Effects of Carbon Formation on Catalytic Performance for CO2 Reforming with Methane on Ni/Al2O3 Catalyst: Comparison of Fixed-Bed with Fluidized-Bed Reactors

The amount of carbon formed and the H-2/CO molar ratio for the carbon dioxide reforming (CDR) reaction with methane were investigated on Ni/Al2O3 catalyst using a laboratory-scale fixed-bed reactor and a bench-scale fluidized-bed reactor. A significant suppression of carbon deposition in the fluidized bed reactor compared with the fixed bed reactor can be mainly induced from different product gas flow patterns by the continuous circulation of catalysts in oxidizing and reducing regions. This, approach also enhances the gasification rate of deposited carbon in an expanded catalyst bed by increasing the amount of water adsorbed. The higher H-2/CO ratio above 1.0 in the fluidized-bed reactor is also attributed to the enhanced gasification rate of deposited carbon precursors. The differences in the conversions of CH4 and CO2 and the H-2/CO ratios in the two reactors are responsible for the different competitive rates of the reverse water-gas shift (RWGS) reaction, the Boudouard reaction, and the gasification of carbon precursors.