287379 Transient Isotopic Labeling and in-Situ FT-IR Studies Over Mn/TiO2 Catalysts to Investigate Low Temperature SCR Mechanism of NO with NH3

Monday, October 29, 2012: 9:10 AM
320 (Convention Center )
Thirupathi Boningari1, Padmanabha Reddy Ettireddy2,3, Arpad Somogyvari4 and Panagiotis Smirniotis1, (1)Chemical Engineering Program, School of Energy, Environmental, Biological and Medicinal Engineering, University of Cincinnati, Cincinnati, OH, (2)Tenneco, Inc, Jackson, MI, (3)Chemical Engineering Program, School of Energy, Environmental, Biological and Medicinal Engineering, University of Cincinnati, CINCINNATI, OH, (4)Catalyst Elements, Cummins Emission Solutions, Columbus, IN

In recent years, manganese-based catalysts have attracted much attention because of their unique redox (oxidation-reduction cycle) properties make them useful for a variety of applications. Moreover, Mn-based catalysts have been proven as most active catalysts for the low-temperature selective catalytic reduction (SCR) of NOx. In spite of the rapidly growing commercial applications for the SCR process, the large number of researchers focusing on various aspects of these reactions, there still remains questions about the reaction pathway and the potential intermediate species over these catalysts. For this purpose, the transient isotopic labeling studies were performed under steady state conditions by using 15N (15NO and 15NH3) and 18O (18O2) containing species to investigate the reaction mechanism of the low temperature SCR of NO over Mn/TiO2 with NH3. The results acquired with the time resolution illustrated that the reaction of ammonia with lattice oxygen was practically instantaneous. The formation of labeled N218O, N18O and H218O species is evident through the NH3 contact with catalyst surface lattice oxygen but not direct contact with the gas phase oxygen. Furthermore, the sharp decrease of the unlabeled species 16O16O response on NH3 introduction (at t = fraction of minute) is evident of the instantaneous reaction of surface oxygen species with ammonia. The catalytic performance transient labeling and in-situ FT-IR studies over the Mn/TiO2 material will be discussed in the presentation.

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