A kind of titanium silicon molecular sieve and its synthesis method and application and a kind of method of phenol hydroxylation

Abstract

The invention relates to the field of molecular sieves and in particular to a titanium silicalite molecular sieve and a synthetic method and an application thereof. The method comprises the following steps of: (1) hydrolyzing an organic silicon source, a titanium source, a noble metal source and an alkaline template to obtain a mixture A, and performing first crystallization on the mixture A; and (2) mixing the firstly crystallized material with the titanium silicalite molecular sieve original powder to obtain a mixture B, and performing secondary crystallization on the mixture B, wherein the sold content of the mixture B is 30-80wt% by means of the dosage of the titanium silicalite molecular sieve original powder. The invention also provides a method of hydroxylation of phenol. The relative crystallinity of the titanium silicalite molecular sieve prepared by the method is relatively high, the surface silicon-titanium ratio is high, the particle size is relatively uniform, the feeding amount of Ti is high, and the pore volume and outer specific surface area are large.

Description

technical field [0001] The invention relates to a method for synthesizing a titanium-silicon molecular sieve, a titanium-silicon molecular sieve synthesized by the method, an application of the titanium-silicon molecular sieve in an oxidation reaction, and a method for phenol hydroxylation. Background technique [0002] Titanium-silicon molecular sieve TS-1 is a new type of titanium-silicon molecular sieve with excellent catalytic selective oxidation performance formed by introducing transition metal element titanium into the molecular sieve framework with ZSM-5 structure. TS-1 not only has the catalytic oxidation effect of titanium, but also has the shape-selective effect and excellent stability of ZSM-5 molecular sieve. Since TS-1 molecular sieve can use non-polluting low-concentration hydrogen peroxide as an oxidant in the oxidation reaction of organic matter, it avoids the problems of complex oxidation process and environmental pollution, and has incomparable energy savi...

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Problems solved by technology

In the process of gelation, the hydrolysis conditions of the mixed solution of silicon ester and titanium ester are very strictly controlled, because the hydrolysis speed of the two does not match, the latter is higher than the former, and the addition of organic base at a slightly faster speed will produce irreversible titanium. These titanium polymers are difficult to enter the framework during the crystallization process, and most of them are mixed in the molecular sieve in the form of non-skeleton titanium. This part of titanium may not only block the pores, but also catalyze the decomposition of hydrogen peroxide, wasting raw materials

[0004] Since then, researchers have made many attempts and improvements to the synthesis methods of titanium-silicon molecular sieves, but the existing production methods still have problems such as low solid content, long production cycle, uneven distribution of titanium, and poor preparation repeatability; especially titanium-silicon When molecular sieves are used in catalytic oxidation reactions, there are generally problems such as large grains of titanium-silicon molecular sieves, low activity, and small grains, which are difficult to filter and separate.

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