The role of Fe addition on the activity of Pd-containing catalysts in multiphase hydrodechlorination

Multiphase hydrodechlorination of 1,4-dichlorobenzene, hexachlorobenzene and 2,4,8-trichlorodibenzofurane was studied in the presence of Pd/C and Pd-Fe/C catalysts. The effect of the addition of a second metal to Pd/C was investigated. The content (1–12 wt.%) and ratio of metals were varied to determine their influence on catalytic activity, which was demonstrated to strongly depend on metal ratio in multiphase hydrodechlorination systems.Metal–metal interaction and structure of bimetallic particles were studied by magnetic measurements and TPR analysis. Bimetallic particles consisted of Pd-enriched PdFe alloy. Also Fe2O3 was presented on the surface of catalyst. Based on catalytic performance, magnetic measurements, and TPR, two aspects of the influence of iron addition were considered: (1) formation of Pd-enriched PdFe alloy, which resulted in an increase of catalytic activity of bimetallic catalysts in comparison with Pd/C; (2) formation of FeCl3 under HDC reaction condition, which prevented complete chlorination of palladium, possibly leading to its deactivation.