Solvent Screening for the Supercritical Hydrogenation of Polyunsaturated Hydrocarbons Using VLE Calculations

Preliminary knowledge of VLE behavior of multiphasic reaction mixtures is required for the operation and design of chemical reactors that work with supercritical fluid as solvents. In this case, the operating parameters of a continuous fixed-bed catalytic reactor are to be optimized for the selective hydrogenation of 1,5,9-cyclododecatriene (CDT) to form the second intermediate cyclododecene (CDE). Commercial simulators (Aspen, HYSYS, PRO-II), as well as a user-written program based on high-pressure flash calculations, are tested in predictions of the phase envelope of the reaction mixture. Important binary interaction parameters (Peng−Robinson) are determined by fitting experimental and calculated data for the solubilities of CDT and CDE in supercritical CO2. Data are calculated with the user-written program, whereas experimental solubility points are obtained in quasi-binary-equilibrium runs at very low fluid flow rates. It is observed that the commercial simulators poorly predict the near-critical regi...