Titanium silicalite molecular sieve, preparation method thereof and method for producing ketoxime through ammoximation reaction of macromolecular ketones

Abstract

The invention relates to a titanium silicalite molecular sieve and a preparation method thereof, and a method for producing ketoxime through an ammoximation reaction of macromolecular ketones, the titanium silicalite molecular sieve is composed of an oxygen element, a silicon element and a titanium element, and the molar ratio of TiO2 to SiO2 of the titanium silicalite molecular sieve is 1: (20-100) in terms of oxide and in terms of molar weight; the ratio of the surface titanium-silicon ratio to the bulk phase titanium-silicon ratio of the titanium-silicon molecular sieve is 1.5-3.6, and the titanium-silicon ratio refers to the molar ratio of TiO2 to SiO2; and when the titanium silicalite molecular sieve is subjected to an ultraviolet-visible spectrum test, the ratio of the area of a spectrum peak with the displacement of 210 nm to the sum of the areas of spectrum peaks with the displacement of 210 nm, 270 nm and 330 nm is recorded as a / b, and a / b is 55% or above. The titanium silicalite molecular sieve is rich in titanium on the surface, high in framework titanium content and high in catalytic activity, and the raw material conversion rate and the target product selectivity can be improved when the titanium silicalite molecular sieve is applied to a ketoxime production process through a macromolecular ketone ammoximation reaction.

Description

technical field [0001] The disclosure relates to a titanium-silicon molecular sieve and a preparation method thereof, and a method for producing ketoxime by ammoximation reaction of macromolecular ketones. Background technique [0002] Titanium-silicon molecular sieve is a new type of heteroatom molecular sieve developed in the early 1980s, which refers to a type of heteroatom molecular sieve containing titanium skeleton. The currently synthesized microporous titanium silicate molecular sieves include TS-1 (MFI structure), TS-2 (MEL structure), Ti-Beta (BEA structure), Ti-ZSM-12 (MTW structure) and Ti-MCM-22 ( MWW structure), etc. Mesoporous titanium-silicon molecular sieves include Ti-MCM-41 and Ti-SBA-15, etc. The development and application of titanium-silicon molecular sieves has successfully expanded zeolite molecular sieves from the field of acid catalysis to the field of catalytic oxidation, which is a milestone. Among them, the Italian Enichem company first announc...

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Problems solved by technology

However, in this process, there are many factors that affect the insertion of titanium into the framework, the conditions of hydrolysis, crystallization nucleation, and crystal growth are not easy to control, and there is a certain amount of titanium that cannot be effectively inserted into the molecular sieve framework and stays in the channel in the form of non-skeleton titanium. The production of non-skeletal titanium not only reduces the number of catalytic active centers, but also non-skeletal titanium-silicon species will promote the ineffective decomposition of hydrogen peroxide, resulting in waste of raw materials. Therefore, the TS-1 molecular sieve synthesized by this method has low catalytic activity, poor stability, and difficult to reproduce.

[0004] In the preparation method of titanium-silicon molecular sieve TS-1 disclosed by Thangaraj et al. (Zeolites, 1992, Vol.12 pages 943-950), in order to effectively improve the insertion of titanium into the molecular sieve framework, organic silicon grease is firstly hydrolyzed, and then organic silicon grease is slowly added dropwise. The strategy of hydrolyzing titanium ester matches the hydrolysis speed of organosilicon and titanium, and introduces isopropanol during the hydrolysis of titanium. However, the titanium-silicon molecular sieve TS-1 obtained by this method is limited in increasing the titanium content of the skeleton, and there are still some problems. A large amount of non-skeletal titanium such as anatase, the catalytic activity is not high

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