US2221846A - Solvent refining of motor fuels - Google Patents

Description

Patented Nov. 19, 1940 UNITED STATES SOLVENT REFINING F MOTOR FUELS Wilbur B. Pings, Wilmington, Del., assignor to E. I. du Pont de Nemoul's & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application June 30, 1939; Serial No. 282,072

17 Claims.

This invention relates to the solvent refining of motor fuels and more particularly to. the production of motor fuels of relatively high knock rating from motor fuels having relatively low knock rating.

'Motor fuels derived from crude petroleum oils by direct distillation, known as straight-run gasolines, are in general too low in octane value to be used per se in the high compression engines of today. These fuels, as well as the cracked gasolines and polymer gasolines, are ordinarily composed of mixtures of paraffinic, naphthenic, aromatic and unsaturated aliphatic constituents which vary widely in their resistance to knocking in high compression internal combustion engines. It is generally desirable to improve the knock rating of such motor fuels or to obtain therefrom motor fuels of higher knock rating. I have found that, by solvent refining such mgtor fuels employing a certain type of solvent, I can separate, from such motor fuel mixtures, the constituents of relatively high knock rating.

It is Well known that the more viscous petroleum oils can be refined by means of solvents to separate the relatively non-paraffinic constituents from the relatively paraflinic constituents. Many solvents have been proposed therefor and have been employed successfully. Many of such solvents cannot be employed with the non-viscous oils of motor fuel boiling range, as they will not form the essential two phases at obtainable temperatures, or cannot be separated from the several fractions of the motor fuel.

It is an object of my invention to provide a method of treating a non-viscous, normally liquid hydrocarbon oil of motor fuel boiling range containing relatively parafllnic and relatively non-paraflinic hydrocarbons to separate the relatively non-paraffinic hydrocarbons from the relatively paraflinic hydrocarbons. Another object is to extract the relatively non-parafiinic hydrocarbons from a non-viscous,-normally liquid bydrocarbon oil of motor fuel boiling range by means of a selective solvent. A further object is of improved knock rating from a non-viscous, normally liquid petroleum oil of motor fuel boiling range, which comprises a mixture of hydrocarbons of different knock ratings by extracting the hydrocarbons of relatively high knock rating therefrom by means of a selective solvent. A still further object is to provide a method of producing a motor fuel of improved knock rating from a straight-run gasoline. Other objects are to improve the art. -Still other objects will appear hereinafter.

These objects may be accomplished in accordance with my invention, which comprises subjecting a non-viscous normally liquid hydrocarbon oil of motor fuel boiling'range containing relatively to provide a method of producing a motor fuel parafiinic and relatively non-paraffinic hydrocarbons to a solvent extraction step, employing as the extraction solvent a di-alkoxyalkyl phthalate in which each alkoxyalkyl group contains only two to six carbon atoms. I have found that such alkoxyalkyl phthalates will extract the relatively non-paraffinic hydrocarbons from such bydrocarbon oil and'will extract the hydrocarbons of relatively high knock rating from a non-Viscous normally liquid petroleum oil of motor fuel boiling range which comprises a mixture of hydrocarbons of different knock ratings.

The hydrocarbon oils, which may be treated in accordance with my invention, are those generally known as non-viscous normally liquid hydrocarbon oils of low molecular weight which are suitable for use in internal combustion engines. They will generally have the following characteristics:

% distillation point-not over 200 F. 90% distillation point-not over 395 F. End distillation point--not over 450 F.

The hydrocarbon oils will generally be of petroleum origin, such as the straight-run gasolines, cracked gasolines, reformed gasolines and polymer 'gasolines, which oils of petroleum origin will be hereinafter referred to as petroleum oils.

The solvents, to be employed in accordance with my invention, are the di-alkoxyalkyl phthalates in which each alkoxyalkyl group contains only two to six carbon atoms. They are di-alkoxyalkyl esters of phthalic acid. Preferably, the alkoxyalkyl radical or group contains only three to four carbon atoms. Also, the di-methoxyalkyl phthalates in which each alkyl group contains only two to three carbon atoms produce the best results. Amongst the compounds which I have found to be particularly satisfactory are:

Di-methoxyethyl phthalate Di-methoxypropyl phthalate Di-butoxyethyl phthalate The di-methoxyethyl phthalate becomes miscible only at about 90 C. and permits phase separa-. tion at temperatures of about 25 C. and lower. The di-methoxypropyl phthalate permits phase separation at about 0 C. The di-butoxyethyl phthalate permits phase separation at about 50 C. and is applicable for extractions at low temperatures. Alkoxyalkyl phthalates of intermediate numbers of carbon atoms will permit phase separation at intermediate temperatures.

In general, the method of my invention will comprise mixing approximately equal volumes of solvent and hydrocarbon oil and heating with agitation to a temperature at which the solvent and oil become completely miscible. The solution will then be cooled with agitation to a temperature substantially below the temperature of lit complete Upon set lg, layers will be f..n .1fl@d which separated, and

tillation :51 m the solvent, one or comprises components of the motor fuel d solved in the bulk oi. the liquid solvent, while the other icons of rel rocar'bons atively sigh knock: ratin she from. the is, er containing the sma amount of solvent comprises primarily the rela ely paratrfinic constituents of low octane number and low knock The motor fuel, from the layer containing the larger amount solvent, the extract phase, may be employed per se as a high anti-knock; motor fuel or it may be used for blending with an ordinary petroleum naphtha to increase the octane value or knock rating of the naphtha. it may be used without further reing, if desired, or it maybe subjected to any DI the usual refining treatments, such as disti1lation and the like.

Before subjecting the oil to the extraction treatment, it will generally be desirable to top it of light ends to 95 C., that is, to boil off the constituents boiling below 95 C. This is done to avoid handling losses of gasoline by volatilization, as the light ends are generally satisfactory as to lrnock rating.

the example given below, the selective re moval of the high anti-knock constituents from a motor fuel has been measured by following the change in refractive index and aniline pointer the gasoline. The values of these constants for difierent hydrocarbon types is described in an article by F. D. Rossini in the Oil and Gas Journal, volume 36, November 12, 1937, page 193 et seq, entitled A decade ,of research on the chemical constitution of petroleum. The values of the refractive index increase in the order paraffin, naphthene, and aromatic, and for molecules with 8 or 9 carbon atoms have the following approximate values: parafin 1.40; naphthene 1.425; aromatic 1.50. The critical solution temperature in aniline increases in the order aromatic, naphthene, and parafiin, and for molecules with about 8 carbon atoms has the following approximate values, respectively: 2il (3., 415 C. and 7l C. The aniline points of a large number of pure hydrocarbons will also be found in an article. by E. B. Evans entitled Aniline points of hydrocarbons in the Journal of the Institution oi Petroleum Technologists, volume 23, page 22c et seq. An increase m the refractive index and a decrease in the aniline point will thus indicate a segregation of the desirable types largely responsible for high octane value.

In order to minimize handling losses, selective solvent extraction is preferably applied to gasolines having an initial boiling point of about 200 F. (93 C.), which will in general necessitate a preliminary topping operation.

Example cooled arge proportion oi co al. volume of diqiethoxyethyl p heated to 52., which temperate and gasoline were im'scible. The so :o 5 allowed to settle, U W ndrawn recovered from both layer on reduced pressure. The solvent to contain 8% by volume of the line. The extract had a refractive index at of 1.4461, compared with a value of lxlficii b Sore .3

extraction, and an aniline point of l2.l. 6., com" pared with a value of 430 C. before extractio The above example is merely illustrative of r ntion and my invention is not to be thereto. I be made "in the process and the conditions em ployed Without departing from the spirit of invention. Also, other di'alkoxyallryl phthalates may be substituted for the di-methoxyethyl phthalate. phthalates are:

Di inethoizymethyl phthalate Di-methoxybutyl phthalate Di-ethoxymethyl phthalate Di-ethoxyethyl phthalate Di-ethoxypropyl phthalate Di-ethoxybutyl phthalate Di-propoxymethyl phthalate Di-propoxyethyl phthalate Di-propoxypropyl phthalate Dl-butoxymethyl phthalate Also, di-alkoxyalkyl phthalates, containing two different allzoxyaliryl groups, maybe employed.

Further, mixtures of two or more difierent din and doctor treatment applied either before or after the solvent extraction. Also, the conditions of the applicationof the solvent may vary with the nature of thegasoline being treated and the improvement in anti-knock rating desired. It may be desirable to carry out the extraction with a relatively large volume of solvent, for example several hundred percent. In some cases, it may be desirable to carry out the extractionwith less than equal volume of solvent. However, approximately equal volumes of solvent and gasoline will usually be employed. The solvent and gasoline may be mixed and separated in a batch operation or in a countercurrent operation. the temperature for the formation of two phases may vary, depending upon the particular gasoline and solvent selected, but will generally range from about l0 C. to about 50 C. v

My invention has the advantage of providing stable neutral solvents which will have no tend-= ency to react with the constituents of the gasoline. The solvents have boiling points sufiiciently high to permit separation or the gasoline therefrom by a simple distillation. The solvents have mis cibility characteristics which permit them to be employed without other materials such as precipitants and the like. As compared with my compounds, other somewhat related alkoxyallryl variations and modifications may 1 Some of such other di=-alkoxyalhyl esters, such as di-butoxyethyl fumarate, di=- butoxyethyl succinate and di-butoxyetlryl adipate, 75,

do not form twophases with the gasoline of the example at temperatures even as low as -50 C.

I claim:

1. The method of treating a non-viscous normally liquid hydrocarbon oil of motor fuel boiling range containing relatively parafiinic and relatively non-parafiinic hydrocarbons which comprises extracting the oil in the liquid phase with a di-alkoxyalkyl phthalate in which each alkoxyalkyl group contains only two to six carbon atoms, to separate the relatively non-parafiinic hydrocarbons from the relatively paraflinic hydrocarbons.

2. The method of treating a non-viscous normally liquid hydrocarbon oil of motor fuel boiling range containing relatively paraflinic and relatively non-paraflinic hydrocarbons which comprises extracting the oil in the liquid phase with a di-alkoxyalkyl phthalate in which each alkoxyalkyl group contains only three to four carbon atoms, to separate the relatively nonparafilnic hydrocarbons from the relatively paraffinic hydrocarbons.

3. The method of treating a non-viscous normally liquid hydrocarbon oil of motor fuel boiling range containing relativelyparaflinic and relatively non-paraflinic hydrocarbons which cornprises extracting the oil in the liquid phase with a di-methoxyalkyl phthalate in which each alkyl group contains only one to four carbon atoms, to separate the relatively no-paraflinic hydrocarbons from the relatively paraffinic hydrocarbons.

4. The method of treating a non-viscous normally liquid hydrocarbon oil of motor fuel boiling range containing relatively paraiiinic and relatively non-parafiinic hydrocarbons which comprises extracting the oil in the liquid phase with a di-methoxyalkyl phthalate in which each alkyl group contains only two to three carbon atoms, to separate the relatively non-paraflinic hydrocarbons from the relatively paraiilnlc hydrocarbons.

5. The method of treating a non-viscous normally liquid hydrocarbon oil of motor fuel boiling range containing relatively paraiiinic and relatively -'non-paraffinic hydrocarbons which comprises extracting the oil in the liquid phase with a di-alkoxyethyl phthalate in which each alkoxy group contains only one to four carbon atoms, to separate the relatively non-paraflinic hydrocarbons from the relatively paraiiinic hydrocarbons.

6.. The method of treating a non-viscous nor mally liquid hydrocarbon oil of motor fuel boiling range containing relatively parafilnic and relatively non-paraflinic hydrocarbons which comprises extracting the oil in the liquid phase with a di-alkoxyethyl phthalate in which each alkoxy group contains only one to two carbon atoms, to'separate the relatively non-paraflinic hydrocarbons from the relatively paraflinic hydrocarbons. V

7. The method of treating an non-viscous normally liquid hydrocarbon oil of motor fuel bolling range containing relatively paraflinic and relatively non-paraflinic hydrocarbons which comprises extracting the oil in the liquid phase with di-methoxyethyl phthalate, to separate the relatively non-parafflnic hydrocarbons from the relatively paramnic hydrocarbons.

8. The method of treating a non-viscous normally liquid hydrocarbon oil of motor fuel boiling range containing relatively paraflinic and relatively non-parafiinic hydrocarbons which comprises extracting the oil in the liquid phase with di-methoxypropyl phthalate, to separate the relatively non-paraffinic hydrocarbons'from the relatively paramnic hydrocarbons.

9. The method of producing a motor fuel of improved knock rating from a non-viscous normally liquid petroleum oil of motor fuel boiling range comprising a mixture of hydrocarbons of different knock ratings which comprises mixing the oil in the liquid phase with a di-alkoxyalkyl phthalate in which each alkoxyalkyl group contains only two to six carbon atoms, forming an extract phase containing hydrocarbons of relatively high knock rating dissolved in the phthalate and a raffinate phase comprising hydrocarbons of relatively low knock rating, separating the two phases and removing the hydrocarbons from the phthalate.

10. The method of producing a motor fuel of improved knock rating from a straight-run gasoline which comprises extracting the gasoline in.

the liquid phase with a di-alkoxyalkyl phthalate in which each alkoxyalkylgroup contains only two to six carbon atoms to separate the compounds of higher knock rating from the gasoline.

11. The method of producing a motor fuel of improved knock rating from a straight-run gasoline which comprises extracting the gasoline in the liquid phase with a di-alkoxyalkyl phthalate in which each alkoxyalkyl group contains only three to four carbon atoms to separate the compounds of higher knock rating from the gasoline.

12. The method of producing a motor fuel of improved knock rating from a straight-run gasoline which comprises extracting the gasoline in the liquid phase with a di-methoxyalkyl phthalate in which each alkyl group contains only two to three carbon atoms to separate the compounds of higher knock rating from the gasoline.

13. The method of producing a motor fuel of improved knock rating from a straight-run gasoline which comprises extracting the gasoline in the liquid phase with a di-alkoxyethyt phthalate in which each alkoxy group contains only one to two carbom atoms to separate the compounds of higher knock rating from thegasoline.

14. The method of producing a motor fuel of improved knock rating from a straight-run gasoline which comprises extracting the gasoline in the liquid phase with di-methoxyethyl phthalate to separate the compounds of higher knock rating from the gasoline. v

15. The method of treating a non-viscous normally liquid hydrocarbon oil of motor fuel boiling range containing relatively paraflinic and relatively non-parafiinic hydrocarbons which comprises extracting the oil in the liquid phase with di-butoxymethyl phthalate, to separate the relatively non-paraillnic hydrocarbons from the relatively parafllnic hydrocarbons.

16. The method of producing a motor fuel of improved knock rating from a straight-run gasoline which comprises extracting the gasoline in the liquid phase with di-butoxymethyl phthalate CERTIFICATE OF CORRECTION. Patent No. 2,221,814.6- November 19, 191 0.

WILBUR B. PINGS.

It is hereby certified that error appears in the printeqi specification of the above nnmbered patent requiring correction as follows: Page 5 first column, line 51, claim3, for "noparaffinic" reed --non-p'araffinic--; line 634., claim 7, for "an" read -a--; and second column, line 69; claim 17, for "improced" read --improved; and that the said Letters Patent should be read with this correction therein'that the same may conform to the record of the case in the Patent Office.

Signed and sealed this al en day of December, A. D. 191 0.

Henry Van Arsdale, (Seal) Acting Comniissioner of Patents