ZSM-5 is mainly prepared by the post-treatment method

In the preparation process, the zeolite molecular sieve of the hierarchically porous ZSM-5 is mainly prepared by the post-treatment method.

Specifically, the framework atoms of the molecular sieve can be selectively removed by methods such as acid or alkaline reagents and hydrothermal treatment. 

Thus, a certain amount of intragranular mesopores are introduced.

For the ZSM-5 zeolite molecular sieve, the desiliconization method is mainly used, 

which can selectively remove the framework silicon atoms of the ZSM-5 molecular sieve with an alkaline reagent to introduce the intracrystalline mesoporous structure. 

Compared with inorganic bases, desiliconization can be milder and more controllable. 

Abelló used tetrapropylammonium hydroxide (TPAOH) and tetrabutylammonium hydroxide (TBAOH) to treat ZSM-5 zeolite molecular sieves, 

which is found that quaternary ammonium salt cations can be adsorbed on the surface of the molecular sieve framework and can play a certain protective role, 

thereby reducing the OH- is removed, the dissolution rate of skeleton silicon is avoided, and the complementation of aluminum atoms is avoided, 

so as to realize the control of the degree of desiliconization modification (the treatment process comparison is shown in the figure).

Compared with the traditional ZSM-5 zeolite molecular sieve, the hierarchically porous ZSM-5 zeolite molecular sieve has better catalytic activity 

in the petrochemical field due to the introduction of a large number of mesopores, and improves the selectivity and stability. 

It is a relatively ideal catalyst for the alkylation of benzene and methanol in the chemical industry, and has good promotion and application prospects.