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.