| 초록 |
DFT and microkinetic modeling are used to study CH4 oxidation on Pd(111) under mildly oxidizing conditions. Although our energetic analysis indicates that metallic sites are more active than O* and OH* sites for C–H bond activation, our microkinetic analysis indicates that metallic sites produce mostly CO, whereas O* sites produce mostly CH2O. However, the product selectivity can change greatly depending on product pressures. Increasing product pressures leads to the promotion of CO2 production, because CO oxidation is much more active than CH4 oxidation. We then extend the study to other FCC(111) surfaces by incorporating the scaling relations in the microkinetic model. We find that most transition-metal surfaces cannot effectively activate CH4 under the reaction conditions employed. Finally, CH4 oxidation kineitcs is described as functions of two descriptors, enabling identification of promising catalyst surfaces for selective production of the desired product. |
