Theoretical and experimental investigation of water-gas shift reaction over supported copper/iron oxide catalysts

Yalçın, Özgen
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).


Development of Ru0/MO2 (M = Ti, Zr, Hf, Ce) catalysts for electrocatalytic hydrogen production from water splitting
Demir, Elif; Önal, Ahmet Muhtar; Department of Chemistry (2017)
In this study, Ru0/MO2 catalysts were prepared by reduction of ruthenium(III) chloride on different types of metal oxides, which were TiO2, ZrO2, CeO2 and HfO2, then catalysts were loaded on glassy carbon (GC) electrodes at same mass loading level, and used as electrocatalysts in 0.5 M H2SO4 solution for hydrogen evolution reaction (HER). Characterization of prepared catalysts were done by using transmission electron microscopy (TEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD) spectroscopy and X...
Investigation of ruthenium-copper bimetallic catalysts for direct epoxidation of propylene: A DFT study
Kizilkaya, Ali Can; Senkan, Selim; Önal, Işık (2010-09-01)
Propylene epoxidation reactions are carried out on Ru-Cu(1 1 1) and Cu(1 1 1) surfaces with periodic density functional theory (DFT) calculations. Ru-Cu(1 1 1) surface is modeled as Cu(1 1 1) monolayer totally covering the Ru(0 0 0 1) surface underneath, in accordance with the literature. It is shown that the Ru-Cu(1 1 1) surface is ineffective for propylene oxide formation since it has a lower energy barrier (0.48 eV) for the stripping of the allylic hydrogen of propylene and a higher energy barrier (0.92 ...
Quantum chemical simulation of nitric oxide reduction by ammonia (scr reaction) on v2o5 / tio2 catalyst surface
Soyer, Sezen; Önal, Işıl; Department of Chemical Engineering (2005)
The reaction mechanism for the selective catalytic reduction (SCR) of nitric oxide by ammonia on (010) V2O5 surface represented by a V2O9H8 cluster was simulated by density functional theory (DFT) calculations. The computations indicated that SCR reaction consisted of three main parts. In the first part ammonia activation on Brønsted acidic V-OH site as NH4+ species by a nonactivated process takes place. The second part includes the interaction of NO with pre-adsorbed NH4 + species to eventually form nitros...
Theoretical optical spectra of some [2(2)](1,4)-cyclophane fused tetraazaporphyrins
Türker, Burhan Lemi (2002-07-26)
ZINDO/S type semiempirical molecular orbital calculations were carried out on the benzo and [22](1,4)-cyclophane fused tetraazaporphyrins. The phane deck was found to be influential on UV-Vis singlet transitions causing some bathochromic shifts.
Theoretical prediction of bulk glass forming ability (BGFA) of Ti-Cu based multicomponent alloys
SUER, Sila; Mehrabov, Amdulla; Akdeniz, Mahmut Vedat (Elsevier BV, 2009-03-01)
The bulk glass forming ability (BGFA) of Ti-Cu based multicomponent alloys has been evaluated via theoretical modeling and computer simulation studies based on a combination of electronic theory of alloys in the pseudopotential approximation and the statistical thermodynamical theory of liquid alloys The. magnitude of atomic ordering energies, calculated by means of the electronic theory of alloys in the pseudopotential approximation, was subsequently used for calculation of the key thermodynamic parameters...
Citation Formats
Ö. Yalçın, “Theoretical and experimental investigation of water-gas shift reaction over supported copper/iron oxide catalysts,” Ph.D. - Doctoral Program, Middle East Technical University, 2017.