Elucidating the role of ethanol in aqueous phase hydrodechlorination of trichloroethylene over Pd catalysts supported on swellable organically modified silica (SOMS)

Abstract In this study, effect of ethanol on the performance of Pd supported on swellable organically modified silica (SOMS) for hydrodechlorination (HDC) of trichloroethylene (TCE) is investigated. SOMS is a hydrophobic material that swells to 3–4 times its original volume when contacted with organic solvents. Catalytic HDC of TCE suffers from inhibition due to HCl which is worsened by the slow removal of HCl from the hydrophobic pores of SOMS. Addition of ethanol resulted in swelling of SOMS matrix causing expansion of pores, thereby facilitating the removal of HCl. The inhibitory effect of HCl was alleviated by ethanol, without altering the HDC reaction pathway. Characterization using near-ambient pressure X-ray photoelectron spectroscopy and extended X-ray absorption fine structure showed the effect of ethanol on swellability and HCl removal, respectively. Lastly, a mechanism has been proposed for the uninhibited reaction, which exhibited first order kinetics with respect to TCE.