Integrated Process For Normal Paraffin Alkylation (UOP)

CATEGORY: PARAFFIN ALKYLATION
Integrated Process For Normal Paraffin Alkylation (UOP)
United States Patent Application 20160168053
Kalnes; Tom N. ;   et al.   June 16, 2016
Applicant: UOP
Abstract
An integrated alkylation and disproportionation process and apparatus are described. n-C.sub.4 and n-C.sub.5 are routed to a disproportionation reaction zone for conversion to iso-C.sub.4 and C.sub.6+ isoparaffin-rich product. The iso-C.sub.4 is routed to an alkylation reaction zone and reacted with refinery propylene and butenes to produce alkylate product. The C.sub.6+ isoparaffin-rich product and alkylate product are recovered. Unconverted iso-C.sub.4 and/or olefins are recycled to the alkylation reaction zone, and unconverted n-C.sub.4 and n-C.sub.5 are recycled to the disproportionation reaction zone.
BACKGROUND OF THE INVENTION
[0001] The use of catalytic alkylation processes to produce branched hydrocarbons having properties that are suitable for use as gasoline blending components is well known in the art. Generally, the alkylation of olefins, such as butenes, by isoparaffins, such as isobutane, is accomplished by contacting the reactants with an acid catalyst to form a reaction mixture, settling said mixture to separate the catalyst from the hydrocarbons, and further separating the hydrocarbons, for example, by fractionation, to recover the alkylation reaction product. Normally, the alkylation reaction product is referred to as "alkylate", and preferably contains hydrocarbons having to 7-9 carbon atoms. In order to have the highest quality gasoline blending stock, it is preferred that hydrocarbons formed in the alkylation process be highly branched.
[0002] Due to the increased use of shale crude and tar sands, refiners must now accommodate a growing amount of normal paraffins, such as n-butanes and n-pentanes in the feedstock. Finally, some refineries are trying to manage an increasing amount of light olefin byproducts, such as propylene, produced in existing fluid catalytic cracking (FCC) units.
[0003] There is a need for a more flexible process that can accept these feeds without requiring additional isobutane from an external source.
SUMMARY OF THE INVENTION
[0004] One aspect of the invention is a process for normal paraffin alkylation. In one embodiment, the process includes introducing a feed comprising n-C.sub.4 and n-C.sub.5 paraffins to a disproportionation reaction zone in the presence of a disproportionation catalyst under disproportionation conditions to form a disproportionation mixture comprising iso-C.sub.4 and C.sub.6+ disproportionation products and unreacted n-C.sub.4 and n-C.sub.5 paraffins. The disproportionation mixture is separated in the disproportionation separation zone into at least an iso-C.sub.4-rich stream, a C.sub.6+ isoparaffin-rich stream, and a stream rich in unreacted n-C.sub.4 and n-C.sub.5 paraffins. The iso-C.sub.4-rich stream and an olefin feed stream comprising at least one of ethylene, propylene, and butenes are introduced into an alkylation reaction zone in the presence of an alkylation catalyst under alkylation conditions to produce an alkylation mixture comprising alkylate and unreacted iso-C.sub.4 paraffins. The alkylation mixture is separated in an alkylation separation zone into at least an alkylate-rich stream, and a stream rich in unreacted iso-C.sub.4 paraffins. The stream rich in unreacted n-C.sub.4 and n-C.sub.5 paraffins from the disproportionation separation zone is recycled to the disproportionation reaction zone. The stream rich in unreacted iso-C.sub.4 paraffins from the alkylation separation zone is recycled to the alkylation reaction zone, and at least one of the C.sub.6+ isoparaffin-rich stream from the disproportionation separation zone and the alkylate-rich stream from the alkylation separation zone is recovered.
[0005] Another aspect of the invention is an apparatus for normal paraffin alkylation. In one embodiment, the apparatus includes a disproportionation reaction zone having an inlet and an outlet; a disproportionation separation zone having an inlet and at least one outlet, the inlet of the disproportionation separation zone being in fluid communication with the outlet of the disproportionation reaction zone, an outlet of the disproportionation separation zone being in fluid communication with the inlet of the disproportionation reaction zone; an alkylation reaction zone having at least one inlet and at least one outlet, an inlet of the alkylation reaction zone being in fluid communication with an outlet of the disproportionation separation zone; and an alkylation separation zone having an inlet and at least one outlet, the inlet of the alkylation separation zone being in fluid communication with the outlet of the alkylation reaction zone, an outlet of the alkylation separation zone being in fluid communication with the inlet of the alkylation reaction zone.
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