(180w) Phase Behavior of the System Hyperbranched Polyglycerol – Methanol – CO2

Dendritic and Hyperbranched Polymers (HBPs) are currently being considered as solvents or entrainers within the field of thermal separations [1,2]. To determine the applicability of HBPs as process solvents for CO2 removal from gas streams, the vapor-liquid equilibria of different HBP ? Co-solvent ? CO2 (Hyperbranched polyglycerol-methanol-CO2) systems are measured (compare Figure 1) and the influence of the molecular mass on the phase equilibrium is analyzed. Methanol is used as a co-solvent, in order to keep the viscosity sufficiently low. Unlike usual polymer phase equilibria, these systems show a distinct dependence of the bubble point pressure on the molar mass. These molecular structures still require adequate models to describe, extrapolate and predict their thermodynamic behavior. An attempt to model these systems was done by using the PC-SAFT EOS for branched molecules, which has been presented earlier [4]. Furthermore, the phase envelopes of the ternary system linear Polyglycerol (Mw=2800)-methanol-CO2 is determined to evaluate the influence of the branched structure on the phase behavior.

References

[1] M. Seiler, Fluid Phase Equilib. 241 (2006) 155-174.

[2] J. Rolker et al., Ind. Eng. Chem. Res. 46 (2007) 6572-6583.

[3] J. Gross, G. Sadowski, Ind. Eng. Chem. Res. 40 (2001) 1244-1260.

[4] M.K. Kozlowska et al., J. Phys. Chem. B, 113 (2009) 1022-1029.