Effect of Surface and Oxygen Coverage on Ethylene Epoxidation

Özbek, MO Murat; Önal, Işık; Santen, van Ra Rutger

doi:10.1007/s11244-012-9870-7

Cited by 48 publications

(55 citation statements)

References 59 publications

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“…Despite this discrepancy, numerous density functional theory (DFT) calculations have been performed on the mechanism of ethylene epoxidation on silver with adsorbed atomic oxygen on unreconstructed Ag surfaces. These have revealed, in agreement with kinetic isotope studies [27], that epoxidation and combustion can proceed through a common intermediate [28][29][30][31][32][33].…”

Section: Introductionsupporting

confidence: 82%

“…The activation energy for this elementary step is only 0.29 eV, significantly less than that observed for other OMC decomposition pathways on silver [33]. We find that the barrier is reduced by the dynamics of the reconstruction.…”

Section: Ethylene Oxidation On the P(4x4) Reconstruction Of Ag(111)contrasting

confidence: 57%

“…Table 1 for other energies. Once the OMC has formed it can isomerize to EO and AcH, as has been calculated for ethylene epoxidation with adsorbed atomic oxygen on the unreconstructed surface [28][29][30][31][32][33]. However, unlike adsorbed atomic oxygen on the unreconstructed surface, where the EO and AcH activation energies are nearly equal, the barrier to EO formation is significantly higher than that associated with AcH formation on this reconstructed Ag(110) surface, 1.08 eV and 0.66 eV,…”

Section: Ethylene Oxidation On the P(2x1)-reconstructed Ag(110) Surfacementioning

confidence: 77%

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Oxidation of Ethylene on Oxygen Reconstructed Silver Surfaces

et al. 2016

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We report on theoretical and experimental studies of the reactivity of ethylene with oxygen in two well-known oxygen induced surface reconstructions on silver, the p(2x1) reconstruction on the Ag(110) and the p(4x4) reconstruction on the Ag(111) surfaces. Density functional theory calculations demonstrate that ethylene can react with oxygen on both surfaces to form an oxametallacycle that can decompose into either ethylene oxide or a CO 2 precursor, acetaldehyde.The activation energy associated with acetaldehyde formation is predicted to be 0.4 eV lower than that associated with epoxide formation on both surfaces, though we find lower barriers for all elementary steps on the p(4x4) reconstruction due to its unique structural dynamics. Our calculations predict these dynamics make the p(4x4) reconstruction active in acetaldehyde formation at room temperature. Experiments performed by exposing the p(4x4) reconstruction to ethylene at room temperature support this finding with CO 2 the only carbonaceous product formed during temperature programed desorption. Our results unambiguously demonstrate that, alone, these oxygen reconstructions are not selective in ethylene epoxidation on silver.

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Section: Introductionsupporting

confidence: 82%

Section: Ethylene Oxidation On the P(4x4) Reconstruction Of Ag(111)contrasting

confidence: 57%

Section: Ethylene Oxidation On the P(2x1)-reconstructed Ag(110) Surfacementioning

confidence: 77%

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Oxidation of Ethylene on Oxygen Reconstructed Silver Surfaces

et al. 2016

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“…Besides the formation of the surface intermediates, the basic character of the adsorbed oxygen over the metal surface directs the reaction route to either oxametallacycle intermediates or ally radical leading to the complete combustion reaction [8,25]. A direct epoxidation path that selectively produces ethylene oxide enabled by the electrophilic oxygen on the Ag 2 O surface has been reported recently [2,3,[28][29][30]. All this parameters are important for epoxidation of alkenes.…”

Section: Introductionmentioning

confidence: 99%

A density functional theory study of propylene epoxidation on RuO2(110) surface

Atmaca

Düzenli

Özbek

et al. 2016

Applied Surface Science

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“…It is almost clear that this state does not correspond to mere metallic silver and is more than a simple oxygen adsorption system. Since the interaction between oxygen and silver is believed to play an essential role in understanding ethylene epoxidation, the effect of surface and sub-surface oxygen coverage on EO selectivity has been subject to extended debate [13,[23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%