Method for direct hydrothermal synthesis of chabasite with intermediate silica-alumina ratio

Abstract

The invention provides a method for direct hydrothermal synthesis of chabasite with an intermediate silica-alumina ratio. The method is characterized by comprising the steps that in a reaction for synthesizing the chabasite under the hydrothermal condition, no organic template is added, no chabasite seed crystal is added, alkalescent inorganic salt is added, and an aluminosilicate zeolite molecular sieve with a chabasite structure is obtained; reacting matter for preparing hydrogel is prepared from, by molar ratio, 1-20 parts of Na2O, 2-30 parts of K2O, 0.05-8.0 parts of alkalescent inorganic salt, 1 part of Al2O3, 8-80 parts of SiO2 and 150-800 parts of H2O. According to the method, the zeolite molecular sieve with the chabasite structure can be synthesized stably without using template or fluorochemicals or seed crystals.

Description

technical field

[0001] The invention belongs to the field of preparation of zeolite molecular sieves, in particular to a method for synthesizing zeolite molecular sieves with a chabazite structure. Background technique

[0002] Chabazite has a CHA crystal structure and belongs to the trigonal crystal system. The unit cell parameters are: a=13.7 angstroms, c=14.8 angstroms. In the structure, aluminum-oxygen tetrahedrons and silicon-oxygen tetrahedrons are strictly alternately connected, and the skeleton is staggered by double six-membered rings. A cage structure is formed, and the pore diameter of the eight-membered ring channel in the a and b directions is 3.8 angstroms×3.8 angstroms. Chabazite with a low silicon-aluminum ratio can be used as a gas adsorbent, and has adsorption properties for nitrogen, oxygen, and argon. The SSZ-13 and synthetic chabazite with medium and high silicon-aluminum ratio can be used as the raw material of the catalyst, and can be used as the acti...

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