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This paper focuses on the activity for lean NO_x reduction over sol-gel synthesized silver alumina (Ag/Al₂O₃) catalysts, with and without platinum doping, using ethanol (EtOH), EtOH/C₃H₆ and EtOH/gasoline blends as reducing agents. The effect of ethanol concentration, both by varying the hydrocarbon-to-NO_x ratio and by alternating the gasoline concentration in the EtOH/gasoline mixture, is investigated. High activity for NO_x reduction is demonstrated for powder catalysts for EtOH and EtOH/C₃H₆ as well as for monolith coated catalysts (EtOH and EtOH/gasoline). The results show that pure Ag/Al₂O₃ catalysts display higher NO_x reduction and lower light-off temperature as compared to the platinum dopedmore » samples. The 4 wt.% Ag/Al₂O₃ catalyst displays 100% reduction in the range 340–425 °C, with up to 37% selectivity towards NH₃. These results are also supported by DRIFTS (Diffuse reflection infrared Fourier transform spectroscopy) experiments. Finally, the high ammonia formation could, in combination with an NH₃-SCR catalyst, be utilized to construct a NO_x reduction system with lower fuel penalty cf. stand alone HC-SCR. In addition, it would result in an overall decrease in CO₂ emissions.« less