Stepped-type crystallization preparation method of titanium-containing molecular sieve

Abstract

The invention relates to a synthesis method of a titanium-containing molecular sieve, and particularly relates to a method for preparing a titanium-containing molecular sieve by adopting a stepped crystallization also called as a lattice vacancy filling method. The invention provides a method for fast preparing a TS-1 molecular sieve, which is simple and feasible and relatively low in cost. According to the technical scheme, the stepped crystallization preparation method of the titanium-containing molecular sieve comprises the following steps: 1, sufficiently hydrolyzing a tetrapropylammonium hydroxide solution added with an inorganic silicon source to prepare gel; 2, transferring the gel to a sealed reaction kettle, carrying out pre-crystallization to prepare a pure silicon molecular sieve guiding agent, then slowly dropwise adding a titanium source to the pure silicon molecular sieve guiding agent, and continuously pre-crystallizing for 1-6 hours to obtain a mixture to be crystallized; 3, crystallizing the mixture to be crystallized, controlling the temperature to rise to 160-200 DEG C, and carrying out hydrothermal crystallization for 6-48 hours to obtain the titanium-containing molecular sieve.

Description

technical field [0001] The invention relates to a method for synthesizing titanium-containing molecular sieves, in particular to a method for preparing titanium-containing molecular sieves by adopting stepwise crystallization or filling vacant positions in crystal lattices. Background technique [0002] Titanium-containing molecular sieves are heteroatom molecular sieves developed in the early 1980s. At present, TS-1 with MFI structure, TS-2 with MFL structure, and TS-48 with larger pore structure have been synthesized. This type of molecular sieve framework contains transition metal titanium atoms with variable valence characteristics, which enables it to form redox catalysis and has shape-selective functions, so it has excellent directional catalytic oxidation performance and can be used as a new generation of green chemical catalysts for selective oxidation. For example, titanium-silicon molecular sieves have excellent catalytic activity and directional oxidation performa...

AI Technical Summary

Problems solved by technology

This method effectively solves the problem of titanium polymerization in the synthesis process, but the introduction of acid will neutralize a part of TPAOH in the synthesis, which will increase the amount of TPAOH in the system, resulting in high cost

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