Detection of key transient Cu intermediates in SSZ-13 during NH-SCR deNO by modulation excitation IR spectroscopy.

The small pore zeolite Cu-SSZ-13 is an efficient material for the standard selective catalytic reduction of nitrogen oxides (NO ) by ammonia (NH). In this work, Cu-SSZ-13 has been studied at 250 °C under high conversion using a modulation excitation approach and analysed with phase sensitive detection (PSD). While the complementary X-ray absorption near edge structure (XANES) spectroscopy measurements showed that the experiments were performed under cyclic Cu/Cu redox, Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) experiments provide spectroscopic evidence for previously postulated intermediates Cu-N([double bond, length as m-dash]O)-NH and Cu-NO in the NH-SCR deNO mechanism and for the role of [Cu(OH)]. These results therefore help in building towards a more comprehensive understanding of the reaction mechanism which to date has only been postulated .