Preparation method of preformed L-shaped molecular sieve

Abstract

The invention relates to a preparation method of a preformed L-shaped molecular sieve. The method comprises the following steps: (1) mixing kaolin, a forming assistant and water, forming, drying, androasting to obtain a preformed body; (2) performing modification treatment on the preformed body, washing, and drying to obtain a modified preformed body; and (3) mixing the modified preformed body, an inorganic alkali, a silicon source and water according to a molar ratio of (1-4)M2O:Al2O3:(6-12)SiO2:(100-250)H2O, carrying out hydrothermal crystallization on the mixture, washing the crystallizedproduct, and drying. According to the invention, the preformed L-shaped molecular sieve prepared by the method disclosed by the invention can be directly used as a carrier without forming again, so that the problem of difficult filtration of a nano-crystalline grain size molecular sieve is avoided; and the method is particularly suitable for industrial production of a nano-scale L-shaped molecularsieve, and is high in crystallinity degree of the L-shaped molecular sieve.

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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