Catalytic hydroprocessing of mixed plastic waste using Ni-Ce/ZSM-5: Performance and emission analysis of diesel blends across blending ratios

Abstract

This study aims to address recycling and mitigating plastic pollution challenges by developing a sustainable fuel for transportation from post-consumer plastic waste. While the circular economy has provided solutions, the recycling process still faces unresolved challenges. This research identifies a gap in plastic combustion studies and proposes a solution by converting mixed plastic pyrolysis oil (MPO) into a diesel-like fuel that meets environmental standards. Previous research has demonstrated the potential of hydroprocessing synthetic polymers to convert plastic pyrolysis oil into transportation gasoline. However, this study focuses on the hydroprocessing of MPO using a Ni−Ce/ZSM-5 bimetal catalyst, assessing the fuel’s performance in terms of combustion and emissions in compression-ignition engines. High dispersion of metallic catalysts over ZSM-5 surface aided in efficient hdroprocessing. The study demonstrates the conversion of MPO into diesel-like fuel (HPO) under specific conditions of 70 bar H₂ and 300 °C. The resulting fuel closely resembles diesel, with n-alkanes, aromatics, and isoalkanes produced in proportions that mimic diesel composition. Blends of hydroprocessed plastic pyrolysis oil (HPO) with diesel at ratios of 20 %, 40 %, 60 %, and 80 % were tested for combustion performance in a diesel engine. Analysis of the complete range of engine performance results for the blended fuel indicated a 90 % similarity to diesel in terms of combustion and performance, as well as a 80 % similarity in emissions. The physicochemical properties of the HPO matched the IS standard for diesel fuel. The combustion of HPO in diesel engines could offer a cleaner environmental option for the disposal of waste plastics. Energy derived from waste plastics could be a viable option if it complies with regulatory requirements. This study suggests that pursuing this approach is feasible, thereby reinforcing its potential as a sustainable fuel source from plastics.