Résumé
Exfoliated graphite nanoplatelets (xGnPs) are proposed as a support material in the design of hierarchical Pd-based nanocatalysts for reductive dehalogenation. xGnP-supported metallic (Pd) and bimetallic (Pd-Au) catalysts were synthesized and evaluated in experiments on dehalogenation of trichloroethylene (TCE) in batch and membrane reactors. The TCE removal of 96% was achieved with Pd-Au/xGnP-filled membranes operated at the specific permeate flux of 47.4 L m(-2) h(-1) bar(-1). Normalized reactive fluxes in flow-through dehalogenation by membranes with embedded Pd-Au/xGnP and Pd/xGnP catalysts were 14.71 +/- 5.96 and 2.56 +/- 1.79 m s(-1) M-H2(-1) g(Pd)(-1) gPSf, respectively. These values were similar to 80 and similar to 14 times higher than the normalized reactive flux obtained using membranes with embedded commercial Pd/Al2O3 catalyst. To our knowledge, this is the first report on Pd and Pd-Au catalysts on a graphene-type support for hydro-dechlorination and the first demonstration of high throughput TCE dechlorination in a membrane reactor. Determined for batch reactions, the second order reaction rate constants for Pd-Au/xGnP and Pd/xGnP catalysts were 26 309 +/- 6555 and 9975 +/- 9506 M-H2(-1) s(-1) g(Pd)(-1) L. These values were similar to 81 and similar to 31 times higher than the rate constant obtained for the commercial Pd/Al2O3 catalyst.