Chloroform Hydrodechlorination Behavior of Alumina-supported Pd and PdAu Catalysts

Significance Chloroform is a common groundwater contaminant that is very difficult to remove. Chemically converting it into a less toxic form through heterogeneous catalysis is an attractive approach over conventional physical removal methods if it can be done economically. In this study, we explore the efficacy of supported precious metal catalysts for chloroform hydrodechlorination. We find that Pd/Al2O3 is catalytically active for this reaction (6.4 L/g(Pd)/min) at room temperature, atmospheric pressure, in buffered water, and in the presence of hydrogen gas, and that Pd deposited on commercial Au/Al2O3 shows activities as high as 22.4 L/g(Pd)/min, suggestive of some Pd metal located on top of Au domains. The primary reaction product is methane, with selectivity values exceeding 90%. Surface-enhanced Raman spectroscopy shows evidence of chloroform adsorption and dechlorination on the catalyst surface under aqueous conditions. The results highlight the potential of ambient-condition reductive catalysis to remove chloroform from water. (c) 2013 American Institute of Chemical Engineers AIChE J, 59: 4474-4482, 2013