Akademik Veri Yönetim Sistemi
Tezin Türü: Doktora
Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Bilimleri Enstitüsü, Fen Bilimleri Enstitüsü, Türkiye
Tezin Onay Tarihi: 2017
Öğrenci: ÖZGEN YALÇIN
Danışman: IŞIK ÖNAL
Özet:Density functional theory calculations were carried out to investigate the role of the chromium and copper, which were demonstrated to act as textural and catalytic promoters, respectively, for the Fe3O4-Cr2O3-CuO catalyst system by in situ experimental studies at the atomic scale. There is a minor effect of Cr on the dissociative adsorption of H2O, but no effect on CO adsorption on the Feoct2 termination of Fe3O4 (111) surface indicating that Cr does not act as a chemical promoter. Copper promotion of the Feoct2 terminated structure with a supported Cu4 cluster facilitates CO adsorption at the new active sites present at the copper-iron oxide interface. Zirconia-, niobia-, ceria-, and alumina-promoted supported copper/iron oxide catalysts were synthesized and investigated as the Cr-free iron oxide-based catalysts. The characterization studies (ex situ XRD, in situ Raman spectroscopy, High-Sensitivity Low Energy Ion Scattering (LEIS), CO-TPR and flow BET surface area) revealed the interplay between the different components of this dynamic catalyst system. The promoted catalysts were found to have significantly greater thermostability than the unpromoted iron oxide catalyst. The promoted catalysts without copper did not perform better than the unpromoted iron oxide catalyst for the WGS reaction. Al promoter provides better thermostability and higher activity. Desired Cr-free catalyst is the combination of BET stability of Al promoter with redox activity of Ce promoter. This research study combines theoretical and experimental investigations under the partnership between the Department of Chemical Engineering of Middle East Technical University and Department of Chemical & Biomolecular Engineering of Lehigh University (USA).