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CN-122010140-A - Binder-free MCM-22 molecular sieve and preparation method and application thereof

CN122010140ACN 122010140 ACN122010140 ACN 122010140ACN-122010140-A

Abstract

The invention provides a binder-free MCM-22 molecular sieve, a preparation method and application thereof. Wherein the micropore specific surface area of the binderless MCM-22 molecular sieve is A m 2 /g, the total specific surface area of the binderless MCM-22 molecular sieve is B m 2 /g, and the relation between A and B is 50% or less (A/B) x 100% or less than 90%. The MCM-22 molecular sieve of the invention has large specific surface area, high crystallinity and mechanical strength of more than 80N/cm, is an MWW molecular sieve with a lamellar structure, and has good application prospect in the field of catalysis or adsorption.

Inventors

  • SHANG CHENGCHENG
  • WANG DEJU
  • REN JIE
  • QI SHENGDONG
  • CONG WENJIE
  • ZHU ZHIYAN

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
20260512
Application Date
20241108

Claims (10)

  1. 1. The binderless MCM-22 molecular sieve has a micropore specific surface area of A m 2 /g, a total specific surface area of B m 2 /g, and A and B satisfy the following relation of 50% to less than (A/B) multiplied by 100% to less than 90%.
  2. 2. The binderless MCM-22 molecular sieve according to claim 1, 200.Ltoreq.A≤500, and/or 400.Ltoreq.B≤550, and/or 50%≤(A/B)×100%≤80%。
  3. 3. The binderless MCM-22 molecular sieve according to claim 1 or 2, wherein the crystals of the binderless MCM-22 molecular sieve have a platelet morphology, preferably the platelet morphology comprises an interlaced platelet morphology, and/or The binder-free MCM-22 molecular sieve has a crystal thickness of 5nm to 20nm, and/or The binder-free MCM-22 molecular sieve crystals have a length of 100nm to 500nm, preferably 200nm to 500nm, and/or The width of the crystal of the MCM-22 molecular sieve is 100nm-500nm.
  4. 4. The binderless MCM-22 molecular sieve according to any one of claims 1 to 3, wherein the binderless MCM-22 molecular sieve has a total pore volume of 0.3cm 3 /g-0.5cm 3 /g, and/or The binderless MCM-22 molecular sieve has a micropore volume of 0.15cm 3 /g-0.3cm 3 /g, and/or The binderless MCM-22 molecular sieve has a mechanical strength of 80N/cm to 300N/cm, and/or The SiO 2 /Al 2 O 3 molar ratio of the binderless MCM-22 molecular sieve is 15-100.
  5. 5. A method for preparing a binderless MCM-22 molecular sieve, comprising: S1, mixing a mixture comprising a silicon source, an aluminum source, an alkali source, a seed crystal, an optional pore-forming agent and an extrusion aid, a template agent and a solvent, and crystallizing to obtain a crystallized product; s2, roasting the crystallized product; Preferably, the temperature of the calcination treatment is 400-650 ℃, and/or The roasting treatment time is 2-6 h.
  6. 6. The preparation method according to claim 5, characterized in that the preparation method comprises the steps of: A, performing first roasting treatment on a mixture comprising a silicon source, an aluminum source, an alkali source, a seed crystal, an optional pore-forming agent and an extrusion assisting agent to obtain a crystallization precursor; b, mixing the crystallization precursor with a template agent and a solvent, and then performing crystallization treatment to obtain a crystallization product; c, performing second roasting treatment on the crystallized product; Preferably, the temperature of the first firing treatment and the second firing treatment are each independently 400 ℃ to 650 ℃; Preferably, the temperature of the second calcination treatment is 500-650 ℃, and/or The time of the first roasting treatment and the second roasting treatment is 2h-6h respectively and/or The mechanical strength of the crystallization precursor is 120N/cm-300N/cm, and/or The atmosphere of the second roasting treatment is air, and/or Washing and drying the crystallized product before the second roasting treatment, and/or The crystallization treatment is carried out at a temperature of 130-160 ℃, preferably 140-150 ℃, and/or The crystallization treatment time is 24-120 h.
  7. 7. The method according to claim 5 or 6, wherein the silicon source is selected from one or more of silica gel powder, silica sol, white carbon black or water glass, and/or The aluminum source is selected from one or more of aluminum nitrate, aluminum sulfate, sodium aluminate or pseudo-boehmite, and/or The alkali source is NaOH and/or KOH, and/or The alkali source is calculated as OH - , the silicon source is calculated as SiO 2 , OH - /SiO 2 molar ratio=0.06-0.15, and/or The aluminum source is calculated as Al 2 O 3 , the silicon source is calculated as SiO 2 , the Al 2 O 3 /SiO 2 molar ratio=0.01-0.1, and/or The seed crystal is selected from MCM-22 molecular sieves, and the silicon-aluminum ratio of the seed crystal is 15-100 according to the mol ratio of SiO 2 to Al 2 O 3 ; Preferably, the silicon source is calculated as SiO 2 , seed/SiO 2 molar ratio = 0.01-0.15.
  8. 8. The method according to any one of claims 5to 7, wherein the pore-forming agent is selected from one or more of polyethylene glycol, polyvinyl alcohol or activated carbon powder, and/or The extrusion aid is selected from one or more of sesbania powder, methylcellulose, hydroxypropyl cellulose or sesbania gum, and/or The mass ratio of the pore-forming agent to the mixture is 0.001-0.01, and/or The mass ratio of the extrusion aid to the mixture is 0.001-0.02.
  9. 9. The preparation method according to any one of claims 6 to 8, wherein the template agent is selected from hexamethyleneimine, preferably the total silicon content of the crystallization precursor is calculated as SiO 2 , the molar ratio of the template agent to SiO 2 = 0.1-0.4, preferably 0.1-0.25, more preferably 0.15-0.25, and/or the solvent is selected from water, and/or The total silicon content of the crystallization precursor is calculated by SiO 2 , and the mol ratio of the solvent to SiO 2 is 0.5-5, preferably 0.5-2.
  10. 10. Use of the binderless MCM-22 molecular sieve of any one of claims 1 to 4 or prepared by the method of preparation of any one of claims 5 to 9 in the field of catalysis or adsorption.

Description

Binder-free MCM-22 molecular sieve and preparation method and application thereof Technical Field The invention belongs to the technical field of molecular sieves, and particularly relates to an MCM-22 molecular sieve without a binder, and a preparation method and application thereof. Background MCM-22 molecular sieves are a class of molecular sieve materials based on MWW structure lamellae, which were synthesized by researchers from Mobil in 1990. The catalyst has good thermal stability, hydrothermal stability and unique acidity, and has two pore channels of a twelve-membered ring and a ten-membered ring, so that the diffusion performance can be improved, the catalytic activity is improved, and the catalyst has important application in industrial catalysis. In 1995, exxon Mobil developed a liquid phase alkylation EBMaxSM process based on MCM-22 molecular sieve catalyst for ethylbenzene synthesis. The Mobil-Badger process uses MCM-22 molecular sieve as a catalyst for synthesizing cumene. The middle petrochemical (Shanghai) petrochemical institute Co.Ltd develops energy-saving type low-benzene-ratio liquid phase alkylation ethylbenzene EBC series catalysts based on ultra-thin layered MWW molecular sieves. The MCM-22 synthesis method comprises a hydrothermal synthesis method and a vapor phase synthesis method, and most of the prior art adopts the hydrothermal synthesis method. The hydrothermal synthesis method can be divided into dynamic hydrothermal synthesis method and static hydrothermal synthesis method, and the difference between the two methods is whether the gel mother solution is subjected to rotary stirring in the crystallization process. Whereas vapor phase synthesis is a method disclosed in Xu Wen for synthesizing zeolites in which the vapor is not in direct contact with the solid phase gel. The vapor phase synthesis method has the greatest advantages of small template dosage, high solid yield, avoiding the dilution effect of mother liquor, reducing the emission of three wastes, and successfully synthesizing molecular sieves with various structures such as MFI, MOR, BEA, FER, MWW and the like by using the method at present. However, the molecular sieve products prepared by the conventional method are generally in a powder state, and when the molecular sieve products are used as a fixed bed catalyst or an adsorbent, an inert binder is added for molding, so that the molecular sieve products have certain mechanical strength, and the binder generally reduces the specific surface area of the catalyst or the adsorbent and reduces the active sites. The vapor phase synthesis method is a technology for preparing a non-binder molecular sieve, liu Xingsheng and the like report a preparation method of a non-binder MCM-22 zeolite particle catalyst, and mainly refers to the vapor phase synthesis method, silicon sources, aluminum sources and alkali are directly molded to prepare silica-alumina gel particles, the silica-alumina gel particles are placed on a bracket in a polytetrafluoroethylene reaction kettle, a certain amount of mixed solution of template agent HMI (hexamethyleneimine) and deionized water is weighed and placed at the bottom of the reaction kettle, and the product can be obtained after crystallization reaction, washing, filtering, drying and roasting. However, when the MCM-22 molecular sieve with large specific surface area is obtained by the method, the crystallization time is 168 hours, the addition amount of the template agent is large, the molar ratio of HMI/SiO 2 is at least 0.3, and the proportion of the micropore specific surface area is only 58%. CN107511174a discloses a method for preparing a binderless MWW structure molecular sieve catalyst, which prepares the binderless MWW structure molecular sieve by converting the binder in the MWW structure molecular sieve catalyst precursor into the MWW molecular sieve by means of acid. The HMI/SiO 2 molar ratio of the method is 0.5, the crystallization time is 5 days, the method is relatively long, and the steps are relatively complex. CN103771435A discloses a method for synthesizing MCM-22 molecular sieve, under the condition of hydrothermal crystallization, using two template agents of hexamethyleneimine and aniline, in which the mole ratio of hexamethyleneimine and aniline is less than 1.2, and said method reduces the consumption of hexamethyleneimine. The method is to hydrothermally synthesize the synthesized molecular sieve product in a powder state. The price of the template agent HMI required by the preparation of the MCM-22 molecular sieve at present is 5-10 ten thousand yuan/ton, the cost of silicon aluminum is less than 1 ten thousand per ton, the template agent occupies larger cost of the molecular sieve, the synthesis time is mostly more than 5 days, and the energy consumption cost is higher. Therefore, there is a need to find a method for preparing MCM-22 molecular sieves that can reduce the amount of template agent used, reduce synth