4-Formylmorpholine: Vapor-Liquid Equilibrium and Extractive Distillation Application

4-Formylmorpholine is a versatile organic compound used primarily as a solvent and in organic synthesis, particularly for the preparation of various chemical derivatives.

Vapor–Liquid Equilibrium of 4-Formylmorpholine with Toluene and Xylene

Equilibrium data are the basis for the design and computation of separating processes, such as distillation, absorption, extraction, and crystallization. An abundance of experimental data are needed for an accurate design of separation processes and facilities. 4-Formylmorpholine (NFM) is widely used in the recovery of aromatics as a solvent for its good selectivity and heat stability. To design or improve these processes, it is extremely important to determine the phase equilibrium data of systems containing 4-Formylmorpholine. However, only the vapor–liquid equilibrium (VLE) data for the benzene + NFM system at atmospheric pressure and the m-xylene + NFM system at 150 kPa were found in the literature. VLE data for toluene + NFM, o-xylene + NFM, m-xylene + NFM, and p-xylene + NFM at 101.33 kPa were measured. Binary interaction parameters (BIPs) adjusted on these four binary systems were obtained by correlating with the Wilson and NRTL equations, with which multicomponent-system VLE data can be predicted. All chemicals used in this study were supplied by Tianjin Reagent Co. except 4-Formylmorpholine, which was supplied by Shanghai Chemical Reagent Co. 4-Formylmorpholine was purified by distillation. Other liquids were subjected to no further purification. All chemicals were dried over 0.4 nm molecular sieves prior to their experimental use.[1]

Experimental VLE data for four binary systems of toluene + NFM, o-xylene + NFM, m-xylene + NFM, and p-xylene + 4-Formylmorpholine were determined at 101.33 kPa. It can be seen from the experimental VLE data of the benzene−toluene system and the boiling point of ethanol that the performance of the modified Rose−Williams still is favorable. The benzene−toluene system satisfied thermodynamic consistency as validated by using the Herington semiempirical method which indicates the equipment is reliable. Analysis of the experimental data of the four binary systems by using the Wilson and NRTL equations shows that both equations generally give satisfactory results. The VLE data of the benzene−toluene−4-Formylmorpholine ternary system were measured and predicted using the Wilson equation, which shows that BIPs adjusted on the binary system can be used for the prediction of multicomponent-system VLE.

Isobaric vapor-liquid equilibrium for 4-Formylmorpholine

4-Formylmorpholine (NFM) is an excellent extract ing agent for extractive distillation [6, 7] because of its high boiling point (513.3 K) and good thermal stability. For the development of extractive distillation process to separate the mixture of toluene-3-methylthiophene, there is a demand for the VLE data of the ternary mixture of toluene-3-methylthiophene-NFM. In recent years it has become increasingly important to determine the VLE data of new mixtures, there have been various models to estimate the VLE data of non-ideal systems, but for new systems especially in the final design stage, the essential VLE data need to be determined experimentally.[2]

Isobaric vapor-liquid equilibrium (VLE) data were measured for binary mixtures of toluene+4-Formylmorpholine, toluene+3-methylthiophene and 3-methylthiophene+4-Formylmorpholine at 101.33 kPa. The VLE data of the binary systems were found to be thermodynamically consistent. The saturated vapor pressure calculated by CSGC-PR equation of the pure component had higher accuracy than that calculated by Antoine equation. The liquid-phase activity coefficients of the binary systems were calculated by the Wilson, NRTL and UNIFAC models, and the binary interaction parameters of the three models were determined by the VLE data. The Wilson model was selected as the most suitable model to predict the VLE data of the ternary system of toluene+3-methylthiophene+Nformylmorpholine. The relative volatility between toluene and 3-methylthiophene was also calculated. Moreover, the effect of 4-Formylmorpholine as solvent was studied. When the molar ratio of solvent to feed (S/F) was 7, the relative volatility reached 1.904, which is almost twice the relative volatility without solvent. Therefore, 4-Formylmorpholine can be considered as an effective extracting agent for the separation of the close-boiling mixture of toluene+3-methylthiophene by extractive distillation.

References

[1]Huang, X., Xia, S., Ma, P., Song, S., & Ma, B. (2008). Vapor–liquid equilibrium of N-formylmorpholine with toluene and xylene at 101.33 kPa. Journal of Chemical & Engineering Data, 53(1), 252–255.

[2]Li, P., Qi, H., & Chang, H. (2012). Isobaric vapor–liquid equilibrium for toluene, 3-methylthiophene and N-formylmorpholine at 101.33 kPa. Transactions of Tianjin University, 18, 224–230.

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