Cleaner process for synthesis of zeolite MCM-22 by vapor-phase transport method

摘要

A cleaner process for synthesis of zeolite MCM-22 by vapor-phase transport method was studied in this paper. Firstly, zeolite MCM-22 was synthesized at different hexamethyleneimine (HMI) dosages by vapor-phase transport (VPT) method. It was concluded that the aluminosilicate gel was not crystallized completely and the product crystallinity was low when the HMI/gel mass ratio was <0.3. Then, the as-synthesized product and the surplus liquid, which were obtained at mass ratio 0.3 HMI : 1.0 gel, were characterized by TG-DTA and FTIR, respectively. It was found that a part of HMI did not play the role of structure-directing and remained in the surplus liquid after synthesis of zeolite MCM-22. The surplus liquid chemical properties, which have not change after synthesis of zeolite MCM-22 by VPT method, still contained only HMI and H_2O. Re-adding of HMI and deionized water, the surplus liquid was reused to synthesize zeolite MCM-22 by VPT method. Based on the experimental results of surplus liquid reuse, it was known that the surplus liquid can be reused via re-adding of HMI and deionized water. It could make the VPT method become a cleaner process.