Mechanistic and microkinetic insights into the stability and activity of Ni3In catalyst for dry methane reforming

Dry methane reforming (DMR) reaction has garnered significant attention for its potential in consuming CO2 for environmental sustainability, as well as utilizing CH4 as a fossil resource with the highest hydrogen content. In-depth understanding the reaction mechanism with microkinetic modeling is essential for suppressing coke deposition and improving the stability of Ni catalysts. This study investigates the reaction intermediates and pathways of DMR on Ni3In alloy, which has been previously identified by theoretical high-throughput screening and experimental results as having improved resistance to carbon accumulation. Energetic profiles, determined through density functional theory calculations, reveal that the Ni3In catalyst exhibits an increased formation barrier for C* and lower adsorption strength compared to pure Ni catalyst. Microkinetic analysis using the CatMAP package demonstrates significantly lower carbon coverage on Ni3In than Ni catalysts. Importantly, the dissociation of CO2 plays a critical role in influencing the rate of CO formation, particularly at higher reaction temperatures. Furthermore, through flux analysis, we have identified the main reaction pathways for CO formation and highlighted the multiple pathways for oxidizing carbon-containing species to suppress carbon deposition on Ni3In catalyst. These findings not only provide theoretical support for the experimental stability of Ni-In catalysts but also offer valuable insights for the rational design of other Ni-based bimetallic catalysts employed in DMR reactions.