Enhanced Catalyst Reactivity and Separations Using Water/Carbon Dioxide Emulsions

• Published in: Journal of the American Chemical Society Vol. 121; no. 50; pp. 11902 - 11903
• Main Authors: Jacobson, Gunilla B, Lee, C. Ted, Johnston, Keith P, Tumas, William
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 22-12-1999
• Subjects: CARBON DIOXIDE; EMULSIONS; ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; HOMOGENEOUS CATALYSIS; SEPARATION PROCESSES; SUPERCRITICAL STATE; WATER
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja993208x

The difficulty of catalyst separation and recovery continues to create economic and environmental barriers to the broader industrial application of homogeneous catalysts for chemical transformations, despite the remarkable activity and selectivity attainable through sophisticated ligand design in these systems. A number of approaches termed biphasic catalysis have been advanced where a soluble catalyst is immobilized in one liquid phase (often aqueous) and the substrates and products are isolated in a separate immiscible phase. The authors wish to report a new aqueous biphasic homogeneous catalysis system that uses only water and environmentally benign supercritical carbon dioxide (CO{sub 2}) along with water-soluble catalysts and emulsion-forming surfactants which are active at the water/CO{sub 2} (w/c) interface. After reaction, the emulsion can be broken by simply decreasing the pressure to effect product separation and catalyst recycle.