(Liquid + liquid) equilibrium for binary systems of N-formylmorpholine with alkanes

Abstract

(Liquid + liquid) equilibrium (LLE) data were determined for four binary systems containing N-formylmorpholine (NFM) and alkanes (3-methylpentane, heptane, nonane, and 2,2,4-trimethylpentane) over the temperature range from around 300 K to near 420 K using a set of newly designed equilibrium equipment. The compositions of both light and heavy phases were analyzed by gas chromatography. The mutual solubility increased as the temperature increased for all these systems. The binary (liquid + liquid) equilibrium data were correlated by the NRTL and UNIQUAC equations with temperature-dependent parameters. Both models correlate the experimental results well. Furthermore, the UNIFAC (Do) group contribution model was used to correlate and estimate the LLE data for NFM containing systems. Two methods of group division for NFM were used. NFM is treated as a single group: NFM group (method I) or divided into two groups: CHO and C 4H 8NO (method II), respectively. The group interaction parameters for CH 2–NFM, or CH 2–CHO and CH 2–C 4H 8NO were fitted from the experimental LLE data. The UNIFAC (Do) model correlates the experimental data well. In addition, in order to develop UNIFAC (Do) group contribution model to estimate the LLE data of (NFM + cycloalkane) systems, some literature LLE data were used. The group interaction parameters for c-CH 2–NFM, c-CH 2–CHO and c-CH 2–C 4H 8NO were correlated. Then these group interaction parameters were used to estimate the phase equilibrium data of binary systems in the literature by the UNIFAC (Do) model. The results showed that the estimated values are in good agreement with the literature data. In contrast, the method I is better than the method II. This shows that treating NFM as a single NFM group is more reasonable, and the fitted parameters are satisfactory for designing the aromatic recovery process with NFM as solvent.