US2740820A - Olefin isomerization process - Google Patents

Description

April 3, 1956 H. L.. wlLsoN ET Al. 2,740,820

OLEFIN ISOMERIZATION PROCESS Filed Feb. 29, 1952 .Qober @regia y 2,740,820 oLEFlN IsoMERIzATIoN PROCESS Howard L. Wilson, Raritan Township, Middlesex County, and Robert Drogin, Linden, N.. I., assignors to Esso Research and Engineering Company, a corporation ofY g i Delaware Y Y Application February 29, 1952, serial No. 274,248';

1s anims.` (c1. 26o-683.2)

CH2=CHR wherein Risen alkyl group, are produced bycrack` ing hydrocarbons and by various synthetic procedures.

It is frequently desired to produce internally unsaturated oleiins for use in high octane fuels, for making various flo 2,740,820 Patented Apr. 3, 1956 ICC 2 persing aid such as a high molecular Weight fatty acid, carbon black, or the like.

The olefin feed and alkali metal are thoroughly agitated by thestirrer to form a concentrated dispersion or emulsion of thealkali metal in the feed. Conveniently the drums may be steam jacketed or heated-by means not shown in order to prepare the dispersion at a temperature of about 100 to 130 C. or higher. In this manner thealkali metal will be dispersed as minute molten drop-v lets suspended or emulsied in the hydrocarbon; with the use of a'dispersing aid,v an extremely stable suspensionis prepared. This concentrate may contain as high as l to 50% of alkali metal, and will generally be suciently uid for subsequent handling.

After dispersion has beenprepared in one drum, it is passed through line 14 containing pump 28 by controlling valves 29 or 30. A similar dispersion may then be made in the other drum for subsequent use. The dispersion passing through line 14 is combined with olen feed passing through line 13 in a proportion such that an alkali metal concentration of about 0.01 .to 5.0 Weight l' per cent, based on the oleiins, is obtained. The mixture chemical intermediates, for producing specialtypes of olefin polymers andthe like. `The chief object ofthe present .invention is to disclose an effect-ive meanstor accomplishing olefin isomerization whereby double bond shifting and possibly other rearrangement of the molecule takes place. i Y

In accordance with the present inventiomhigh molecularV weight Aalpha oleiins are intimately contacted with alkali metal at an elevated temperature. After the desired degree of isom'erizationhas taken place, alkali metal and undesirable` reaction `products are separated from the reaction mixture, and a product including internally unsaturated mono-olens is recovered. y, The discovery that alkalil metals have the ability to catalyze the isomerization of high molecular weight olens is completely unexpected since olefinl isomerization"usuf ally involves, `acid conditions. The result is also unertpected since the alkali metal is `speciiicfor isomerizing olens having at lleast 10 or more carbon atoms, olelins havingasmallernumber of carbon atoms Vbeing substan-l tially unaffected.

The present invention will be` better understoodfh'y f t' erence to the sole figure of the drawing, taken inconnection, `with `the .following description of a,l continuous method for carrying out olefin isom'erization.V Referring to the gure, an olen feed prepared by means not shown is introduced into the system by meansV of line 11. feed may for example have a boilingrange of about 200 tofffSOfV C. and will include substantialrquantities ofV The' "u" alphaolens having from about ll to` 20 carbonatoms.

A portion of therfeed is charged by4 pumpv172-through l'ine13 and line 14 -to preheatery 15. Another portion ofrthe feed is passed to one of dispersion'makeupl drums- 16t0rj17- through lines 18 or 19 controlled, respectively, by valves 20 and 21. Each of the drums includes' an agitating means, such as propellers `22`ixed to a shaft rol.' tated'by prime A"mover means not shown, whereby ahigll degree of shear is obtained; l Alkali metal is introduced into drums'16 or 17 through line 23 and branch lines 24 and Z'S'includiug,v respectively,

valves 26 and 27. 'If-hey alkali metal isconvenientlyintroduced as an alkali metal sand which is a coarse granulatedisuspension of th'emetalin aninert liquid medium, the Imetal having particle sizesfas low as 2` orlower.l The metal suspension may also include adisj rounded by jacket 33 having an inlet 34 and outlet 35' through which a heating medium such as V steam or the like may be passed to maintain reaction temperature.

The reaction zone includes an impeller 36 rotated through shaft 37 by a prime mover such as a motor 38.' Impeller 36 is positioned at the lower end ofdraft tbe 39., the draft tube being centrally disposed in reaction zonejhousingZ.

. `Reactants and catalyst introduced into zone 32 are forced byimpeller 36 upwardly through'draft tube 39 and are circulated downwardly through annular space 40 between the Walls of the` reactor and draft tube. A high degree of agitation is thus obtained, and the olens are thoroughly contacted with the dispersed metal in order to obtain maximumrutilization of the latter.

.Reaction zone efuent is withdrawn at a constant rate through line 41 positioned in the .top of zone 32 vand is forced through pump 42into the'lower portion ofsoaker 43. .The soaker likewise includes a draft tube 44 and an impeller 45 arranged to give good circulation and agitationduring the soaking period. Thesoaker does not-requireheating. The contents of the soaker are maintained near the reaction temperature by the specific heat-available. This gives additional residence time at somewhat below the reactor temperature but suiciently high to complete the isomerization reaction.

Y Etliuent is'passed from zone 43 by line 46 through a heat exchanger or chiller 47 wherein it may be further cooled. The cooled efiluent is then passed through line 48 containing pump 49 into one of a plurality of filter Lbeds 50V or 51 by means of` branch lines 52 or ,53 conl taining valves 54 and 55, respectively. The lter beds may be provided with a suitable ltering material,` such v as diatomaceous earth or the like, one filter bed being used while the other -is being regenerated or relled with fresh clay. Alkali metal, sludge and any other undesirable reaction products or unreacted solids are removed from the treated hydrocarbon during the filtering step.

The product containing isomerized olens is withdrawn through line 56.`

In order to improve the utiliatizon of alkali metal and I to speed the isomer-ization reaction, it is preferred to add anv activator such as aliphatic alcohol cr the like vto the reactants. l This may be done by charging, for example,

isopropyl alcohol through line 9 containing pump 10 into line k1,3, wherein the alcohol is combined with the ole workman that the subsequent treating of the isomerized product willV depend upon its ultimate use.

The temperature at which the isomerization reaction is carried out will generally be above about 15.0 C. and should be below the incipient cracking temperature of the hydrocarbons (about 425 C. or higher), a preferred range being about 175 to 350 C. It is-preferred to carry out the operation under pressures suiciently lhigh` to keepl the hydrocarbonsv in the liquid phase.- Reaction times are generally not criticaland will depend to a large extent on the temperature as Well as the size of the dis-vv persed alkali metal particles.

The rate at'which thek reaction proceeds will be controlled'to a large extent by the metal surface available.

Obviously, dispersed particles having average diameters-as low as about 0.001 to 10'microns will have'manytimes. the surface area of the same concentration of particles having diameters as high as 100 to 1,000 microns. l For these reasons, it is preferred that the alkali metal be in finely divided form during the contacting step. Finely dispersed `particles having sizes below about 50 to l1000- microns in average diameter are generally more'useful than larger. sized particles.

.The particle4 size will also influence the concentration of alkali metal needed to effect a desired conversion. Under some conditions, as low as 0.01 to 011 weight' percent alkali metal, based on the olefin in the feed, will be` sufficient providingV finely sized dispersed particles are used. On the other hand, up to l or 20 weight percent alkali metal may be desired when using larger particles. A generally useful range is about 0.25 to 5.0 weight percent of the alkali metal based on the oleiins. Under these conditions, contact times may vary from below about 5' minutes up to 5 or 10 hours, although about 30 minutes'to 3 hours will generally be suicient.

The alkali metal employed in the practice of the present invention is preferably sodium although potassium, lithium, mixtures of alkali metals, or certain active alloys containing alkali metals are useful. As pointed out above, the isomerization reaction is greatly facilitated by using alkali metal in thev dispersed form, the particles preferably being molten although solid particles may be used successfully.y Suitable dispersions may be obtained by utilizingr high speed-agitator; colloid mills, hoinogenizers and the like fory the thoroughly dispersiug molten metal in a suitable vehicle.

In order to maintain the metal catalyst in the dispersed state, it is desired to employ a dispersingagent. Organic compounds which are soluble in the hydrocarbon medium are. preferred. Such materials include the higher molecuf larv weight fatty acids or their soluble metal soaps. Gar.- bon black may also be used for this purpose. Generally an amount of dispersing aid in the range of 0.5 to. 510 weight percent, based on the alkali metal will be adequate.

Itis also preferred to have an organic activator present during the isomerization step. These materials' help to keep the surface ofthe alkali metal clean and'may in some other` way-activate and accelerate the reaction. in' the rangev of about l to 30 mol percent, preferably 5j to l5 m01Y percent, of activator, based on the alkali metal, will generally be sufficient, although smaller or larger amounts may be useful in some cases. The most suitable activators are organic compounds consisting of carbon, vhydrogen and oxygen, and termed herein oxy hydrocarbons, having below about carbon atoms. Particularly preferred are such compounds containing an active` hydrogen suchfas fatty acids, alcohols, polyhydroxy alcohols such as gly` cols, alcohol-ethers, phenols, malonic esters, etc. Other compounds such as ketones, ethers and the like may be used.- alcohols, such as ethyl, prQpyL butyl. and particu.: larly the secondary and tertiary alcohols such as isopropyl, secondary and tertiary butyl alcohols, etc., are useful. Other specific activators include ethylene glycol, propylene glycol, 1,2-butanediol, erythritol, diethylene glycol, phenol, cresol, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl ether, isobutyl ether, etc.

The feed stocks used in the practice of the present invention may be substantially pure individual or mixed alphaolefns having at least about 10 carbon atoms. It is generally preferred that the olelins contain below about 25 carbon atoms. Specific mono-olefins include decene-l, dodecene-l, octadecene-L eicosene-l, tetracosenefl, and other straight or branched chain alpha-olens which are amenable to isomerization in accordance with the present invention. l

The olefin feed stocks may also be obtained from thermal orcatalytic'crackingof hydrocarbons such as gas oils, parainic waxes, petrolatums andthe like or'by polymerization'of low molecular Weight olens. A convenient source of feed stock is the so-called Fischer synth'csis.A process in which carbon monoxide is hydrogenated in the presence of metal oxides or other catalysts. For example, relatively high concentrations of alpha-olefins are sometimes found in Fischer synthesis products produced when using iron oxide catalysts. Products from these various operations may be distilled, solvent extracted, extractively distilled, and the like by conventional procedures to obtain feed stocks containing useful concentratonsf'of the desired alpha-olens.

The feed stocks may comprise in addition to alphaolensrelatively high concentrationsof paratiins, naphthenes;y aromatics and other hydrocarbons boiling in the same or'diterent'boilingrange It is preferred ofcourse that these extraneous hydrocarbons be substantially inert to reaction with or polymerization by the metal catalyst. For example, the feed stock should be substantially free or'contain only very small concentrations of acetylenic or dioleiinic' hydrocarbons, sulfur and nitrogen compounds, water and the like. Such compounds may under the conditions employed polymerize orV form sludge which tends to deactivate the catalyst and contaminate the reactants. Such undesirable compounds may be removed from feed stocks by conventional refinery methods such as by light acid treating, adsorption, and the like. Although the feed. stocks may contain alpha-olefin concentrations. as low as about 10% or so, it is desired that the stocks contain ajrnajor portion, preferably above 60 weight percent,I

ofsuch olens. Obviously the feed stock may'also con-1 tain other types of olens which may or may not be af'ected'in the isomerization step.

The-.advantage of the present invention is demonstrated 'bythe followingA specific examples of liquid phase, isomerizationruns:

EXAMPLE I An olefin feed stock containing about 96'weiglit per cent Cii to Ciaolens and about 2 weight per cent dioletinsv was employed' in this run. Sodium particles were addedto the feed. stock and the mixture was agitated at 120. C. in an Eppenbachl homogenizer in order to make adispersion comprising 2.1 weight per cent. sodium, based on'tlieolens, the sodium particles having a size in the rangefohabout 20; to; 50 microns. The temperature of the dispersion was. lowered and .was then agitated'for one hour at S23,a C., The reactantsl were filtered throughv Hi-flo (a diatornaceous filter aid)y and then through laboratory filter paperA to recover al product substantially free ofsodium and sludge.

EXAMPLE I I temperatureto another` portion of the `feedsti'selt to form a mixture containing l1.0 weight'peifcent"sodium` biisedI on the olens. -10 mol per centisopropyl alcohol, based It is seenthat Lsubstantial isomerizationofffype I olefins did not occur at temperatures below about 120 C. On the other hand significant shifting of the double bond to form Type II oletins having inthe range"Y of 11 to 19 on the sodium, was added to theiriixture as an activator. carbon atoms occurred at higher temperatures. The Cv The total mixture was then charged to` a bo'mb actuated and Cs olefins were not isomerized. by .a rocking mechanism and was agitated for 3,0 rninutes What is claimed is: d ,v at altemperature of 225 C. Thefprodu'ct was oooled, 1. The process of `isomerizing mono-olen hydrocarremoved from the bomb and filtered. L bons having at least about carbon atoms in the chain l0 which comprises the step of contacting said olefin with EXAMPLE m alkali metal at an active isomerization temperature of at The feed stock employed in this nm comprised 100% least about 150 C. whereby shifting of the double bond occurs octadecene oleiins. A sodium dispersion was prepared by l dispersing 11 weight per cent sodium in an aliphatic 1r 2. A procession isomerizing teritiinallyunsaturated hydrocarbon distillate boiling in the range vof about 310 a mono-olefin having m the Ina-nge of a ut 10 to. about 25 to 390 F Suflicient sodium concentrate was blended Carb0n.atm.s which cofnpnses tht? .Steps of intimately with the fed to obtain* a *mixture havin 0 5 weight er contacting said olens with finely divided alkali metal at cent sodium based ou theoctadecene-l irgi the feed stok a tempel-amm of at. least about 150 C" and below the 10 m01 er cem iso ro 1 alcohol based on the sodium' temperature at which substantial cracking of said olens was addd to the nliilzturley the mixture was heated to 225 20 occur Sep :a1-ating mtal fr0-m the reactants and recovering C. in a rocker bomb, and this temperature wasrmaintained a p31- odl ctgglglg limllrleoilrii ch the 31k au metal for 1/2 hour while agitating. The reactants were cooled is Sdun to room temperature and were filtered through acidtreated contact clay to'remove sodium and other solid 25 iste ggeesf zii/.51E tlskm whlch the temperature lnggls' The ital heatmg cycle was completed m 5. A process as in claim 2 in which the alkali metal .S' EXAMPLE IV is dispersed as finely divided molten particles in said olen. 6. A process for isomerizing Cin to C mono-alpha A feed Steele having a boiling range of 220 io 269 F. lens v vhih includesfhe Steps of Contacting tige Olens and comprising ehielly Ce alphaelens was prepared. A 1n the 11q111d phase wlth dlspersed Sodlurn .particles are concentrate was prepared containing 23 weight per cent temllefatulje 1n the fange Ofnbent 1.50" t0 425 C Said sodium dispersed in an aliphatic hydrocarbon distillate Sedlunl being Present 1n an amount 1n the fange 0f abeut boiling in the range of 310 to 390 F. and containing 0.01 to 20.0% by weight based on said olelns, separating 1.5 weight per cent carbon black and 1.5 weight percent 0d1l11n flfOIn the reactants, and recovering a Pl'Odl-et oleic acid based on the sodium. Suiiicient concentrate lnehldmg lntemalllf unstufated Otensg was added to the feed to obtain a 0 5 weight per cent 7. Piprocess as in claim 6 wherein said sodium particles concentration of sodium based on the olen. The mixhave dlametets belOW abqut 100 mlcffm3- ture likewise contained 10 mol per cent of isopropyl a1co 8- Proce5 as m clalm 7 Whefem Said lsomeflzauon hol based on the sodium. The mixture was agitated and s Gamed out 1n the Presence 0f about 1 t0 30 m01 Peffem heated at 225e C for hom., Cooled and filtered. based on said sodium, of an oxy hydrocarbon actviator having below about 10 carbon atoms. l

EXAMPLE V 9. A process as in claim 8 wherein said oxy hydrocari bon contains an active hydrogen. ifi 1'11n WS Carried Ont 1n the Same manner 0f that de 10. AY process for isomerizing Cii to C19 monosubsti- Sel'lbed 'In Example IV eXCePt that the Olenfeed Steek 45 tuted ethylenic hydrocarbons to internally unsaturated han a boltlng'fange 0f 170 t0 229 F- and Contained oleiins which includes the steps of forming a mixture chieyICi alpha-elens- The eaetlen temperature W comprising said olens dispersed sodium particles in an maintained at 200 C. for 1/2 hour. amount in the range of about 0.1 to 10% by weight based The feed StOCkS t0 end the Products frein the abeve on said oletns, and a small amount of an lalcohol having -runs were analyzed by mitra-red sppctrosraphw analytical 50 below about l0 carbon atoms, agitaiingsaid mixture in procedures. The analysis determined the concentration the vliquid phase at a temperature in the range of about of Type I OleIlS (mOnOSnbSttnted ethyleneS), Type II to 350 C. for a time sufficient to cause substantial oleiins (symmetrically disubstituted ethylenes) and Type isomerization, and removing sodium and other undesirable III oletins (unsymmetrically disubstituted, ethylenes). materials from the resulting product. The run conditions and `analytical data for each of the 5 1l. A process as in claim 10 wherein said sodium parexamples is shown'in Table I. lticles have diameters below about 100 microns.

Table I Example No I II III IV V Olen Feed stock used Cil-Ci Oli-Cin Cie C C1 Sodium. Weight Percent Based on Oletlns 2. 1. 0 0. 5 0. 6 0.5 Isopropyl Alcohol, Mol Percent Based on Sodium. 0 10. 0 10. 0 10. 0 10. 0 Olelc Acid, Wclght Percent Based on Sod1um 0 1. 5 0 1. 5 l. 5 Carbon Black. Weight Percent Based on Sodium. 0 1. 5 0 1. 5 1. 6 Run Conditions:

Temperature, C 93420 225 225 225 200 Contact Time, Hour 1. 0 0. 5 0. 5 0. 5 0. 5 Glenn Type Analysts, Weight Percent:

Feed Stock- Olean, Type I (0H =CHR) s7 a7 sa. e 75. c 77. s olenn, Type II (RCH=CHR) 4 4 4.5 5. e 7. 7 o1ann.1ype IIitCHi=Cl2m ls s 11.9 14.5 as

R Product- 01enn,'1ype I.-. Yil? 7 42.2 75.1 76.9 Olelin, Type II 4 80 40. 0 5. 4 7. 6 o1et1n,Type III 5 3 17.8 14.3 6.2

Claims (1)

1. THE PROCESS OF ISOMERIZING MONO-OLEFIN HYDROCARBONS HAVING AT LEAST ABOUT 10 CARBON ATOMS IN THE CHAIN WHICH COMPRISES THE STEP OF CONTACTING SAID OLEFIN WITH ALKALI METAL AT AN ACTIVE ISOMERIZATION TEMPERATURE OF AT

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