Kinetic Interactions between H₂ and CO in Catalytic Oxidation over PdO

Kinetic interactions between H ₂ and CO over PdO, a widely used catalyst in combustion systems, were studied experimentally and numerically. Global reaction parameters of H ₂ and CO oxidation over PdO were extracted from wire microcalorimetry experiments at atmospheric pressure in the temperature range 380-800 K, based on which a full catalytic reaction mechanism was developed. Comparison of ignition temperatures and heat release rates of different H ₂ /CO blends along with density functional theory (DFT) simulations revealed complex physicochemical coupling of the H ₂ and CO catalytic oxidation pathways. The coupling evolves from an inhibiting effect of one fuel component onto the other due to their competition for surface adsorption sites and a direct repelling mechanism between the co-adsorbed H(s) and CO(s), to a promoting effect at sufficiently high temperatures caused by alleviated O(s) surface blocking. Implications of the H ₂ -CO kinetic coupling to the operation of practical power generation systems are outlined.