Coverage-dependent kinetics and thermodynamics of carbon monoxide adsorption on a ternary copper catalyst derived from static adsorption microcalorimetry

Xinyu Xia, Raoul Naumann d'Alnoncourt, Jennifer Strunk, Sergey Litvinov, Martin Muhler

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16 Scopus citations

Abstract

A reliable method for adsorption systems in equilibrium is established to derive coverage-dependent kinetics and thermodynamics from the volumetric data obtained during the static microcalorimetric measurement of heats of adsorption. The Wigner-Polanyi equation is applied to analyze the pressure change as a function of time during stepwise dosing of the adsorptive until thermodynamic adsorption-desorption equilibrium is established. For carbon monoxide adsorption on a hydrogen-reduced Cu/ZnO/Al2O3 catalyst, the adsorption rate constant (ka) is found to be in the range from 10-6 to 10-4 Pa-1 s-1, and the desorption rate constant (kd) from 10-4 to 10-2 s-1, both increasing with fractional coverage θ. The kinetically derived equilibrium constant K(θ) is in good agreement with K(θ) obtained from the adsorption isotherm. RT ln(Kp0) and the differential heat of adsorption (qdiff) were found to decrease in parallel, reflecting a normal Temkin-type heterogeneity.

Original languageEnglish
Pages (from-to)8409-8415
Number of pages7
JournalJournal of Physical Chemistry B
Volume110
Issue number16
DOIs
StatePublished - 27 Apr 2006
Externally publishedYes

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