A kind of preparation method of rare earth modified multi-stage porous titanium silicon molecular sieve

Abstract

The invention relates to a preparation method of a rare-earth modified multistage porous titanium silicalite molecular sieve. The preparation method comprises the following steps: (1) adding a templating agent and water into a silicon source under continuous stirring, and completely hydrolyzing the silicon source to obtain a colorless and transparent solution A; (2) adding a mixed solution B of a titanium source, a rare-earth compound and isopropanol into the solution A to obtain a solution C, and after removing isopropanol in the solution C at a certain temperature, further drying the solution C at a certain temperature to obtain dried gel; and (3) after grinding the dried gel, transferring the dried gel into a tetrafluoroethylene cup, then, placing the tetrafluoroethylene cup into a hydrothermal reaction kettle, carrying out reaction under the condition of steam-assisted crystallization to obtain a product, and cleaning, drying and roasting the product to obtain the rare-earth modified multistage porous titanium silicalite molecular sieve. Compared with the prior art, the molecular sieve obtained by using the method disclosed by the invention has abundant mesopores and extremely high outer specific surface area and is capable of effectively improving the catalytic oxidation performance of the titanium silicalite molecular sieve to sulfur compounds with relatively large molecular diameters.

Description

technical field [0001] The invention belongs to the technical field of preparation and application of zeolite molecular sieve catalysts, and in particular relates to a preparation method of a rare earth-modified multi-stage porous titanium-silicon molecular sieve. Background technique [0002] Since its synthesis in 1983 (USP 4410501), titanium-silicon molecular sieve TS-1 has been widely used in the oxidation of small organic molecules such as phenols, olefins, ammonia, and alkanes due to its excellent catalytic oxidation performance. However, since the active center of TS-1 mainly exists in its micropore channel (0.54*0.56nm), it cannot effectively catalyze the oxidation of molecules whose molecular diameter is larger than that of the micropore. These greatly limit the catalytic performance and application range of TS-1. [0003] At present, a lot of research work aims to introduce mesoporous channels (>2nm) into TS-1 to obtain TS-1 with hierarchical channels to solve ...

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Problems solved by technology

However, the method used in this patent is the traditional hydrothermal method, which has the disadvantages of large waste liquid, slow crystallization speed, and high energy consumption. Moreover, the prepared molecular sieve has a small external specific surface area and relatively low mesopore volume.

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