ABSTRACT
I. INTRODUCTION Over the past century, scientists have developed considerable interest in liquid and supercritical CO2. In part, this interest has been sparked by environmental concerns involving the emission of volatile organic compounds (VOCs), the use of chlorofluorocarbons (CFCs) in polymer manufacturing and coating industries, and the enormous amounts of water used in numerous industrial processes. The use of liquid and supercritical CO2 (scCO2) as an alternative solvent choice is attractive because of the unique properties related to solvent strength. The solvent power of these fluids can often approach, and occasionally exceed, those of organic solvents without placing the environment at risk. An example where this idea has been employed is in the coffee industry. Supercritical CO2 is used in the decaffeination process of coffee where dichloromethane was previously used [1,2]. In addition to the pollution prevention opportunities provided through the utilization of CO2, increased energy efficiency is an important opportunity associated with CO2 use. Because CO2 has a very low heat of vaporization relative to
water and organic solvents, CO2-based processes offer the potential for significant energy savings. This would be especially true for water-intensive industries such as coatings, pulp and paper, textile dyeing, and polymer manufacturing. Although such uses of CO2 are advantageous, their full development in other industrial processes, organic synthesis, and polymerizations has not been realized. However, with increased research efforts from both academic and industrial sectors, the use of dense CO2 will show its value in the years to come.
