Impact of acid-modified ZSM-5 on hydrocarbon yield of catalytic co-pyrolysis of poplar wood sawdust and high-density polyethylene by Py-GC/MS analysis

Abstract Co-pyrolysis of poplar wood sawdust and high-density polyethylene at a mass ratio of 1:1 (wt.%) over acid-modified ZSM-5 was studied by Py-GC/MS at catalyst to feedstock mass ratio of 1:1 (wt.%) to enhance hydrocarbon formation in the pyrolytic vapour. Catalysts were modified by wet impregnation using sulfuric acid (0.1 M, 0.3 M, 0.5 M and 0.7 M). Results showed that acid treatment affects the catalytic activity of ZSM-5 by changing the amount of acid sites. Co-pyrolysis with HDPE resulted in high olefin relative content (53.32%) than pyrolysis of poplar (16.6%) and significantly reduces the amount of oxygenates except alcohol. In catalytic co-pyrolysis over acid-modified ZSM-5, the share of olefin was between 56.20% and 59.7%, whereas the lowest amount was 49.53% over P-ZSM-5. The alkane relative content over acid-modified ZSM-5 was in the range of 23.29–25.96% and higher than that with P-ZSM-5 (21.18%). Importantly, ZSM-5 (0.5 M) was most selective for aromatic hydrocarbon (12.72%), leading to the maximum share of hydrocarbon of 93.18% when the lowest value was 76.84% over parent ZSM-5. Furthermore, ZSM-5 (0.5 M) showed better deoxygenation among catalysts used in this study. This research could be suggested as a reference for the research of co-pyrolysis of biomass and plastic.