US2801271A - Xylene separation process - Google Patents
Xylene separation process Download PDFInfo
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- US2801271A US2801271A US216244A US21624451A US2801271A US 2801271 A US2801271 A US 2801271A US 216244 A US216244 A US 216244A US 21624451 A US21624451 A US 21624451A US 2801271 A US2801271 A US 2801271A
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- Prior art keywords
- xylene
- fraction
- isobutene
- alkylation
- para
- Prior art date
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- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 title claims description 56
- 239000008096 xylene Substances 0.000 title claims description 49
- 238000000926 separation method Methods 0.000 title description 7
- VQTUBCCKSQIDNK-UHFFFAOYSA-N Isobutene Chemical compound CC(C)=C VQTUBCCKSQIDNK-UHFFFAOYSA-N 0.000 claims description 60
- URLKBWYHVLBVBO-UHFFFAOYSA-N Para-Xylene Chemical compound CC1=CC=C(C)C=C1 URLKBWYHVLBVBO-UHFFFAOYSA-N 0.000 claims description 52
- 238000005804 alkylation reaction Methods 0.000 claims description 40
- 239000003054 catalyst Substances 0.000 claims description 32
- IVSZLXZYQVIEFR-UHFFFAOYSA-N m-xylene Chemical compound CC1=CC=CC(C)=C1 IVSZLXZYQVIEFR-UHFFFAOYSA-N 0.000 claims description 32
- 238000005336 cracking Methods 0.000 claims description 31
- 230000029936 alkylation Effects 0.000 claims description 30
- 238000000034 method Methods 0.000 claims description 21
- 150000003738 xylenes Chemical class 0.000 claims description 19
- 239000007795 chemical reaction product Substances 0.000 claims description 12
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 10
- TVMXDCGIABBOFY-UHFFFAOYSA-N octane Chemical compound CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 claims description 9
- 239000003209 petroleum derivative Substances 0.000 claims description 9
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 8
- 229910000040 hydrogen fluoride Inorganic materials 0.000 claims description 6
- 239000007788 liquid Substances 0.000 claims description 3
- 229940074411 xylene Drugs 0.000 description 31
- YNQLUTRBYVCPMQ-UHFFFAOYSA-N Ethylbenzene Chemical compound CCC1=CC=CC=C1 YNQLUTRBYVCPMQ-UHFFFAOYSA-N 0.000 description 24
- 238000004523 catalytic cracking Methods 0.000 description 13
- 239000007789 gas Substances 0.000 description 11
- 238000009835 boiling Methods 0.000 description 10
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 7
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- 239000000203 mixture Substances 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 4
- 229940078552 o-xylene Drugs 0.000 description 4
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- -1 T-BUTYL Chemical class 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 3
- 239000011324 bead Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- LTPBRCUWZOMYOC-UHFFFAOYSA-N Beryllium oxide Chemical compound O=[Be] LTPBRCUWZOMYOC-UHFFFAOYSA-N 0.000 description 2
- 238000005727 Friedel-Crafts reaction Methods 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000002152 alkylating effect Effects 0.000 description 2
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 2
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 description 2
- IAQRGUVFOMOMEM-UHFFFAOYSA-N butene Natural products CC=CC IAQRGUVFOMOMEM-UHFFFAOYSA-N 0.000 description 2
- 125000000484 butyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 2
- OCKPCBLVNKHBMX-UHFFFAOYSA-N butylbenzene Chemical compound CCCCC1=CC=CC=C1 OCKPCBLVNKHBMX-UHFFFAOYSA-N 0.000 description 2
- 235000011089 carbon dioxide Nutrition 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 238000004939 coking Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000001640 fractional crystallisation Methods 0.000 description 2
- 238000004508 fractional distillation Methods 0.000 description 2
- 238000007710 freezing Methods 0.000 description 2
- 230000008014 freezing Effects 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 description 2
- 239000012263 liquid product Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 235000010755 mineral Nutrition 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- LQNUZADURLCDLV-UHFFFAOYSA-N nitrobenzene Chemical compound [O-][N+](=O)C1=CC=CC=C1 LQNUZADURLCDLV-UHFFFAOYSA-N 0.000 description 2
- 239000011541 reaction mixture Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 description 2
- CLTHBVPJKLDVAS-UHFFFAOYSA-N 1,3-ditert-butyl-5-ethylbenzene Chemical compound CCC1=CC(C(C)(C)C)=CC(C(C)(C)C)=C1 CLTHBVPJKLDVAS-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 1
- LGRFSURHDFAFJT-UHFFFAOYSA-N Phthalic anhydride Natural products C1=CC=C2C(=O)OC(=O)C2=C1 LGRFSURHDFAFJT-UHFFFAOYSA-N 0.000 description 1
- 239000010425 asbestos Substances 0.000 description 1
- JHIWVOJDXOSYLW-UHFFFAOYSA-N butyl 2,2-difluorocyclopropane-1-carboxylate Chemical compound CCCCOC(=O)C1CC1(F)F JHIWVOJDXOSYLW-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000005539 carbonized material Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000003009 desulfurizing effect Effects 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000011872 intimate mixture Substances 0.000 description 1
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 1
- 239000001282 iso-butane Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- LYGJENNIWJXYER-UHFFFAOYSA-N nitromethane Chemical compound C[N+]([O-])=O LYGJENNIWJXYER-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- JTXAHXNXKFGXIT-UHFFFAOYSA-N propane;prop-1-ene Chemical compound CCC.CC=C JTXAHXNXKFGXIT-UHFFFAOYSA-N 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 229910052895 riebeckite Inorganic materials 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 235000011121 sodium hydroxide Nutrition 0.000 description 1
- 239000011592 zinc chloride Substances 0.000 description 1
- 235000005074 zinc chloride Nutrition 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/148—Purification; Separation; Use of additives by treatment giving rise to a chemical modification of at least one compound
- C07C7/14875—Purification; Separation; Use of additives by treatment giving rise to a chemical modification of at least one compound with organic compounds
- C07C7/14883—Purification; Separation; Use of additives by treatment giving rise to a chemical modification of at least one compound with organic compounds hydrocarbons
Definitions
- This invention relates to an integrated process for recovering individual xylene isomers from crude xylenes and producing a blended high octane gasoline containing the undesired xylene isomers.
- Crude xylene fractions are produced in commercial quantities by hydroforming naphthenic petroleum distillates and by fractionating the liquid product produced during the coking of coal.
- the crude xylenes produced by either of these methods contain the three xylene isomers in approximately equilibrium concentrations and substantial amounts of ethylbenzene which cannot readily be separated from the xylenes by fractional distillation.
- the crude xylene produced during the coking of coal consists almost entirely of aromatic hydrocarbons, while the crude xylene produced by hydroforming naphthenic petroleum distillates usually contains about 10% of paralfinic hydrocarbons boiling in the boiling range of the xylenes.
- the least valuable of the xylene isomers for the purpose of upgrading gasoline is ortho-xylene.
- This isomer may be separated from the crude xylene by fractional distillation and oxidized to phthalic anhydride.
- a crude xylene stock or a crude xylene stock which has been fractionally distilled to reduce its ortho-xylene content is contacted with separate an overhead fraction consisting predominantly of para-xylene and a bottoms fraction comprising tertiary-butyl-meta-xylene, tertiary-butyl-ethylbenzene, and tertiary-butyl-ortho-xylene.
- the bottoms fraction is then contacted with a catalytic cracking catalyst at a temperaure above about 600 F.
- tertiary-butyl group is quite selectively cracked from the tertiary-butyl xylenes and tertiary-butyl-ethylbenzene to produce predominantly isobutene and the xylenes.
- the isobutene is separated from the reaction product of the cracking step and returned to the alkylation step together with further quantities of the crude xylene feed.
- the contact of the bottoms fraction of the alkylation reaction product with the cracking catalyst is desirably accomplished simply by feeding this bottoms fraction together with a usual cracking charge stock to a catalytic cracking zone.
- this fraction may be fed to a catalytic cracking zone together with a straight run gas oil boiling in the range about 400 to 850 F.
- a cracking catalyst for example, a silica-alumina bead caalytst, at temperatures in the range 800 to 1000 F.
- the gas oil is cracked in the usual manner and the tertiary-butyl groups are cracked from the components of the alkylation bottoms fraction.
- the total reaction product is then fractionally distilled to separate arr-isobutene fraction which is returned to the alkylation step and a gasoline fraction comprising the usual components of a gasoline derived from a catalytically cracked gas oil and, in addition, xylenes and ethylbenzene.
- the alkylation bottoms fraction may also be charged to a catalytic cracking or treating zone in which thermally cracked naphtha, for example, a naphtha boiling in the range about 280 to 600 F., is being treated by contacting it with a silica-alumina cracking catalyst at temperaturcs in the range about 800 to 950 F. to upgrade the thermally cracked naphtha by desulfurizing it, increasing its gum stability, and cracking the higher boiling fractions of the naphtha.
- the alkylation bottoms fraction is cracked to liberate isobuene, xylenes, and ethylbenzene.
- the treated naphtha and alkylation bottoms are fractionally distilled to separate an isobutene fraction which is then returned to the alkylation step together with further quantities of crude xylene and a gasoline fraction comprising the usual gasoline components of the treated naphtha, xylenes and ethylbenzene.
- the alkylation step of the process of the invention is illustrated by the following example.
- EXAMPLE 1 A xylene fraction separated from catalytically reformed naphtha was contacted with isobutene in the presence of substantially anhydrous hydrogen fluoride at a temperature of 0 to 10 C. for a period of 4 hours.
- the xylene mixture introduced into the alkylation zone contained 14% ethylbenzene, 8% ortho-xylene, 48% metaxylene, 18% para-xylene, and 12% of parafiins boiling in the boiling range of the xylenes.
- the amount of isobutene introduced into the alkylation zone was somewhat less than the amount stoichiometrically required to alkylate all of the aromatic hydrocarbons present in the xylene fraction.
- the alkylation reaction product ' may be separated into two fractions, a Cs-fraction rich in paraxylene and a bottoms fraction which is then contacted with a catalytic cracking catalyst under catalytic cracking conditions.
- the bottoms fraction may be recovered in separate cuts, for example, one cut containing l,3-dimethyl-S-tertiary-butylbenzene and small amounts of rneta-tertiary-butylethylbenzene, which boil at 205 and 206 C.
- a second cut containing l,2-dimethyl-tertiary-butylbenzene and para-tertiary-butylethylbenzene boiling at 215 C. and 211 C.; and a cut comprising 3,5- di-tertiary-butylethylbenzene boiling at 260 C. and ditertiary-butylbenzene.
- One or more of these cuts may be processed for the recovery of particular aromatics and the remainder of them contacted with the cracking catalyst under cracking conditions.
- Example 2 The manner in which the bottoms fraction from the alkylation reaction product may be broken up into the original aromatic hydrocarbons and isobutene is illustrated in the following Example 2.
- this example shows the effect of contacting one of the components of the alkylation bottoms fraction, i. e., 1,3-dimethyl-5-tertiary-'butylbenzene, with a silica-alumina catalyst.
- EXAMPLE 2 The feed stock was metered into the upper preheater section of the vertical assembly and the effluent stream passed through a spiral condenser maintained at 60 F. into an ice-cooled receiver. The effluent stream from the receiver passed into a dry ice cooled trap and to a gasometer.
- the apparatus was flushed with nitrogen prior to each run. Carbonized material was determined by raising the temperature to 975 F., while passing air through the apparatus. The carbon dioxide formed was absorbed in Ascarite (potassium hydroxide on asbestos) and weighed.
- the catalyst used was an equilibrium T. C. C. bead catalyst consisting of alumina and 90% silica, the average diameter of the beads was 0.1250.13 inch.
- the product collected in the dry ice cooled traps was vaporized and representative samples analyzed in the mass spectrometer.
- the liquid product collected in the ice trap was distilled in a low temperature Podbielniak column and the C1 to C5 fraction analyzed in the mass spectrometer.
- the bottoms were distilled through a semimicro concentric tube column to separate the xylene fraction. Freezing point analysis of the xylene fractions gave values of 97.7% and 98.1% meta-xylene, respectively.
- the total cracked product is then fractionally distilled to separate an isobutene fraction which is returned to the alkylation step and a gasoline fraction containing the usual products of the cracking or treating of gas oil or naphtha, as the case may be, plus the aromatic hydrocarbons produced by the cracking of the alkylation bottoms fraction.
- the octane number of this gasoline is substantially higher than the octane number of the gasoline produced by cracking or treating of gas oil or naphtha by reason of the presence of these aromatics.
- the alkylation step of the process can be conducted using not only the hydrogen fluoride catalyst shown in Example 1, but any conventional alkylation catalyst and any conventional set of alkylating conditions.
- Catalysts or condensing agents which can be used in the alkylation step include hydrofluoric acid, phosphoric acid, sulfuric acid, Friedel-Crafts catalysts such as zinc chloride, aluminum chloride or ferric chloride, and complexes of Friedel-Crafts catalysts with organic polar liquids such as nitrobenzene, chlorofrom, and nitromethane.
- the alkylation reactions are ordinarily conducted at temperatures in the range about minus 10 to plus 100 C.
- the optimum temperatures for the operable catalysts differ very appreciably, and with some catalysts, such as phosphoric acid on kieselguhr and silica-alumina, may be well above 100 C.
- the catalytic cracking step of the process can be conducted with conventional catalytic cracking catalysts such as the silica-alumina catalysts widely used in the Thermofor catalytic cracking process.
- conventional cracking catalysts such as activated clays and various synthetic catalysts, such as intimate mixtures of two or more metal oxides, such as silica, alumina, magnesia, zirconia, or beryllia, may be employed.
- the cracking step should be conducted at a temperature above about 600 F. in order to remove the tertiarybutyl group from the tertiary-butyl aromatic hydrocarbons contained in the alkylation bottoms fraction.
- temperatures of 600 to 700 F. are adequate.
- the alkylation bottoms fraction is charged to the cracking step together with a straight run gas oil, the usual temperatures for the cracking of the gas oil are employed, i. e., from about 850 to 1000 F.
- somewhat lower temperatures commonly employed in this treatment of the naphtha are used, for example, from about 800 to 925 F.
- An integrated process for separating xylene isomers and producing high octane gasoline which comprises contacting isobutene with a xylene fraction comprising substantial quantities of para-xylene and meta-xylene in the presence of liquid hydrogen fluoride at a temperature in the range l0 to 100 C., the quantity of isobutene employed being sufiicient to alkylate a substantial proportion of the meta-xylene contained in said xylene fraction, fractionally distilling the alkylation reaction product to separate a para-xylene rich fraction and a fraction comprising tertiary-butyl-meta-xylene, contacting the latter fraction and a straight run petroleum distillate with a silicaalumina catalyst in a catalytic cracking zone at a temperature in the range 800 to 1000 F., whereby said latter fraction is cracked forming predominantly metaxylene and isobutene, fractionally distilling the eflluent from the cracking zone to separate a fraction rich in isobut
- An integrated process for separating desired components of a crude xylene and concurrently producing a high octane gasoline which comprises contacting isobutene with a crude xylene fraction in the presence of a mineral acid alkylation catalyst at a temperature in the range to 100 C., the quantity of isobutene employed being sufficient to alkylate a substantial proportion of the aromatic hydrocarbons other than para-xylene contained in said xylene fraction, fractionally distilling the alkylation reaction product to separate an unreacted fraction rich in para-xylene and a reacted fraction comprising tertiarybutyl-alkylbenzenes, and contacting the latter fraction and a petroleum distillate with a solid cracking catalyst in a catalytic cracking zone at a temperature in the range 800 to 1000 F. whereby said latter fraction is cracked forming predominantly isobutene and xylenes other than para-xylene.
- An integrated process for separating desired components of a crude xylene and concurrently producing a high octane gasoline which comprises contacting isobutene with a crude xylene fraction in the presence of a mineral acid alkylation catalyst at a temperature in the range -l0 to C.
- the quantity of isobutene employed being suflicient to alkylate a substantial proportion of the aromatic hydrocarbons other than para-xylene contained in said xylene fraction, fractionally distilling the alkylation reaction product to separate an unreacted fraction rich in para-xylene and a reacted fraction comprising tertiarybutyl-alkylbenzenes, contacting the latter fraction and a petroleum distillate with a solid cracking catalyst in a catalytic cracking zone at a temperature in the range 800 to 1000 F., whereby said latter fraction is cracked forming predominantly isobutene and xylenes other than paraxylene, fractionally distilling the eflluent from the cracking zone to separate a fraction rich in isobutene and a gasoline fraction and returning the isobutene fraction together with further quantities of crude xylene to the alkylation step.
- a process for the separation of p-xylene from a mixture thereof with ethyl benzene, o-xylene and mxylene which comprises subjecting said mixture in the liquid phase to alkylating conditions in the presence of isobutylene and hydrogen fluoride wherein the mole ratio of isobutylene to ethyl benzene, o-xylene, and m-xylene is about 1, whereby said isobutylene alkylates said ethyl benzene, o-xylene, and m-xylene to form the tertiary butyl derivatives thereof, separating p-xylene from the reaction mixture, dealkylating said tertiary butyl derivatives by subjecting said reaction mixture to dealkylating conditions in the presence of a cracking catalyst comprising silica and alumina, to form isobutylene and a mixture of o-xylene, m-Xylene and ethyl
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Description
XYLENE SEPARATION PROCESS Filed March 17, 1951 ISOBU TENE Li J CRUDE XYLENES ALKVLA T/ON PARAXYLENE PARAFF/NS T-BUTVL-O "XVLENE T-BUTYL -M-XVLENE T-BUTVL -ETHYL BENZENE gg fz CA TALVT/C CRACK/N6 o/s T/LL 4 r/o/v q GASOL/NE 0 XYL ENE u ISOBUTENE M-XVLENE. v ETHYL BENZENE I N V E N T O R MA UR/CE J. SCHL A T TER 1 BY g j m.
XYLENE SEPARATION PROCESS Maurice I. Schlatter, El Cerrito, Califl, assignor to California Research Corporation, San Francisco, Cal1f., a corporation of Delaware Application March 17, 1951, Serial No. 216,244
9 Claims. (Cl. 260-474) This invention relates to an integrated process for recovering individual xylene isomers from crude xylenes and producing a blended high octane gasoline containing the undesired xylene isomers.
Crude xylene fractions are produced in commercial quantities by hydroforming naphthenic petroleum distillates and by fractionating the liquid product produced during the coking of coal. The crude xylenes produced by either of these methods contain the three xylene isomers in approximately equilibrium concentrations and substantial amounts of ethylbenzene which cannot readily be separated from the xylenes by fractional distillation. The crude xylene produced during the coking of coal consists almost entirely of aromatic hydrocarbons, while the crude xylene produced by hydroforming naphthenic petroleum distillates usually contains about 10% of paralfinic hydrocarbons boiling in the boiling range of the xylenes. The least valuable of the xylene isomers for the purpose of upgrading gasoline is ortho-xylene.
This isomer may be separated from the crude xylene by fractional distillation and oxidized to phthalic anhydride.
Recently, the separation of para-xylene from the crude xylene fraction has been practiced to supply commercial demands for terephthalic acid produced by oxidation of para-xylene. Para-xylene has been separated from the crude xylene fractions by fractional crystallization. After separation of the ortho-xylene or the para-xylene, or both, from the crude xylene fraction, the remainder of the fraction has been used as a gasoline blending stock in the production of high octane gasolines.
It has now been found that the separation of paraxylene and ortho-xylene from a crude xylene stock, and the blending of the residue of the stock with gasoline to improve its octane rating, may be effected readily and economically by the new process described herein.
Pursuant to the invention, either a crude xylene stock or a crude xylene stock which has been fractionally distilled to reduce its ortho-xylene content is contacted with separate an overhead fraction consisting predominantly of para-xylene and a bottoms fraction comprising tertiary-butyl-meta-xylene, tertiary-butyl-ethylbenzene, and tertiary-butyl-ortho-xylene. The bottoms fraction is then contacted with a catalytic cracking catalyst at a temperaure above about 600 F. and it is found that the tertiary-butyl group is quite selectively cracked from the tertiary-butyl xylenes and tertiary-butyl-ethylbenzene to produce predominantly isobutene and the xylenes. The isobutene is separated from the reaction product of the cracking step and returned to the alkylation step together with further quantities of the crude xylene feed.
The contact of the bottoms fraction of the alkylation reaction product with the cracking catalyst is desirably accomplished simply by feeding this bottoms fraction together with a usual cracking charge stock to a catalytic cracking zone. For example, this fraction may be fed to a catalytic cracking zone together with a straight run gas oil boiling in the range about 400 to 850 F. In the cracking zone both the alkylation bottoms fraction and the gas oil are contacted with a cracking catalyst, for example, a silica-alumina bead caalytst, at temperatures in the range 800 to 1000 F. In the cracking zone the gas oil is cracked in the usual manner and the tertiary-butyl groups are cracked from the components of the alkylation bottoms fraction. The total reaction product is then fractionally distilled to separate arr-isobutene fraction which is returned to the alkylation step and a gasoline fraction comprising the usual components of a gasoline derived from a catalytically cracked gas oil and, in addition, xylenes and ethylbenzene.
The alkylation bottoms fraction may also be charged to a catalytic cracking or treating zone in which thermally cracked naphtha, for example, a naphtha boiling in the range about 280 to 600 F., is being treated by contacting it with a silica-alumina cracking catalyst at temperaturcs in the range about 800 to 950 F. to upgrade the thermally cracked naphtha by desulfurizing it, increasing its gum stability, and cracking the higher boiling fractions of the naphtha. In this catalytic treating step, the alkylation bottoms fraction is cracked to liberate isobuene, xylenes, and ethylbenzene. The treated naphtha and alkylation bottoms are fractionally distilled to separate an isobutene fraction which is then returned to the alkylation step together with further quantities of crude xylene and a gasoline fraction comprising the usual gasoline components of the treated naphtha, xylenes and ethylbenzene.
The alkylation step of the process of the invention is illustrated by the following example.
EXAMPLE 1 A xylene fraction separated from catalytically reformed naphtha was contacted with isobutene in the presence of substantially anhydrous hydrogen fluoride at a temperature of 0 to 10 C. for a period of 4 hours. The xylene mixture introduced into the alkylation zone contained 14% ethylbenzene, 8% ortho-xylene, 48% metaxylene, 18% para-xylene, and 12% of parafiins boiling in the boiling range of the xylenes. The amount of isobutene introduced into the alkylation zone was somewhat less than the amount stoichiometrically required to alkylate all of the aromatic hydrocarbons present in the xylene fraction. After the alkylation reaction was complete, a Cs-fraction was distilled from the reaction product. Analysis of this fraction showed it to contain 6% of the ethylbenzene, 12% of the ortho-xylene, 16% of the meta-xylene, 94% of the para-xylene, and 76% of the paraffins, which had been present in the xylene fraction fed to the alkylation zone. It is evident that relatively little of the ethylbenzene, ortho-xylene and metaxylene remained unalkylated, while very little of the para-xylene was consumed in the reaction. This Csfraction, separated from the alkylation reaction product, consists predominantly of para-xylene and pure paraxylene may be readily recovered from it by fractional crystallization. The alkylation reaction product 'may be separated into two fractions, a Cs-fraction rich in paraxylene and a bottoms fraction which is then contacted with a catalytic cracking catalyst under catalytic cracking conditions. If desired, the bottoms fraction may be recovered in separate cuts, for example, one cut containing l,3-dimethyl-S-tertiary-butylbenzene and small amounts of rneta-tertiary-butylethylbenzene, which boil at 205 and 206 C. and may be recovered in a narrow boiling fraction; a second cut containing l,2-dimethyl-tertiary-butylbenzene and para-tertiary-butylethylbenzene boiling at 215 C. and 211 C.; and a cut comprising 3,5- di-tertiary-butylethylbenzene boiling at 260 C. and ditertiary-butylbenzene. One or more of these cuts may be processed for the recovery of particular aromatics and the remainder of them contacted with the cracking catalyst under cracking conditions.
The manner in which the bottoms fraction from the alkylation reaction product may be broken up into the original aromatic hydrocarbons and isobutene is illustrated in the following Example 2. In order to obtain a material balance and illustrate the relationship between the reaction product and the reactants, this example shows the effect of contacting one of the components of the alkylation bottoms fraction, i. e., 1,3-dimethyl-5-tertiary-'butylbenzene, with a silica-alumina catalyst.
EXAMPLE 2 The feed stock was metered into the upper preheater section of the vertical assembly and the effluent stream passed through a spiral condenser maintained at 60 F. into an ice-cooled receiver. The effluent stream from the receiver passed into a dry ice cooled trap and to a gasometer.
The apparatus was flushed with nitrogen prior to each run. Carbonized material was determined by raising the temperature to 975 F., while passing air through the apparatus. The carbon dioxide formed was absorbed in Ascarite (potassium hydroxide on asbestos) and weighed.
The catalyst used was an equilibrium T. C. C. bead catalyst consisting of alumina and 90% silica, the average diameter of the beads was 0.1250.13 inch.
The product collected in the dry ice cooled traps was vaporized and representative samples analyzed in the mass spectrometer. The liquid product collected in the ice trap was distilled in a low temperature Podbielniak column and the C1 to C5 fraction analyzed in the mass spectrometer. The bottoms were distilled through a semimicro concentric tube column to separate the xylene fraction. Freezing point analysis of the xylene fractions gave values of 97.7% and 98.1% meta-xylene, respectively.
Table l.
Table I Process Data:
Run No 653-431 653-4311 Space Rate, V./V./hr 2.0 4. 0 Catalyst-Oil Ratio, V./V 2.0 2.0 Reactor Wall Temp., "F 750 750 Catalyst Temp., 693 680 Catalyst Activity (Cat 31. 5 31. 5 Weight; of Charge, g... 60 60 Conversion per Pass, Peree 90 Wt. Moles Wt. Moles Percent per of Total Mole Product of Charge Product Data: Fraction Collected at 60 F Fraction Collected at F Carbon Z Product Composition:
Propene Propane. Isobutane l-Bntonps Z-Butenes Isopentane Pentanes...
C -C5 Total Cl- 3 m-xylene L. Unchanged Star g Total Aromatics 1 The total butene value is accurate, but the butene breakdown using only mass-spectrometer data is approximate.
9 Freezing point analyses of the total xylene fraction gave values of 97.7% and 98.1% meta-xylene, respectively.
The foregoing example clearly indicates the manner in which tertiary-butyl-meta-xylene is decomposed to yield principally meta-xylene and isobutene by contacting it with a cracking catalyst under cracking conditions. The tertiary-butyl group is similarly removed from tertiarybutylethylbenzene and tertiary-butyl-ortho-xylene at temperatures of 600? F. and above. This cracking reaction may be carried out by introducing the alkylation bottoms fraction into a catalytic cracking unit charging gas oil, straight run naphtha or thermally cracked naphtha. The cracking of the alkylation bottoms fraction proceeds in the presence of these materials in the same manner as illustrated in Example 2. The total cracked product is then fractionally distilled to separate an isobutene fraction which is returned to the alkylation step and a gasoline fraction containing the usual products of the cracking or treating of gas oil or naphtha, as the case may be, plus the aromatic hydrocarbons produced by the cracking of the alkylation bottoms fraction. The octane number of this gasoline is substantially higher than the octane number of the gasoline produced by cracking or treating of gas oil or naphtha by reason of the presence of these aromatics.
The appended drawing illustrates the process flow employed in one modification of the invention. The conditions under which the specific steps can be performed are described below.
The alkylation step of the process can be conducted using not only the hydrogen fluoride catalyst shown in Example 1, but any conventional alkylation catalyst and any conventional set of alkylating conditions.
Catalysts or condensing agents which can be used in the alkylation step include hydrofluoric acid, phosphoric acid, sulfuric acid, Friedel-Crafts catalysts such as zinc chloride, aluminum chloride or ferric chloride, and complexes of Friedel-Crafts catalysts with organic polar liquids such as nitrobenzene, chlorofrom, and nitromethane. The alkylation reactions are ordinarily conducted at temperatures in the range about minus 10 to plus 100 C. The optimum temperatures for the operable catalysts differ very appreciably, and with some catalysts, such as phosphoric acid on kieselguhr and silica-alumina, may be well above 100 C.
The catalytic cracking step of the process can be conducted with conventional catalytic cracking catalysts such as the silica-alumina catalysts widely used in the Thermofor catalytic cracking process. Other conventional cracking catalysts such as activated clays and various synthetic catalysts, such as intimate mixtures of two or more metal oxides, such as silica, alumina, magnesia, zirconia, or beryllia, may be employed.
The cracking step should be conducted at a temperature above about 600 F. in order to remove the tertiarybutyl group from the tertiary-butyl aromatic hydrocarbons contained in the alkylation bottoms fraction. When the bottoms fraction alone is charged to the cracking step, temperatures of 600 to 700 F. are adequate. When the alkylation bottoms fraction is charged to the cracking step together with a straight run gas oil, the usual temperatures for the cracking of the gas oil are employed, i. e., from about 850 to 1000 F. When the alkylation bottoms fraction is charged to the cracking step together with thermally cracked naphtha, somewhat lower temperatures commonly employed in this treatment of the naphtha are used, for example, from about 800 to 925 F.
Various modifications of the process above described and illustrated will be apparent to those skilled in the art, which modifications lie within the scope of the invention as defined by the appended claims reciting the essential steps of the process.
I claim:
1. An integrated process for separating xylene isomers and producing high octane gasoline which comprises contacting isobutene with a xylene fraction comprising substantial quantities of para-xylene and meta-xylene in the presence of liquid hydrogen fluoride at a temperature in the range l0 to 100 C., the quantity of isobutene employed being sufiicient to alkylate a substantial proportion of the meta-xylene contained in said xylene fraction, fractionally distilling the alkylation reaction product to separate a para-xylene rich fraction and a fraction comprising tertiary-butyl-meta-xylene, contacting the latter fraction and a straight run petroleum distillate with a silicaalumina catalyst in a catalytic cracking zone at a temperature in the range 800 to 1000 F., whereby said latter fraction is cracked forming predominantly metaxylene and isobutene, fractionally distilling the eflluent from the cracking zone to separate a fraction rich in isobutene, and returning the isobutene rich fraction together with additional xylenes to the alkylation step.
2. An integrated process for separating desired components of a crude xylene and concurrently producing a high octane gasoline which comprises contacting isobutene with a crude xylene fraction in the presence of a mineral acid alkylation catalyst at a temperature in the range to 100 C., the quantity of isobutene employed being sufficient to alkylate a substantial proportion of the aromatic hydrocarbons other than para-xylene contained in said xylene fraction, fractionally distilling the alkylation reaction product to separate an unreacted fraction rich in para-xylene and a reacted fraction comprising tertiarybutyl-alkylbenzenes, and contacting the latter fraction and a petroleum distillate with a solid cracking catalyst in a catalytic cracking zone at a temperature in the range 800 to 1000 F. whereby said latter fraction is cracked forming predominantly isobutene and xylenes other than para-xylene.
3. The process as defined in claim 2, wherein the petroleum distillate is a gas oil and the temperature is in the range 850 to 1000" F.
4. The process as defined in claim 2, wherein the petroleum distillate is thermally cracked naphtha and the temperature is in the range 800 to 925 F.
5. An integrated process for separating desired components of a crude xylene and concurrently producing a high octane gasoline which comprises contacting isobutene with a crude xylene fraction in the presence of a mineral acid alkylation catalyst at a temperature in the range -l0 to C. the quantity of isobutene employed being suflicient to alkylate a substantial proportion of the aromatic hydrocarbons other than para-xylene contained in said xylene fraction, fractionally distilling the alkylation reaction product to separate an unreacted fraction rich in para-xylene and a reacted fraction comprising tertiarybutyl-alkylbenzenes, contacting the latter fraction and a petroleum distillate with a solid cracking catalyst in a catalytic cracking zone at a temperature in the range 800 to 1000 F., whereby said latter fraction is cracked forming predominantly isobutene and xylenes other than paraxylene, fractionally distilling the eflluent from the cracking zone to separate a fraction rich in isobutene and a gasoline fraction and returning the isobutene fraction together with further quantities of crude xylene to the alkylation step.
6. The process as defined in claim 5, wherein the petroleurn distillate is a gas oil and the temperature is in the range about 850 to 1000" F.
7. The process as defined in claim 5, wherein the petroleum distillate is a thermally cracked naphtha and the temperature is in the range about 800 to 925 F.
8. The process as defined in claim 5, wherein the alkylation catalyst is hydrogen fluoride and the cracking catalyst is silica-alumina.
9. A process for the separation of p-xylene from a mixture thereof with ethyl benzene, o-xylene and mxylene, which comprises subjecting said mixture in the liquid phase to alkylating conditions in the presence of isobutylene and hydrogen fluoride wherein the mole ratio of isobutylene to ethyl benzene, o-xylene, and m-xylene is about 1, whereby said isobutylene alkylates said ethyl benzene, o-xylene, and m-xylene to form the tertiary butyl derivatives thereof, separating p-xylene from the reaction mixture, dealkylating said tertiary butyl derivatives by subjecting said reaction mixture to dealkylating conditions in the presence of a cracking catalyst comprising silica and alumina, to form isobutylene and a mixture of o-xylene, m-Xylene and ethyl benzene.
References Cited in the file of this patent UNITED STATES PATENTS 2,375,464 Borden May 8, 1945 2,385,524 Mattox Sept. 25, 1945 2,399,781 Arnold May 7, 1946 2,425,858 Beach Aug. 19, 1947 2,435,038 Gilbert et a1. Jan. 27, 1948 2,435,087 Luten et a1. Ian. 27, 1948 2,436,698 Oblad Feb. 24, 1948 2,506,289 Beach et al. May 2, 1950 2,598,715 Nickels June 3, 1952 2,734,930 Schlatter Feb. 14, 1956 OTHER REFERENCES Ipatieff et al.: Jour. Am. Chem. Soc., vol. 59 (1937), pp. 56-60.
Calcott et al.: Jour. Am. Chem. Soc., 61, 1010 (1939).
Nightingale et al.: Jour. Am. Chem. Soc., 63, 258 (1941).
Nightingale et al.: The Alkylation of oand p-xylene, J. A. C. S., vol. 66 (January 1944), pages 154-155.
Thomas et al., I. Am. Chem. Soc., vol. 66, pages 1694-6 (1944).
Claims (1)
1. AN INTEGRATED PROCESS FOR SEPARATING ZYLENE ISOMERS AND PRODUCING HIGH OCTANE GASOLNE WHICH COMPRISESD CONTACTING ISOBUTENE WITH A XYLENE FRACTION COMPRISING SUBSTANTIAL QUANTITIES OF PARA-XYLENE AND META-XYLENE IN THE PRESENCE OF LIQUID HYDROGEN FLUORIDE AT A TEMPERATURE IN THE RANGE -10 TO 100*C., THE QUANTITY OF ISOBUTENE EMPLOYED BEING SUFFICIENT TO ALKYLATE AND SUBSTANTIAL PROPORTION OF THE META-XYLENE CONTAINED IN SAID XYLENE FRACTION, FRACTIONALLY DISTILLING THE ALKYLATION REACTION PRODUCT TO SEPARATE A PARA-XYLENE RICH FRACTION AND A FRACTION COMPRISING TERTIARY-BUTYL-META-XYLENE, CONTACTING THE LATTER FRACTION AND A STRAIGHT RUN PETROLEUM DISTILLATE WITH A SILICA-ALUMINA CATALYST IN A CATALYSTIC CRACKING ZONE AT A TEMPERATURE IN THE RANGE 800 TO 1000*F., WHEREBY SAID LATTER FRACTION IS CRACKED FORMING PREDOMINANTLY METAXYLENE AND ISOBUTENE, FRACTIONALLY DISTILLING THE EFFLUENT FROM THE CRACKING ZONE TO SEPARATE A FRACTION RICH IN ISOBUTENE, AND RETURNING THE ISOBUTENE RICH FRACTION TOGETHER WITH ADDITIONAL XYLENES TO THE ALKYLATION STEP.
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US216244A US2801271A (en) | 1951-03-17 | 1951-03-17 | Xylene separation process |
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US216244A US2801271A (en) | 1951-03-17 | 1951-03-17 | Xylene separation process |
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Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2889382A (en) * | 1957-04-01 | 1959-06-02 | Allied Chem | Process for removing meta-xylene from mixtures of xylene isomers including the para isomer by means of chlorination |
US2931842A (en) * | 1957-02-28 | 1960-04-05 | Atlantic Refining Co | Catalytic dealkylation of alkyl aromatics |
US3178485A (en) * | 1961-12-06 | 1965-04-13 | Phillips Petroleum Co | Thermal hydrodealkylation of alkyl aromatics |
US3284523A (en) * | 1963-07-08 | 1966-11-08 | Sinclair Research Inc | Method for making 5-t-butyl-m-xylene |
WO1993024432A1 (en) * | 1992-05-26 | 1993-12-09 | Exxon Chemical Patents Inc. | Process for improving purity of para-xylene product |
US6489527B1 (en) | 1992-05-26 | 2002-12-03 | John Di-Yi Ou | Process for improving purity of para-xylene product |
Citations (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2375464A (en) * | 1942-06-20 | 1945-05-08 | Citles Service Oil Company | Production of purified aromatic hydrocarbons from petroleum |
US2385524A (en) * | 1944-09-30 | 1945-09-25 | Universal Oil Prod Co | Conversion of hydrocarbons |
US2399781A (en) * | 1942-07-09 | 1946-05-07 | Texas Co | Manufacture of toluene |
US2425858A (en) * | 1947-08-19 | Process fob isomerizing tertiary | ||
US2435087A (en) * | 1943-03-19 | 1948-01-27 | Shell Dev | Process for the separation of mixtures of alkyl phenols through selective alkylation |
US2435038A (en) * | 1944-06-13 | 1948-01-27 | Gulf Research Development Co | Catalytic dealkylation of alkyl aromatic compounds |
US2436698A (en) * | 1945-04-16 | 1948-02-24 | Socony Vacuum Oil Co Inc | Process for separating olefins from hydrocarbon mixtures |
US2506289A (en) * | 1948-10-05 | 1950-05-02 | Standard Oil Dev Co | Process for the sepoaration of isomers |
US2598715A (en) * | 1948-12-31 | 1952-06-03 | Koppers Co Inc | Separation of naphthalene isomers |
US2734930A (en) * | 1956-02-14 | Separation of ethylbenzene from crude |
-
1951
- 1951-03-17 US US216244A patent/US2801271A/en not_active Expired - Lifetime
Patent Citations (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2425858A (en) * | 1947-08-19 | Process fob isomerizing tertiary | ||
US2734930A (en) * | 1956-02-14 | Separation of ethylbenzene from crude | ||
US2375464A (en) * | 1942-06-20 | 1945-05-08 | Citles Service Oil Company | Production of purified aromatic hydrocarbons from petroleum |
US2399781A (en) * | 1942-07-09 | 1946-05-07 | Texas Co | Manufacture of toluene |
US2435087A (en) * | 1943-03-19 | 1948-01-27 | Shell Dev | Process for the separation of mixtures of alkyl phenols through selective alkylation |
US2435038A (en) * | 1944-06-13 | 1948-01-27 | Gulf Research Development Co | Catalytic dealkylation of alkyl aromatic compounds |
US2385524A (en) * | 1944-09-30 | 1945-09-25 | Universal Oil Prod Co | Conversion of hydrocarbons |
US2436698A (en) * | 1945-04-16 | 1948-02-24 | Socony Vacuum Oil Co Inc | Process for separating olefins from hydrocarbon mixtures |
US2506289A (en) * | 1948-10-05 | 1950-05-02 | Standard Oil Dev Co | Process for the sepoaration of isomers |
US2598715A (en) * | 1948-12-31 | 1952-06-03 | Koppers Co Inc | Separation of naphthalene isomers |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2931842A (en) * | 1957-02-28 | 1960-04-05 | Atlantic Refining Co | Catalytic dealkylation of alkyl aromatics |
US2889382A (en) * | 1957-04-01 | 1959-06-02 | Allied Chem | Process for removing meta-xylene from mixtures of xylene isomers including the para isomer by means of chlorination |
US3178485A (en) * | 1961-12-06 | 1965-04-13 | Phillips Petroleum Co | Thermal hydrodealkylation of alkyl aromatics |
US3284523A (en) * | 1963-07-08 | 1966-11-08 | Sinclair Research Inc | Method for making 5-t-butyl-m-xylene |
WO1993024432A1 (en) * | 1992-05-26 | 1993-12-09 | Exxon Chemical Patents Inc. | Process for improving purity of para-xylene product |
US6489527B1 (en) | 1992-05-26 | 2002-12-03 | John Di-Yi Ou | Process for improving purity of para-xylene product |
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