Reactivity of Cu-based zeolites and oxide in the conversion of NO in the presence or absence of O2

The reactivity of Cu-exchanged zeolites (ZSM-5 and Boralite ) and Cu-loaded oxide (Al2O3, SiO2, TiO2 and ZrO2) for the conversion of NO in the presence or absence of gaseous oxygen is compared. Cu-loaded oxide are active in NO conversion only when oxygen vacancies are created, whereas Cu-ZSM-5 shows a high stable activity, which, however, depends considerably on the NO concn. and formation of sp. active sites. In the presence of O2 a different reaction mechanism occurs and it is shown that O2 can promote the conversion of NO to N2, but at lower reaction temps. and with a lower selectivity than those for the anaerobic decompn. Furthermore, Cu-zeolites showing different anaerobic activity in NO decompn., have comparable behaviors in the aerobic conversion of NO. Cu-ZrO2 and CuO-TiO2 are different from CuO-Al2O3 and CuO-SiO2, and the former show some analogies in the behavior with those of Cu-zeolites. [on SciFinder(R)]