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CN-121988377-A - Composite molecular sieve carrier iron catalyst, preparation method and application thereof, and method for preparing low-carbon olefin by synthesis gas one-step method

CN121988377ACN 121988377 ACN121988377 ACN 121988377ACN-121988377-A

Abstract

The invention relates to the technical field of catalyst preparation, and provides a composite molecular sieve carrier iron catalyst, a preparation method and application thereof, and a method for preparing low-carbon olefin by using synthesis gas in one step. The composite molecular sieve carrier iron catalyst comprises at least one of a component a) iron element and an oxide thereof, at least one of a component b) manganese element and an oxide thereof, at least one of a component c) lanthanide element and an oxide thereof, at least one of a component d) alkali metal element and an oxide thereof, and a component e) composite molecular sieve carrier, wherein the composite molecular sieve carrier comprises at least one of titanium element and an oxide thereof and a ZSM-5 molecular sieve. The composite molecular sieve carrier iron catalyst provided by the invention can promote the dispersion of manganese species and enhance the wear resistance of the catalyst by adopting the composite molecular sieve carrier while maintaining a larger specific surface area, and has the advantages of good stability and high low-carbon olefin selectivity in the reaction of preparing low-carbon olefin by one-step synthesis gas.

Inventors

  • LI JIANFENG
  • PANG YINGCONG
  • DAI YIMIN

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
20260508
Application Date
20241108

Claims (10)

  1. 1. The composite molecular sieve carrier iron catalyst is characterized by comprising the following components: component a) at least one of elemental iron and its oxides; At least one of the manganese element and its oxides of component b); component c) at least one of the lanthanoids and their oxides; Component d) at least one of an alkali metal element and its oxide; component e) a composite molecular sieve carrier; The composite molecular sieve carrier comprises at least one of titanium element and oxide thereof and a ZSM-5 molecular sieve.
  2. 2. The composite molecular sieve supported iron catalyst of claim 1, comprising the following components in parts by weight: 15-30 parts of a component a) calculated by Fe 2 O 3 ; 10-20 parts of component b) calculated by MnO; 1-10 parts of a component c) calculated by lanthanide oxide; 1-10 parts of component d) calculated by alkali metal element oxide; 30-75 parts of component e).
  3. 3. The composite molecular sieve supported iron catalyst of claim 1 or 2, wherein the lanthanide element comprises at least one of gadolinium and erbium; And/or the alkali metal element comprises at least one of cesium and sodium.
  4. 4. The composite molecular sieve carrier iron catalyst according to any one of claims 1 to 3, wherein the mass of at least one of the titanium element and the oxide thereof calculated by TiO 2 is 5 to 25% of the mass of the composite molecular sieve carrier; And/or the SiO 2 /Al 2 O 3 molar ratio of the ZSM-5 molecular sieve is 200-550.
  5. 5. The method for preparing the composite molecular sieve carrier iron catalyst according to any one of claims 1 to 4, which is characterized by comprising the steps of preparing a mixed solution comprising a component a) precursor, a component b) precursor, a component c) precursor and a component d) precursor, dipping the mixed solution on a composite molecular sieve carrier, drying, and performing second roasting to obtain the composite molecular sieve carrier iron catalyst.
  6. 6. The preparation method of the composite molecular sieve carrier according to claim 5, wherein the preparation method comprises the steps of dissolving ZSM-5 molecular sieve in a solvent, adding tetrabutyl titanate, mixing and stirring, adding water, mixing and stirring, solid-liquid separation, washing, drying and first roasting of precipitate to obtain the composite molecular sieve carrier.
  7. 7. The preparation method according to claim 6, wherein the solvent comprises an alcoholic solvent, preferably isopropanol and/or ethanol; And/or, dissolving the ZSM-5 molecular sieve in isopropanol by adopting ultrasonic dissolution; and/or, the first firing is performed in air; And/or the first roasting temperature is 350-550 ℃ and the roasting time is 4-18 h.
  8. 8. The production method according to any one of claims 5 to 7, wherein the second firing is performed in air; And/or the second roasting temperature is 400-600 ℃ and the second roasting time is 6-24 h.
  9. 9. Use of the composite molecular sieve supported iron catalyst of any one of claims 1-4 or prepared by the preparation method of any one of claims 5-8 in the one-step synthesis of low carbon olefins.
  10. 10. A method for preparing low-carbon olefin by one-step synthesis gas, which is characterized by comprising the steps of contacting and reacting a raw material comprising synthesis gas with the composite molecular sieve carrier iron catalyst prepared by the preparation method according to any one of claims 1-4 or the composite molecular sieve carrier iron catalyst prepared by the preparation method according to any one of claims 5-8 to generate low-carbon olefin; Preferably, the method comprises the steps of, The reaction temperature is 280-450 ℃; and/or the reaction pressure is 0.5-5.0 MPa; And/or the volume airspeed of the raw material gas is 2000-15000 h -1 ; And/or the molar ratio of H 2 to CO in the synthesis gas is 1-4.

Description

Composite molecular sieve carrier iron catalyst, preparation method and application thereof, and method for preparing low-carbon olefin by synthesis gas one-step method Technical Field The invention relates to the technical field of catalyst preparation, in particular to a composite molecular sieve carrier iron catalyst, a preparation method and application thereof, and a method for preparing low-carbon olefin by using synthesis gas in one step. Background The low-carbon olefin with the carbon number less than or equal to 4 is directly prepared through the Fischer-Tropsch synthesis catalyst by the one-step method reaction of the synthesis gas, the process flow can be simplified, the investment is reduced, the synthesis gas can be produced by taking crude oil, natural gas, coal and renewable materials as raw materials, and the raw material sources are widened for the production of the low-carbon olefin. The Fischer-Tropsch synthesis catalyst is mainly an iron-based catalyst, and can make the product diffuse away from an active center in time by utilizing a large specific surface area of a molecular sieve carrier and a proper pore channel structure, inhibit secondary reaction, and can enhance the bond energy of an active component and carbon, inhibit methane generation and improve the selectivity of low-carbon olefin by adding proper transition metal and electron promoting auxiliary agent. However, the existing iron-based catalyst for preparing the low-carbon olefin by using the synthesis gas through one-step method generally has the problem of unsatisfactory stability. Disclosure of Invention The invention aims to provide a composite molecular sieve carrier iron catalyst, a preparation method and application thereof, and a method for preparing low-carbon olefin by one-step synthesis gas, so as to solve the technical problem that the stability of an iron-based catalyst for preparing low-carbon olefin by one-step synthesis gas in the prior art is not ideal. In order to achieve the above purpose, the invention adopts the following technical scheme: in a first aspect, the invention provides a composite molecular sieve supported iron catalyst comprising the following components: component a) at least one of elemental iron and its oxides; At least one of the manganese element and its oxides of component b); component c) at least one of the lanthanoids and their oxides; Component d) at least one of an alkali metal element and its oxide; component e) a composite molecular sieve carrier; The composite molecular sieve carrier comprises at least one of titanium element and oxide thereof and a ZSM-5 molecular sieve. The composite molecular sieve carrier adopted in the composite molecular sieve carrier iron catalyst provided by the invention can promote the dispersion of manganese species and enhance the wear resistance of the catalyst while maintaining a larger specific surface area, thereby obviously improving the stability of the catalyst and being beneficial to improving the selectivity of low-carbon olefin. According to some embodiments of the invention, the composite molecular sieve supported iron catalyst comprises the following components in parts by mass: 15-30 parts of a component a) calculated by Fe 2O3; 10-20 parts of component b) calculated by MnO; 1-10 parts of a component c) calculated by lanthanide oxide; 1-10 parts of component d) calculated by alkali metal element oxide; 30-75 parts of component e). According to some embodiments of the invention, the lanthanide includes at least one of gadolinium and erbium. In the present invention, the lanthanide element selected gadolinium and/or erbium, can provide the catalyst with better stability and catalytic performance than other types of lanthanide elements. According to some embodiments of the invention, the alkali metal element comprises at least one of cesium and sodium. In the invention, cesium and/or sodium are selected as alkali metal elements, and compared with other alkali metal elements such as lithium, potassium and the like, the catalyst has better stability and catalytic performance. According to some embodiments of the present invention, the mass of at least one of the titanium element and the oxide thereof calculated as TiO 2 accounts for 5-25%, preferably 8-15%, of the mass of the composite molecular sieve carrier. According to some embodiments of the invention, the ZSM-5 molecular sieve has a SiO 2/Al2O3 molar ratio of 200 to 550, preferably 300 to 500. In a second aspect, the invention provides a preparation method of the composite molecular sieve carrier iron catalyst, which comprises the steps of preparing a mixed solution comprising a component a) precursor, a component b) precursor, a component c) precursor and a component d) precursor, impregnating the mixed solution on a composite molecular sieve carrier, drying, and roasting for the second time to obtain the composite molecular sieve carrier iron catalyst. According to some embodiments