Search

CN-121990589-A - Method for synthesizing hierarchical pore ZSM-5 molecular sieve with assistance of metal salt

CN121990589ACN 121990589 ACN121990589 ACN 121990589ACN-121990589-A

Abstract

The invention belongs to the technical field of molecular sieves and porous materials, and particularly relates to a method for synthesizing a multistage pore ZSM-5 molecular sieve with the assistance of metal salts. Mixing metal salt, water and a synthetic mother solution of the ZSM-5 molecular sieve, performing hydrothermal crystallization, separating, washing, drying and calcining a crystallized product to obtain the multistage hole ZSM-5 molecular sieve. Compared with the prior art, the invention uses metal salt to replace long-chain organic matters or carbon materials as the hierarchical pore guiding agent, and can effectively reduce the production cost of the hierarchical pore ZSM-5. Meanwhile, the multistage pore degree of ZSM-5 can be regulated and controlled by the addition proportion of metal salt, so that the multistage pore ZSM-5 molecular sieve has wide application prospect in the fields of catalysis, separation and the like.

Inventors

  • PAN XIULIAN
  • DING YILUN
  • Miao dengyun
  • BAO XINHE

Assignees

  • 中国科学院大连化学物理研究所

Dates

Publication Date
20260508
Application Date
20241108

Claims (6)

  1. 1. A method for synthesizing a hierarchical pore ZSM-5 molecular sieve with the assistance of metal salt is characterized in that metal salt, water and a synthesis mother solution of the ZSM-5 molecular sieve are mixed, hydrothermal crystallization is carried out, and a crystallization product is separated, washed, dried and then calcined to obtain the hierarchical pore ZSM-5 molecular sieve; the metal salt comprises at least one of titanium salt, tin salt, gallium salt, vanadium salt, copper salt, zirconium salt, chromium salt, nickel salt, niobium salt, yttrium salt and scandium salt.
  2. 2. The method for synthesizing the hierarchical pore ZSM-5 molecular sieve according to claim 1, wherein the synthesis mother liquor of the ZSM-5 molecular sieve consists of a silicon source, an aluminum source, an organic template agent R and an alkali source, wherein the silicon source is selected from at least one of silicic acid, silica gel, silica sol, tetraalkyl silicate, water glass and silicon dioxide, the aluminum source is selected from at least one of aluminum hydroxide, sodium metaaluminate, aluminum nitrate, aluminum chloride, aluminum isopropoxide, aluminum sulfate, pseudo-boehmite, kaolin and montmorillonite, the organic template agent R is selected from at least one of tetrapropylammonium hydroxide, tetrapropylammonium bromide and tetrapropylammonium chloride, and the alkali is selected from at least one of tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, hydroxide of alkali metal and hydroxide of alkaline earth metal.
  3. 3. The method for synthesizing the hierarchical pore ZSM-5 molecular sieve according to claim 1 wherein the molar ratio of the silicon source, the aluminum source, the alkali, the organic template R, the metal salt M and the water is ：SiO 2 :Al 2 O 3 :OH - :R:M:H 2 O＝1:(0.00001-0.4):(0.01-1):(0.01-1):x:(1-200),0<x<0.5.
  4. 4. The method for synthesizing the hierarchical pore ZSM-5 molecular sieve according to claim 1, wherein the hydrothermal crystallization condition is a crystallization temperature of 130-190 ℃ and a crystallization time of 3-240 hours.
  5. 5. The method for synthesizing the hierarchical pore ZSM-5 molecular sieve with the assistance of metal salts according to claim 1, wherein the calcination temperature is 400-600 ℃ and the calcination time is 2-10 hours.
  6. 6. A multi-pore ZSM-5 molecular sieve prepared according to any of claims 1-5, characterized in that the ratio of the acid sites on the outer surface to the total acid sites, measured by pyridine adsorption infrared and 2, 6-di-tert-butylpyridine adsorption infrared, is higher than 10%.

Description

Method for synthesizing hierarchical pore ZSM-5 molecular sieve with assistance of metal salt Technical Field The invention belongs to the technical field of molecular sieves and porous materials, and particularly relates to a method for synthesizing a multistage pore ZSM-5 molecular sieve with the assistance of metal salts. Background Molecular sieves are a class of microporous materials that are widely used in industrial catalytic processes, with ZSM-5 molecular sieves being a typical representation thereof. ZSM-5 molecular sieve was synthesized for the first time in 1972 by Mobil company (US 4954325), and according to the published result of International molecular sieve Association (International Zeolite Association, IZA), ZSM-5 molecular sieve belongs to MFI topology structure, has three-dimensional ten-membered ring channel structure, and the diameter of channel is 0.5-0.6nm. ZSM-5 has regular and ordered microporous channels and acidic active centers in the channels, so that the ZSM-5 has wide application in catalytic reaction and separation, such as hydrocracking, alkylation, isomerization and the like. However, the smaller size of the microporous channels increases the molecular diffusion resistance, which results in side reactions, and reduces the performance and life of the catalyst. Therefore, it is important to prepare ZSM-5 molecular sieve containing multiple levels of pores. Methods for preparing hierarchical pore ZSM-5 have been conventionally used, including a post-treatment method and a template method. For example, J.P derez-RamI rez et al treat ZSM-5 molecular sieves with NaOH solution (J.Phy. Chem. C,2011,115:1, 4193-14203), but the product yield is low and the crystallinity is poor. The template rules include hard template methods and soft template methods. The hard template method is to use various carbon materials as templates, directly grow molecular sieves on the surfaces of the carbon materials, and remove the templates (Inorg.Chem.2000,39,2279-2283;Microporous Mesoporous Mater.2003,65,59-75;Chem.Mater.2004,16,3168-3175). by calcination after crystallization is completed, and the soft template method is to use long-chain organic matters as soft template synthesis, such as double quaternary ammonium group surfactant C 22-6-6(OH)2 (Nature 2009,461,246-249), CTAB (Catal. Commun.2011,12, 1201-1205), silanized seed crystal (chem. Mater.2009,21, 641-654) and the like. The template method has the problem of relatively high cost and large industrialization difficulty. Therefore, it is important to develop a strategy for synthesizing the hierarchical pore ZSM-5 molecular sieve with low cost and easy implementation. Disclosure of Invention Aiming at the problems, the invention provides a method for synthesizing the hierarchical pore ZSM-5 molecular sieve by using metal salt as an auxiliary component, which is simple, convenient and economic and has important significance for regulating the morphology, catalysis and separation performance of the molecular sieve. In order to achieve the above object, the technical scheme of the present invention is as follows: The invention provides a method for synthesizing a hierarchical pore ZSM-5 molecular sieve by using metal salt, which comprises the steps of mixing metal salt, water and a synthesis mother solution of the ZSM-5 molecular sieve, carrying out hydrothermal crystallization, separating, washing, drying and calcining a crystallized product to obtain the hierarchical pore ZSM-5 molecular sieve, wherein the metal salt comprises at least one of titanium salt, tin salt, gallium salt, vanadium salt, copper salt, zirconium salt, chromium salt, nickel salt, niobium salt, yttrium salt and scandium salt. In the technical scheme, the synthesis mother liquor of the ZSM-5 molecular sieve is further composed of a silicon source, an aluminum source, an organic template agent R and an alkali source, wherein the silicon source is at least one of silicic acid, silica gel, silica sol, tetraalkyl silicate, sodium silicate, water glass and silicon dioxide, the aluminum source is at least one of aluminum hydroxide, sodium metaaluminate, aluminum nitrate, aluminum chloride, aluminum isopropoxide, aluminum sulfate, pseudo-boehmite, kaolin and montmorillonite, the organic template agent R is at least one of tetrapropylammonium hydroxide, tetrapropylammonium bromide and tetrapropylammonium chloride, and the alkali is at least one of alkali metal hydroxide, alkaline earth metal hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide. In the above technical solution, further, the titanium salt includes titanium tetrachloride, tetrabutyl titanate, tetraethyl titanate, the tin salt includes tin tetrachloride, sodium stannate, and tin dioxide, the gallium salt includes gallium nitrate, gallium oxide, and gallium chloride, the vanadium-containing salt includes vanadyl sulfate, and ammonium metavanadate, the copper salt includes copper acetylacetonate, cop