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CN-122006732-A - Propylene ammoxidation catalyst, and preparation method and application thereof

CN122006732ACN 122006732 ACN122006732 ACN 122006732ACN-122006732-A

Abstract

The invention relates to the field of industrial catalysts, in particular to a propylene ammoxidation catalyst and a preparation method and application thereof. The propylene ammoxidation catalyst comprises a carrier and an active component, wherein the active component comprises Mo, bi, at least one alkaline earth metal element, at least one alkali metal element and at least one fourth-period VIII metal element, the catalyst starts to generate a reduction peak in the range of 350-390 ℃ in a hydrogen temperature programmed reduction H 2 -TPR test, and the reduction rate is 4 multiplied by 10 ‑ 4 a.u./℃-8×10 ‑4 a.u./° in the range of 420-450 ℃. The propylene ammoxidation catalyst has lower reduction temperature and faster reduction rate in the hydrogen programmed temperature reduction H 2 -TPR characterization, and has better reaction activity and long-term stability when being used for preparing acrylonitrile by propylene ammoxidation.

Inventors

  • WAN LI
  • LI JINGXIA
  • ZHANG QI
  • ZHOU XIAOFENG

Assignees

  • 中国石油化工股份有限公司
  • 中石化（上海）石油化工研究院有限公司

Dates

Publication Date
20260512
Application Date
20241111

Claims (10)

  1. 1. A propylene ammoxidation catalyst, characterized in that the catalyst comprises a carrier and an active component, the active component comprising Mo, bi, at least one alkaline earth metal element, at least one alkali metal element and at least one fourth group VIII metal element; Wherein, in the hydrogen temperature programmed reduction H 2 -TPR test, the catalyst starts to generate a reduction peak in the range of 350-390 ℃ and the reduction rate in the range of 420-450 ℃ is 4 multiplied by 10 -4 a.u./℃-8×10 -4 a.u./°.
  2. 2. The propylene ammoxidation catalyst of claim 1 wherein in a hydrogen temperature programmed reduction H 2 -TPR test the catalyst begins to exhibit a reduction peak in the range of 360-380 ℃; And/or in a hydrogen temperature programmed reduction H 2 -TPR test, the catalyst has a reduction rate of 5 x 10 -4 a.u./℃-6×10 -4 a.u./°c over the range of 420 ℃ to 450 ℃.
  3. 3. The propylene ammoxidation catalyst according to claim 1 or 2, wherein the active component has a general formula of Mo 12 Bi a A b B c C d O x , wherein, A is a fourth-period group VIII metal element, preferably at least two selected from Fe, co and Ni; B is an alkaline earth metal element, preferably at least one selected from Mg, ca and Sr; c is an alkali metal element, preferably at least one selected from K, cs and Rb; a. b, c, d and x represent the atomic numbers of the respective elements; a has a value in the range of 0.05 to 8, preferably 0.1 to 4; b has a value in the range of 0.05 to 12, preferably 0.1 to 8; c has a value in the range of 0.05 to 8, preferably 0.1 to 4; d has a value in the range of 0.02 to 2, preferably 0.05 to 1; x is the number of oxygen atoms required to satisfy the valence of the other element.
  4. 4. A propylene ammoxidation catalyst as claimed in any one of claims 1 to 3 wherein the carrier is present in an amount of from 35 to 65wt%, preferably 45 to 55wt% and the active component is present in an amount of from 35 to 65wt%, preferably 45 to 55wt%, based on the total amount of the propylene ammoxidation catalyst.
  5. 5. The propylene ammoxidation catalyst of any one of claims 1-4 wherein the support is selected from at least one of silica, alumina and titania, preferably silica.
  6. 6. A process for preparing the propylene ammoxidation catalyst of any one of claims 1-5 comprising the steps of: (1) Carrying out first mixing on the solution II containing the Mo element precursor and a first part of carrier precursor to obtain a first mixed solution; (2) Mixing the first mixed solution with a solution I containing a Bi element precursor, an alkaline earth metal element precursor, an alkali metal element precursor and a fourth-period VIII group metal element precursor and the rest of carrier precursor to obtain slurry; (3) And drying and roasting the slurry to obtain the propylene ammoxidation catalyst.
  7. 7. The method of claim 6, wherein the Mo element precursor, bi element precursor, alkaline earth element precursor, alkali element precursor, and fourth group VIII metal element precursor are water soluble salts corresponding to active metal elements; preferably, the water-soluble salt of Mo-containing element is an oxyacid ammonium salt of Mo-containing element, the water-soluble salts of Bi-containing element, alkaline earth metal element, alkali metal element and fourth-period group VIII metal element are each independently selected from at least one of nitrate, acetate, halide and alkoxide of the corresponding active metal element, preferably nitrate; preferably, the carrier precursor is selected from at least one of silica sol, white carbon black and silicon-based molecular sieve, preferably silica sol.
  8. 8. The method according to claim 6 or 7, wherein in the step (2), the method comprises the steps of S1, adding a solution I containing a Bi element precursor, an alkaline earth metal element precursor, an alkali metal element precursor and a fourth-period group VIII metal element precursor and a second part of a carrier precursor into the first mixed solution to carry out second mixing to obtain a second mixed solution, S2, adding a third part of a carrier precursor into the second mixed solution to carry out third mixing to obtain the slurry; Preferably, the content of the first part of carrier precursor is 40-60wt%, preferably 45-55wt%, the content of the second part of carrier precursor is 20-40wt%, preferably 25-35wt%, and the content of the third part of carrier precursor is 10-30wt%, preferably 15-25wt%, based on the total amount of the carrier precursors; preferably, the method in the step (2) further comprises the step of boiling the mixed product, wherein the condition of boiling the mixed product comprises the mixing temperature of 100-160 ℃ and preferably 120-150 ℃ under the stirring condition, and the mixing time is 10-40min and preferably 20-30min; Preferably, the stirring speed is 150-250r/min.
  9. 9. The method according to any one of claims 6-8, wherein the drying is spray drying, and the spray drying conditions include a spray drying temperature of 300-450 ℃, preferably 350-400 ℃, a spray drying time of 0.2-4 hours, preferably 0.5-1.5 hours, and a spray droplet average diameter of 30-130 μm, preferably 30-120 μm under an air atmosphere; preferably, the conditions of the calcination include a calcination temperature of 400-800 ℃, preferably 450-640 ℃, and a calcination time of 3-8 hours, preferably 4-6 hours, under an oxygen-containing atmosphere.
  10. 10. Use of a propylene ammoxidation catalyst as defined in any one of claims 1 to 5 or a propylene ammoxidation catalyst as defined in any one of claims 6 to 9 in the production of acrylonitrile by the ammoxidation of propylene; Preferably, the method for ammoxidation of propylene comprises the steps of ammoxidation of propylene with ammonia and oxygen in the presence of the propylene ammoxidation catalyst to produce acrylonitrile; Preferably, the molar ratio of propylene to ammonia to oxygen is 1:1-1.5:9-11, preferably 1:1.1-1.3:9.5-10; Preferably, the ammonia oxidation reaction conditions comprise a reaction temperature of 420-440 ℃, a reaction pressure of 0.06-0.12MPa and a reaction catalyst load of 0.08-0.12h -1 .

Description

Propylene ammoxidation catalyst, and preparation method and application thereof Technical Field The invention relates to the field of industrial catalysts, in particular to a propylene ammoxidation catalyst and a preparation method and application thereof. Background Acrylonitrile is an important organic chemical raw material, and has wide application market and prospect as a production raw material of chemicals such as acrylic fiber, ABS resin, polyacrylonitrile, carbon fiber and the like. Through decades of development, the current main production method of acrylonitrile is a preparation process of propylene, ammonia and air in a fluidized bed reactor under the action of catalyst particles prepared from active metals such as molybdenum, bismuth, iron and silicon dioxide carriers. Research shows that the uniform dispersion of the active metal in the catalyst to form small particles is favorable for improving the activity and long-term operation stability of the catalyst, and in practical industrial application, the active components of the catalyst often have sintering agglomeration of the active components due to long-term high-temperature operation, so that the activity is reduced, and the normal operation of a reaction device is not facilitated. Therefore, how to solve the problem of uniformity of particle size and distribution of active components in an acrylonitrile ammoxidation catalyst is an important research direction for maintaining the activity and stability of the acrylonitrile catalyst. CN107398288a discloses an acrylonitrile catalyst, which uses carrier modifiers such as silicon dioxide, alumina, montmorillonite and the like as a composite carrier, and uses metal oxide containing general formula a aBbLacFedBieMo13.6Ox as an active component, so that the problems of low selectivity and poor stability of the catalyst are better solved, and the catalyst can be used in industrial production of acrylonitrile by propylene ammoxidation. CN109772356a discloses an acrylonitrile catalyst and its preparation method and application, the catalyst comprises silicon dioxide carrier and metal oxide with general formula BiaFebNicMgdCeeAfBgChMo12Ox as active components, wherein B is one or more than two elements selected from the group consisting of praseodymium, europium, terbium and dysprosium, ammonia water stabilizer is added into silica sol carrier, the prepared acrylonitrile catalyst can meet the requirement of high catalyst load of industrial energy expanding device, also reduce the generation amount of carbonyl compound acrolein and acrylic acid, and improve the running period of the device. CN112584929a discloses a method for producing a catalyst for ammoxidation and a method for producing acrylonitrile, the catalyst comprising a composite metal oxide composed of the general formula Mo 12BiaFebXcYdZeOf, wherein Y represents 1 or more element selected from cerium, chromium, lanthanum, neodymium, yttrium, praseodymium, samarium, aluminum, gallium and indium, an aggregate containing a metal and a carrier is contained in a solid phase of a catalyst precursor slurry, a particle diameter of metal primary particles constituting the aggregate is 1 μm or less, and an average particle diameter of the metal primary particles is 40nm or more and 200nm or less, and the catalyst for ammoxidation having a high acrylonitrile yield is produced by controlling a particle size of the solid phase in the slurry. According to the technical scheme, although the catalytic activity of the acrylonitrile catalyst prepared by ammoxidation of propylene is improved to a certain extent, the problem of uneven dispersion of active components in a carrier is not solved well, and the long-term running stability of the catalyst still has room for improvement, so that development of an active and stable acrylonitrile ammoxidation catalyst is needed. Disclosure of Invention The invention aims to solve the problems of large active metal component particles and poor dispersibility of a propylene ammoxidation catalyst in the prior art and agglomeration into blocks, and provides a propylene ammoxidation catalyst and a preparation method and application thereof. In the hydrogen temperature programming reduction H 2 -TPR characterization, the propylene ammoxidation catalyst has lower reduction temperature and faster reduction rate, which indicates that the active component particles in the propylene ammoxidation catalyst are smaller and are uniformly compounded with the carrier, the active component has better dispersibility, and the catalyst has better reaction activity and long-term stability when being used for preparing acrylonitrile by propylene ammoxidation. In order to achieve the above object, a first aspect of the present invention provides a propylene ammoxidation catalyst comprising a carrier and an active component comprising Mo, bi, at least one alkaline earth metal element, at least one alkali metal element and at least one fourth