MnO{sub x}-CeO{sub 2} mixed oxides prepared by co-precipitation for selective catalytic reduction of NO with NH{sub 3} at low temperatures Qi, Gongshin; Yang, Ralph T [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109-2136 (United States)]; Chang, Ramsay [Air Pollution Control, Power Generation, Electric Power Research Institute, Palo Alto, CA 94304-1395 (United States)] 54 ENVIRONMENTAL SCIENCES; MANGANESE OXIDES; CERIUM OXIDES; COPRECIPITATION; SELECTIVE CATALYTIC REDUCTION; NITRIC OXIDE; AMMONIA; CATALYSTS; NITROUS OXIDE A series of manganese-cerium oxide catalysts were prepared by co-precipitation method and used for low temperature selective catalytic reduction (SCR) of NO{sub x} with ammonia in the presence of excess O{sub 2}. These catalysts were characterized by X-ray diffraction (XRD), surface area measurement and FTIR. The experimental results showed that the best Mn-Ce mixed-oxide catalyst yielded 95% NO conversion at 150C at a space velocity of 42,000h{sup -1}. As the manganese content was increased from 0 to 40% (i.e. the molar ratio of Mn/(Mn+Ce)), NO conversion increased significantly, but decreased at higher manganese contents. The most active catalyst was obtained with a molar Mn/(Mn+Ce) ratio of 0.4. Only N{sub 2} rather than N{sub 2}O was found in the product when the temperature was below 150C. At higher temperatures, trace amounts of N{sub 2}O were detected. A mechanistic pathway for this reaction was proposed based on earlier findings and FTIR results obtained in this work. The initial step was the adsorption of NH{sub 3} on Lewis acid sites of catalyst, followed by reaction with nitrite species to produce N{sub 2} and H{sub 2}O. Possible intermediates are proposed and all the intermediates could transform into NH{sub 2}NO, which could further react to produce N{sub 2} and H{sub 2}O. Netherlands 2004-07-30 English Journal Article Journal Name: Applied Catalysis. B, Environmental; Journal Volume: 51; Journal Issue: 2; Other Information: PBD: 30 Jul 2004 Medium: X; Size: page(s) 93-106 https://doi.org/10.1016/j.apcatb.2004.01.023 [] 2 51 Journal ID: ISSN 0926-3373; ACBEE3; TRN: NL04E1467 ECN 2010-12-31 20502446