Abstract: The selective catalytic reduction (SCR) of NO with CH₄ was studied in combination of non-thermal plasma and catalysts. Among the series of metal oxides as catalysts, γ-Al₂O₃ exerts the highest activity. At 300 ^oC and the discharge power of 4.5 W, the NO conversion reaches 56.5% in the combination of plasma with γ-Al₂O₃, much higher than that in pure plasma mode (28.9%). At this temperature, no conversion of NO or CH₄ was observed in pure catalytic reaction with γ-Al₂O₃ as the catalyst, indicating a synergistic function between the plasma and the catalyst. As further investigation shows, the catalytic activity has inverse correlation with dielectric constant on the whole. The porous structure and surface acidity of the catalysts obviously promote the plasma-assisted SCR of NO with CH₄.

Key words: methane, nitrogen oxide, selective catalytic reduction, ?-alumina, non-thermal plasma, synergistic effect