Energetics of Cyclohexene Adsorption and Reaction on Pt(111) by Low-Temperature Microcalorimetry
| Autor: | Ole Lytken, Jonathan J W Harris, Wanda Lew, J. Michael Gottfried, Ebbe K. Vestergaard, Charles T. Campbell |
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| Rok vydání: | 2008 |
| Předmět: |
Isothermal microcalorimetry
Inorganic chemistry Cyclohexene General Chemistry Calorimetry Atmospheric temperature range Biochemistry Catalysis Standard enthalpy of formation chemistry.chemical_compound Colloid and Surface Chemistry Adsorption chemistry Physical chemistry Sigma bond Sticking probability |
| Zdroj: | Journal of the American Chemical Society. 130:10247-10257 |
| ISSN: | 1520-5126 0002-7863 |
| DOI: | 10.1021/ja801856s |
| Popis: | The heat of adsorption and sticking probability of cyclohexene on Pt(111) were measured as a function of coverage using single-crystal adsorption calorimetry in the temperature range from 100 to 300 K. At 100 K, cyclohexene adsorbs as intact di-sigma bonded cyclohexene on Pt(111), and the heat of adsorption is well described by a second-order polynomial (130 - 47 theta - 1250 theta(2)) kJ/mol, yielding a standard enthalpy of formation of di-sigma bonded cyclohexene on Pt(111) at low coverages of -135 kJ/mol and a C-Pt sigma bond strength of 205 kJ/mol. At 281 K, cyclohexene dehydrogenates upon adsorption, forming adsorbed 2-cyclohexenyl (c-C6H(9,a)) and adsorbed hydrogen, and the heat of adsorption is well described by another second-order polynomial (174 - 700 theta + 761 theta(2)) kJ/mol. This yields a standard enthalpy of formation of adsorbed 2-cyclohexenyl on Pt(111) at a low coverage of -143 kJ/mol. At coverages below 0.10 ML, the sticking probability of cyclohexene on Pt(111) is close to unity (>0.95), independent of temperature. |
| Databáze: | OpenAIRE |
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