Effective Pd/C catalyst for chlorobenzene and hexachlorobenzene hydrodechlorination by direct pyrolysis of sawdust impregnated with palladium nitrate

•Pd(NO3)2 impregnated sawdust was used as a catalyst precursor.•Two Pd/C catalysts were prepared by pyrolysis with different temperature ramps.•They contain amorphous carbon and Pd0 nanoparticles partially decorated with carbon.•Milder pyrolysis conditions lead to smaller and less carbon decorated Pd particles.•Such catalyst is better in gas- and especially liquid-phase hydrodechlorination.

Two Pd/C catalysts were prepared by pyrolysis of Pd(NO3)2 impregnated sawdust. At equal pyrolysis time slow ramping with shorter isothermal heating resulted in 0.9 wt.% Pd/C-S1 sample comprising carbon support with some oxygen-containing moieties and Pd0 with 2.6 nm average particle size (APS) partially decorated with carbon shell, whereas fast temperature ramping and long isothermal heating provided 0.6 wt.% Pd/C-S2 containing Pd0 with 3.7 nm APS, with larger fraction of carbon decorated particles. Pd/C-S1 is slightly more efficient than Pd/C-S2 in gas phase chlorobenzene hydrodechlorination to benzene at 100–250 °C. Only Pd/C-S1 provides hexachlorobenzene hydrodechlorination in liquid phase due to lower APS and probably smaller PdCx content.

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