Catalytic co-pyrolysis of woody biomass with polypropylene: Effects of Korean loess hybrid catalysts and pyrolysis temperatures

Abstract

This paper describes an effort to improve the catalytic characteristics of Korean loess (KL) for the co-pyrolysis of biomass and polypropylene, resulting in a unique multifunctional catalyst. Korean loess was physically and chemically transformed into a microporous structure (ZSM) fitting for co-pyrolysis. Using the catalysts manufactured above, analytical co-pyrolysis was carried out using a Py-GC/MS system with pinewood sawdust and polypropylene mixed at a ratio of 1:1 (w/w). To investigate the impacts of the use of catalysts and the pyrolysis temperatures on the distribution of volatile pyrolytic products, the experiments were designed to mix 2- or 8-fold catalyst mass quantities with feedstock and pyrolyze at temperatures of 500 °C, 600 °C, and 700 °C. Compared to pure Korean loess, the catalytic activity of the optimal hybrid catalyst (0.2KL/ZSM) favored decarbonylation over dehydration, making it more effective than mesoporous ZSM. Pyrolytic products generated using the hybrid catalyst (0.2KL/ZSM) had a higher hydrogen concentration (9.8 wt%) than pyrolytic products produced using ZSM catalysts (6.5 wt%). Because of this, the pyrolytic products were expected to be more compatible as a fuel over 0.2KL/ZSM, with an HHV of 27.4 MJ/kg as opposed to 26.5 MJ/kg over ZSM. Zeolite framework catalysts could promote the production of aromatic chemicals (3.0 mg/g for non-catalyst, 34.7 mg/g for KL, and 53.9 mg/g for 0.2KL/ZSM) in the co-pyrolysis of PP with pine, which synergistically enhance oligomerization, cyclization, and aromatization reactions at catalyst acid sites. Concerning aromatic hydrocarbon yields, 0.2KL/ZSM could be expected to perform very similarly to ZSM in producing 74.7 mg/g of MAH+PAH at 600 °C.