Pt/Al 2 O 3 Catalyst Prepared from Water-in-Oil Microemulsion and Used in Catalytic Hydrogenation

Abstract

Pt/Al₂O₃ catalyst was prepared from a cetyltrimethylammonium bromide (CTAB)/n-butanol/cyclohexane water-in-oil (w/o) microemulsion. The preparation conditions of Pt/Al₂O₃ catalyst were investigated and are discussed in detail. Transmission electron microscopy (TEM) showed uniform Pt nanoparticles (about 3 nm) with high dispersion in the catalyst. The Pt/Al₂O₃ catalyst exhibited excellent catalytic properties in the liquid-phase hydrogenation of o-chloronitrobenzene (o-CNB) to o-chloroaniline (o-CAN). After 60-min reaction at normal pressure and 303 K, the conversion of o-CNB was 81.1% and the selectivity to o-CAN was 96.2%. Kinetic study showed o-CNB hydrogenation to be a first-order reaction with an apparent activation energy of 56.37 kJ mol⁻¹. The microemulsion-derived catalyst shows a higher catalytic activity than an impregnation-drived catalyst.