(Invited) Quantum Mechanical Screening of Metal-N4-Functionalized Graphenes for Electrochemical Anodic Oxidation of Light Alkanes to Oxygenates

Abstract

Developing processes that allow partial oxidation of light alkanes (C1-C4) to more valuable oxygenates is important from both industrial and academic perspectives. In this study, quantum mechanics combined with a constant potential model were employed to evaluate the ability of metal-N4-functionalized graphene (gMN4) to catalyze anodic partial oxidation of light alkanes to oxygenates via electrochemical means while considering both the reactivity and selectivity. During the reaction, reactive oxo (*O) is generated through water electrochemical oxidation. This reactive oxo is used to oxidize light alkanes (represented by methane and propane). Based on investigating the systems with different Ms (Cr, Mn, Fe, Co, Ru, Rh, Os, and Ir) in a wide range of electrode potentials (U, 0.0 to 2.0 VSHE) and pH values (0.0 to 14.0), only gIrN4 and gFeN4 were capable of catalyzing this oxidation with acceptable reaction rates. The other catalysts were unable to form *O or inert to C-H bonds. Both alkanes can be oxidized but the rate for methane is slower. gIrN4 oxidizes methane to formaldehyde under proper Us. For propane, this catalyst generates iso-propanol at low Us and acetone at high Us. gFeN4 only oxidizes propane to acetone. Our theoretical investigation along with known experimental results suggest a high probability for experimental realization of this anodic partial oxidation, which would allow for utilization of natural gas discovered in remote oil fields.