US2161625A

US2161625A - Chemical process

Info

Publication number: US2161625A
Application number: US184969A
Authority: US
Inventors: Harold S Holt
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1938-01-14
Filing date: 1938-01-14
Publication date: 1939-06-06
Anticipated expiration: 1956-06-06

Description

Patented June 6; 1939 UNITED STATES PATENT OFFICE CHENHCAL PROCESS No Drawing. Application January 14, 1938,- Serial No. 184,969

11 Claims.

This invention relates to the separation of mixtures of hydrocarbons by selective solvent extraction and more particularly to the solvent refining of mineral oils.

It is now well known that a large proportion of the mineral oils and gasolines of today are complex mixtures of paraflinic and non-paraflinic hydrocarbons. It is frequently desirable to separate the non-paraflinic hydrocarbons from the paraiiinic hydrocarbons for various reasons; One

of the main reasons is that the parafiinic hydrocarbons are in general more resistant to decomposition through heat and oxidation than the nonu parailinic hydrocarbons. Accordingly, the oil containing the larger proportion of parafiinic constituents or, in other words. the relatively more paraflinic oils are more stable than the less perafllnic oils and hence are more desirable as lubricants and for other purposes.

Various methods have been proposed for separating the non-parafllnic from the paraffin c constituents of oils. One of the more common and oldest is by treatment with sulfuric acid wh ch removes some of the non-paraillnic compounds 25 from the oils. More recently it has been proposed to separate the non-paraifinic hydrocarbons by means of selective solvent extraction.

An object of the present invention is to provide a method for separating a mixture of paraffinic 30 and non-paraiilnic hydrocarb ns nto portions. one of which is relatively more parafiinic than the original mixture and the other relatively less parailinic. Another object is the separation of relatively non-paraffinic bodies from mineral lu- 5 bricating oils to produce lubricating oils of relatively high paraflinic character. A further object is the production of lubricating oils with improved viscosity-temperature curves from oils with poor viscosity-temperature curves. Still other objects 40 will appear hereinafter.

These objects may be accomplished in accordance with my invention which comprises treating the mixtures of parafilnic and non-paraflinic hydrocarbons with an alcohol having the follow- 46 ing general formula:

R1 R('JOECH I n 0 in which R and R1 may be hydrogen atoms of hydrocarbon radicals and the total number of carbon atoms in R and R1 taken together when either or both are hydrocarbon radicals is less 55 than 7.

The hydrocarbon mixture or oil is mixed with a solvent comprising an alcohol of the formula noted above under such conditions that two layers are formed: one of which com rises the constituents which it is desired to extract from the oil dissolved in the bulk 01' the solvent. and the other layer compr ses the undissolved and relatively parafllnic hydrocarbons in admixture with a relatively small amount 01' the solvent. Preferably. my method comprises mixing the said alcohol and hydrocarbon mixture in approx mately eoual volumes and heating same with a itation at the temneratui'e at wh ch the solvent and oil become completely miscible. This solution is then cooled while agitating and the cooling continued to a t mperature at least below the temperature of complete miscibility. The'resultin mixture is then allowed to stand until it separates intn two layers. These layers are separately withdrawn and the alcohol recovered from each b d stillation, preferably under reduced pressure. The residue from the layer containing the lair-oer amount, of solvent consists oi a lar e portion of the n nparafilnic constituents: whereas t e layer containing a smaller amount nf solvent consists primarily of the parafnnic constituents.

In the examples given bel w. the selective removal of non-paraifinic constituents fr m a m neral oil has been measured by fnllnwing the change in viscosity-gravity constant. of the nil. This constant has been described hv .l. B. Hill and H, B. Coates in Industrial and Engineering Chemistry, volume 20. page 641. et. seq.. in an article entitled "The Viscosity-Gravitv Constant nf Petroleum Lubrica in O s. Ti :1 iv n crude petroleum be distilled int succ ssive fractions and the specific gravities and viscnsities of the, several fractions determined. it will be found that they conform to the general relationship:

in which "(3" is the specific gravity at 60 F.. "V" is Saybolt Universal viscosity at 100 F., and "a" is the viscosity-gravity constant. These constants are lower for fractions of the naphthcnc crudes. The viscosity-gravity constant is. therefore, an index of the parafiinicity oi an oil. and a decrease in the value of this constant for a given fraction of lubricating oil indicates an increase in paraffin hydrocarbon content.

The following examples set forth certain well defined instances of the application of this invention. They are, however. not to be considered as limitations thereof,.since many varia' log (V-38) tions may be made without departing from the spirit and scope of this invention.

Example 1 A lubricating oil distillate (with the following characteristics: viscosity at F., 566 secs. Saybolt Universal; specific gravity at 60 F./60 F., 0.927; viscosity-gravity constant, 0.872;

35 1.5140) was mixed with an equal volume of dimethyl ethynyl carbinol, heated with agitation to 100 C. at which temperature solvent and oil were miscible, the solution cooled to 25 C., allowed to settle, and the two layers withdrawn into separate containers. Dimethyl ethynyl carbinol was removed from both layers under reduced pressure. The top layer was found to contain '70 percent 01 the volume of the original oil, which had the following characteristics: viscosity-gravity constant,

Example 2 The lubricating oil distillate given in Example 1 washeated to 50 C. with an equal volume of isopropyl ethynyl carbinol with agitation, cooled to 20 C., and allowed to settle 15 hours. The two layers which formed were treated as in Example 1, with an oil recovery in the bottom layer of 72.

per cent. This oil had characteristics as follows: viscosity-gravity constant, 0.858;

Example 3 The distillate used in Example 1 was mixed with an equal volume of methyl ethyl ethynyl carbinol at 35 C. and then allowed to settle 15 hours at approximately 4 C. After separation and removal of the solvent from each layer, an oil recovery of 73 per cent was obtained from the top layer. This oil had the following characteristics: viscosity-gravity constant, 0.868;

Example 4 A solvent was prepared by mixing one part of methyl ethyl ethynyl carbinol with one part of beta-beta dichlorodiethylether. The lubricating oil distillate given in Example 1 was heated with an equal volume of this mixed solvent to 30 0., the temperature of complete miscibility. The solution was cooled to 5 C., settled four hours, and the separated layers treated as in the previous examples. From the top layer a yield of '73 per cent of oil was obtained having a viscositygravity constant of 0.855. Under the same conditions 01 treatment, equal volumes oi the lubricating oil distillate and dichlorodiethyl ether were miscible only at the higher temperature 0! 55 (3., the yields of oil in this case being 71.6 per cent and the viscosity-gravity constant being 0.856.

As examples or other alcohols which fall within the class adapted tor use in this process, one may use methyl ethynyl carbinol (B. P. l0'7-109 (1.), ethyl ethynyl carbinol (B. P. 122-125 C.), and ethnyl cyclohexanol (B. P. 97-103 C./65 mm.).

The conditions of application of the solvent will vary with the nature of the oil, highly naphthenic oils in general requiring a lower temperature of separation than highly parafiinic oils. The temperatures employed, however, may be expected to range from about 0 C. to 200 C. or thereabouts. For some oils they may be expected to be somewhat lower than 0 C. The volume ratio 01' solvent to oil may be varied within wide limits and will be determined by the nature of the crude distillate and by the quality desired in the refined oil. In general, the limits of the ratio of solvent to oil may lie between about 1:10 and about 5:1. Application 01' the solvent is not limited, of course, to single batch extractions but may employ any other suitable means, for example, countercurrent extraction. Extraction with ethynyl carbinols need not be confined to lubricating oil distillates but may be extended to include other hydrocarbon or mineral oil fractions such as cracked naphthas whose boiling range is sufliciently different from the solvent to permit separation of the carbinol.

In fact the method disclosed herein may be used in connection with the separation of paraffinic and non-paraflinic hydrocarbons in any hydrocarbon mixture containing same.

In the example given covering the use of mixtures of ethynyl carbinols with other selective solvents, it will be noted that the chief, effect of the carbinol is to lower the miscibility temperature. Examples of other solvents which might be used in combination with an acetylenic carbinol are nitrobenzene, aniline, furiural, dialkyl iormamides, phenol, and cresylic acids.

Extraction treatment with ethynyl carbinols or mixtures containing them may be applied to raw distillates or to a partially refined product. Under certain conditions, for example, in the case of oils with high sulfur content or poor sludging characteristics, it may be desirable to supplement the solvent extraction with the usual acid, alkali. doctor, or clay treatment, applied either before or after the extraction.

The advantages of the present invention are:

(1) The production of high grade lubricating oil from mediocre crudes with negligible refining loss compared to the ordinary acid-alkali process.

(2) The increasing of the paraflinic content of a hydrocarbon mixture containing parafiinic and non-parafiinic hydrocarbons by the removal of some of the non-parafllnic hydrocarbons therefrom.

(3) Combinations oi acetylenic carbinols with other selective solvents result in lowering of miscibility temperatures with substantially the same yield and quality of rafilnate, thereby permitting operation of the solvent extraction processes under favorable conditions for heat-susceptible oils.

It is apparent that many widely different embodiments of this invention may be made without departing Irom the spirit and scope thereof, therefore it is not intended that the invention be limited except as defined by the appended claims.

I claim:

arouses l. The method of treating a normally liquid hydrocarbon mixture containing relatively parafiinic and relatively non-paraflinic compounds which comprises extracting the hydrocarbon mixture with a solvent comprising an alcohol having the general formula:

wherein R. and R1 are selected from the group consisting of hydrogen and hydrocarbon radicals, and wherein the total number of carbon atoms in Band R1 is lessthan 'l.

2. process in accordance with claim 1 characterized in that the alcohol is isopropyl ethynyl carbinol.

3. The method of treating a normally liquid hydrocarbon mixture containing relatively paramnic and relatively non-paraflinic compounds so as to separate at least a portion of said relatively non-paraflinic compounds from admixture with said relatively paraflinic compounds which comprises commingiing with said hydrocarbon mixture a solvent comprising an alcohol 0! the eneral formula CEGH wherein R and R1 are selected from the group consisting of hydrogen or hydrocarbon radicals and wherein the total number of carbon atoms in R and R1 is less than "i, causing the resulting mixture to separate into two layers, separating the two layers, and recovering the hydrocarbon traction contained in each layer.

4. The process in accordance with claim 3 characterized in that the ratio of the oil to the extracting solvent is between about 1 to 10 and about 5 to i.

5. The method of treating a normally liquid hydrocarbon mixture containing relatively paraflinic and relatively non-paraflinic compounds so as to separate at least a portion of said relatively non-paraiilnic compounds from admixture with said relatively paraihnic compounds which comprises with said hydrocarbon mixture in approximately equal volume an alcohol having the general formula:

wherein R and R1 are selected from the group consisting of hydrogen and hydrocarbon radicals and wherein the total number of carbon atoms in R. and R1 is less than "I, heating said mixture to a temperature at which the hydrocarbon mixture and alcohol becomes miscible, then cooling said mixture while agitating to at least 20 below the temperature of complete miscibility causing the resulting mixture to separate into two layers, separating the two layers, and recovering the hydrocarbon fraction contained in each layer.

6. The process in accordance with claim 5 characterized in that the alcohol is isopropyl ethynyl carbinol.

'1. The method of treating a normally liquid hydrocarbon mixture containing relatively parailinic and relatively non-parailinic compounds 80 as to separate at least a portion of said relatively non-parafllnic compounds from admixture with said relatively paraflinic compounds which comprises commingling with said hydrocarbon mixture an approximately equal volume of isopropyi ethynyl carbinol at a temperature of about 50 0., then cooling said mixture to about 20 C. while agitating, allowing the resulting mixture to separate into two layers, separating the two layers and recovering the hydrocarbon fraction contained in each layer.

8. The process in accordance with claim 1 characterized in that the alcohol is dimethylethynyi carbine].

9. The process in accordance with claim 1 characterized in that the alcohol is methylethylethynyl carbinol.

10. The process in accordance with claim 5 characterized in that the alcohol is dimethylethynyl carbinol.

11. The process in accordance with claim 5 characterized in that the alcohol is methylethylethynyl carbinol.

HAROLD S. HOLT.

CERTIFICATE OF CORRECTION- Patent no; 2,161,625.

June 6, 1939.

HAROLD S. HOLT;

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows; Page 2, sec- 0nd column, line B, for "ethnyl" read ethynyl; 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 18th day of July, A. D. 1959.

(Seal) Henry Van Arsdale, Acting Commissionerof Patents.