AZD – Azeotropic and Zeotropic Data in Non-Electrolyte Mixtures

The AZD data bank contains experimental azeotropic and zeotropic information for a very large number of binary and multicomponent mixtures. This information is of foremost importance for the design of thermal separation processes including the liquid and vapor phase. Besides the fact that knowledge about azeotropic behavior and the composition of azeotropic mixtures as function of temperature and pressure has to be known, these data also present a very vital test for the thermodynamic models and parameters used for process simulation. If azeotropic behavior is not reproduced by the thermo-package or azeotropic points are falsely predicted, simulation results will in most cases be totally unrealistic. Often a less accurate description of the VLE behavior is accepted in order to reproduce the important azeotropic behavior (ACT) and the behavior at infinite dilution with high precision.

Azeotropic points with entrainers are often used to break an azeotrope between the key components or to simplify their separation (azeotropic distillation). DDB-AZD is therefore of great importance in process synthesis for the selection of potential entrainers and should be licensed together with the DDBSP-Synthesis package (in case of extractive distillation, the most important information is found in DDB-ACT).

Details About Data Types

The data bank contains (2017-02-17) 57312 data points for 2398 components and 24425 mixtures (22436 binary, 1833 ternary, and 155 quaternary systems) from 8373 different sources.

14849 mixtures are reported to be zeotropic (no azeotrope at given conditions has been observed) and 10088 mixtures are reported to be zeotropic. The sum (14849+10088=24937) exceeds the total number of mixtures (24425) because of azeotropes vanishing at some conditions and therefore both zeotropy and azeotropy has been found.

The following table gives an detailed overview about the data types stored in the azeotropic data bank. The table is sorted by the number of mixtures/systems for which data are stored.

14485 29083 zeotropic
7857 19209 homogeneous pressure maximum
1049 3024 heterogeneous pressure maximum
810 1923 homogeneous pressure minimum
521 2443 zeotropic supercritical
249 457 pressure maximum
145 215 unspecified azeotrope
87 131 zeotropic miscibility gap
67 290 homogeneous pressure maximum miscibility gap
66 119 homogeneous saddle
17 23 homogeneous pressure maximum supercritical
15 140 homogeneous pressure minimum supercritical
14 29 pressure maximum miscibility gap
12 18 homogeneous
10 45 homogeneous pressure minimum double azeotrope
10 44 homogeneous pressure maximum double azeotrope
9 14 heterogeneous
6 11 zeotropic miscibility gap supercritical
5 27 homogeneous pressure minimum miscibility gap
4 11 pressure minimum
4 6 zeotropic separation factor ~1.0
4 5 heterogeneous saddle
3 11 separation factor ~1.0
3 5 saddle
2 4 pressure maximum supercritical
2 4 homogeneous separation factor ~1.0
2 2 heterogeneous pressure maximum supercritical
1 4 zeotropic supercritical 3 liquid phases
1 3 homogeneous pressure minimum double azeotrope miscibility gap
1 2 pressure maximum double azeotrope
1 2 pressure minimum double azeotrope
1 2 homogeneous saddle miscibility gap
1 1 homogeneous double azeotrope
1 1 saddle miscibility gap
1 1 homogeneous supercritical
1 1 saddle supercritical
1 1 saddle miscibility gap supercritical
1 1 heterogeneous pressure maximum 3 liquid phases


  • If homogeneous azeotrope is stated and in addition miscibility gap or supercritical condition the azeotrope is outside the miscibility gap and below the critical point of the mixture. The miscibility gap is at another composition of the mixture - the same statement is valid for supercritical condition.
  • Several descriptions are not complete (like "Unspecified azeotrope"). This is caused by incomplete information given in the original papers.
  • Pressure maximum/temperature minimum/positive azeotropes are much more common than pressure minimum/temperature maximum/negative azeotropes.

34474 of the 57312 (60%) data points have been published in a book of Prof. Gmehling in 2004.


Data Tables, Monographies

2004    Azeotropic Data. Part 1 - 3    Gmehling J., Menke J., Krafczyk J., Fischer K.    Monograph, 9.6, 6, 1-1992 (2004)
1994    Azeotropic Data. Part 1 + 2    Gmehling J., Menke J., Krafczyk J., Fischer K.    Monograph, 9.6, 6, 1-1729 (1994)

Selected Scientific Papers

2001    Comments on "Optimization of a Wastewater System Containing the Ternary Homogeneous Azeotropic System Ethyl Acetate-Ethanol-Water    Gmehling J., Steinigeweg S., Poepken T.    Journal    Ind.Eng.Chem.Res., 40, 1, 492 493 (2001)
2001    Classification of Homogeneous Binary Azeotropes    Shulgin I., Fischer K., Noll O., Gmehling J.    Journal    Ind.Eng.Chem.Res., 40, 12, 2742 2747 (2001)
1996    Azeotropic Data for Binary and Ternary Systems at Moderate Pressures    Gmehling J., Boelts R.    Journal    J.Chem.Eng.Data, 41, 2, 202 209 (1996)
1995    A data bank for azeotropic data - status and applications    Gmehling J., Menke J., Krafczyk J., Fischer K.    Journal    Fluid Phase Equilib., 103, 6, 51 76 (1995)

Selected Scientific Papers (Experimental Data)

2008    Vapour-liquid equilibria, azeotropic data, excess enthalpies, activity coefficients at infinite dilution and solid-liquid equilibria for binary alcohol-ketone systems    Abbas R., Gmehling J.    Journal    Fluid Phase Equilib., 267, 2, 119 126 (2008)
2006    Azeotropic and Heats of Mixing Data for Several Binary Organic Systems containing 1-Methoxy-2-propanol and 2-Butoxy Ethanol    Negadi L., Gmehling J.    Journal    J.Chem.Eng.Data, 51, 3, 1122 1125 (2006)
2005    Activity Coefficient at Infinite Dilution, Azeotropic Data, Excess Enthalpies and Solid-Liquid-Equilibria for Binary Systems of Alkanes and Aromatics with Esters    Collinet E., Gmehling J.    Journal    Fluid Phase Equilib., 230, 1-2, 131-142 (2005)
2004    Vapor-Liquid-Liquid Equilibria, Azeotropic, and Excess Enthalpy Data for the Binary System n-Undecane + Propionamide and Pure-Component Vapor Pressure and Density Data for Propionamide    Horstmann S., Fischer K., Gmehling J.    Journal    J.Chem.Eng.Data, 49, 6, 1494 1498 (2004)
2003    Azeotropic and solid - liquid equilibria data for several binary organic systems containing one acetal compound    Teodorescu M., Wilken M., Wittig R., Gmehling J.    Journal    Fluid Phase Equilib., 204, 6, 267 280 (2003)
2001    Azeotropic and heats of mixing data for various binary systems with diethoxymethane    Constantinescu D., Wittig R., Gmehling J.    Journal    Fluid Phase Equilib., 191, 10, 99 109 (2001)
1998    Binary Azeotropic Data at Different Pressures for Systems with 2-Etoxyethanol, 2-Methyl-1-butanol, and Dimethyl Carbonate. 2.    Li J., Gmehling J.    Journal    J.Chem.Eng.Data, 43, 2, 230 232 (1998)