Poly(vinylpyrrolidone)-anchored Iridium Nanoparticles Supported on Al_2O_3 as Ultra-selective catalyst for the Hydrogenation of p-Chloronitrobenzene

摘要

Poly(vinylpyrrolidone)-anchored iridium nanoparticles (PVP-Ir) were prepared via the reduction of H_2Cl_6·nH_2O in ethanol/water mixtures. The catalytic properties of the colloidal nanoparticles that dispersed on Al_2O_3 (PVP-Ir/A_2O_3) were investigated in the selective hydrogenation of p-chloronitrobenzene(p-CNB) to p-chloroaniline (p-CAN). The results indicated that the selectivity to p-CAN remained on the level of 100 % at complete conversion of p-CNB at lower temperature of 288 K. Moreover, the side reaction of hydrogenolysis of the carbon-halogen bond was completely inhibited in the absence of promoters and inhibitors. The great improvement on activity and selectivity of PVP-Ir/Al_2O_3 was attributed to the highly and homogeneously dispersion of the iridium nanoparticles on the support Al_2O_3 and the addition of appropriate amount of water in organic solvents