Search

CN-121988362-A - Iron catalyst, preparation method and application thereof, and method for preparing olefin by hydrogenation of carbon dioxide

CN121988362ACN 121988362 ACN121988362 ACN 121988362ACN-121988362-A

Abstract

The invention relates to the technical field of catalyst preparation, and provides an iron catalyst, a preparation method and application thereof, and a method for preparing olefin by carbon dioxide hydrogenation. The iron catalyst comprises an active component and a carrier in a mass ratio of (40-70) (30-60), wherein the active component comprises a composition with a chemical formula of Fe 100 A a K b O x (Fe 4 N) c in terms of atomic ratio, A comprises at least one of Mn, cu and Zn, a is 10-30, b is 1-10, c is 1-8, and x is the total number of oxygen atoms required for meeting the valence of each element in the catalyst. The iron catalyst provided by the invention contains iron oxide and iron nitride, can be used in the reaction of preparing olefin by carbon dioxide hydrogenation, is favorable for improving the carbon dioxide conversion rate and the selectivity of olefin, especially C 4 + olefin, and is suitable for a fluidized bed reactor, and the problems of difficult heat removal, easy temperature runaway and easy catalyst deactivation in high-temperature Fischer-Tropsch synthesis can be effectively solved.

Inventors

  • PANG YINGCONG
  • LI JIANFENG
  • 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. An iron catalyst is characterized by comprising an active component and a carrier in a mass ratio of (40-70): (30-60); The active component comprises a composition with a chemical formula of Fe 100 A a K b O x (Fe 4 N) c in terms of atomic ratio; Wherein A comprises at least one of Mn, cu and Zn, A is 10-30, B has a value of 1 to 10, C has a value range of 1 to 8, X is the total number of oxygen atoms required to satisfy the valence of each element in the catalyst.
  2. 2. The iron catalyst according to claim 1, characterized in that the support comprises oxides of Si and/or oxides of Ti.
  3. 3. The method for preparing the iron catalyst according to claim 1 or 2, which is characterized by comprising the steps of preparing ferric hydroxide sediment by adopting a first Fe precursor, preparing slurry comprising the ferric hydroxide sediment, an A precursor, a K precursor, a carrier precursor and water, adding iron nitride powder into the slurry, mixing and stirring, spray drying and roasting to obtain the iron catalyst.
  4. 4. The method according to claim 3, wherein the molar ratio of the first Fe precursor in terms of Fe element, the A precursor in terms of A element, and the K precursor in terms of K element is 100:10 to 30:1 to 10.
  5. 5. The method according to claim 3 or 4, wherein the baking atmosphere is air; and/or the roasting temperature is 500-800 ℃, and the roasting time is 0.5-10 h.
  6. 6. The method for preparing the iron nitride powder according to any one of claims 3 to 5, comprising preparing ferric hydroxide precipitate by using a second Fe precursor, drying in vacuum to obtain iron oxide powder, and nitriding the iron oxide powder in a mixed atmosphere comprising ammonia gas and hydrogen gas at 500-800 ℃ to obtain the iron nitride powder.
  7. 7. The preparation method according to claim 6, wherein the vacuum drying temperature is 40-80 ℃; and/or the nitriding treatment temperature is 550-750 ℃; and/or the nitriding treatment time is 3-30 hours; and/or the volume ratio of the ammonia gas to the hydrogen gas in the mixed atmosphere is 0.5-5:1.
  8. 8. The production method according to claim 6 or 7, characterized in that the molar ratio of the first Fe precursor to the second Fe precursor in terms of Fe element is 100:4 to 32; And/or the ratio of the sum of the mass of the first Fe precursor calculated as Fe 2 O 3 , the A precursor calculated as an oxide of A, the K precursor calculated as K 2 O and the second Fe precursor calculated as Fe 4 N to the mass of the carrier precursor calculated as the carrier is 40-70:30-60.
  9. 9. Use of the iron catalyst of claim 1 or 2 or the iron catalyst prepared by the preparation method of any one of claims 3 to 8 in a reaction for preparing olefins by hydrogenation of carbon dioxide.
  10. 10. A method for preparing olefin by hydrogenation of carbon dioxide, which is characterized by comprising the steps of contacting and reacting a raw material comprising CO 2 and H 2 with the iron catalyst according to claim 1 or 2 or the iron catalyst prepared by the preparation method according to any one of claims 3-8 to generate olefin; Preferably, the method comprises the steps of, The reaction temperature is 300-370 ℃; and/or the reaction pressure is 0.5-5.0 MPa; and/or the standard volume space velocity of the catalyst load is 4000-10000 h -1 ; and/or the molar ratio of CO 2 to H 2 is 1:1-5.

Description

Iron catalyst, preparation method and application thereof, and method for preparing olefin by hydrogenation of carbon dioxide Technical Field The invention relates to the technical field of catalyst preparation, in particular to an iron catalyst, a preparation method and application thereof, and a method for preparing olefin by hydrogenation of carbon dioxide. Background The dramatic increase in emissions of CO 2 as the primary greenhouse gas has led to a series of environmental and climate problems. How to achieve a technically net zero emission of CO 2 is a challenging task now in academia and industry. Wherein its conversion to chemicals in combination with green hydrogen is a very promising approach. The combination of green hydrogen and CO 2 not only can consume CO 2, but also can convert the CO 2 into valuable carbon-containing chemicals, reduce the dependence on fossil energy and provide a solving route for realizing net zero emission. Some technical methods for preparing carbonaceous chemicals by combining green hydrogen with CO 2 have been disclosed in the prior art. Among other things, patent CN110947384a discloses a process for the hydrogenation of CO 2 to methanol. Patent CN111790436B discloses a technology for converting CO 2 into aromatic hydrocarbons. Because of the stability of the molecules of CO 2 and the difficulty in carbon chain growth, the prior art for preparing organic hydrocarbons, especially olefins, by hydrogenating CO 2 mainly relates to the technology of using low-carbon olefins as main products, such as patent CN112169799B, CN104907080B and the like, and reports on preparing C 4 + olefins by hydrogenating CO 2 are relatively few. To improve the efficient utilization of CO 2, there is no surprise in developing techniques for the hydroconversion thereof to olefins, particularly C 4 + linear alpha olefins. In addition, the reaction for preparing olefin by CO 2 hydrogenation belongs to the Fischer-Tropsch synthesis reaction, and the Fischer-Tropsch synthesis, especially the high temperature Fischer-Tropsch synthesis, belongs to a strong exothermic process, so that the problems of difficult heat removal, easy temperature runaway and easy catalyst deactivation exist. Disclosure of Invention The invention aims to provide an iron catalyst, a preparation method and application thereof and a method for preparing olefin by hydrogenating carbon dioxide, so as to solve the technical problems of strong heat release and difficult heat removal in the Fischer-Tropsch synthesis reaction in the prior art. In order to achieve the above purpose, the invention adopts the following technical scheme: in a first aspect, the invention provides an iron catalyst, which comprises an active component and a carrier in a mass ratio of (40-70): (30-60); The active component comprises a composition with a chemical formula of Fe 100AaKbOx(Fe4N)c in terms of atomic ratio; Wherein A comprises at least one of Mn, cu and Zn, A has a value ranging from 10 to 30, for example, 10, 12, 14, 15, 16, 17, 20, 22, 23, 25, 26, 27, 28, 30, etc., B is 1 to 10, for example, 1,2,3,4, 5, 6, 7, 8, 9, 10, etc., The value of c is 1 to 8, and may be, for example, 1,2, 3, 4, 5, 6, 7, 8, etc., and x is the total number of oxygen atoms required to satisfy the valence of each element in the catalyst. The iron catalyst provided by the invention comprises iron oxide and iron nitride, and the molar ratio of the iron oxide to the iron nitride on the surface of the catalyst, calculated as Fe, is the same as that in a bulk phase. According to some embodiments of the invention, the molar ratio of iron oxide to iron nitride on the surface of the catalyst, calculated as Fe, is 100:4-32. According to some embodiments of the invention, the support comprises an oxide of Si and/or an oxide of Ti. In a second aspect, the invention provides a preparation method of the iron catalyst in the first aspect, which comprises the steps of adopting a first Fe precursor to prepare ferric hydroxide sediment, preparing slurry comprising the ferric hydroxide sediment, an A precursor, a K precursor, a carrier precursor and water, adding iron nitride powder into the slurry, mixing and stirring, spray drying and roasting to obtain the iron catalyst. According to some embodiments of the present invention, the molar ratio of the first Fe precursor in terms of Fe element, the a precursor in terms of a element, and the K precursor in terms of K element is 100:10 to 30:1 to 10. According to some embodiments of the invention, the first Fe precursor comprises at least one of Fe salts, such as ferric nitrate, ferric chloride, ferric citrate, and the like. According to some embodiments of the invention, preparing the ferric hydroxide precipitate using the first Fe precursor includes mixing the first Fe precursor with the precipitate to prepare the ferric hydroxide precipitate. According to some embodiments of the invention, the precipitant comprises aqueous ammonia. According t