Artigo diagrama

J. Chem. Thermodynamics 59 (2013) 20–27

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J. Chem. Thermodynamics journal homepage: www.elsevier.com/locate/jct

Phase behaviour of the system 40 -pentyloxy-4-cyanobiphenyl + CO2
Mariëtte de Groen, Hiroyuki Matsuda 1, Thijs J.H. Vlugt, Theo W. de Loos ⇑
Engineering Thermodynamics, Process and Energy Department, Delft University of Technology, Leeghwaterstraat 44, 2628 CA Delft, The Netherlands

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Isoplethic phase diagrams were measured for the system 40 -pentyloxy-4-cyanobiphenyl + CO2 for CO2 mole fractions up to 0.72, in temperature range 280–360 K and at pressures up to 12 MPa using a synthetic method with visual observation. It is found that pure 40 -pentyloxy-4-cyanobiphenyl shows two different solid phases, a nematic liquid phase (N) and an isotropic liquid phase (I2). For the binary system, liquid–liquid demixing (I1 + I2) was found. The following phase equilibria were measured: I2 + gas M I2, N + gas M N, solid + N M N, solid + I2 M I2, N M N + I2 and N + I2 M I2. Further, points of the three-phase curves (solid + N + gas), (N + I2 + gas), (solid + N + I2), (solid + I1 + I2) and (I1 + I2 + gas) were determined experimentally. Based on these measurements a P,T-projection of the system was constructed. At 341 K, the molar Henry coefficient of the isotropic phase was determined to be 13.7 MPa. Ó 2012 Elsevier Ltd. All rights reserved.

Article history: Received 29 August 2012 Received in revised form 5 November 2012 Accepted 6 November 2012 Available online 13 December 2012 Keywords: Liquid crystal Binary phase diagram Carbon dioxide capture Phase equilibria

1. Introduction Liquid crystals were proposed recently as solvents with a solubility switch for capturing CO2 [1,2]. One of the characteristics of liquid crystals is the presence of a structured liquid phase, either nematic or smectic, which is found at temperatures between the solid and the