Surface energy of solid catalysts measured by inverse gas chromatography

• Published in: Journal of colloid and interface science 2004-02, Vol.270 (2), p.455-461
• Main Authors: Katsanos, Nicholas A., Gavril, Demetrius, Kapolos, John, Karaiskakis, George
• Format: Article
• Language: English
• Subjects: Catalysis; Catalyst characterization; Chemistry; Exact sciences and technology; General and physical chemistry; Interface; Inverse gas chromatography; Surface energy; Surface physical chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2003.07.037

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 ΔG ⦵ and its probability density function over time, together with the geometrical mean of the London parts of the total surface free energy ( γ L 1 γ 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 ΔG ⦵ , ( γ L 1 γ 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.