The role of silver species on Ag/Al2O3 catalysts for the selective catalytic oxidation of ammonia to nitrogen |
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| Authors: | Li Zhang Changbin Zhang Hong He |
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| Affiliation: | 1. Dept. of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204-4004, USA;2. Corporate Research and Technology, Cummins Inc., 1900 McKinely Av., Columbus, IN 47201, USA;1. Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China;2. State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China;3. Zhejiang Key Laboratory of Urban Environmental Processes and Pollution Control, Ningbo Urban Environment Observation and Research Station-NUEORS, Chinese Academy of Sciences, Ningbo 315800, China;4. Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, Yunnan, China;1. Chair of Heterogeneous Catalysis and Chemical Technology, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany;2. Center for Automotive Catalytic Systems Aachen, RWTH Aachen University, Schinkelstr. 8, 52062 Aachen, Germany;3. Faculty of Material Science and Ceramics, AGH University of Science and Technology, Mickiewicza 30, 30-059 Kraków, Poland;4. Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland |
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| Abstract: | The role of Ag species on Ag/Al2O3 catalyst for the selective catalytic oxidation (SCO) of NH3 to N2 was studied using 10 wt% Ag/Al2O3 catalysts prepared with impregnation, incipient wetness impregnation and sol–gel methods. The catalyst characterization was preformed using N2 adsorption–desorption, UV/Vis, TEM and XRD. O2-chemisorption and H2–O2 titration were measured to confirm the metal dispersion on the catalyst. The Ag species state and Ag particle size have significant influence on the Ag/Al2O3 activity and N2 selectivity of the SCO of NH3 at low temperature. Ag0 is proposed to be an active species on the H2 pretreated catalyst at low temperature (<140 °C). It is evident that well-dispersed and small particle Ag0 enhances catalytic activity at low temperature, whereas large particle Ag0 is relate to a high N2 selectivity. In contrast, Ag+ could also be the active species at temperatures above 140 °C. |
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