The partial oxidation of propane is a useful surrogate for the reforming of gasoline to produce hydrogen in-situ for transportation. Hydrogen production over CeO2-supported Pt was compared to the process using Ni/CeO2 catalysts. The aim of the study was to investigate the sequence of different reactions during propane oxidation over the two catalysts and to determine optimum methods of producing hydrogen in each case. The effect of space velocity on the reaction rates was evaluated by varying total inlet flow (100 to 400 SCCM) and catalyst weights. At 600 °C, six species (C3H8, O2, H2, CO, CO2 and C3H6) were detected at the reactor outlet. The Gaussian elimination process yielded four independent reactions. This resulted in ten sets (which would yield the six species). For each set, a material balance on the six outlet compositions measured obtained the extents of each of the four reactions in the set. The rate of each reaction in all the ten sets was calculated using a least-squares-regression technique. Sets were eliminated from consideration if they contained irreversible reactions with negative rates. To confirm the validity of sets containing dry reforming, steam reforming and water gas shift, these reactions were further carried out over the catalysts. Finally, the effect of weight hourly space velocity on the reaction rates for each of the catalyst was evaluated. This allows us to evaluate the relative importance of each reaction in each allowable set as a function of contact time.
The results indicate that, for Pt-based catalysts, hydrogen production is supported through the exothermic direct partial oxidation route at the lowest contact times. On the other hand, for Ni-based catalysts, hydrogen production can be maximized by using higher contact times, and it supports the endothermic steam reforming reaction.