US2275377A - Process of manufacturing motor fuel - Google Patents

Description

' March 3, 1942. F. E. FREY PROCE-SS OF MANUFACTURING' MOTOR FUEL Filed April 2, 1940 INVENTOR AT roRNEYs FREDERICK E. FRI-IY BY KMWM www@ Patented hier. 3, i2

IPRGESS @IF M Y ASTURN G MOTOR Frederica a. rm, amneville, oma., assigner 'to :mi: Petroienm Company, a corporation of Haelen/are Application April 2,

la Ciaincs.

The invention relates to a process of manufacturing motor fuel, and more particularly to the manufacture of motor fuel of increased antiknock rating and decreased volatility from aliphatic hydrocarbons having three to ten'carbon atoms to the molecule.

The invention comprises, in combination, the following steps: alkylating isoparafns of relatively low molecular weight, such as isobutane, isopentane, and isohexanes, with olens to yield chiey isoparains. that have a relatively low volatility and that boil in the motor-fuel range; subjecting the resultant motor-fuel hydrocarbons and the accompanying hydrocarbons of relatively lower molecular weight to dehydrogenating conditions, which cause a conversion of part of the motor-fuel hydrocarbons to hydrocarbons of substantially the same boiling range but of substantially greater anti-knock rating and a conversion of part of the parains of relatively lower molecular weight to the corresponding olens; separating from the resultant mixture the hydrocarbons boiling in the motor-fuel range; and returning at least a part of the residual hydrocarbons of relatively lower molecular weight to the alkylation step.

An object of, this invention is'to provide a process of manufacturing motor fuel.

Another object is to utilize aliphatic hydrocarbons having from three to five carbon atoms per molecule for the manufacture of motor fuel,

Another object is to reduce the volatility of the lower isoparaiiins, having from four to six carbon atoms to the molecule, and thus to improve them for incorporation in motor fuel.

Another object is to increase the anti-knock rating* of motor, fuel produced by the alkylation of isoparains with olens.

Another object is to effect, in one conversion step` an increase in the anti-knock rating of motor fuel produced by the alkylation of iso- I paraiins with olefins and a dehydrogenation oi' parafns of low molecular weight to olefins suitable for the production oi additional amounts of motor fuel by alkylation.

Other objects and advantages of this invention will be obvious to those skilled in the art from the following disclosure and discussion.

The invention will be readily understood from the following description and the accompanying drawing, which shows a now-diagram for a preferred mode of operation.

1940, Serial No. 327,529

The feed, comprising isoparafns of relatively low molecular weight, such as isobutane, isopentane, and isohexanes, enters the system through inlet l having control-valve 2. The isoparainsware subjected to alkylation in the alkylator 3; the'olens required for the alkylation 'are introduced into the alkylator either with the feed or otherwise as by one or more auxiliary inlets (not shown) that facilitate maintaining an olen concentration that is low-compared to the concentration of isoparans in the alkylat'or. By the alkylation originally charged isoparaflins are converted into heavier isoparains that boil principally in the motor-fuel range, such as isoheptanes, isooctanes, isononanes, isodecanes, and the like.

From the alkylator the eiliuent, containing newly formed isoparaiiins and unreacted hydrocarbons, passes through conduit 4 and valve 5A to the heater 6, where thel hydrocarbons are heated to a temperature within the dehydrogenating range, generally between 750 and 1250 F. Thence the hydrocarbons are maintained under dehydrogenatin'g conditions in the dehydrogenator 'l until a desired degree of dehydrogenation has been eiected, advantageously in the presence -of a dehydrogenating catalyst such as catalysts comprising alumina, bauxite, especially hard Arkansas bauxite, chromium oxide, especially black unglowed chromium oxide, or the like. The temperature preferably is between 750 and 1100C F. when the dehydrogenation catalyst comprises black unglowed chromium oxide, and between 1000 andrv0 F. when the catalyst consists of alumina or bauxite, or the like.

Alternatively, valve' being closed, the hydrocarbons from the alkylator 3 may be passed r through conduit t vand valve 9 into the fractionator i0, wherein a fractionation into a light and a heavy fraction is made. The light frac- .tion which contains the major part of the hydrocarbons boiling in the motor-fuel range and all of the lighter hydrocarbons, passes through conduit il and valve i2 to the heater t and dehydrogenator l, where, as has been explained,.a desired degree of dehydrogenation is eiected. The heavy fraction from the fractionator i0 maybe withdrawn, under certain conditions of fractionation, as an oil through valve i3 and outlet i6; or, alternatively, under such condi tions of fractionation that it contains a con` siderable but minor part of the hydrocarbons boiling in the motor-fuel range, it may be passed through valve l5 and conduit i6 to the separatn ing means il; or, still alternatively, if the con ditions of operation are such that the heavy fraction from fractionator i0 consists predomi nantly of heavy unsaturated hydrocarbons such as polymers oi the gaseous olens that boil above the motor-fuel range, part or all of it may be passed through valve I8 into the recycle stream I9, Vwhich carries the heavy unsaturated hydrocarbons to the alkylator 3, where they may be usedto alkylate isoparaiins. Such heavy unsaturated hydrocarbons, especially heavy polymers and/or co-polymers of propylene and the several butylenes, appear to be practically as suitable for the alkylation of isoparafiins as the light-gas fraction containing hydrogen and the major part of any hydrocarbons having less than three carbon atoms to the molecule, a heavy-gas fraction containing mainly hydrocarbons bjling' may be withdrawn through valve and outlet 25;

or alternatively, part` or all of the heavy-oil fraction may be passed, especially if it consists predominantly of` heavy polymers of propylene and/or the several butylenes, through valve 21 into the recycle stream i9, which carries the heavy polymers to the alkylator A3.

The heavy-gas fraction from separator i1 may be passed through conduit 28 and valve 29 into the recycle stream I9, which carries the heavy gases to the alkylator 3. Alternatively, valve 29 being closed, the heavy-gas fraction from separating means l1 may be passed through valve 39 and conduit 3i to the heater 32, wherein the heavy-gas hydrocarbons are heated to a temperature within the dehydrogenating range, generally between '750 and 1250 F., and thence into the dehydrogenator 33, wherein the hydrocarbons are maintained under dehydrogenating conditions similar to those already` described for de hydrogenator 1 until the content of olefin hydrocarbons has been increased to a desired value; or, still alternatively, valves 29 and 30'being closed, the heavy-gas fraction from separating means t1 may' be passed through valve 34 and conduit 35 into the separator 36, wherein the parailns are separated from the oleflns, as by solvent extraction, azeotropic distillation in the presence oi' a polar oxygen-containing compound such as suli ur dioxide, ethylene oxide and methyl formate.v

and the like, as described in the Patent 2,186,524, of Frey et al. The parains pass from the separator 36 through valve 31 and conduits 38 and 3i to the heater 32 and dehydrogenator 33, where they undergo dehydrogenation to a desired extc'nt. through valve 39 and conduit 40 into the recycle stream i9, which carriesV them to the alkylator 3.

From the dehydrogenator, 33, theproducts'of dehydrogenaton and the unreacted paraiiins may be passed through valve 4| and conduit 42 into -recycle stream I9, which carries them to the alkylator 3: or, alternatively and preferably, valve The oleilns pass from' the separator 3%5Y v 4l being closed, the dehydrogenation products and the unreacted parafiins may be passed through valve 43 and conduit 44 into separating means 45, wherein separation into a light-gas Vfraction and a heavy-gas fraction is effected. The light-gas fraction, consisting mainly of hydrogen and the major part of any hydrocarbons having less than three carbon atoms per molecule, is withdrawn through valve 46 and outlet 41. The heavy-gas fraction, consisting mainly of olefins and paraiiins having at least three 'carbon atoms per molecule, passes through valve 48 into the recycle stream I9, which carries it to the al'- kylator 3; however, if desired, part or all of the heavy-gas fraction may be passed through valve 49 and conduit 50 into'separator 33, wherein seperation into oleflns, which pass through valve 39 and conduits and I9 to the alkylator 3, and into paraflins, which pass through valve 31 and conduit 38 to the heater 32 and thence into dehydrogenator 33, is effected. The best mode of procedure for any given feed stock may be readily determined by trial. Oleflns suitable for reaction in alkylator 3 may, if desired, be introduced through conduit 5I and valve 52 toponduit i9, either as the sole olen charge to the alkylator 3 or to supplement olens formed in the process.

It will be readily appreciated that the diagram serves only as a flow sheet which shows the essential functional elements which contribute to the combination of the process. In actual operation there are included numerous pumps, compressors. cooling' and heating units, etc., all of which are incidental to lthe major units shown and can be readily supplied and adapted in known modincations by one skilled in the art. Separating means i1 and 45 generally comprise various com- Dressors. fractionators and the like, and separator 3S generally operates with the agency of a selective solvent, many of which are known to the art and all of which require various pieces of equipment not shown.

Feed stocks suitable for the process may include mixtures of paraffin hydrocarbons of from three to ten carbon atoms per molecule, provided that a substantial proportion of isoparaiiins is present. Suitable mixtures are natural gasoline, casinghead gasoline, crude oil distillates, and other similar mixtures comprising isoparains having from four to six carbon atoms per molecule. These isoparailins, namely, isobutane, lsopentane, and isohexanes, are the chief components of such mixtures for which a reduction of volatility by alkylationl is desirable. The normal parafns present in such mixtures also may undergo alkylation, although generally only to a relatively minor extent, depending upon conditions present during the alkylation step. Of the paraffins that do not undergo alkylatlon, part of the relatively heavy ones, especially of the heavy normal paraflins, pass through the process unchanged and are incorporated as such in the motor-fuel product; part of the relatively heavy ones are converted in the dehydrogenation step into olens. aromatics, and cycloolens that boil in the motor-fuel range and that are incorporated in the motor-fuel product; part of the relatively light ones "undergo conversion in the same and/or a subsequent dehydrogenation step into olefins that serve as reactants for the alkylation of isoparains; and a relatively minor part 0 1' the relatively light ones break up into very light hydrocarbons that advantageously are vented from the system with the hydrogen obtained as a bycatalysts, as for example the process disclosed in the copending application of Frey et al., Serial- No. 87,790 (Patent No. 2,233,363. However, either concentrated sulfuric acid or concentrated hydrouoric acid is preferred as alkylation cata-l lysts, as they have an advantageous ability to. cause fragmentation of heavy. polymers or other heavy unsaturated hydrocarbons into fragments, which unite with isoparaillns to give alkylationv products which have higher molecular weights arrasar??` l Fractionation. removal of light gas, removal of heavy oil, separation of oleflns from paraillns, re-

cycling of heavy polymersvto the alkylator, and the like steps may be practiced in accordance with the more general description already given.

As is illustrated bythe foregoing example, the

invention e'ects the manufacture of motor fuel ofv increased anti-knock rating' and decreased volatility from aliphatic hydrocarbons having three to ten carbon atoms to the molecule. Aliphatic hydrocarbons having three to ve carbon atoms to the molecule are utilized, and the volatility of isoparailins having four to six carbon than the original isoparaiiins, but which do not equal the molecular weights of the original isoparaiiins and heavy oleilns.

The following example is given to illustrate one of the many possible modesof operation: it is not necessarily to be taken as establishing limitations of the invention.

Example This example illustrates a mode of operation suitable for the manufacture of a motor fuel from a petroleum cut. containing parailins of three to ten carbon atoms per molecule, of which 85 per cent of the material having five or more carbon atoms per molecule distills up to 212'F. Such a petroleum cut maybe subjected to alkylation with olei'lns, preferably of three to-ve carbon atoms per molecule, as in the presence of sulfuric acid having a strength of more than about 90 per cent, advantageously from 96 to 102 per cent. To minimize concurrent polymerization reactions. the mixture of hydrocarbons and sulfuric acid must be vigorously agitated, and the concentration of, olens must be kept low relative to the concentration ofisoparaillns. The reaction teml perature` must be kept between 0 and 125 F., preferably at about 50 to 85 F. Aftera suitable extent of alkylation has been obtained, the hy-l drocarbons are freed from the acid. The hydrocarbons then are virtually olefin-free and have an increased amount of material having ve or more carbon atoms to the molecule: of this material, only 60 to 65 per cent boils up to 212 F. After being freed from the alkylation catalyst, the hydrocarbons may lbe passed through a catalytic dehydrogen'ator containing bauxite, advantageously granular hard Arkansas bauxite 'washed atoms to the molecule is'reduced. `An increase in theanti-knock rating of motor fuel produced by alkylation of isoparafllns withy oleiins and a dehydrogenation of paraiiins of relatively low molecular weight into olens are effected in one conversion step.

As many modifications of the invention will be obvious to those skilled in thev art, the invention should not be limited unduly by the foregoing specification and example, but it should be understood to be extensive in scope and equivalents,

within the scope of the lappended claims.

I claim:

l. An'improvedprocess for the production'of a motor fuel having a low volatility and a high octane number. which comprises reacting by al-4r kylation paraiiln hydrocarbons of from. three to six carbon atoms per molecule with olefin hydrocarbons to form paraflln hydrocarbons of a higher number of carbon atoms per molecule than said initial paraillns and in the motor fuel boiling range, passing atleast a part of the eilluent of said first step comprising hydrocarbons in and below' the motor fuel boiling range to the action of a dehydrogenation catalyst at a dehydrogenation temperature to improve the octane number of motor fuel hydrocarbons and concomitantly vto produce plefins lower boiling than motor. fuel, separating fromthe dehydrogenation free from dust particles in accordance with the copending application `of Blaker and Matuszak,

Serial No. 328,594, ied April 8, 1940, at a tem- Y perature of about 1000" F. or higher. The dehydrogenation and other reactions promoted by of the material having live or more carbonatoms to the molecule from an initial value of about 7D to a value of about '74. vAccompanying this change in octane number there is an increase in the degree of unsaturation, but there is relatively The genation in a second catalytic dehydrogenator.' a

the bauxite effect a change in the octane number eilluent a fraction comprising hydrocarbons in the motor fuel rangeand removing said fraction from the process, separating also a fraction containing oleflns lower boiling than motor fuel and passing said fraction to said alkylation step.

2. A process of manufacturing motor fuel, which comprises alkylating isoparamns of four to six carbon atoms to the molecule with oleiins in the presence of concentrated sulfuric acid, subjecting the resultant motor-fuel hydrocarbons and the accompanying hydrocarbons of relatively lower molecular weight to the action of a dehydrogenation catalyst at a dehydrogenation temperature, separating fromvthe resultant mixture'of the hydrocarbons boiling in the motor-fuel range, and returning at least a part of the residual hydrocarbons to the alkylation'step.

3. A4 process of manufacturing motor-fuel of increased anti-knock rating and decreased volatility from aliphatic hydrocarbons of from three to Vten carbon atoms to the' molecule and containing isoparailins of four to six carbon atoms .to the molecule, which comprises subjecting the said hydrocarbons, together with recycled olefins, to the action of sulfuric acid having a 'and below the motor fuel boiling range to the action of -a solid dehydrogenation-catalyst at a temperature between 750 and 1250 F. for a periresidual hydrocarbons having from three to ve carbon atoms to the molecule and containing said oleiins to the alkylation step.

4. The process of claim 3 wherein the dehydrogenation catalyst comprises bauxite and the temperature is within the range. of 1000fto 1250 F.

5. The process of claim 3 wherein the dehydrogenation catalyst comprises black unglowed chromium oxide and the temperature is within the range of 750 to l100 F. g

6. A process of manufacturing motor fuel of increased anti-knock rating and decreased volatility from aliphatic hyrocarbons of from three to ten carbon atoms to the molecule and containing isoparains of four to Sixcarbon atoms A. to the molecule, which comprises subjecting the said hydrocarbons, together with recycled olefins, to the action of sulfuric acid having a strength of 90 to 102 per cent by weight, at a temperature between about and 125? F. until a desired extent of alkylation is obtained; subjecting at least a part of the eilluent of the alkylation operation comprising hydrocarbons in and below the motor fuel boiling range to the action of a solid dehydrogenation catalyst at a tempervature between 750 and 1250 F. for a period of time to obtain a substantial extentl of dehydrogenation. separating from the resultant mixture the hydrocarbons boiling in the motor-fuel range; subjecting at least a part of the residual hydrocarbons having three to five carbon atoms to the molecule to a second dehydrogenation step; and returning olefin hydrocarbons having three to five carbon atoms to the molecule from the second dehydrogenation step to the alkylation step as the recycle olens. I

7. A process of manufacturing motor fuel of boiling in the motorfuel range; and returning at least a part of the distillate react with said olefin hydrocarbons to increased anti-knock rating and decreased volatility fromaliphatic hydrocarbons of from three to ten carbon atoms to the molecule and containing isoparaiilns of four to six carbon atoms to the molecule, which comprises' subjecting the said hydrocarbons, together withl recycled oleilns, to the action of sulfuric acid having a strength of 90 to A102 per cent by weight, at a temperature between about 0 and 125 F. until a desired extent `of alkylation is obtained; subjecting at least a part of the effluent of the alkylation operation comprising hydrocarbons in and belw the 'motor fuel boiling range to the action of a solid dehydrogenation catalyst at a temperature between 'l50and 1250" F. for a period of time to obtain a substantial extent of dehydrogenation, separating from the resultant mixture'the` hydrocarbons boiling in the motor-fuel range: separating the Vresidual hydrocarbons having three to five carbon atoms tothe molecule into an olefin part and a parailin part; returning the olefin part to thel alkylation step as the recycle olenns; subjecting the paraiiin part to a second dehydrogenation step; and returning the hydrocarbons having three to five carbon atoms to the molecule from the second dehydrogenation step to the alkylation step, 1-

8. A process of manufacturing motor fuel of Vincreased anti-knock rating.` and decreased volatility from aliphatic hydrocarbons of from three to ten carbon atoms to the molecule and containing isoparaflins of four to six carbon atoms to the molecule, which comprises subjecting the said.

hydrocarbons, together with recycled olens, to the action of sulfuricacid having a strength of 90 to 102 per cent by weight, at a temperature between about 0 and 125 F. until a desired extent of alkylation is obtained; passing the effluent to separating means,v separating therefrom unsaturated hydrocarbons produced in side reactions by the action of said sulfuric acid and boiling above the motor-fuel range and returning same to the alkylation step; separating also a hydrocarbon fraction comprising motor-fuel hydrocarbons and hydrocarbons boiling below the motor-fuel range and subjecting same to the action of a dehydrogenation catalyst at a'temperature in the range 750 to 1250 F. until a substantial extent of dehydrogenation is obtained; separating from the resultant mixture the hydrocarbons boiling in the motor-fuel range; and separating also from the resultant mixture at least a part of the residual hydrocarbons having from three to five carbon atoms to the moleculeand returning same. to the .alkylation step, said unsaturated hydrocarbons and said residual hydrocarbons comprising said recycle olefins.

9. The process of claim 8in which the dehydrogenation catalyst comprises black unglowed chromium oxide and the dehydrogenation temperature isin the range of 750 to 1100' F.

10. The process of claim 8 in which the dehydrogenation catalyst consists of bauxite and the dehydrogenation temperature is in the range of 1000 to 1250* F.

lL'A process of manufacturing'a motor fuel of increased anti-knock rating and decreased volatility from light petroleum distillates containing substantial amounts of isoparailins of from f-our to six carbon atoms per molecule, which comprises subjecting such a distillate together with oleflns to an alkylation reaction in which some of the parailin hydrocarbons in said produce paraffin hydrocarbons of highermolecular weight, passing at least a part of the effluent' -of said alkylation reaction comprising hydrocarbons boiling in and below the motor fuel range `to the, action of a dehydrogenation catalyst at a dehydrogenation temperature to improvethe octane number of said hydrocarbons boiling in the motor fuel range and concomitantlytoproduce oleflns lower boiling than-motor fu`el, separating from the dehydrogenation eilluent a fraction comprising hydrocarbons boiling in the motor Y fuel range and removing said fraction from the process. separating also a fraction containing oleflns lower boiling than motor fuel and passing i said fraction to the 'alkylation operation.

1 l2. 'A process of manufacturing a motor fuel of increased anti-knock rating anddecreased volatility from natural gasoline containing substantial amounts of isoparamns of from four to six carbon atoms per molecule, which comprises subiecting said natural gasoline together with olens `to an'alkylation reaction in which some of the hydrocarbons in said natural vgasoline react with said olenn hydrocarbons to produce paranin hydrocarbons of higher molecular weight, passing at least a part ofthe emuent of said alkylatlon reaction comprising hydrocarbons boiling in and below the motorl fuely range to the action of a dehydrogenation catalyst at a dehydrogenation temperature to improve the octane number of said hydrocarbons boiling in the motor fuel range and concomitantly to produce oleflns lower boiling than motor fuel, separating from the dehydrogenaton eiiluent a fraction 2,275,377 comprising hydrocarbons boiling in the motorfuel range and removing said fraction from the process, separating also a fraction containing olens lower boiling than motor fuel and passing said fraction to the alkylation operation.

13. A process of manufacturing motor fuel, which comprises alkylating isoparaillns of four to six carbon atoms to the molecule with olefins 14. A process of manufacturing motor fuel of.

increased antiknock rating and decreased volatility from low boiling aliphatic hydrocarbons, which comprises subjecting paraln hydrocarbons of from three to ten carbon atoms per molecule together with recycled low boiling olens to an alkylation reaction in which some of the paramn hydrocarbons react with said olefin hydrocarbons to produce parailln hydrocarbons of higher molecular` Weight and in the motor fuel boiling range. subjecting at least a part of the eilluent of said alkylation-operation comprising hydrocarbons boiling in and below the motor fuel range to a catalytic treatment at an elevated temperature such as to improve the antiknock rating of said hydrocarbons boiling in the motor fuel range, separatinsfrom the resultant mixture hydrocarbons boiling in the motor fuel range, subjecting at least a part of the residual hydrocarbons having three to five carbon atoms per molecule to a second catalytic treatment at an elevated temperature such as to dehydrogenate parafilns and produce low yboiling oleflns, and returning olefin hydrocarbons having three to ve carbon atoms toithe molecule so produced to the alkylation step as said recycled oleiins.

- FREDERICK E. FREY.

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