1-1-2　Preparation and catalytic cracking reactivity of ZSM-5 zeolite from Vietnamese Quang Ninh coal ash

Abstract

Quang Ninh (QN) coal ash includes large amounts of Al₂O₃ and SiO₂ which can be utilized for zeolite synthesis. In this paper QN coal model ash and real ash were used to prepare ZSM-5 zeolite using tetrapropylammonium hydroxide (TPAOH) at 150oC for 48h. It was confirmed from the results of XRD patterns and nitrogen adsorption/desorption measurement that ZSM-5 crystals appeared at higher than SiO₂/Al₂O₃ ratio of 52 and developed completely at 78. The similar results were observed for ZSM-5 synthesis not only without QN coal ash components but also with model coal ash and real QN coal ash, indicating that the effects of components on the preparation of ZSM-5 would be rather small. When these zeolites were used for the catalytic cracking of low-density polyethylene (LDPE) using the Curie point pyrolyzer (CPP) method, ZSM-5 prepared using model coal ash components exhibited the same or slightly higher conversion than conventional ZSM-5. In contrast to this, ZSM-5 prepared with real coal ash components exhibited the slightly lower conversion, suggesting that the kinds of inorganic salts might affect the reactivity in catalytic cracking of LDPE.