Aqueous-phase hydrodechlorination and further hydrogenation of chlorophenols to cyclohexanone in water over palladium nanoparticles modified dendritic mesoporous silica nanospheres catalyst

Abstract

Dendritic mesoporous silica nanospheres (DMSNs) have been synthesised in this work. The distance of each “arborization” is 7 nm, which plays the role of “pore”. Hydrodechlorination (HDC) of 4-chlorophenol (4-CP) as the target compound using Pd modified DMSNs as the catalyst (Pd/DMSNs) is carried out in aqueous sodium hydroxide solution under atmospheric H₂ pressure, fairly mild conditions for a potential application to treat industrial wastewater. Compared with some supported Pd catalysts, Pd/DMSNs exhibit an improved catalytic performance, owing to the specific dendritic structure, which can improve mass transfer, and increase the adsorption–desorption rate of compounds. In this work, both the dechlorination process and further hydrogenation process of 4-CP are studied under various conditions including different catalyst dosages and different temperatures. By analyzing the experimental results, it is clear that the influential factors mentioned above have a strong impact on the selectivity of the HDC experiment. In addition, 2-CP, 3-CP, and 2,4-DCP are also tested as target pollutants.