ZSM-5 molecular sieve containing cavity structure as well as preparation method and application of ZSM-5 molecular sieve

The ZSM-5 molecular sieve with cavity structures was directly synthesized by two-step crystallization method, which solved the problem of micropore structure failure after alkali treatment in the prior art, and achieved higher small-molecular hydrocarbon conversion and propylene yield.

CN119706867AActive Publication Date: 2025-03-28CHINA PETROLEUM & CHEMICAL CORP +1
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Patent Information

Application Number
CN202311253599.5
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2023-09-26
Publication Date
2025-03-28
Estimated Expiration
2043-09-26

AI Technical Summary

Technical Problem

After alkali treatment of the existing ZSM-5 molecular sieve with cavity structure, some of the microporous structures are destroyed, resulting in a decrease in the crystallinity of the molecular sieve in the product, which is not conducive to the conversion of small-molecular hydrocarbons.

Method used

The ZSM-5 molecular sieve with a cavity structure is directly synthesized by a two-step crystallization method. The first step is to add an aluminum source and a template agent to the alkali source solution, stir and add a silicon source to conduct hydrothermal dynamic crystallization; the second step is to add a mixed inorganic alkali source containing at least two inorganic alkalis, and high-temperature crystallization is performed to obtain a ZSM-5 molecular sieve with a cavity structure, without subsequent alkali treatment.

Benefits of technology

Through the direct synthesis method, the micropore structure integrity of ZSM-5 molecular sieve was maintained, and the conversion rate and propylene yield of small molecule normostatic hydrocarbons in catalytic cracking were improved.

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Abstract

The invention relates to a ZSM-5 molecular sieve containing a cavity structure as well as a preparation method and application of the ZSM-5 molecular sieve. The molecular sieve is a ZSM-5 molecular sieve containing a cavity structure and synthesized by adopting a two-step crystallization method, alkali treatment is not needed, the size of a cavity is 0.5-5 microns, the specific surface area of mesopores accounts for 3-10% of the total specific surface area, and the volume of the mesopores accounts for 15-30% of the total pore volume; the two-step crystallization method comprises a first crystallization step A and a second crystallization step B. In the step A, a silicon source, an aluminum source, an organic template agent and a certain amount of water are uniformly mixed according to a certain ratio at a certain temperature to obtain a first crystallization product, and in the step B, a mixed inorganic base source containing at least two inorganic bases is added into the first crystallization product to obtain a second crystallization product. The second crystallization product is the ZSM-5 molecular sieve containing the cavity structure.
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