高压状态下的气体具有溶剂的性质,应用此性质导致许多前所未有的物质分离方法。接近临界温度的压缩气体(在50—300巴压力下)的密度,对气态相有较高的溶解能力,因此用其作溶剂是很有意义的。超临界气体萃取是传统的萃取方法,而萃取剂向低温和高压发展的结果。萃取剂进行萃取分离时必须高于其自身的临界温度和临界压力, Gases in high pressure have solvent properties, and the use of this property results in many of the unprecedented material separation methods. The density of the compressed gas (at a pressure of 50-300 bar) close to the critical temperature has a relatively high capacity to dissolve the gaseous phase and therefore makes sense as a solvent. Supercritical gas extraction is the result of traditional extraction methods, while the extractant develops toward low temperatures and pressures. Extractant extraction and separation must be higher than its own critical temperature and critical pressure,