Potential of intrinsic reactivity toward value added products from methane oxidation on RhO2(1 1 0) surface

Abstract

Catalytic studies focusing on the direct transformation from methane (CH4) to value-added products have attracted considerable attention due to the dramatic increase in natural gas production. This study investigated computationally and experimentally the potentials of intrinsic reactivity for RhO2(110) surface toward value-added products (C2H4 and CH2O) from methane oxidation. The simulation predicted that RhO2(110) is capable of low-temperature methane activation, but it is less active than IrO2(110), which has superior reactivity toward methane, leading to complete oxidation. In addition, the complete oxidation of methane was computationally predicted to be facile, and the results were validated by In-situ DRIFT experiments showing multiple intermediates of methane oxidation. Finally, the potential mechanism for C–C coupling was evaluated to produce the value-added product of C2H4 from CH4 oxidation on RhO2(110) surface. These results showed that the reaction kinetics of C2H4 formation is competitive with the further oxidation, which is the opposite kinetic behavior of IrO2(110). The results suggest that the RhO2(110) surface has a high potential to effectively produce the value-added product because of the low-temperature activation preventing the acceleration of further oxidation and the competitive reactions (production of value-added product vs. further oxidation). With the proper strategy, hindering further oxidation (deactivation of surface oxygens), and the moderate reactivity of RhO2(110), the additional enhancement in the selectivity toward value-added products would be achieved.