n-Alkanes on MgO(100). I: Coverage-Dependent Desorption Kinetics of n-Butane

Journal Article · Fri Apr 22 04:00:00 EDT 2005 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.1883629· OSTI ID:15016797

Tait, Steven L; Dohnalek, Zdenek; Campbell, C T; Kay, Bruce D

High quality temperature programmed desorption (TPD) measurements of n-butane from MgO(100) have been made for a large number of initial butane coverages (0-3.70 ML) and a wide range of heating ramp rates (0.3-10 K/s). We present a TPD analysis technique which allows the coverage-dependent desorption energy to be accurately determined by mathematical inversion of a TPD spectrum, assuming only that the prefactor is coverage-independent. A variational method is used to determine the prefactor that minimizes the difference between a set of simulated TPD spectra and corresponding experimental data. The best fit for butane desorption from MgO is obtained with a prefactor of 1015.7?1.6 s-1. The desorption energy is 34.9?3.4 kJ/mol at 0.5 ML coverage, and varies with coverage. Simulations based on these results can accurately reproduce TPD experiments for submonolayer initial coverages over a wide range of heating ramp rates (0.3-10 K/s). Advantages and limitations of this method are discussed.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 15016797
• Report Number(s): PNNL-SA-43247; 2652; 6500; KC0301020
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 16 Vol. 122; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
BUTANE
DESORPTION
Environmental Molecular Sciences Laboratory
HEATING
KINETICS
MAGNESIUM OXIDES
SORPTIVE PROPERTIES
SPECTRA