Supercritical CO2: a Green Solvent

Many industrial chemical reactions, extractions, chemical separations and cleaning processes involve the use of organic solvents. In addition to the handling and disposal issues associated with these operations, these solvents can pose a number of environmental concerns such as atmospheric and ground toxicity. In many cases, conventional organic solvents are regulated as volatile organic compound because of their contribution to the greenhouse effect. In addition, certain organic solvents are under restriction due to their ozone-depletion potential.

Supercritical carbon dioxide is an attractive alternative solvent in place of traditional organic solvents. Early applications of supercritical fluids include chromatography applications and extraction applications particularly caffeine extraction from tea and coffee. There have been an increasing number of commercialized and potential applications for supercritical fluids in reactions, catalysis, extractions involving natural products and pharmaceuticals, polymer production and processing, environmental and soil remediation, cleaning processes, semiconductor processing, and powder production.

This report reviews the fundamentals of supercritical CO₂ processing, current and potential applications, and patents. The technological and economic challenges involved in implementation of the technology in different applications are discussed. We also include process economic evaluation analyses of several supercritical CO₂ applications: (1) hydroformylation of octene, (2) extraction using supercritical CO₂, (3) fluoropolymer production with supercritical CO₂ as a polymerization medium, and (4) polycarbonate production with supercritical CO₂ as a raw material.