Effect of heat recirculation on the self-sustained catalytic combustion of propane/air mixtures in a quartz reactor

The self-sustained catalytic combustion of propane is experimentally studied in a two-pass, quartz heat-recirculation reactor (HRR) and compared to that in a no (heat) recirculation reactor (NRR). Structured monolithic reactors with Pt/γ-Al2O3, LaMnO3/γ-Al2O3, and Pt doped perovskite catalysts have been compared in the HRR and NRR configurations. Heat recirculation enhances combustion stability, by widening the operating window of self-sustained operation, and changes the mode of stability loss from blowout to extinction. It is found that thermal shields (upstream and downstream of the monolith) play no role in the stability of a HRR but increase the stability of a NRR. The stability of a HRR follows this trend: Pt/γ-Al2O3 > doped perovskite > LaMnO3/γ-Al2O3. Finally, a higher cell density monolith enlarges the operating window of self-sustained combustion, and allows further increase of the power density of the process.