Process for producing a branched chain olefin by isomerization a

Details Process for producing a branched chain olefin by isomerization a Process for producing a branched chain olefin by isomerization a

1995-01-04

1997-06-17

Caldarola, Glenn A.

Chemistry of hydrocarbon compounds

Adding hydrogen to unsaturated bond of hydrocarbon, i.e.,...

Hydrocarbon is contaminant in desired hydrocarbon

585257, 585260, 585261, 585262, 585616, 585627, 585629, 585630, 585631, 585654, 585656, 585734, 585738, C07C 502, C07C 508, C07C 513

Patent

active

056399260

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

This invention relates to the production of olefins and in particular to the production of branched chain olefins, particularly 2-methyl propene (iso-butene, hereinafter i-butene).
i-Butene is a valuable chemical intermediate and is in increasing demand as a reactant for the production of methyl t-butyl ether (MTBE) by reaction of i-butene with methanol. i-Butene, and other branched chain olefins, are usually produced by subjecting a suitable paraffin stream containing straight chain paraffins, for example, n-butane, to isomerisation by passage over a suitable catalyst, which is often a sodium aluminium silicate material such as Na-zeolite, to give branched chain paraffins, for example 2-methyl propane. (iso-butane, hereinafter i-butane). The resultant i-butane is then dehydrogenated to give i-butene.


DESCRIPTION OF THE PROIR ART

Also known are processes wherein straight chain paraffins, for example, n-butane, are first dehydrogenated to the corresponding olefins, for example, n-butenes, and then the olefins are subjected to isomerisation.
In the present invention, the dehydrogenation is effected by a procedure termed transhydrogenation. In a transhydrogenation process a hydrogen-donor, such as a paraffin, is catalytically dehydrogenated in the presence of a hydrogen-acceptor such as an unsaturated compound so that the latter is hydrogenated at the same time. In effect, although this may not be the actual reaction mechanism, hydrogen is transferred from the hydrogen-donor to the hydrogen-acceptor, hydrogenating the latter.
Transhydrogenation processes for the production of olefins have been described for example in U.S. Pat. No. 3,267,170 and U.S. Pat. No. 4,684,755 wherein a hydrogen-donor such as propane, n-butane, or i-butane, has been reacted over a catalyst with a mono-olefin such as ethene as a hydrogen-acceptor. In the reaction, the hydrogen-donor is dehydrogenated to the corresponding olefin while the hydrogen-acceptor is hydrogenated to the corresponding paraffin for example, ethane. It is seen that there is no net production of olefin since for each mole of olefin produced from the paraffin, one olefin molecule is consumed as the hydrogen-acceptor. Indeed there may be a net reduction in the olefin content since the aforesaid U.S. Pat. No. 3,267,170 discloses that the hydrogen-donor may be dehydrogenated further, to the corresponding diene, and/or that a mixture of the paraffin and the corresponding olefin may be dehydrogenated, by reaction with the hydrogen-acceptor olefin, to give a mixture of the olefin and diene corresponding to the paraffin. For example, it is suggested that a mixture of n-butane and butene-1 or butene-2, may be reacted with ethane as the hydrogen-acceptor olefin to give a mixture of butene-1, butene-2, and butadiene-1,3.
The use of transhydrogenation to produce 1-butene is described in EP-A-474188 where n-butenes, for example, butene-1, are transhydrogenated with i-butane to give n-butane and i-butene. That reference discloses the separation of the i-butene by reaction with methanol to form MTBE and recycle of the n-butane to the transhydrogenation step via an isomerisation unit wherein the n-butane is converted to i-butane.
In the present invention, a more highly unsaturated compound, such as a diene or acetylene, is used as the hydrogen-acceptor in place of a mono-olefin hydrogen-acceptor. This results in net olefin production.
Accordingly, a process for the production of a branched chain olefin comprises subjecting a hydrocarbon stream containing at least one straight chain paraffin having 4 or more carbon atoms to isomerisation and transhydrogenation with a stream containing at least one hydrogen-acceptor that is more highly unsaturated than a mono-olefin, thereby producing a stream containing at least one branched chain olefin product, separating said product to give a stream depleted of said product, and recycling at least part of the stream depleted of said product to before the isomerisation and transhydrogenation stages.
In the present inv

REFERENCES:
patent: 3211635 (1965-10-01), Cywinski
patent: 4546204 (1985-10-01), Parris
patent: 5160424 (1992-11-01), Le et al.

Affiliated with

Also associated with

Rating

Process for producing a branched chain olefin by isomerization a does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for producing a branched chain olefin by isomerization a, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing a branched chain olefin by isomerization a will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2159164