Journal of Chromatography A, 1116 (2006) 230–239 Characterization of ceria–zirconia mixed oxides as catalysts for the combustion of volatile organic compounds using inverse gas chromatography Eva D´ ıaz a , Beatriz de Rivas b , Rub´ en L ´ opez-Fonseca b , Salvador Ord´ o˜ nez a,∗ , Jos´ e I. Guti´ errez-Ortiz b a Department of Chemical and Environmental Engineering, University of Oviedo, Juli´ an Claver´ ıa s/n, 33006 Oviedo, Spain b Chemical Technologies for Environmental Sustainability Group, Department of Chemical Engineering, Faculty of Science and Technology, University of the Basque Country/EHU, P.O. Box 644, E-48080 Bilbao, Spain Received 31 January 2006; received in revised form 8 March 2006; accepted 8 March 2006 Available online 3 April 2006 Abstract Inverse gas chromatography (IGC) has been used in this work for characterizing the adsorption of different volatile organic compounds (VOCs) (1,2-dichloroethane (DCE), trichloroethylene (TCE), and n-hexane) over ceria–zirconia mixed oxides (Ce x Zr 1-x O 2 , with x = 0, 0.15, 0.5, 0.68, 0.8 and 1). These materials have shown to be very active catalysts for the deep oxidation of the studied VOCs in previous papers. The enthalpies of adsorption (-H ads ), adsorption isotherms (corresponding to the Henry region), and dispersive (γ D s ) and specific (I sp ) components of the surface energy for the adsorption of the investigated compounds are determined using IGC at infinite dilution. These chromatographic data and other surface parameters (surface area, oxygen storage capacity, surface acidity, and reducibility) are correlated with the activity and selectivity of these catalysts. As a result, for n-hexane, the catalytic activity is mainly correlated with the adsorption capacity of the solids, whereas the activity for chlorinated compounds oxidation (as well as the selectivity to oxidation products) depends on both oxygen storage capacity and specific interaction of the chlorinated compound with the surface. © 2006 Elsevier B.V. All rights reserved. Keywords: IGC; Trichloroethylene; 1,2-Dichloroethane; VOCs; Adsorption; Ceria–zirconia mixed oxides; Catalytic oxidation; n-hexane 1. Introduction Ceria-containing materials have been widely employed as automotive exhaust three-way catalysts, [1–4] and better cat- alytic performances can be obtained when the catalysts are based on ceria–zirconia solid solutions instead of on pure cerium oxide [1]. Ceria and zirconia play an integral role in providing oxy- gen storage which broadens the conversion efficiency for all three pollutants (NO x , CO and hydrocarbons) during rich/lean perturbations associated with the feedback control regulating the air-to-fuel ratio used by the engine. Additionally, the par- tial substitution of Ce 4+ with Zr 4+ in the CeO 2 lattice leads to improvements in its redox properties, thermal resistance, and ∗ Corresponding author. Tel.: +34 985 103 437; fax: +34 985 103 434. E-mail address: sordonez@uniovi.es (S. Ord ´ o˜ nez). catalytic behaviour at lower temperatures [3]. A large number of studies have been performed on this topic; however, less con- sideration has been given to examine the ceria–zirconia mixed oxides as potential catalysts for the combustion of chlorinated organic pollutants [5]. Pollution associated with volatile organic compounds (VOCs) is commonly found in industries using or producing organic solvents, including petroleum, printing, surface coat- ings, food, and dry cleaning processes [6]. Among VOCs, chlo- rinated volatile organic compounds (ClVOCs) require special attention owing to their toxicity, high stability, and widespread application in the industry; in fact, they have been produced com- mercially and used for many purposes in different industries, including the manufacture of herbicides, plastics, and solvents. Among the ClVOCs emitted in industrial waste gas streams, 1,2- dichloroethane (DCE) and trichloroethylene (TCE) have been chosen as model compounds. DCE is a major component in the 0021-9673/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.chroma.2006.03.043