Advances in the direct conversion of CH4 and CO2 into acetic acid over bimetallic catalysts supported on H-ZSM-5

Abstract

This study developed heterogeneous catalysts composed of ZnO and CeO₂ supported on H-ZSM-5 for the direct conversion of methane (CH₄) and carbon dioxide (CO₂) into acetic acid. The acid–base and electronic properties were modulated through oxide impregnation and reduction, aiming to create active sites capable of simultaneously activating both reactants. The samples were characterized by XRD, N₂ physisorption, HRTEM/EDS, NH₃-TPD, CO₂-TPD, TPR, FTIR, XPS, CO₂-DRIFTS, and TGA, and tested in a batch reactor at 300 °C and 10 bar. The catalyst lifetime was evaluated through stability testing. The zeolite framework was preserved, although its properties were modified, resulting in improved CH₄ and CO₂ activation. The reduced catalyst exhibited a high surface area and an efficient distribution of acidic and basic sites, achieving an acetic acid productivity of 1473.40 µmol g⁻¹ h⁻¹ and a conversion rate of 35.12%. The results surpassed those of previous studies, highlighting the potential of the Zn–Ce/H-ZSM-5 system for biogas valorization and greenhouse gas mitigation.