US2567283A - Method of manufacturing motor fuels by polymerization and alkylation - Google Patents

Description

2,567,283 FUELS LYMERIZATION AND ALKYLAT A. R. GOLDSBY METHOD OF MANUFACTURING MOTOR BY PO ION Original Filed June 25, 1958 Sept. ll, 1951 lwith these olen fractions.

patented Sept. 11, 195i UNITED STATES rPATENT OFFICE 2,567,283 METHOD OF MANUFACTURING MOTOR FUELS BY POLYMERIZATION ALKYLATION AND Arthur R. Goldsby, Beacon, N. Y., assigner to' The Texas Company, New York, N. Y., a corporation of Delaware Original application 3 claims. (C1. 26o-6832.4)

vtion of isoparafns, such as isobutane, with normally gaseous olens.

June 25, 1938, Serial No.; 215,736. Divided and this application January 26, 1944, Serial No. 519,759 f l This is a division of my copending application Serial No. 215,736, iiled June 25, 1938, for

Manufacture of Motor Fuels, now Patent No.

v2,420,369 dated May 13, 1947.

An important object of the invention is to alkylate an isoparaiiin with a selected type of `tions containing oleiins of the same number of carbon atoms and then an isoparafiin is alkylated The unsaturated hydrocarbons suitable. for treatment may comprise normally gaseous hydrocarbons resulting from the cracking of hydrocarbon oils or gases, the destructive hydrogenation of heavy hydrocarbons, the dehydrogenation of normally liquid or normally gaseous hydrocarbons; or, normally gaseous hydrocarbons resulting from special conversion operations, such as the synthesis of hydrocarbon oils from water gas. The isoparaffins may be normally gaseous or normally liquid, for example, isoparafns of not substantially higher boiling range than gasoline, for example, isobutane or isopentane.

The separation of the olens may be effected by the use of selective polymerizing agents, for example, an acid, such as sulfuric acid or phosphoric acid. Methods which are speciiically contemplated include the selective polymerization with a solid phosphoric acid catalyst of the type,V

and according to the method, described in the Ipatieff Patent No. 2,101,857, December 14, 1937. The alkylation operation is preferably conducted in the presence of sulfuric acid catalyst, in ac- I cordance with the general method disclosed in the of Korpi-Goldsby, Serial 18, 1937, now Patent No.

co-pending application No. 148,978, filed June I2,436,965 dated March 2, 1948.

The invention will be more clearly from the following description read in connecunderstood 'the invention when using as the selectivepolymerization of the olens by a catalyst `comprising phosphoric acid to selecwherein they are Vto a fractionator I5 wherein tion with the Vaccompanying drawing, which shows a diagrammatic sketch of apparatus suitable for carrying out the process of the invention. Figure 1 shows an apparatus for practicing a step of the process tively polymerize the olefins. The drawing is obviously diagrammatic and is subject to variations to accomplish the intended purpose of segregating the various olens in the hydrocarbon mixture and then selectively alkylating an isoparafiin, such as isobutane, with these separated olefin fractions or polymers thereof.

Referring to Figure l, the olefin charging stock which is preferably a hydrocarbon gaseous mixture comprising principally parafiins and monoolens of three and four carbon atoms is introduced from a suitable source Y of supply, not shown, through the line V5. in which is located a valve 0 and pump 1. The hydrocarbons are passed through a coil 9 located in a heater Ill heated under a suitable pressure to sufficient temperatures to selectively polymerize the isobutene when contacted with a solid 'phosphoric acidcatalyst comprising a calcined to 150 F.,- preferably about 100 F. and a pressure of about 50 to 100 pounds, preferably about pounds. The products are passed through the-transfer line I2 to catalyst chamber I3 in which is located the catalyst. While one polymerizin'g chamber is shown it is to be understood that any number, connected in series or parallel, may be used. In the polymerizer I3, the isobutene is selectively polymerized, or a cross polymerization of one mol of isobutene with one mol of normal butylene is obtained. In the case of such cross polymerization, somewhat more drastic conditions of temperature and pressure than given above are desirable. The reaction products are passed from the lower portion of the catalyst chamber I3 through the valve controlled line I4 the normally liquid hydrocarbons orpolymers are condensed and withdrawn from the lower portion thereof through the line II to be discharged from the Isystem through the branch line I8 or delivered through the line operation, more fully The normally gaseous contains the catalyst.

separation of the polymers, are withdrawn from the upper portion of the fractionator I 5 through the vapor line 22 and forced by the pump 23 to a coil 24 located in a heater 25. In the coil 24 the hydrocarbons are subjected to sufficient temperature and pressure to eifect polymerization of the normal butylenes in the presence of phosphoric acid catalyst. The temperatures in the coil 24 may be about 150 to 250 F., preferably about 200 F., and a pressure of 150 to 350 pounds, preferably about 250 pounds. The products from coil 24 are passed through the line 28 to a second polymerizer or catalyst chamber 38 wherein they are contacted under approximately the conditions prevailing in coil 24 with solid phosphoric acid catalyst. The reaction products are transferred from the catalyst chamber 30 through the valve controlled line 3| to a fractionator 32 wherein the polymers are separated and withdrawn from the lower portion thereof through the line 33. The polymers so withdrawn may be discharged from the system through the branch line 34 or passed through the line 35 for subsequent alkylation.

The normally gaseous hydrocarbons fractionated out in the fractionator 32 should be substantially free from C4 oleiins and may contain propylene together With ethylene, if any. These gases are passed from the top offractionator 3-2 through the line 31 to coil 38 located in the heater 40. Pressure may be reduced on these gases by means of the valve 4l and the temperature raised in the heating coil 38 to a point such that the propylene in the gases will be polymerized in the vapor phase when contacted with solid phosphoric acid catalyst. Temperatures should be above 250 F. and may be as high as 500 F., preferably about 400 to 500 F. Pressure may range from about 100 to 300 pounds per square inch. The products are transferred from the heater through the line 42 to the polymerization chamber 43 which In the Vpolymerization chamber the propylene is polymerized to form a large proportion of material falling within the gasoline boiling point range, for example hexenes. The polymerization products are conducted from the polymerization lchamber through the valve controlled line 45 to a fractionator 46 wherein the polymers are fractionated out and withdrawn from the lower portion thereof through the line 41. Any portion of these polymers may be discharged from the system through the valve controlled line 48. It is intended, however, that the polymers be conducted through the Valve controlled line 50 to be used as charge to an alkylation operation. The remaining normally gaseous hydrocarbons are discharged from Athe top of the fractionator 46 through the valve controlled line 52.

When operating on C3 and C4 hydrocarbon fractions, the gases discharged from the top of the fractionator will consist largely of propane and butanes. It may be desirable in some ycases vto condense a large portion of the butanes along with the nal polymer withdrawn from the -fractionator 46. These butanes may be utilized vto impart volatility to the nished gasoline or the isobutane therein may be utilized as a portion of the isoparans which are alkylated in the subsequent alkylation operation. If the charging stocks contain substantial quantities of Vhydrocarbons of lower boiling point than C3 hydrocarbons, for example, C2 hydrocarbons, includfing ethylene, it may vbe desirable to employ a fourth stage of polymerization in which the ethylene would be polymerized to produce an additional quantity of polymers useful as a source of olefins in the alkylation operation. By using suitable time, temperature and pressure conditions, for example, temperatures of 550 to 700 F., pressures above 300 pounds and a contact time of at least 300 seconds, the ethylene may be polymerized to polymers which may be used for alkylation. Such a fourth stage of polymerization is not shown on the drawing.

The polymers withdrawn through the lines 20, 35 and 50, referred to heretofore, are discharged into suitable receivers or tanks 54, 55 and 56 respectively. These tanks are provided with valve controlled draw-off lines 5E, 59 and 60 for charging the contents thereof to an alkylation system. For the purpose of utilizing these stocks as alkylation charges, they may be passed into the line 6l and forced by the pump 62 to an alkylation vessel 10. In this vessel the olens are contacted with the necessary amount of isoparafn which may be introduced through the line 65 by the pump 66, and with a suitable quantity of an acid catalyst, introduced through the line 51 by pump 68. The isoparaflin, such as isobutane, is introduced in such amount that the ratio of isobutane to olefin in the reaction mixture is in excess of 1:1 and preferably between about 321 and 5:1. The catalyst is preferably sulfuric acid of alkylation strength and preferably about 94 to 98%. The amount of acid may be 50G-800% by weight based on the olen and the major part thereof may be recycled.

The mixture is transferred from the vessel 10 through the line 12 to a second alkylation vessel 14. In these tanks suiicient time is provided to effect substantial alkylation of the parains by the olens, for example, about 45 to 90 minutes and preferably about 50 to 60 minutes. The alkylation tanks are provided with means for producing as intimate contact as possible between the acid and the hydrocarbons by the use of stirrers 15 and 18 or other suitable mechanism. While two alkylation tanks are shown, it is to be understood that any number may be used, and the operation may be modied to use the counterflow principle for contacting the acid and the hydrocarbons, if desired. The reaction products are conducted from the last alkylation tank through the line 11 to a separator 18 wherein separation is allowed to take place between the acid and the hydrocarbons. If desired, any portion or all of the reaction products instead of being charged into the separator may be recirculated through the by-pass line 19 and the line containing pump -8I to the alkylation operation. The acid separating out in the separator 18 may be withdrawn from the system through the valve controlled line 82. It is preferable, however, to recycle a portion or all of this acid to the alkylation'operation through the lines 83 and 80.

The hydrocarbons settling out in the separator 18 are passed through the line 85 to a mixer 86 wherein they are intimately contacted with a neutralizing agent, such as an aqueous alkali, for example, dilute soda ash, introduced through the `line 81 by the pumpf88. The products are passed from the mixer 86 through the line 89 to a separator 90 wherein the neutralizer separates from the hydrocarbons and may be withdrawn through the line 9| or recycled to the mixer 86 through the lines /92 and 81. The neutralized hydrocarbons are conducted from the separator SII-through the line 94 vto a fractionator 95 wherepresence agaeaass in the normally liquid hydrocarbons' are fractionated to separate any low boiling normally gaseous hydrocarbons unsuitable for use-as gasoline. These normally gaseous. hydrocarbons are discharged from vthel top of the fractionator through the valve controlled line9`6. The liquid hydrocarbon fraction is withdrawn from the lower portion of the fractionatorthrough the line 91 andV discharged into a secondary fractionator 98 wherein the liquids are fractionally distilled to separate. as a liquid residue, the high-boiling liquids or bottoms, of higherboiling range than gasoline, which are withdrawn from the lower portion Yof the fractionator through the valve controlled line |00. Ijhe( vaporsfcontalining the gasoline are conducted overhead through the vapor line vto a ,condenser |02 wherein the vapors are condensed and the condensate passed through the run-down line 03 to an accumulator|04.

While only one alkylation unit' is showntfor the treatment of the various olefinic polymers from the separate stages of polymerization, it is contemplated that any number Yof alkylation units may be used, for example, one for each polymer fraction. Multiple injectionuof the olefms or polymers into two or more of the alkylation tanks may be used to improve the yield and quality of the product. It is to be understood that various mixtures of the separate polymers may be utilized, if desired, as a charging stock to the alkylation operation. Moreover, if desired, the separate polymers may be blended as desired and the blend utilized as a charging stock to the alkylation operation.

The alkylation operation is preferably carried out in the liquid phase which may be obtained by applying sufficient pressure, for example, about 25 to 150 pounds, to maintain the products in the liquid phase. The temperatures ordinarily employed range from about zero to 125 F., preferably about 60 to 90 F. If the various polymers are alkylated separately, the temperature and pressure conditions may be regulated to obtain optimum results, from the standpoint of yield and antiknock Value.

In the foregoing description of the process of the invention, normally gaseous olefins are selectively polymerized in the vapor phase to obtain oleflnic polymers which are in general normally liquid products. These normally liquid products are used in the alkylation of isoparains, such as isobutane, to obtain branch chain hydrocarbons Within the gasoline boiling range and having a high antiknock value.

As an example of tion, unsaturated hydrocarbon gases from a cracking still, comprising essentially C3 and C4 hydrocarbons, were subjected to polymerization by contacting them with a phosphoric acid catalyst comprising a calcined mixture of pyrophosphoric acid and kieselguhr. The temperature was about 100 F. and the pressure about Y 100 pounds. A polymer Was separated comprising largely di-isobutylene. The unreacted gases were subjected to further polymerization in the of a similar catalyst, at temperatures of about 200 F. and 250 pounds pressure, whereby the isomeric butenes were polymerized and separated as a polymer. The unreacted gases were further subjected to polymerization in the presence of a similar catalyst at temperatures of about 500 F. and a pressure of about 250 pounds to polymerize the propylene which was separated as a polymer. The three polymers were separately subjected to an alkylation reaction in the the operation of the inven-l 4presence of isobutane and sulfuric acid of about 96% concentration. A gasoline fraction was separated from each of the polymerization products. The gasoline from the treatment of the di-isobutylene had an octane rating of about 92 and contained a substantial amount of iso-octane. The gasoline from the alkylation of the isomeric butene polymer had an octane rating of around 90 and also had a substantial iso-octane content. The gasoline obtained from the alkylation prod ucts utilizing the propylenev polymer had an octane rating of about and contained a substantial amount of viso-heptane.

An advantage of the present invention is the alkylation of relatively pure oleflns which often produce increased yields over those possible when treating the mixtures of olens. Furthermore, it is possible to produce from the various olefins, different types of alkylation products, which are often desirable as special fuels or as blending agents to improve the antiknock and volatility characteristics of certain fuels.

Obviously many modications and variations of the invention, as heretofore set forth, may be made Without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. In the manufacture of substantially saturated gasoline hydrocarbons from a renery hy drocarbon fraction containing a mixture of different olens, the method comprising selectively and separately polymerizing a plurality of said oleflns and separately recovering a plurality of, the resultant olefin polymers, blending a pro portion of one of the separately. recovered poly-- mers with at least one other separately recovered polymer, and alkylating an isoparaflin with the polymer blend in the presence of an acid alkylation catalyst under alkylating conditions includ-` ing the maintenance throughout the entire re action of a substantial molar excess of isoparafm to monomeric olen equivalent of the said olefin polymer to produce subtantially saturated gaso line hydrocarbons.

2. A process for the production of alkylated hydrocarbons from a hydrocarbon mixture containing normally gaseous olefin hydrocarbonsl having diiferent molecular Weights, which comprises subjecting the said mixture to conditionsl of polymerization adapted to polymerize substantially all of the olefin hydrocarbons of one molecular weight contained in said mixture without substantially polymerizing olen hydrocarbons of a different molecular Weight and thereby selectively polymerizing said olefin hydrocarbons of said one molecular Weight, separating substantially all of said polymerized olen hydrocarbons from the unpolymerized olen hydrocarbons to thereby separate said mixture into fractions containing said olen hydrocarbons of the same molecular Weight, subjecting said separated unpolymerized olen hydrocarbons to polymerization, and utilizing the separate olefin polymers to form separate alkylates by separately alkylating each with an isoparain in the presence of an alkylating catalyst at different optimum temperatures adapted to produce the greatest yield of alkylated hydrocarbons therefrom.

3. A process for the production of alkylated hydrocarbons from a hydrocarbon mixture containing olen hydrocarbons consisting essentially of propylene and butylene which comprises subjecting said mixture to conditions of polymerizaeinem@ `tionadapted,to polymer-ize subtantially allof the butylene contained lin said mixture without sub.- s'tantially polymerzing said propylene andthere.- by selectively .polymer-ming vsaid butyl'ene, sep;- arating substantially all of the polymerized butylene from the propylene and thereby separating said. mixture into fractions containing said ole# lint-hydrocarbons of the same molecular weight, subjecting said separated. propylene to polymerization., and utilizing the separate butylene polymer and. propylene polymerrto form separate alkylates by. separately alkylating each with an soparan in the presence of an alkylatingv catal-ystv at. diler'ent optimum temperatures adapted toproduce the greatest yield of alkylated hydro'- allbons therefrom.

ARTHUR R. GOLDSBY.

REFERENCES CITED The following referencesV are of reor'd iii the le of this patent:

FOREIGN PATENTS F NV. 1.8, 1937

Claims (1)

1. IN THE MANUFACTURE OF SUBSTANTIALLY SATURATED GASOLINE HYDROCARBONS FROM A REFINERY HYDROCARBON FRACTION CONTAINING A MIXTURE OF DIFFERENT OLEFINS, THE METHOD COMPRISING SELECTIVELY AND SEPARATELY POLYMERIZING A PLURALITY OF SAID OLEFINS AND SEPARATELY RECOVERING A PLURALITY OF THE RESULTANT OLEFIN POLYMERS, BLENDING A PROPORTION OF ONE OF THE SEPARATELY RECOVERED POLYMERS WITH AT LEAST ONE OTHER SEPARATELY RECOVERED POLYMER, AND ALKYLATING AN ISOPARAFFIN WITH THE POLYMER BLEND IN THE PRESENCE OF AN ACID ALKYLATION CATALYST UNDER ALKYLATING CONDITIONS INCLUDING THE MAINTENANCE THROUGHOUT THE ENTIRE REACTION OF A SUBSTANTIAL MOLAR EXCESS OF ISOPARAFFIN TO MONOMERIC OLEFIN EQUIVALENT OF THE SAID OLEFIN POLYMER TO PRODUCE SUBSTANTIALLY SATURATED GASOLINE HYDROCARBONS.

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