Kinetics and Modeling of the Flexible Fuel Reformer: n-Hexadecane Steam Reforming and Combustion

Steam reforming of liquid hydrocarbon fuels provides one possible solution for the production of hydrogen for solid oxide fuel cells (SOFCs). However, the design of the reformer is dependent on the kinetics of the catalytic reaction, which is not widely reported. Because reforming is highly endothermic, we have investigated the use of a heat exchange device, designated the flexible fuel reformer (FFR), as a reactor in which combustion and reforming can be simultaneously accomplished. In the present study, we evaluated the reforming and combustion kinetics of n-hexadecane (used as an analog for diesel) over the rhodium/nickel catalyst supported on alumina. Reforming data obtained over the temperature range of 500-750 degrees C was compared against three different mechanistic models: Eley-Rideal, Langmuir-Hinshelwood bimolecular adsorption, and Langmuir-Hinshelwood dual site. Among all, Eley-Rideal produced good data fitting and fulfilled the thermodynamic criteria in every case. Combustion kinetics of hexadecane was also studied, since our proposed reactor configuration uses the heat from the exothermic combustion reaction as a driver for the endothermic reforming reaction. It was found that power-law model produced the best fit among all the models and this result was further corroborated using statistical analysis. The kinetic results can be combined with the reactor design model to predict the performance and demonstrate the benefit obtained from simultaneous reforming and combustion.