US 6,740,788 B1Granted

Integrated process for aromatics production

AssigneeUop LLC

InventorsGregory F. Maher, David A. Hamm

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Abstract

Enabling a transalkylation process to handle both C10 alkylaromatics and unextracted toluene permits the following improvements to be realized. No longer extracting toluene allows a reformate-splitter column to be eliminated. The extraction unit can be moved to the overhead of a benzene column. No longer requiring a rigorous split between C9 and C10 alkylaromatics allows a heavy aromatics column to be eliminated. Such an enabled transalkylation process requires stabilization of a transalkylation catalyst through the introduction of a metal function. A further enhancement to the flow scheme is accomplished through the elimination of clay treaters in favor of selective olefin saturation at the exits of a reforming unit and an isomerization unit. These improvements result in an aromatics complex with savings on inside battery limits curve costs and an improvement on the return on investment in such a complex.

Claims20

Dependent claims

A process for producing benzene and para-xylene from a catalytic reformate stream comprising the steps of:

(a) providing the reformate stream to a first olefin saturation zone, wherein said stream is contacted with an olefin saturation catalyst under olefin saturation conditions to produce an olefin-treated reformate stream;
(b) combining the olefin-treated reformate stream with a transalkylation product stream to form a blended stream;
(c) separating the blended stream of step (b) in a benzene-toluene fractionation zone to produce a benzene-enriched stream, a toluene-enriched stream, and a xylene-plus-enriched stream;
(d) passing the benzene-enriched stream to an extractive-distillation zone to produce a raffinate steam and a benzene product which is recovered as a product stream from said process;
(e) combining the toluene-enriched stream with a stream from a xylene column rich in C9 and C10 alkylaromatics;
(f) passing the combined streams of step (e) to a transalkylation zone, wherein said streams are contacted with a metal-stabilized transalkylation catalyst under transalkylation conditions to produce the transalkylation product stream of step (b);
(g) separating the xylene-plus-enriched stream of step (c) in a xylene fractionation zone to produce an overhead xylene stream and the stream from a xylene column rich in C9 and C10 alkylaromatics of step (e);
and
(h) passing the overhead xylene stream to a para-xylene separation zone, wherein para-xylene is concentrated into a para-xylene enriched product stream which is recovered as a product stream of said process.

6 more elements

A process for producing benzene and para-xylene from a naphtha feedstock comprising the steps of:

(a) providing the naphtha feedstock stream to a hydrotreating zone, wherein said feedstock is contacted with a hydrotreating catalyst under hydrotreating conditions to produce a hydrotreated naphtha stream;
(b) passing the hydrotreated naphtha stream to a reforming zone, wherein said hydrotreated naphtha is contacted with a reforming catalyst under reforming conditions to produce a reformed naphtha product stream comprising aromatic components and light-ended hydrocarbons;
(c) combining the reformed naphtha product stream with a transalkylation stripper-overhead-liquid stream;
(d) separating the combined streams of step (c) in a debutanizer fractionation zone wherein said fractionation zone produces a debutanizer aromatic stream and a light-ended hydrocarbon product stream which is removed from said process;
(e) combining the debulanized aromatic stream with a transalkylation stripper-bottoms stream;
(f) separating the combined streams of step (e) in a benzene-toluene fractionation zone to produce a benzene-enriched stream, a toluene-enriched stream, and a xylene-plus-enriched stream;
(g) passing the benzene-enriched stream to an extractive-distillation zone to produce a raffinate stream and a benzene product which is recovered as a product stream from said process;
(h) combining the toluene-enriched stream with a hereinafter defined stream from a xylene column rich in C9 and C10 alkylaromatics;
(i) passing the combined streams of step (h) to a transalkylation zone, wherein said streams are contacted with a metal-stabilized transalkylation catalyst under transalkylation conditions to produce a transalkylation product;
(j) separating the transalkylation product in a transalkylation stripper fractionation zone to produce the transalkylation overhead-stripper-liquid stream of step (c) and the transalkylation stripper-bottoms stream of step (e);
(k) combining the xylene-plus-enriched stream with a deheptanizer bottoms stream;
(l) separating the combined stems of (k) in a xylene fractionation zone to produce an overhead xylene stream and the stream from a xylene column rich in C9 and C10 alkylaromatics of step (h), and a bottoms stream rich in C11 alkylaromatics which is removed from said process;
(m) passing the overhead-xylene-stream to a para-xylene separation zone wherein para-xylene is concentrated into a para-xylene enriched product stream which is recovered as a product stream of said process, and a paraxylene separate zone effluent stream is produced comprising metaxylene;
(n) passing said separate zone effluent stream to a xylene isomerization zone, wherein said stream is contacted with an isomerization catalyst under isomerization conditions to produce an isomerization product;
and
(o) separating the isomerization product in a deheptanizer fractionation zone comprising at least one deheptanizer column and at least one olefin saturation zone, wherein said fractionation zone produces the deheptanizer bottoms stream of step (k).

13 more elements

A process for producing benzene and para-xylene from a naphtha feedstock using a metal stabilized transalkylation catalyst that allows processing of toluene, said process comprising the steps of:

(a) providing the naphtha feedstock stream to a hydrotreating zone, wherein said feedstock is contacted with a hydrotreating catalyst under hydrotreating conditions to produce a hydrotreated naphtha stream;
(b) passing the hydrotreated naphtha stream to a reforming zone, wherein said hydrotreated naphtha is contacted with a reforming catalyst under reforming conditions to produce a reformed naphtha product stream comprising aromatic components and light-end hydrocarbons;
(c) combining the reformed naphtha product stream with a transalkylation stripper-overhead-liquid stream and with a deheptanizer-overhead-liquid stream;
(d) separating the combined streams of step (c) in a debutanizer fractionation zone comprising at least one stabilizer column and at least one olefin saturation zone, wherein said fractionation zone produces a debutanized aromatic stream and a light-end hydrocarbon product which is removed from said process;
(e) combining the debutanized aromatic stream with a transalkylation stripper-bottoms stream;
(f) separating the combined streams of step (e) in a benzene-toluene fractionation zone to produce a benzene-enriched stream, a toluene-enriched stream, and a xylene-plus-enriched stream;
(g) passing the benzene-enriched stream to an extractive-distillation zone to produce a raffinate stream and a benzene product which is recovered as a product stream from said process;
(h) combining the toluene-enriched stream with a stream from a xylene column, rich in C9 and C10 alkylaromatics;
(i) passing the combined streams of step (h) to a transalkylation zone, wherein said streams are contacted with a metal-stabilized transalkylation catalyst under transalkylation conditions to produce a transalkylation product;
(j) separating the transalkylation product in a transalkylation stripper fractionation zone to produce the transalkylation overhead-stripper-liquid stream of step (c) and the transalkylation stripper-bottoms stream of step (e);.
(k) combining the xylene-plus-enriched stream with a deheptanizer bottoms stream;
(l) separating the combined steams of step (k) in a xylene fractionation zone to produce an overhead xylene stream, the stream from a xylene column rich in C9 and C10 alkylaromatics of step (h), and a bottoms stream rich in C11 alkylaromatics which is removed from said process;
(m) passing the overhead-xylene-stream to a para-xylene separation zone wherein paraxylene is concentrated into a para-xylene enriched product stream which is recovered as a product stream of said process, and a paraxylene separate zone effluent stream is produced comprising metaxylene;
(n) passing said separate zone effluent stream to a xylene isomerization zone, wherein said stream is contacted with an isomerization catalyst under isomerization conditions to produce an isomerization product;
and
(o) separating the isomerization product in a deheptanizer fractionation zone comprising at least one deheptanizer column and at least one olefin saturation zone, wherein said fractionation zone produces the deheptanizer-overhead-liquid stream of step (c) and the deheptanizer bottoms stream of step (k).

13 more elements

Dependencies are inferred from the claim text.