Analysis of the kinetics for the H₂ + $- \frac{1}{2}$O₂ ⇌ H₂O reaction on a hot Pt surface in the pressure range 0.10–10 Torr

Abstract

The H₂ + $- \frac{1}{2}$O₂ ⇌ H₂O reaction on platinum at 700 and 1300 K has been studied. A stagnation flow geometry was used with a gas mixture of H₂ and O₂ at pressures between 0.10 and 10 Torr. Comparing SHG results with simulations using different reaction parameters, it was concluded that $E_{{\text{H}}_{\text{2}} {\text{O}}}^{\text{f}} \approx 0.7{\text{eV,}}\;E_{{\text{OH}}}^{\text{f}} \approx 0.7{\text{eV}}$, and $E_{{\text{OH}}}^{\text{d}} \approx 2.6{\text{eV}}$. LIF measurements showed an ambiguity in the choice of main water-producing channel. Both hydrogen addition with low sticking coefficients and hydroxyl disproportionation with high sticking coefficients are plausible.