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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