Distillation: processes – separatory – Plural distillations performed on same material – One a distillation under positive pressure or vacuum
Patent
1998-02-17
1999-11-16
Manoharan, Virginia
Distillation: processes, separatory
Plural distillations performed on same material
One a distillation under positive pressure or vacuum
203 75, 203 77, 203 78, 203 80, 203 99, 203DIG19, 203 14, 568698, 568699, 568916, 568918, B01D 300, C07C 2980, C07C 4142
Patent
active
059851007
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an improved process for separating butanol and dibutyl ether from a mixture containing water, dibutyl ether and n-butanol, 2-butanol and/or isobutanol.
Butanols are widely used in the chemical industry, and the use as solvents in coatings and as starting material for the synthesis of plasticizers are typical examples.
The large scale industrial production of butanol is carried out predominantly by hydroformylation of propene and subsequent hydrogenation to butanol, and is described, for example, in D1 (Chem. Ing. Techn., 41st year, 1969, pages 974-980, Dr. Dumbgen, Dr. Neubauer, GroBtechnische Herstellung von Oxo-Alkoholen aus Propylen in der BASF). In the process described here, it is proposed to separate butanol from mixtures which contain dibutyl ether and water by extraction with water and then to separate butanol and water by distillation (page 978, second section). However, this separation process proves to be relatively expensive where large amounts have to be separated off, since the extraction requires large amounts of water as an extracting agent, which have to be subsequently separated off again by distillation.
In the non prior published German patent application D2 (O.Z. 0050/44548, file reference P 4400837.6), a process for the preparation of n-butyraldehyde and/or n-butanol starting from 1,3-butadiene is described. There, the butanol preparation is carried out finally in stage d) of the process, an enol ether being converted in the presence of water and hydrogen (page 24, lines 8 to 34). The resulting mixture also contains dibutyl ether and water in addition to butanol and must be separated before further processing.
It is an object of the present invention to provide an improved process which permits the separation of butanol and dibutyl ether from mixtures containing butanol, dibutyl ether and water by a procedure which is simple and economical in terms of process engineering. It is a further object of the present invention to enable butanol or dibutyl ether to be isolated in high purity, the introduction of additional water being avoided.
We have found that these objects are achieved by a process for separating butanol and dibutyl ether from a mixture containing water, dibutyl ether and n-butanol, 2-butanol and/or isobutanol, wherein butanol is separated off at the bottom of this distillation column and the mixture taken off at the top of the distillation column ether is separated off at the bottom of this second distillation column and the mixture formed at the top of the second distillation column is removed, the first distillation column and at least one of the two mixtures taken off via the top of the distillation columns being subjected to phase separation, only the organic phase separated off being fed to the second distillation column in the case of phase separation downstream of the first distillation column, and separation into an aqueous and an organic phase also being effected in the case of phase separation downstream of the second distillation column, a part stream being recycled from the top or rectification section of the second distillation column to the first distillation column.
FIGS. 1 and 2 show arrangements for distillation columns suitable for carrying out the present process.
FIGS. 3 and 4 schematically set out the arrangement for the distillation in laboratory scales. FIG. 3 particularly sets forth the arrangement of the first distillation column and FIG. 4 represents an arrangement for the second distillation column.
The novel process is described in detail by way of example below with reference to FIG. 1.
A mixture which contains essentially butanol, dibutyl ether and water is fed to a distillation column (1) by means of pipe (2). Mixtures which contain from about 20 to 99, preferably from 70 to 95%, by weight of butanol, from 0.05 to 50, preferably from 0.5 to 10%, by weight of dibutyl ether and from 0.05 to 50, preferably from 1 to 20%, by weight of water are particularly suitable for the novel process. Virtually pure butanol is
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Derwent Abs.AN 70-24101R.
Aron Maik
Rust Harald
BASF - Aktiengesellschaft
Manoharan Virginia
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