Two-Step Heating Process for the Synthesis of Zeolite Na-Y from Coal Fly Ash

Abstract

A Two-step heating process for the crystallization of zeolite Na-Y from coal fly ash is investigated with emphasis on the change in the crystallinity of the synthesized zeolite Na-Y. Most of the Si and Al components are effectively transformed into zeolite Na-Y by the first conventional heating, and then the second microwave heating of synthesis mixture dissolves from coal fly ash, and the maximum crystallinity of zeolite Na-Y obtained is 95%. The first conventional heating also plays an important role in enhancing the nuclei formation that Si and Al in the synthesis mixture reacted to form ring-like structures for combining sodalites, and further to small zeolite Na-Y seeds. The second microwave heating increases the crystallization rates from small zeolite Na-Y nucleis to more zeolite Na-Y crystals. The cation exchange capacity (CEC) of the zeolite Na-Y crystallized by the two step heating process is 139.98 meq/100 g compared to 137.59 meq/100 g for commercial zeolite Na-Y. Test results showed that BET surface area and moisture absorption capacity of zeolite Na-Y synthesized from fly ash is about 839 m2/g and 0.3693 g H2O/g sample, respectively, similar to commercial zeolite Na-Y.