The nature of low temperature deactivation of CoCr2O4 and CrOx/-Al2O3 catalysts for the oxidative decomposition of trichloroethylene

Abstract

The CoCr2O4 and CrOx/gamma-Al2O3 catalysts were used for the oxidative decomposition of trichloroethylene (TCE). Both catalysts showed an initial deactivation at low temperatures around 280degreesC, mainly due to the dissociative adsorption of reactant TCE. This was confirmed by the temperature programmed oxidation of TCE where the carbon oxides were formed up to a temperature below 300degreesC. Possible changes in the oxidation state of chromium species were observed with XANES and ESR. During the oxidation reaction at low temperatures, the Cr(VI) species were reduced to Cr(III) species, which seemed to be coupled with TCE adsorption. At higher temperatures, however, the Cr(VI) species appeared again and the catalytic activity was completely recovered. (C) 2003 Elsevier B.V. All rights reserved.