超临界(压缩)二氧化碳介质中的选择氧化

Selective Oxidation in Supercritical(Compressed) Carbon Dioxide

由于超临界二氧化碳(SCCO2)具有稳定、安全、不燃、清洁无毒、黏度小、扩散快、可压缩的特殊性质,使得超临界二氧化碳非常适合作为催化反应的绿色溶剂。除此之外,多种气体在超临界二氧化碳中的溶解度很高,这对于那些受传质阻碍和易引起安全隐患的气相反应来说,使用SCCO2作为替代的反应溶剂具有重要的价值。值得指出的是:如果选择超临界二氧化碳作为氧化反应的溶剂,其自身不会发生反应而产生副产物,从而容易得到清洁的产物。本文主要讨论了超临界二氧化碳作为反应介质对醇、烯烃和烷烃等选择氧化反应的影响,通过与传统溶剂比较可以看出超临界二氧化碳作为氧化反应溶剂的优势,对近几年来以分子氧为氧化剂,以超临界二氧化碳为介质的催化选择氧化的反应体系做了综述,并对未来的发展提出了展望。

Supereritical carbon dioxide（SCCO2, Tc = 304K, Pc = 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 SCCO： 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.