Trichloroethylene Hydrodechlorination in Water Using Formic Acid as Hydrogen Source: Selection of Catalyst and Operation Conditions

This work studies the aqueous-phase hydrodechlorination of trichloroethylene (TCE), using formic acid (FA) as hydrogen source, over different Pd-based catalysts. Reactions have been performed in a batch reactor at mild conditions (300-340 K), using different FA/TCE ratios (from 10 to 450) and working with TCE concentrations close to saturation (1000 ppm). Different supports have been tested for Pd-based catalysts: activated carbon (AC), carbon nanofibers (CNF), high surface area graphites (HSAG), alumina and ZSM-5 zeolite, following their activity the order: 0.5%Pd/CNF > 0.5%Pd/HSAG> 0.5%Pd/Al2O3 > 0.5%Pd/ZSM-5 > 0.5%Pd/AC. This alternative hydrogen source is confirmed to be technically feasible for TCE, determining an optimum FA/TCE ratio of 35. Thus, high FA concentrations inhibit the reaction due to competitive adsorption of both reactants. Furthermore, the support must be carefully selected, since supports presenting very strong interactions with the TCE (such as the ACs) hinder the hydrodechlorination. (c) 2012 American Institute of Chemical Engineers Environ Prog, 32: 1217-1222, 2013