High Pressure Physical Solubility of Carbon Dioxide (Co 2 ) in Mixed Polyethylene Glycol Dimethyl Ethers (Genosorb 1753) Aravind V. Rayer, Amr Henni* and Paitoon Tontiwachwuthikul International Testing Center for CO 2 Capture, Faculty of Engineering and Applied Science, University of Regina, Saskatchewan, Canada, S4S 0A2 Solubility of carbon dioxide in a mixture of polyethylene glycol dimethyl ethers (Genosorb 1753) was determined at 298.15, 313.15, 323.15 and 333.15 K at pressures up to 7940 kPa. The obtained solubility data are compared with those of CO 2 in other physical solvents. The results were correlated with the Peng–Robinson (Peng and Robinson, Ind. Eng. Chem. Fundam. 15, 59–64 1976) equation of state, and the interaction parameters are reported. Data at 323.15 K were predicted. Henry’s Law constants were obtained from the data and the excess properties (excess Gibbs free energy, excess entropy and excess enthalpy) of the liquid mixture over the full range of composition were predicted at each temperature using the NRTL activity coefficient model. Enthalpy of solution and the enthalpy of mixing were determined at infinite dilution. In addition, the heats of absorption were determined using Clausius–Clapeyron equation. La solubilit´ e du dioxyde de carbone (CO 2 ) dans un m´ elange de poly´ ethyl` ene glycol dim´ ethyl ´ ethers (Genosorb 1753) a ´ et´ e d´ etermin´ ee ` a 298.15, 313.15, 323.15 et 333.15 K ` a des pressions allant jusqu’` a 7940 kPa. Les donn´ ees de solubilit´ e obtenues sont compar´ ees avec celles de CO 2 dans d’autres solvants physiques. Les r´ esultats ont ´ et´ e corr´ el´ es avec l’´ equation d’´ etat de Peng–Robinson (Peng and Robinson, Ind. Eng. Chem. Fundam. 15, 59–64 1976) et les param` etres d’interaction sont pr´ esent´ es. La solubilit´ e` a 323.15 K a ´ et´ e pr´ edite. Les constantes de la loi d’Henry ont ´ et´ e obtenues ` a partir des donn´ ees. Les propri´ et´ es en exc` es (l’´ energie libre de Gibbs d’exc` es, l’entropie et l’enthalpie d’exc` es) du m´ elange liquide sur toute la gamme de composition a ont ´ et´ e pr´ edites ` a chaque temp´ erature en utilisant le mod` ele NRTL. L’enthalpie de solution et l’enthalpie de m´ elange ont ´ et´ e d´ etermin´ ees dilution infinie. Finalement, les chaleurs d’absorption ont ´ et´ e d´ etermin´ ees en utilisant l’´ equation de Clausius–Clapeyron. Keywords: carbon dioxide, solubility, Genosorb 1753, polyethylene glycol dimethyl ethers, equation of state, Henry’s law constants, excess properties, heat of mixing, heat of solution, heat of absorption INTRODUCTION S elexol TM process, a mixture of polyethylene glycol dimethyl ethers, was patented by Allied Chemical Corporation in the late 1960s and later purchased by Norton in 1982. Union Carbide bought it in 1990, and finally acquired by Dow Chemi- cal Co. (Michigan, USA) in 2001. The absorption liquid used in the Selexol process is similar to Genosorb 1753 (i.e. a mixture of polyethylene glycol dimethyl ethers [CH 3 O (CH 2 CH 2 O) n CH 3 ] with n, for Genosorb 1753, mainly between 4 and 10, and between 3 and 11 for dimethyl ethers of polyethylene glycol (Schmidt and Mather, 2001). It is used as a physical absorption medium in acid gas removal, waste air treating processes and to clean synthesis gases (Clare and Valentine, 1975; Astarita et al., 1983; Kohl and Riesenfeld, 1985). They are characterised by low vapour pres- sure, miscibility with water and high viscosities. Most have a low enthalpy of vapourisation and therefore a lower desorption energy consumption. Physical properties of Genosorb 1753 were reported by Li et al. (2007). The absorptive capacity of Selexol is high for hydrogen sulphide (H 2 S), mercaptans (R-SH) and other sulphur containing com- pounds (CS 2 , COS) (Schmidt and Mather, 2001). Being a physical solvent, Selexol needs very little energy for regeneration. Because of small losses in vapourisation, foaming and degradation, ∗ Author to whom correspondence may be addressed. E-mail address: amr.henni@uregina.ca Can. J. Chem. Eng. 90:576–583, 2012 © 2011 Canadian Society for Chemical Engineering DOI 10.1002/cjce.20615 Published online 20 July 2011 in Wiley Online Library (wileyonlinelibrary.com). | 576 | THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING | | VOLUME 90, JUNE 2012 |