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. 3 3 3 2 3 3 2 2 3 3 2 3 3 + + + + + + +

NH -SCR 3

zeolites

oxygen activation

adsorption

Cu-chabazite

Författare

Xueting Wang

Chalmers, Kemi och kemiteknik, Tillämpad kemi, Polymerteknologi

Kompetenscentrum katalys (KCK)

Lin Chen

Chalmers, Fysik, Kemisk fysik

Kompetenscentrum katalys (KCK)

Peter Vennestrøm

Umicore Denmark ApS

Ton Janssens

Umicore Denmark ApS

Jonas Jansson

Volvo Cars

Henrik Grönbeck

Kompetenscentrum katalys (KCK)

Chalmers, Fysik, Kemisk fysik

Magnus Skoglundh

Kompetenscentrum katalys (KCK)

Chalmers, Kemi och kemiteknik, Tillämpad kemi, Polymerteknologi

ChemCatChem

1867-3880 (ISSN) 1867-3899 (eISSN)

Vol. In Press

Nya småporiga zeolitkatalysatorer med högt kiselinnehåll för direkt partiell oxidation av metan till metanol

Vetenskapsrådet (VR), 2018-01-01 -- 2021-12-31.

Ämneskategorier

Oorganisk kemi

Atom- och molekylfysik och optik

Annan kemi

DOI

10.1002/cctc.202100253

Mer information

Senast uppdaterat

2021-05-06