US 6,420,619 B1Granted

Cracked gas processing and conversion for propylene production

OwnerRobert J. Gartside, Gary R. Gildertinventors

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Abstract

The C3 to C6 cut from a cracking process containing propylene, butane, 1-butene, 2-butene and acetylenic and diene components including butadiene are preferentially converted to propylene. The cut is simultaneously fractionated and catalytically hydrogenated to hydrogenate the acetylenic and diene components. The fractionation and subsequent separation recovers a C4 component comprising a mixture of isobutene, 1-butene and 2-butene. This C4 component is then further simultaneously fractionated and catalytically hydrogenated and hydroisomerized to hydrogenate remaining butadiene, remove isobutene overhead and convert 1-butene to 2-butene leaving a bottoms of 2-butene. The 2-butene is then injected with ethylene and catalytically metathesized to form propylene.

Claims9

Dependent claims

A process for the preferential conversion to propylene of a C3 to C6 cut containing propylene, butane, 1-butene, 2-butene, isobutene and acetylenic and diene components including butadiene comprising the steps of:

(a) simultaneously fractionating and selectively hydrogenating said cut in the presence of an hydrogenation catalyst whereby said acetylenic and diene components including said butadiene are hydrogenated and said C3 and C4 and some of said C5 components are fractionated overhead;
(b) separating said C3 and some C5 components in said overhead from said C4 components comprising a mixture of isobutene, 1-butene and 2-butene;
(c) simultaneously fractionating and hydrogenating and hydroisomerizing said C4 components in the presence of an hydrogenating catalyst whereby said 1-butene is isomerized to 2-butene and whereby any remaining butadiene is hydrogenated and isobutene is separated overhead and 2-butene is separated as bottoms;
(d) injecting said 2-butene bottoms with ethylene and reacting said 2-butene and ethylene in the presence of a metathesis catalyst whereby a metathesis product containing propylene is formed.

1 more element

Dependencies are inferred from the claim text.