Direct measurement of enthalpy and entropy changes in NH3 promoted O2 activation over Cu−CHA at low temperature
Journal article, 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

Author

Xueting Wang

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Polymer Technology

Competence Centre for Catalysis (KCK)

Lin Chen

Competence Centre for Catalysis (KCK)

Chalmers, Physics, Chemical Physics

Peter Vennestrøm

Umicore Denmark ApS

Ton Janssens

Umicore Denmark ApS

Jonas Jansson

Volvo Cars

Henrik Grönbeck

Competence Centre for Catalysis (KCK)

Chalmers, Physics, Chemical Physics

Magnus Skoglundh

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Polymer Technology

Competence Centre for Catalysis (KCK)

ChemCatChem

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

Vol. 13 11 2577-2582

Novel high-silica small-pore zeolite catalysts for direct partial oxidation of methane to methanol

Swedish Research Council (VR) (2017-04811), 2018-01-01 -- 2021-12-31.

Subject Categories

Inorganic Chemistry

Atom and Molecular Physics and Optics

Other Chemistry Topics

DOI

10.1002/cctc.202100253

More information

Latest update

8/17/2021