The experiments and correlations of the solubility of ethylene in toluene solvent

Polymer cyclic olefin copoly mer (COC) is produced from the reaction of attaching ethyl groups to the norbomene monomer in liquid phase. The first step of process is dissolving ethylene in a liquid phase where toluene is present as a cosolvent. Thus, the solubility of ethylene in liquid toluene is the most important factor affecting the production of COC. In this study, the solubility of ethylene in toluene was measured in the temperature range from 323.15 to 423.15 K and pressure range from 5 to 25 bar. The experiments were conducted by the method of pressure decaying with a newly designed apparatus. The experimental results show that the solubility of ethylene in toluene increases with increasing pressure but decreases with increasing temperature. The experimental solubility data were expressed in the vapor-liquid equilibrium relationship and correlated fairly well by the bubble-pressure calculation with the Peng-Robinson equation of state (PR EOS) incorporated with the van der Waals one-fluid and the Zhong-Masuoka mixing rules with the consideration of binary interaction parameters. The results showed the van der Waals (vdW-1) mixing rule is slightly better than the Z-M mixing rule for pressure correlation but the Z-M mixing rule is slightly better for vapor composition correlation. A semi-empirical solubility equation with four parameters for the present binary system was proposed in this study. This proposed model estimates the solubility easier and as accurate as the PR EOS does for the present system. (c) 2005 Elsevier B.V. All rights reserved.