Vapor-liquid equilibria near critical point and critical points for the CO2+1-butanol and CO2+2-butanol systems at temperatures from 324 to 432 K

An apparatus based on the static-analytic method to perform fast determinations of vapor-liquid equilibria (VLE) and critical pressures for mixtures up to 60 MPa and 523 K has been used. Vapor-liquid equilibria near critical points and critical points of the following mixtures: carbon dioxide+1-butanol at (324.16, 333.58, 355.38, 392.72, and 426.95 K) up to 17 MPa and carbon dioxide + 2-butanol at (335.14, 348.77, 374.10, 402.47 and 431.73 K) up to 14.5 MPa are reported here over the range of compositions near critical points. The experimental data are represented using the Patel-Teja equation of state (EoS) with new Wong-Sandler type mixing rules. For the carbon dioxide + I-butanol mixtures, we found that date reported by Silva-Oliver and Galicia-Luna [submitted to J. Chem. Eng. Data], and our VLE date near critical points are in good agreement with those reported by Jennings and Teja [J. Chem, Eng. Data 3 (1991) 303]. In this work to predict the VLE near critical points for the carbon dioxide + 1-butanol mixtures was necessary to fit the parameters for NRTL model at each temperature. For the carbon dioxide + 2-butanol mixtures, our experimental data are well represented by the model using only one set of parameters, and critical points reported in this work are compared with those published by Stevens et al. [Fluid Phase Equilibria 138 (1997) 159] and are in good agreement. (C) 2001 Elsevier Science B.V. All rights reserved.