Catalytic Pyrolysis of Polypropylene Waste for Production of Aromatics and Light Hydrocarbons in a Reactive Distillation System

Production of value-added chemicals, such as light olefins and monoaromatics, by plastic waste pyrolysis represents a promising upcycling pathway that would contribute to overcoming low recycling rates. However, the broad pyrolysis product distribution spanning a wide carbon number range (up to C60) hinders downstream conversion to specific chemicals. This work demonstrated high yields of light olefins and monoaromatics from polypropylene (PP) pyrolysis using a novel batch catalytic reactive distillation system. The design involves the reflux of heavier fractions, extending their residence time in the reaction zone and therefore enhancing PP conversion and selectivity. After tuning the temperature and PP to HZSM-5 zeolite catalyst ratios, nearly all PP was converted to products with carbon numbers less than C12. Moreover, among the limited pyrolysis research on reactive distillation, this study is the first to report aromatics, in particular, BTEX (benzene, toluene, ethylbenzene, and xylenes), whose yield increased compared to a control experiment without reflux.