Non-thermal plasma for process and energy intensification in dry reforming of methane

Plasma-assisted dry reforming of methane (DRM) is considered as a potential way to convert natural gas into fuels and chemicals under near ambient temperature and pressure; particularly for distributed processes based on renewable energy. Both catalytic and photocatalytic technologies have been applied for DRM to investigate the CH4 conversion and the energy efficiency of the process. For conventional catalysis; metaldoped Ni-based catalysts are proposed as a leading vector for further development. However; coke deposition leads to fast deactivation of catalysts which limits the catalyst lifetime. Photocatalysis in combination with non-thermal plasma (NTP), on the other hand; is an enabling technology to convert CH4 to more reactive intermediates. Placing the catalyst directly in the plasma zone or using post-plasma photocatalysis could generate a synergistic effect to increase the formation of the desired products. In this review; the recent progress in the area of NTP-(photo)catalysis applications for DRM has been described; with an in-depth discussion of novel plasma reactor types and operational conditions including employment of ferroelectric materials and nanosecond-pulse discharges. Finally, recent developments in the area of optical diagnostic tools for NTP, such as optical emission spectroscopy (OES), in-situ FTIR, and tunable diode laser absorption spectroscopy (TDLAS), are reviewed.