Effects of alkaline additives on conversion of 2,4,5-trichlorophenol over Pd-Rh/C catalysts

Abstract

Effects of alkaline additives on conversion of 2,4,5-trichlorophenol (TCP) over Pd-Rh/C catalysts were studied at 80ºC and 1 Atm. The catalysts were prepared by incipient wetness impregnation of carbon support and characterized by BET surface area, temperature programmed reduction (TPR) and X-ray diffraction (XRD) methods. The dechlorination of TCP occurs mainly via two pathways: hydrodechlorination and hydrolysis. The dechlorination of TCP can be accelerated significantly by alkalis. The addition of alkali had increasing effect on the initial reaction rate, conversion and crystallite size of Pd. The initial TCP dechlorination activity without alkali was found to be in the following order: 0.97%Pd/C>0.8%Pd/0.19%Rh/C>0.98%Rh/C. The selectivities of mono and di-chlorophenol were also improved with Pd/C catalyst.