Coating SiO2 Support with TiO2 or ZrO2 and Effects on Structure and CO Oxidation Performance of Pt Catalysts

Catalysts

Mi-Young Kim¹  Jae-Soon Choi¹  Todd J. Toops¹  Eun-Suk Jeong²  Sang-Wook Han²  Viviane Schwartz³ 

[1]Fuels, Engines, and Emissions Research Center, Oak Ridge National Laboratory, Knoxville, TN 37932, USA

[2] E-Mails:

[3]Department of Physics Education and Institute of Fusion Science, Chonbuk National University, Jeonju 561-756, Korea

[4] E-Mails:

[5]Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA

[6] E-Mails:

关键词: platinum;    SiO₂;    TiO₂;    ZrO₂;    surface coating;    sulfur tolerance;    hydrothermal stability;    CO oxidation;    diesel oxidation catalysts;   

DOI  :  10.3390/catal3010088

来源: mdpi

【 摘 要 】

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.

【 授权许可】

CC BY   
© 2013 by the authors; licensee MDPI, Basel, Switzerland.