Lewis Acid Site Engineering in MOF‐Derived Aluminum Oxide/Carbon Composites for Dechlorination of Waste Plastic Pyrolysis Oil

ABSTRACT

Chemical recycling of waste plastics is a key route toward a circular economy, yet organochlorine impurities in waste plastic pyrolysis oil (WPPO) hinder its valorization by causing equipment corrosion and catalyst deactivation. Here, we report a defect‐engineering strategy that enriches coordinatively unsaturated Al sites through the controlled carbonization of an aluminum‐fumarate metal–organic framework. Partial decomposition of the fumarate linkers generates an aluminum oxide/carbon composite with abundant accessible Lewis acid sites, whose density can be tuned through the carbonization temperature. The optimized adsorbent, MDAC 600, effectively captured chemically diverse organochlorines (paraffinic, olefinic, naphthenic, and aromatic organochlorines) and reached an adsorption capacity of up to 11.09 mg g ^{− 1} in real WPPO, outperforming both the parent framework and a commercial sorbent. Pyridine‐FTIR, NH ₃ ‐TPD, molecular dynamics, and density functional theory analyses consistently attributed this performance to favorable Lewis acid–base interactions between the undercoordinated Al sites and organochlorine molecules. Notably, pelletized MDAC 600 sustained continuous fixed‐bed dechlorination of a 1 L WPPO feed with an adsorption capacity of 8.80 mg g ^{− 1} and retained its performance over repeated regeneration cycles. This work establishes a scalable adsorption platform for continuous dechlorination of high‐chlorine, authentic WPPO and provides a basis for multistage treatment toward refinery specifications.