Hydrogenation of Chlorobenzene to Cyclohexane over Colloidal Pt Nanocatalysts under Ambient Conditions

A series of finely dispersed poly(vinyl-2-pyrrolidone)-stabilized platinum colloidal nanocatalysts (PVP-Pt) were prepared and characterized by TEM. Hydrogenation of monochlorobenzene (MCB) was carried out in a batch mode using hydrogen over PVP-Pt at 298 K and atmospheric pressure. The product consisted of benzene and cyclohexane during the reaction, and nearly 100% selectivity to cyclohexane could be obtained at approximately 100% conversion of MCB. The catalytic performance of the PVP-Pt colloids is dependent on the preparation conditions. The small amount of the stabilizing polymer (PVP) in the preparation of colloidal platinum could not protect the platinum colloid commendably, but the large amount of PVP hindered the contact of reactant with catalyst surface and the desorption of product. Extra PVP added in the reaction system has some inhibiting effect on the reaction activity, and also resulting in some decrease in selectivity to cyclohexane. The reaction was verified to be first order to the concentration of MCB. The polymer-stabilized noble metal nanoparticles could be suitable to be hydrodehalogenation and reduction catalysts forthe remediation of various chloroaromatic compounds in the environment.