Preparation method and application of alveoli-like hierarchical porous MFI zeolite

Abstract

The invention relates to the field of molecular sieve catalysis, more specifically to a preparation method of an alveoli-like hierarchical porous MFI zeolite. The invention provides a preparation method and application of the alveoli-like hierarchical porous MFI zeolite with an appropriate acid amount, and the alveoli-like hierarchical porous MFI zeolite with an appropriate acid amount can be usedfor the catalytic reaction of a high silicon, weak acid and hierarchical porous molecular sieve, preferably for methanol to propylene reaction. The alveoli-like hierarchical porous MFI zeolite has atotal pore volume up to 1.00cm<3> / g or above, greatly improves the diffusion performance of the catalyst, and at the same time introduces an appropriate amount of acid site for MTP reaction. The alveoli-like hierarchical porous ZSM-5 composed of many small cavities obtained by the invention has a total pore volume up to 1.28cm<3> / g and a solid yield higher than 60%. In the methanol to propylene reaction, the catalytic life of the alveoli-like hierarchical porous MFI zeolite provided by the invention is more than twice that of high Si / Al ZSM-5 and ordinary hierarchical porous ZSM-5, and at thesame time the propylene selectivity is increased by 4%.

Description

technical field [0001] The invention relates to the field of molecular sieve catalysis, and more specifically relates to a preparation method of alveolar multi-level porous MFI zeolite. Background technique [0002] Zeolite is a microporous crystalline material with adjustable acidity, excellent channel shape selectivity and high hydrothermal stability, and is widely used in catalysis and separation. ZSM-5 zeolite is a catalytic material for methanol to propylene (MTP) reaction, but its microporous structure is prone to carbon deposition, which leads to its low stability in MTP reaction. How to further improve the catalyst stability and propylene selectivity is an important challenge for the MTP reaction, and the key lies in the design of the catalyst. [0003] Introducing mesoporous or macroporous structure into zeolite to prepare hierarchically porous zeolite can significantly improve the diffusion performance. In recent years, researchers have developed many methods for...

AI Technical Summary

Problems solved by technology

However, the Si / Al ratio of ZSM-5, which is suitable for alkali treatment to create mesopores, is about 25-50, and the amount of acid in the hierarchically porous ZSM-5 obtained by the treatment is relatively high, resulting in low propylene selectivity.

High Si / Al ZSM-5 has suitable amount of acid after alkali treatment, but the solid yield is less than 40%, while alkali treatment produces macroporous structure

There are certain challenges in the preparation of mesoporous ZSM-5 with high yield and suitable acid content by alkali treatment

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