Fig. 3. Time-resolved response of several features present in Fig. 2 during the 15–18 cycles of the NO concentration modulation experiment. (a) NO pulse sequence, (b) out-gas NH3 integral response (online IR detected), (c) [Cu2+(OH–)]+ integral, (d) 1436 cm–1 and (e) 1258 cm–1 bands due to the presence of Cu–N( O)–NH2 species, (f) response of the band at 3605 cm–1 (Brønsted acid site). Close-up of regions in the phase-resolved spectra of Fig. 2, (g) 3800–3300 cm–1 region containing the Brønsted acid site (zeolite OH) and the [Cu2+(OH–)]+ stretches, (h) 1650–1200 cm–1 region relevant for NH3 coordinated Cu and zeolite.
