Self-sustained catalytic combustion of carbon monoxide ignited by dielectric barrier discharge

This paper presents the results of a study of self-sustained catalytic combustion of CO ignited by dielectric barrier discharge (DBD) using Ce0.5Zr0.5Oy/TiO2 (CeZr/Ti), CuZr0.25Oy/TiO2 (CuZr/Ti), and CuCe0.75Zr0.25Oy/TiO2 (CuCeZr/Ti) catalysts. DBD excites and dissociates some of the reactant molecules in the gas phase. These are more easily adsorbed on the catalyst surface than are ground-state species, therefore induction begins at a lower background temperature than in thermal catalysis. CO is adsorbed on copper sites, therefore CeZr/Ti is inactive in CO ignition, but CuZr/Ti and CuCeZr/Ti achieve DBD ignition at 34 and 44 s, respectively, at a specific energy density (SED) of 1500 J/L. CO catalytic ignition by DBD involves two steps. The induction process is dominated by plasma catalysis. At the same SEDs, induction with CuCeZr/Ti begins earlier than those with CuZr/Ti, in good agreement with the reducibilities and oxygen-transfer properties of these catalysts. The ignition process is governed by thermal catalysis because the enhancement of external diffusion induced by increasing the temperature improves the reaction rate. CuZr/Ti provided more CO adsorption sites than did CuCeZr/Ti, contributing to shortening of the ignition delay.