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CN-121988379-A - Coupling catalyst for preparing olefin from synthesis gas, preparation method and application thereof

CN121988379ACN 121988379 ACN121988379 ACN 121988379ACN-121988379-A

Abstract

The invention provides a coupling type catalyst for preparing olefin from synthesis gas, a preparation method and application thereof, wherein the coupling type catalyst comprises metal carbide and a solid acid component; the metal carbide is obtained by reducing and carbonizing cobalt and/or iron, M1 element and M2 element metal oxide, and the solid acid component comprises at least one of molecular sieve, acidic metal oxide and natural mineral solid acid. The coupling catalyst in the invention generates low-carbon olefin with high selectivity through metal carbide, and solid acid promotes the further conversion of the low-carbon olefin through the acid site thereof, so that the CO conversion rate is greatly improved, the single-pass conversion rate and the total yield of olefin in the reaction of preparing olefin from synthetic gas are obviously improved, and the cooperative improvement of catalytic activity, olefin selectivity and stability in the conversion process of synthetic gas is realized.

Inventors

  • ZHONG LIANGSHU
  • QIAO SHAN
  • AN YUNLEI
  • LIN TIEJUN
  • SONG YANFANG

Assignees

  • 中国科学院上海高等研究院

Dates

Publication Date
20260508
Application Date
20260316

Claims (10)

  1. 1. A coupled catalyst for the production of olefins from synthesis gas, the coupled catalyst comprising a metal carbide and a solid acid component; The metal carbide is obtained by reduction and carbonization treatment of metal oxide containing active metal elements, structural auxiliary agent M1 elements and electronic auxiliary agent M2 elements, wherein the active metal elements are cobalt and/or iron, the structural auxiliary agent M1 elements are selected from one or more of Mn, al, zn, cu, ru, and the electronic auxiliary agent M2 elements are selected from one or more of alkali metals or alkaline earth metals; The solid acid component comprises at least one of molecular sieve, acidic metal oxide and natural mineral solid acid.
  2. 2. The coupled catalyst for preparing olefin from synthetic gas according to claim 1, wherein the molar ratio of active metal element to structure aid M1 element in the metal oxide is (1-5): (1-5); and/or, calculated by metal elements, the mass percentage of the electronic auxiliary agent M2 element in the metal oxide is 0-15 wt% and is not 0; and/or the electronic auxiliary agent M2 element is selected from one or more of Na, K, mg, ca, sr, ba.
  3. 3. The coupled catalyst for producing olefins from synthesis gas according to claim 1 wherein a mass ratio of the metal oxide to the solid acid component is 0.1:1 to 10:1.
  4. 4. A method for preparing the coupling catalyst for preparing olefin from synthesis gas according to any one of claims 1-3, which is characterized by comprising the following steps: s1, providing a metal salt solution containing active metal elements, a structural auxiliary agent M1 element and an electronic auxiliary agent M2 element and a precipitation solution containing a precipitant, performing coprecipitation reaction on the metal salt solution and the precipitation solution, and aging, washing and drying after the reaction to obtain a precursor; S2, calcining the precursor at 300-600 ℃ for 2-24 hours to obtain a metal oxide; s3, coupling the metal oxide and the solid acid component in a physical mixing mode to obtain a coupled metal oxide; s4, reducing the coupled metal oxide in a reducing gas at 300-600 ℃ for 2-24 hours to obtain reduced metal; and S5, carbonizing the reduced metal in carbonized gas at 200-350 ℃ for 2-48 hours to obtain the coupled catalyst.
  5. 5. The method for preparing a coupled catalyst for olefin production from synthesis gas according to claim 4, wherein step S1 comprises one or a combination of the following conditions: The precipitation solution containing the precipitant is at least one of carbonate, bicarbonate or hydroxide containing alkali metal or alkaline earth metal; the temperature of the coprecipitation reaction is 25-35 ℃; The PH value in the coprecipitation reaction process is 7.5-8.5; The aging time is 1-5 h.
  6. 6. The method of preparing a coupled catalyst for olefin production from synthesis gas according to claim 4, wherein the physical mixing in the step S3 is at least one of milling and ball milling.
  7. 7. The method of claim 4, wherein the reducing gas in the step S4 is a mixture of H 2 and an inert gas, and H 2 accounts for 10% -100% of the reducing gas by volume.
  8. 8. The method for preparing a coupled catalyst for preparing olefins from synthesis gas according to claim 4, wherein the carbonized gas in the step S5 is a mixture of CO and a diluent gas, wherein the CO accounts for 10% -100% of the carbonized gas by volume, and the diluent gas is at least one of H 2 and an inert gas.
  9. 9. The application of the coupling type catalyst is characterized in that the coupling type catalyst is applied to the reaction of preparing olefin from synthesis gas, wherein the coupling type catalyst is the coupling type catalyst in any one of claims 1-3 or the coupling type catalyst prepared by the preparation method in any one of claims 4-8.
  10. 10. The method for preparing olefin by using the coupled catalyst according to claim 9, wherein the reaction condition of the synthesis gas comprises the reaction temperature of 200-300 ℃, the reaction pressure of 0.1 mpa-5 mpa, the reaction space velocity of 500-20000H -1 and the volume ratio of H 2 to CO in the synthesis gas of 0.2:1-3:1.

Description

Coupling catalyst for preparing olefin from synthesis gas, preparation method and application thereof Technical Field The invention belongs to the technical field of catalytic conversion of synthesis gas, and particularly relates to a coupling catalyst for preparing olefin from synthesis gas, a preparation method and application thereof. Background Synthesis gas refers to a mixed gas of carbon monoxide and hydrogen, and can be generally prepared from non-petroleum resources such as coal, natural gas, biomass and the like. Since the invention of the Fischer-Tropsch synthesis technology, the Fischer-Tropsch synthesis technology has been developed as an important synthesis gas conversion path, however, the conventional Fischer-Tropsch synthesis process generally follows the Anderson-Schulz-Flory (ASF) distribution rule, and it is difficult to realize high-selectivity control on specific high-value-added products (such as olefins and oxygen-containing compounds), so that how to break through the selectivity limit is one of the long-standing key challenges in the field of catalytic conversion of synthesis gas. In recent years, the discovery of prismatic cobalt carbide based catalysts has provided a new direction for the production of olefins from synthesis gas. The specific crystal faces (such as (101) and (020) crystal faces) exposed by the catalyst can obviously inhibit methane generation under mild conditions, and realize higher low-carbon olefin selectivity, so that the traditional ASF distribution limit is broken through to a certain extent. Research shows that the generated Co 2 C crystal face can be effectively converted into the (101) crystal face and the (020) crystal face from the (111) crystal face by adding an auxiliary agent (such as manganese), the catalytic performance of the Co 2 C crystal face is optimized, and the Density Functional Theory (DFT) calculation result shows that the (020) crystal face has a lower CO dissociation energy barrier and a higher methane generation energy barrier compared with the Co 2 C (101) crystal face and the (111) crystal face. In addition, by constructing a hydrophobic shell layer on the surface of Co 2 C, the selectivity of byproduct carbon dioxide is effectively reduced. However, prismatic Co 2 C catalysts have relatively low intrinsic activity, resulting in still room for improvement in product yield. In the catalytic system, the cascade catalytic strategy can realize the synchronous improvement of the reaction conversion rate and the selectivity through the cooperation and relay of a plurality of active sites. The strategy is successfully applied to reactions such as aromatic hydrocarbon production by synthesis gas or carbon dioxide, and a typical system comprises coupling a metal-based catalyst with a molecular sieve to realize in-situ conversion of an intermediate and selective generation of a target product. Nevertheless, how to effectively apply the series-connection catalytic strategy to the reaction of preparing olefin from synthesis gas, especially to solve the problem of insufficient activity of metal carbide, and to construct a composite catalytic system with high activity and high selectivity, still has a technical problem to be solved in the field. Accordingly, there is a need to provide an improved solution to the above-mentioned deficiencies of the prior art. Disclosure of Invention In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a coupled catalyst for producing olefins from synthesis gas, a preparation method and applications thereof, which are used for solving the problem that it is difficult to simultaneously maintain high activity and high olefin selectivity of the metal carbide catalyst for directly producing olefins from synthesis gas in the prior art. To achieve the above and other related objects, the present invention provides a coupled catalyst for the production of olefins from synthesis gas, the coupled catalyst comprising a metal carbide and a solid acid component; The metal carbide is obtained by reduction and carbonization treatment of metal oxide containing active metal elements, structural auxiliary agent M1 elements and electronic auxiliary agent M2 elements, wherein the active metal elements are cobalt and/or iron, the structural auxiliary agent M1 elements are selected from one or more of Mn, al, zn, cu, ru, and the electronic auxiliary agent M2 elements are selected from one or more of alkali metals or alkaline earth metals; The solid acid component comprises at least one of molecular sieve, acidic metal oxide and natural mineral solid acid. Preferably, in the metal oxide, the molar ratio of the active metal element to the structural additive M1 element is (1-5). Preferably, the mass percentage of the electronic auxiliary agent M2 element in the metal oxide is 0-15 wt% and is not 0, calculated by metal element. Preferably, the electron auxiliary M2 element is selected