Zeolite synthesis directly from alumatrane and silatrane via sol-gel process and microwave technique

Abstract

Zeolites or crystalline aluminosilicate are successfully synthesized directly from alumatran and silatrane by sol-gel process using metal hydroxide: lithium, sodium or potassium hydroxide as hydrolytic agent and hydrothermal crystallization using microwave-heating technique. Hydrolysis rate in the sodium hydroxide system is approximately two times faster than that of sodium chloride system and crystallization occurred only in alkali base solution. For each metal hydroxide system, temperatures using for transforming to crystalline aluminosilicate are different. Potassium hydroxide system requires higher energy orderly as measured by DSC, and temperature than sodium and lithium hydroxide. Different hydrolytic agent resulted in different crystal, microwave heating temperature and time. Pure and nice crystal products are obtained with small particle size distribution. Varying Si:A1 ratio mostly affected the type and morphology of synthesized product while varying metal hydroxide concentration mostly affected reaction time and crystal morphology. In case of lithium hydroxide, its concentration also influences on the type of synthesized product. Increasing water content ratio reduces the overall concentration and rate of nuclei generation.