Density functional theory simulation of the deoxygenation of lignite model compounds in the aqueous phase under a CO atmosphere catalyzed by OH− ions

Abstract

In this paper, the mechanism of the deoxygenation of lignite model compounds in the aqueous phase under a CO atmosphere catalyzed by OH⁻ ions was investigated at the M06-2X/6-311++G(d, p) level. The results revealed that for the deoxygenation of phenol, the activity of the H species follows H˙ > H⁻ > H⁺, and the reaction of CO with OH⁻ ions under aqueous conditions confirmed that H⁻ is the dominating active species. The study of H⁻ attacking carbon atoms at different positions on phenol indicated that deoxygenation via substitution to form benzene is preferred over hydrogenation via addition. The effect of the active species H⁻ on the deoxygenation of the lignite model compounds phenol, benzenediols, and benzenetriols was also examined. This study provides valuable information for future research on lignite deoxygenation.