Akademik Veri Yönetim Sistemi
Tezin Türü: Doktora
Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Kimya Mühendisliği Bölümü, Türkiye
Tezin Onay Tarihi: 2006
Öğrenci: BURCU MİRKELAMOĞLU
Danışman: GÜRKAN KARAKAŞ
Özet:The investigation of CO oxidation with supported noble metal catalysts to develop a fundamental understanding of the nature of the active sites, adsorbate-surface interactions, surface reaction pathways and the role of promoters is of prime importance for development of highly active and selective catalyst formulations for low temperature oxidation of carbon monoxide. Low temperature CO oxidation catalysts find applications in monitoring and elimination of CO in chemical process exhaust gases, in on-board control and diagnostics devices, automobile exhaust gas treatment systems for the development of zero-emission vehicles and, in closed-cycle CO2 lasers for remote sensing. Moreover, the investigation of the interaction of CO with noble metals and noble metals catalyzed oxidation of CO have important outcomes for upstream fuel processing systems and for the development of more CO tolerant anode materials for hydrogen fuel cell. Palladized tin dioxide is a well-known and highly active catalyst for CO oxidation which possesses the potential to satisfy the need for CO oxidation catalysts in the abovementioned areas however, research on this material is concentrated mostly around empirical studies which focus solely on CO sensing applications. This current research is undertaken to investigate both the mechanism of CO oxidation with Pd/SnO2 at the molecular scale and the possibility of promoting the CO activity of this catalyst by the application alkali-metal modifiers. Alkali-metal modified PdO/SnO2 catalysts were characterized by XPS, XRD and SEM and, tested with regard to their oxidation/reduction and CO oxidation behavior by in-situ dynamic methods such as, temperature-programmed reaction/reduction/desorption and impulse techniques. Modification of PdO/SnO2 by alkali-metals, namely Li, Na and K, resulted in catalyst formulations with different surface characteristics and reduction/oxidation behaviors that lead to superior activity in low temperature CO oxidation and selectivity towards CO in the presence of hydrogen. Studies have shown that these catalysts are potential candidates for CO oxidation catalysts in a wide range of areas.