Taking advantage of hysteresis in methane partial oxidation over Pt on honeycomb monolith

A honeycomb monolith with a Pt/γ-Al₂O₃ catalyst has been tested in order to highlight and explain the bifurcation behavior of catalytic methane (partial) oxidation under process conditions, elucidating the light off behavior. With CH₄/O₂=1 (rich mixture) and different heating/cooling policies it has been shown that hysteresis occurs only after complete ignition of the catalyst. The dependence of hysteresis on the feed composition was studied, showing that it disappears with lean mixtures, has its maximum for slightly richer than stoichiometric mixtures and then decreases with much richer composition. At the same time, the ignition temperature lowers with increasing CH₄/O₂ ratio. Finally, we suggest a procedure to decrease the ignition temperature by taking advantage of the hysteretic behavior, gradually tuning the feed composition, with the only limit given by the thermal insulation capabilities.