Unraveling the catalytic performance of RuO2(1 1 0) for highly-selective ethylene production from methane at low temperature: Insights from first-principles and microkinetic simulations

Despite significant progress in low-temperature methane (CH₄) activation, commercial viability, specifically obtaining high yields of C₁/C₂ products, remains a challenge. High desorption energy (>2 eV) and overoxidation of the target products are key limitations in CH₄ utilization. Herein, we employ first-principles density functional theory (DFT) and microkinetics simulations to investigate the CH₄ activation and the feasibility of its conversion to ethylene (C₂H₄) on the RuO₂ (1 1 0) surface. The CH activation and CH₄ dehydrogenation processes are thoroughly investigated, with a particular focus on the diffusion of surface intermediates. The results show that the RuO₂ (1 1 0) surface exhibits high reactivity in CH₄ activation (E_a = 0.60 eV), with CH₃ and CH₂ are the predominant species, and CH₂ being the most mobile intermediate on the surface. Consequently, self-coupling of CH₂* species via CC coupling occurs more readily, yielding C₂H₄, a potential raw material for the chemical industry. More importantly, we demonstrate that the produced C₂H₄ can easily desorb under mild conditions due to its low desorption energy of 0.97 eV. Microkinetic simulations based on the DFT energetics indicate that CH₄ activation can occur at temperatures below 200 K, and C₂H₄ can be desorbed at room temperature. Further, the selectivity analysis predicts that C₂H₄ is the major product at low temperatures (300-450 K) with 100 % selectivity, then competes with formaldehyde at intermediate temperatures in the CH₄ conversion over RuO₂ (1 1 0) surface. The present findings suggest that the RuO₂ (1 1 0) surface is a potential catalyst for facilitating ethylene production under mild conditions.