Characterisation of the deactivation of platinum and palladium supported on activated carbon used as hydrodechlorination catalysts

The deactivation of 0.5 wt.% Pd on activated carbon and 0.5 wt. % Pt on act ivated carbon catalysts for the hydrodechlorination of tetrachloroethylene (TTCE) in organic matrix has been studied. Experiments were carried out in a continuous fixed bed reactor at 250 degreesC, 5 bar, 1.3 g cat min/mmol T TCE and 0.8 Nl/min of hydrogen. Although both catalysts show certain degree of deactivation, this is more pronounced for the Pt catalyst. In order to study the causes of deactivation, fresh and used catalysts were characterised by nitrogen porosimetry, X-ray diffraction, transmission ele ctronic microscopy, thermogravimetry, X-ray photoelectron spectroscopy, tem perature-programmed oxidation and temperature-programmed reduction. Charact erisation results indicate that the deactivation is caused mainly by the fo rmation of carbonaceous deposits. (C) 2001 Elsevier Science B.V. All rights reserved.