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CN-121988359-A - CO (carbon monoxide)2High-efficiency catalyst for preparing long-chain olefin by hydrogenation and preparation method and application thereof

CN121988359ACN 121988359 ACN121988359 ACN 121988359ACN-121988359-A

Abstract

The invention discloses a high-efficiency catalyst for preparing long-chain olefin by CO 2 hydrogenation and a preparation method and application thereof, belonging to the technical field of preparation and application of CO 2 hydrogenation catalysts. The catalyst consists of active metal, a structure auxiliary agent and an alkali metal auxiliary agent, wherein the active metal is dispersed in the carrier structure auxiliary agent by adopting a precipitation method in the preparation process, and the alkali metal is uniformly loaded on the structure auxiliary agent and the active metal by adopting an impregnation method. The catalyst with smaller size and uniform particles is prepared by utilizing different precipitation methods, the adsorption and activation capacity of the catalyst to carbon dioxide can be effectively improved, the electron density of active metal in the catalyst is improved, and further, a reaction intermediate can be effectively adsorbed on the catalyst in the reaction process, so that the catalyst is coupled into a long-chain product, and the catalyst has excellent chain growth capacity, high long-chain olefin selectivity and catalytic stability, is suitable for industrial application, and has wide application prospect.

Inventors

  • LIU XIAOHAO
  • FAN ZHAOBO
  • Li Zhangshi
  • HE HUANHUAN
  • LI YUFENG
  • LI QIANG
  • LIU BING

Assignees

  • 江南大学

Dates

Publication Date
20260508
Application Date
20260109

Claims (10)

  1. 1. A method for preparing a catalyst for preparing long-chain olefin by hydrogenating CO 2 , which is characterized by comprising the following steps: (1) Sequentially adding active metal, a structure auxiliary agent and a precipitant into water at room temperature, stirring and dissolving, standing and aging, wherein the precipitant comprises any one of sodium carbonate, sodium bicarbonate, sodium hydroxide, urea and ammonia water; (2) Filtering the aged suspension in the step (1), collecting precipitate, washing and drying to obtain solid; (3) Immersing the solid obtained in the step (2) in an alkali metal salt solution, and carrying out alternating operation of stirring and standing to obtain slurry; (4) And (3) evaporating, drying and grinding the slurry obtained in the step (3) in vacuum, transferring the slurry into a muffle furnace, and roasting to obtain the catalyst.
  2. 2. The method of claim 1, wherein the active metal of step (1) comprises one or more of an iron salt, a zinc salt, and a copper salt.
  3. 3. The method of claim 1, wherein the construction aid of step (1) comprises one or more of Zn(NO 3 ) 2 ·6H 2 O,Mn(NO 3 ) 2 ·4H 2 O,Mg(NO 3 ) 2 ·6H 2 O,SiO 2 ,Al 2 O 3 ,ZrO 2 .
  4. 4. The method of claim 1, wherein the molar ratio of the active metal to the structure aid in step (1) is 1-5:1-3.
  5. 5. The method of claim 1, wherein the step (4) further comprises immersing the catalyst in a solution containing copper ions after grinding, wherein the mass fraction of copper ions is 10-15%, the time is 1-3 hours, and then taking out the catalyst, drying the catalyst, transferring the catalyst into a muffle furnace, and roasting the catalyst.
  6. 6. The catalyst prepared by the method of any one of claims 1 to 5.
  7. 7. The use of the catalyst of claim 6 in the hydrogenation of CO 2 to produce long chain olefins.
  8. 8. A method for preparing long-chain olefin by catalyzing CO 2 hydrogenation based on the catalyst of any one of claims 1-5 is characterized by comprising the steps of mixing the catalyst of any one of claims 1-5 with quartz sand, placing the mixture in a fixed bed reactor, purging a fixed bed with inert gas, reducing the mixture with pure hydrogen at 300-500 ℃ under normal pressure, cooling the mixture to 280-360 ℃, displacing the hydrogen in the fixed bed by using the reaction gas of CO 2 /H 2 , and pressurizing the reaction gas to 0.5-5 Mpa for reaction.
  9. 9. A method for increasing the conversion of CO 2 in a CO 2 hydrogenation reaction, the method comprising: Mixing the catalyst according to any one of claims 1-5 with quartz sand, placing the mixture in a fixed bed reactor, purging the fixed bed with inert gas, reducing the mixture with pure hydrogen at 300-500 ℃ under normal pressure, cooling the mixture to 280-360 ℃, displacing the hydrogen in the fixed bed by using the reaction gas of CO 2 /H 2 , and pressurizing the reaction gas to 0.5-5 Mpa for reaction.
  10. 10. A method for increasing the selectivity of long chain olefins in a CO 2 hydrogenation reaction, the method comprising the steps of: Mixing the catalyst according to any one of claims 1-5 with quartz sand, placing the mixture in a fixed bed reactor, purging the fixed bed with inert gas, reducing the mixture with pure hydrogen at 300-500 ℃ under normal pressure, cooling the mixture to 280-360 ℃, displacing the hydrogen in the fixed bed by using the reaction gas of CO 2 /H 2 , and pressurizing the reaction gas to 0.5-5 Mpa for reaction.

Description

Efficient catalyst for preparing long-chain olefin through CO 2 hydrogenation and preparation method and application thereof Technical Field The invention relates to a high-efficiency catalyst for preparing long-chain olefin by CO 2 hydrogenation, a preparation method and application thereof, belonging to the technical field of preparation and application of CO 2 hydrogenation catalysts. Background Long chain alpha-olefins (C≥4 and double bond at chain end) are irreplaceable intermediates for the synthesis of high-end polyolefins (LLDPE, HDPE comonomer), synthetic lubricating oils (PAO), detergent alcohols and oilfield chemicals, the annual demand has broken through 600 ten thousand tons and has been continuously rising at annual speeds of over 5%. However, the external dependence of C6-C10 alpha-olefins is higher than 80% for a long time, and the price of high-end brands remains in the range of 1.8-2.2 ten thousand yuan/ton throughout the year. The traditional production route comprises ethylene selective oligomerization, fischer-Tropsch wax high-temperature pyrolysis and alkane dehydrogenation, and has the common characteristics of high petroleum inlet and olefin outlet, high carbon emission cost, and high crude oil resource fluctuation and olefin separation energy consumption, so that a non-fossil alternative route based on CO 2 is needed in the industry. The CO 2 obtained by directly capturing industrial tail gas or air is directly hydrogenated and converted into long-chain alpha-olefin, so that the carbon circulation can be closed, renewable green hydrogen can be stored in the form of high-energy density liquid chemicals, and the carbon reduction and efficiency improvement dual values are achieved. The CO 2 molecule has a symmetrical linear structure and C=O bond energy of 799 kJ mol -1, the thermodynamic stability is extremely high, the triple energy barrier of activation-coupling-chain growth is needed to be crossed for converting the CO 2 molecule into long-chain olefin containing C=C bond, and the product selectivity control difficulty is far greater than that of the industrialized CO 2 methanol preparation or CH 4 preparation process. The strategies reported in the current literature for preparing olefins by CO 2 hydrogenation are mainly divided into two parts: (1) The methanol-mediated route (CO 2→ CH3 OH- & gt olefin) adopts metal oxide (In-Zr, cu-Zn) to be cascaded with SAPO-34 or ZSM-5 molecular sieve, the product is mainly C 2–C4 low-carbon olefin, the selectivity of long-chain olefin is less than 10%, and the high Wen Liyu olefin is generated but the methanol synthesis is inhibited, so that obvious thermodynamic-kinetic contradiction exists; (2) The reverse water gas shift and Fischer-Tropsch synthesis route (CO 2 -CO-long chain hydrocarbon, CO 2 -FTS for short) completes the C-O fracture and the C-C coupling on the Fe or Co-based catalyst once, the carbon number of the product is subject to Anderson-Schulz-Flory (ASF) distribution, 30-60% of C6 + hydrocarbon can be obtained by regulating and controlling the chain growth probability alpha, and then the alpha-olefin can be enriched through secondary cracking or molecular sieve shape selection. The second route is high in thermodynamic matching degree and is easier to break through the limit of carbon number, but the core contradiction is that the traditional Fe-based FTS catalyst has low CO 2 conversion rate (< 35%), the ASF distribution causes coexistence of alkane and alkene, the single pass yield of long-chain alpha-alkene is generally <15%, and meanwhile, the byproduct CO and CH 4 increase the energy consumption for subsequent separation. Therefore, the development of a novel catalytic material capable of achieving double advantages of high CO 2 conversion rate and high alpha-olefin selectivity becomes a key for breaking through the technical and economic balance point. In recent years, the academic world generally adopts an electronic auxiliary agent-structural auxiliary agent-carrier cooperative strategy to directionally improve the Fe-based catalyst, wherein alkali metals such as Na, K and the like can promote the active phase proportion of Fe 5C2/Fe7C3 and inhibit the side reaction of methane, zn and Mn can form spinel or oxygen vacancies to strengthen CO 2 adsorption and dissociation, and novel carriers such as carbon nano tubes, high-entropy oxides, layered Double Hydroxides (LDH) and the like inhibit iron particle sintering through a finite field effect, so that the selectivity of olefin is improved to more than 65%. However, the existing prepared catalyst has poor stability and service life of <100 h, and limits the use of the catalyst in industrial scale-up production. Disclosure of Invention Aiming at the defects existing in the prior art, the invention aims to provide a high-efficiency catalyst for preparing long-chain olefin by CO 2 hydrogenation, a preparation method and application thereof, and the catalyst can realize the h