Temkin-type model for the description of induced heterogeneity: CO adsorption on group 4 transition metal dioxides
Articolo
Data di Pubblicazione:
1993
Abstract:
CO a-coordinated at room temperature on the virtually homogeneous surfaces of some titania and
zirconia preparations (showing only one kind of coordinatively unsaturated Me4+) reveals the occurrence
of inductive effects among adspecies, as witnessed by the red shift of the stretching frequency and the
decrease of the heat of adsorption with increasing coverage. A generalized version of the Temkin equation
represents satisfactorily the adsorption isotherm and allowed the calculation of the repulsion energy
among adparticles. With structurally heterogeneous surfaces (other preparations of titania, zirconia and
hafnia) showing two or three types of coordinatively unsaturated Me4+ cations, revealed by a multiplicity
of CO bands, the same model satisfactorily applies to the individual isotherms and also provides evidence
that the distribution of the sites is not patchwise. Standard adsorption entropies hasof or both one-species
and multispecies systems show a linear dependence upon standard enthalpy, constituting a
compensation effect in the free enthalpy term.
Tipologia CRIS:
03A-Articolo su Rivista
Keywords:
titania; zirconia; in-situ FTIR spectroscopy; adsorption microcalorimetry; CO adsorption; Temkin-type model
Elenco autori:
V. BOLIS; C. MORTERRA; B. FUBINI; P. UGLIENGO; E. GARRONE
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