The effect of catalyst formulation and Rh dispersion on the performance of a CPO fuel processor investigated by operando sampling technique and predictive modelling analysis

The catalytic partial oxidation (CPO) of methane and iso-octane on Rh-coated monoliths is studied in an adiabatic reactor where axial temperature and concentration profiles are collected by a spatially resolved sampling technique. In CH4-CPO, the Rh/MgAl2O4 outperforms the Rh/a-Al2O3 formulation, due to a significant improvement of Rh dispersion. In iso-octane CPO, the beneficial effect of the improved Rh surface is less important due to the intrinsic lower sensitivity of the system. However, a non-negligible impact of Rh dispersion on the extent of hydrocarbon side-products is observed. This factor, together with the lower acidity of the spinel support, contributes to limit the C build-up. Reactor model and kinetic schemes allow to rationalize the measurements and explore the more general effect of Rh specific surface on the key performance indicators of the CPO reformer, that is syngas productivity and hot-spot temperature. Gas-solid diffusion rate makes such indicators strictly fuel-specific.