A kind of preparation method of preformed L-type molecular sieve

Abstract

The invention relates to a method for preparing a preformed L-type molecular sieve, comprising: (1), mixing kaolin, forming aids and water, forming, drying and roasting to obtain a preform; (2), preparing the obtained preform The body is modified, washed and dried to obtain a modified preform; (3), the modified preform, inorganic alkali, silicon source and water are mixed, and the molar ratio of each material in the resulting mixture is (1-4 ) M 2 O: Al 2 o 3 : (6‑12) SiO 2 : (100‑250)H 2 O, the mixture was subjected to hydrothermal crystallization, and the crystallized product was washed and dried. The preformed L-type molecular sieve prepared by the method of the present invention can be directly used as a carrier without remolding, avoiding the problem of difficult filtration of nano-sized molecular sieves, and is especially suitable for the industrial production of nano-scale L-type molecular sieves, and the L-type molecular sieves have high crystallinity .

Description

technical field [0001] The invention relates to a preparation method of L molecular sieves, in particular to a preparation method of preformed L-type molecular sieves. Background technique [0002] Nano-molecular sieves refer to ultra-fine molecular sieves with crystal grains less than 100nm. The filtration and collection efficiency of granular molecular sieves is extremely low, and its industrial application is limited. [0003] The current conventional method for industrially preparing L-type molecular sieves is the hydrothermal crystallization method. This method is usually in an alkaline aqueous solution, according to a certain molar ratio composition and feeding sequence, mix the silicon source and the aluminum source evenly and put them into a stainless steel reactor, and crystallize at 100-180°C for 24-80h or even longer . Usually white carbon black, sodium silicate, potassium silicate or silica sol is used as the silicon source; aluminum hydroxide, potassium alumi...

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Problems solved by technology

[0006] In the above method, the synthesized molecular sieve is in the form of extremely fine powder. In order to meet the requirements of industrial applications, it is necessary to use forming aids to make powdery molecular sieves into molecular sieve carriers of different shapes, which can meet the mechanical strength of industrial applications, and then further manufacture The addition of forming aids will dilute the molecular sieve powder and reduce its effective specific surface area. At the same time, the forming aids will also block the pores of molecular sieves and affect the diffusion of reactive molecules.

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