Method for preparing Silicalite-1/ZSM-5 composite molecular sieve

Abstract

The invention discloses a method for preparing a Silicalite-1 / ZSM-5 composite molecular sieve. The method comprises the following steps of: crystallizing a mixture containing a silicon source, a ZSM-5 molecular sieve, tetrapropylammonium bromide, sodium hydroxide and water, and drying and roasting a crystallized product to obtain the core-shell structured Silicalite-1 / ZSM-5 composite molecular sieve taking the ZSM-5 molecular sieve as a core and Silicalite-1 molecular sieve as a shell. In the method, cheap template agent and silicon source are adopted and the production cost if greatly reduced; and the prepared Silicalite-1 / ZSM-5 composite molecular sieve has the advantages of high coverage rate, uniform coverage and the like.

Description

technical field [0001] The invention belongs to the field of molecular sieve synthesis, and in particular relates to a preparation method of a composite molecular sieve with ZSM-5 molecular sieve as the core and Silicalite-1 molecular sieve as the shell. Background technique [0002] At present, composite molecular sieves have attracted more and more researchers' attention. Various composite molecular sieves are constantly being synthesized. In 2006, Younes Bouizi (Chem Mater 2006, 18, 4959-4966) reported a composite molecular sieve Silicalite-1 / MFI with a core-shell structure. In the method, the ZSM-5 molecular sieve is wrapped with the Silicalite-1 molecular sieve to form a core-shell composite molecular sieve with the ZSM-5 as the core and the Silicalite-1 as the shell, and the coverage rate is 70% through one synthesis process. The specific synthesis process is as follows: first, nano-scale Silicalite-1 seeds are deposited on the surface of ZSM-5 molecular sieves throu...

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Problems solved by technology

[0004] Said method synthesizes Silicalite-1 / H-ZSM-5 composite molecular sieve process owing to adopted TEOS-TPAOH-EtOH-H 2 O synthesis system adopts two-step synthesis, the steps are more complicated, and the yield of solid product is low, and the expensive template agent TPAOH and silicon source TEOS are used in the synthesis of Silicalite-1, which increases the production cost and requires many times. Synthesis, one-time synthesis coverage is low

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