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Coating SiO2 Support with TiO2 or ZrO2 and Effects on Structure and CO Oxidation Performance of Pt Catalysts
Fuels, Engines, and Emissions Research Center, Oak Ridge National Laboratory, Knoxville, TN 37932, USA
Department of Physics Education and Institute of Fusion Science, Chonbuk National University, Jeonju 561-756, Korea
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
* Author to whom correspondence should be addressed.
Received: 10 November 2012; in revised form: 13 November 2012 / Accepted: 29 January 2013 / Published: 6 February 2013
Abstract: In this work, we studied how TiO2 and ZrO2 coatings enhance the CO oxidation performance of SiO2-supported Pt catalysts under conditions relevant to automotive emissions control. SiO2 was coated with metal oxides TiO2 or ZrO2 by sol-gel method and the subsequent Pt loading was done by incipient wetness method. The prepared catalysts Pt/TiO2-SiO2 and Pt/ZrO2-SiO2 were compared with Pt/SiO2 and Pt/Al2O3 in fresh, sulfated, and hydrothermally aged states. The structure of the catalysts was characterized with BET, XRD, TEM, EDS, EXAFS, XANES, TPD and TPR to help interpret the CO oxidation performance. Higher dispersion, stability, and oxidation state of Pt were achieved on TiO2-SiO2 and ZrO2-SiO2 supports due to stronger metal-support interaction leading to superior CO oxidation performance compared to Pt/SiO2 and Pt/Al2O3. TiO2 and ZrO2 coatings introduced surface acidity but negligible basicity, which is a likely reason for the weak and low adsorption of SO2. The results suggest that the sol-gel coating of SiO2 with metal oxides could be an attractive strategy for designing automotive oxidation catalysts with enhanced performance such as low-temperature activity, sulfur tolerance, and hydrothermal stability.
Keywords: platinum; SiO2; TiO2; ZrO2; surface coating; sulfur tolerance; hydrothermal stability; CO oxidation; diesel oxidation catalysts
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Kim, M.-Y.; Choi, J.-S.; Toops, T.J.; Jeong, E.-S.; Han, S.-W.; Schwartz, V.; Chen, J. Coating SiO2 Support with TiO2 or ZrO2 and Effects on Structure and CO Oxidation Performance of Pt Catalysts. Catalysts 2013, 3, 88-103.
Kim M-Y, Choi J-S, Toops TJ, Jeong E-S, Han S-W, Schwartz V, Chen J. Coating SiO2 Support with TiO2 or ZrO2 and Effects on Structure and CO Oxidation Performance of Pt Catalysts. Catalysts. 2013; 3(1):88-103.
Kim, Mi-Young; Choi, Jae-Soon; Toops, Todd J.; Jeong, Eun-Suk; Han, Sang-Wook; Schwartz, Viviane; Chen, Jihua. 2013. "Coating SiO2 Support with TiO2 or ZrO2 and Effects on Structure and CO Oxidation Performance of Pt Catalysts." Catalysts 3, no. 1: 88-103.