Catalytic co-cracking of biomass and waste plastics with sawdust mediated ZSM-5 synthesized via activating gel process

Abstract

Minimizing the catalyst cost is critical to achieving long-term economic feasibility for obtaining bio-chemicals directly from biomass. In the present study, low cost ZSM-5 was synthesized via hydrothermal crystallization of the activated aluminosilicate gel without adding any organic ammonium templates and additional seed crystals. The activation process promoted the depolymerization of the silica-alumina species and the formation of active pasty gel containing nucleation precursors, consequently accelerating the subsequent crystallization reaction. The addition of eucalyptus sawdust (ES) in the synthesis process increased the BET (Brunauer-Emmett-Teller) surface area and acidity of the resultant zeolites. The ES-mediated ZSM-5 (AGZ-10) achieved a higher benzene, toluene, ethylbenzene and xylene (BTEX) carbon yield (18.9 %) from co-cracking of ES and waste plastics (WP) (ES/WP mass ratio at 1:1) at 500 °C and exhibited better synergistic effect and anti-coking ability compared to the commercial ZSM-5. The results provide an efficient synthetic strategy to produce low-cost zeolites, and a promising technique to effectively utilize biomass and plastic wastes.