Wattana Singhto, Navadol Laosiripojana, Suttichai Assabumrungrat, and Sumittra Charojrochkul

pp. 1251 - 1264

Abstract

       The steam reforming of ethanol over Ni on Ce-ZrO₂ support, (Ni/ Ce-ZrO₂) were studied. The catalyst provides significantly higher reforming reactivity and excellent resistance toward carbon deposition compared to Ni/Al₂O₃ under the same conditions. At the temperature above 800ºC, the main products from the reforming processes over Ni/Ce-ZrO₂ were H₂, CO, and CO₂  with small amount of CH₄ depending on the
inlet ethanol/steam and oxygen/ethanol ratios, whereas high hydrocarbon compounds i.e., C₂H₄and C₂H₆ were also observed from the reforming of ethanol over Ni/Al₂O₃  in the range of conditions studied (700-1000ºC).

        These excellent ethanol reforming performances of Ni/Ce-ZrO₂ in terms of stability, reactivity and product selectivities are due to the high redox property of Ce-ZrO₂. During the ethanol reforming process, in addition to the reactions on Ni surface, the gas-solid reactions between the gaseous components presented in the system (C₂H₅OH, C₂H₆ , C₂
H₄ , CH₄ , CO₂ , CO, H₂O, and H₂) and the lattice oxygen (O_x) on Ce-ZrO₂
surface also take place. Among these redox reactions, the reactions of adsorbed surface hydrocarbons with the lattice oxygen (O_x) (C_nH_m + O_x → nCO + m/2(H₂) + O_x-n) can eliminate the formation of high hydrocarbons (C₂H₆and C₂H₄), which easily decompose and form carbon species on Ni surface (C_nH_m→ nC + m/2H₂).