Oxidative reforming (OR) of hydrocarbon is a combination of exothermic (combustion) and endothermic (reforming) reactions and, hence, it is more advantageous for start-up and transient performance than conventional steam reforming (SR). Due to the characteristic, OR is expected to be the preferred approach to produce hydrogen locally in hydrogen filling stations, and for on-site reformers for domestic fuel cells, for which start-up and shutdown is frequently repeated. Multiple criteria have been deemed crucial for the efficient start-up of the reformer including start-up time, overall energy efficiency and catalyst stability. The most critical parameter, however, is related to the catalytic autoignition temperature, which occurs normally above 473K with noble metal catalysts.
Here, we describe a new step up approach that generates the heat internally without the necessity of a specialized start up procedure. When the n-C₄H₁₀/O₂/Ar/N₂ mixture was fed at room temperature on Rh/CeO₂ reduced at 1073 K, the H₂ production rate increased drastically (30.4 L h^-1 g^-1) after 0.2 minute time on stream and reached the maximum and stable value (38.7 L h^-1 g^-1) within several minutes. Power of the furnace was switched off during the experiment. Thus, at that time, the heat was fully balanced among exothermic and endothermic reactions including external heat losses. It has been revealed that the auto ignition is enabled by the heat produced by spontaneous oxidation of the catalytic support.