Fe-Doped γ-Al₂O₃ Catalysts Derived from Waste PET and Cans for Selective COS Hydrolysis

Waste PET bottles, aluminum cans, and tinplate cans were successfully upcycled into Fe-doped γ-Al2O3 catalysts via a one-pot hydrothermal process, followed by calcination. The resulting Fe/Al2O3-f catalyst exhibited a mesoporous structure with uniformly dispersed Fe species and enhanced surface basicity. Comprehensive characterization confirmed the stable incorporation of Fe into the alumina lattice, contributing to a high structural integrity and abundant reactive sites. Catalytic tests showed nearly complete COS conversion and H2S selectivity at 400 °C under optimized water vapor concentration, with excellent stability maintained over 24 h. Kinetic analysis revealed a low apparent activation energy of 21.89 kJ/mol, indicating a favorable energy profile for the COS activation. Postreaction XPS analysis verified the retention of Fe3+ species, surface hydroxyl enrichment, and minimal sulfate accumulation, supporting a Langmuir–Hinshelwood mechanism involving coadsorbed COS and hydroxyl groups. This study provides a scalable and sustainable approach for fabricating high-performance catalysts from municipal solid wastes, offering a low-cost solution for sulfur-containing gas purification and advancing circular economy practices in environmental catalysis.