Ethanol reactions over the UO2(111) single crystal

effect of the Madelung potential on the reaction selectivity

S V Chong, T R Griffiths, Hicham Idriss

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

The reactions of ethanol on UO2(111) single crystal have been investigated by temperature programmed desorption (TPD) while the surface characteristics were studied by Auger electron spectroscopy and low energy electron diffraction. Ethanol-TPD indicated products desorption in two temperature domains (at 370 and 570 K), with a coincident desorption of ethanol, ethylene and acetaldehyde at the high temperature region. The sticking coefficient of ethanol at 300 K is found equal to 0.6+/-0.2 at zero coverage and decreases to ea. 10(-2) near saturation. The ratio acetaldehyde/ethylene of 0.8+/-0.05 indicates 'equal' sites for dehydration and dehydrogenation reactions. This ratio was affected neither by changing ethanol coverage nor by pre-dosing the surface with O-2. The comparison of the reaction pathways of ethanol over UO2(111), from this work, with that of other well-defined oxides indicated an inverse linear relationship between the dehydrogenation/dehydration pathway over TiO2(001) [Kim and Barteau, J. Mol. Catal. 63 (1990) 103], ZnO(0001) [Vohs and Barteau, Surf. Sci. 221 (1989) 590], Cu2O(100) [Schulz and Cox, J. Phys. Chem. 97 (1993) 647], ZrO2(110) [Dilara and Vohs, Surf. Sci. 321 (1994) 8] and UO2(111) single crystals and their dielectric constant as well as the corresponding Madelung potentials. (C) 2000 Elsevier Science B.V. All rights reserved.

Original languageEnglish
Pages (from-to)187-198
Number of pages12
JournalSurface Science
Volume444
Issue number1-3
DOIs
Publication statusPublished - 1 Jan 2000

Keywords

  • Auger electron spectroscopy
  • Madelung potentials
  • single crystal surfaces
  • sticking
  • uranium dioxide
  • TEMPERATURE-PROGRAMMED DESORPTION
  • SURFACE
  • OXIDE
  • CATALYSTS
  • URANIUM
  • OXIDATION
  • OXYGEN
  • ADSORPTION
  • 1-PROPANOL
  • MOLECULES
  • uranium dioxide
  • MOLECULES

Cite this

Ethanol reactions over the UO2(111) single crystal : effect of the Madelung potential on the reaction selectivity. / Chong, S V ; Griffiths, T R ; Idriss, Hicham.

In: Surface Science , Vol. 444, No. 1-3, 01.01.2000, p. 187-198.

Research output: Contribution to journalArticle

Chong, S V ; Griffiths, T R ; Idriss, Hicham. / Ethanol reactions over the UO2(111) single crystal : effect of the Madelung potential on the reaction selectivity. In: Surface Science . 2000 ; Vol. 444, No. 1-3. pp. 187-198.
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abstract = "The reactions of ethanol on UO2(111) single crystal have been investigated by temperature programmed desorption (TPD) while the surface characteristics were studied by Auger electron spectroscopy and low energy electron diffraction. Ethanol-TPD indicated products desorption in two temperature domains (at 370 and 570 K), with a coincident desorption of ethanol, ethylene and acetaldehyde at the high temperature region. The sticking coefficient of ethanol at 300 K is found equal to 0.6+/-0.2 at zero coverage and decreases to ea. 10(-2) near saturation. The ratio acetaldehyde/ethylene of 0.8+/-0.05 indicates 'equal' sites for dehydration and dehydrogenation reactions. This ratio was affected neither by changing ethanol coverage nor by pre-dosing the surface with O-2. The comparison of the reaction pathways of ethanol over UO2(111), from this work, with that of other well-defined oxides indicated an inverse linear relationship between the dehydrogenation/dehydration pathway over TiO2(001) [Kim and Barteau, J. Mol. Catal. 63 (1990) 103], ZnO(0001) [Vohs and Barteau, Surf. Sci. 221 (1989) 590], Cu2O(100) [Schulz and Cox, J. Phys. Chem. 97 (1993) 647], ZrO2(110) [Dilara and Vohs, Surf. Sci. 321 (1994) 8] and UO2(111) single crystals and their dielectric constant as well as the corresponding Madelung potentials. (C) 2000 Elsevier Science B.V. All rights reserved.",
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T2 - effect of the Madelung potential on the reaction selectivity

AU - Chong, S V

AU - Griffiths, T R

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PY - 2000/1/1

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N2 - The reactions of ethanol on UO2(111) single crystal have been investigated by temperature programmed desorption (TPD) while the surface characteristics were studied by Auger electron spectroscopy and low energy electron diffraction. Ethanol-TPD indicated products desorption in two temperature domains (at 370 and 570 K), with a coincident desorption of ethanol, ethylene and acetaldehyde at the high temperature region. The sticking coefficient of ethanol at 300 K is found equal to 0.6+/-0.2 at zero coverage and decreases to ea. 10(-2) near saturation. The ratio acetaldehyde/ethylene of 0.8+/-0.05 indicates 'equal' sites for dehydration and dehydrogenation reactions. This ratio was affected neither by changing ethanol coverage nor by pre-dosing the surface with O-2. The comparison of the reaction pathways of ethanol over UO2(111), from this work, with that of other well-defined oxides indicated an inverse linear relationship between the dehydrogenation/dehydration pathway over TiO2(001) [Kim and Barteau, J. Mol. Catal. 63 (1990) 103], ZnO(0001) [Vohs and Barteau, Surf. Sci. 221 (1989) 590], Cu2O(100) [Schulz and Cox, J. Phys. Chem. 97 (1993) 647], ZrO2(110) [Dilara and Vohs, Surf. Sci. 321 (1994) 8] and UO2(111) single crystals and their dielectric constant as well as the corresponding Madelung potentials. (C) 2000 Elsevier Science B.V. All rights reserved.

AB - The reactions of ethanol on UO2(111) single crystal have been investigated by temperature programmed desorption (TPD) while the surface characteristics were studied by Auger electron spectroscopy and low energy electron diffraction. Ethanol-TPD indicated products desorption in two temperature domains (at 370 and 570 K), with a coincident desorption of ethanol, ethylene and acetaldehyde at the high temperature region. The sticking coefficient of ethanol at 300 K is found equal to 0.6+/-0.2 at zero coverage and decreases to ea. 10(-2) near saturation. The ratio acetaldehyde/ethylene of 0.8+/-0.05 indicates 'equal' sites for dehydration and dehydrogenation reactions. This ratio was affected neither by changing ethanol coverage nor by pre-dosing the surface with O-2. The comparison of the reaction pathways of ethanol over UO2(111), from this work, with that of other well-defined oxides indicated an inverse linear relationship between the dehydrogenation/dehydration pathway over TiO2(001) [Kim and Barteau, J. Mol. Catal. 63 (1990) 103], ZnO(0001) [Vohs and Barteau, Surf. Sci. 221 (1989) 590], Cu2O(100) [Schulz and Cox, J. Phys. Chem. 97 (1993) 647], ZrO2(110) [Dilara and Vohs, Surf. Sci. 321 (1994) 8] and UO2(111) single crystals and their dielectric constant as well as the corresponding Madelung potentials. (C) 2000 Elsevier Science B.V. All rights reserved.

KW - Auger electron spectroscopy

KW - Madelung potentials

KW - single crystal surfaces

KW - sticking

KW - uranium dioxide

KW - TEMPERATURE-PROGRAMMED DESORPTION

KW - SURFACE

KW - OXIDE

KW - CATALYSTS

KW - URANIUM

KW - OXIDATION

KW - OXYGEN

KW - ADSORPTION

KW - 1-PROPANOL

KW - MOLECULES

KW - uranium dioxide

KW - MOLECULES

U2 - 10.1016/S0039-6028(99)01030-4

DO - 10.1016/S0039-6028(99)01030-4

M3 - Article

VL - 444

SP - 187

EP - 198

JO - Surface Science

JF - Surface Science

SN - 0039-6028

IS - 1-3

ER -