Influence of catalyst shape on plasma-assisted dry reforming of methane: A comparative study of Ni-CeO2 nano-cubes and nano-octahedra

This study investigated the performance of 10 wt% Ni-CeO2 nano-cubes (NC) and nano-octahedra (NO) shaped catalysts in plasma-assisted dry reforming of methane (DRM) environment to understand the influence of catalyst morphology on catalytic activity and global reaction pathway. The presence of different exposed crystal planes (i. e., (111), (110), and (100)) in the CeO2 shapes led to varied NiOx-CeO2 interactions, with the NO-shaped catalyst exhibiting a higher oxygen vacancy concentration, lattice defects, and moderate basic sites compared to the NC catalyst. This interaction in the plasma DRM environment significantly enhances conversions for both shaped catalysts, with the effect more pronounced in the case of the NO-shaped catalyst. The performance data suggest that running plasma DRM at moderate temperature and higher plasma power is relatively efficient. Increasing temperatures or plasma power diverts the DRM reaction towards more H2 production, reducing CO production for both shaped catalysts. This confirms the crucial role of the catalyst in controlling the global reaction pathway considering plasma power or temperature enhancement. Plasma interactions create additional surface defects during the DRM reaction, and defect concentration is closely linked to catalyst morphology. Carbon deposits on the catalyst surface can be readily removed via CO2 plasma regeneration treatment without affecting catalyst performance. Additionally, prolonged plasma exposure leads to NiO phase separation into concentrated Ni, suggesting a cyclical DRM and regeneration approach rather than a continuous reaction.