Large-particle titanium silicalite molecular sieve with excellent diffusion performance and preparation method thereof

Abstract

The invention provides a large-particle titanium silicalite molecular sieve TS-1 with excellent diffusion performance. The morphology of the molecular sieve is a cuboid, and the longest side size is 4-20 [mu]m; and a large number of spherical holes with the diameter of 70-100 nm are formed inside. The invention also provides a preparation method of the molecular sieve. Carbonate is used as a hardtemplate of a hole structure, tetrapropylammonium bromide is used as a microporous template agent, and the molecular sieve is prepared by an acid treatment method. The hole structure of the molecularsieve prepared by the method is more beneficial to diffusion of macromolecules, so that the limitation of intrinsic micropore channels of the TS-1 molecular sieve on catalytic reaction is overcome, and non-framework titanium can be removed and the removal of the framework titanium is inhibited through acid treatment. Therefore, compared with the conventional microporous TS-1, the titanium silicalite molecular sieve provided by the invention has higher catalytic activity on a larger molecular selective oxidation reaction and has better stability on a smaller molecular selective oxidation reaction.

Description

technical field [0001] The invention relates to a preparation method of a large particle titanium-silicon molecular sieve TS-1 with a regular cavity structure inside. Background technique [0002] Zeolite molecular sieve is a crystalline porous material with uniform pores, high specific surface area, flexible framework and controllable synthesis, making it widely used in catalysis, purification, adsorption, separation and other industrial fields. Titanium-silicon molecular sieve TS-1 is a heteroatom molecular sieve with catalytic oxidation activity by introducing transition metal titanium atoms into the molecular sieve framework with MFI topology. Since the synthesis of titanium-silicon molecular sieve TS-1 was first reported in US Patent US4410501 in 1983, titanium-silicon molecular sieves were used as catalysts and H 2 o 2 It is a mild reaction system formed by an oxidant. It exhibits high activity and high selectivity in selective oxidation reactions of organic substanc...

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Problems solved by technology

The post-treatment method is to first synthesize the TS-1 precursor, and then treat it with an alkaline solution to form a mesoporous or macroporous structure (Appl.Catal., A 2013,453,272), but in the alkali treatment process, TS-1 Part of the active center of the framework titanium will be converted into non-framework titanium or anatase TiO 2 , which is unfavorable for the selective oxidation reaction

And, used organic base (as tetrapropyl ammonium hydroxide) price is also more expensive, very big influence to the preparation cost of catalyst

[0005] The one-step method is to add mesoporous and microporous templates to the synthesis system at the same time to synthesize a mesoporous composite titanium-silicon molecular sieve (Ind. Eng. Chem. Res. 2017, 57, 512). Phase separation, it is difficult to achieve the purpose of mesoporous composite

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