In situ DRIFT studies on N2O formation over Cu-functionalized zeolites during ammonia-SCR
Journal article, 2022

The influence of the zeolite framework structure on the formation of N2O during ammonia-SCR of NOx was studied for three different copper-functionalized zeolite samples, namely Cu-SSZ-13 (CHA), Cu-ZSM-5 (MFI), and Cu-BEA (BEA). The evolution of surface species during the SCR reaction at different temperatures was monitored with step-response experiments using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) at different reaction conditions. Also, density functional theory (DFT) calculations were performed to assist the interpretation of the experimental results. The DRIFTS results indicate that NO+ and nitrate species are the main products formed during NO oxidation, and NO appears to adsorb on both Cu-Lewis and Al-Lewis acid sites. The DFT calculations for NO adsorption on the SSZ-13 sample reveal adsorption at Bronsted acid sites with similar adsorption energies but with a slight difference in NO+ stretching vibrations in the DRIFT spectra. Within the standard SCR reaction, in the O-H stretching region, the number of NH3 molecules adsorbed on the Bronsted acid sites is higher for the small-pore size sample compared to the medium- and large-pore zeolites. The obtained DRIFTS results for nitrate species are supported by DFT calculations by simulating the IR spectra of mobile and framework bound nitrate species, which both have a signature at 1604 cm(-1) associated with the O-N bond on NO3-. It is revealed that N2O is produced in a higher amount at lower temperatures for all three samples irrespective of the NO/NO2 ratio. Furthermore, the obtained results from both DRIFTS studies and flow reactor experiments show the higher formation of N2O for the large-pore zeolite compared to the medium- and small-pore zeolite.

Author

Ghodsieh Isapour Toutizad

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry

Aiyong Wang

Chalmers, Chemistry and Chemical Engineering, Chemical Technology

Joonsoo Han

Chalmers, Chemistry and Chemical Engineering, Chemical Technology

Yingxin Feng

Chalmers, Physics, Chemical Physics

Henrik Grönbeck

Chalmers, Physics, Chemical Physics

Derek Creaser

Chalmers, Chemistry and Chemical Engineering, Chemical Technology

Louise Olsson

Chalmers, Chemistry and Chemical Engineering, Chemical Technology

Magnus Skoglundh

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry

Hanna Härelind

Chalmers, Chemistry and Chemical Engineering

Catalysis Science and Technology

2044-4753 (ISSN) 2044-4761 (eISSN)

Vol. In Press

Subject Categories

Inorganic Chemistry

Materials Chemistry

Theoretical Chemistry

DOI

10.1039/d2cy00247g

More information

Latest update

5/23/2022