US2009108A - Treatment of hydrocarbon oil - Google Patents

Description

G. EGLOF F TREATMENT OF HYDROCARBON OIL July 23, 1935.

Flled Feb. 8, 1933 5 gW/Q? v Mor/feg Patented July 23,V 1935 Gustav Egloff, Chicago, Ill.,'asslgnor to Universal Oil Products Company, Chicago,` Dlna'jcorporation ofv Delaware 'l application February s, 19.33, saisine. 655,720

This invention relatesv to the treatment of ,hy-f

d rocarbon oils, and refers more particularly to the production of gasolines of superior value by cracking and synthetic reactions applied to the heavier and less valuable portions of crude petroleums and .similar hydrocarbonv mixtures. More specically'the inventionhas reference to a process for improving'I the anti-knock value of gasoline boiling fractions produced by cracking while at the Sametime conserving the'olens which would either be lostzinv the` stabilizing of the gasoline in respect to vapor pressure or with respect to gum-forming tendencies.' However,

Y other important refining eiects are produced during the course of the treatment. l, .A l

The cracking process is quitegenerally lused.

e at the present time tol meet 'the increasing' demands for motor fuel of a high anti-knock character. The superior anti-knock value of cracked gasolines 'compared to straight run gasolines ofV similar' boiling range is apparently due to their higher content of cyclic and unsaturated straight chain hydrocarbons as well as to their content of n tion comprises the cracking of petroleum hydro- 'carbon fractions'to produce vapors of approxiiso-parafns.. The cyclic hydrocarbons Aand the iso-paraflins .are not objectionable from the standpoint of stability, but an excess 'of yoleiins is to be avoided onl account of the tendency of the more highly unsaturated members to polymerze whereby gumsY are formed and theA gasoline is thrown oi color and loses anti-knock value.

The most commonly -used method in reilning cracked naphthas to remove the more undesirable oleinicconstituents whichv are the chief offenders in the matter'oi gum and color formation is to treat in liquid phaseat ordinary temperatures with sulfuric acid of commercial grade and redistill to produces, gasoline .of desired boiling range. Other 'processes which are used to some extent employ halides of the heavy metals such as those of aluminum, zinc, tin,iron, etcetera, and conduct treatments in either liquid or vapor phase. Furthermore, use has been made of adsorbent earths such as fullers earth, clays, bentonitebauxite. etc.,leither alone or in convjunction with various polymerizing metals salts. While all of the treating methodsv thus briefly vrecounted may be used effectively to stabilize and renne cracked naphthas and gasolines, they are all open to the general objection that theyremove compounds whichhave high anti-knock vvalue ,so that llosses are' suiered both in respect to yield and also in respect to quality of product. These losses, may be partlcularlyfseverevin the caseV of sulphuric acid treatments sincethis reagent is employed many times on high sulphur,

cracked naphthas to reduce` their vsulphurfcontent to a permissible point, the amounts' ci acid necessary for this purpose reacting at the same ytime with'the oleflns so that valuable mono-olevi claims.. (crise-10)l l I ilns as rwell as unstabledi-and tri-oleilns are removed. y Thepresent process isl a distinct departure from older and more, generally established methods of treatment in that it converts the more unstable, high anti-knock olefins in cracked naphthas into stable hydrocarbons of increased anti-knock value by synthetic reactions which 'will be disclosed in detail in thefollowing specification.

The cracking process ordinarily practiced also produces 'a substantial amount of low boiling hydrocarbons ofboth an oleflnic and a parafiinic character which are either gaseous at ordinary temperature, and n pressures or if liquids,` "have'too high vapor pressure tov permit their unlimited ,blendingwith' 'gasoline fractions. The

' present processes will be more specifically brought out in later paragraphs, also conserves the greatsure and possessingY high anti-knock character- -istics.

I n one .specinc embodiment the present invenmate Vgasoline boiling range, further controllably reacting the voleilnic components of the vapors with. cyclicr compoundstherein present and with aromatic hydrocarbons added from outside sources in the .presence of metal salts capable of eiecting desired condensation-reactions, sep- The nature yof the inventlonmay be convenl iently developed in connectionk with the description of an operation vcomprised within its scope.

To assist inv this description the attached diagrammatic drawing'has been vprovided which shows by means of conventional ilgures not drawn to scale an arrangement of elements in which the lmay be applied to the vapors from any type of cracking process. In the Yplant shown in the drawinmhowever, vraw oil charging stock may be introduced into theV cracking unit through a line I .containing 'a control valve 2 'and pumped by 'a pump l through a. line 4 containing control valve iinto a fractionator C whose function is to separate substantially all 'off the cracked components `which are Vutilizable as motor fuel. 'Thegcold incoming raw oil contacts'directly with the vapors undergoing fractionation, assisting in the fractol tionating step by its cooling action and Vat the same time being stripped and preheated.

Bottom refluxes from iractionator 6 comprising intermediate insuiiciently converted reflux ccndensates and preheated and topped raw oil may be withdrawn through line 1 containing control valve 8 'and pumped by pump 9 through a combined feed line I containing control valve I'l into and through a heating element I2 of 'suitable design and capacity and disposed to receive heat from a furnace'f. The pressure and temperature obtaining at the exit of the heating element will depend upon the type of raw oil charging stock undergoing conversion andv the yield and quality of product desired in conjunction with the secondary step to be later described. It may, however, be stated that as a rule that in most commercial crackinginstallations the temperature at this point is comprised within the approximate range of 850 to 1000" F., and that pressures of from 100 to 500 pounds per square inch are employed.

The heated products may be transferred through a line il containing a control valve Il to an enlarged vaporizing and reaction zone `I6 in which time is given for the completion of conversion reactions. The residual products accumulating in reaction chamber I6 will vary from liquid to coke depending upon the intensity and extent of cracking conditions, line I1 containing control valve I8 being shown as a means of continuously withdrawing liquid residue if mildv valve 20 and enter a fractionator i previouslyr mentioned, vapors of approximate gasoline bolling range being evolved through line 2l and con- 'trol valve 22. Fractionator 0 may be operated at substantially the same pressure as that used :in reaction chamber I6 ormay be operated under reduced pressure, as desired.

The vaporous materials passing through line 2i will consist of both xed gases and oil vapors and will comprise members of the olenic, paraffinic, naphthenic and aromatic series of hydrocarbons, though thepercentage of the last named group will be small unless conditions of great severity have been employed in the preceding heating and reaction zone. lCraclredvapors thus produced practically always contain the lower.

members of the oleflnic or ethylene series of hydrocarbons suolias ethylene, propylene, butylenes, amylenes, etc. 'Owing to the increasing.

number of possible isomers in oleflns containing four or more carbon atoms, the positive identication of olefin compounds in the liquid gasoline fractions from cracking .is very dlllicult. However, approximate analyses using reac ivity with oxygen, sulphuric acid and halogens asa basis for estimating indicates 'that a large per-A may be introduced into the vapor stream in regulated quantity from a source of supply not shown by way of a line 23 containing control valve 2l, a Vpump 25 and line 26 containing control valve 21 and joining with line 2|. A

Reactions of combination between olefins and cyclic compounds, particularly aromatics. are brought about in a treater 28 which preferably contains a stationary contact mass comprising a metal lhalide having catalytic properties, such a mass being formed, for example by impregnating a silicious carrier with such salts as anhydrous aluminum chlorideor commercial zinc chloride. Suilicient condensing action may sometimes be obtained by merely employing an adsorbent earth such as a fullersvearth or a bentonite clay of proper particle si to expose a suiilcient amount of active surface without introducing too great resistance to the flow of the vapors. The solid contact masses maybe supported upon screens or perforated false bottoms which are not shownir-i the drawing. A considerable number of simple or' compound catalyst mixtures may be used alternatively in the treater, but obviously each will accelerate the condensation reactions to a degree depending upon its ownpeculiar composition and not be identical nor equivalent in its action to the other alternative catalysts which may be employed.

The following equation shows a typical reaction which occurs between a low boiling oleiln and an aromatic to produce an alkylated aromatic which has thehigh anti-knock characteristics already alluded to in previous paragraphs:

Catalyst Y v CaHa 'i' CeHo CoHs'CxH Propylene Benzol Iso-propyl benzol The mono derivative formed represents the primary stage of alkylation. Evidently the formation of poly-substituted compounds occurs to some extent in all cases though the formation of such compounds as are not utilizable in gasoline may be4 minimized, by proper control of operating con- .mixture is subjected to the action of condensing catalysts is of the type represented by the above equation, a varying amount of polymerization among oleflns'is unavoidable. However, it is apparent from experiments that the polymers thus formedrare substantially no higher than dior tri-molecular so thatV they are still utilizable as constituents of motor fuel and do not then possess gummy or resinous characteristics of the higher polymers. f

,The dimers of propylene, butylenes, amylenes and hexylenes all boil within the range of commercial gasoline, that is, below 437 F. Apparently polymers thus formed are of an iso or branched chain character which possess greater anti-knock value than the corresponding hydrocarbons of normal structure. y

While pure aromatics such as benzol may be introduced into the cracked vapors for the purpose described, it is not necessary that such compounds be chemically pure or even freed from gum-forming compounds by previous chemical or catalytic treatment. The light oil `distillates produced in coal or shale distillation may be added at this point Ysince these distillates contain large quantitles of aromatics such as benzol, toluol and the xylols, Obviously, the proportioning of thearomatics and oleilns toobtain theV best results will depend juponj the type and characteroi olens present thoughY in lieu. of extended analysesithe proportions may bey determined by a iewtrials withproper sampling andtestingof the products. Only moderate temperatures and pressures are :y necessary in treater 28. In conductingcondensain the case of treatments conducted Vwith alutions of the type expressed by the'previous equation given good results are obtainable without employing temperatures much Aabove atmospheric, y

say, those in the neighborhood of 104 to 122 F., Y

when aluminum chloride, 'for example, is used as a condensing catalyst.r `The mean boilingtemfV peratureof cracked vapors of approximate gasoline boiling range vwill b e-v approximately 350 'to 400 F., with `pressures of from 50`to 100 pounds per `square* inch` .Under f such circumstances only relatively mild condensing agents such as zinc chlorideor even fullers Aearth alone maybe needed towefiect the desired synthesis.. It is comprised within the scope of the invention if necessary, to cool and Ipartly condensesome o! the heavier portions of the vapors prior to their subjection to. catalytic action though means for this purpose are not shown in the drawing. Obviously,

i1 liquidaromatics are injected into the' vaporlineV as shown there will be some cooling and attendant liqueiactiom` However, such does not' militate against the success of the treatment since good `results are obtainedby 'contacting the Y` lighter vapors and gases with liquid aromatics if the liquids are eflectivelyidistributed over the catalyst or spacing material which acts as a i'lller in the treater. f 'Y I When treatments are conducted atl normal wvapor temperatures'so thatsubstantiallyfno condensation' of gasoline boiling range products occurs the vapors maygthen be passed through line 45 containing control valve 46 into a fractionator 41fwhich'is of'a designand'capacity suitable forl i'ractionator 4l through lineA 4B containing control valve 49 and they may be retreated to produce further quantities of motor fuel by being returned to the conversion zone of the cracking plant.

It is within the scope of the invention to em- -ploy concentrated solutions of metal halides effective in producing condensation reactions between olens and cyclic hydrocarbons. Such solutions may be introduced to the system by way of a line 29 containing a control valve 30 4and pumped by a pump 3| through a line 43 containing control valve 44 intotreater 28, the solutions ilowing in a large number of small streams through the interstices in the filling material which may be for example, silica fragments, crushed rebrick, etc.v As shown in the drawing',

Vthe solution is owing in the same direction as the vapors though if necessary a countercurrent operation may be employed. Heavy hydrocarbon liquids and solutions ofpartly spent condensing agents may be withdrawn from treater 23 through line 3'2 containing control valve 33 to a receiver 34 in which separation of gases, hydrocarbon liquids and aqueous solutions may be eiected. .Line

4I containing control valve 42 permits the venting oi' any gas accumulations, line 39 containing control valve 40 may be used to withdraw a hyd rocarbon layer which is then` returned Vto Nthe treating system if desirable or convenient and line containing control valve 38 permits `the rejection of Aspentcatalytic solution., The solution may be recirculated by way of line 35 containing control valve 36 which leads to ieedY pump 3|. The recirculating idea may be further utilized minum and other anhydrous metal chloridesof ysimilar charactenthese chlorides having a tend-` ency'toform organic complexes in which a halide residue is associated with an aromaticor alkylated aromatic radical. Compounds of this character are viscous liquids which frequently possess greater catalytic action than the original metal halideand which maybe recirculated for a long time without change in constitution or loss of catalyticproperties. Thus the layout. shown n connectionwith treater 28 may be used to recir- .culate such catalytic liquids.

Owing tothe general applicability ofthe proc- Y.ess for increasing the yield and quality of gasolines produced bycracking `various charging oils,

a large number of examples ,of -results obtainable by its use might be given, `It will lbe suilicient, however, to given one involving the cracking and treating of aV crude oil i'rornthe Mount Pleasant district of Michigan, the vgasoline produced by straight run distillation of this crude being distinctly inferior in anti-knock rating. Correof satisfactory quality.

4 `:The characteristicsA or. the crude oil serving as -chargingstock to a plant similar in .general layout tothe one'described in connection with the 'drawing had the following characteristics;

Gravity A. P. I 42.7 I. n.1?. F. 113

%.at43rr'. k4o wat 572 F. f- 59.5

`The gasoline, including the Ymaterial boiling up to 437 F., had a low knock rating of the order oi' l0 to 20 octane number. l,

When cracking this crude ina plant of commercial design Vat a pressure of 350 pounds per square inch and a maximum temperature of 950 F., (measured at the exit of the heating coil), there may be produced a total of '72.5% by volume ot 61.5 gravity 400 end point gasoline having an octane number of 53, which is still considerably below the value demanded by specifications tor premium gasoline which is in the neighborhood of 70 octane number.

Incidental to this cracking operation there may be produced for each barrel of charging oil 350 cubic -feet of a gas mixture having the following composition:

- The specmc gravity of uns gas mixture (which includes all the light hydrocarbons not con- `spondingly, the heavier .and .less valuable frac- `tions of this crude are'difllcult to crack iorthe production. of gasoline in satisfactory yield and densed with the gasoline fractions from the Lcracking plant) mayrbe 1.249 referred to air as unity. l v y ,p

It will bev observed that inthe xed gases thus produced Vthat oleflns of 3, '4 and 5 carbon atoms Y constitute 52.5% by weight of the'total gas mixture, which correspondsto 6'7 by weight of the l the distillate' m form aikyiated charging oil. r When `operating according to the process of the present invention in contrast .to the ordinary cracking operation just described, commercial benzol may be injectedinto the vaporsfrom the fractionator of the cracking plant in an amount roughly corresponding to that necessary for the formation of mono alkyl derivatives from the oleilns of 3, 4 and 5 carbon atoms;I this amount being roughly 10% by weight of the charging oil. The benzol thus injected may be warmed so-that the temperature of the mixture lentex'ingrthe catalytic treater-i'sapproximately 350 F. under pressure of about 50 pounds per square inch. The

catalytic material employed may be an inert siliclous carrier impregnated with y25% of commercial zinc chloride. n

As a result of this operation theremay be proapproximately duced from'the crude oil chargingstock an amount of gasoline equal to 86% by Avolum'eQthis gasoline having the following characteristics:

Gravity wir'. I 55 x Iniuiu boiling point-; 100 F. 50%,over at 275 F. Final boiling point cio" r'.

Octane number i D5 The benefits gained by the operation described` are readily apparent, to those familiar with reflning petroleum and the value Vofga'soline as judged fromits test data. Not onlyis the yield substantially improved by conserving the reactive oleflns but the anti-knock'value expressed as octane number has been raised tov af point far in g excess of the demands of premium gasolines.

' shown its commercial value but the invention is not confined to the exact details used in the descriptive portion nor the figures shown in the example.. n

I claim as n'yinventlon:

l. A process for increasing the gasoline yield' Y and quality of cracked d istillatecontaining vgasoline and low boiling oleiins, which comprises adding to the Adistillate an aromatic hydrocarbon vboiling within they gasolineV range, and reacting such added aromatic with oleflns contained in derivatives boiling within the motor fuel range. l y

2. In the cracking of hydrocarbon oils wherein there is produced an overhead distillate contain- `ing gasoline andk gaseous olefins, the method of increasing -the yield and quality of the gasoline produced by the cracking process, which comprises adding to the distillate an aromatic hydrocarbon boiling within the gasoline range, and reacting Athe added aromatic with gaseous olefins contained in the, distillate to form alkylated derivatives boiling within the motor fuel range.

3.'In the cracking ohydrocarbon Aoils wherein there is produced'a vaporous mixture of gasoline.

and normally gaseous oleflns, the method of increasing the-yield and quality of-v the gasoline produced bythe. cracking process,'which comprises adding to said vaporous mixture an aromatic hydrocarbon boiling within the gasoline range, reacting the aromaticwith at least a portion` of vsaid normally gaseous oleflns to form alkylated derivatives boiling within the 'motor fuel range, condensing the gasoline boiling vapors containing the alkylated derivatives thus formed,

`and separating the resultant condensate from the remaining incondensible gases produced by the cracking.

4. In the production hydrocarbon oil' is cracked, the resultant mixture of 4vapors and gases fractionated to'condense and separate hydrocarbons heavier than gasoline, thefractionated mixture subsequently subjected to nal condensation to condense the gasoline and the4 latter separated.` from incondensble gases; vthe improvement which comprises adding to the mixture of vapors and gases, intermediate said fractionation and final condensation, an aromatic hydrocarbon boiling within the gasolinerange, reacting the added aromatic with olefins contained in the fractionated mixture as a result of the cracking to form alkylated derivatives boiling within the motor fuel range, and recovering the alkyiated derivatives thus formed in the gasoline condensate formed by the ilnal condensaion. 1

GUSTAV EGLOFF.

)of motor fuel .wherein

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