Solvent volatilization self-assembly method used for preparing multistage-channel SAPO-34 and SAPO-18 molecular sieves

Abstract

The invention discloses a method for preparing multistage-channel SAPO-n (n=34, 18) through solvent volatilization. According to the invention, a zeolite template agent is added into a mixed solution of an aluminum source, a silicon source, and a phosphorus source; stirring and a reaction are sufficiently carried out; the solution is completely delivered into a culture dish, and is air-dried into gel; under the effect of steam formed by water added into an autoclave, the gel is subjected to hydrothermal synthesis; powder converted from the gel is subjected to a heat treatment under high temperature, such that the multistage-channel SAPO-n zeolite is formed. The method provided by the invention has the advantages of simple process, easy control, easy realization, low cost, and environment friendliness.

Description

technical field [0001] The invention relates to a preparation method of a multi-stage pore silicon-phosphorus-aluminum molecular sieve with adjustable pore size, in particular to processes such as preparation of a precursor, volatilization of a solvent, preparation of a gel, solvothermal treatment of the gel, and heat treatment of a sample. . Background technique [0002] Zeolite and zeolite molecular sieves have become important catalytic materials in petrochemical industry. In addition to silica-alumina zeolites, SAPO-n molecular sieves, such as SAPO-34 and SAPO-18, have high catalytic activity and selectivity in methanol to light olefins. The particle size of the molecular sieve obtained by the traditional preparation method is relatively large, which has a serious limitation on the catalytic life of the molecular sieve. The introduction of the concept of multi-stage pore molecular sieve shortens the molecular diffusion distance, makes it easier for the reaction product...

AI Technical Summary

Problems solved by technology

However, usually its preparation method is cumbersome and the preparation cost is high, which greatly limits the industrialization of multi-stage pore molecular sieves.

The traditional method of dealumination and desiliconization will reduce the crystallinity of zeolite, and the pore connectivity of zeolite is poor, the improvement of diffusion resistance is very limited, and it cannot be extended to non-zeolite molecular sieves such as SAPO-n

Although carbon templates can obtain multi-level channel single crystals, the templates are expensive and not easy to obtain, which limits their development.

The recently developed silane method uses TPHAC (hexadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride), although it can obtain multi-stage molecular sieves with better morphology and performance. , but TPHAC itself is expensive but limits the industrial promotion of this method

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