Modifying Crystal Morphology And Framework Composition Of Composition Of Zeolite L (LTL) – A Co-Solvent Approach
thesisposted on 22.05.2021, 08:56 by Adriana Gaona-Gomez
The first part of this study investigates synthesis protocols to tune the size and the morphology of zeolite L (LTL) crystals using three different glycols. The outcomes clearly demonstrate that the formation of pure LTL phase is greatly facilitated at 150 ºC for 6 days only when using triethylene glycol (TEG) as the co-solvent, verified by powder X-ray diffraction (PXRD). SEM images show that LTL crystals present a cylinder-like structure with an aspect ratio of one. The formation of pure LTL phase is dramatically deteriorated when the synthesis conditions are changed to higher temperature (180 ºC), various synthesis durations (1-3 days) and aging time, and using other co-solvents (ethylene glycol and diethylene glycol). Inspired by published results indicating the interactions between Ge and glycols, I developed three synthesis approaches exploring the feasibility of incorporating germanium (Ge) into LTL framework using TEG in the second part of this study. Moreover, studies report that the incorporation of Ge in zeolite frameworks can enhance zeolites’ catalytic performances. The results from my investigation show that highly crystalline and well-defined LTL crystals are attained at 150 ºC for 3 days. X-ray fluorescence (XRF) shows the presence of Ge in LTL samples, indicating that the incorporation of Ge is very promising using the developed synthesis approaches. The outcomes are expected to be very useful to other researchers in the zeolites research field.