Abstract
The ignition behavior in the oxidation of four simple alkanes (methane,
ethane, propane and isobutane) with air on a platinum-foil catalyst,
as well as that of ethane/air mixtures on four noble-metal foil catalysts
(Pt, Pd, Rh, and Ir) was studied at atmospheric pressure over the
entire range of fuel-to-air ratios. While, Pd showed the widest range
of surface flammability, ignition temperatures for ethane/air mixtures
were lowest on Pt. Both, Rh and Ir deactivated rapidly under fuel-lean
conditions and ignited considerably higher than Pd and Pt. The surface
ignition temperatures were found to correlate well with the C-H bond
energy of the hydrocarbon and the metal-oxygen bond energy of the
noble metal. A very simple analytical model was able to reproduce
the dependence of surface ignition temperatures on fuel-to-air ratios,
yielding apparent activation energies for the surface reactions and
indicating an oxygen-covered surface before catalytic ignition due
to strong site competition between the hydrocarbon and oxygen on
the catalyst surface.
Users
Please
log in to take part in the discussion (add own reviews or comments).