Noura Dawass

6.3. R ESULTS AND DISCUSSION 6 125 Figure 6.4: Absorption isotherm of CO 2 in MEG at T =373.15 K. Open symbols represent experi- mental data of this work, from Jou et al. [186] and from Galvao et al. [225] . Closed symbols are MC simulations results, details are provided in sectio n 6.2. where P 2 and x 2 are the partial pressure and mole fraction of solute 2, respec- tively. f 2 is the fugacity of the solute. With these experimental values, the Henry coefficient is defined as the partial pressure of CO 2 in bar divided by the molar fraction of CO 2 inMEG. InMC simulations, Henry coefficients H 21 are computed from the excess chemical potential of the solute µ ex 2 [227] , H 21 = lim x 2 → 0 k B T ρ 1 exp · µ ex 2 k B T ¸ (6.5) In Table 6.3, Henry coefficients of CO 2 in MEG H CO 2 ,MEG computed using MC simulations are reported at different temperatures and compared to Henry coef- ficients fromexperiments. Bothmethods demonstrate that the value of H CO 2 ,MEG increases with temperature. The maximum difference between experimental and computed Henry coefficients is 30%. The difference consistently decreases with increasing temperature to reach 13% at T = 373.15 K. Predictions from MC simulations are satisfactory considering that the force fields and the mixing rules used for MEG and CO 2 were not modified. The Henry coefficients reported in Ta- ble 6.3 indicate that pure MEG would not be a good absorbent for CO 2 . In a study of Ramdin et al. [228] , Henry coefficients at T = 333 K of CO 2 in selexol and the