Solubility of 2-methyl-2-propyl-1,3-propanediol and its derivatives in supercritical carbon dioxide: measurement and mathematical modeling

Abstract

The modifications for the end group of 2-methyl-2-propyl-1,3-propanediol (compound 1) were achieved by reacting with methyl oxalyl chloride and methyl malonyl chloride to generate two new CO2-philic compounds: bis(methoxyoxalic)-2-methyl-2-propyl propylene glycol ester (compound 2) and bis(methoxymalonic)-2-methyl-2-propyl propylene glycol ester (compound 3). After that, the solubilities of these three compounds were tested and compared in supercritical carbon dioxide (scCO2) within the temperature range of (313 to 353)K and in the pressure range of (9.3 to 19.0)MPa. The influence of molar mass and end group on the solubility of compound was also studied. In addition, the experimental solubility data were correlated according to Bartle, Chrastil and JCF model, and good consistencies were obtained. The average absolute relative deviation (AARD) of the measured values were (5.83, 8.98, 8.77)% when using Bartle’s method, (10.95, 7.53, 7.55)% for Chrastil’s method, and (6.89, 4.10, 4.19)% for the JCF method, respectively. It is obvious that the JCF model was proven to be the best model because it had more adjustable parameters of temperature and pressure. Finally, the partial molar volumes V¯2 for each compound in the supercritical phase were estimated in accordance with Kumar and Johnston’s theory.