Promotion of surface SO x on the selective catalytic reduction of NO by hydrocarbons over Ag/Al 2O 3

• Published in: Applied surface science Vol. 252; no. 18; pp. 6390 - 6393
• Main Authors: Ouyang, Feng, Zhu, Rong-shu, Sato, Kazuhito, Haneda, Masaaki, Hamada, Hideaki
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2006
• Subjects: Ag/Al 2O 3; Hydrocarbon; NO x reduction; Sulfate; NO x reduction; Hydrocarbon; Sulfate; Ag/Al 2O 3
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2006.01.052

The promotion of sulfur oxides on the selective catalytic reduction (SCR) of NO by hydrocarbons in the presence of a low concentration of sulfur oxides over Ag/Al 2O 3 has been investigated by a flow reaction test and in situ infrared spectroscopy. When the C 3H 6 (or C 10H 22) + NO + O 2 feed-flow reaction was tested, maximum NO reduction was below 30% over fresh Ag/Al 2O 3. After the addition of SO 2 to the feed flow, conversion increased slightly. Conversion increased further after SO 2 was cut-off from the feed flow. This demonstrated that the increase in NO reduction activity of the catalyst was related to SO x adsorbed on the catalyst. SO x adsorbed on the catalytic surface (1375 cm −1) was detected by IR spectroscopy and was stable within the temperature range. NCO species, as an intermediate in NO reduction, on SO x -adsorbed Ag/Al 2O 3 in a C 3H 6 + NO + O 2 feed flow was observed in in situ IR spectra during the elevation of the reaction temperature from 473 to 673 K, while it was only observed at 673 K on fresh Ag/Al 2O 3 under the same experimental conditions. We suggest that SO x in low concentrations depressed the combustion of reductants by contaminating hydrocarbon combustion active sites on the catalyst, resulting in an increase in NO reduction efficiency of the reductants.