374792 Controlled Synthesis of Novel Interweaved Titanium Oxide Nanotubes Confined Metal Oxide Catalytic Formulations: Effect of Morphology on Selective Catalytic Reduction (SCR) of NOx By NH3

Monday, November 17, 2014: 9:30 AM
308 (Hilton Atlanta)
Thirupathi Boningari1, Dimitrios Pappas1 and Panagiotis Smirniotis2, (1)Chemical Engineering Program, School of Energy, Environmental, Biological and Medicinal Engineering, University of Cincinnati, Cincinnati, OH, (2)Chemical Engineering, College of Engineering and Applied Science, University of Cincinnati, Cincinnati, OH

The textural properties of various metal oxide confined titania nanotubes and their influence on surface active sites for NH3−SCR were studied. Remarkably, the surface texture and tubular morphology of Me/TNT-H catalysts greatly promoted the NOx conversions and temperature window compared to their nanoparticles. It can be ascribed to the preferentially located active species in the tubular framework. The impregnation of MnOx over TNT-SA catalyst occur bare minimum because of the low specific surface area and low porevolume compared to other titania natotube supports, and this leads to poor deNOx activity and narrow temperature window. Raman and X-ray diffraction patterns indicated that tubular structure in Mn/TNT samples significantly increases the concentration of oxygen vacancies and thus facilitate NO oxidation to NO2. The relative atomic percentage value of Mn4+/Mn3+ characterized by deconvoluted XPS spectra was considerably high for the Mn(0.25)/TNT-H catalyst (Mn4+/Mn3+ = 2.15) whereas, surface Mn3+ species are in equivalence with MnO2 phase in other catalysts (Mn4+/Mn3+ = 0.36-1.34). In H2-TPR, the disappearance of high-temperature reduction peak at 482 oC suggests that the Mn4+ species are dominant in Mn/TNT-H sample compared to Mn/TiO2 nanoparticles. Our Raman results illustrate the redshift of 14 cm-1 from 640 cm-1 (TiO2-Hombikat) to 626 cm-1 in Mn/TNTs-H sample which indicates the formation of a new phase or structural difference. In comparison with the Mn supported on TiO2 (Hombikat) nanoparticles, the Mn species on the developed tubular Mn/TNT-H were less pronounced to coagulate under the reaction temperatures (100-300 oC) and demonstrated an impressive promotion in the deNOx performance and SCR activity window. The intrinsic activity of the prepared catalysts measured under differential reaction conditions and the effect of morphological features will be discussed in the presentation.

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