Catalytic hydrodechlorination reactivity of monochlorophenols in aqueous solutions over palladium/carbon catalyst

Monochlorophenols (CPs) were completely hydrodechlorinated with 5% Pd/C in aqueous solutions at room temperature under atmospheric pressure. In the hydrogenation process, 2-CP, 3-CP and 4-CP showed different clechlorination reactivity. It was found the C-Cl bond in the ortho position of hydroxyl group was the most difficult clechlorination in the hydrogenation of monochlorophenols in aqueous solutions compared to those in meta and para positions. Additionally. bases and solvents also had influences on the hydrodechlorination reactivity and selectivity of monochlorophenols as well as the activity of the catalyst. In aqueous solutions, it was more advantageous to the hydrodechlorination of monochlorophenols during the hydrogenation due to the cleaning function of water. Furthermore, the presence of bases, especially for sodium hydroxide, also ensured the high activity of the catalyst in water. (C) 2008 Elsevier B.V. All rights reserved.