2, 0 < y ≤ 2, and 0 < z ≤ 20, and g is the oxygen valence balance value.

[0034] Preferably, 0.5 ≤ m ≤ 3.5, 0.004 ≤ x ≤ 1.2, 0.1 ≤ y ≤ 1.5, and 4 ≤ z ≤ 15. The promoter M includes one or more of Al, Na, K, P, B, Sb, Si, Ni, Pr, Mg, Cs, Nd, Ce, Ca, Ti, Cu, etc., preferably P, B, Sb, Na, Si, K.

[0035] The catalyst has a specific surface area (BET) of 5 - 90 m 2 / g.

[0036] The present invention also provides the application of the catalyst prepared by the preparation method described above in the ammoxidation of hydrocarbons or alcohols to prepare nitrile compounds.

[0037] A method for preparing a nitrile compound, in which a hydrocarbon or an alcohol is subjected to an ammoxidation reaction under the catalytic action of the catalyst prepared by the preparation method of the present invention with oxygen, ammonia gas or liquid ammonia.

[0038] Preferably, the ammoxidation reaction temperature is 350 - 500 °C, preferably 400 - 450 °C; the absolute pressure is 0.04 - 0.3 MPa, preferably 0.05 - 0.15 MPa.

[0039] Preferably, the ammoxidation reaction is a gas-phase reaction, and all raw materials are gases. The total volume space velocity of the raw material gas is 500 - 2500 h -1 , preferably 1000 - 2000 h -1 .

[0040] Preferably, the raw material gas contains a diluent gas, and the molar ratio of the diluent gas to the hydrocarbon or alcohol is 5 - 45, preferably 7 - 45.

[0041] Preferably, the molar ratio of oxygen to the hydrocarbon or alcohol is 1 - 10, preferably 4 - 9.

[0042] Preferably, the molar ratio of ammonia to the hydrocarbon or alcohol is 0.5 - 15, preferably 1 - 10.

[0043] The diluting gas can be a mixture of one or more of N2, H2O, He, and Ne, and the oxygen can be from pure oxygen or air.

[0044] The present invention has the following technical effects:

[0045] (1) In the first step of the present invention, the direct current potential difference is used as the driving force, and the inner lining of the insulating container is an electrochemical membrane, which promotes vanadium and chromium to precipitate solid particles with uniform particle size with acid. In the second step, during the ultrasonic process, trace amounts of water-insoluble gas contained inside the solid particles penetrate to the particle surface to form a moving liquid film bubble, thereby greatly reducing the pore content inside the particles, reducing the formation of cracks on the surface of the catalyst, reducing the catalyst abrasion, and extending the service life.

[0046] (2) The surface of the catalyst powder shows resistivity, thereby improving the insulation performance of the catalyst and reducing the risk of combustion and explosion during the reaction process. Specific Embodiments

[0047] The present invention will be further described below through examples, but the present invention is not limited to the following examples.

[0048] Example 1

[0049] Catalyst Preparation

[0050] Step 1: Prepare an active component solution in an insulating enamel bottle. Mix 50 g of vanadium pentoxide (chemical formula: V2O5), 109.96 g of chromium trioxide (CrO3), and 300 g of oxalic acid evenly into 3000 ml of water. During the mixing process, direct current is passed through the solution throughout, and the current is controlled at 0.04 A. After the material mixing is completed, a solid slurry suspension is formed, and the particle size distribution D50 of the suspension is about 50 nm;

[0051] Step 2: Ultrasonically ripen and suspend the solution in Step 1. The ultrasonic frequency range is 20 kHz. During the ultrasonic process, add 43.43 g of bismuth nitrate (Bi(NO3)3), 48.5 g of ammonium heptamolybdate (chemical formula: (NH4)6Mo7O 24 ·4H20), 11.1 g of potassium nitrate (KNO3), 9.57 g of boron trioxide (B2O3), and 19 g of 85% phosphoric acid (H3PO4). A 0.5 mm moving liquid film bubble is formed on the surface, and after the surface liquid film moves for 1.5 h, an active component is formed;

[0052] Step 3: Add 1000 g of 30% nano-silica solution and 80 g of phenolic resin solution to the active component solution in Step 2, introduce an energized electromagnet module, and control the electromagnet current at 0.05 A. The active components in the solution are affected by magnetic force, gravity, and buoyancy and reach a balanced suspension state, and the suspension time is 1 h;

[0053] Step 4: After the slurry suspension in Step 3 is completed, withdraw the electromagnetic current, start the rotation of the enamel kettle, heat and evaporate the solvent at 95°C, and control the solid content of the solution at 40%.

[0054] Step 5: The solution obtained in Step 4 is spray-dried at 250°C and calcined at 680°C for 3 h to form a powder catalyst with a uniform outer surface insulation. The specific surface area of the catalyst powder is 40 m 2 / g, and the surface resistivity is 2.8×10 5 Ω·m.

[0055] Oxidation experiment evaluation

[0056] Load 30 g of the finished catalyst into a 60-cm-long reactor. The reaction tube is a Ф25-mm stainless steel reaction tube. The catalyst pretreatment process is as follows: First, introduce air with a volumetric space velocity of 5000 h -1 , heat the reaction tube from room temperature to 300°C at a heating rate of 5°C / min and maintain it for 90 min, then switch to nitrogen purge for 80 min with a purge volumetric space velocity of 3000 h -1 . After the catalyst pretreatment is completed, carry out the ammoxidation reaction under the conditions of xylene:oxygen:nitrogen:ammonia = 1:8:30:8 (molar ratio), volumetric space velocity of 3000 h -1 (standard state), temperature of 390°C, and atmospheric pressure. Reaction results: The initial xylene conversion rate is 99.5%, and the phthalonitrile selectivity is 85.2%. After running for 4000 h, the xylene conversion rate is 99.2%, and the phthalonitrile selectivity is 85%. The surface resistivity of the catalyst powder is 2.78×10 5 Ω·m.

[0057] Example 2

[0058] Step 1: Prepare an active component solution in an insulating container, an enamel bottle. Uniformly mix 50 g of vanadium pentoxide (chemical formula V2O5), 10.99 g of chromium trioxide (CrO3), and 100 g of oxalic acid into 2000 ml of water. During the mixing process, direct current is passed through the solution throughout, and the current is controlled at 0.2 A. After the material mixing is completed, a solid slurry suspension is formed, and the particle size distribution D50 of the suspension is about 35 nm.

[0059] Step 2: Ultrasonically ripen and suspend the solution in Step 1. The ultrasonic frequency range is 110 kHz. During the ultrasonic process, add 412.6 g of bismuth nitrate (Bi(NO3)3), 194.1 g of ammonium heptamolybdate (chemical formula (NH4)6Mo7O 24 ·4H20), 166.8 g of potassium nitrate (KNO3), 95.7 g of boron trioxide (B2O3), and 126.8 g of 85% phosphoric acid (H3PO4). A moving liquid film bubble with a thickness of 0.8 mm is formed on the surface. After the surface liquid film moves for 1.5 h, an active component is formed.

[0060] Step 3: Add 800 g of 30% nano-silica solution and 60 g of phenolic resin solution to the active component solution in Step 2, introduce an energized electromagnet module, control the electromagnet current at 0.08 A, and the active components in the solution are under the interaction of magnetic force, gravity, and buoyancy to achieve balanced suspension for 1 h;

[0061] Step 4: After the slurry suspension in Step 3 is completed, withdraw the electromagnet current, start the rotation of the enamel kettle, heat and evaporate the solvent at 98 °C, and control the solid content of the solution at 50%;

[0062] Step 5: The solution with the solid content meeting the requirement of Step 4 is spray-dried at 200 °C and calcined at 580 °C for 6 h to form a powder catalyst with a uniform outer surface insulation. The specific surface area of the catalyst powder is 80 m 2 / g, and the surface resistivity is 2.6×10 5 Ω·m.

[0063] Oxidation experiment evaluation

[0064] Load 30 g of the finished catalyst into a 60-cm-long reactor. The reaction tube is a Ф25-mm stainless steel reaction tube. The catalyst pretreatment process is as follows: First, introduce air with a volumetric space velocity of 5000 h -1 , heat the reaction tube temperature from room temperature to 300 °C at a heating rate of 5 °C / min, and maintain it for 90 min. Then switch to nitrogen purge for 80 min with a purge volumetric space velocity of 3000 h -1 . After the catalyst pretreatment is completed, carry out the ammoxidation reaction under the conditions of xylene:oxygen:nitrogen:ammonia = 1:8:30:8 (molar ratio), volumetric space velocity of 3000 h -1 (standard state), temperature of 390 °C, and atmospheric pressure. Reaction results: The initial xylene conversion rate is 99.6%, and the phthalonitrile selectivity is 86.2%. After running for 4000 h, the xylene conversion rate is 99.3%, and the phthalonitrile selectivity is 86%. The surface resistivity of the catalyst powder is 2.65×10 5 Ω·m.

[0065] Example 3

[0066] Step 1: Prepare an active component solution in an insulated enamel bottle. Uniformly mix 50 g of vanadium pentoxide (chemical formula: V2O5), 65.97 g of chromium trioxide (CrO3), and 200 g of oxalic acid into 1000 ml of water. During the mixing process, direct current is passed through the solution throughout, and the current is controlled at 0.02 A. After the material mixing is completed, a solid slurry suspension is formed, and the particle size distribution D50 of the suspension is about 75 nm;

[0067] Step 2: Ultrasonically ripen and suspend the solution in Step 1. The ultrasonic frequency ranges from 70 kHz. During the ultrasonic process, 2.17 g of bismuth nitrate (Bi(NO3)3), 19.4 g of ammonium heptamolybdate (chemical formula: (NH4)6Mo7O 24 ·4H20), 38.9 g of potassium nitrate (KNO3), 153.1 g of boron trioxide (B2O3), 31.7 g of 85% phosphoric acid (H3PO4) are added. A mobile liquid film bubble with a thickness of 0.4 mm is formed on the surface. After the surface liquid film moves for 1.5 h, active components are formed;

[0068] Step 3: Add 500 g of 30% nano-silica solution and 30 g of phenolic resin solution to the active component solution in Step 2. Introduce an energized electromagnet module. Control the electromagnet current at 0.1 A. The active components in the solution are under the interaction of magnetic force, gravity, and buoyancy, and achieve balanced suspension for 1 h;

[0069] Step 4: After the slurry suspension in Step 3 is completed, withdraw the electromagnet current, start the rotation of the enamel kettle, heat and evaporate the solvent at 85 °C, and control the solid content of the solution at 20%;

[0070] Step 5: The solution with the solid content meeting the requirement of Step 4 is spray-dried at 220 °C and calcined at 600 °C for 5 h to form a powder catalyst with a uniform insulating outer surface. The specific surface area of the catalyst powder is 15 m 2 / g, and the surface resistivity is 2.9×10 5 Ω·m.

[0071] Oxidation experiment evaluation

[0072] Load 30 g of the finished catalyst into a 60 cm long reactor. The reaction tube is a Ф25 mm stainless steel reaction tube. The catalyst pretreatment process is as follows: First, introduce air with a volumetric space velocity of 5000 h -1 , heat the reaction tube from room temperature to 300 °C at a heating rate of 5 °C / min, and maintain it for 90 min. Then switch to nitrogen purge for 80 min, and the purge volumetric space velocity is 3000 h -1 . After the catalyst pretreatment is completed, carry out the ammoxidation reaction under the conditions of xylene:oxygen:nitrogen:ammonia = 1:8:30:8 (molar ratio), volumetric space velocity of 3000 h -1 (standard state), temperature of 390 °C, and normal pressure. Reaction results: The initial xylene conversion rate is 99.4%, and the phthalonitrile selectivity is 85.6%. After 4000 h of operation, the xylene conversion rate is 99.3%, and the phthalonitrile selectivity is 85.2%. The surface resistivity of the catalyst powder is 2.88×10 5 Ω·m.

[0073] Example 4

[0074] Step 1: Prepare the active component solution in an insulated enamel container. Uniformly mix 50 g of vanadium pentoxide (chemical formula: V2O5), 247.4 g of chromium trioxide (CrO3), and 300 g of oxalic acid into 3000 ml of water. During the mixing process, direct current is passed through the solution throughout, and the current is controlled at 0.033 A. After the material mixing is completed, a solid slurry suspension is formed, and the particle size distribution D50 of the suspension is approximately 55 nm.

[0075] Step 2: Ultrasonically ripen and suspend the solution in Step 1. The ultrasonic frequency range is 40 kHz. During the ultrasonic process, add 2.17 g of bismuth nitrate (Bi(NO3)3), 116.5 g of ammonium heptamolybdate (chemical formula: (NH4)6Mo7O 24 ·4H20), 27.8 g of potassium nitrate (KNO3), 57.4 g of boron trioxide (B2O3), and 380.3 g of 85% phosphoric acid (H3PO4). A moving liquid film bubble with a thickness of 0.5 mm is formed on the surface. After the surface liquid film moves for 1.5 h, the active component is formed.

[0076] Step 3: Add 1000 g of 30% nano-silica solution and 80 g of phenolic resin solution to the active component solution in Step 2. Introduce an energized electromagnet module, and control the electromagnet current at 0.12 A. The active components in the solution are affected by magnetic force, gravity, and buoyancy and reach an equilibrium suspension state for 1 h.

[0077] Step 4: After the slurry suspension in Step 3 is completed, withdraw the electromagnet current, start the enamel kettle to rotate, and heat and evaporate the solvent at 80 °C to control the solid content of the solution at 18%.

[0078] Step 5: The solution with the solid content meeting the requirement in Step 4 is spray-dried at 330 °C and calcined at 550 °C for 8 h to form a powder catalyst with a uniform insulating outer surface. The specific surface area of the catalyst powder is 35 m 2 / g, and the surface resistivity is 7.3×10 5 Ω·m.

[0079] Oxidation experiment evaluation

[0080] Load 30 g of the finished catalyst into a 60 cm long reactor. The reaction tube is a Ф25 mm stainless steel reaction tube. The catalyst pretreatment process is as follows: First, introduce air with a volume space velocity of 5000 h -1 , heat the reaction tube from room temperature to 300 °C at a heating rate of 5 °C / min, and maintain it for 90 min. Then switch to nitrogen purge for 80 min, and the purge volume space velocity is 3000 h -1 . After the catalyst pretreatment is completed, under the conditions of xylene:oxygen:nitrogen:ammonia = 1:8:30:8 (molar ratio) and a volume space velocity of 3000 h -1(Standard state), the ammoxidation reaction is carried out at a temperature of 390 °C and under atmospheric pressure. Reaction results: The initial xylene conversion rate is 99.7%, and the phthalonitrile selectivity is 88%. After 4000 h of operation, the xylene conversion rate is 99.5%, and the phthalonitrile selectivity is 87.6%. The surface resistivity of the catalyst powder is 7.28×10 5 Ω·m.

[0081] Example 5

[0082] Step 1: Prepare an active component solution in an insulating container, an enamel flask. Mix 50 g of vanadium pentoxide (chemical formula: V2O5), 175.9 g of chromium trioxide (CrO3) and 250 g of oxalic acid evenly into 2500 ml of water. During the mixing process, direct current is passed through the solution throughout, and the current is controlled at 0.01 A. After the materials are mixed, a solid slurry suspension is formed, and the particle size distribution D50 of the suspension is about 90 nm;

[0083] Step 2: Ultrasonically ripen the suspension of the solution in Step 1. The ultrasonic frequency range is 90 kHz. During the ultrasonic process, add 0.22 g of bismuth nitrate (Bi(NO3)3), 77.7 g of ammonium heptamolybdate (chemical formula: (NH4)6Mo7O 24 ·4H20), 277.9 g of potassium nitrate (KNO3), 19.1 g of boron trioxide (B2O3), 6.34 g of 85% phosphoric acid (H3PO4). A 0.5 mm moving liquid film bubble is formed on the surface. After the surface liquid film moves for 1.5 h, an active component is formed;

[0084] Step 3: Add 800 g of 30% nano-silica solution and 90 g of phenolic resin solution to the active component solution in Step 2. Introduce an energized electromagnet module, and control the electromagnet current at 0.015 A. The active components in the solution are affected by magnetic force, gravity and buoyancy, and achieve balanced suspension. The suspension time is 1 h;

[0085] Step 4: After the slurry suspension in Step 3 is completed, withdraw the electromagnet current, start the enamel kettle to rotate, heat and evaporate the solvent at 88 °C, and control the solid content of the solution at 30%;

[0086] Step 5: The solution with the solid content meeting the requirement of Step 4 is spray-dried at 350 °C and calcined at 570 °C for 7 h to form a powder catalyst with a uniform outer surface insulation. The specific surface area of the catalyst powder is 55 m 2 / g, and the surface resistivity is 8.8×10 5 Ω·m.

[0087] Oxidation experiment evaluation

[0088] Load 30 g of the finished catalyst into a 60 cm long reactor. The reaction tube is a Ф25 mm stainless steel reaction tube. The catalyst pretreatment process is as follows: First, introduce air, and the volume space velocity is 5000 h-1 The reaction tube temperature was heated from room temperature to 300 °C at a heating rate of 5 °C / min and maintained for 90 min, and then switched to nitrogen purge for 80 min with a purge volumetric space velocity of 3000 h -1 . After the catalyst pretreatment was completed, the ammoxidation reaction was carried out under the conditions of xylene:oxygen:nitrogen:ammonia = 1:8:30:8 (molar ratio), a volumetric space velocity of 3000 h -1 (standard state), a temperature of 390 °C, and atmospheric pressure. Reaction results: The initial xylene conversion was 99.4%, and the phthalonitrile selectivity was 89%. After running for 4000 h, the xylene conversion was 99.1%, and the phthalonitrile selectivity was 88.2%. The surface resistivity of the catalyst powder was 8.6×10 5 Ω·m.

[0089] Example 6

[0090] Step 1: Prepare an active component solution in an insulating container, an enamel flask. 50 g of vanadium pentoxide (chemical formula: V2O5), 38.48 g of chromium trioxide (CrO3), and 200 g of oxalic acid were uniformly mixed into 2200 ml of water. During the mixing process, direct current was passed through the solution throughout, and the current was controlled at 0.02 A. After the material mixing was completed, a solid slurry suspension was formed, and the particle size distribution D50 of the suspension was about 80 nm;

[0091] Step 2: The solution in Step 1 was ultrasonically aged and suspended. The ultrasonic frequency range was 85 kHz. During the ultrasonic process, 10.86 g of bismuth nitrate (Bi(NO3)3), 29.12 g of ammonium heptamolybdate (chemical formula: (NH4)6Mo7O 24 ·4H20), 89.57 g of cesium carbonate (Cs2CO3), 14.57 g of sodium carbonate (Na2CO3), and 76.06 g of 85% phosphoric acid (H3PO4) were added. A moving liquid film bubble with a surface of 0.6 mm was formed. After the surface liquid film moved for 1.6 h, the active component was formed;

[0092] Step 3: 700 g of 30% nano-silica solution and 80 g of phenolic resin solution were added to the active component solution in Step 2, and an energized electromagnet module was introduced. The electromagnet current was controlled at 0.05 A. The active components in the solution were under the interaction of magnetic force, gravity, and buoyancy and reached an equilibrium suspension. The suspension time was 1.5 h;

[0093] Step 4: After the slurry suspension in Step 3 was completed, the electromagnet current was withdrawn, and the enamel kettle was rotated. The solvent was evaporated by heating at 85 °C, and the solid content of the solution was controlled at 35%;

[0094] Step 5: The solution with the solid content meeting the requirement of Step 4 was spray-dried at 310 °C and calcined at 580 °C for 8 h to form a powder catalyst with a uniform outer surface insulation. The specific surface area of the catalyst powder was 50 m 2 / g, surface resistivity 6.8×10 5 Ω·m.

[0095] Oxidation experiment evaluation

[0096] Charge 30 g of the finished catalyst into a 60-cm long reactor. The reaction tube is a Ф25 mm stainless steel reaction tube. The catalyst pretreatment process is as follows: First, introduce air with a volume space velocity of 5000 h -1 , heat the reaction tube from room temperature to 300 °C at a heating rate of 5 °C / min and hold for 90 min, then switch to nitrogen purge for 80 min with a purge volume space velocity of 3000 h -1 . After the catalyst pretreatment is completed, carry out the ammoxidation reaction under the conditions of xylene:oxygen:nitrogen:ammonia = 1:8:30:8 (molar ratio), a volume space velocity of 3000 h -1 (standard state), a temperature of 390 °C, and atmospheric pressure. Reaction results: The initial xylene conversion rate is 99.2%, and the phthalonitrile selectivity is 90%. After running for 4000 h, the xylene conversion rate is 99.1%, and the phthalonitrile selectivity is 89.2%. The surface resistivity of the catalyst powder is 6.6×10 5 Ω·m.

[0097] Example 7

[0098] Step 1: Prepare an active component solution in an insulating enamel container. Uniformly mix 50 g of vanadium pentoxide (chemical formula V2O5), 88 g of chromium trioxide (CrO3), and 240 g of oxalic acid into 2400 ml of water. During the mixing process, direct current is passed through the solution with a current controlled at 0.012 A. After the material mixing is completed, a solid slurry suspension is formed, and the particle size distribution D50 of the suspension is about 88 nm;

[0099] Step 2: Ultrasonically ripen and suspend the solution in Step 1. The ultrasonic frequency range is 89 kHz. During the ultrasonic process, add 238.9 g of bismuth nitrate (Bi(NO3)3), 58.2 g of ammonium heptamolybdate (chemical formula (NH4)6Mo7O 24 ·4H20), 18.7 g of 30% aluminum sol solution, 1.91 g of boron trioxide (B2O3), and 38 g of 85% phosphoric acid (H3PO4). A 0.6-mm moving liquid film bubble is formed on the surface. After the surface liquid film moves for 1.5 h, an active component is formed;

[0100] Step 3: Add 600 g of 30% nano-silica solution and 100 g of phenolic resin solution to the active component solution in Step 2. Introduce an energized electromagnet module with the electromagnet current controlled at 0.016 A. The active components in the solution are under the interaction of magnetic force, gravity, and buoyancy and reach an equilibrium suspension for 1 h;

[0101] Step 4: After the slurry suspension in Step 3 is completed, withdraw the electromagnet current, start the rotation of the enamel reactor, heat and evaporate the solvent at 83 °C, and control the solid content of the solution to be 38%;

[0102] Step 5: The solution with the solid content meeting the requirement of Step 4 is spray-dried at 300 °C and calcined at 550 °C for 12 h to form a powder catalyst with a uniform insulating outer surface. The specific surface area of the catalyst powder is 60 m 2 / g, and the surface resistivity is 7.0×10 5 Ω·m.

[0103] Oxidation experiment evaluation

[0104] Load 30 g of the finished catalyst into a 60-cm-long reactor. The reaction tube is a Ф25-mm stainless steel reaction tube. The catalyst pretreatment process is as follows: First, introduce air with a volumetric space velocity of 5000 h -1 , heat the reaction tube from room temperature to 300 °C at a heating rate of 5 °C / min and maintain it for 90 min, then switch to nitrogen purge for 80 min with a purge volumetric space velocity of 3000 h -1 . After the catalyst pretreatment is completed, carry out the ammoxidation reaction under the conditions of xylene:oxygen:nitrogen:ammonia = 1:8:30:8 (molar ratio), volumetric space velocity of 3000 h -1 (standard state), temperature of 390 °C, and atmospheric pressure. Reaction results: The initial xylene conversion rate is 99.5%, and the phthalonitrile selectivity is 91%. After 4000 h of operation, the xylene conversion rate is 99.3%, and the phthalonitrile selectivity is 90.2%. The surface resistivity of the catalyst powder is 6.7×10 5 Ω·m.

[0105] Example 8

[0106] Step 1: Prepare an active component solution in an insulating container, an enamel bottle. Uniformly mix 50 g of vanadium pentoxide (chemical formula: V2O5), 121 g of chromium trioxide (CrO3), and 300 g of oxalic acid into 3000 ml of water. During the mixing process, pass direct current through the solution throughout, control the current to 0.01 A. After the material mixing is completed, form a solid slurry suspension with a D50 of the suspension particle size distribution of about 80 nm;

[0107] Step 2: Ultrasonically ripen and suspend the solution in Step 1. The ultrasonic frequency range is 85 kHz. During the ultrasonic process, add 4.34 g of bismuth nitrate (Bi(NO3)3), 126.2 g of ammonium heptamolybdate (chemical formula: (NH4)6Mo7O 24 ·4H20), 30.9 g of copper nitrate (Cu(NO3)2), 19.1 g of boron trioxide (B2O3), and 50.7 g of 85% phosphoric acid (H3PO4). Form a 0.6-mm moving liquid film bubble on the surface. After the surface liquid film moves for 1.5 h, form the active component;

[0108] Step 3: Add 800 g of 30% nano-silica solution and 100 g of phenolic resin solution to the active component solution in Step 2, introduce an energized electromagnet module, control the electromagnet current at 0.016 A, and the active components in the solution are under the interaction of magnetic force, gravity, and buoyancy to achieve balanced suspension for 1 h.

[0109] Step 4: After the slurry suspension in Step 3 is completed, withdraw the electromagnet current, start the rotation of the enamel kettle, heat and evaporate the solvent at 85 °C, and control the solid content of the solution at 33%.

[0110] Step 5: The solution with the solid content meeting the requirement of Step 4 is spray-dried at 280 °C and calcined at 600 °C for 5 h to form a powder catalyst with a uniform insulating outer surface. The specific surface area of the catalyst powder is 45 m 2 / g, and the surface resistivity is 7.2×10 5 Ω·m.

[0111] Oxidation experiment evaluation

[0112] Load 30 g of the finished catalyst into a 60 cm long reactor. The reaction tube is a Ф25 mm stainless steel reaction tube. The catalyst pretreatment process is as follows: First, introduce air with a volumetric space velocity of 5000 h -1 , heat the reaction tube from room temperature to 300 °C at a heating rate of 5 °C / min and maintain it for 90 min, then switch to nitrogen purge for 80 min with a purge volumetric space velocity of 3000 h -1 . After the catalyst pretreatment is completed, carry out the ammoxidation reaction under the conditions of xylene:oxygen:nitrogen:ammonia = 1:8:30:8 (molar ratio), volumetric space velocity of 3000 h -1 (standard state), temperature of 390 °C, and atmospheric pressure. Reaction results: The initial xylene conversion rate is 99.3%, and the phthalonitrile selectivity is 91.2%. After running for 4000 h, the xylene conversion rate is 99.1%, and the phthalonitrile selectivity is 90%. The surface resistivity of the catalyst powder is 7.0×10 5 Ω·m.

[0113] Example 9

[0114] Step 1: Prepare an active component solution in an insulating container, an enamel flask. Uniformly mix 50 g of vanadium pentoxide (chemical formula: V2O5), 154 g of chromium trioxide (CrO3), and 280 g of oxalic acid into 2800 ml of water. During the mixing process, direct current is passed through the solution throughout, and the current is controlled at 0.016 A. After the material mixing is completed, a solid slurry suspension is formed, and the particle size distribution D50 of the suspension is about 70 nm.

[0115] Step 2: The solution obtained in Step 1 is ultrasonically aged and suspended. The ultrasonic frequency ranges from 70 kHz. During the ultrasonic process, 1.09 g of bismuth nitrate (Bi(NO3)3), 14.6 g of ammonium heptamolybdate (chemical formula: (NH4)6Mo7O 24 ·4H2O), 169.2 g of antimony nitrate (Sb(NO3)3), 42.1 g of boron trioxide (B2O3), 190.2 g of 85% phosphoric acid (H3PO4) are added. A moving liquid film bubble with a thickness of 0.6 mm is formed on the surface. After the surface liquid film moves for 1.5 h, active components are formed;

[0116] Step 3: 900 g of 30% nano-silica solution and 80 g of phenolic resin solution are added to the active component solution obtained in Step 2. An energized electromagnet module is introduced. The electromagnet current is controlled at 0.015 A. The active components in the solution are under the interaction of magnetic force, gravity, and buoyancy, and achieve balanced suspension. The suspension time is 1 h;

[0117] Step 4: After the slurry suspension in Step 3 is completed, the electromagnet current is withdrawn, and the enamel kettle is rotated to heat and evaporate the solvent at 90 °C, controlling the solid content of the solution at 40%;

[0118] Step 5: The solution with the solid content meeting the requirement of Step 4 is spray-dried at 280 °C and calcined at 610 °C for 4 h to form a powder catalyst with a uniform insulating outer surface. The specific surface area of the catalyst powder is 60 m 2 / g, and the surface resistivity is 7.3×10 5 Ω·m.

[0119] Oxidation experiment evaluation

[0120] 30 g of the finished catalyst is loaded into a 60-cm-long reactor. The reaction tube is a Ф25-mm stainless steel reaction tube. The catalyst pretreatment process is as follows: First, air is introduced with a volumetric space velocity of 5000 h -1 , and the temperature of the reaction tube is heated from room temperature to 300 °C at a heating rate of 5 °C / min and maintained for 90 min. Then, it is switched to nitrogen purge for 80 min, and the purge volumetric space velocity is 3000 h -1 . After the catalyst pretreatment is completed, the ammoxidation reaction is carried out under the conditions of xylene:oxygen:nitrogen:ammonia = 1:8:30:8 (molar ratio), volumetric space velocity of 3000 h -1 (standard state), temperature of 390 °C, and atmospheric pressure. Reaction results: The initial xylene conversion rate is 99.6%, and the phthalonitrile selectivity is 89.5%. After running for 4000 h, the xylene conversion rate is 99.3%, and the phthalonitrile selectivity is 88.8%. The surface resistivity of the catalyst powder is 6.9×10 5 Ω·m.

[0121] Comparative Example 1

[0122] Mix 50 g of vanadium pentoxide (chemical formula: V2O5), 175.9 g of chromium trioxide (CrO3), and 250 g of oxalic acid evenly into 2500 ml of water. After the mixing of the materials is completed, a solid slurry suspension is formed. Then add 0.22 g of bismuth nitrate (Bi(NO3)3), 77.7 g of ammonium heptamolybdate (chemical formula: (NH4)6Mo7O 24 ·4H20), 277.9 g of potassium nitrate (KNO3), 19.1 g of boron trioxide (B2O3), and 6.34 g of 85% phosphoric acid (H3PO4).

[0123] Then start rotating the above-mentioned active component solution, heat and evaporate the solvent at 95°C, control the solid content of the solution to be 40%. The solution meeting the solid content is spray-dried at 250°C and calcined at 680°C for 5 h to form a powder catalyst with a uniform outer surface insulation. The catalyst powder has conductivity.

[0124] Oxidation experiment evaluation

[0125] The evaluation method is the same as that in Example 5, and the evaluation results are listed in Table 1.

[0126] Table 1 Evaluation results of catalysts in examples and comparative examples

[0127]

[0128]

[0129] Table 2 Molar composition ratios of various elements in examples and comparative examples

[0130] Element ratios Example 1 <![CDATA[V1Cr2Bi 0.2 Mo 0.5 K 0.2 B 0.5 P 0.3 Si 9.1 O g > Example 2 <![CDATA[V1Cr 0.2 Bi 1.9 Mo2K3B5P2Si 7.3 O g > Example 3 <![CDATA[V1Cr 1.2 Bi 0.01 Mo 0.2 K 0.7 B8P 0.5 Si 4.5 O g > Example 4 <![CDATA[V1Cr 4.5 Bi 0.01 Mo 1.2 K 0.5 B3P6Si 9.1 O g > Example 5 <![CDATA[V1Cr 3.2 Bi 0.001 Mo 0.8 K5B1P 0.1 Si 7.3 O g > Example 6 <![CDATA[V1Cr 0.7 Bi 0.05 Mo 0.3 Cs1Na 0.5 P 1.2 Si 6.4 O g > Example 7 <![CDATA[V1Cr 1.6 Bi 1.1 Mo 0.6 Al 0.2 B 0.1 P 0.6 Si 5.4 O g <!-- 9 -->]]> Example 8 <![CDATA[V1Cr 2.2 Bi 0.02 Mo 1.3 Cu 0.3 B1P 0.8 Si 7.3 O g > Example 9 <![CDATA[V1Cr 2.8 Bi 0.005 Mo 0.15 Sb1B 2.2 P3Si 8.2 O g > Comparative Example 1 <![CDATA[V1Cr 3.2 Bi 0.001 Mo 0.8 K5B1P 0.1 O g >

Claims

1. A method for preparing an ammonia oxidation catalyst, characterized in that, It includes the following steps: Step 1: Prepare the first active component solution under the condition of being powered on. Step 2: Under the condition of not being powered on, ultrasonically ripen and suspend the first active component solution, add the second active component under ultrasonic conditions, and mobile liquid film bubbles are formed on the surface of the active component during the ultrasonic process. Step 3: Add a solvent and an acidic or alkaline colloidal solution to the solution in Step 2, introduce an electrified electromagnet module to suspend the active component in the solution. Step 4: Remove the electromagnet module, remove the solvent, and then dry and calcine to obtain the catalyst.

2. The preparation method according to claim 1, wherein In Step 1, the current is controlled to be 0.005A - 0.22A, preferably 0.01A - 0.2A. Preferably, in Step 1, the first active component includes vanadium and chromium. Preferably, the molar ratio of vanadium to chromium is 1:0.1 - 5, preferably 1:0.5 - 3.

5.

3. The preparation method according to claim 1 or 2, characterized in that, In Step 1, the first active component solution further includes an acid, and the acid includes one or more of nitric acid or organic acids. The organic acid is carboxylic acid or sulfonic acid, preferably nitric acid, oxalic acid, and citric acid. Preferably, in Step 1, the addition amount of the acid is 1% - 20% of the total mass of the solution, preferably 3% - 12%. Preferably, the precursor of the first active component and the acid are added to water and mixed evenly to form the first active component solution.

4. The preparation method according to any one of claims 1-3, characterized in that, In Step 2, the ultrasonic frequency is 20kHz - 110kHz. Preferably, during the ultrasonic process, trace amounts of water-insoluble gas contained inside the solid particles penetrate to the particle surface to form mobile liquid film bubbles. The particle size range of the mobile liquid film bubbles is 1nm - 1mm, and the liquid film movement time is 1 - 2h. Preferably, in Step 2, the second active component includes Mo, optional Bi, and an auxiliary agent M, where M is selected from one or more of Al, Na, K, P, B, Sb, Si, Ni, Pr, Mg, Cs, Nd, Ce, Ca, Ti, Cu, preferably P, B, Sb, Na, Si, K. Preferably, the molar ratio of V, Mo, Bi, and the auxiliary agent M is 1:0 - 2:0 - 2:0 - 20, preferably 1:0.1 - 1.5:0.004 - 1.2:4 - 15.

5. The preparation method according to any one of claims 1-4, characterized in that, In Step 3, the electromagnet current is 0.015A - 0.15A, preferably 0.015A - 0.12A. The active component in the solution is suspended under the interaction of magnetic force, gravity, and buoyancy, and the suspension time is 0.5h - 3h. Preferably, in Step 3, the solvent is selected from water, glycerol, ethanol, phenolic resin, preferably phenolic resin and glycerol. Preferably, in Step 3, the addition amount of the solvent is 0.1 times to 70 times the mass of vanadium oxide, preferably 0.2 times - 60 times. Preferably, in Step 3, the acidic or alkaline colloidal solution is selected from silica sol or aluminum sol solution. Preferably, in Step 3, the addition amount of the silica sol or aluminum sol solution is 4 times - 30 times the mass of vanadium oxide, preferably 10 times - 22 times.

6. The preparation method according to any one of claims 1-5, characterized in that, In Step 4, the solvent is removed by rotary heating evaporation. The heating temperature is 70 - 100°C, preferably 80°C - 100°C. After removing part of the solvent, the solid content of the solution is 10% - 70%. Preferably, the solution is dried at 200°C - 350°C and then calcined at a temperature of 500°C - 700°C for 3 - 10h.

7. The catalyst prepared by the preparation method according to any one of claims 1-6, characterized in that, The catalyst structure is: V1Cr m Bi x Mo y M z O g , where M represents an active promoter, 0.1 < m < 5, 0 ≤ x < 2, 0 < y ≤ 2, and 0 < z ≤ 20, and g is the oxygen valence balance value; Preferably, 0.5 ≤ m ≤ 3.5, 0.004 ≤ x ≤ 1.2, 0.1 ≤ y ≤ 1.5, and 4 ≤ z ≤ 15. The promoter M comprises one or more of Al, Na, K, P, B, Sb, Si, Ni, Pr, Mg, Cs, Nd, Ce, Ca, Ti, Cu, preferably P, B, Sb, Na, Si, K.

8. Use of the catalyst prepared by the preparation method according to any one of claims 1-6 in the ammoxidation of hydrocarbons or alcohols to prepare nitrile compounds.

9. A method for preparing a nitrile compound, comprising subjecting a hydrocarbon or an alcohol to an ammoxidation reaction under the catalytic action of the catalyst prepared by the preparation method according to any one of claims 1-6 with oxygen, ammonia gas or liquid ammonia; Preferably, the ammoxidation reaction temperature is 350-500 °C, preferably 400-450 °C; the absolute pressure is 0.04-0.3 MPa, preferably 0.05-0.15 MPa; Preferably, the ammoxidation reaction is a gas-phase reaction, and all raw materials are gases. The total volume space velocity of the raw material gas is 500 to 2500 h -1 , preferably 1000 to 2000 h -1 ; Preferably, the feed gas contains a diluent gas, and the molar ratio of the diluent gas to the hydrocarbon or alcohol is 5-45, preferably 7-45; Preferably, the molar ratio of oxygen to the hydrocarbon or alcohol is 1-10, preferably 4-9; Preferably, the molar ratio of ammonia to the hydrocarbon or alcohol is 0.5-15, preferably 1-10; Preferably, the diluent gas is a mixture of one or more of N2, H2O, He, Ne.

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