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Supercritical CO2 1 GREEN CHEMISTRY Trường Đại học Bách khoa TP.HCM Content Supercritical CO2 Definition Properties of ScCO2 Application of ScCO2 Advantages Limitations of ScCO2 Content 1. Definition A supercritical fluid is any substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist 1. Definition 1. Definition 1. Definition CO2 critical temperature (31.1 °C) critical pressure (72.9 atm/7.39 MPa) 2. Properties of ScCO2 very sensitive to small changes in temperature and pressure in the vicinity of the critical point Properties midway between a gas and a liquid The properties of SCFs vary over a wide range depending on the temperature and pressure But intermediate of gases and liquids. Heat transfer characteristics of supercritical CO2 [...]... the supercritical fluid is possible - No toxic solvents used - Less by-products - Significant smaller reactor volumes compared to batch processes give equivalent productivity 3 Advantages 3.6 INEXPENSIVE FLUIDS - Carbon dioxide and water are the most commonly used supercritical fluids, being used for decaffeination and power generation, respectively 3 Advantages 3.7.environmenttally compatible - Supercritical. .. state > supercritical state > liquid state Diffusivity related to mass transfer directly proportional to convective heat dissipation The decrease in viscosity upon expansion directly correlates with enhanced diffusivity diffusion-controlled reaction rates Diffusivity The diffusion coefficient generally increases with temperature at constant pressure Self-diffusivity of CO2 Interfacial Tension supercritical. .. Solubility of naphthalene in supercritical CO2 Solubility Easily soluble • esters, alcohols • aldehydes, ketones • volatile oils • aromas • mono- and sesquiterpenes Reduced solubility • edible oil from oilseeds • waxes • polyphenols Unsoluble • sugars • fruit acids • starch • proteins • mineral salts • glycosides Modifiers (organic solvents) added to regulate solubility 3 Advantages Supercritical CO2 is... flammability low cost One of the main differences between supercritical fluids and conventional solvents is compressibility 2 Properties of ScCO2 SCF Symbol Tc (C) pc (MPa) MW m (D)a Ammonia NH3 132.4 11.32 0.235 Carbon dioxide CO2 31.1 7.38 44.01 0 Water H2O 374.0 22.06 0.322 Benzene C6H6 289.5 4.92 0.300 Ethene C2H4 9.2 5.04 0.214 Selected inorganic supercritical fluids Ethane C2H6 32 2 4.87 0.207 dc (g . Supercritical CO2 1 GREEN CHEMISTRY Trường Đại học Bách khoa TP.HCM Content Supercritical CO2 Definition Properties. transfer characteristics of supercritical CO2 low toxicity non flammability low cost One of the main differences between supercritical fluids and