On the catalytic nature of nitrided NiMo/γ-Al2O3 catalysts for dry reforming of methane

Abstract

Nitrogen and phosphorus are one of the most common Group 15 elements. The chemistry of nitrogen and phosphorus is very important in the field of catalysis. Three types of nitride containing NiMo/γ-Al₂O₃ catalysts were synthesized using different loading-nitriding sequences and oxide precursor types for dry reforming of methane (DRM). The active components (Ni₂Mo₃N and Ni/Mo₂N) firstly reacted with CO₂, transforming into NiO and MoO₂. They were then carburized with CH₄ to produce Ni/Mo₂C during the DRM process. From that point on, a redox cycle, viz. NiO/MoO₂ ⇆ Ni/Mo₂C, occurred during the DRM reaction. The low activity of nitriding-first NiMo nitride catalyst can be attributed to bulk oxidation. The observed gradual decline in performance of loading-first Ni/Mo nitride catalyst was due to coking. Noticeably, the loading-first NiMo nitride catalyst can demonstrate superiority in both activity and resistance to coking, which was due to its strong metal–Al₂O₃ interaction and high metal dispersion.