Synthesis method of MCM-22 family molecular sieve

Abstract

The invention discloses a synthesis method of an MCM-22 family molecular sieve. The method is characterized by comprising the steps of: adding a dilute acid water solution into a hexamethyleneimine template agent; adding a silicon source, an aluminium source, an alkali source, water and an acidified template agent (R) in proportion so as to prepare gel; conducting hydrothermal crystallization, opening a valve under constant temperature, carrying out pressure reduced evaporation to the molecular sieve slurry, recovering the liquid mixture and the template agent; adding a cold dilute acid water solution into the residual slurry, and opening the kettle when the temperature of the residual slurry drops below 50DEG C, performing filtration so as to obtain a solid product, thus obtaining a MCM-22 family molecular sieve finally. With the method provided in the invention, the template agent no longer volatizes, and damage to the human body can be avoided. Meanwhile, stability of the synthesis formula and quality of the molecular sieve is guaranteed. When the template agent is acidified into a salt, the dispersibility is greatly increased, and the obtained MCM-22 family molecular sieve has a uniform crystal phase as well as a high degree of crystallization. After crystallization, the synthesis slurry is subjected pressure reduced evaporation and the template agent is recovered. After acidification, the recovered template agent can be used for MCM-22 family molecular sieve synthesis again.

Description

technical field [0001] The invention belongs to the field of zeolite molecular sieve catalysts, and relates to a synthesis method of MCM-22 family molecular sieves. Background technique [0002] MCM-22 molecular sieve is a layered molecular sieve with MWW topology, which was first synthesized by Mobil in 1990 under the hexamethyleneimine template system. It has two independent pore systems: interlayer ten-membered ring (0.40 ×0.59nm) connected channel system, ten-membered ring two-dimensional sinusoidal channel system in the layer and twelve-membered ring holes (0.71×0.71×1.82nm) on the outer surface of the crystal. Later, molecular sieves such as MCM-49, MCM-56, MCM-36, ITQ-1 and ITQ-2 were synthesized under the hexamethyleneimine template system, and they were also found to be layers with MWW structure. shape molecular sieve. Therefore, these molecular sieves are collectively referred to as MCM-22 molecular sieves. MCM-22 molecular sieves have broad application prospect...

AI Technical Summary

Problems solved by technology

Due to its high toxicity, strong corrosiveness and high volatility, it is easy to cause great harm to the human body and affect the stability of synthetic formula and product quality

In addition, due to the poor dispersion of hexamethyleneimine in the initial gel, the crystal phase of the synthesized product is not uniform

Although some scholars try to synthesize MCM-22 molecular sieves by using binary templates, they cannot completely replace hexamethyleneimine templates.