Dealumination kinetics of composite ZSM-5/mordenite zeolite during steam treatment: An in-situ DRIFTS study  

作　　者：Xiaoxiao Zhang Dangguo Cheng Fengqiu Chen Xiaoli Zhan 

机构地区：[1]Zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture Technology, College of Chemical and Biological Engineering, Zhejiang University

出　　处：《Chinese Journal of Chemical Engineering》2018年第3期545-550,共6页中国化学工程学报（英文版）

基　　金：Supported by the National Key Research and Development Program of China(2016YFA0202900);the National Natural Science Foundation of China(91434123,21622606);Zhejiang Provincial Natural Science Foundation of China(LR18B060001);the Fundamental Research Funds for the Central Universities

摘　　要：To get a better understanding of structural deactivation of ZSM-5/MOR during the catalytic cracking of n-heptane in the steam atmosphere, a comprehensive mechanism of hydrothermal dealumination was proposed through in-situ diffuse reflectance Fourier transform infrared spectroscopy(DRIFTS) in this work. The mechanism can be divided into two steps: firstly, the hydrolysis of four Al\\O bonds, and secondly, the self-healing of Si\\OH bonds accompanied with partial condensation of the extra-framework Al species. Accordingly, the kinetics of dealumination process has also been fully discussed. In the IR spectra, the range of 3450–3850 cm^(-1) could be deconvolved to distinguish the hydroxyl groups on the different position and calculate the consumption of each hydroxyl group during the reaction. Based on results from the in-situ DRIFTS, the kinetics of dealumination was hence developed and also in well agreement with the kinetics of deactivation of ZSM/MOR catalysts during the reaction in the presence of little coke deposits.To get a better understanding of structural deactivation of ZSM-5/MOR during the catalytic cracking of n-heptane in the steam atmosphere, a comprehensive mechanism of hydrothermal dealumination was proposed through in-situ diffuse reflectance Fourier transform infrared spectroscopy （DRIFTS） in this work. The mechanism can be divided into two steps：firstly, the hydrolysis of four Al-O bonds, and secondly, the self-healing of Si-OH bonds accompanied with partial condensation of the extra-framework Al species. Accordingly, the kinetics of dealumination process has also been fully discussed. In the IR spectra, the range of 3450-3850 cm^-1 could be deconvolved to distinguish the hydroxyl groups on the different position and calculate the consumption of each hydroxyl group during the reaction. Based on results from the in-situ DRIFTS, the kinetics of dealumination was hence developed and also in well agreement with the kinetics of deactivation of ZSM/MOR catalysts during the reaction in the presence of little coke deposits.

关 键 词：Zeolite Dealumination Kinetics Hydrothermal treatment 

分 类 号：TQ424.25[化学工程]