A kind of method for preparing hierarchical porous titanium silicon molecular sieve

Abstract

The invention discloses a preparation method of a hierarchical porous titanium silicon molecular sieve, wherein the method comprises the following steps: (1) mixing a silicon source, a structure directing agent, a titanium source and water evenly according to a certain ratio, and directly adding a silanization reagent, or firstly pre-crystallizing and then adding a silanization reagent, to obtain a reaction mixture containing the silanization reagent; (2) crystallizing the reaction mixture containing the silanization reagent in a pressureproof closed container under certain conditions, and recycling to obtain a crystallized product; (3) carrying out roasting treatment of the crystallized product, and then carrying out alkali treatment to obtain an alkaline mixture; and (4) carrying out hydrothermal treatment of the alkaline mixture in the pressureproof closed container, and recycling to obtain the product. The hierarchical porous titanium silicon molecular sieve obtained by the method has the advantages of high crystallinity, high macromolecule reaction activity and selectivity, and adjustable pore passage structure.

Description

technical field [0001] The invention relates to a method for synthesizing a titanium-silicon molecular sieve, in particular to a method for preparing a multi-level porous titanium-silicon molecular sieve. Background technique [0002] Titanium-silicon molecular sieves refer to a class of heteroatom molecular sieves containing four-coordinated titanium framework. Since Enichem first announced the titanium-silicon molecular sieve TS-1 with MFI structure in 1983, people have successively developed a series of titanium-silicon molecular sieves with different skeleton structures. Such as TS-2 of MEL structure, Ti-beta of BEA structure, Ti-ZSM-12 of MTW structure and Ti-MCM-22 of MWW structure, etc. [0003] TS-1 has a two-dimensional ten-membered ring channel system, the [100] direction is a straight channel with a diameter of 0.51×0.55nm, and the [010] direction is a sinusoidal channel with a diameter of 0.53×0.56nm. Due to the introduction of Ti atoms and its special pore str...

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Problems solved by technology

[0009] In summary, either inorganic or organic base treatment alone can construct titanium-silicon molecular sieves with a certain multi-level pore size, but inorganic base treatment has problems such as large loss of molecular sieve quality and crystallinity, difficulty in the treatment of inorganic salts and inorganic bases, etc. ; Although organic base treatment can introduce larger-sized mesopores into molecular sieves, but they are coated inside molecular sieves, and the macromolecular reaction performance of molecular sieves has not been effectively improved.

However, the silanization treatment method has problems such as low crystallinity of the crystallized product and silanization reagents affecting Ti entering the molecular sieve framework.

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