Fig. 10. DRIFTS spectra of the NOx adsorption of the CeaTabOx series catalysts at 100 °C (a). Deconvoluted results of bands attributed to nitrite and nitrate Mutant IDH1-IN-1 (b). Correlation between amounts of relevant nitrite and nitrate species and the CeaTabOx series catalysts (c).Figure optionsDownload full-size imageDownload as PowerPoint slide
Fig. 11 shows the DRIFTS spectra of NO + O2 on Ce1Ta1Ox in the temperature range of 100–350 °C. The intensities of the bands assigned to monodentate nitrite, monodentate nitrate, bridging nitrate and adsorbed NO2 content decrease with increasing temperature, whereas the intensity of the band ascribed to bidentate nitrate exhibits a slight increase in the range of 100–200 °C and then a significant decrease at 200 °C and higher temperatures. These findings indicate that the variation from bridging nitrate into a bidentate nitrate happened at low temperatures. Meanwhile, it can be found that the bridging and bidentate nitrates remain adsorbed on the catalyst in a relative thermal stability form until approximately 350 °C. In contrast, monodentate nitrite and monodentate nitrate can hardly be observed at high temperatures (≥250 °C).