Liquid phase dioxin hydrodechlorination over Pd/γ–Al2O3

Liquid phase hydrodechlorination of dioxins and furans over Pd/Al2O3 was studied at 75 °C under nitrogen and air environments, using 2-propanol as solvent as well as hydrogen donor. The pH of reaction was maintained by addition of NaOH. More chlorinated congeners readily transformed into less chlorinated ones during the first minutes of reaction, so less chlorinated congeners took a larger time for their complete degradation. Under air atmosphere, initial hydrodechlorination reaction rates were slower than under inert conditions since oxygen competes with chlorinated compounds for hydrogen. However, 99.9% conversion was achieved after about 3 h and toxicity decreased to 98.5% under both inert and air atmospheres. Fresh and used catalyst samples were characterized by elemental analysis, nitrogen adsorption, hydrogen chemisorption, XRD and TPR. No clear evidence of Pd leaching was obtained. However, BET surface area and Pd dispersion decreased on used samples.