Studies on Phase Equilibrium of Tertbutanol in Supercritical CO2

Vapor-liquid phase equilibrium data of tertbutanol in the SC-CO2 from 323.2 K to 353.2 K were determined by constant-volume visual method. The phase equilibrium model was established by Peng-Robinson equation of state and Vander Waals-2 mixed regulation. Model parameters were obtained by nonlinear least square method optimization calculation. Furthermore, the correlation equations of model parameters vs. temperature were obtained: k(12) = - 199. 2066 + 1. 8136T - 0. 00548T(2) + 5. 50 x 10(-6) T-3, n(12) = - 384. 5626 + 3. 4960T - 0. 01056T(2) + 1. 06 x 10(-5) T-3. Critical properties of critical pressure, critical temperature, critical molar volume and critical density were deduced. The results showed that critical temperature, critical pressure and critical compressibility factor of CO2-tertbutanol system would decrease with the increasement of critical CO2 content.