Gas Expanded Liquids for Sustainable Catalysis

Carbon Dioxide Solvent Applications in a Biorefinery

“…Even with the use of solvents, CO 2 may decrease the negative impacts associated with a particular reaction by minimizing the need for hazardous solvents, decreasing the flammability envelope of a system, improving the usage of a particular feedstock, and reducing energy usage through process intensification. Comprehensive reviews for the utilization of CO 2 in reactions are available, though none are specifically geared towards biomass processing (22,(84)(85)(86)(87)90). In terms of catalysts, Seki et al (91) offer a critical review on the use of supercritical fluids for use in heterogeneous catalyst applications.…”

“…In addition to kinetics, the use of CO 2 may improve reaction selectivity and potentially allow for a given reaction to be tuned for a particular product distribution (85). Even with the use of solvents, CO 2 may decrease the negative impacts associated with a particular reaction by minimizing the need for hazardous solvents, decreasing the flammability envelope of a system, improving the usage of a particular feedstock, and reducing energy usage through process intensification.…”

“…Furthermore, gases have increased solubility in both sccCO 2 and CXL's as compared to conventional solvents leading to improved availability of gaseous reactants in the liquid phase (85,86). Other advantages of using CO 2 as a solvent for reaction mediation are that CO 2 cannot be oxidized, is generally immune to free radical chemistry, and is miscible with gases and many organic materials (87).…”

“…In terms of reagent availability, CO 2 may change the melting point properties of certain compounds thus allowing for reactions to occur at closer to ambient temperatures (i.e. liquid-liquid versus solid-liquid reactions at temperatures well below the substrate melting point) (85). CO 2 may also serve as an anti-solvent in reaction systems as illustrated by Organic Aqueous Tunable Solvents (OATS) where CO 2 facilitates solvent-catalyst separations post-reaction as with switchable solvent systems (88).…”

Pd Nanoparticles and Mixture of CO2/CO/O2 Applied in the Carbonylation of Aniline

“…and enhanced transport rates compared to organic solvents at ambient conditions. The enhanced gas solubilities in GXLs may result in reaction rates greater than those achieved in neat organic solvent or supercritical carbon dioxide (sCO2) [47]. In the case of our process, even if CO2 cannot serve as a carbonylating agent, it is…”