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 (2014-October-15) 55620 data points for 2320 components and 24044 different mixtures (22017 binary, 1818 ternary, and 155 quaternary systems) from 9293 different sources.

14603 mixtures are reported to be zeotropic (no azeotrope at given conditions has been observed) and 9929 mixtures are reported to be azeotropic. The sum (14603+9929=24532) exceeds the total number of mixtures (24044) 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.

Systems/Mixtures Points Descriptions
14258 28192 None (zeotropic behavior)
7728 18656 Homogeneous
1042 2987 Heterogeneous pressure maximum azeotrope
802 1891 Homogeneous pressure minimum azeotrope
498 2328 None (supercritical condition)
232 430 Pressure maximum azeotrope
139 204 Unspecified type
86 130 None (with iscibility gap)
66 119 Homogeneous
65 287 Homogeneous pressure maximum azeotrope (miscibility gap)
17 22 Homogeneous pressure maximum azeotrope (supercritical condition)
15 139 Homogeneous pressure minimum azeotrope (supercritical condition)
14 29 Pressure maximum azeotrope (miscibility gap)
10 43 Homogeneous pressure maximum double azeotrope
10 44 Homogeneous pressure minimum double azeotrope
9 13 Homogeneous azeotrope
9 14 Heterogeneous azeotrope
6 11 None (miscibility gap, supercritical condition)
5 27 Homogeneous
4 5 Heterogeneous saddle azeotrope azeotrope
3 10 Pressure minimum azeotrope
3 11 Separation factor close to 1
3 5 None (separation factor close to 1)
2 2 Saddle azeotrope
2 4 Pressure maximum azeotrope (supercritical condition)
2 2 Heterogeneous pressure maximum azeotrope (supercritical condition)
2 4 None (homogeneous, separation factor close to 1)
1 1 None (Homogeneous)
1 1 Homogeneous
1 1 Saddle azeotrope (miscibility gap)
1 2 Homogeneous
1 3 Homogeneous
1 1 Saddle azeotrope (supercritical condition)
1 1 Saddle azeotrope (miscibility gap, supercritical condition)
1 1 Heterogeneous pressure maximum azeotrope (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 55620 (62 %) 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)