US2534025A - Production of aviation or motor fuels - Google Patents

Description

Dec. 12, 195o D. A. HowI-:s ETAL PRODUCTION OF AVIATION Oa MOIOR FUELS Filed Dec.

lvnm' Pond/a fber Howes Thomas 7.6/2"

'y 5 dtg'neys EQ WEWQQQQ Patented Dec. 12, 19950 UNITED `STATES BFENT y OFFCE PRODUCTION OF AVIATION OR'MOTOR.

FUELS 4 Donald A. Howes and Thomas Tait, Sunbury-on- Thames, England, assignors t Anglo-Iranian Oil Company Limited, London, England, a British joint-stock corporation Application December 15, 1948, Serial N0. 65,468

In Great Britain May 5, 19541 l i0 claims. (o1. 19e-7s) o The invention relates to the production of high ade aviation or motor fuels or motor fuel coni ituents. More particularlythe invention relates to the production of high grade motor fuel fromAv ieedstocks containing appreciable proportions of tillates that appreciable quantities of stable high grade aviaion spirit may be obtained from them. The invention is not limited to any particular nod oiproducing the feedstock. The cracked dist ate subjected to the process of the invention may for example'be obtained from a crude stock and comprise any fraction derived from a crude mineral oil ranging from naphtha to heavy residuum. Particularly good results are obtained however in the use as feedstocks of cracked distillates obtained in thermal reforming operations,

in which the feedstocks are those generally known asnaphthas having a boiling range approxiniating '70 C.-300 C. The thermal reformingconditions usually vemployed in such cases vary as'to'temperature between 480 C. and 700 C. and as to pressure between 100 and 2,000 lbs.'

per square inch. The condensible gases formed in the process, being Ca and Ci hydrocarbons may be recycled to thecracking still and mixed with the naptha feed. In generalthe cracked distillate so produced will have an octane number (C. F. R. Motor Method) of from 65 to as high as 90 or even higher, according to the character or composition of the naptha processed and the reforming conditions employed. In the nature of the case products of higher octane number re- V'quire the use of more drastic conditions of reforming in the use of higher temperatures in the ranges.

According to the invention a feedstock containing mono-olenes and/or di-olefines, such as the cracked distillates referred to, is submitted to hydrogenation to convert the mono-olefines and/or di-olefines into the corresponding paraiiin or naphthene hydrocarbons, and the treated material including the saturated products Yare thereupon fractionated for the separation of hydrocarbons or fractions of low` octane member consisting mainly of the normal parains and simple branched* chain paraffins of low octane number, and for the recovery of hydrocarbons or fractions of. high octane` number consisting mainly` of lyst per hour.

naphthene hydrocarbons and branched 'chain'. paraffin hydrocarbons of high octane number;` under the conditions hereinafter more particular-57 ly described;`and the hydrocarbons or fractions" of high octane number recovered may be blend-A ed together, and with hydrocarbons suchua's: toluene, Xylene-and higher aromatic hydrocar-jv bons recovered in known manner as by solvent extraction `from the recovered hydrogenated' product or a fraction thereof. The high octane number hydrocarbons or fractions may be used` individually or together in Varying proportions as constituents of a high grade motor or aviation' fuel. i f

The` feedstock may be first desulphurized or may be desulphurized under the conditions of hydro:l genation. The preliminary desulphurization 'is howeveronly. necessary if the feedstock contains -3 proportion of sulphur compounds injurious to hydrogenation catalyst employed.

'The invention comprises the. process` conditions.

hereinafter. described.

ln carrying the invention into effect the hydrogenation treatment may be carried 4out .on a. cracked distillate having for example a final boiling point of 200 C. to 300'C. at a temperature within the range 'C. to 300 C. and at agspac'ef velocity of 0.5 to 5.0 volumes per volume of cata: Hydrogen is advantageously einployed in excess, and the hydrogenating catalyst may conveniently consist of or contain a mixture of tungsten and nickel sulphides, or cobalt molybdate or nickel molybdate or reduced iron oxide or a mixture of alumina and nickeloxide; The hydrogenated product may ordinarily contain a small quantity of hydrogen sulphide' in solution, which may be removed by washing' the hydrogenated product with an alkaline solution such as a solution of caustic soda. The Vmonoolenes and/or d-.olenes of the feedstock 'are convertedunder the conditions of treatmentinto' the corresponding paraffin and naphthene hydro'i earbons by simple addition of hydrogen.unaci coinpanied by any substantial formation 'ofhyI drocarbons of lower molecular Weight. l j

Where the feedstock has a sulphur content injurious to the catalyst that may be employed for its hydogenation, `the feedstock may be drst subjected to treatment for. thesubstantial removal of the sulphur compounds. Hydrogenation 'cata-1 lysts are aifected'in a varying degree by the presi ence of sulphur'compounds. Thus simple reduced nickel catalysts are rapidly poisoned by very small amounts of sulphur compounds,A for example` 0.01% or less, while mixtures of tungsten *andV at a temperature within the range '530' C. to

'700 C., and at a throughput of" from 0.5 `to I0. liquid volumes per volume of catalyst per hour, in the absence of hydrogen. -llllternativelyfdesul'` -fphurizing catalysts comprising mixtures of molybdic oxide and alumina, or chromic oxide andv lalumina may be employedunder the same re-V action conditions, but in the. presence of added hydrogen., In this` manner the sulphur content of the, cracked distillate may be reduced from for example 0.1% to less than 0.001%'.

The hydrogenated product may then be fractionated under conditions of precision in fractionation determined to insure control of top and bottom temperatures, reflux.` ratios` and pressures inthe fractionating columns and vin thev use of the. equivalent of' 50 or more theoretical plates,

whereby thev normal paraffin hydrocarbons or fractions rich in such constituents are removed. SuchV normal,` hydrocarbons. present in the feed'- stock or Vformed during the treatment that results in the simple saturationof straight chain olene hydrocarbons, are of. low` octane number,

as indicated by the following gures:

Octane number (C. EUR.. Motor) Normal pentarre.. .'c 61 Normal hexane 25 Normal heptane Normal octane 17 Normal nomme 45 Their removal thus results inamarked increase A' in thei octane number of, such hydrocarbons or fractionsrecovered;

'The hydrogenated product may be fractionated to form a lighter anda heavier' fraction and that part. ofthe hydrogenated! product, boiling above about` 100 C. may be treated with a selective solventv for Vthe recovery ofaromatic hydrocarbons. such as toluene, xylene, ethylr benzene and higher aromatic hydrocarbons. For Vthis purpose liquid sulphur dioxideY may advantageously be. used and the treatment carried out in known manner at a low temperature of'from 10"0. to -80 C., whereby theY aromatic hydrocarbons are recoveredA in a high concentration.V The lighter fraction may be fractionated Vunder the condimay. have been recovered from that. part of the hydrogenated product boiling up to 100 C. and

from which the normal parallins or fractions rich 4 in normal parains have been removed in the manner under the conditions described.Y

The invention is diagrammatically illustrated by way of example in the accompanying drawing.

In carrying the invention into effect as illusV trated in the accompanying drawing a feedstock, such, for example, as a distillate produced in the thermal cracking or thermal reforming operation is desul-phurized under known conditions such as hereinbefore described in a preliminary treatment stage 7c if it contains an appreciable proportion of sulphur, and is thereupon hydrogenated in a known manner in asucceeding stage l under conditions such as hereinbefore described for the conversion of the mono-olene and di-clene content, into corresponding paraffin and naphchene-hydrocarbons.

The hydrogenated product is then fractionated in a fractionator L to obtain a light fraction as an overhead product and a heavier fraction as a Y bottoms product. Y

The bottoms product of the fractionator- L,

which may advantageously be that part of the hydrogenated product boiling above C., is passed for solventextraction or its aromatic hydrocarbon content through the solvent extraction andfseparating plant m, which operates in known manner, the materialv flowing successively lirst into a mixingtank in which itis contacted with liquid sulphurv dioxide under known conditions, whereuponA the mixture passes into a settling tankfor'the settlement andI separation of the extract and ralnnate phases; The aromatic extract thence passes asreed to a' column for the removal of the liquid sulphur dioxideasoverhead and the aromatic extract as bottoms, which latter may.' pass to storage for'eventual use of the material asa fuel blending constituent inthe proportions'that maybe stipulated-byfuel specifications, while the railinate passes as feed to a column Where the sulphur Vdioxide is separated and the ralhnate passes' to storage.

' The overhead: product. of the'fractionator L is passedto the first of a series offractionating col'- umns. a, IJ, c', d' ande for the separation under conditions of` precision in fractionation of0 hydroc arbons or fractions consisting mainly or they normal paramos VandV simple branched chain parafns oil low'octane numbenan'diforthe recoveryof Vhydrocarbons or fractions of high octane number consisting mainly ofV naphthene hydrocarbons and branched `chain paraihn hydrocarbons of high octane number. Y

Each ci the columns is vprovided for example withY the equivalentiofa moderately large number of theoretical plates not substantially less than 50 theoretical plates and a moderate redux ratio maintained in operation 'of the columns for example of. 15 1,V and'` top and bottom temperatures maintained in the. columns under control by analysis and the use oilaboratory equipment and a moderate pressure applied in the column in which isopentane is recovered,'whereby the operating conditions may be precisely controlled in the respective columns having regard to the determinations thus madeV as to composition.V

The temperature conditions are determined in the columns such that an isopentane fraction is recovered in the column a as overhead from normal pentane and higher hydrocarbons which leave as bottoms. The latter thence passes into the column b ata mid-position in its length where the operating conditions are so determined that normalpentane is4 separated` as overhead and higher hydrocarbons' leave as bottoms. The latter' then passes to a mid-position in the column' c in which an iso-hexane fraction is recovered as overhead having an approximate boiling range of 45-64 C. including cyclopentane and the'four hexane isomers to the substantial exclusion of normal hexane which leaves thev columnA c with the higher hydrocarbons as bottoms, to enter. the next column d at a mid-position, where the. normal hexane fraction is separated as overhead and the remainder as bottoms. The latter then passes in a mid-position to the column e, where at a moderate redux ratio of approximately :1 a recoveryof ran isoheptane fraction is made as overhead, having the approximate boiling range of 72-92 C. comprising the content of cyclic hydrocarbons and branched chain hydrocarbons boiling in that range to the exclusion of any substantial proportion of 2-methyl hexane, S-methyl hexane; S-ethyl pentane and normal heptane which leaves the lcolumn e through the pipe 3 together with the hydrocarbons boiling beyond that range. s

The high grade overhead fractions from the columns a, c and e pass by the respective lines ai, c1 and e1 to the respective storage vessels a2, c2, and e2 whence they may be withdrawn as blending constituents for use with the aromatic extract hereinbefore described in the proportions that may be stipulated by fuel specifications.

The normal pentane and normal hexane fractions leaving as overhead respectively from the columns b and d may pass by the pipe line b1 to storage.

It will be understood that the extentof fractionation will depend upon the initial boiling point of' the feedstock. Thus according to its composition, the feedstock may only require frac- -tionationin the columns b, c, d and e or other smaller number of columns according to its content of normal parafn hydrocarbons and of its content of isopentane and of the isohexane and iso-heptane fractions.

This application is a continuation-in-part of our copending application, Serial Number 444,260, filed May 23, 1942, and now abandoned, for Improvernents relating to the production of aviation or motor fuels.

What is claimed is:

1. A process for the production of blending constituents of an aviation or motor fuel of high octane number from a substantially sulphur-free cracked petroleum distillate containing monoolefines and di-oleflnes, comprising subjecting the sulphur-free feedstock to hydrogenation for the conversion of the mono-olefine and di-oleflne con- L tent into corresponding paraflin and naphthene hydrocarbons by simple addition of hydrogen, separating the hydrogenated cracked distillate into a lighter fraction boiling up to about 100 C. and into a heavier fraction,'subjecting said lighter fraction of the hydrogenated cracked distillate to fractionation for the separation therefrom of at least one normal fraction, namely normal heptane together with the content of said lighter fraction boiling beyond about 92 C. and for the recovery from said lighter fraction of at least one fraction of high octane number, namely a fraction having an approximate boiling range of about 72 C`. to about 92 C. comprising the content of cyclic hydrocarbons and branched chain hydrocarbons boiling in that range to the exclusion of any substantial proportion o-f 2-methyl hexane, S-methyl hexane, 3-ethy1 pentane and normal heptane, the fractionations being carried out under conditions of precision in the main tenance of determined top and bottom tempera-7 tures and pressure, in theV use of columns having the equivalent of a moderately large` number of theoretical plates not substantially less than 50 theoretical plates, and a high reflux ratio, in gen.- eral not substantially less than 15:1, and subjecting the said heavier fraction of the hydrogenated cracked distillate boiling beyond about C. to solvent extraction for the recovery from said heavier fraction of an aromatic hydrocarbon extract as an additional blending constituent.

2. A process as specified in claim 1, in which the material fed to the columns is analyzed. and the operating conditions precisely controlled in the columns having regard to the determinations made. A

3. A process for the production of blending constituents of an aviation or motor fuel of high octane number from a cracked petroleum distillate as specified in claim 1, in which the said lighter fraction of the hydrogenated ycracked distillate before being fractionated for the separation of normal heptane, is fractionated under the same conditions of precision in fractionation for the recovery of a fraction of high octane number having approximately a boiling range of 45-64 C. comprising substantially the content in the hydrogenated cracked distillate, of cyclopentane together with the dimethyl butanes and the methyl pentanes boilingin that range as an 'additional blending constituent.

4. A process for the production of blending constituents of `an aviation or motor fuel of high octane number from a cracked petroleum .distillate as specified in claim 1, in which said lighter fraction of the hydrogenated cracked distillate before being fractionated for the separation of normal heptane, is fractionated under the same conditions of precision in fractionation for the recovery of a fraction of high octane number having approximately a boiling range of 45-64 C. comprising substantially the content in the hydrogenated cracked distillate, or cyclopentane together With the dimethyl butanes and the methyl pentanes boiling in that range as an additional blending constituent and in which theI material fed to the columns is analyzed, and the operating conditions precisely controlled in the columns having regard to the determinations made.

5. A process for the production of blending constituents of an aviation or motor fuel of high octane number from a cracked petroleum distillate as specified in claim 1, in which the said lighter fraction of the hydrogenated cracked distillate before being fractionated for the separation of normal heptane is fractionated under the same conditions of precision in fractionation for the separation of normal pentane, for the recovery of an additional fraction of high octane number having approximately a boiling range of 45-64 C., comprising substantiallyl the content in the distillate of cyclopentane together with the di-methyl butanes and the methyl pentanes boiling in that range, as a blending constituent, and for the recovery of the content of isopentane, as a blending constituent.

6. A process for the production of' blending constituents of an aviation or motor fuel of high octane number from a cracked petroleum distillate as specified in claim 1, in which said lighter fraction of the hydrogenated cracked distillate before being fractionated for the separation of normal heptane is fractionated under the same conditions of precision in fractionation, for the separation of normal pentane and normal :fhexa'ne,' for the recovery vof a zfraction of high -octane number :having approximately Vla boilinef"Y range of l5i-64 iC.. comprising substanf tially ithe content in ithe distillate of :cyclopene tane Itoge'ther with vthe diemethy'l :bu'tanes :and the methyl `pentanes `boiling 'inthatqranges as :a `blending constituent, and fior thel recoveryvof thescontent 'of isopentanegas a 'iblendinga constituent, andl in which the. material fed `tothe column is ianalyzed, and `the :operating .zconditions'ypr ciselycontroiled in lthe Acolurmzrshaving regardito the 'determinations made.` i

'7.'.1.,p'1-ocess A'for the production -of blending constituents of fan avation or motor :fuel of :high cctanenumber from a cracked: andhydrogenated distillate asspeciledA in claim 1, in which the V:fraction having 'fa boilingfrange of v72" tofabout v922C.is recovered ina `-column operatingi'atla reflux ratio of substantially 110:1.

28. A A*process for the production-:of `blending l `constituents l of kan laviation or motor fuel -as speciedin claim il, in'whichthescracked disr- `tillatelo'as Ya nal boilingpoint of from 20'0"'C.

"to 300 C.:and is hydrogenated'atxa temperature yinthe lrange 150'C.-'300"'C.and Iatfzaxspace vei; t

klo'city `.of 10.5 yto j5'.0"vo1s. per' vol. of catalystV per hour.

'9. A Aprocess .for the :production `Vof :blending i'constituents of ian aviation or :motor fuel Yas speciied.y in :claim "1, Ain IWhichthe :cracked 'feedstock is hydrogenated in the presence of: hydro- 210, fA process Lior l.the1preduction of .blending Vconstituents Vof an aviation or :zmotor fuel of "high octane number fromY 'asnbstantially sub i phu'r-'free cracked Avpetroleurn `distillate containingmono-olenes vvand diolenes comprisingr the hydrocarbons `by simple '.:additio'n :of lrlylnig'ens:- subjecting :the y,lighter z'portion -of :the` Vihydroggenated .product .boiling up :to 4about ,110,0" IC. to 'fractionation for :the 5*separation itherefrom of "at least one normal iraction, namely normal hep-f .tane :together with ithe .content .of said jlighter portion boiling 1 beyond z about 92 `C. .and for the recovery from said lighter portion `of -at least one -fraction of zl'xighxoctaneinumber, namely a fraction having an Aapproximate thoiling ,range Ycontent `of --cyclic hydrocarbons .and branched fchainhydrocarbons' boi1ing; in thatrange ato the "exclusion-of any ysubstantial proportion of "2,- Y'methyl hexane, -methyl hexane, 3-ethyl apen Etane and lnormal heptane, the fractionation 1be ing carried fout under conditions. of precision` in -the maintenance of `determined top and bottom temperaturesand pressure, inthe .use'of columns having vthe :equivalent of Vfa moderately --large number of theoretical plates vnot -substantiail'y less than 50 theoretical plates, and a highi'eilux AVratio, in general 'notsubstantiallyj lessV than F15 l.

"DONALD A. HOWES. THOMAS-TAH.

REFERENCES curan i Th'ejfollowlne references `areo record `ins-the ille of this patent:

Y UNITEDfsTATEsPATENTS vNumber 'rfName Date 2,055,455 Taylor et a1. Sept. '22,1936

OTHER REFERENCES l? Petroleum Processing, vol. 2,.;No. 21.(Feb., 19471,

vpages 1:36, Y139,.*'14o142,143, .145 and 146 article "by 'lf-Birch, Doeksen fand Dove V'on ,Supe'rfrace nonanonn. -V

Claims (1)

10. A PROCESS FOR THE PRODUCTION OF BLENDING CONSTITUENTS OF AN AVIATION OR MOTOR FUEL OF HIGH OCTANE NUMER FROM A SUBSTANTIALLY SULPHUR-FREE CRACKED PETROLEUM DISTILLATE CONTAINING MONO-OLEFINES AND DIOLEFINES COMPRISING THE STEPS OF HYDROGENATING THE FEEDSTOCK FOR THE CONVERSION OF THE MONO-OLEFINE AND DIOLEFINE CONTENT INTO CORRESPONDING PARAFFIN AND NAPHTHENE HYDROCARBONS BY SIMPLE ADDITION OF HYDROGEN; SUBJECTING THE LIGHTER PORTION OF THE HYDROGENATED PRODUCT BOILING UP TO ABOUT 100*C TO FRACTIONATION FOR THE SEPARATION THEREFROM OF AT LEAST ONE NORMAL FRACTION, NAMELY NORMAL HEPTANE TOGETHER WITH THE CONTENT OF SAID LIGHTER PORTION BOILING BEYOND ABOUT 92*C AND FOR THE RECOVERY FROM SAID LIGHTER PORTION OF AT LEAST ONE FRACTION OF HIGH OCTANE NUMBER, NAMELY A FRACTION HAVING AN APPROXIMATELY BOILING RANGE OF ABOUT 72*C TO ABOUT 92*C COMPRISING THE CONTENT OF CYCLIC HYDROCARBONS AND BRANCHED CHAIN HYDROCARBONS BOILING IN THAT RANGE TO THE EXCLUSION OF ANY SUBSTANTIAL PROPORTION OF 2METHYL HEXANE, 3-METHYL HEXANE, 3-ETHYL PENTANE AND NORMAL HEPTANE, THE FRACTIONATION BEING CARRIED OUT UNDER CONDITIONS OF PRECISION IN THE MAINTENANCE OF DETERMINED TOP AND BOTTOM TEMPERATURES AND PRESSURE, IN TEH USE OF COLUMNS HAVING HE EQUIVALENT OF A MODERATELY LARGE NUMBER OF THEORETICAL PLATES NOT SUBSTANTIALLY LESS THAN 50 THEORETICAL PLATES, AND A HIGH REFLUX RATIO, IN GENERALY NOT SUBSTANTIALLY LESS THAN 15:1.

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