Effect of the water–ethanol molar ratio in the ethanol steam reforming reaction over a Co/CeO2/MgAl2O4 catalyst

A Co/MgAlO catalyst with Ce addition was prepared and characterized by different techniques (BET, XRD, SEM-EDX, TPR and TG-TPO). Its catalytic performance was tested in the ethanol steam reforming reaction at 650 °C and a  = 50 g min mol using different HO:CHOH molar ratios (MR) in the feed. The presence of Ce on the catalyst markedly increased selectivity of hydrogen (from 3.2 to 5.2 molH/molCHOH for MR = 4.8) and carbon resistance. The increase of the HO:CHOH MR led to a significant decrease in the CO/CO ratio (from 0.84 for RM = 4.8 to 0.5 for RM = 8) and in the carbon amount after 7 h on stream (from 22.9 % for RM = 4.8 to 6.8 % for RM = 8). MR higher than 6 did not significantly improve the catalytic performance. Taking into account previous studies about the thermal balance of this reaction, the optimum MR in the ethanol steam reforming seems to be around 6. The ethanol conversion was nearly constant after 7 h in spite of the carbon amount detected by TG-TPO and SEM-EDX. It could be inferred that an important Co fraction was exposed on the filament tips and/or a fraction of carbonaceous species was deposited on the support surface.