Enhanced Pd pillared clays by Rh inclusion for the catalytic hydrodechlorination of chlorophenols in water.

Bimetallic Pd-Rh catalysts supported on pillared clays have been prepared and tested for aqueous-phase hydrodechlorination (HDC) using 4-chlorophenol (4-CP) as target compound. These bimetallic catalysts combine the higher activity of Rh with the better stability of Pd found in previous works with monometallic catalysts. Different combinations of Pd and Rh amounting to 1 wt% total metal load were tested and the catalyst with 0.75 wt% Pd and 0.25 wt% Rh yielded the best results. Ecotoxicity and biodegradability (measured as BOD(5)/COD ratio) of the effluents were checked. A significant decrease of ecotoxicity was observed while biodegradability was dramatically improved from 0.02 for the initial 4-CP solution up to values higher than 0.6.