Selective oxidation in supercritical carbon dioxide using clean oxidants

We have systematically investigated heterogeneous catalytic oxidation of di fferent substrates in supercritical carbon dioxide (SC-CO2). Three types of catalysts, a metal complex {cis-[Fe-(dmp)(2)(H2O)(2)] (CF3SO3)(2)} (dmp = 2,9-dimethyl-1,10-phenanthroline), 0.5% platinum gamma -alumina, and 0.5% p alladium gamma -alumina, were used at a pressure of 200 bar, at temperature s from 60 to 150 degreesC: and for 3-18 h for partial oxidation of organic substrates. The metal-ore catalyst used gave as high as 3.9% conversion of cycloxene to its oxides and epoxides, with the major products being the ket one and alcohol. The oxidation of cyclohexene strongly depended on the conc entration of oxygen, whereas length of reaction (3-18 h) and temperature (6 0-150 degreesC) were shown to be less significant on the conversion and sel ectivity of the reaction. Oxidation of cyclohexene over Pd and Pt/Al2O3 cat alysts resulted in a mixture of dehydrogenation and oxygenated products.