Synthesis and characterization of Li-type EDI zeolite

A Li-type EDI zeolite (Li-EDI) was successfully synthesized in the Li2O–Al2O3–SiO2–H2O system using a silica–alumina mixed sol as the starting material in the absence of other chemical species. The characterization of the obtained Li-EDI was compared with that of the Li-exchanged Linde F zeolite (K-type EDI zeolite). Starting gels with the batch composition of xLi2O·Al2O3·2SiO2·275H2O (x = 2–5) were prepared by adding a LiOH solution to a silica–alumina mixed sol. A hydrothermal reaction of the gels was carried out at various temperatures. Li-EDI formed from all of the batches in the range of 60–100 °C. However, the ABW-type zeolite co-crystallized in the composition of Li2O/Al2O3 of 2.0–3.0 above 90 °C. The crystal morphology of Li-EDI was a prism shape. The average particle size of Li-EDI is 0.69 μm in length and 0.23 μm in width. The crystal structure of the Li-EDI collapsed at 300 °C, which indicated that the thermal stability of Li-EDI is significantly lower than that of the Linde F zeolite, which is stable up to 1000 °C.