Preparation method of hierarchical porous titanium silicon molecular sieve

Abstract

The invention discloses a method for preparing a multi-level porous titanium-silicon molecular sieve, which comprises the following steps: (1) After mixing the silicon source, the structure-directing agent, the titanium source and water uniformly in a certain proportion, directly adding a silylating agent or first After pre-crystallization, a silylating agent is added to obtain a reaction mixture containing a silylating agent; (2) the reaction mixture containing a silylating agent is crystallized under certain conditions in a pressure-resistant airtight container, and then recovered to obtain a crystallized product; (3) the recovered crystallized product is roasted and then treated with alkali to obtain an alkaline mixture; (4) the alkaline mixture is hydrothermally treated in a pressure-resistant airtight container, and the product is recovered. The hierarchically porous titanium-silicon molecular sieve obtained by the technical scheme has the advantages of high crystallinity, high macromolecular reactivity and selectivity, and adjustable pore 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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