Synthesis method of integral hierarchical-pore ZSM-5 molecular sieve

Abstract

The invention provides a synthesis method of an integral hierarchical-pore ZSM-5 molecular sieve. The synthesis method comprises the following steps that 1, an aluminum source, sodium hydroxide, an organic template agent and deionized water are added to a beaker (1) to be mixed evenly, then a silicon source is gradually added to the beaker, intense stirring is performed to form homogeneous gel, and the homogeneous gel is poured into a stainless steel reaction kettle with a polytetrafluoroethylene liner and is crystallized at the temperature of 100-220 DEG C for 1-7 days; 2, the product obtained in the step 1 is repeatedly washed with the deionized water till a pH value is approximately neutral, and drying is performed at the temperature of 90-110 DEG C to obtain a ZSM-5 molecular sieve; 3, the ZSM-5 molecular sieve is roasted, and the organic template agent is removed to obtain the integral hierarchical-pore ZSM-5 molecular sieve. The steps of an existing integral hierarchical-pore catalyst preparation technology are simplified, expensive auxiliary materials such as structure guiding agents and special integral carriers are not needed, and the preparation cost is reduced.

Description

technical field [0001] The invention belongs to the technical field of molecular sieve preparation, and in particular relates to a method for synthesizing an integral multi-level porous ZSM-5 molecular sieve. Background technique [0002] U.S. Mobil Corporation reported the synthesis of ZSM-5 molecular sieve for the first time in 1972 (USP3702886), because of its ordered microporous structure, larger specific surface area, higher thermal and hydrothermal stability, skeleton acid center, It has become one of the most widely used catalysts in industry due to its excellent properties such as exchanged cations. However, the smaller micropore channels of the microporous ZSM-5 molecular sieve prevent larger molecules from entering the zeolite channels for adsorption and catalytic reactions, and limit the diffusion of macromolecules. In order to overcome the limitation of a single channel, researchers have considered solutions that combine the characteristics of channels at all le...

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Problems solved by technology

[0011] However, the synthesized nanosheet structure hierarchical porous ZSM-5 molecular sieve reported in the literature is a micron-sized powder, and it is necessary to add a binder or a surfactant to shape it or improve its strength.

The use of additives will block the pores of the molecular sieve, resulting in a reduction in the content of the active components of the catalyst, thereby reducing its catalytic performance

Although some researchers have also prepared monolithic catalysts, multi-step treatment or addition of special supports is required in the synthesis process, and there are still difficulties to be overcome such as complicated operating procedures and high synthesis costs.

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