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CN-122006733-A - Molybdenum-bismuth-iron catalyst, preparation method and application thereof and olefin oxidation method

CN122006733ACN 122006733 ACN122006733 ACN 122006733ACN-122006733-A

Abstract

The invention relates to a molybdenum-bismuth-iron catalyst, a preparation method and application thereof and an olefin oxidation method, wherein the general formula of the catalyst is MoBi a Fe b X c Y d Z e Q f (Bi 4 Ti 3 O 12 ) g O j ;, X is at least one of alkaline earth metal element and VIII metal element, Y is at least one of VB metal element, VIB metal element and VA metal element, Z is at least one of alkali metal element, Q is at least one of rare earth element, a is 0.01-0.05, b is 0.1-0.5, c is 0.2-0.8, d is 0.1-0.5, e is 0.01-0.03, f is 0.01-0.04, and g is 0.5-3;j, and the total number of oxygen atoms required by each element in the catalyst is satisfied. The molybdenum-bismuth-iron catalyst has higher reactivity, can effectively improve the conversion rate of reactants, the selectivity of products and the yield of target products, and is particularly suitable for application in oxidation reaction, especially for application in olefin oxidation.

Inventors

  • SONG WEILIN
  • XU WENJIE
  • YANG BIN

Assignees

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

Dates

Publication Date
20260512
Application Date
20241111

Claims (10)

  1. 1. A molybdenum-bismuth-iron catalyst is characterized in that the catalyst has the general formula of MoBi a Fe b X c Y d Z e Q f (Bi 4 Ti 3 O 12 ) g O j ; Wherein X is at least one of alkaline earth metal element and VIII metal element, Y is at least one of VB group metal element, VIB group metal element and VA group metal element, Z is at least one of alkali metal element, Q is at least one of rare earth element; The value of a is 0.01-0.05, the value of b is 0.1-0.5, the value of c is 0.2-0.8, the value of d is 0.1-0.5, the value of e is 0.01-0.03, the value of f is 0.01-0.04, and the value of g is 0.5-3;j, which are the total number of oxygen atoms required by the valence of each element in the catalyst.
  2. 2. The catalyst according to claim 1, wherein, Bi 4 Ti 3 O 12 is present in the form of compounds and/or The average particle diameter of Bi 4 Ti 3 O 12 is 1 to 20. Mu.m, preferably 1 to 10. Mu.m.
  3. 3. The catalyst according to claim 1 or 2, wherein in the formula MoBi a Fe b X c Y d Z e Q f (Bi 4 Ti 3 O 12 ) g O j , X is selected from at least one of Mg, co and Ni, and/or Y is selected from at least one of Nb, W and Sb, and/or Z is selected from at least one of K, rb and Cs, and/or Q is at least one selected from Ce, la, nd, pr, preferably at least one selected from Ce, la and Nd, more preferably Ce and La, and the molar ratio of Ce to La is 2-5, preferably 3-4; And/or A is 0.02-0.04, b is 0.2-0.4, c is 0.4-0.7, d is 0.2-0.4, e is 0.01-0.02, f is 0.02-0.03, and g is 1-2.
  4. 4. A process for preparing the molybdenum-bismuth-iron catalyst as claimed in any one of claims 1 to 3, characterized in that the process comprises: Adding Bi 4 Ti 3 O 12 into a solution containing a Mo source, a Bi source, a Fe source, an X source, a Y source, a Z source and a Q source, mixing to obtain slurry, drying and roasting to obtain the molybdenum-bismuth-iron catalyst.
  5. 5. The preparation method according to claim 4, wherein the preparation method comprises: (1) Adding Bi 4 Ti 3 O 12 into a first solution containing a Mo source and a Y source, and mixing; (2) Adding the second solution containing the Bi source, the Fe source, the X source, the Z source and the Q source into the step (1), mixing to obtain slurry, drying and roasting to obtain the molybdenum-bismuth-iron catalyst.
  6. 6. A molybdenum-bismuth-iron catalyst produced by the process of any one of claims 4-5.
  7. 7. Use of the molybdenum-bismuth-iron catalyst as claimed in any one of claims 1 to 3, 6 in an oxidation reaction, preferably in the oxidation of an olefin, more preferably the olefin is a C3-C5 alpha-olefin.
  8. 8. A process for oxidizing olefins, which comprises contacting an olefin-containing feed gas with an oxidizing agent in the presence of the molybdenum-bismuth-iron catalyst as claimed in any one of claims 1 to 3 and 6.
  9. 9. The method of claim 8, wherein, The olefin is a C3-C5 alpha-olefin, preferably propylene, and/or The olefin-containing feed gas also comprises a diluent gas selected from inert gases and/or steam; And/or The oxidant is selected from one or more of oxidizing gases, preferably oxygen and/or air; And/or The volume ratio of the olefin to the diluent gas to the oxidant is 1:0.5-5:6-8.
  10. 10. The method according to claim 8 or 9, wherein, The conditions of the contact reaction include: at a temperature of 300-550 ℃, preferably 300-380 ℃, and/or Pressure of 0.01-0.08MPa, and/or The volume mass space velocity of the feed gas containing olefin is 600-1200 mL/g.h.

Description

Molybdenum-bismuth-iron catalyst, preparation method and application thereof and olefin oxidation method Technical Field The invention relates to a molybdenum-bismuth-iron catalyst, a preparation method and application thereof and an olefin oxidation method. Background The selective oxidation of olefins to produce unsaturated acids is an important chemical process. It is common in industry to oxidize an olefin to obtain an unsaturated aldehyde and then to oxidize the unsaturated aldehyde to obtain an unsaturated acid. The process is generally carried out in two stages, two reactors and two catalysts are used for completion under different reaction conditions, wherein one stage of reaction mainly generates acrolein, and about 20% of acrylic acid is also generated, and the active components of the catalyst are complex Mo and Bi composite oxide systems. The improvement of the general catalyst is mainly carried out in terms of the activity and stability of the catalyst, such as adding transition metal into the active component to improve the reaction activity and increase the yield of the product, adding rare earth elements to improve the oxidation-reduction capability, adding Fe, co, ni and other elements to inhibit the sublimation of Mo, stabilizing the active component of the catalyst and prolonging the service life of the catalyst. In addition, because of the intense exothermic phenomenon in the reaction, the control of the reaction temperature of the catalyst bed is very important, and the formation of hot spots not only leads the reaction activity of the catalyst to be poor, but also shortens the service life of the catalyst, thus influencing the stable operation of the device. It is believed that during the first step of propylene oxidation to acrolein, the olefin is adsorbed onto the catalyst surface and an alpha-H is removed by the metal oxide to form a free radical intermediate which is intercalated by oxygen to form the product. In this process, the catalyst undergoes a redox cycle process in which oxygen atoms lost to intercalation are reduced, then reoxidized by oxygen in the reaction gas, and the active site oxygen atoms are replenished by oxygen migration, so that the catalyst is required to have good oxygen migration capability to maintain the catalyst structure and redox balance. The prior art generally employs Mo, V, bi, te, nb, fe, co, ni or other transition metal complex oxides in which bismuth molybdate (Bi 2(MoO4)3) is the active site for the critical step alpha-H removal (CATALYSIS TODAY 49 (1999) 141-153). US4224187, US4248803 propose to increase the olefin conversion and the yield of the target product by improving the components of the catalyst and their ratio of amounts and the method of preparing the catalyst. The improved catalyst is used for the selective oxidation of isobutene, but the problem of low reaction selectivity still exists, wherein the isobutene conversion rate is as high as 99%, but the total yield of methacrolein and methacrylic acid is only 73.6%. US6268529 proposes a propylene oxidation catalyst with a propylene conversion of 98.1%, an acrolein yield of 65.3%, an acrylic acid yield of 20.8% and a total yield of acrolein and acrylic acid of only 86.1%. CN1564709 improves catalyst performance by adding organic carboxylic acid to overcome catalyst non-uniformity caused by layering between metal salts during the co-precipitation process of catalyst preparation. The method is used for the selective oxidation of propylene, wherein the propylene conversion rate is up to 98.12%, the acrolein selectivity is up to 82.53%, and the total yield of acrolein and acrylic acid is 91.05%. CN1210511A, CN1283604A, CN1314331a achieves the purpose of controlling reaction hot spot and prolonging catalyst stability by disposing a plurality of catalyst layers with gradually increased reactivity along the axial direction of the reactor from the inlet to the outlet of the reaction gas. But the structural stability of the catalyst is still further improved. Disclosure of Invention Aiming at the defects of the prior art, one of the technical problems to be solved by the invention is to provide a novel molybdenum-bismuth-iron catalyst which has higher reactivity, can effectively improve the conversion rate of reactants, the selectivity of products and the yield of target products, is particularly suitable for application in oxidation reaction, and is particularly suitable for application in olefin oxidation. In order to achieve the above object, the first aspect of the present invention provides a molybdenum-bismuth-iron catalyst having a general formula MoBiaFebXcYdZeQf(Bi4Ti3O12)gOj;, wherein X is at least one of an alkaline earth metal element and a group VIII metal element, Y is at least one of a group VB metal element, a group VIB metal element and a group VA metal element, Z is at least one of alkali metal elements, Q is at least one of rare earth elements, a has a value of 0.01 to 0.05, b