Inorganic synthesis method for regulating morphology of ZSM-5 molecular sieve

Abstract

The invention provides an inorganic synthesis method for regulating the morphology of a ZSM-5 molecular sieve. The method at least comprises the following steps: (1) adding a silicon source, an alkali source and an aluminum source into pure water respectively, and stirring uniformly to obtain silica-alumina gel; (2) adding a molecular sieve morphology regulation inorganic additive and a zeolite seed crystal into the silica-alumina gel, and stirring uniformly to obtain a gel mixture; and (3) transferring the gel mixture into a sealed reaction kettle for crystallization, and then separating and drying the crystallized product to obtain a ZSM-5 molecular sieve, wherein the morphology of the ZSM-5 molecular sieve is suitable to be controlled by regulating the addition amount of the molecular sieve morphology regulation inorganic additive. Through the method provided by the invention, a low-silicon ZSM-5 molecular sieve with a regulatable morphology and a silica-alumina ratio controllable in a certain range can be obtained, and the low-silicon ZSM-5 molecular sieve has relatively high crystallinity and purity and good aromatization reaction performance; and moreover, a roasting step is saved in the production process, and environmental pollution is reduced.

Description

technical field [0001] The invention belongs to the field of inorganic chemistry and relates to the technical field of molecular sieve preparation, in particular to an inorganic synthesis method for regulating the morphology of ZSM-5 molecular sieve. Background technique [0002] The ZSM-5 molecular sieve with MFI structure and its heteroatom-substituted molecular sieves are widely used in aromatization and other reactions due to their strong acidity. At present, the development of aromatization catalysts mainly focuses on the 2 / Al 2 o 3 Relative, strongly acidic, small-grain ZSM-5 molecular sieves are synthesized and modified, among which, the morphology regulation of ZSM-5 molecular sieves also has an important influence on the catalyst activity and selectivity. For example, the straight channels parallel to the b-axis in ZSM-5 molecular sieve crystals are more conducive to the transport and diffusion of molecules in it, while the zigzag-type channels parallel to the a...

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Problems solved by technology

[0003] In view of the shortcomings of the prior art described above, the object of the present invention is to provide an inorganic synthesis method for regulating the morphology of ZSM-5 molecular sieves, which is used to solve the problem of the need to add an organic template as a directing agent or add organic matter to solve the problem in the prior art. Regulating the morphology of molecular sieves will not only increase the cost but also cause environmental pollution. At the same time, it will cause the problem of irreversible agglomeration of nano ZSM-5 molecular sieves, and the SiO 2 / Al 2 o 3 relatively high problem

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