H2 Production from Partial Oxidation of iso-Octane over Ni/Ce0.75Zr0.25O2 and Ni/β- Al2O3 Catalysts

In this study, the partial oxidation of iso-octane over Ni/Ce0.75Zr0.25O2 and Ni/β”Al2O3 catalysts was investigated. The results indicated that Ni/Ce0.75Zr0.25O2 is more active than Ni/β”-Al2O3. The partial oxidation products are mainly H2 and CO for Ni/Ce0.75Zr0.25O2 with hydrogen selectivity up to 85%. The H2/CO ratio is in the range of 1.3-2.0 depending on the operating temperature. It was noticed that at temperature above 700C, the presence of methane was detected. On the other hand, the main products of iso-octane partial oxidation over Ni/β”-Al2O3 are CO2 and i-C4H8 at temperature below 650C. Above 650C, the main products are H2 and CO. The H2/CO ratio is about 1.3. However, the hydrogen selectivity was found to be lower than that of Ni/Ce0.75Zr0.25O2 due to the formation of other hydrocarbons such as CH4, C2H4, C2H6 and C3H6. These hydrocarbons are the products of catalytic cracking of iso-octane and methane coupling. The reaction mechanism of iso-octane partial oxidation over Ni/β”-Al2O3 catalyst might be explained by β-elimination. For both catalysts, the hydrogen and carbon monoxide selectivity was found to decrease with increasing C/O ratio. The Ni/Ce0.75Zr0.25O2 catalyst can be operated in a wider range of C/O ratios than the Ni/β”-Al2O3 catalyst.