Direct measurement of enthalpy and entropy changes in NH3 promoted O2 activation over Cu−CHA at low temperature
Artikel i vetenskaplig tidskrift, 2021
Oxygen activation is a key step in the selective catalytic reduction of nitrogen oxides with ammonia (NH -SCR) over Cu-chabazite. We present direct measurements of oxygen adsorption at low temperatures over [NH −Cu−NH ] complexes and framework-bound Cu species in Cu-chabazite with Si/Al=14 using isothermal microcalorimetry combined with mass spectrometry. The enthalpy change for O adsorption over [NH −Cu−NH ] complexes at 200 °C is determined to be −79 kJ/mol. By fitting a Langmuir isotherm, the corresponding entropy change is determined to be −142 J/(mol*K) at 10 % O . The results show that O adsorption at low temperatures over [NH −Cu−NH ] complexes is more facile than on framework-bound Cu species. The experimental results are in agreement with density functional theory calculations showing a lower barrier for O activation over the [NH −Cu−NH ] complexes as compared to the framework-bound Cu species.
zeolites
adsorption
oxygen activation
NH -SCR 3
Cu-chabazite
Författare
Xueting Wang
Chalmers, Kemi och kemiteknik, Tillämpad kemi
Kompetenscentrum katalys
Lin Chen
Kompetenscentrum katalys
Chalmers, Fysik, Kemisk fysik
Peter Vennestrøm
Umicore Denmark ApS
Ton Janssens
Umicore Denmark ApS
Jonas Jansson
Volvo Cars
Henrik Grönbeck
Kompetenscentrum katalys
Chalmers, Fysik, Kemisk fysik
Magnus Skoglundh
Chalmers, Kemi och kemiteknik, Tillämpad kemi
Kompetenscentrum katalys
ChemCatChem
1867-3880 (ISSN) 1867-3899 (eISSN)
Vol. 13 11 2577-2582Nya småporiga zeolitkatalysatorer med högt kiselinnehåll för direkt partiell oxidation av metan till metanol
Vetenskapsrådet (VR) (2017-04811), 2018-01-01 -- 2021-12-31.
Ämneskategorier
Oorganisk kemi
Atom- och molekylfysik och optik
Annan kemi
DOI
10.1002/cctc.202100253