Role of hydrogen formation and silver phase for methanol-SCR over silver/alumina

• Formation of H2 during selective catalytic reduction with methanol over Ag/Al2O3.
• Reduction of silver when Ag/Al2O3 is active for lean NOx reduction with methanol.
• H2 formation suggested to explain low-temperature NOx reduction with oxygenates.

Formation of reaction products over silver/alumina during lean NOx reduction with methanol was studied, with and without addition of hydrogen to the feed. The silver phase in silver/alumina was analyzed by UV–vis spectroscopy in order to elucidate the influence of silver loading and different gas environments. Formation of molecular hydrogen and reduction of supported silver species were observed during selective catalytic reduction (SCR) with methanol, without hydrogen in the feed. This availability of hydrogen and the reduction of silver are suggested to contribute to the high low-temperature activity connected to oxygenates (like alcohols) as reducing agents for NOx.

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