In this study, we carried out a para-xylene crystallization experiment at constant temperature and concentration levels. Throughout the process, the kinetics of nucleation, growth, breakage, and aggregation of para-xylene particles were measured and built using a morphological approach. An additional a three-stage continuous suspension crystallization separation experiment was carried out, the process for which was simulated using the population balance model based on correlated kinetic equations. The population balance equation was solved using an extended moment of classes algorithm, and the solving process was implemented in MATLAB. In this case, the predicted particle size distribution of the products matched well with the experiment. In order to provide references for the optimization of the industrial para-xylene crystallization process, a three-stage suspension crystallization separation experiment was designed and conducted, in which each crystallizer had a distinct operating temperature and mean residence time. The effects of operating parameters on the final product were investigated further. The proposed models and algorithms can also be applied in other cases and provide an alternative approach for optimizing continuous crystallization processes.

A multi-stage crystallization separation process operated under three-phase conditions was proposed, which has a yield of more than 80% and purity in excess of 99.5% for p-xylene purified from a practical xylene mixture.

At a pressure of 101.33 kPa, isobaric vapor−liquid equilibrium data for binary mixtures of propylene carbonate with para-xylene, ortho-xylene, meta-xylene, and ethylbenzene were obtained. Via a modified Othmer still apparatus and gas chromatography, the fractions of the vapor and liquid phases at equilibrium were measured. The experimental findings were fitted with the Wilson, NRTL, and UNIQUAC activity coefficient models, and the binary parameters of these models were calculated. The fitted models predicted the vapor−liquid equilibrium, and the calculated values agreed well with the experimental results. The Wisniak L-W and van Ness methods were used to authenticate the thermodynamic consistency of the equilibrium data.