Hydrogen production from ethanol steam reforming: Effect of Ce content on catalytic performance of Co/Sepiolite catalyst

A series of Co-xCe/Sepiolite (SEP) catalysts were synthesized and evaluated in ethanol steam reforming (ESR) for hydrogen production. The properties of calcined and reduced catalysts were characterized by N-2 adsorption-desorption, XRD, H-2-TPR, XPS and HRTEM. These results indicated that Co metal dispersion and reducibility of Co-xCe/SEP catalysts were improved by Ce addition. In addition, the interaction between active metal phase and SEP support was significantly improved by Ce promoter, which could suppress the sinter and re-oxidation of Co metal phase during the catalytic test. Meanwhile, HRTEM and XPS analysis demonstrated a portion of cobalt ions incorporated into CeO2 lattice, enhanced the formation of oxygen vacancies, which could react with coke precursors on catalyst surface to remove carbon deposition. During the 4 h of ESR reaction under S/C = 3, T= 600 degrees C and WHSV= 21.5 h(-1), Co-0.3Ce/SEP (Ce/Co mole ratio = 0.3) showed the highest carbon conversion rate of 90.8% and H-2 yield of 69.1%. Combining the characterizations for spent catalysts, it was found that the unique catalytic performance of Co-0.3Ce/SEP was attributed to strong synergy effect among Co metal active sites, excellent thermostability of SEP and the formation of oxygen vacancies in CeO2. Additionally, Co-0.3Ce/SEP showed the exciting stability during 100 h on stream.