US Patent 7201804 Cleaning of hydrocarbon-containing materials with critical and supercritical solents

A method for cleaning materials containing solids and/or liquids is disclosed which involves contacting the materials with an extracting fluid including Xe, NH3, lower aromatics, nitrous oxide, water, CO, CO2, H2O, lower alcohols, lower alkanes, lower alkenes, or mixtures or combinations thereof under conditions of temperature and pressure sufficient to maintain the fluid at, near or above its critical point and to products derived therefrom.