Study On The Efficient Synthesis Of Zeolite MWW

Zeolite MWW has a wide range of potential applications in many fields such as aromatization,alkylation and catalytic cracking reactions due to its two independent channel systems.However,the synthesis of zeolite MWW is time-consuming(mostly longer than 7 days),and the organic template hexamethyleneimine(HMI)must be used.The synthetic efficiency is low and the cost is high,which limits its industrial application.Therefore,it is necessary to develop synthetic methods with higher efficiency to meet the increasing demand for zeolite MWW.This thesis proposes three efficient methods for synthesis of zeolite MWW:1)with the aid of the structure-directing gel,under static hydrothermal conditions,zeolite MWW can be synthesized without the gel-aging process.At the same time,the type of product can be selectively tuned to MCM-22 or MCM-49 by merely changing the synthetic temperature of the structure-directing gel;2)MCM-49 can be rapidly synthesized by steaming a concentrated gel and the synthetic time is shortened from 6 days to 36 hours,which is a 75%reduction;2)the organic template-free synthesis of MCM-49 is realized for the first time under static and dynamic hydrothermal conditions.The synthesized products can be used as seeds in a new round of synthesis process.Compared with commercial catalysts,zeolite MWW synthesized by the three methods exhibit superior catalytic performance for catalytic cracking of butene.