Characterization and catalytic activities of faujasites synthesized by using coal fly ash

Coal combustion by-product fly ash was converted selectively into faujasite (Y type) zeolite and was used as a catalytic material. The conversion proc ess tried to alleviate the disposal problem of large amounts of fly ash, an d turned fly ash into useful materials. Fused fly ash powder and supernatan t were used in the synthesis of Y type zeolite. The prepared Na-Y zeolites were characterized and ion-exchanged followed by calcinations to obtain H-Y . The catalytic properties of the solid obtained were evaluated using cumen e cracking and compared with those of commercially available (standard) zeo lites. It was found that most of the Si and Al components in the fly ash co uld be effectively transformed into Y type zeolite in the presence of seeds but not the mineral phase, such as mullite. Moreover, the supernatant of t he fused powder solution can produce purer faujasites and the sediment can be reused to generate solution for the further preparation of zeolites. Inv estigation by NMR demonstrated that fusion plays an important role in enhan cing the hydrothermal conditions for zeolite synthesis. The H-Y zeolite der ived from the supernatant of fly ash solution shows excellent cracking acti vity compared to that of standard.