Promotional effect of SO2 on the activity of Ir/SiO2 for NO reduction with CO under oxygen-rich conditions
Affiliation:
1. Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan;2. Department of Materials Science and Technology, Faculty of Engineering, Gifu University, Yanagido 1-1, Gifu 501-1193, Japan;1. Department of Chemical Engineering, Swearingen Engineering Center, University of South Carolina, Columbia, SC 29208, USA;2. Toyota Motor Engineering & Manufacturing North America, Inc, 1555 Woodridge Ave., Ann Arbor, MI 48105, USA;1. Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China;2. Center of Modern Analysis, Nanjing University, Nanjing 210093, China;1. Catalysis Research Center, Hokkaido University, Sapporo 001-0021, Japan;2. Department of Physical and Organic Chemistry, Jo?ef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia;1. School of Ecology and Environment, Inner Mongolia University, China;2. School of Environmental Science & Technology, Dalian University of Technology, China;3. College of Veterinary Medicine, University of Florida, United States
Abstract:
The effect of coexisting SO2 on the activity of silica-supported noble metal catalysts for the selective reduction of NO with CO in the presence of O2 was investigated. Pt/SiO2, Rh/SiO2, and Pd/SiO2 showed little catalytic activity for NO reduction, irrespective of coexisting SO2. Although Ir/SiO2 showed no NO reduction activity in the absence of SO2, the presence of SO2 drastically promoted NO reduction. A comparison of the catalytic performance of Ir/SiO2 and Ir/Al2O3 in the presence of SO2 showed that Ir supported on SiO2 is more active than Ir on Al2O3. SiO2 was found to be a more effective support than Al2O3. The most outstanding feature of the reaction on the Ir/SiO2 catalyst was that the coexistence of SO2 and O2 is essential for NO reduction to occur. The role of coexisting SO2 was considered to be not only to stabilize but also to create Ir0 sites in an oxidizing atmosphere. FT-IR measurements suggested that a cis-type coordinated species of NO and CO on one iridium atom (
