Experimental PTx data have been measured
and reported for three
binary mixtures containing morpholine under 18 conditions using a
Sweitoslawski-type ebulliometer. The measured pressure (P), temperature (T), and liquid(x) composition (PTx)
data were correlated by five popular excess free-energy models using
the Gauss–Newton (GN) optimization algorithm to obtain the
vapor composition and optimized parameters simultaneously. In general,
the Margules model had been found to be the best in vapor composition
predictions. UNIFAC predictions for the activity coefficients and
vapor compositions were also made for each dataset to evaluate the
suitability of group interaction parameters published for two UNIFAC
versions. However, the results were not compatible with the predictions
by the two-parameter models. The binary mixtures studied in the present
work exhibited negative deviations from Raoult’s law with a
few exceptions. A comparison made between the measured vapor pressure
data and the available literature data for four pure components showed
good agreement. When the Tx data of methanol–morpholine mixture
at 74.26 and 101.32 kPa were compared with the published data, large
deviations were observed for the data at 101.32 kPa. Moreover, the
pair of activity coefficients at infinite dilution data for each binary
system were predicted using Margules and UNIFC models.