Phase-behavior of alkyl ketene dimmer (AKD) in supercritical carbon dioxide. The implications of using different solubility measurement methods

In this work, three different methods were used to determine the phase behavior of alkyl ketene dimer (AKD) in supercritical carbon dioxide (SC-CO2). Rough values for the total solubility of AKD in SC-CO2 were obtained. The solubility ranges from 1 to 14 mg AKD/g CO2 at temperatures from 40 to 80 °C and pressures from 10 to 30 MPa. A significant increase in solubility was observed in the region above 50 °C and 20 MPa. A region of improved solubility was found, without the presence of a cross-over pressure point.The fact that different solubility methods gave different results was discussed and the importance of data interpretation was highlighted. 1H NMR and MALDI-TOF MS analyses were utilized to chemically characterize the AKD wax. Its special behavior and the influence of data interpretation on the design of a RESS process were discussed.

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► Solubility values of alkyl ketene dimmer in supercritical carbon dioxide are obtained.
► Three different solubility measurement methods are used and compared.
► Data interpretation has critical implications on the design of further high-pressure processes.