Preparation method of HZSM-5@SiO2 composite molecular sieve with high mesoporous degree

Abstract

The invention provides a preparation method of an HZSM-5@SiO2 composite molecular sieve with a high mesoporous degree. The method comprises the following steps of: mixing a mixed solution of an alkalimetal solution and a pore-guiding agent PDAs with HZSM-5 and then carrying out stirring to obtain slurry; conducting stirring to form a gel mixed solution; performing cooling, filtering, washing anddrying to obtain high-mesoporous-degree XZSM-5 molecular sieve; mixing the high-mesoporous-degree XZSM-5 molecular sieve with an NH4NO3 solution, carrying out ion exchange, and conducting drying and roasting for 2-3 hours to obtain a high-mesoporous-degree HZSM-5 molecular sieve seed crystal; and adding a dispersing agent and a silicon source, carrying out hydrothermal crystallization, and successively conducting washing, drying and roasting to obtain the high-mesoporous-degree HZSM-5@SiO2 composite molecular sieve. The high-mesoporous-degree HZSM-5@SiO2 composite molecular sieve prepared by the preparation method disclosed by the invention shows good catalytic performance and carbon deposition resistance in isomerization, alkylation and other reactions.

Description

technical field [0001] The invention belongs to the technical field of composite molecular sieve synthesis, in particular to a high mesopority HZSM-5@SiO 2 Preparation method of composite molecular sieve. Background technique [0002] HZSM-5 has a two-dimensional 10-membered ring channel, one of which is a 10-membered ring straight channel, and the other is a 10-membered ring channel with a Zigzag shape: the channel structure is [100] [010] Orthorhombic, Pnma, With its special pore structure, ZSM-5 molecular sieve not only provides a large number of access channels for reactants and products, but also provides good space restriction for shape-selective catalysis. [0003] HZSM-5 belongs to the orthorhombic molecular sieve with MFI structure (∣Na n (H 2 O) 16 ∣[Al n Si 96-n o 192 ]), the silicon-aluminum ratio can be from 10 until all-silicon Silicalite-1. The HZSM-5 molecular sieve structure contains strong acid sites (B acid) and weak acid sites (L acid), whi...

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Problems solved by technology

However, it is difficult to control the desilication rate by traditional alkali treatment using inorganic bases such as NaOH as alkaline reagents, which can easily lead to excessive desilication. Distributed mesoporous system; on the other hand, excessive desiliconization will cause serious damage to the skeleton structure, resulting in broken molecular sieve crystal structure, seriously affecting the catalytic effect (J.Mater.Chem.,2006,16(22):2121)

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