On the performance of Ag/Al2O3 as a HC-SCR catalyst – influence of silver loading, morphology and nature of the reductant
Journal article, 2013

This study focuses on the performance of Ag/Al2O3 catalysts for hydrocarbon selective catalytic reduction (HC-SCR) of NOx under lean conditions, using complex hydrocarbons as reductants. The aim is to elucidate the correlation towards the silver loading and morphology, with respect to the nature of the reductant. Ag/Al2O3 samples with either 2 or 6 wt% silver loading were prepared, using a sol–gel method including freeze-drying. The catalytic performance of the samples was evaluated by flow reactor experiments, with paraffins, olefins and aromatics of different nature as reductants. The physiochemical properties of the samples were characterized by scanning electron microscopy/energy dispersive X-ray spectroscopy, scanning transmission electron microscopy/high angle annular dark field imaging, X-ray photoelectron spectroscopy and N2-physisorption. The 2 wt% Ag/Al2O3 sample was found to be the most active catalyst in terms of NOx reduction. However, the results from the activity studies revealed that the decisive factor for high activity at low temperatures is not only connected to the silver loading per se. There is also a strong correlation between the silver loading and morphology (i.e. the ratio between low- and high- coordinated silver atoms) and the nature of the hydrocarbon, on the activity for NOx reduction. Calculated reaction rates over the low-coordinated step and high- coordinated terrace sites showed that the morphology of silver has a significant role in the HC-SCR reaction. For applications which include complex hydrocarbons as reductants (e.g. diesel), these issues need to be considered when designing highly active catalysts.

Author

Hannes Kannisto

Competence Centre for Catalysis (KCK)

Chalmers, Chemical and Biological Engineering, Applied Surface Chemistry

Kalle Arve

Åbo Akademi

Torben Pingel

Competence Centre for Catalysis (KCK)

Chalmers, Applied Physics, Eva Olsson Group

Anders Hellman

Chalmers, Applied Physics, Chemical Physics

Competence Centre for Catalysis (KCK)

Hanna Härelind

Competence Centre for Catalysis (KCK)

Chalmers, Chemical and Biological Engineering, Applied Surface Chemistry

Kari Eränen

Åbo Akademi

Eva Olsson

Chalmers, Applied Physics, Eva Olsson Group

Competence Centre for Catalysis (KCK)

Magnus Skoglundh

Chalmers, Chemical and Biological Engineering, Applied Surface Chemistry

Competence Centre for Catalysis (KCK)

Dmitry Yu. Murzin

Åbo Akademi

Catalysis Science and Technology

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

Vol. 3 3 644-653

Driving Forces

Sustainable development

Areas of Advance

Nanoscience and Nanotechnology (2010-2017)

Transport

Energy

Materials Science

Subject Categories

Physical Chemistry

Chemical Process Engineering

Materials Chemistry

DOI

10.1039/c2cy20594g

More information

Latest update

11/5/2018