(143ae) Catalytic Hydrodechlorination over Pd Supported on Amorphous and Structured Carbon

The gas phase catalytic hydrodechlorination (HDC) of chlorobenzene has been studied (T = 423 K) over Pd (8 ±1 % w/w) supported on activated carbon (Pd/AC), graphite (Pd/Graphite) and graphitic carbon nanofibers (Pd/GNF). The activated carbon (875 m2 g-1) and graphite (11 m2 g-1) substrates were obtained from a commercial source but the carbon nanofibers (74 m2 g-1) were synthesized via ethylene decomposition over unsupported Ni to yield a mean fiber diameter = 225 nm. Under identical reaction conditions, the following initial HDC activity sequence has been established: Pd/GNF ≈ Pd/AC > Pd/Graphite. HDC activity declined with time-on-stream (four reaction cycles were considered) where Pd/GNF maintained a significantly higher fractional HDC and Pd/AC activity decreased continually to converge with Pd/Graphite at a common residual conversion. The pre- and post- reaction catalyst samples have been characterized by BET area/pore size analysis, TPR, TEM, SEM, H2 chemisorption/TPD, XRD and acid/base titration. Pd size distribution is given in each case where surface area-weighted Pd diameter increased in the order: Pd/Graphite