Carbon Dioxide as a Benign Solvent for Homogeneous Catalyst Recovery and Recycle

Carbon dioxide;Catalyst recovery;Catalyst recycle;Homogeneous catalysis

Jones, Rebecca S. ; Chemical Engineering

University:Georgia Institute of Technology

Department:Chemical Engineering

关键词: Carbon dioxide;    Catalyst recovery;    Catalyst recycle;    Homogeneous catalysis;   

Others  :  https://smartech.gatech.edu/bitstream/1853/11641/1/Jones_Rebecca_S_0508_PhD.pdf

美国|英语

来源: SMARTech Repository

【 摘 要 】

We have successfully investigated the use of CO2 as a miscibility switch to create an environment in which we can run a homogeneously catalyzed reaction while maintaining a heterogeneous separation.We explored the use of this technique with fluorous biphasic systems, a fluorous solid support, and aqueous biphasic systems.In the case of the fluorous systems, CO2 was added to induce solubility of the fluorous catalyst.When the reaction was completed, CO2 was vented and the system returned to a biphasic state, making the separation easy.For the aqueous biphasic systems, the organic phase is chosen such that it is fully miscible with water at ambient conditions.Examples include acetonitrile, THF, and dioxane.The addition of CO2 reduces the polarity of the solvent and causes a phase split.The recovery of the water-soluble catalyst is once again heterogeneous.The application to aqueous biphasic systems is the most exciting studied.Aqueous biphasic systems are used industrially in the hydroformylation of propylene.With our technique, these systems can be extended to more hydrophobic substrates.We have shown a rate increase of 65 fold and 99% product recovery at modest pressures for the hydroformylation of 1-octene.These aqueous biphasic systems also show much promise in the arena of enzyme catalyzed reactions.We can create an environment in which the enzyme kinetics will no longer be mass transfer limited.