Chemistry Department Seminar

Metal-ceria catalysts are promising systems for industrially important reactions such as the water-gas shift reaction for hydrogen production, methane dry reforming (DRM: CH4+CO2 ? 2H2+2CO), and the direct conversion of methane to methanol (DMTM: CH4+ ½ O2 ? CH3OH). However, the complexity of real (powder) catalysts hinders the fundamental understanding of how they work, which is essential for their rational design. Specifically, the role of ceria in the catalytic activity of ceria-based systems is still not fully understood. To unravel it, well-defined ceria-based model cata-lysts consisting of metal nanoparticles deposited on a ceria surface are prepared experimentally or created theoretically and investigated. In this talk, recent results on ceria-supported Ni, Co and Cu model catalysts will be discussed, as examples of catalysts for DRM.1-3 The emphasis is here put on theoretical studies in combination with experiments using ambient pressure X-ray photoelectron spectroscopy, and special attention is given to the effects of ceria as catalyst support. The ability of ceria to stabilize oxidized species (MOx: Co2+ and Ni2+) on the CeO2 surface, by relocalizing electrons on localized f-states, and metal-lic ones (Co0, Ni0) on the reduced CeO2-x support, is essential for CH4 activation ?that occur at tem-peratures as low as 300 K? and its reforming at relatively low temperatures (~700 K). Also, the Ni/ceria system is considered for H2O activation and methanol synthesis from methane and wa-ter.4,5