Role of Support in CO2Reforming of CH4to Syngas over Ni Catalysts

Abstract

The dynamic changes in activity and selectivity for the CO2reforming of CH4over unsupported and supported Ni catalysts were investigated. The reduced NiO has low initial conversions of CH4and CO2, which decrease rapidly with time. The mixture of powders of NiO and Al2O3has low initial conversions of CH4and CO2and a low yield to CO, which, however, increase with reaction time, due most likely to Ni migration to Al2O3. In contrast, the reduced 1 wt% Ni/Al2O3catalyst (reduced from NiO/Al2O3) has high initial conversions and CO yield, which slowly decrease with time due to carbon deposition. The reduced 13.6 wt% Ni/Al2O3catalyst has high initial conversions and CO yield, but, because of carbon deposition, the reactor was completely plugged in 6 h. The reduced 1 wt% Ni/SiO2catalyst has moderate initial activity and CO yield, which decay fast with reaction time. The reduced 13.6 wt% Ni/SiO2has a high initial activity and CO yield, which decay slowly with reaction time. The reduced 13.6 wt% Ni/TiO2has a moderate initial activity and CO yield, which decay with reaction time. Carbon deposition was found to occur over all these catalysts, and the sequence of carbon deposition was: 13.6 wt% Ni/Al2O3>13.6 wt% Ni/SiO2>the reduced mixture of NiO and Al2O3(13.6 wt% Ni)>13.6 wt% Ni/TiO2>1 wt% Ni/Al2O3>1 wt% Ni/SiO2.