Catalytic Synergy between\nLewis Acidic Alumina and\nPt in Hydrodechlorination for Plastic Chemical Recycling

Pyrolysis-based plastic chemical recycling has gained\nsignificant\nindustrial attention due to its advantage of eliminating complex plastic\nsorting processes. However, plastic pyrolysis oil contains various\ncomponents that require stringent removal before subsequent processes.\nIn particular, Cl compounds originating from the decomposition of\npoly(vinyl chloride) can cause serious corrosion of reactors and catalyst\ndeactivation in downstream processes. While extensive research has\nbeen conducted on the removal of other heteroatoms (S, N, and O) from\norganic compounds via hydrotreating, studies on the removal of Cl\nhave been scarce. In this study, hydrodechlorination over Pt catalysts\non various supports is comprehensively investigated using 1,2-dichloroethane\nas a model reactant. Our results demonstrate that Pt on γ-Al<sub>2</sub>O<sub>3</sub> can exhibit exceptionally high catalytic activity\ncompared to those on other supports due to a distinct bifunctional\nmechanism. Rigorous studies reveal that the Lewis acidic pentacoordinated\nAl sites of γ-Al<sub>2</sub>O<sub>3</sub> activate C–Cl\nbonds, whereas Pt activates H<sub>2</sub> and provides spillover H\nto remove Cl as HCl. The bifunctional mechanism enables the minimized\nuse of precious Pt (<0.1 wt %) to achieve high activity. Pt/γ-Al<sub>2</sub>O<sub>3</sub> also allows for efficient Cl removal (96.8%)\nwith high stability in treating waste plastic pyrolysis oil containing\n7500 ppm of Cl.