The regulatory role of cysteine in active phase construction of polyoxometalate-based hydrodesulfurization catalysts: Reduction, chelation, and dispersion

Abstract

Polyoxometalate-based hydrodesulfurization (HDS) catalysts were modified using cysteine to construct efficient CoMoS active phase. Cysteine, characterized by chelating (–COOH, –NH2) and reducing (−SH) groups, assumed a triple role in catalyst synthesis, including reduction, chelation, and dispersion. Cysteine pre-reduced polyoxometalates to heteropoly blue, significantly increasing the catalyst sulfidation. The increased nucleophilicity of heteropoly blue enhanced their attraction to Co2+ ions, intensifying the Co-Mo bimetallic synergy. The formation of Co-chelate species delayed Co sulfidation, allowing for the concurrent sulfidation of both Co and Mo species and promoting the generation of the CoMoS active phase. Carbonaceous deposits from the high-temperature carbonization of cysteine weakened the metal-support interaction, facilitating the dispersion of the active phase. The S-CoPMo12-Cys/Al2O3 catalyst demonstrated high activity in the HDS reaction of dibenzothiophene, showcasing their potential for advanced HDS reaction.