Selective oxidation in supercritical (compressed) carbon dioxide

Supercritical carbon dioxide(SCCO2, T-c = 304K, P-c = 7.38MPa) has been exploited as a reaction medium for catalysis due to its potential advantages such as stability, safety, noninflammability, nontoxicity, low viscosity, high compressibility and high miscibility with many reaction gases, which makes SCCO2 very attractive for processes involving gaseous reactions that often suffer from mass transport limitations. As environmentally benign and economical solvents, supercritical carbon dioxide is properly the solvent that can not be oxidized to other by-products in oxidation reactions. By comparison with traditional organic solvent, the advantages and effects of supercritical carbon dioxide as a solvent of oxidation reaction are extensively described in the literature. The recent developments in selective catalytic oxidation are reviewed in this paper and particular attention is devoted to the selective oxidation of alcohols, ketones, alkanes, alkenes etc. by molecular oxygen as a terminal oxidant.