Design of a novel bifunctional catalyst IrFe/Al2O3 for preferential CO oxidation

✍ Scribed by Wansheng Zhang; Aiqin Wang; Lin Li; Xiaodong Wang; Tao Zhang

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 784 KB
• Volume: 131
• Category: Article
• ISSN: 0920-5861
• DOI: 10.1016/j.cattod.2007.10.058

✦ Synopsis

In this study, a novel bifunctional catalyst IrFe/Al 2 O 3 , which is very active and selective for preferential oxidation of CO under H 2 -rich atmosphere, has been developed. When the molar ratio of Fe/Ir was 5/1, the IrFe/Al 2 O 3 catalyst performed best, with CO conversion of 68% and oxygen selectivity towards CO 2 formation of 86.8% attained at 100 8C. It has also been found that the impregnation sequence of Ir and Fe species on the Al 2 O 3 support had a remarkable effect on the catalytic performance; the activity decreased following the order of IrFe/Al 2 O 3 > co-IrFe/ Al 2 O 3 > FeIr/Al 2 O 3 . The three catalysts were characterized by XRD, H 2 -TPR, FT-IR and microcalorimetry. The results demonstrated that when Ir was supported on the pre-formed Fe/Al 2 O 3 , the resulting structure (IrFe/Al 2 O 3 ) allowed more metallic Ir sites exposed on the surface and accessible for CO adsorption, while did not interfere with the O 2 activation on the FeO x species. Thus, a bifunctional catalytic mechanism has been proposed where CO adsorbed on Ir sites and O 2 adsorbed on FeO x sites; the reaction may take place at the interface of Ir and FeO x or via a spill-over process.