Separation of a mixture of methanol and tetrahydrofuran into its

Details Separation of a mixture of methanol and tetrahydrofuran into its Separation of a mixture of methanol and tetrahydrofuran into its

1995-03-24

1996-09-24

Trinh, Ba Kim

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

549509, 568913, 568918, C07D30706, C07D30708

Patent

active

055592546

DESCRIPTION:

BRIEF SUMMARY
This is a 371 application of PCT/EP93/03184 dated Nov. 12, 1993.
The present invention relates to a process for separating a mixture of methanol and tetrahydrofuran into its constituents and to the separation of a methanol/water/tetrahydrofuran mixture into a methanol/water mixture and tetrahydrofuran.
Tetrahydrofuran (THF) is frequently used as solvent, reaction medium and starting material for various syntheses in the chemical industry, for example for preparing adhesives, special paints, coatings, fibers, in the extraction of specific active substances, for recrystallization of certain compounds or as starting material for various syntheses in a number of reactions. After these uses, the THF is often contaminated with methanol or methanol and water.
Since an azeotropic mixture cannot be completely broken down into its components in just one column with stationary operation, simple rectification, for example, of this mixture is possible only as far the azeotrope. The methanol/THF azeotrope contains 31% by weight methanol and boils at 60.7.degree. C. under atmospheric pressure (minimum azeotrope), the water/THF azeotrope contains 5.3% by weight water and boils at 64.degree. C. under atmospheric pressure, and the methanol/water/THF mixture forms two binary minimum azeotropes under atmospheric pressure and is divided by the distillation line between these azeotropes into regions I and II, see FIG. 1. In order, for example, to obtain THF from region I it is therefore necessary to cross the distillation line. It is generally known in respect of ternary mixtures that only one pure substance (not that with the intermediate boiling point) can be obtained in a single rectification step. If the individual components form azeotropes, the situation becomes complicated. This is why special distillation processes are frequently employed in industry to overcome this distillation limit either by utilizing properties intrinsic to the system, such as by changing the pressure or by adding an auxiliary such as an entrainer, see Ullmanns Encyklop adie der technischen Chemie, 4th edition, volume 2, pages 489-545.
However, all these special processes are elaborate because they require at least two or three and frequently even more columns and other equipment such as pressure elevation stages, decanters etc., and the associated connections, return lines, auxiliary workup systems (with losses thereof) etc.
EP-A 22 469 describes a process for removing methanol from mixtures of tetrahydrofuran with methanol and water. This entails at least two columns which are operated under different pressures being coupled together so that the top product of the column under the higher pressure is rich in methanol, while the bottom product of this colunm is water- and methanol-free tetrahydrofuran (page 2, line 26 to page 3, line 15).
It is an object of the present invention constituents and methanol/water mixture and THF and weight simply and without great losses.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a ternary diagram of methanol/water/THF.
FIG. 2 depicts a batchwise process for removing methanol or methanol and water from THF by pervaporation.
We have found that this object is achieved by carrying out the separations by pervaporation, with the separations taking place in the liquid or gas phase by means of an organophilic/hydrophilic membrane, for example a plasma polymerization membrane.
Further features of the process according to the invention are defined in the independent claims.
These are, on the one hand, the separation of mixtures composed of methanol or methanol/water and aliphatic and/or aromatic ethers of the formula I branched C.sub.1 -C.sub.6 -alkyl,
C.sub.2 -C.sub.6 -alkenyl,
C.sub.6 -C.sub.12-aryl, alkoxy groups with 1-4 carbons, wherein the separation is carried out by pervaporation using an organophilic/hydrophilic membrane, and, on the other hand, the separation of mixtures composed of methanol and cyclic ethers of the formula II or methanol/water and cyclic ethers of the formula II ##STR1## where R.sup.3 is
C.sub.

REFERENCES:
patent: 4798674 (1989-01-01), Pasternak et al.
patent: 5207909 (1993-05-01), Abeles
patent: 5248427 (1993-09-01), Spiske et al.
patent: 5360923 (1994-11-01), Nickel et al.

Affiliated with

Also associated with

Rating

Separation of a mixture of methanol and tetrahydrofuran into its does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Separation of a mixture of methanol and tetrahydrofuran into its, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Separation of a mixture of methanol and tetrahydrofuran into its will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1929638