Species and temperature profiles in a differential sphere bed reactor for the catalytic partial oxidation of n-octane

A method is developed by which temperature and species profiles are measured for the catalytic partial oxidation (CPO) of n-octane in a differential manner in a fixed bed of Pt and Rh-coated a-alumina spheres with a minimum resolution of I mm (or similar to 0.4 g) of catalyst over a wide range of feed stoichiometries. Results indicate that two regions of catalytic activity are present in the bed: a short (similar to 1 mm) oxidation zone in the front of the bed and a longer reforming zone downstream. The lengths of the reforming and oxidation zones are dependent on the stoichiometry of the reactor feed. O-2 is consumed rapidly on both Rh and Pt catalysts; however, full O-2 conversion is reached faster on Rh than on Pt. Both steam reforming and dry (CO2) reforming are observed in the bed downstream of the oxidation zone, but steam reforming is more extensive because higher conversions of H2O are observed than CO2 on both Rh and Pt catalysts. The conversion of H2O and CO2 in the reforming zone is always higher on Rh than on Pt, therefore Rh is a better reforming catalyst than Pt. Low molecular weight hydrocarbons like methane and ethylene are more readily reformed than octane. Results also indicate that alumina sphere beds are better supports for syngas production than alumina foam monoliths. (c) 2007 Elsevier B.V. All rights reserved.