Direct Decomposition of NO over Ba-Y2O3 Catalyst Prepared by Coprecipitation

The catalytic performance of Ba-Y2O3 prepared by a coprecipitation method for the direct decomposition of NO was investigated. Although Y2O3 catalyzed NO decomposition, its activity was increased by addition of Ba. The maximum NO decomposition activity was achieved on Ba-Y2O3 with 5 wt % Ba loading. XRD measurements revealed the formation of a solid solution of Ba and Y2O3 as well as BaCO3 small particles, when Ba loading was increased up to 5 wt %. From the comparison between the amount of CO2 desorption measured by temperature-programmed desorption of CO2 (CO2-TPD) and the NO decomposition activity of Ba-Y2O3, highly dispersed Ba species, which is initially present as BaCO3 small particles, on the catalyst surface act as catalytically active sites for NO decomposition. On the basis of in situ observation of surface species formed during NO decomposition by Fourier transform infrared (FT-IR) spectroscopy, we proposed that highly dispersed Ba species plays a role for the formation and adsorption of nitrite (NO2-) as reactive species for NO decomposition over Ba-Y2O3 catalyst.