Processes in supercritical carbon dioxide

A cyclic adsorption process for citrus oil processing in supercritical carbon dioxide (SC-C02) was studied with silica gel adsorbent. Based on the adsorption equilibrium properties, where adsorbed amounts decreased with the increase in the solvent density and oxygenated compounds were selectively adsorbed on silica gel, a continuous cyclic operation between the adsorption step at 8.8 MPa and 313 K, and the desorption step at 19.4 MPa and 313 K was demonstrated Highly concentrated fraction of oxygenated com pounds was continuously obtained for the desorption and blowdown step. The proposed system showed the feasibility of the continuous operation for citrus oil processing. 

Figure 5 Configuration of a cyclic operation with two beds for the citrus oil processing in supercritical carbon dioxide.

Wai, C.M. Metal Processing in Supercritical Carbon Dioxide in Supercritical... 

The separation of the products from the IL catalytic mixture can be performed in various cases by simple decanting and phase separation or by product distillation. In this respect, a continuous-flow process using toluene as extractant has been appHed for the selective Pd-catalyzed dimerization of methyl acrylate in ILs [136]. However, in cases where the products are retained in the IL phase, extraction with supercritical carbon dioxide can be used instead of classical liquid-liquid extractions that necessitate the use of organic solvents, which may result in cross-contamination of products. This process was successfully used in catalyst recycling and product separation for the hydroformylation of olefins employing a continuous-flow process in supercritical carbon dioxide-IL mixtures [137]. Similarly, free and immobilized Candida antarctica lipase B dispersed in ILs were used as catalyst for the continuous kinetic resolution of rac-l-phenylethanol in supercritical carbon dioxide at 120°C and 150°C and 10 Mpa with excellent catalytic activity, enzyme stability and enantioselectivity levels (Fig. 3.5-11). 

Woods, H.M., et al.. Materials processing in supercritical carbon dioxide surfactants, polymers and biomaterials. Journal of Materials Chemistry, 2004.14(11) p. 1663-1678. 

Sato, M., GOTO, M., Kunishima, N., Kodama, A. and Hirose, T. (1997) Pressure swing adsorption process in supercritical carbon dioxide for the fractionation of citrus oil. Proceedings of the 4th International Symposium on Supercritical Fluids - Vol. B, Tohoku University Press, Sendai, Japan, pp. 629-632. 

PMMA-T102 and PS-T102 nanohybrid systems were synthesized via pseudodispersion polymerization processes in supercritical carbon dioxide in the presence of MPS-modified Ti02 nanoparticles [181]. 

Arora, K. A., Lesser, A. J., and McCarthy, T. J. 1998. Preparation and characterization of microcellular polystyrene foams processed in supercritical carbon dioxide. Macromolecules... 

Chang, Y. W., Kim, S., Kang, S. C., and Bae, S. Y., 2011. Thermomechanical properties of ethylene-propylene-diene terpolymer/organoclay nanocomposites and foam processing in supercritical carbon dioxide. Korean Journal of Chemical Engineering 28 1779-84. 

Arora K A, Lesser A J and McCarthy T J, Compressive Behaviour of Microcellular Polystyrene Foams Processed in Supercritical Carbon Dioxide , Polym. Eng. Sci., 1998, 38, 2055). 

A Marty, S Manon, DP Ju, D Combes, J-S Condoret. The enzymic reaction-fractionation process in supercritical carbon dioxide. Ann NY Acad Sci 750 (Enzyme Eng XII), 408-411,... 

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