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

Abstract

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 (Ea = 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.