Interaction of NH3 with Cu-SSZ-13 catalyst: a complementary FTIR, XANES and XES study

In the typical NH3-SCR temperature range (100-500 °C), ammonia is one of the main adsorbed species on acidic sites of Cu-SSZ-13 catalyst. Therefore the study of adsorbed ammonia at high temperature is a key step for the understanding of its role in the NH3-SCR catalytic cycle. We employed different spectroscopic techniques in order to investigate the nature of the different complexes occurring upon NH3 interaction. In particular, FTIR spectroscopy revealed the formation of different NH3 species, i.e. (i) NH3 bounded to copper centers, (ii) NH3 bounded to Brønsted sites, and (iii) NH4+ nNH3 associations. XANES and XES spectroscopy allowed us to get an insight on the geometry and electronic structure of Cu canters upon NH3 adsorption, revealing for the first time in Cu-SSZ-13 the presence of linear Cu+ species in Ofw-Cu-NH3 and/or H3N-Cu-NH3 configuration.