Residue Curve and Bubble Temperature Distribution for Methyl Tert-Butyl Ether Chemistry at 8 atm

Methyl tert-butyl ether, also known as MTBE, is a chemical compound with molecular formula . MTBE, as well as TAME (tert-amyl butyl ether), are gasoline additives used as oxygenates to raise the octane number.
The following etherification reaction produces MTBE: isobutene + MeOH ⇌ MTBE. The reacting mixture contains -butane, an inert component, in addition to methanol (MeOH), isobutene, and MTBE. The reaction extent is limited, with an equilibrium constant taken equal to 49.0.
Vapor-liquid equilibrium is predicted using the Wilson model and the modified Raoult's law. Deviation from ideal behavior in the gas-phase is not taken into account to keep the calculation simple and to compare with available data in the literature (see [1] and [2]).
Azeotropes between MeOH and isobutene and MTBE and MeOH are reacted away. The azeotrope between MeOH and -butane is an unstable node containing 9.88 mole % MeOH. In addition, there are two reactive azeotropes: (1) close to pure MTBE, corresponding to a stable node; (2) , corresponding to a saddle point. The coordinates of the two reactive azeotropes, which contain no -butane, are
and ,
and .
These coordinates of the reactive azeotropes are in agreement with values given in the literature (see [1] and [2]).
This Demonstration shows plots of the residue curve passing through a user-specified location in the triangular diagram. The and axes of the figure are related to liquid phase compositions by
and ,
where , , and are the mole fractions of isobutene, MeOH and MTBE, respectively.
The position of pure MTBE, shown by a green dot in the diagram, is given by .
The bubble temperature distribution is superimposed on the residue curve plot and clearly indicates the nature of the azeotropes (unstable node, saddle point, or stable node). For example, a stable node corresponds to high bubble temperatures (shown in magenta in the diagram) while an unstable node will be found in the yellow regions associated with low bubble temperatures. Finally, the temperature at the locator's position and iso-temperature curves are displayed in the same diagram.


  • [Snapshot]
  • [Snapshot]
  • [Snapshot]


[1] M. H. M. Reis, L. F. S. Mascolo, and M. R. Wolf–Maciel, "Development of a Robust Algorithm to Compute Reactive Azeotropes," Brazilian Journal of Chemical Engineering, 23(3), 2006 pp. 395–403.
[2] R. W. Maier, J. F. Brennecke, and M. Stadtherr, "Reliable Computation of Reactive Azeotropes," Computers and Chemical Engineering, 24(8), 2000 pp. 1851–1858.
    • Share:

Embed Interactive Demonstration New!

Just copy and paste this snippet of JavaScript code into your website or blog to put the live Demonstration on your site. More details »

Files require Wolfram CDF Player or Mathematica.

Mathematica »
The #1 tool for creating Demonstrations
and anything technical.
Wolfram|Alpha »
Explore anything with the first
computational knowledge engine.
MathWorld »
The web's most extensive
mathematics resource.
Course Assistant Apps »
An app for every course—
right in the palm of your hand.
Wolfram Blog »
Read our views on math,
science, and technology.
Computable Document Format »
The format that makes Demonstrations
(and any information) easy to share and
interact with.
STEM Initiative »
Programs & resources for
educators, schools & students.
Computerbasedmath.org »
Join the initiative for modernizing
math education.
Step-by-Step Solutions »
Walk through homework problems one step at a time, with hints to help along the way.
Wolfram Problem Generator »
Unlimited random practice problems and answers with built-in step-by-step solutions. Practice online or make a printable study sheet.
Wolfram Language »
Knowledge-based programming for everyone.
Powered by Wolfram Mathematica © 2018 Wolfram Demonstrations Project & Contributors  |  Terms of Use  |  Privacy Policy  |  RSS Give us your feedback
Note: To run this Demonstration you need Mathematica 7+ or the free Mathematica Player 7EX
Download or upgrade to Mathematica Player 7EX
I already have Mathematica Player or Mathematica 7+