Sustainable CO2 fixation under low CO2 pressure, solvent free conditions using a recyclable Zn-dehydroacetic acid catalyst supported on SBA-15

A heterogeneous catalyst has been synthesized by immobilizing a zinc complex of the bio- derived dehydroacetic acid (DHA) ligand onto SBA-15. This catalyst was characterized by BET, XPS, FTIR, TGA, TEM, SEM, XRD, and ICP-OES, which confirmed the successful incorporation of Zn-DHA complex into the SBA-15. In combination with KI (3 mol%) as simple and inexpensive co-catalyst, the minimal amount (20 mg) of the catalyst, promoted the solvent free cycloaddition of CO₂ to epoxides at 50 °C under ambient to low CO₂ pressure (2 bar to balloon). This mesoporous catalyst exhibited excellent activity and selectivity across a broad substrate scope and could be reused for six cycles, with minimal loss in performance. Hot filtration test and ICP analysis confirmed the structural stability and heterogeneous nature of the catalytic process with negligible leaching. A key distinguishing feature of this catalyst is the modulation of Lewis acidity at Zn(II) center by the oxygen-rich DHA ligand, promotes catalyst dispersibility and improves epoxide activation. Notably, this cost-effective and reusable catalyst system avoids high CO₂ pressure and costly quaternary ammonium salts, significantly improving sustainable CO 2 valorization and practical applicability. • Heterogeneous catalyst by immobilizing a zinc complex of dehydroacetic acid (DHA) ligand onto SBA-15 was synthesized. • Zn-DHA@SBA-15/ KI system promoted the solvent free cycloaddition of CO₂ to epoxides at ambient temperature. • Catalyst showed high activity and selectivity under ambient CO₂ pressure and quaternery salt free co-cataysts. • Catalyst reused for six cycles, with minimal Zn-DHA leaching or loss in performance.