Cardinal Engineering (United States)

Abstract Toward the development of a “green” technology for cleaning soil contaminated by halogenated hydrophobic organic contaminants, here we demonstrate that combined use of palladium (Pd) and rhodium (Rh) catalysts enables the conversion of 1,2,4,5-tetrachlorobenzene (TeCB) to cyclohexane in mixtures of water and ethanol. We tested the hypotheses that, in batch reactors, (1) an increased ratio of water to ethanol in water/ethanol solvents would increase the reaction rates of both Pd-catalyzed hydrodehalogenation (HDH) and Rh-catalyzed hydrogenation, and (2) catalytic reaction rate coefficients would be constant above a hydrogen (H2) pressure threshold, but would decrease with decreasing H2 pressure below that threshold. These hypotheses were derived from a Langmuir–Hinshelwood model for the heterogeneous catalytic reactions. Complete conversion of TeCB to cyclohexane was achieved at all experimental conditions tested, suggesting that the proposed technology may be technically viable. Concentration dat...