ZSM-48/Silicalite-1 composite molecular sieve and preparation method thereof

Abstract

The invention discloses a ZSM-48 / Silicalite-1 composite molecular sieve and a preparation method thereof, the composite molecular sieve takes the ZSM-48 molecular sieve with low silica-alumina ratio as a shell phase, and takes Silicalite-1 as a core layer, total specific surface area of the composite molecular sieve is 330-400m<2> / g, the total pore volume is 0.22-0.28ml / g, average aperture is 2.5-3.5nm, by measuring gross weight of the composite molecular sieve, the shell layer content is 10-70%; wherein, mol ratio of silicon oxide of the ZSM-48 molecular sieve with low silica-alumina ratio to alumina is 25-50. The preparation method comprises the following steps: uniformly mixing the ZSM-48 molecular sieve with low silica-alumina ratio, sodium hydroxide, a template and water, adding silicon source to prepare a reaction mixture gel system, crystallizing the reaction mixture gel, separating the crystallization products, drying, and roasting to obtain the ZSM-48 / Silicalite-1 composite molecular sieve. The composite molecular sieve has good shape-selecting performance and anti-carbon deposition capability, and has latent industrial application value in alkylation and isomerization reactions.

Description

technical field [0001] The invention relates to a composite molecular sieve and a preparation method thereof, in particular to a ZSM-48 / Silicalite-1 composite molecular sieve and a preparation method thereof. Background technique [0002] In 1983, the patent US4397827 reported the synthesis of ZSM-48 molecular sieve for the first time. ZSM-48 molecular sieve is a molecular sieve with a ten-ring pore structure with a pore size of 0.53nm×0.56nm. It is an important isomerization catalytic material. In US7482300B2 and US7625478B2, it is described that ZSM-48 molecular sieve is used in the reaction process of C10 hydroisomerization. Under the condition that the conversion rate reaches 90%, the isomer product yield reaches more than 80%, showing good isomerization structural performance. [0003] At present, the research focus of ZSM-48 molecular sieve is still on its synthesis process. The synthesis process of this molecular sieve has the following characteristics: (1) The sili...

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Problems solved by technology

However, in the application process, it was found that ZSM-48 molecular sieve is very easy to deposit carbon, which is not conducive to the long-term operation of the catalyst, and the template agent hexamethylenediamine chloride used is also relatively expensive

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