On the Dual Role of the Reactant during Aqueous Phase Hydrodechlorination of Trichloroethylene (HDC of TCE) using Pd supported on Swellable Organically Modified Silica (SOMS)

Abstract Herein, the dual role of trichloroethylene (TCE) in liquid-phase hydrodechlorination with Pd catalysts supported on swellable organically modified silica (SOMS), is investigated. Batch experiments with TCE-soaked Pd/SOMS showed 45% higher conversion after 4 h than dry Pd/SOMS, suggesting that TCE acts as a reactant and as a swelling-agent. Flow experiments performed with and without ethanol (external swelling-agent) exhibited similar steady-state activities, confirming that TCE itself can cause swelling. Moreover, flow experiments, regardless of whether the SOMS-supported Pd catalysts were pre-reduced or not, yielded similar steady-state conversions, suggesting that Pd(2+) is rapidly reduced by H2 dissolved in water during approach to steady-state. In-situ characterization performed under reaction conditions using time-resolved X-ray absorption spectroscopy confirmed the reduction of Pd(2+) species to Pd(0) by dissolved H2. Overall, this study shows economic viability of hydrodechlorination of TCE using Pd/SOMS by eliminating the need for an external swelling-agent as well as a catalyst pre-reduction step.