Catalytic hydrogenation of polycyclic aromatic hydrocarbons over palladium/γ-Al2O3 under mild conditions

As a prelude to the optimization of a continuous decontamination system, catalytic hydrogenations of selected tri-, tetra- and penta-cyclic aromatic hydrocarbon compounds over commercial alumina supported palladium were investigated under mild conditions (∼90 °C/0.42 MPa H2) and interpreted in the light of reports from the literature. Acenaphthylene, acenaphthene, anthracene, phenanthrene, chrysene and benzo[α]pyrene were hydrogenated, virtually completely, to saturated polycyclic hydrocarbon compounds with no appreciable evidence of carbon-carbon bond rearrangement during equilibration. With comparable operating conditions, triphenylene was only partially hydrogenated; the central ring remained unsaturated. The effects of reaction temperature, time of equilibration and supporting gases on hydrogenation were evaluated. Whereas near-critical CO2 had no perceptible influence on rate/course of the reaction, nitrogen decreased the reaction rate somewhat.