(532z) Role of Solid Acid in Low-Temperature Hydrocracking of Polyolefins to Fuels
AIChE Annual Meeting
2022
2022 Annual Meeting
Catalysis and Reaction Engineering Division
Poster Session: Catalysis and Reaction Engineering (CRE) Division
Wednesday, November 16, 2022 - 3:30pm to 5:00pm
Several solid acids were used in this study to elucidate the effect of acid strength, concentration and site accessibility on outcome of hydrocracking. Zeolites BEA, MOR, FAU, MFI, mesoporous Al-MCM-41, WO3/ZrO2 were doped with 0.5% Pt as metal component. Reaction was performed in batch system under stirring at 250 °C at different H2 pressures. Zeolites were modified using desilication. This enables us to compare zeolites with similar acid sites concentration and different porosity.
Our results show that major faction in zeolite-catalyzed hydrocracking is interpore diffusion constraints. Medium-sized reaction intermediates cannot escape porous network without further cracking to small C5-C7 fraction. Upon introduction of relatively narrow 3-4 nm mesopores in FAU zeolite the yield of C13+ alkanes drastically increases. In case of zeolites, initial polymer binding occurs mainly on the outer surface of zeolite crystal.
Our findings provide a blueprint for further improvement in plastic waste hydrocracking and it shows how tailoring of acid component can drastically change overall activity and selectivity.