Novel highly active and stable alumina-supported cobalt nitride catalyst for dry reforming of methane

Dry reforming of methane (DRM) was an important reaction for the utilization of two greenhouse gases (CH4 and CO2) as feedstocks. The development of non-precious metal catalysts has been widely studied for DRM in recent years. In the present study, non-precious metal nitrides Mo2N/γ-Al2O3, Co3Mo3N/γ-Al2O3 and Co4N/γ-Al2O3 were used as catalysts for DRM. Noticeably, the catalytic performance of monometallic nitride of Co4N was evaluated in DRM for the first time. It was found that the Co4N/γ-Al2O3 catalyst was more active and stable than Mo2N/γ-Al2O3 and Co3Mo3N/γ-Al2O3 in current DRM reaction, which was probably due to the fact that the contribution of noble metal type mechanism to DRM activity on Co4N/γ-Al2O3 was much more dominant than that on Mo2N/γ-Al2O3 and Co3Mo3N/γ-Al2O. Furthermore, it can show superior DRM performance over literature reported interstitial compounds (e.g. MoP, NiMoNx and Ni/Mo2C) and exhibit competitive activity in comparison with Ni-based or noble metal-based catalysts. Interestingly, the carbon deposition behavior of the Co4N/γ-Al2O3 catalyst was greatly dependent on WHSV and reaction temperature. The amount of carbon deposition increased with the decrease in WHSV, but decreased with the increase in temperature. This was probably due to the fact that the dissociation rates of CH4 and CO2 on the catalyst were directly related to these reaction conditions. Finding appropriate reaction conditions for matching between CH4 dissociation rate and CO2 dissociation rate as close as possible was of vital importance for the long-term stabilization of Co4N/γ-Al2O3 catalyst.