US 4,067,921 AGranted

Primary adjunct, continuous diene process

AssigneeThe Dow Chemical Company

InventorGunnar I. Helberg

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Abstract

C.sub.n dienes are efficiently separated and produced from a C.sub.n hydrocarbon feed stream, wherein n is 4-8. For example, 1,2- and 1,3-butadienes are separated and produced from a C.sub.4 hydrocarbon feed stream comprising C.sub.4 alkynes, n- and isobutenes, n- and isobutanes and 1,2- and 1,3-butadienes by sequentially: A. hydrogenating the C.sub.4 alkynes and removing any heavy residue produced thereby; B. separating the 1,2- and 1,3-butadienes into a first stream and the remaining C.sub.4 hydrocarbons into a second stream; C. removing first the isobutene and second the n- and isobutanes from the second stream; and D. converting the remaining alkenes of the second stream to 1,2- and 1,3-butadienes and then recycling said butadienes to the first stream of (b). This process affords greater product flexibility with less physical plant than that afforded by conventional processes.

Claims10

Dependent claims

A process for separating and producing C.sub.n dienes from a C.sub.n hydrocarbon feed stream comprising C.sub.n alkynes, C.sub.n n- and isoalkenes, C.sub.n n- and isoalkanes and C.sub.n dienes, wherein n is between 4 and 8 inclusive, the process comprising:

a. hydrogenating the C.sub.n hydrocarbon feed stream to produce a substantially C.sub.n alkyne-free stream comprising C.sub.n n- and isoalkenes, C.sub.n n- and isoalkanes, C.sub.n dienes and heavy residues;
b. removing the heavy residues from the C.sub.n alkyne-free stream to produce a purified C.sub.n stream;
c. separating the purified C.sub.n stream in a first separation zone to produce an extract stream comprising the C.sub.n dienes and a raffinate stream comprising the C.sub.n n- and isoalkenes and the C.sub.n n- and isoalkanes;
d. removing the C.sub.n isoalkenes from the raffinate stream and passing a remaining raffinate stream comprising C.sub.n n-alkenes and isoalkanes to a second separation zone;
e. separating the remaining raffinate stream in the second separation zone to produce a C.sub.n alkane stream comprising C.sub.n n- and isoalkanes and a C.sub.n alkene stream comprising C.sub.n n-alkenes;
and
f. converting the C.sub.n alkene stream into a C.sub.n diene stream and recycling said C.sub.n stream to the first separation zone.

4 more elements

Dependencies are inferred from the claim text.