Chlorine and Caesium Promotion of Silver Ethylene Epoxidation Catalysts

Date

2013-02-01

Author

Ozbek, M. Olus
Önal, Işık
van Santen, Rutger A.

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

67
views

0
downloads

The effect of co-adsorbed Cs and Cl on the selectivity of ethylene epoxidation was studied computationally on an Ag2O(001) surface model. Cl blocks the oxygen vacant sites and prevents oxometallacycle (OMC) formation, which is responsible for aldehyde formation on the oxide surface. Cl also prevents unfavorable surface reconstruction induced by co-adsorption of ethylene. It also has a positive effect on the stability of selective oxygen species when Cs co-exists. Introduction of Cs on the Ag2O(001) surface results in the formation of CsOx-type of complexes in the absence of Cl. Whereas oxygen atom adsorption energies are increased, Cs also introduces surface oxygen vacancies that reduce catalyst selectivity. Cs and Cl co-exist on the surface in the form of CsClxOy complexes. Under reaction conditions, these complexes stabilize the oxide surface and reduce oxygen surface vacancy formation, which results in higher ethylene oxide (EO) selectivity.

Subject Keywords

Ag2O, Caesium, Chlorine, Ethylene oxide, Promotion

URI

https://hdl.handle.net/11511/29938

Journal

CHEMCATCHEM

DOI

https://doi.org/10.1002/cctc.201200690

Collections

Graduate School of Natural and Applied Sciences, Article

Suggestions

OpenMETU
Core

Epoxidation of Propylene on a [Ag14O9] Cluster Representing Ag2O (001) Surface: A Density Functional Theory Study Fellah, Mehmet Ferdi; Önal, Işık (2012-01-01) Density functional theory calculations were employed to study partial oxidation of propylene on a [Ag14O9] cluster representing Ag2O (001) surface for which positive effect for ethylene oxide formation has been reported in our earlier work at the same level of theory (Fellah et al., Catal Lett 141: 762, 2011). Propylene oxide (PO), propanal, acetone and G-allyl radical formation reaction mechanisms were investigated. P-allyl formation path and two propylene adsorption paths resulting in PO formation are com...
Epoxidation of Ethylene by Silver Oxide (Ag2O) Cluster: A Density Functional Theory Study Fellah, Mehmet Ferdi; van Santen, Rutger A.; Önal, Işık (2011-06-01) Density functional theory (DFT) calculations were employed to study epoxidation of ethylene on a [Ag14O9] cluster model representing silver oxide (001) surface. Theoretical results obtained in this study showed that formation paths of acetaldehyde and vinyl alcohol have higher activation barriers than that of ethylene oxide formation path on silver oxide (35 and 35 vs. 20 kcal/mol). Formation of the ethylene oxometallocycle intermediate is found to have a low probability on Ag2O(001) surface. The essential ...
Chloroacetonylation of C=C double bonds promoted by manganese(III) acetate Dengiz, Çağatay; BALCI, METİN (2012-02-01) The addition of acetylacetone to alkenes was performed using Mn(OAc)(3 center dot)2H(2)O in the presence of HCl. The intermediate formed was trapped by chloride. Removal of one of the acetyl groups with ammonia under very mild conditions provided compounds derived from chloroacetonylation of the double bonds.
Sorption of BB41 dye molecules using chitosan based particles from aqueous solutions: A kinetic and thermodynamic evaluation Demirtas, Hulya; Tasar, Seyda; Kaya, Fatih; Ozer, Ahmet (2022-08-01) In this study, starting from chitosan is a hydrophilic polymer with positively charged, it was aimed to produce chitosan-based particles and to be evaluated as a sorbent. Chitosan-based polymeric particles production was carried out by the precipitation-collection method from chitosan. Chitosan and chitosan-based sorbent were characterized. For this purpose, SEM and FTIR analyzes were used. Sorption activities of the chitosan-based polymeric particles were investigated for basic dye (basic blue 41, BB41). T...
Ethylene and acetaldehyde production by selective oxidation of ethanol using mesoporous V-MCM-41 catalysts Gucbilmez, Yesim; Doğu, Timur; Balci, Suna (2006-05-10) Vanadium-incorporated MCM-41 type catalytic materials, which were synthesized by a direct hydrothermal synthesis procedure, showed very high activity and high selectivity in the production of ethylene from ethanol in an oxidative process. Ethylene selectivity showed a significant increase with an increase in temperature over 300 degrees C, while relatively high acetaldehyde selectivities were observed at lower temperatures. An ethylene yield value of 0.66 obtained at 400 degrees C with an O-2/ethanol feed r...

Citation Formats

M. O. Ozbek, I. Önal, and R. A. van Santen, “Chlorine and Caesium Promotion of Silver Ethylene Epoxidation Catalysts,” CHEMCATCHEM, pp. 443–451, 2013, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/29938.