US3211803A - Process for the elimination of heavy alkylate - Google Patents

Description

Oct. 12, 1965 c. c. CHAPMAN 3,211,803

PROCESS FOR THE ELIMINATION OF HEAVY ALKYLATE Filed April 16, 1962 NNN INVENTOR. C C C H A PMAN BY ,al

3,211,803 PROCESS FOR THE ELlMINATION OF HEAVY ALKYLATE Charles C. Chapman, Bartlesville, Okla., assignor to Phillips Petroleum Company, a corporation of Delaware Filed Apr. 16, 1962, Ser. No. 187,481 1 Claim. (Cl. 260-683.49)

This invention relates to the catalytic production of higher-boiling hydrocarbons. More particularly, this invention relates to a method for the operation of an alkylaton system wherein the heavy alkylate produced therein is treated with isoparal'lin in the presence of catalyst to produce ,additional light alkylate therefrom. In one aspect this invention relates t-o a method of operation of lan HF alkylaton system to increase the yield of light alkylate and improve the alkylate quality by separating the total alkylate into a light and heavy alkylate and then recycling the heavy alkylate to extinction. In another .aspect of this invention there is provided a method of operating an alkylaton system so as to alkylate olens with isopentane in a primary yalkylaton zone in a manner so as to avoid the accumulation of heretofore insoluble heavier alkylates generally produced in same.

In many processes which have been proposed for converting low-boiling hydrocarbons into higher-boiling hydrocarbons such as the production of motor fuels and lubricants from less viscous, more volatile, normally gaseous hydrocarbons, there is generally produced a portion of the initial reactants which has a boiling point higher than that -generally preferred for compounds which possess good motor fuel properties. The total alkylate (butane-free) is generally composed of about 70 percent light ralkylate and is that portion having an end point below about 260 F., and yabout 30 percent heavy alkylrate is that por-tion having an intial boiling point of about 260 F. The light alkylate has .an octane rating higher than that of the heavy alkylate.

In addition, while alkylaton with isopentane is well known, the process is not generally practiced due to the excessive Iamount of heavy alkylate of low quality which is produced.

I have now found in .accord-ance with the present invention that such heavier higher-boiling .alkylate materials may be avoided by the separation of the alkylate from the reactor and recycling the por-tion of same boiling above the desired temperature with additional isoparain and catalyst. Such recycling serves to increase the overall amount of light alkylate and increases the octane rating of the resulting total alkylate.

Thu-s it is an object of this invention to produce higherboiling paraffin hydrocarbons by the alkylaton of lowerboiling paraiiins in such a manner as to give optimum yields of the desired alkylate fraction.

Another object of this invention is to provide a method for utilizing, Awhile achieving removal of, undesirable portions of alkylate material from yan .alkylaton system.

A still further object of this invention is to provide a desirable method for achieving .alkylaton using isopentane in such a manner as to avoid the accumulation of heavy ,alkylate which is normally experienced in the react-ion.

Other aspects, objects and the several -advantages of my invention and process will be found in the accompany-ing disclosure, drawing and appended claim.

As shown in the accompanying figure, which is illustrative of one embodiment of this invention, olefin is introduced by means of conduit 1 into alkylaton zone 2. Fresh isobutane is added to the alkylaton zone 2 by United States Patent O 3,21 1,803 Patented Oct. 12, 1965 means of conduits 3 and 4; Hydrocarbon reaction effluent is removed from alkylaton zone 8 by means of conduit 5 to fractionator 6 wherein the propane and ligh-ter content is removed overhead and isobutane and heavier components are passed by means of conduits 7 and 8 to deisobutanizer 9. Recycle isobutane is removed overhead and returned by conduits 10` and 4 to alkylaton zone 2. The residue of deisobutanizer 9 is passed by means of conduit 11 to debutanizer 12 wherein n-butane is taken overhead by means of conduit 13 and the remaining alkyla-te product is passed by means of conduit 14 to alkylate splitter 26 wherein a separation of theheavy and light components is achieved. Generally, the portion boiling below 260 F. is removed as overhead'by means of conduit 15 and the portion boiling above 260 F. is removed as bottoms through conduit 16. The specie separation of heavy and light portions m-ay be altered depending on the particular components desired. The bottoms product is returned by means `of conduits 16 and 17 to .a second alkylaton zone 18 wherein .additional isobutane is .added by means of conduit 19. VMake-up HF is introduced by way of conduit 20 and spent HF for rerun is removed by means of conduit 21. I A similar provision is made on alkylaton zone 2 in conduits 23` and 24 so as to allow the requisite HF catalyst to be introduced int-o and removed therefrom. Hydrocarbon rea-ctor euent from alkylaton zone 18 is removed by means of conduit 25 and combined with the bottoms product fromdepropanizer l6 and introduced into de-isobutanizer 9 wherein the heretofore described separation is carried out. h1 this manner the heavy ialkyla-te produced in alkylaton zone 2 is continuously circulated for consumption in alkylaton zone 18 vuntil extinct, and the heavy alkylates are ultimately removed, after being converted to light alkylate, as light alkylate throughY conduit 15 of splitter 26.

As another embodiment of this invention, if desired, other higher-boiling paraflinhydrocarbons not derived from the HFv alkylaton such as a rainite from the catalytic reforming of naphtha may be added to the heavy alkylate to alkylaton zone 18 by means of conduitZS. This rainite is a paraflinic (and isoparatli-nic) portion of reformate from a reform-ing operation wherein a naphtha charge stock boiling in the range Vof about 15 O-400 F. is reformed, using any of the well-known reforming processes, e.g., the Platformingwprocess.. 'lhe raffinate produced from the reformate is obtained by solvent extraction, using .any of the well-known solvent extraction processes, c g., Udex, to produce a highly aromatic extract and the above-referred-to raliinate which is added to alkylat-ion zone 18. While somewhat more dilute concentration may be used, I prefer to use HF acid in concentration greater than percent by weight, the other material being acid soluble oil, w-ater, dissolved hydrocarbons and uorides. Also substantially v percent hydr-oiiuoric acid, that is substantially or completely anhydrous hydrouoric acid or hydrogen fluoride, is very effective and is particularly adapted to the process. The process is .generally car-ried out'with the hydrocarbon material substantially in liquid phase; efficient reaction` results when sufficient hydrofluoric acid is employed to result in'a substantial saturation of the liquid hydrocarbon material with hydrogen uoride, and preferably sui'cient hydrogen iiuoride is'used to form a separate liquid Yphase which may be maintained, emulsified or intimately mixed with the hydrocarbon while reaction takes place. lIn most cases the hydrofluoric acid charge should be at least 10 percent of the total charge on a liquid volume basis;

' are the preferred olefins.

' the reaction.

`HF acid to hydrocarbon volume ratios range from about The reaction temperature may be varied over a wide range for any par-ticular reaction mixture but appears to be more dependent upon the paraflin hydrocarbon participating in the reaction. Thus, in general, I may carry out an alkylation process at temperatures between 0 and 300-400 F. For readily reacted paraffin hydrocarbons such as isobutane or isopentane a readily effective alkylation temperature is in the range of about 75-180 F.; and for less reactive parains, higher temperatures are necessary. The use of hydrofluoric acid has a distinct advantage in such cases in that it can be used under these more extreme conditions without promoting or entering into extensive undesirable side reactions.

lOlefins of a Wide range of molecular weights ,and struc- .tures are suitable for use in the alkylation of paraflins in the presen-ce of concentrated hydr-ofiuoric acid. One of the principal commercial applications is the production lof paraffin hydrocarbons in the motor fuel range from lower-boiling hydrocarbons. For this reason olefins of or fewer carbon atoms per molecule rare more often preferred. Of tihese, ethylene enters into la reaction less readily, 'especially in the absence of olefins of more carhon atoms per molecule. |Proplyene land/or bu-tylenes While pentenes are generally considered to be in the motor fuel boiling range, it will often be desirable to decrease the amount of C5 hydrocarbons in the ffinal product for reasons of volatility or a higher-boiling fuel of low vapor pressure may be desired, so that it Will not be unusual to use pentenes. Hexenes, heptenes, octenes :and the like fare more Ioten of greater value, although they are not to be excluded from the concept of this invention.

Ordinarily the process is operated in liquid phase under moderate superatmospheric pressure such .as between about 20 and 200 pounds per square inch gauge. Since the alkylati-on reaction represents a decrease in the total number of rnolecules, a certain .amount of pressure favors However, since the reactants are generally readily maintained in liquid phase with only moderate pressure, using a reaction temperature in the lower part of the range indicated, only sufficient pressure to insure liquid phase operati-on is generally adequate. When higher reaction temperaturesare used, higher pressures may also be used, and pressures as high as 150G-2000 p.s.i.g. or more may be nsed if desired. While such high pressures favor reaction, lower pressures are gener- .ally successfully used with the pronounced activity of hydrouoric acid to induce the alylation reaction. Since very moderate temperatures usually :suffice in the presence of hydroiiuoric acid, for thermodynamic reasons the pressures can accordingly be moderate and can of course be blow, as can be `shown by trial, to permit effective alkylation. In most instances, the process will be operated under a pressure between 50 .and 500 psig.

The reaction period during which olefin is introduced,

i reacted and consumed to produce eventually .an isoparaf- Example Y Olefin charge (1)(50-50 propylene-bu-tylenes),

b./h. 100 Fresh isobutane (3), b./h.* 190 Recycle isobutane (110), b./h.** =11 10 4 Alkylation zone 2:

Isobutane/olefin volume ratio 10:1 HF/hydnocarbon volume ratio 1:1 Pressure, p.s.i.g 150 Temperature, F. 100 Product (7), less iC4 and nC4, b./h. a 170 Research octane W./ 3 cc. TEL of a (170 Alkylation zone '1'82 Heavy alkylate (less recycle) (17), b./h. 50 Conversion per pass, percent Isobutane (19), b./h.*** 300 Isobutane/olefin volume ratio 6:1 HF/hydrocarbon volume ratio 1:1 Pressure, p.=s.i.g 150 Temperature, F. 150 Total light ,alkylate (15) (260 F. end

point), b./h 220 Research octane number (15), w./i3 ec.

TEL 104.0

n b./l1. light alkylate (260 F. end point) and 50 b./h. heavy alkylate (260 F. initial B.P.).

*Includes 70 b./l1. for alkylatlon zone 18 and 120 b./h. for alkylation zone 2.

*tlncludcs 230 b./l1. for alkylation zone 18 and 880 b./h. for allrylation zone 2.

***Includes 230 b./h. recycle isobutane.

When isopentane is the isoparafiin charged to the falkylation zone y2, the ratio of light alkylate to heavy alkylate 'by volume produced therein is about 60 to 40. The heavy `'alkylate of this operation is then converted into light alkyla-te in alkylation zone 18 using isobutane as the isoparaffin.

Reasonable variation and modifications can be made in accordance with this invention, the essence lof which is that there has been provided a process for producing a maximum quantity of higher octane light alkylate in an HF alkylation Which comprises initially lalkylating an olefin 'with an isoparafiin, separating the resul-ting total .alkyflate into a light and heavy fraction, treating said heavy fraction with addi-tional isoparaflin in the presence lof HF catalyst, separating the resulting mixture into a light .and heavy fraction, and returning said heavy fraction for additional treatment with said iso-paraffin 'and HF catalyst.

I claim:

A process for the elimination of heavy ialkyalte in an `HF ralkylation system which comprises introducing into a tirst `alkylation zone maintained at 'alkylation conditions an alkylatable parafiinic hydrocarbon and an alkylating olefinic hydrocarbon, introducing into a second alkylation zone maintained at alkylation condition-s the rafiiate lobtained from the catalytic reforming of a naphtha stock and the heavy alkylate derived from the fractionation of the combined efiiuents from said first and second alkylation zones, combining the resulting efiiuents from said first and second talkylation zones, separating the resulting combined efliuents into the light alkylate yand heavy alkyl- |ate components thereof, returning the separated heavy alkylate component as feed to said second alkylation zione, and thereafter recovering the Ilight components as a product ofthe process.

References Cited by the Examiner UNITED STATES PATENTS 2,368,063 l/45 Elliott 260-68362 2,370,030 2/'45 Goldsby 260-683.62 2,890,995 6/ 5 9 Findlay 26 0-683 .62 3,019,180 1/162 Schreiner et ral. 208-79 X 3,13 8,645 6/64 Hutchings 260-683 .'62 X ALPHONSO D. SULLIVAN, Primary Examiner.

Images