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 activated 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°C, 5 bar, 1.3 g cat min/mmol TTCE 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 electronic microscopy, thermogravimetry, X-ray photoelectron spectroscopy, temperature-programmed oxidation and temperature-programmed reduction. Characterisation results indicate that the deactivation is caused mainly by the formation of carbonaceous deposits.