Detection of key transient Cu intermediates in SSZ-13 during NH3-SCR deNO x by modulation excitation IR spectroscopy

Alex G Greenaway; Adrian Marberger; Adam Thetford; Inés Lezcano-González; Miren Agote-Arán; Maarten Nachtegaal; Davide Ferri; Oliver Kröcher; C Richard A Catlow; Andrew M Beale

doi:10.1039/c9sc04905c

Detection of key transient Cu intermediates in SSZ-13 during NH₃-SCR deNO _x by modulation excitation IR spectroscopy

Chem Sci. 2019 Nov 18;11(2):447-455. doi: 10.1039/c9sc04905c. eCollection 2020 Jan 14.

Authors

Alex G Greenaway^{1

2}, Adrian Marberger³, Adam Thetford^{1

2}, Inés Lezcano-González^{1

2}, Miren Agote-Arán^{1

2}, Maarten Nachtegaal³, Davide Ferri³, Oliver Kröcher³, C Richard A Catlow^{1

2

4}, Andrew M Beale^{1

2}

Affiliations

¹ UK Catalysis Hub , Research Complex at Harwell , Rutherford Appleton Laboratory , Didcot OX11 0FA , UK . Email: andrew.beale@ucl.ac.uk.
² Department of Chemistry , 20 Gordon Street , London , WC1H 0AJ , UK.
³ Paul Scherrer Institut , 5232 Villigen , Switzerland.
⁴ Cardiff Catalysis Institute , School of Chemistry , Cardiff University , Main Building, Park Place , Cardiff , CF10 3AT , UK.

Abstract

The small pore zeolite Cu-SSZ-13 is an efficient material for the standard selective catalytic reduction of nitrogen oxides (NO _x ) by ammonia (NH₃). 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⁺/Cu²⁺ 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)-NH₂ and Cu-NO₃ in the NH₃-SCR deNO _x mechanism and for the role of [Cu²⁺(OH^-)]⁺. These results therefore help in building towards a more comprehensive understanding of the reaction mechanism which to date has only been postulated in silico.