EFFECT OF OXYGEN VACANCY ON CO-NO-O-2 REACTION OVER YTTRIA-STABILIZEDZIRCONIA-SUPPORTED COPPER-OXIDE CATALYST

The effect of oxygen vacancy on the enhancement of activity of CO-NO-O -2 reaction over yttria-stabilized zirconia (YSZ)-supported CuO cataly st was investigated in the present study. The catalysts were prepared by the impregnation method, and their characteristics were studied by temperature-programmed reduction. The catalyst was placed in a flow re actor for performing the temperature-programmed reaction, and the effl uent gas was analyzed by an on-line NOx analyzer, consisting of a chem iluminescence unit and two gas chromatographs in series. The present r esults indicate that copper oxide supported by YSZ exhibits a higher c atalytic activity than that supported by alpha-Al2O3, for the CO-NO-O- 2 reaction. The enhanced activity is inferred to result from the forma tion of interfacial Cu2O and the oxygen-ion transfer. Additionally, th e probable effect of oxygen vacancy in promoting the CO-O-2 or CO-NO2 reaction has been elucidated by a mechanism involving oxygen-ion trans fer via surface oxygen vacancies of YSZ, which are located at the inte rface between CuO and YSZ. It was found that the CuO/YSZ catalyst is a promising substitute for the conventional Rh/alumina catalyst.