title: Surface energy of solid catalysts measured by inverse gas chromatography.
abstract: The time separation of experimental surface energy on Pt-Rh bimetallic catalysts, together with the time-independent rate constants for adsorption and desorption of O(2), CO, and CO(2) on them, is described, applying the reversed-flow version of inverse gas chromatography. The standard free energy of adsorption DeltaG(z.plims;) and its probability density function over time, together with the geometrical mean of the London parts of the total surface free energy (gamma(L)(1)gamma(L)(2))(1/2) of the adsorbed probe and the solid surface, accompanied by the relevant probability density functions over time are also calculated. The time-resolved phenomena lead to quite varying values of DeltaG(z.plims;), (gamma(L)(1)gamma(L)(2))(1/2), and the distribution functions as time passes, their maximum values being given by the catalyst containing a Pt:Rh = 3:1 weight ratio of the active phase for all adsorbed gases. The conclusion is reached that the surface energy measured as described can be used as a good measure for catalyst characterization.
authors.affiliation: Department of Chemistry, University of Patras, 26504 Patras, Greece. rita@chemistry.upatras.gr
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Katsanos
authors.forename: Demetrius
authors.initials: D
authors.lastname: Gavril
authors.forename: John
authors.initials: J
authors.lastname: Kapolos
authors.forename: George
authors.initials: G
authors.lastname: Karaiskakis