Study on the infinite dilution activity coefficients of binary systems containing ethers, alkanols and alkanes

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The accurate design of separation process requires the knowledge of phase equilibrium behavior. The correlation or prediction of vapor-liquid equilibria (VLE) can be usually performed by using activity coefficients for liquid phase. In this study, experimental measurements of infinite dilution activity coefficients were reported for binary systems containing ethers, alkanols and alkanes. Ethers are of interest since ether, such as methyl tertial butyl ether (MTBE), has been claimed to improve the combustion efficiency of alkane. In this study, the infinite dilution activity coefficients of ethers (diethy1 ether, MTBE and diisopropy1 ether) in alkanes (octane, dodecane and hexadecane) or alkanols (octanol, decanol and dodecanol) were measured in the region of 283.15-313.15 K by using the gas stripping method.The ASOG (Analytical Solution Of Groups), which is widely applied to predict the liquid-phase activity coefficients of solutions, was applied to correlate the infinite dilution activity coefficients. In this study, the Flory-Huggins (FH) part was examined by using the infinite dilution activity coefficient data of n-alkane binary mixtures and an empirical equation is proposed to modify the number of carbons contained in the n-alkanes. The group-interaction (G) part was improved by using the number of group with the contact probability to give a good correlation for the infinite dilution activity coefficients of 1- and 2- alkanols in alkanes, and ethers in alkanes or alkanols.