Transforming red mud into an efficient Acid-Base catalyst by hybridization with mesoporous ZSM-5 for Co-pyrolysis of biomass and plastics

Abstract

• The transformation of waste red mud into highly effective catalysts is presented. • Pyrolysis of biomass and polyethylene was catalyzed by hybrid red mud/ZSM-5. • The hybrid red mud/ZSM possesses superior catalytic activity than mesoporous ZSM-5. • The hybrid catalysts can produce bio-oil with lower acidity and oxygen content. This work reports the development of a novel multifunctional catalyst by modifying the catalytic properties of red mud (RM) for the co-pyrolysis of biomass and polyethylene. This innovative catalyst design enables rearranging of the agglomerated phases in red mud, such as sodalite, into a new active and well-distributed structural framework (Meso-ZSM). The optimum hybrid catalyst (0.4-RM/ZSM) exhibits higher porosity (ten times more porous than the pristine RM), more accessible pores, and new weak basic sites compared to conventional RM. In addition, it also shows a higher catalytic activity than mesoporous ZSM-5 (Meso-ZSM) in promoting decarbonylation over dehydration. The hydrogen content of the produced oil over the hybrid catalyst (0.4-RM/ZSM) is 10.1 wt% compared to 7.8 wt% over the Meso-ZSM catalyst. Consequently, this increases the H / C eff of the oil over 0.4-RM/ZSM to 1.28 compared to 0.9 over Meso-ZSM, making it a more compatible fuel.