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The amount of carbon formed and the H2/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 H2/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 H2/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.

The effect of the distribution of CeO 2 -ZrO 2 on Ni/MgAl 2 O 4 catalyst on the catalytic performance during the combined steam and carbon dioxide reforming of CH 4 (CSCR) was investigated on two different catalysts prepared using a sequential impregnation and co-precipitation of Ni and CeO 2 -ZrO 2 components. The CeO 2 -ZrO 2 plays an important role in the CO 2 conversion by enhancing a facile activation of CO 2 with an adjacent contact with nickel crystallites. The CSCR catalysts prepared by the co-precipitation of nickel and CeO 2 -ZrO 2 on MgAl 2 O 4 support shows a catalytic activity superior to the catalyst prepared by sequential impregnation of nickel on the MgAl 2 O 4 support with CeO 2 -ZrO 2 due to the homogeneous distribution of CeO 2 -ZrO 2 with the formation of small nickel crystallites and a large amount of active sites for CO 2 adsorption.

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