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CN-118162202-B - Catalyst for preparing olefin by catalytic cracking and preparation method and application thereof

CN118162202BCN 118162202 BCN118162202 BCN 118162202BCN-118162202-B

Abstract

The invention discloses a catalyst for preparing olefin by catalytic pyrolysis, a preparation method and application thereof, wherein the catalyst comprises a first active center and a second active center, and the first active center is a zinc-modified ZSM-5 molecular sieve; the second active center is silver modified beta molecular sieve. The preparation method comprises the steps of (1) preparing a zinc modified ZSM-5 molecular sieve, (2) preparing a silver modified beta molecular sieve, and (3) fully mixing the zinc modified ZSM-5 molecular sieve obtained in the step (1) and the silver modified beta molecular sieve obtained in the step (2), and further forming to obtain the catalyst. The catalyst provided by the invention is suitable for the cracking reaction of C5-C10 normal paraffins and the reaction of preparing low-carbon olefins by cracking naphtha, and shows higher low-carbon olefin yield and selectivity.

Inventors

  • LIU JIA
  • ZHOU MINGDONG
  • SONG ZHAOYANG
  • XU HUIQING
  • LI SIJIE

Assignees

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

Dates

Publication Date
20260505
Application Date
20221209

Claims (16)

  1. 1. The catalyst for preparing olefin by catalytic pyrolysis comprises a first active center and a second active center, wherein the first active center is a zinc-modified ZSM-5 molecular sieve, the second active center is a silver-modified beta molecular sieve, the content of ZnO is 0.1% -5.0%, the content of Ag 2 O is 0.1% -5.0%, the content of ZSM-5 molecular sieve is 5% -80%, and the content of beta molecular sieve is 10% -94.8% based on the weight percentage of the catalyst.
  2. 2. The catalyst for preparing olefin by catalytic pyrolysis according to claim 1, wherein the catalyst comprises, by weight, 0.5% -3.0% of ZnO, 0.3% -2.0% of Ag 2 O, 20% -60% of ZSM-5 molecular sieve and 35% -75% of beta molecular sieve.
  3. 3. The catalyst for preparing olefin by catalytic pyrolysis according to claim 1, wherein the ZSM-5 molecular sieve is a hydrogen molecular sieve with a silicon-aluminum molar ratio of 50-1000.
  4. 4. The catalyst for preparing olefin by catalytic pyrolysis according to claim 1, wherein the beta molecular sieve is a hydrogen molecular sieve, and the molar ratio of silicon to aluminum is 10-100.
  5. 5. A process for preparing a catalyst for the catalytic cracking of olefins according to any of claims 1 to 4, comprising the steps of: (1) Preparing a zinc modified ZSM-5 molecular sieve, mixing a zinc precursor with the ZSM-5 molecular sieve, and drying and roasting to obtain the zinc modified ZSM-5 molecular sieve; (2) Preparing a silver modified beta molecular sieve, mixing a silver precursor with the beta molecular sieve, and then drying and roasting to obtain the silver modified beta molecular sieve; (3) And (3) fully mixing the zinc modified ZSM-5 molecular sieve obtained in the step (1) and the silver modified beta molecular sieve obtained in the step (2), and further forming to obtain the catalyst.
  6. 6. The method for preparing olefin catalyst by catalytic cracking according to claim 5, wherein the zinc precursor is soluble zinc-containing inorganic salt, and the soluble zinc-containing inorganic salt is one or more selected from zinc nitrate, zinc chloride and zinc sulfate.
  7. 7. The method for preparing olefin catalyst by catalytic cracking according to claim 6, wherein the soluble zinc-containing inorganic salt is zinc nitrate.
  8. 8. The method for preparing olefin catalyst by catalytic cracking according to claim 5, wherein the silver precursor is a soluble silver-containing inorganic salt compound.
  9. 9. The method for preparing an olefin catalyst by catalytic cracking according to claim 5 or 8, wherein the silver precursor is silver nitrate.
  10. 10. The method for preparing an olefin catalyst by catalytic cracking according to claim 5, wherein the mixing in the step (1) and the step (2) is at least one of kneading, dipping and spraying.
  11. 11. The method for preparing an olefin catalyst by catalytic cracking according to claim 5, wherein the mixing in the step (1) and the step (2) is performed by kneading.
  12. 12. The method for preparing an olefin catalyst by catalytic pyrolysis according to claim 5, wherein the drying and roasting operation conditions in the step (1) and the step (2) are the same or different, the drying temperature is 20-300 ℃, the drying time is 0.5-24 hours, the roasting temperature is 300-700 ℃, and the roasting time is 0.5-12 hours.
  13. 13. Use of the catalyst for preparing olefin by catalytic cracking according to any one of claims 1 to 4 or the catalyst for preparing olefin by catalytic cracking obtained by the preparation method according to any one of claims 5 to 12 for preparing light olefins.
  14. 14. A method for preparing low-carbon olefin by catalytic cracking of alkane, which comprises the steps of enabling alkane raw materials to enter a reactor to contact with a catalytic cracking olefin preparation catalyst for reaction, wherein the catalytic cracking olefin preparation catalyst adopts the catalytic cracking olefin preparation catalyst according to any one of claims 1-4 or adopts the catalytic cracking olefin preparation catalyst obtained by the preparation method according to any one of claims 5-12.
  15. 15. The method for preparing light olefins by catalytic cracking of alkane according to claim 14, wherein the alkane raw material is one or a mixture of several of C5-C9 normal alkanes.
  16. 16. The method for preparing light olefins by catalytic cracking of alkane according to claim 14, wherein the alkane raw material is n-heptane and/or n-octane.

Description

Catalyst for preparing olefin by catalytic cracking and preparation method and application thereof Technical Field The invention belongs to the technical field of petrochemical industry, relates to a catalytic material and a preparation method thereof, and in particular relates to a catalyst for preparing low-carbon olefin (including but not limited to ethylene, propylene and butylene) by pyrolysis and a preparation method thereof. Background The low-carbon olefin (ethylene, propylene and butylene) is an important organic chemical raw material, is a main raw material source for producing daily chemicals such as rubber, plastics and the like, and plays a very important role in petrochemical industry and daily life of people. The global propylene and ethylene demand in 2021 was 9100 and 21000 kilotons respectively, propylene/ethylene was 0.43, while the propylene and ethylene yields in the current year were only 0.35, with quite serious contradiction between supply and demand. It is predicted that future markets will increase propylene demand year by year at growth rates exceeding 6.5% and that the supply and demand gap problem will continue to be exacerbated. How to increase the yield of low-carbon olefin, especially propylene, so as to meet the market demand is the key point of research. At present, more than 95% of ethylene and more than 60% of propylene used worldwide come from steam cracking processes. The naphtha steam cracking technology has been developed for 70 years, the technology is quite mature, but because the hydrocarbon thermal cracking reaction follows a free radical reaction mechanism, the essential characteristic cannot be changed, so that the technology has a plurality of insurmountable defects, such as large energy consumption, unreasonable product distribution, difficult regulation (low propylene/ethylene ratio, more low added value products), low raw material utilization rate, large carbon oxide discharge amount and the like. Under the drive of the current energy-saving environment-friendly large situation and the contradiction between market supply and demand, the defects can severely limit the further popularization, application and development of the process. Compared with steam cracking, the naphtha catalytic cracking has the characteristics of mild operation conditions, high selectivity of high added value products, adjustable propylene/ethylene ratio and the like, is considered to be a steam cracking substitution process with great potential, and is attracting more and more attention by researchers. USP3767567 discloses a catalyst for preparing low-carbon olefin by naphtha pyrolysis, which comprises any one oxide (> 20wt%) in CaO, beO, srO and alumina as catalysts, naphtha with boiling point of 70-180 ℃ as raw materials, reaction temperature of 650-900 ℃ and water-oil ratio of 0.5-10, wherein CaO-Al 2O3 type catalyst is the best, the highest yield of ethylene in the product is 52.5%, and the propylene yield is 16.3%. US4705769 discloses a catalyst for preparing low-carbon olefin by butane pyrolysis, which adopts manganese oxide or ferric oxide as an active component, an oxide catalyst of rare earth element La and alkaline earth metal Mg is added, isobutane is adopted as a raw material, the reaction temperature is 700 ℃, the butane conversion rate is 80% by a fixed bed reactor, and the selectivity of ethylene and propylene is 34% and 20% respectively. And claims that the catalyst can be used in naphtha and fluidized bed reactors. CN103785454a discloses a catalytic cracking catalyst and a preparation method thereof. The catalyst comprises, by weight, 15% -65% of natural minerals, (b) 10% -30% of oxides and (c) 25% -75% of phosphorus-containing silicon-rich beta molecular sieves. The catalyst is used in the catalytic cracking process of naphtha and has higher yield of low-carbon olefin. CN102371172A discloses a catalyst for preparing olefin by catalytic cracking, which comprises, by weight, 15% -60% of kaolin, (2) 10% -30% of at least one selected from silicon oxide or aluminum oxide, (3) 0.5% -15% of at least one selected from phosphorus, rare earth or alkaline earth metal oxide, and (4) 25% -70% of ZSM-5 zeolite synthesized by adopting a guiding agent method, wherein the grain size of the ZSM-5 zeolite is 200-1000 nm. The catalyst is used for naphtha catalytic pyrolysis, and can obviously improve the conversion rate of naphtha and the yields of ethylene and propylene. CN101279285A discloses a catalyst for preparing low-carbon olefin by naphtha cracking, which comprises that a catalyst formed by loading at least one element of IVb group elements or VB group elements or oxides thereof in periodic table on a ZSM-5/mordenite intergrowth molecular sieve, a ZSM-5/beta zeolite intergrowth molecular sieve or a ZSM-5/Y zeolite intergrowth molecular sieve is used for preparing ethylene and propylene by naphtha catalytic cracking. In a fixed bed reactor, the reaction temperature is 600-700 ℃,