Method for synthesizing molecular sieve of ZSM-5 zeolite in small crystal grain

Abstract

This invention relates to a method for synthesizing ZSM-5 zeolite molecular sieve, especially a method for rapidly synthesizing ZSM-5 zeolite molecular sieve with small grains. The method comprises: (1) adjusting the pH value of a mixture of silicon source and deionized water with an acid solution, stirring for hydrolysis, and adding organic templating agent to obtain solution A; (2) dissolving aluminum source with deionized water to obtain solution B; (3) dropping solution B into solution A slowly, and adding molecular sieve seed crystal; (4) placing the mixture into a hydrothermal kettle, crystallizing, washing the product, centrifuging, drying and torrefying to obtain ZSM-5 zeolite molecular sieve with small grains. The method is simple and time efficient, and the obtained ZSM-5 zeolite molecular sieve has small and uniform grains.

Description

technical field [0001] The invention relates to a method for synthesizing a ZSM-5 zeolite molecular sieve, in particular to a method for rapidly synthesizing a small-grain ZSM-5 zeolite molecular sieve. Background technique [0002] The ZSM-5 zeolite molecular sieve (USP 3702886, 1972) invented by Mobil Petroleum Company of the United States has been widely used in petrochemical processes such as shape-selective catalysis, isomerization, disproportionation, and alkylation. However, due to its narrow pores and high diffusion resistance of reactants or products, zeolite catalytic materials are increasingly unable to meet the needs of more and more macromolecules and liquid phase reactions in the fields of fine chemicals, while small-grain zeolites are due to their outer surface. The increase increases the number of acid sites on the outer surface, and because the diffusion path on the inner surface is shortened, the catalytic activity is higher, and the efficiency of the catal...

AI Technical Summary

Problems solved by technology

ZSM-5 molecular sieves synthesized by conventional methods generally have larger crystal grains, and the grain size is generally about 2-5 μm. However, it is very difficult to synthesize ZSM-5 molecular sieves with small grains by conventional methods.

[0012] Existing methods for synthesizing small-grain ZSM-5 zeolite molecular sieves have their own disadvantages: either adding certain salts or other substances; or using expensive sodium-free reagents or organic templates, or needing to reduce crystallization temperature, prolong the crystallization time; or add surfactants; or use inert mesoporous materials as space-limited substances

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