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CN-121974371-A - Aluminum-rich Beta molecular sieve and in-situ synthesis method thereof

CN121974371ACN 121974371 ACN121974371 ACN 121974371ACN-121974371-A

Abstract

The invention provides an aluminum-rich Beta molecular sieve and an in-situ synthesis method thereof. The in-situ synthesis method of the aluminum-rich Beta molecular sieve comprises the steps of (1) mixing water, an alkali source, an aluminum source, an organic template agent and a liquid phase silicon source, performing closed crystallization to obtain crystallization mother liquor, (2) adding the water, the aluminum source, a solid phase silicon source and the alkali source into the crystallization mother liquor obtained in the step (1), mixing, performing closed crystallization to obtain an aluminum-rich Beta molecular sieve dispersion liquid, and (3) filtering, washing, ammonium exchanging, drying and roasting the aluminum-rich Beta molecular sieve dispersion liquid to obtain the aluminum-rich Beta molecular sieve, wherein the liquid phase silicon source comprises alkaline silica sol, and the solid phase silicon source comprises coarse silica gel. The in-situ synthesis method is not easy to generate mixed crystals and has low template agent dosage.

Inventors

  • CUI YAN
  • SHI DEJUN
  • WANG BODI
  • LI SHUAI
  • WU YUCHAO
  • WANG XIAOHUA
  • XIE YIN
  • GUO CHENGYU
  • YU HONGYUE
  • CHI KEBIN

Assignees

  • 中国石油天然气股份有限公司

Dates

Publication Date
20260505
Application Date
20241030

Claims (14)

  1. 1. An in situ synthesis method of an aluminum-rich Beta molecular sieve comprises the following steps: (1) Mixing water, an alkali source, an aluminum source, an organic template agent and a liquid phase silicon source, and performing closed crystallization to obtain a crystallized mother solution; (2) Adding water, an aluminum source, a solid-phase silicon source and an alkali source into the crystallization mother liquor obtained in the step (1), mixing, and performing closed crystallization to obtain an aluminum-rich Beta molecular sieve dispersion liquid; (3) Filtering, washing, ammonium exchanging, drying and roasting the aluminum-rich Beta molecular sieve dispersion liquid to obtain the aluminum-rich Beta molecular sieve; the liquid phase silicon source comprises an alkaline silica sol and the solid phase silicon source comprises coarse pore silica gel.
  2. 2. The in situ synthesis process according to claim 1, wherein in step (1), the liquid phase silicon source is finally added for mixing.
  3. 3. The in-situ synthesis method according to claim 1, wherein in the step (2), the crystallization mother liquor obtained in the step (1) is sequentially added and mixed in the order of water, aluminum source, solid phase silicon source and alkali source.
  4. 4. The in situ synthesis process according to claim 1, wherein in step (1), the crystallization is closed at 120-180 ℃ for 24-96 hours; And/or, in the step (2), the closed crystallization is carried out for 10-72 hours at the temperature of 110-160 ℃.
  5. 5. The in situ synthesis process according to claim 1, wherein the alkaline silica sol comprises sodium-type silica sol and/or ammonia-type silica sol.
  6. 6. The in situ synthesis process according to claim 1, wherein the coarse pore silica gel has a particle size of 50-500 mesh, an average pore diameter of 6-15nm and a specific surface area of 200-500m 2 /g.
  7. 7. The in situ synthesis process of claim 1, wherein the alkali source is calculated as M 2 O, the aluminum source is calculated as Al 2 O 3 , the liquid phase silicon source is calculated as SiO 2 , the organic template is calculated as cation, and the molar ratio of each raw material in step (1) satisfies one or a combination of two or more of the following molar ratios: Liquid phase silicon source, aluminum source=25-50; organic template agent, liquid phase silicon source=0.05-0.25; alkali source, liquid phase silicon source=0.03-0.20; water liquid phase silicon source = 12-50.
  8. 8. The in situ synthesis process according to claim 1, wherein the alkali source is calculated as M 2 O, the aluminum source is calculated as Al 2 O 3 , the solid phase silicon source is calculated as SiO 2 , and the molar ratio of each raw material in step (2) satisfies one or a combination of two or more of the following molar ratios: solid phase silicon source, aluminum source=30-60; Alkali source, solid phase silicon source=0.1-0.4; Water solid phase silicon source = 12-35.
  9. 9. The in situ synthesis process according to claim 1, wherein the molar ratio of the liquid phase silicon source to the solid phase silicon source is (1-15): 100, calculated as SiO 2 .
  10. 10. The in situ synthesis process of claim 1, wherein the alkali source in step (1) and step (2) comprises sodium hydroxide and/or potassium hydroxide.
  11. 11. The in situ synthesis process of claim 1, wherein the aluminum source in step (1) and step (2) comprises one or a combination of two or more of sodium metaaluminate, aluminum nitrate, aluminum sulfate.
  12. 12. The in situ synthesis process of claim 1, wherein the organic template comprises tetraethylammonium hydroxide and/or tetraethylammonium bromide.
  13. 13. An aluminum-rich Beta molecular sieve made by the in situ synthesis method of any one of claims 1-12.
  14. 14. The aluminum enriched Beta molecular sieve of claim 13, wherein the aluminum enriched Beta molecular sieve has a silica to alumina ratio of 9-15.

Description

Aluminum-rich Beta molecular sieve and in-situ synthesis method thereof Technical Field The invention belongs to the field of molecular sieve material synthesis, and particularly relates to an aluminum-rich Beta molecular sieve and an in-situ synthesis method thereof. Background Beta molecular sieves are first described in USP3308069. With the understanding of the crystal structure of beta molecular sieve, the synthesis and catalytic performance research of beta molecular sieve is rapidly developed, and the excellent catalytic performance of beta molecular sieve in numerous catalytic reactions of petroleum refining and petrochemical processes such as hydrogenation, cracking, isomerization, alkylation, olefin hydration, dewaxing and photocatalysis are reported in a long-felt way. Because it is the only high-silicon zeolite with three-dimensional twelve-membered ring pore canal system in the world, the silicon-aluminum ratio range (oxide molar ratio) which can be directly synthesized is generally 20 to positive infinity. Aluminum-rich Beta molecular sieves with lower silica to alumina ratios are difficult to obtain by direct synthesis. CN1086792a discloses a method for synthesizing Beta molecular sieve by using guide agent induction, in the crystallization process, firstly preparing guide agent, then adding guide agent into crystallization mother liquor to successfully synthesize Beta molecular sieve whose silicon-aluminum ratio is as low as 11.6, but the silicon source required to be used is high-activity white carbon black, and the problems of high cost and low yield are existed. CN101249968B discloses a method for synthesizing Beta molecular sieve by solid phase molecular sieve seed crystal induction, in the crystallization process, no organic template agent participates in reaction, so that the product can possess a smooth pore canal without roasting template agent, and the molecular sieve is also aluminum-rich molecular sieve, but the silicon source required to be used is also high-activity white carbon black. Disclosure of Invention In order to solve the problems, the invention aims to provide an aluminum-rich Beta molecular sieve and an in-situ synthesis method thereof, wherein the in-situ synthesis method is not easy to generate mixed crystals and has low template dosage. In order to achieve the above purpose, the invention provides an in-situ synthesis method of an aluminum-rich Beta molecular sieve, which comprises the following steps: (1) Mixing water, an alkali source, an aluminum source, an organic template agent and a liquid phase silicon source, and performing closed crystallization to obtain a crystallized mother solution; (2) Adding water, an aluminum source, a solid-phase silicon source and an alkali source into the crystallization mother liquor obtained in the step (1), mixing, and performing closed crystallization to obtain an aluminum-rich Beta molecular sieve dispersion liquid; (3) And filtering, washing, ammonium exchanging, drying and roasting the aluminum-rich Beta molecular sieve dispersion liquid to obtain the aluminum-rich Beta molecular sieve, wherein the liquid phase silicon source comprises alkaline silica sol, and the solid phase silicon source comprises coarse pore silica gel. According to a specific embodiment of the present invention, preferably, in step (1), the liquid phase silicon source is finally added for mixing. According to a specific embodiment of the present invention, preferably, in the step (2), the crystallization mother liquor obtained in the step (1) is sequentially added and mixed in the order of water, aluminum source, solid phase silicon source, and alkali source. According to a specific embodiment of the present invention, preferably, the alkaline silica sol comprises a sodium silica sol and/or an ammonia silica sol, more preferably an ammonia silica sol. The present invention is not limited to the effective silica content of the alkaline silica sol, and it is preferable that the effective silica content of the alkaline silica sol is 20 to 45wt% according to the specific embodiment of the present invention. According to a specific embodiment of the present invention, it is preferable that the particle size of the coarse porous silica gel is 50 to 500 mesh, the average pore diameter is 6 to 15nm, the specific surface area is 200 to 500m 2/g, and more preferable that the particle size of the coarse porous silica gel is 100 to 300 mesh, the average pore diameter is 8to 12nm, and the specific surface area is 250 to 400m 2/g. According to a specific embodiment of the present invention, preferably, the alkali source is calculated as M 2 O, the aluminum source is calculated as Al 2O3, the liquid phase silicon source is calculated as SiO 2, the organic template is calculated as cation R +, and the molar ratio of each raw material in the step (1) satisfies one or a combination of two or more of the following molar ratios: Liquid phase silicon source, aluminum sourc