“…While many of these phenomena are well understood, the study of catalytic materials with respect to hydrogen combustion has generally focused on reaction kinetics over known catalytic surfaces [18,19], and does not provide sufficient ignition data to understand potential hazards associated with hydrogen releases. To help develop this data, in our previous work [20] it was shown that in a stagnation configuration, catalytic ignition of hydrogen/air mixtures may occur without external heat addition for equivalence ratios (defined as the ratio of fuel-to-oxidizer ratio and stoichiometric fuel-to-oxidizer ratio) of F 0.2, while for all equivalence ratios and flow strain rates tested, catalytic ignition was observed for surface temperatures of less than 400 K. Post-ignition, the catalyst surface temperature rises to temperatures in excess of 1100 K, well within the 900e1200 K range of reported thermal ignition temperatures from counterflow and stagnation surface experiments [21]. It was additionally observed [20] that catalytic reactions could lead to a gas-phase flame, though the point of this transition was found to be difficult to characterize.…”