Pd–Fe/SiO2 and Pd–Fe/Al2O3 catalysts for selective hydrodechlorination of 2,4-dichlorophenol into phenol

•Hydrodechlorination of chlorophenols was conducted on Pd/SiO2 and Pd/Al2O3 catalysts.•Addition of Fe to Pd/SiO2 and Pd/Al2O3 catalysts limited the formation of cyclohexanone.•XPS and TPR-H2 studies of bimetallic systems revealed the presence of PdxFey phases.•Catalytic properties strongly depend on the dispersion of the active phase.

The effect of iron introduction on the activity and selectivity of chemically precipitated supported palladium catalysts in the hydrodechlorination of 2,4-dichlorophenol in liquid phase at room temperature was studied. Bimetallic Pd–Fe catalysts supported on silica and alumina were characterized by using XPS, XRD, ToF-SIMS and TPR-H2 techniques. The dispersion of active phase in catalytic systems was examined by XRD and chemisorption of CO gas. Bimetallic Pd–Fe/SiO2 and Pd–Fe/Al2O3 catalysts containing 5 wt.% of Pd and 1–20 wt.% of Fe demonstrated high activity and high selectivity to phenol. However, Pd–Fe/Al2O3 catalysts with higher dispersion of the active phase were less active in the studied reaction than Pd–Fe/SiO2 systems, but selectivity to phenol was comparable for both types of bimetallic catalysts. The stability of Pd–Fe/SiO2 systems was higher than the bimetallic Pd–Fe/Al2O3 catalysts but selectivity to phenol decreases for that system systematically in each cycle of reaction, reaching only about 40% in the tenth cycle. It was also found that the addition of Fe to palladium catalysts limited the formation of cyclohexanone in the reaction medium.

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