Aqueous phase hydrodechlorination of trichloroethylene using Pd supported on swellable organically modified silica (SOMS): Effect of support derivatization

Herein, the role of swellability and hydrophobicity of swellable organically modified silica (SOMS) in shielding Pd against deactivation due to HCl produced during hydrodechlorination (HDC) of trichloroethylene (TCE) is investigated. The extent of surface derivatization during sol gel synthesis of SOMS was found to directly impact the extent of hydrophobicity, swellability and surface area, as confirmed by infrared spectroscopy and N2 physisorption, respectively. Furthermore, after Pd impregnation, the resultant particle size, location, and atomic environment of Pd were also dictated by the extent of support derivatization such that the least derivatized material provided lowest protection to Pd from HCl. Post HCl-treatment, the batch activity rate constants decreased by 66% for the least derivatized sample and 17% for the most derivatized one, suggesting that hydrophobicity and swellability are essential for obtaining high resistance to HCl which could potentially impact the economic viability of HDC of TCE process.