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The potential of silver on alumina (Ag/Al 2 O 3 ) catalyst for the oxidation of carbon particles in simulated lean combustion gas was explored. At low temperatures in the presence of NO x , oxygen, and water, the silver of the catalyst is transformed into silver nitrate. On heating, finely dispersed silver metal is formed that catalyzes the oxidation of NO into NO 2 . The carbon oxidation rates in loose mixtures of carbon black and nitrated Ag/Al 2 O 3 catalyst were determined gravimetrically using a magnetic suspension balance and gas mixture comprising nitric oxide, oxygen, and water. The temperature for achieving carbon oxidation was lower with nitrated Ag/Al 2 O 3 than with Pt/Al 2 O 3 . The finely dispersed metallic state of the silver required for efficient NO oxidation can be regenerated in cycles involving cooling and heating in the presence of NO x . |
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