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

Wang, Xueting,1991Chalmers tekniska högskola,Chalmers University of Technology (författare)

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.

Chen, Lin,1990Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)clin (författare)
Vennestrøm, Peter (författare)
Janssens, Ton (författare)
Jansson, Jonas,1973Volvo Cars(Swepub:cth)jansson (författare)
Grönbeck, Henrik,1966Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)ghj (författare)
Skoglundh, Magnus,1965Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)skoglund (författare)
Chalmers tekniska högskolaVolvo Cars (creator_code:org_t)

Av författaren/redakt...: Wang, Xueting, 1 ...; Chen, Lin, 1990; Vennestrøm, Pete ...; Janssens, Ton; Jansson, Jonas, ...; Grönbeck, Henrik ...; visa fler...; Skoglundh, Magnu ...; visa färre...

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