Show/Hide Menu
Hide/Show Apps
Logout
Türkçe
Türkçe
Search
Search
Login
Login
OpenMETU
OpenMETU
About
About
Open Science Policy
Open Science Policy
Open Access Guideline
Open Access Guideline
Postgraduate Thesis Guideline
Postgraduate Thesis Guideline
Communities & Collections
Communities & Collections
Help
Help
Frequently Asked Questions
Frequently Asked Questions
Guides
Guides
Thesis submission
Thesis submission
MS without thesis term project submission
MS without thesis term project submission
Publication submission with DOI
Publication submission with DOI
Publication submission
Publication submission
Supporting Information
Supporting Information
General Information
General Information
Copyright, Embargo and License
Copyright, Embargo and License
Contact us
Contact us
Oxygen adsorption on Pt/TiO2 catalysts
Date
2003-09-30
Author
Üner, Deniz
Ozen, I
Uner, M
Metadata
Show full item record
This work is licensed under a
Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License
.
Item Usage Stats
170
views
0
downloads
Cite This
Oxygen adsorption overPt/TiO2 surfaces were investigated as a function of metal loading. Oxygen adsorption over pure TiO2 was molecular at all pressure ranges investigated. On the other hand, differential heats of adsorption measured by adsorption calorimetry indicated that oxygen adsorption was dissociative over Pt/TiO2 surfaces until the Pt surface was saturated with oxygen. The saturation coverage of atomic oxygen on Pt was determined as approximately one from adsorption calorimetry. The initial heat of oxygen adsorption was determined as similar to375 kJ/mol over 0.5 wt.% Pt/TiO2. The differential heats of oxygen adsorption at coverages less than one monolayer of Pt surface was similar to200 kJ/mol consistent with the oxygen adsorption heats over Pt single crystals reported in the literature. As the pressure increased after the saturation of Pt surface, oxygen adsorption continued in a manner similar to oxygen adsorption over pure TiO2. Isosteric heats of oxygen adsorption over pure and Pt/TiO2 samples at coverages >5 mumol/g catalyst were determined to be around 10 kJ/mol. The amounts of oxygen adsorption over Pt/TiO2 surfaces depended strongly on the pretreatment conditions. Most favorable oxygen adsorption was observed over calcined/reduced samples.
Subject Keywords
Process Chemistry and Technology
,
Catalysis
URI
https://hdl.handle.net/11511/43464
Journal
APPLIED CATALYSIS A-GENERAL
DOI
https://doi.org/10.1016/s0926-860x(03)00317-x
Collections
Department of Chemical Engineering, Article
Suggestions
OpenMETU
Core
Oxygen Mobility in Pre-Reduced Nano- and Macro-Ceria with Co Loading: An AP-XPS, In-Situ DRIFTS and TPR Study
Sohn, Hyuntae; Çelik, Gökhan; Gunduz, Seval; Dogu, Doruk; Zhang, Shiran; Shan, Junjun; Tao, Franklin Feng; Ozkan, Umit S. (Springer Science and Business Media LLC, 2017-01-01)
The size effect of ceria nanoparticles on surface oxygen mobility and formation of surface oxygen vacancies in ethanol steam reforming was investigated. Higher concentration of Ce3+ surface sites of the ceria nano-particles (~4 nm, NP) was observed compared to the micro-particles (~120 nm, MP). Similarly, studies using ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) exhibited higher intensity of O1s assigned to the hydroxyl group bonding to Ce3+ and significantly lower intensity for lattice oxyge...
Exceptionally thermally stable, hydrocarbon soluble Ziegler-type Ir(0)(n) nanoparticle catalysts made from [Ir(1,5-COD)(mu-O2C8H15)](2) plus AlEt3: Tests of key hypotheses for their unusual stabilization
Hamdemir, Isil K.; Özkar, Saim; Finke, Richard G. (Elsevier BV, 2013-11-01)
In recent work we showed that Ziegler-type nanoparticles made from [Ir(1,5-COD)(mu-O2C8H15)](2) plus AlEt3 are an unusually thermally stable (>= 30 min at 200 degrees C), hydrocarbon-solvent soluble, high catalytic activity nanoparticle catalyst (I.K. Hamdemir, S. Ozkar, K.-H. Yih, J.E. Mondloch, R.G. Finke, ACS Catal. 2 (2012) 632-641). As such, they are analogous to-and currently the cleanest and best characterized model system for-Ziegler-type nanoparticles made from Co or Ni precatalysts plus AlEt3 whic...
The role of alkali-metal promotion on CO oxidation over PdO/SnO2 catalysts
MİRKELAMOĞLU, BURCU; Karakaş, Gürkan (Elsevier BV, 2006-01-17)
Sol-gel prepared PdO/SnO2 and Na-PdO/SnO2 catalysts were investigated by X-ray photoelectron spectroscopy (XPS), diffuse reflectance IR (DRIFTS), temperature-programmed reaction spectroscopy (TPRS) and impulse techniques. Alkali-metal promotion was observed to enhance CO oxidation rate and decreases light-off temperatures of PdO/SnO, XPS analysis revealed that alkali-metal promotion resulted in the segregation of Pd atoms and promoted the oxygen storage capacity of the catalysts. The presence of super-oxide...
Determination of the dispersion of supported Pt particles by gas-phase and liquid-phase measurements
Kivrak, Hilal; Mastalir, Agnes; Kiraly, Zoltan; Üner, Deniz (Elsevier BV, 2009-02-15)
The dispersion of a Pt/gamma-Al2O3 catalyst was investigated by various experimental techniques. The values obtained by gas-phase hydrogen and carbon monoxide adsorption and transmission electron microscopy (TEM) were consistent for the metal:adsorbate stoichiometry of 1:1. However, these methods overestimated the number of active sites available for a liquid-phase reaction. For the hydrogenation of styrene in the presence Of CS2 as a catalyst poison, only the defect sites were found to be active in the cat...
Palladium(0) nanoparticles supported on polydopamine coated CoFe2O4 as highly active, magnetically isolable and reusable catalyst for hydrogen generation from the hydrolysis of ammonia borane
Manna, Joydev; Akbayrak, Serdar; Özkar, Saim (Elsevier BV, 2017-07-05)
Palladium(0) nanoparticles supported on cobalt ferrite (Pd degrees/CoFe2O4) are found to be highly active catalyst, providing an unprecedented catalytic activity with a turnover frequency of 290 min(-1) in hydrogen generation from the hydrolysis of ammonia borane at room temperature. However, the initial catalytic activity of Pd degrees/CoFe2O4 catalyst is not preserved after the reuse of the catalyst in hydrolytic dehydrogenation of ammonia borane. The stability of the catalyst is improved by using the pol...
Citation Formats
IEEE
ACM
APA
CHICAGO
MLA
BibTeX
D. Üner, I. Ozen, and M. Uner, “Oxygen adsorption on Pt/TiO2 catalysts,”
APPLIED CATALYSIS A-GENERAL
, pp. 225–234, 2003, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/43464.