Modification method for titanium silicalite molecular sieves

Abstract

The invention relates to a modification method for titanium silicalite molecular sieves, which aims to further improve the catalytic activity and stability of the titanium silicalite molecular sieves. The method is used for processing a titanium silicalite molecular sieve subjected to strip extrusion molding, so that a carrier introduced by strip extrusion can be crystallized and formed into a new molecular sieve skeleton with catalytic activity, and no negative impact is produced on the strength of the strip titanium silicalite molecular sieve. Compared with modified molecular sieves prepared in the prior art, the modified titanium silicalite molecular sieve prepared by using the modification method has higher catalytic activity and a longer service life to selective catalytic oxidation reaction such as alkene epoxidation, phenol hydroxylation, and ketone ammoxidation.

Description

technical field [0001] The invention relates to a method for modifying titanium-silicon molecular sieves. Background technique [0002] Since the synthesis of titanium-silicon molecular sieve TS-1 was first reported in U.S. Patent 4410501 in 1983, its oxidation system composed of hydrogen peroxide has shown excellent catalytic activity and Selectivity, and the by-product is water, which is an environmentally friendly process, so it has attracted widespread attention. Subsequently, various Ti-containing heteroatom molecular sieves, such as TS-2, Ti-β, Ti-MCM-22, Ti-SBA-15, and Ti-TUD-1, were synthesized and used to catalyze selective oxidation reactions. . [0003] Titanium-silicon molecular sieves with different pore structures have certain pore shape selectivity for catalyzing reactants with different molecular sizes. Microporous molecular sieves such as TS-1 and TS-2 have a small pore size and have high reactivity for small molecules (such as propylene epoxidation), but...

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Problems solved by technology

This molding method has the advantage of high content of active components, but it also has the problem that the heat of reaction is not easily diffused from the inside of the catalyst particle to the outside, and the addition of a carrier or binder will block the pores of the molecular sieve, greatly improving its catalytic activity. decline

Our research group found (Ind.Eng.Chem.Res.2012,51,10586), H 2 o 2 Washing can cause the binder to fall off, thereby exposing a certain amount of pores and restoring its catalytic activity. However, the loss of the binder may have a negative impact on the strength of the strip catalyst

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