Dry reforming of methane over Ni/Ce0.8Ti0.2O2-δ: The effect of Ni particle size on the carbon pathways studied by transient and isotopic techniques

The effects of Ni particle size (d(Ni) - 22-45 nm) of Ni/Ce0.8Ti0.2O2-delta on the carbon paths in the dry reforming of methane at 750 degrees C have been investigated by various transient and isotopic experiments. The aim was to provide new insights for improving catalyst's coke-resistance. Various correlations have been derived between dNi and (i) the initial kinetic rates (per Ni particle) of CH4 dissociation and CO disproportionation reactions along with their respective amounts of carbon accumulation, (ii) the integral rates of CH4 conversion and CO formation and the amount of carbon deposition in the DRM, and (iii) the rate of carbon removal by lattice oxygen of support compared to that by oxygen formed via the CO2 activation route during DRM. The former rate was found larger than the latter one independent of dNi (nm). CH4 dissociation is the exclusive route of inactive carbon formation during DRM independent of d(Ni).