In situ DRIFTS study of NO reduction with CH4 over PtCo-ferrierite catalysts

The effect of platinum incorporated into Co-ferrierite catalyst on the selective catalytic reduction of NOx with CH4 was studied by means of in situ DRIFTS technique. NO adsorption on Co- and PtCo-ferrierite catalysts gave dinitrosyl and mononitrosyl species on Co2+ ions. The adsorption of NO+O-2 on Co-ferrierite yielded NO2 (NO2delta+) species and also nitrites and nitrates. Similar species were observed on PtCo-ferrierite, although chemisorbed NO2 was much more stable since it persisted at reaction temperatures as high as 723 K. The spectra of the pre-reduced bimetallic PtCo-ferrierite catalyst exposed to the CH4+NO+O-2 reaction mixture showed bands at 2200-2100 cm(-1), which were similar to results for a Pt-free sample but slightly more intense. In addition, strong bands of nitrate, almost unchanged with temperature, were observed. A very stable Co2+-NO2 intermediate species was developed upon incorporation of Pt into the base Co-ferrierite catalyst.