Surface kinetics for catalytic combustion of hydrogen-air mixtures on platinum at atmospheric pressure in stagnation flows

Heterogeneous–homogeneous interactions in catalytic microchannel reactors

“…Therefore, the temperature increase upon ignition in the previous studies might lead to a strong increase in the backward reaction OH(S) ϩ PT(S) f O(S) ϩ H(S) (reaction 13 in Table 3) because this reaction has a particularly large activation energy. This could open a competition for OH(S) between this backward reaction and water formation by reaction 16, thus introducing sensitivity toward the latter reaction and reconciling our findings with the results from Ikeda et al 38 Another difference from Rinnemo et al 37 is the high nitrogen dilution and low-temperature range (ϳ300 -500 K) of their investigation. Nevertheless, their observation that the Pt surface is essentially H-poisoned up to the ignition point agrees qualitatively well with the surface coverages ob- [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]…”

“…It should be mentioned that this result is in disagreement with previous studies, which identified adsorption and desorption of hydrogen on the Pt surface, 37 or reaction 16, that is, water formation from OH(S) and H(S) on the catalyst surface, 38 respectively, as rate-determining steps. We cannot completely resolve this discrepancy between our findings and the findings of these studies (nor the discrepancy between their findings), but a significant difference between these previous studies and our present study is the fact that we restricted our investigation to isothermal surface conditions.…”

Extinction limits of nonadiabatic, catalyst-assisted flames in stagnation-point flow

“…In addition to previous experimental investigations (cf. Law et al [4]; Ikeda et al [5]), this geometry is also suggested by more recent experiments (Gardner et al [6]) on small-volume combustors. In the latter application, such a combustor (nominally 2500µ × 2500µ × 400µ) is fed by an inlet tube that blows against a catalytic surface (platinum mounted on a titanium/silicon wafer) and is vented by one or more outlet ports on either the opposite face (shortest dimension) or sides.…”

Modelling CO poisoning and O2 bleeding in a PEM fuel cell anode

“…However, oxygen can also react with adsorbed hydrogen. The heterogeneous oxidation of H 2 by O 2 on platinum has many intermediate reactions (Ikeda et al, 1995), but it can also be approximated by a Langmuir-Hinshelwood mechanism (Norton, 1982).…”