Method for preparing multistage-hole ZSM-5 molecular sieve

Abstract

The invention discloses a method for preparing a multistage-hole ZSM-5 molecular sieve, and belongs to the technical field of synthesis of molecular sieves. The invention provides the preparation method of the multistage-hole ZSM-5 molecular sieve which is low in cost and low in pollution, can change a silicon aluminum ratio (30-100) to the molecular sieve in a wide range, and has a large mesoporous volume. The method comprises the following steps of I, preparing crystal seeds for the synthesis of the multistage-hole ZSM-5 molecular sieve; II, preparing mixed gel, and performing stirring at room temperature; III, adding the crystal seeds prepared in the step I into the gel obtained in the step II, performing low-temperature crystallization for a short time, and adding a little organic silicon; and IV, continuing crystallization, performing cooling, performing centrifugal filtration, performing washing, performing drying, and performing roasting so as to obtain the multistage-hole ZSM-5 molecular sieve. According to the method provided by the invention, a few organic amine template agents are used only in the crystal seed synthesizing process, an s small, so that d besides, the addition amount of the added organic silicon as a mesoporous hole forming agent i compared with a method for synthesizing other multistage-hole ZSM-5 molecular sieve, the method disclosed by the invention has the advantages that the dosage of the template agents is small, products have a large mesoporous volume, and the problems that the production cost of the molecular sieve is high and environment is polluted caused by the condition that the organic template agent is high in price and large in toxicity can be solved.

Description

technical field [0001] The invention belongs to the technical field of molecular sieve synthesis; in particular, it relates to a method for preparing a multi-stage porous ZSM-5 molecular sieve. Background technique [0002] Zeolite molecular sieve materials with multi-level channels not only have the strong acidity and hydrothermal stability of zeolite molecular sieves, but also the molecular diffusion coefficient in mesopores (macropores) is higher than that in traditional microporous molecular sieve channels. order of magnitude, making it expected to play an important role in catalytic reactions involving macromolecules. The ZSM-5 zeolite molecular sieve with MFI topology and three-dimensional intersecting channel system has uniform pore size (average pore size 0.54×0.56nm); abundant access channels ("Z" shaped channels and intersecting elliptical straight channels The composition of the pore structure), high thermal stability and hydrothermal stability, moderate acidity ...

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Problems solved by technology

[0003] The object of the present invention is to provide a kind of method for preparing hierarchical porous ZSM-5 molecular sieve, compared with other method for synthesizing hierarchical porous ZSM-5 molecular sieve molecular sieve, has larger mesopore volume, and template agent consumption reduces greatly, solves the problem The high price and high toxicity of organic templates lead to high production costs of molecular sieves and environmental pollution.

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