A THEORETICAL AND EXPERIMENTAL-STUDY OF CATALYTIC IGNITION IN THE HYDROGEN OXYGEN REACTION ON PLATINUM

The catalytic ignition. i.e., the sudden transition from kinetic control to mass transport control, of nonflammable H2/O2 mixtures in N2 at 1 atm, was in this work investigated experimentally and theoretically. Specifically the dependence of the ignition temperature (where the reaction self-accelerates due to the released chemical power) on the H2/O2 mixing ratio has been measured and simulated by model calculations. The latter take explicitly into account the surface kinetics of the reaction as well as mass and heat transport. The experimentally observed trend of increasing Tign with increasing H2/O2 ratio can, via the simulations, be attributed to a combination of the hydrogen desorption kinetics and a weaker coverage dependence for H2 sticking than for O2 sticking on the surface. The numerical solution of the full model is compared with an approximate analytical expression for Tign. © 1993 Academic Press, Inc.