Modification method of all-silicon Beta molecular sieve containing three-membered ring

Abstract

The invention provides a modification method of an all-silicon Beta molecular sieve containing a three-membered ring and Lewis acid, and belongs to the field of petrochemical engineering. The method comprises the following steps: firstly, a Beta molecular sieve with the Si / Al ratio higher than 10 is used as raw powder, the Beta molecular sieve is subjected to continuous overtime addition through a nitric acid solution and then subjected to complete dealumination treatment, then deionized water is used for enabling the dealumination thickness of the Beta molecular sieve to be subjected to acid-base balance to obtain an all-silicon Beta molecular sieve, then the all-silicon Beta molecular sieve is dried and then fed into a muffle furnace to be roasted, and finally the all-silicon Beta molecular sieve containing the three-membered ring and Lewis acid is obtained. The method avoids the use of a fluorine-containing mineralizer in in-situ synthesis, and is green and environment-friendly; the obtained all-silicon Si-Beta molecular sieve contains a three-membered ring structure and effective Lewis acid sites, and can be used for isomerization reaction of olefin, the whole steps are simple, the preparation is quick, and the all-silicon Si-Beta molecular sieve is green and environment-friendly.

Description

technical field [0001] The invention relates to a method for modifying a three-membered ring-containing all-silicon Beta molecular sieve, which belongs to the field of petrochemical industry. Background technique [0002] Molecular sieves are widely used in the petrochemical industry due to their adjustable acid properties and unique pore structure. The acid properties of molecular sieves essentially determine the application and catalytic performance of molecular sieves. The acidic modulation of molecular sieves is difficult to control, and it is difficult to obtain molecular sieves with only Lewis acid. The Lewis acid in molecular sieves is mainly derived from non-framework aluminum species, and it is impossible to only exist in non-framework aluminum species in molecular sieves, generally there will be both framework aluminum and non-framework aluminum species, so in general molecular sieves there will be both acid and Lewis acid. Molecular sieves exist only Acids or...

AI Technical Summary

Problems solved by technology

[0004] All-silicon Beta molecular sieves are not easy to obtain through in-situ synthesis. In-situ synthesis generally requires hydrofluoric acid as a mineralizer. The synthesis process is not green and is not conducive to environmental protection.

CN111333082A and CN105800624A disclose the synthesis method of all-silicon Beta molecular sieves. They all used fluorine-containing mineralizers in the process of in-situ synthesis of all-silicon Beta molecular sieves. The synthesis conditions are relatively harsh, and the requirements of green environmental protection cannot be realized.

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