CA1098547A - Etherification processing of light hydrocarbons - Google Patents
Etherification processing of light hydrocarbonsInfo
- Publication number
- CA1098547A CA1098547A CA312,338A CA312338A CA1098547A CA 1098547 A CA1098547 A CA 1098547A CA 312338 A CA312338 A CA 312338A CA 1098547 A CA1098547 A CA 1098547A
- Authority
- CA
- Canada
- Prior art keywords
- methanol
- glycol
- hydrocarbons
- stream
- effluent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 229930195733 hydrocarbon Natural products 0.000 title claims abstract description 81
- 150000002430 hydrocarbons Chemical class 0.000 title claims abstract description 74
- 238000006266 etherification reaction Methods 0.000 title claims abstract description 31
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 216
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims abstract description 101
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 claims abstract description 34
- 239000000203 mixture Substances 0.000 claims abstract description 29
- TVMXDCGIABBOFY-UHFFFAOYSA-N octane Chemical compound CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 claims abstract description 24
- 239000004215 Carbon black (E152) Substances 0.000 claims abstract description 18
- 239000007788 liquid Substances 0.000 claims abstract description 16
- 239000003054 catalyst Substances 0.000 claims abstract description 5
- 230000003197 catalytic effect Effects 0.000 claims abstract 2
- 238000000034 method Methods 0.000 claims description 29
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 23
- 125000004432 carbon atom Chemical group C* 0.000 claims description 22
- 150000002170 ethers Chemical class 0.000 claims description 16
- 238000009835 boiling Methods 0.000 claims description 13
- 238000002156 mixing Methods 0.000 claims description 13
- 229910052799 carbon Inorganic materials 0.000 claims description 12
- 150000001336 alkenes Chemical class 0.000 claims description 11
- 238000004064 recycling Methods 0.000 claims description 6
- 230000006872 improvement Effects 0.000 claims description 4
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- VQTUBCCKSQIDNK-UHFFFAOYSA-N Isobutene Chemical group CC(C)=C VQTUBCCKSQIDNK-UHFFFAOYSA-N 0.000 abstract description 8
- BKOOMYPCSUNDGP-UHFFFAOYSA-N 2-methylbut-2-ene Chemical group CC=C(C)C BKOOMYPCSUNDGP-UHFFFAOYSA-N 0.000 abstract description 5
- 230000002939 deleterious effect Effects 0.000 abstract description 3
- 230000008569 process Effects 0.000 description 16
- 238000004821 distillation Methods 0.000 description 15
- 238000005804 alkylation reaction Methods 0.000 description 13
- BZLVMXJERCGZMT-UHFFFAOYSA-N Methyl tert-butyl ether Chemical compound COC(C)(C)C BZLVMXJERCGZMT-UHFFFAOYSA-N 0.000 description 10
- 230000029936 alkylation Effects 0.000 description 10
- -1 carbon atom compounds Chemical class 0.000 description 9
- 238000000605 extraction Methods 0.000 description 8
- 238000004508 fractional distillation Methods 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 6
- 239000006096 absorbing agent Substances 0.000 description 4
- 238000000622 liquid--liquid extraction Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000000638 solvent extraction Methods 0.000 description 4
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 3
- 125000004429 atom Chemical group 0.000 description 3
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 description 3
- 239000004615 ingredient Substances 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000011109 contamination Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000005194 fractionation Methods 0.000 description 2
- 150000002334 glycols Chemical class 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000002808 molecular sieve Substances 0.000 description 2
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- GTPDHYQKBSCXAP-ZETCQYMHSA-N (2s)-4-methylsulfanyl-2-(thiophene-2-carbonylamino)butanoic acid Chemical compound CSCC[C@@H](C(O)=O)NC(=O)C1=CC=CS1 GTPDHYQKBSCXAP-ZETCQYMHSA-N 0.000 description 1
- DBUJFULDVAZULB-UHFFFAOYSA-N 1-methoxypentane Chemical compound CCCCCOC DBUJFULDVAZULB-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 150000001721 carbon Chemical group 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000004587 chromatography analysis Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 150000001983 dialkylethers Chemical class 0.000 description 1
- MDKXBBPLEGPIRI-UHFFFAOYSA-N ethoxyethane;methanol Chemical compound OC.CCOCC MDKXBBPLEGPIRI-UHFFFAOYSA-N 0.000 description 1
- ZZUFCTLCJUWOSV-UHFFFAOYSA-N furosemide Chemical compound C1=C(Cl)C(S(=O)(=O)N)=CC(C(O)=O)=C1NCC1=CC=CO1 ZZUFCTLCJUWOSV-UHFFFAOYSA-N 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- UOAURXFOXHOVOU-UHFFFAOYSA-N methanol;pentane Chemical compound OC.CCCCC UOAURXFOXHOVOU-UHFFFAOYSA-N 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- ZIBGPFATKBEMQZ-UHFFFAOYSA-N triethylene glycol Chemical class OCCOCCOCCO ZIBGPFATKBEMQZ-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C41/00—Preparation of ethers; Preparation of compounds having groups, groups or groups
- C07C41/01—Preparation of ethers
- C07C41/34—Separation; Purification; Stabilisation; Use of additives
- C07C41/40—Separation; Purification; Stabilisation; Use of additives by change of physical state, e.g. by crystallisation
- C07C41/42—Separation; Purification; Stabilisation; Use of additives by change of physical state, e.g. by crystallisation by distillation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C41/00—Preparation of ethers; Preparation of compounds having groups, groups or groups
- C07C41/01—Preparation of ethers
- C07C41/05—Preparation of ethers by addition of compounds to unsaturated compounds
- C07C41/06—Preparation of ethers by addition of compounds to unsaturated compounds by addition of organic compounds only
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C41/00—Preparation of ethers; Preparation of compounds having groups, groups or groups
- C07C41/01—Preparation of ethers
- C07C41/34—Separation; Purification; Stabilisation; Use of additives
- C07C41/38—Separation; Purification; Stabilisation; Use of additives by liquid-liquid treatment
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
Abstract
IMPROVEMENTS IN ETHERIFICATION
PROCESSING OF LIGHT HYDROCARBONS
Abstract In the processing of olefinic hydrocarbon mixtures containing isobutylene and isoamylene which are etherified with methanol to obtain higher octane components, unreacted methanol is removed from the etherified mixture by contact with a separate liquid glycol phase before unreacted hydrocarbons, substantially free of methanol, are distilled from the etherified mixture for further catalytic processing in which methanol is deleterious to the catalyst.
PROCESSING OF LIGHT HYDROCARBONS
Abstract In the processing of olefinic hydrocarbon mixtures containing isobutylene and isoamylene which are etherified with methanol to obtain higher octane components, unreacted methanol is removed from the etherified mixture by contact with a separate liquid glycol phase before unreacted hydrocarbons, substantially free of methanol, are distilled from the etherified mixture for further catalytic processing in which methanol is deleterious to the catalyst.
Description
5~
This inver,t.lon xelates to improvements in the processing of light olefinic hy~rocarbon streams containing tertiary olefins and more particularly to processincJ in which the tertiary olefins in such streams are subjected to etherification and the remaini.ng hydrocarbons in the streams are subsequently to be subjected to additional processing to produce high octane components suitable for blending into gasoline.
It is known in the art that olefinic mixtures of light hydrocarbons of predomi.nantly four carbon atoms each can be processed to provide high octane gasoline ingredients by etherifying the isobutylene cornponent thereof with methanol to convert the isobutylene to methyl tertiarybutyl ether (MTBE), a high octane ingredient for gasoline blending, and optionally further processing the remaining hydrocarbons of the mixtures to convert other components thereof to compounds of higher octane value, for example by pol~nerization or alkylation processes for making polygas and alkylate respectively. It is also known in the art that olefinic mixtures of hydroca.rbons containing predominantly five carhon atoms each can be processed to convert most of the isoamylene content thereof to tertiary~
amyl methyl ether (TP~IE) which is another high octane ingredi.ent suitable for blendin~ into gasoline. It has further been suggested in the art that olefinic mixtures containing hydro~
carbons of both four and f.ive carbon atoms each can be processed in an etherification reactor to convert simultaneously both four and ~ive carbon atom tertiary olefins therein to the tertiary ethers MTBE and TP~IE. USP 3,482,g52 suggests R,~
etherlfication of an even more ~omplex olefinic mixture of hydrocarbons with ~rom four to six carbon atoms inclusive, to form tertiary ethers of higher octane rating than the original hydrocarbon fraction, distillatlon to separate a hi.gher boiling ether containing portion from the remaining hydrocarbons, and alkylation of the portion of remaining hydrocarbons to form a higher octane alkylated ingredient . suitable for gasoline.
Because the etherification reaction between tertiary olefins and methanol .is an equilibrium reaction, it is not possible to reduce the concentration of methanol in the effluent from the etherification process below the equilibrium concentration of methanol and ether products~
Thus such effluent always contains some methanol. It is now known that such methanol, on distillation of the effluent, forms minimum boillng binary aæeotropes, not only Wit}l the ethers MTBE and TAM~ and a number of the higher boiling hydrocarbons in the C5~C6 range, but also even with n-butane. Thus any attempt to fractionate, simply by distillation, tlle effluent of a process etherifying a mixture of C4-C6 hydrocarbons with methanol, is bound to produce a distillate containing some methanol; even a distillate free of binary ether-methanol azeotropes from such ef1uent contains some methanol~n-butane azeotrope (and some methanol pentane azeotrope if C5 hydrocarbons are taken into the distillate). Becallse methanol is so deleterious to the catalysts usually used in alkylatioll processes or in the pol~merization process for p;oduction of polygas, lt is not ~ 2 5~7 practi.cable to u6e, in such processes, the effluellt from the etherification proces-i in which an olefinic C~-C6 hydrocarbon raction is etherified with methanol, even if the effluent. is distilled to separate higher boiling material, notably the ethers, from the hydrocarbon material to be fuxther processed by alkylation or polymerizationO
The art of preparing the e-thers MTBE and TA~IE
from olefinic mixtures of hydrocarbons also has indicated a preference for separately etherifying olefinic mixtures of hydrocarbons of predom:irlantly four carbon atoms each and olefinic mixtures of hydrocarbons of predominantly five carbon atoms.each rather than etherifyin~ them in admixture, in significant part because of the difficulty of separating, from the effluent of a process for their combined etherification, hydrocarbon streams of suffic.iently low methanol content to be . suitable for subsequent processing by al~ylation or polymerization.
It has llOW ~een found that, by means o a combination of either an absorption or an extraction step and one or more simple frdctional distillation steps, it is possible to separate the
This inver,t.lon xelates to improvements in the processing of light olefinic hy~rocarbon streams containing tertiary olefins and more particularly to processincJ in which the tertiary olefins in such streams are subjected to etherification and the remaini.ng hydrocarbons in the streams are subsequently to be subjected to additional processing to produce high octane components suitable for blending into gasoline.
It is known in the art that olefinic mixtures of light hydrocarbons of predomi.nantly four carbon atoms each can be processed to provide high octane gasoline ingredients by etherifying the isobutylene cornponent thereof with methanol to convert the isobutylene to methyl tertiarybutyl ether (MTBE), a high octane ingredient for gasoline blending, and optionally further processing the remaining hydrocarbons of the mixtures to convert other components thereof to compounds of higher octane value, for example by pol~nerization or alkylation processes for making polygas and alkylate respectively. It is also known in the art that olefinic mixtures of hydroca.rbons containing predominantly five carhon atoms each can be processed to convert most of the isoamylene content thereof to tertiary~
amyl methyl ether (TP~IE) which is another high octane ingredi.ent suitable for blendin~ into gasoline. It has further been suggested in the art that olefinic mixtures containing hydro~
carbons of both four and f.ive carbon atoms each can be processed in an etherification reactor to convert simultaneously both four and ~ive carbon atom tertiary olefins therein to the tertiary ethers MTBE and TP~IE. USP 3,482,g52 suggests R,~
etherlfication of an even more ~omplex olefinic mixture of hydrocarbons with ~rom four to six carbon atoms inclusive, to form tertiary ethers of higher octane rating than the original hydrocarbon fraction, distillatlon to separate a hi.gher boiling ether containing portion from the remaining hydrocarbons, and alkylation of the portion of remaining hydrocarbons to form a higher octane alkylated ingredient . suitable for gasoline.
Because the etherification reaction between tertiary olefins and methanol .is an equilibrium reaction, it is not possible to reduce the concentration of methanol in the effluent from the etherification process below the equilibrium concentration of methanol and ether products~
Thus such effluent always contains some methanol. It is now known that such methanol, on distillation of the effluent, forms minimum boillng binary aæeotropes, not only Wit}l the ethers MTBE and TAM~ and a number of the higher boiling hydrocarbons in the C5~C6 range, but also even with n-butane. Thus any attempt to fractionate, simply by distillation, tlle effluent of a process etherifying a mixture of C4-C6 hydrocarbons with methanol, is bound to produce a distillate containing some methanol; even a distillate free of binary ether-methanol azeotropes from such ef1uent contains some methanol~n-butane azeotrope (and some methanol pentane azeotrope if C5 hydrocarbons are taken into the distillate). Becallse methanol is so deleterious to the catalysts usually used in alkylatioll processes or in the pol~merization process for p;oduction of polygas, lt is not ~ 2 5~7 practi.cable to u6e, in such processes, the effluellt from the etherification proces-i in which an olefinic C~-C6 hydrocarbon raction is etherified with methanol, even if the effluent. is distilled to separate higher boiling material, notably the ethers, from the hydrocarbon material to be fuxther processed by alkylation or polymerizationO
The art of preparing the e-thers MTBE and TA~IE
from olefinic mixtures of hydrocarbons also has indicated a preference for separately etherifying olefinic mixtures of hydrocarbons of predom:irlantly four carbon atoms each and olefinic mixtures of hydrocarbons of predominantly five carbon atoms.each rather than etherifyin~ them in admixture, in significant part because of the difficulty of separating, from the effluent of a process for their combined etherification, hydrocarbon streams of suffic.iently low methanol content to be . suitable for subsequent processing by al~ylation or polymerization.
It has llOW ~een found that, by means o a combination of either an absorption or an extraction step and one or more simple frdctional distillation steps, it is possible to separate the
2~ effluent from an etherification process, in which an ole~inic : mixture of hydrocarbons contalning predominantly both four and f ive carbon atom compounds is etherified with me-thanol, to provide a fraction containing substantially all of the ethers and at least one other fraction containing hydrocarbons substantially ~ree o~ methanol and suitable for urther processing, for example, by alkylation, polymerization to polygas, or other process in which methanol i.s deleterious to operation. Such alkylation, polymerixation and other processes 7~
recJularly r-quire feeds containing less than 200 mole ppm of methanol, pxeferrabl.y less than 50 mole ppm and most pr~ferrably less than 10 mole ppm of methanol.
The present invent.ion thus consists in a methocl for processing an olefinie hydroearbon stream, consisting essential].y of a mixture including both four and five earbon atom etherifiable olefins, for the formation of high octane components for ~lending into gasoline, said method eomprising 1. passing said stream into an etherification reactor with a proporti.on of methanol under etherifying conditions, to contact an etherifieation eatalyst therein and etherify tertiary olefins in said stream, 2. passing the entire effluent stream from said etherifieation reaetor into a glycol eontaeting unit and eontaeting it therein with a stream of liquid glyeol to remove methanol from said effluent and reduee the methanol eoneentxation in the effluen.t stream to no greater than 200 mole ppm in said effluent,
recJularly r-quire feeds containing less than 200 mole ppm of methanol, pxeferrabl.y less than 50 mole ppm and most pr~ferrably less than 10 mole ppm of methanol.
The present invent.ion thus consists in a methocl for processing an olefinie hydroearbon stream, consisting essential].y of a mixture including both four and five earbon atom etherifiable olefins, for the formation of high octane components for ~lending into gasoline, said method eomprising 1. passing said stream into an etherification reactor with a proporti.on of methanol under etherifying conditions, to contact an etherifieation eatalyst therein and etherify tertiary olefins in said stream, 2. passing the entire effluent stream from said etherifieation reaetor into a glycol eontaeting unit and eontaeting it therein with a stream of liquid glyeol to remove methanol from said effluent and reduee the methanol eoneentxation in the effluen.t stream to no greater than 200 mole ppm in said effluent,
3. separating said effluent stream irom said glycol and fraetionally dis~illing the reduced ef1uent to separate a distillate eontaining hydrocarbons of predominantly four~earbon atorns each and no greater than 200 mole ppm methanol from a higher boiling high octane fraction containing ethers and hydrocarbons of predominantly more than four carhon 25 atoms each. The invention further consists in a proeess as aforesaid and ineluding the additional step of ractionally distilllng a proportion of said higher boiling fraction to separate a distil.late of hydrocarbons of predominantly fi~e carbon atoms each from a hi.gher boiling ether containing
- 4 -portlon, arld recycling said d.isti.llate of hydrocarbons of predominantly fi.ve carbon atoms each as additional feed to said etherification react.or. The inventioll still further consists in a process as aforesald and including the additional steps of fractionally distilling the glycol separated from the effluent stream to obtain a distillate of methanol and a residue of glycol, recycling said distillate of methanol as part of the methanol ~eed to said etherification reactor and recycling said residue of glycol to said g].ycol contacting unit as the stream of lic~uid gl~col~
The invention may be more readi:Ly understood from the follow.ing description of the accompanying drawing which shows in diagrammatical. form a f].ow sheet illustrating optional em~odiments of the process of the invention~ In lS accordance with the invention an olefinic stream of mixed hydrocarbons contai.ni.ng substanti,~lly only hydrocarbons of four and five carbon atoms each :is suppl.ied by a :Eeed line 1 into an etherification reactor 3; a second feed line 2 feeds a stream of methanol to the reactor. In the reactor the methanoL and hydrocarbons contact an etherification catalyst undex etherifying conditions, thereby converting a lar~e proportion o the tertiary olefins of the mixed hydrocarbon stream to tertiary ethers. ~he mixed stream of ethers and unreacted methanol and hydrocarbons flows from the reactor through line 4 into a counter-current ext.ractor 5 where it contacts a stream of ethylene glycol fxom rec,vcle line 36 or added to the extractor via line 6. In the extractor, unreacted methanol i5 extracted from the ether hydrocarbon ~trealll into the et:hylelle glycol s~rear.l. The ethylene glycol stream containi.ng methanol is withdrawn from the extractor by l.ine 7 and passes to a fractional distillation column 8, conveniently equipped with a condenser 9 and reboiler 10.
S The distillation column separates the methanol, which is withdrawn at the top of the column and is returned by line 11 as part of the methanol feed to reactor 3, from ethylene glycol which is withdrawn at the bottom of the column by line 36 for recycle to the extractor 5. Thè mixed ether-hydrocarbon stream, substantially completely freed of methanol, is with-drawn from the extractor 5 by line 12 and passed to a fractional distillation column 13 equipped with a condensex 14 and reboiler 15. In the distillation column 13 the lower boiling hydrocarbons containing predominantly four carbon atoms each are separated and withdrawn as a distillate stream from the top of the column via line l6. This stream of mixed hydrocarbons containing predominantly four carbon atoms each, being substantially completely free of methanol, is suitable for feeding directly to an alkylation ~nit or to a polygas unit for production of alkylate or poly~as fractions to blend into gasoline. From the bottom of column 13 a residue stream 17, containing ethers produced in reactor 3 and hydrocarbons of predominantly more than four carbon atoms eachr can be withdrawn via line.l7B and passed directly to gasoline blending, for which it is.a high octane component and eminently suitedO
This residue stream 17 from the bo~tom of column 13 contains substantially all the ethers formed from the tertialy h~dro~
carbons ~both.isobutylene and isoamylene) in the olefinic 35~
mixtu.re of hydr~)Garbons origina1.ly fed to the etheriication reactor; it additi~nally contains hydrocarbons of predominantly five carbon atoms each, includin~ some isoamylene which passed unreacted through the etherlfication reactor, and usually some
The invention may be more readi:Ly understood from the follow.ing description of the accompanying drawing which shows in diagrammatical. form a f].ow sheet illustrating optional em~odiments of the process of the invention~ In lS accordance with the invention an olefinic stream of mixed hydrocarbons contai.ni.ng substanti,~lly only hydrocarbons of four and five carbon atoms each :is suppl.ied by a :Eeed line 1 into an etherification reactor 3; a second feed line 2 feeds a stream of methanol to the reactor. In the reactor the methanoL and hydrocarbons contact an etherification catalyst undex etherifying conditions, thereby converting a lar~e proportion o the tertiary olefins of the mixed hydrocarbon stream to tertiary ethers. ~he mixed stream of ethers and unreacted methanol and hydrocarbons flows from the reactor through line 4 into a counter-current ext.ractor 5 where it contacts a stream of ethylene glycol fxom rec,vcle line 36 or added to the extractor via line 6. In the extractor, unreacted methanol i5 extracted from the ether hydrocarbon ~trealll into the et:hylelle glycol s~rear.l. The ethylene glycol stream containi.ng methanol is withdrawn from the extractor by l.ine 7 and passes to a fractional distillation column 8, conveniently equipped with a condenser 9 and reboiler 10.
S The distillation column separates the methanol, which is withdrawn at the top of the column and is returned by line 11 as part of the methanol feed to reactor 3, from ethylene glycol which is withdrawn at the bottom of the column by line 36 for recycle to the extractor 5. Thè mixed ether-hydrocarbon stream, substantially completely freed of methanol, is with-drawn from the extractor 5 by line 12 and passed to a fractional distillation column 13 equipped with a condensex 14 and reboiler 15. In the distillation column 13 the lower boiling hydrocarbons containing predominantly four carbon atoms each are separated and withdrawn as a distillate stream from the top of the column via line l6. This stream of mixed hydrocarbons containing predominantly four carbon atoms each, being substantially completely free of methanol, is suitable for feeding directly to an alkylation ~nit or to a polygas unit for production of alkylate or poly~as fractions to blend into gasoline. From the bottom of column 13 a residue stream 17, containing ethers produced in reactor 3 and hydrocarbons of predominantly more than four carbon atoms eachr can be withdrawn via line.l7B and passed directly to gasoline blending, for which it is.a high octane component and eminently suitedO
This residue stream 17 from the bo~tom of column 13 contains substantially all the ethers formed from the tertialy h~dro~
carbons ~both.isobutylene and isoamylene) in the olefinic 35~
mixtu.re of hydr~)Garbons origina1.ly fed to the etheriication reactor; it additi~nally contains hydrocarbons of predominantly five carbon atoms each, includin~ some isoamylene which passed unreacted through the etherlfication reactor, and usually some
5 SiX carbon hydrocarbons. As an optional feature of this invention, part of this initially unreacted isoamylene is recycled to the etherification reactor by separating a proportion of the residue stream 17 and passing it via line 17A for additional processing illustrated in the part of the drawing enclosed by the dotted rectanyleO The proportion of residue stream to be additionally processed is fed by line 17A
to a fractional distillation column 18 equipped with a condenser 19 and a reboiler 20. This column is operated to separate the ethers and the higher boiling part of the hydro-carbons through the bottom of the column via line 21 and themore volatile predominantly five carbon atom hydrocarbons, includiny the isoamylenes, which dist:ill thxough the top of the column, via line 22. Line 22 condllcts this more volati.le fraction back to reactor 3 where t.he isoamylenes in the fraction are again subject to etherification alon~ with the hydrocarbon feed stream from line 1, The proportion of the residue stream 17 from column 13 which is passed through line 17A for recycle processing can vary between zero and 100 percent of the stream. When none of the stream is taken, the process of the invention acllieves only single pass conversion to TAME of the isoamylenes in the feed which~ with the excellent single pass conversion of isobutylene to MT~E that can be achieved r may be suficient to provide the desired ~8SgL7 octane improvement of the feed stream, particularly in combination with the aclditional octane improvement that can be obtained by the alkylation or other treatment of the stream of hydrocarbons of preclominantly four carbon a~oms recovered from line 16. When 100~ of the residue stream 17 from column 13 is directed through line 17A, the ether containing residue from the bottom of column 13 is all subjected to a fractional distillation which requires significant quantities of heat, the cost of which may not be warranted for the incremental increase in octane which is achieved by such a high degree of recycling. It is more expedient therefore to recycle considerably less than the total amount of the residue stream 17 from column 13, and a preferred proportion for recycle through line 17A is between 10% and 85~ of the residue stream 17 and more preferrably between 15% and 40~ of said stream.
When a recycle portion is withdrawn through line 17~ and fractionall~v distilled in column 18, the higher boiling, ether containing bottom fraction wi~hdrawn through line 21 is a superior octane component for gasoline blending.
2~ ~he glycol contacting unit for removal of methanol from the effluent stream of the etherification reactor, as referred to above, may be either a liquid-liquid type or a vapor absorber type, but preferrably is of the liquid-liquid type, most preferrably the counter-current liquid-liquid type. The vapor absorber type of contacting unit requires that the etherification reactor effluent all he vaporized before passing to the contacting unit, which incrèases the ~emoval costs, therefore liquid--liquid extraction UIlitS are 5~
pre.erre~d, a~ th~ are genera.lly at least as efficient as the vapor absorber type of corltacting unit. The liquid glycol stream which i.s used to contact the reactor effluent stream for extraction of methanol therefrom can be a single li~uid glycol or a mixture of liquid glycols, for example ethylene glycol, diethylene glycol, trieth~lene glycoll propylene glycol, and mixtures of any of these. The essential property of the liquid glycol i.n the extracti.on unit is its ability, as a separate phase, to absorb or extract substantially all of the methanol from the effluent and leave substantiall.y all the dialkyl ethers in admixture with the hydrocarbons of the effluent for blending into gasoline~ The simple (mono)ethylene glycol is the best and most preferred, as it combines optimum properties of extractant for methanol and low miscibil.ity with MTBE and TAME. Di- and triethylene glycols are operable but less preferred because of lower solubility for methanol and increased miscibility with MTBE and TAME.
The temperature at which the methanol removal ; unit is operated generally is lower when using liquid-liquid extraction ~han when using a gas absorber type of unit. In either case it generall.y is in the range from lO~F (-12C) to 450F (232C) and with the pre~erred liquid-liquid extraction units it~is preferrably in the r.ange from 50F to 150F (10C
to 650Cj. The mole flow rate of glycol~ in proportion to the mole flow rate o eff].uent in the contactlng unit, may be in the range from 0.10 to 4.0; preferrabl~ it is in the range from 0.20 to 0.70.
r~ 9 ~-35~7 C'onventional con~ercial eclui.pment for conventional gas absorpti.on or li.quid~liquid extraction operations is suitable for the mei:hanol removal unit required in the present invention. In particular, both packed and pla-te type vapor-li~uid contacting columns are suitable for gas absorption if desired, and likewise either type of column can be used for liquid-liquid extraction. Additionally, other types of mechanical liquid-liquid contactors e.g. rotating disk contactors, can be used. Both counter-current and co-current liquid-liquid extractors are suitable, wi-th the more efficient counter-current type being preferred.
The invention may be more readily unders-tood from the followi.ng specific examples thereof which are given for illustration only and not to limit the following claims~ The proportions given therein and throughout the specification and claims are proportions by weight unless otherwise specifically indi.cated.
EX~MPLE 1 An olefi.nic mixed hydrocarbon stream of hydro-carbons of predominantly four and five carbon atoms was separated from the products of a catalyti.c cracklng operation, principally by fractional distillation; chromatographic analysis of the stream established that its composition was made up of 53.5~ of four carbon atom hydrocarbons including 7.5% C4 reactable with methanol to form ether (i.e. isobutylene) and 46.0~ unreactable C4'sr 39.5% of five carbon atom hydro carbons i~cluding 16.7% C5's reactable with methanol to form -- 10 ~
ether (i.e. isoamylenes) and 22.8~ unreacta~le C5ls, and 7 of six carbon atom hydrocarbons (considered unreactable), This stream was fed continuously, together with a stream of methanol, into a tubular reactor packed with "Ionac C-252"
(Trademark) commercial ion e~change resin in the acid form, used as an etherification catalyst; the molar ratio of methanol to total reactable C4 and C5 hydrocarbons in the reactor feed was maintained at 1.30. The total flow of feed to the reactor provided a liquid hourly space velocity in the reactor of 2.5. Pressure in the reactor was maintained around 13.6 atmospheres and temperature of the feed to the reactor at 160F (71~C). Average temperature across the reactor during the exothermic reaction therein was 184F
(84C). The etherification reactor effluent contained 6.5%
methanol, which could not be adequately separated from the other components of the effluent by fractional distillation.
The effluent was fed continuously, at a rate of 5.3 lb. moles per hour, to the bottom o a continuous counter-current packed ~ed extraction column, 2 inches (5 cm) in diameter and 14 feet (4 3 m~ high, maintained at a pressure of 3.8 atmospheres. A counter~current stream of ethylene glycol at a temperature of 72F (22C) was fed to the top of the extraction column at a mole ratio of 0~45 in proportion to the feed to the bottom of the column. Extracted effluent (raffinate~, withdrawn from the top of the column, was found to contain 10 mole ppm of methan~l and was passed to the middle of a two-inch (5 cm~ diameter distillation sieve tray colu~l having 30 ~ray~. A distillate fraction of hydrocarbons o~ predomiIlcln-Lly our carbon atoms ;~as obtained rom the top of this column and was su~stant~ally free (less than lO mole ppm or 5 weight ppm) of methanol and eminently suitable as feed for either an alkylation process or a polymeriæation proces~ for production of high octane components for yasoline blending. The residue fraction withdrawn continuously from the bottom of the distillation column was a high octane component for gasoline blending and upon analyses by gas chromatography was found to have the following composition:
C~mp~nent Weight Unreactable C4's 2,05 Reactable C4's n . 04 Unreactable C5's51.14 Reactable C5's 14,86 lS C6 ~Iydrocarbons 6.70 Methanol 0,0005 M.T.B.E. 12~90 T.A.M.E. 12.30 The proportions of reactable C4 and C5 hydrocarbons in the original feed stream that were converted to ethers and recovered in this blendiny component were 70~ and 32%
respectively in this sinyle pass reaction. The ethylene glycol extract withdrawn from the bottom of the extraction column was found to contain 7.8% methanol and was fed to a packed stripping column in which the methanol was stripped from the ylycol and recycled to the etherification reactor;
stripped ethylene glycol containiny 150 ppm methanol was recycled from the bottom o the strippiny column to the top of the extraction column for urther extraction of methanol.
3S~7 ~Y~PLE 2 ~ n olefinic rnixed hydrocarbon stream of origin similar ~o that of ~he hydrocar~on mixture used as feed in the previous example was used as raw material in this example and had the following proximate composition: 45.8% C4 hydro-carbons, including 7.9~ isobutylene and 37.9% C4 h~drocarbons unreactable for MTB~ production, 48.8% C5 hydrocarbons including 16.5~ isoamylenes and 32,2% C5 hydrocarbons unreactable to form TAME, and 5~5~ C~ hydrocarbons ~considered unreactable). Utilizing the apparatus used in Example 1 and additionally a 25-plat:e sieve tray fractional distillation column two inches in diameter, with its associated condenser and reboiler, the apparatus was arran~ed as shown diagrammatically in the accompanying drawing with the additional column used for fractionation of a recycle stream. The olefin.ic hydro-carbon stream was fed continuously to the reactor together with a recycle portion obtai.ned as a dist.illate from the top of the foregoing additional sieve tray column; the recycle stream is fuxther identified later herein~ Simultaneously a stream of methanol was fed to the xeactor in a molar ratio of 0.91 relative to the reactable C4 and C5 hydrocarbons in the total reactor feèd. The total reactor feed rate produced an LHSV of 2.0 in the reactor r and the average temperature across the reactor was 180F (82C). Pressure in the reactor was maintained around 13.6 atmospheres. Effluent from the etherification reactor was extracted by a counter~current stream of ethylene glycol in the same manner as in Example 1, and the raffinate dist.illed as in Example 1, to provide a di~s-tillate of mixed ~ 13 ~
a~
prcdominantly C'4 hydrocarbons suhst~ntially free of methanol (less than 10 mole ppm) and suitahle as feed for high octane alkylate or polygas production. A proportion of 30% of the residue from this first distillation was passed to the additional distillation column referred to above, whe.rein it was fractionated to provide a hydrocarbon distillate of pre-dominantly five carbon atom hydrocarbons and a high octane residue containing MTBE and TA~lE formed in the reactor, along with the less volatile of the C5 hydrocarbons and any hi.gher boiliny hydrocarbons in the feed. The remaining 70% of the residue from the irst distillation was a hish octane blending - component suitable for blending directly into a gasoline pool.
Fractionation in this additional distillation column was controlled to remove, in the distillate, most of the etherifiable C5 hydrocarbons (isoamylenes) fed into the column from the preceding distillat:Lon. This distillate, which contained 1.76~ C~ hydrocarbons, 97,23% C5 hydrocarbons including 21.70% isoamylenes, 1.53% C~j hydrocarbonsr and trace methanol, was recycled to the reactor as the recycle portion, referred to above, from the additional distillation column.
The distillation residue, withdrawn from the bottom of the column, contained 35.~5% MTBE, 36.48% TAME, trace methanol, balance C5 and C6 hydrocarbons including only 2 54%
etherifiable C5 hydrocarbons ~isoamylenes), and was eminently suitable as a high octane blending component for blending into gasollne. The overall conversion to TAME of isoamylenes in the fresh feed, with the additional processing of 30% of the residue from the irst distillation as thus descîibed, was substantially ~15!o~ A proport.i.orl of su~stclntially 71% of the isobu-tylene in the fresh ~eed was converted to MTBE at the same time, with no recycle of any siynificant proportlon of C4 hydrocarbons from the raffirlate.
Numerous advantages over the prior art are achieved by use of the present invention. The known method of removing unreacted methanol ~rom etherification effluent by water washing requires preliminary distlllation to separate and recover the ethers, which have significant solubility in water and could, to a considerable and unacceptable extent, be lost in the wash water, In the process of the present invention the volatility of the ylycols, relative to the other components, and the miscibility of the glycols with C4 and C5 hydrocarbons are both sufficiently low that there is no significant risk of glycol entrainment ox contamination i.n the predominantly hydrocarbon streams. Thus there need be no concern about glycol contamination of the C4 hydrocarbon stream from -the process when it is to be used in an alkylation unit or a polygas unit. Additionally, with respect to any miscibility of ethers in the glycol layer which, subsequent to contacting etherificati~n e~fluent, normally is recovered by distillation of methanol therefrom, there is no tendency of the glycol to distill azeotropically with any traces of ethers therein because the glycol~ether pairs do not form azeotropes as the water/ether pairs generally do. Hence the more volatile ether can fractionallv distill from the glycol along with methanol for recycle to an etherification ~ lS ~
unit and avoid causing any yield loss. Furthermore, the presence of glycol in an etherification step i~ not detri.menta]. to the operation of that process, whereas the presence of any water which might be entrained in methanol being recycled to an etheri:Eication step would be detrimental to the etherification reactor operation. The .low tolerance for water in hydrocarbon feed streams for HF alkylation processes generally requixes that such feed streams be dried, e.g~ with molecular sieves, and a preliminary water washing of such a feed stream would obviously requ.ire a subsequent drying step before HF alkylation~ The use of glycol in the present invention precludes any need for drying I-IF alkylation feed streams with molecular sieves~ Ris]c of corrosion by wet HF in such alkylations also is reduced by use of glycol ln accordance with the present invention.
It will be recognized that numerous modifications may be incorpoxated within the process just described without departing from the spirit or scope of the invention, which is defined in the following claims.
to a fractional distillation column 18 equipped with a condenser 19 and a reboiler 20. This column is operated to separate the ethers and the higher boiling part of the hydro-carbons through the bottom of the column via line 21 and themore volatile predominantly five carbon atom hydrocarbons, includiny the isoamylenes, which dist:ill thxough the top of the column, via line 22. Line 22 condllcts this more volati.le fraction back to reactor 3 where t.he isoamylenes in the fraction are again subject to etherification alon~ with the hydrocarbon feed stream from line 1, The proportion of the residue stream 17 from column 13 which is passed through line 17A for recycle processing can vary between zero and 100 percent of the stream. When none of the stream is taken, the process of the invention acllieves only single pass conversion to TAME of the isoamylenes in the feed which~ with the excellent single pass conversion of isobutylene to MT~E that can be achieved r may be suficient to provide the desired ~8SgL7 octane improvement of the feed stream, particularly in combination with the aclditional octane improvement that can be obtained by the alkylation or other treatment of the stream of hydrocarbons of preclominantly four carbon a~oms recovered from line 16. When 100~ of the residue stream 17 from column 13 is directed through line 17A, the ether containing residue from the bottom of column 13 is all subjected to a fractional distillation which requires significant quantities of heat, the cost of which may not be warranted for the incremental increase in octane which is achieved by such a high degree of recycling. It is more expedient therefore to recycle considerably less than the total amount of the residue stream 17 from column 13, and a preferred proportion for recycle through line 17A is between 10% and 85~ of the residue stream 17 and more preferrably between 15% and 40~ of said stream.
When a recycle portion is withdrawn through line 17~ and fractionall~v distilled in column 18, the higher boiling, ether containing bottom fraction wi~hdrawn through line 21 is a superior octane component for gasoline blending.
2~ ~he glycol contacting unit for removal of methanol from the effluent stream of the etherification reactor, as referred to above, may be either a liquid-liquid type or a vapor absorber type, but preferrably is of the liquid-liquid type, most preferrably the counter-current liquid-liquid type. The vapor absorber type of contacting unit requires that the etherification reactor effluent all he vaporized before passing to the contacting unit, which incrèases the ~emoval costs, therefore liquid--liquid extraction UIlitS are 5~
pre.erre~d, a~ th~ are genera.lly at least as efficient as the vapor absorber type of corltacting unit. The liquid glycol stream which i.s used to contact the reactor effluent stream for extraction of methanol therefrom can be a single li~uid glycol or a mixture of liquid glycols, for example ethylene glycol, diethylene glycol, trieth~lene glycoll propylene glycol, and mixtures of any of these. The essential property of the liquid glycol i.n the extracti.on unit is its ability, as a separate phase, to absorb or extract substantially all of the methanol from the effluent and leave substantiall.y all the dialkyl ethers in admixture with the hydrocarbons of the effluent for blending into gasoline~ The simple (mono)ethylene glycol is the best and most preferred, as it combines optimum properties of extractant for methanol and low miscibil.ity with MTBE and TAME. Di- and triethylene glycols are operable but less preferred because of lower solubility for methanol and increased miscibility with MTBE and TAME.
The temperature at which the methanol removal ; unit is operated generally is lower when using liquid-liquid extraction ~han when using a gas absorber type of unit. In either case it generall.y is in the range from lO~F (-12C) to 450F (232C) and with the pre~erred liquid-liquid extraction units it~is preferrably in the r.ange from 50F to 150F (10C
to 650Cj. The mole flow rate of glycol~ in proportion to the mole flow rate o eff].uent in the contactlng unit, may be in the range from 0.10 to 4.0; preferrabl~ it is in the range from 0.20 to 0.70.
r~ 9 ~-35~7 C'onventional con~ercial eclui.pment for conventional gas absorpti.on or li.quid~liquid extraction operations is suitable for the mei:hanol removal unit required in the present invention. In particular, both packed and pla-te type vapor-li~uid contacting columns are suitable for gas absorption if desired, and likewise either type of column can be used for liquid-liquid extraction. Additionally, other types of mechanical liquid-liquid contactors e.g. rotating disk contactors, can be used. Both counter-current and co-current liquid-liquid extractors are suitable, wi-th the more efficient counter-current type being preferred.
The invention may be more readily unders-tood from the followi.ng specific examples thereof which are given for illustration only and not to limit the following claims~ The proportions given therein and throughout the specification and claims are proportions by weight unless otherwise specifically indi.cated.
EX~MPLE 1 An olefi.nic mixed hydrocarbon stream of hydro-carbons of predominantly four and five carbon atoms was separated from the products of a catalyti.c cracklng operation, principally by fractional distillation; chromatographic analysis of the stream established that its composition was made up of 53.5~ of four carbon atom hydrocarbons including 7.5% C4 reactable with methanol to form ether (i.e. isobutylene) and 46.0~ unreactable C4'sr 39.5% of five carbon atom hydro carbons i~cluding 16.7% C5's reactable with methanol to form -- 10 ~
ether (i.e. isoamylenes) and 22.8~ unreacta~le C5ls, and 7 of six carbon atom hydrocarbons (considered unreactable), This stream was fed continuously, together with a stream of methanol, into a tubular reactor packed with "Ionac C-252"
(Trademark) commercial ion e~change resin in the acid form, used as an etherification catalyst; the molar ratio of methanol to total reactable C4 and C5 hydrocarbons in the reactor feed was maintained at 1.30. The total flow of feed to the reactor provided a liquid hourly space velocity in the reactor of 2.5. Pressure in the reactor was maintained around 13.6 atmospheres and temperature of the feed to the reactor at 160F (71~C). Average temperature across the reactor during the exothermic reaction therein was 184F
(84C). The etherification reactor effluent contained 6.5%
methanol, which could not be adequately separated from the other components of the effluent by fractional distillation.
The effluent was fed continuously, at a rate of 5.3 lb. moles per hour, to the bottom o a continuous counter-current packed ~ed extraction column, 2 inches (5 cm) in diameter and 14 feet (4 3 m~ high, maintained at a pressure of 3.8 atmospheres. A counter~current stream of ethylene glycol at a temperature of 72F (22C) was fed to the top of the extraction column at a mole ratio of 0~45 in proportion to the feed to the bottom of the column. Extracted effluent (raffinate~, withdrawn from the top of the column, was found to contain 10 mole ppm of methan~l and was passed to the middle of a two-inch (5 cm~ diameter distillation sieve tray colu~l having 30 ~ray~. A distillate fraction of hydrocarbons o~ predomiIlcln-Lly our carbon atoms ;~as obtained rom the top of this column and was su~stant~ally free (less than lO mole ppm or 5 weight ppm) of methanol and eminently suitable as feed for either an alkylation process or a polymeriæation proces~ for production of high octane components for yasoline blending. The residue fraction withdrawn continuously from the bottom of the distillation column was a high octane component for gasoline blending and upon analyses by gas chromatography was found to have the following composition:
C~mp~nent Weight Unreactable C4's 2,05 Reactable C4's n . 04 Unreactable C5's51.14 Reactable C5's 14,86 lS C6 ~Iydrocarbons 6.70 Methanol 0,0005 M.T.B.E. 12~90 T.A.M.E. 12.30 The proportions of reactable C4 and C5 hydrocarbons in the original feed stream that were converted to ethers and recovered in this blendiny component were 70~ and 32%
respectively in this sinyle pass reaction. The ethylene glycol extract withdrawn from the bottom of the extraction column was found to contain 7.8% methanol and was fed to a packed stripping column in which the methanol was stripped from the ylycol and recycled to the etherification reactor;
stripped ethylene glycol containiny 150 ppm methanol was recycled from the bottom o the strippiny column to the top of the extraction column for urther extraction of methanol.
3S~7 ~Y~PLE 2 ~ n olefinic rnixed hydrocarbon stream of origin similar ~o that of ~he hydrocar~on mixture used as feed in the previous example was used as raw material in this example and had the following proximate composition: 45.8% C4 hydro-carbons, including 7.9~ isobutylene and 37.9% C4 h~drocarbons unreactable for MTB~ production, 48.8% C5 hydrocarbons including 16.5~ isoamylenes and 32,2% C5 hydrocarbons unreactable to form TAME, and 5~5~ C~ hydrocarbons ~considered unreactable). Utilizing the apparatus used in Example 1 and additionally a 25-plat:e sieve tray fractional distillation column two inches in diameter, with its associated condenser and reboiler, the apparatus was arran~ed as shown diagrammatically in the accompanying drawing with the additional column used for fractionation of a recycle stream. The olefin.ic hydro-carbon stream was fed continuously to the reactor together with a recycle portion obtai.ned as a dist.illate from the top of the foregoing additional sieve tray column; the recycle stream is fuxther identified later herein~ Simultaneously a stream of methanol was fed to the xeactor in a molar ratio of 0.91 relative to the reactable C4 and C5 hydrocarbons in the total reactor feèd. The total reactor feed rate produced an LHSV of 2.0 in the reactor r and the average temperature across the reactor was 180F (82C). Pressure in the reactor was maintained around 13.6 atmospheres. Effluent from the etherification reactor was extracted by a counter~current stream of ethylene glycol in the same manner as in Example 1, and the raffinate dist.illed as in Example 1, to provide a di~s-tillate of mixed ~ 13 ~
a~
prcdominantly C'4 hydrocarbons suhst~ntially free of methanol (less than 10 mole ppm) and suitahle as feed for high octane alkylate or polygas production. A proportion of 30% of the residue from this first distillation was passed to the additional distillation column referred to above, whe.rein it was fractionated to provide a hydrocarbon distillate of pre-dominantly five carbon atom hydrocarbons and a high octane residue containing MTBE and TA~lE formed in the reactor, along with the less volatile of the C5 hydrocarbons and any hi.gher boiliny hydrocarbons in the feed. The remaining 70% of the residue from the irst distillation was a hish octane blending - component suitable for blending directly into a gasoline pool.
Fractionation in this additional distillation column was controlled to remove, in the distillate, most of the etherifiable C5 hydrocarbons (isoamylenes) fed into the column from the preceding distillat:Lon. This distillate, which contained 1.76~ C~ hydrocarbons, 97,23% C5 hydrocarbons including 21.70% isoamylenes, 1.53% C~j hydrocarbonsr and trace methanol, was recycled to the reactor as the recycle portion, referred to above, from the additional distillation column.
The distillation residue, withdrawn from the bottom of the column, contained 35.~5% MTBE, 36.48% TAME, trace methanol, balance C5 and C6 hydrocarbons including only 2 54%
etherifiable C5 hydrocarbons ~isoamylenes), and was eminently suitable as a high octane blending component for blending into gasollne. The overall conversion to TAME of isoamylenes in the fresh feed, with the additional processing of 30% of the residue from the irst distillation as thus descîibed, was substantially ~15!o~ A proport.i.orl of su~stclntially 71% of the isobu-tylene in the fresh ~eed was converted to MTBE at the same time, with no recycle of any siynificant proportlon of C4 hydrocarbons from the raffirlate.
Numerous advantages over the prior art are achieved by use of the present invention. The known method of removing unreacted methanol ~rom etherification effluent by water washing requires preliminary distlllation to separate and recover the ethers, which have significant solubility in water and could, to a considerable and unacceptable extent, be lost in the wash water, In the process of the present invention the volatility of the ylycols, relative to the other components, and the miscibility of the glycols with C4 and C5 hydrocarbons are both sufficiently low that there is no significant risk of glycol entrainment ox contamination i.n the predominantly hydrocarbon streams. Thus there need be no concern about glycol contamination of the C4 hydrocarbon stream from -the process when it is to be used in an alkylation unit or a polygas unit. Additionally, with respect to any miscibility of ethers in the glycol layer which, subsequent to contacting etherificati~n e~fluent, normally is recovered by distillation of methanol therefrom, there is no tendency of the glycol to distill azeotropically with any traces of ethers therein because the glycol~ether pairs do not form azeotropes as the water/ether pairs generally do. Hence the more volatile ether can fractionallv distill from the glycol along with methanol for recycle to an etherification ~ lS ~
unit and avoid causing any yield loss. Furthermore, the presence of glycol in an etherification step i~ not detri.menta]. to the operation of that process, whereas the presence of any water which might be entrained in methanol being recycled to an etheri:Eication step would be detrimental to the etherification reactor operation. The .low tolerance for water in hydrocarbon feed streams for HF alkylation processes generally requixes that such feed streams be dried, e.g~ with molecular sieves, and a preliminary water washing of such a feed stream would obviously requ.ire a subsequent drying step before HF alkylation~ The use of glycol in the present invention precludes any need for drying I-IF alkylation feed streams with molecular sieves~ Ris]c of corrosion by wet HF in such alkylations also is reduced by use of glycol ln accordance with the present invention.
It will be recognized that numerous modifications may be incorpoxated within the process just described without departing from the spirit or scope of the invention, which is defined in the following claims.
Claims (10)
1. A method for processing an olefinic hydrocarbon stream consisting essentially of a mixture including both four and five carbon atom etherifiable olefins, for the formation of high octane components for blending into gasoline, said method comprising
1. passing said stream into an etherification reactor with a proportion of methanol under etherifying conditions, to contact an etherification catalyst therein and etherify tertiary olefins in said stream, 2. passing the entire effluent stream from said etherification reactor into a glycol contacting unit and contacting it therein with a stream or liquid glycol to remove methanol from said effluent and reduce the methanol concentration in the effluent stream to no greater than 200 mole ppm in said effluent, 3. separating said effluent stream from said glycol and fractionally distilling the reduced effluent to separate a distillate containing hydrocarbons of predominantly four carbon atoms each and no greater than 200 mole ppm methanol from a higher boiling high octane fraction containing ethers and hydrocarbons of predominantly more than four carbon atoms each.
2. A method as claimed in claim 1 including the additional step of fractionally distilling a proportion of said higher boiling fraction to separate a distillate of hydrocarbons of predominantly five carbon atoms each from a higher boiling ether containing portion, and recycling said distillate of hydrocarbons of predominantly five carbon atoms each as additional feed to said etherification reactor.
3. A method as claimed in claim 1 or 2 and including the additional steps of fractionally distilling the glycol separated from the effluent stream to obtain a distillate of methanol as part of the methanol feed to said etherification reactor and recycling said residue of glycol to said glycol contacting unit as the stream of liquid glycol.
4. A method as claimed in claim 1 or 2 in which the glycol contacting unit is a counter-current liquid-liquid extractor.
5. A method as claimed in claim 1 or 2 in which the glycol is ethylene glycol.
6. A method as claimed in claim 1 in which the glycol is ethylene glycol which contacts the effluent in a mole ratio of glycol to effluent in the range from 0.1 to 4Ø
7. A method as claimed in claim 6 in which the mole ratio is in the range from 0.20 to 0.70.
8. A method as claimed in claim 2, in which the proportion of the said higher boiling fraction which is additionally fractionally distilled is a proportion in the range between 10% and 85% of said fraction.
9. A method as claimed in claim 8 in which the proportion is between 15% and 40%.
10. In a method of processing an olefinic hydrocarbon mixture including both four and five carbon atom etherifiable hydrocarbons, for the formation of high octane components for blending into gasoline, in which the mixture is reacted with methanol under etherifying conditions to etherify tertiary olefins therein and unreacted hydrocarbons of four carbon atoms are distilled from the etherified mixture for subsequent catalytic processing, the improvement which consists in contacting the etherified mixture containing unreacted methanol with an immiscible liquid glycol phase to remove methanol from the etherified mixture and reduce the methanol concentration in the mixture to no greater than 200 mole ppm, and subsequently separating the glycol phase containing the removed methanol from the etherified mixture before unreacted hydrocarbons of four carbon atoms are distilled from the etherified mixture.
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA312,338A CA1098547A (en) | 1978-09-28 | 1978-09-28 | Etherification processing of light hydrocarbons |
| GB7932005A GB2031886B (en) | 1978-09-28 | 1979-09-14 | Etherification processing of light hydrocarbons |
| IT25952/79A IT1123304B (en) | 1978-09-28 | 1979-09-25 | PROCEDURE FOR THE ETERIFICATION OF LIGHT HYDROCARBONS |
| DE19792938738 DE2938738A1 (en) | 1978-09-28 | 1979-09-25 | METHOD FOR PROCESSING OLEFINIC HYDROCARBON MIXTURES |
| NL7907171A NL7907171A (en) | 1978-09-28 | 1979-09-26 | PROCESS FOR THE ETERNATION OF LIGHT HYDROCARBONS. |
| FR7923911A FR2437389A1 (en) | 1978-09-28 | 1979-09-26 | IMPROVEMENT FOR THE TREATMENT OF LIGHT HYDROCARBON ETHERIFICATION |
| JP12330379A JPS5548285A (en) | 1978-09-28 | 1979-09-27 | Improvement of light hydrocarbon etherifying treatment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA312,338A CA1098547A (en) | 1978-09-28 | 1978-09-28 | Etherification processing of light hydrocarbons |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1098547A true CA1098547A (en) | 1981-03-31 |
Family
ID=4112484
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA312,338A Expired CA1098547A (en) | 1978-09-28 | 1978-09-28 | Etherification processing of light hydrocarbons |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS5548285A (en) |
| CA (1) | CA1098547A (en) |
| DE (1) | DE2938738A1 (en) |
| FR (1) | FR2437389A1 (en) |
| GB (1) | GB2031886B (en) |
| IT (1) | IT1123304B (en) |
| NL (1) | NL7907171A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55169336U (en) * | 1979-05-22 | 1980-12-05 |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1089881A (en) * | 1978-03-10 | 1980-11-18 | Gulf Canada Limited | Method for processing etherified light hydrocarbon mixtures to remove methanol |
| FR2465699A1 (en) * | 1979-09-19 | 1981-03-27 | Gulf Canada Ltd | Etherification of isobutylene in light gasoline fractions - with removal of unreacted methanol by contact with glycol |
-
1978
- 1978-09-28 CA CA312,338A patent/CA1098547A/en not_active Expired
-
1979
- 1979-09-14 GB GB7932005A patent/GB2031886B/en not_active Expired
- 1979-09-25 IT IT25952/79A patent/IT1123304B/en active
- 1979-09-25 DE DE19792938738 patent/DE2938738A1/en not_active Ceased
- 1979-09-26 NL NL7907171A patent/NL7907171A/en not_active Application Discontinuation
- 1979-09-26 FR FR7923911A patent/FR2437389A1/en active Granted
- 1979-09-27 JP JP12330379A patent/JPS5548285A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| GB2031886A (en) | 1980-04-30 |
| IT1123304B (en) | 1986-04-30 |
| NL7907171A (en) | 1980-04-01 |
| IT7925952A0 (en) | 1979-09-25 |
| FR2437389A1 (en) | 1980-04-25 |
| DE2938738A1 (en) | 1980-04-10 |
| JPS5548285A (en) | 1980-04-05 |
| FR2437389B1 (en) | 1984-04-20 |
| GB2031886B (en) | 1982-11-10 |
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