US2354812A - Separation of tall oil into its constituents - Google Patents

Description

Aug. l, 1944.

SEPARATION OF TALL OIL INTO ITS CONSTITUNTS JQ D. JENKINS l Filed Deo. 19, *1941.

TME/311- Patented Aug. 1, 1944 SEPARATION F TALL OIL INTO ITS CONSTITUENTS John D. Jenkins, Milwaukee, Wis., assignor to Pittsburgh County, Pa.,

Plate Glass Company, Allegheny a corporation of Pennsylvania Application December 19, 1941, Serial No. 423,627 2 Claims. (01.260-975) The present invention relates to the separation of tall oil into its components Aand it has particular relation to such separation when effected by means of a system of selective solvents.

One object of the invention is to provide a simple process of obtaining a fraction oi' fatty acids in high concentration from the resin acids in tall oil.

A second object of the invention is to provide a simple and convenient embodiment of apparatus -for use in the practice .of the invention.

These and other objects will be apparent from consideration of the following specification and the appended claims.

Tall oil results from the manufacture of paper pulp by the sulfate method and is obtained in amounts of thousands of tons annually. It comprises a mixture of components including large percentages of fatty acids and resin acids, together with some nonacid constituents, which include considerable amounts of sterols. The latter are highly valuable for use in the preparation of certain pharmaceutical materials.

The fatty acids are of such nature that, in.

suiiiciently pure state, they would be of great value in the preparation of synthetic resins,

soap `stocks and the like. However, by reason of the presence of the resin acids, it has heretofore been impracticable to employ them to any appreciable degree, except in a few very cheap products. Therefore, the value of tall oil has always remained 10W. Y

The present invention contemplates the provision of a process whereby large percentages of free fattyacids can be separated in comparatively pure form from the resin acids while the resin acids in turn are obtained in a comparatively concentrated state.

For a better understanding of the invention reference may now be had to the accompanying drawing in which Figs. l and 2 illustrate lclingrammatically convenient invention.

In the drawing like numerals refer to like parts throughout.

The apparatus as shown includes an extraction column I0, which may be of conventional design and preferably includes a packing or Raschig rings, or other suitable material designed to promote complete and thorough lntermingling of liquids passing through the column. A selective polar solvent having an amnity for resin acids is psd into the top of the column as indicated a embodiments of the- This/solvent may comprisean aqueous Il solution o f the monomethyl ether of ethylene glycol, furfural, or diacetone alcohol or any one of a number of polar solvents, which tend selectively to dissolve resins in tall oil. The concentration of water in the solvent should not be too high. For example, in the case of the monomethyl ether of ethylene glycol it should be within the approximate range of 8 to 12 per cent. In the case of furfural, it probably should be about 2 to 4 per cent. In the case of diacetone alcohol the ratio of water should approximate 1i per cent.

Tall oil to be extracted in the column may be stored inv a container I2 and naphtha or the like hydrocarbon solvent, having a preference for fatty acids and being immiscible with the polar solvent, may be stored in a container I3. 'I'he tall oiLand the 'naphtha are discharged through lines I4 and I6 into a common line I1 where they are intermingled, then 4discharged into the base portion of the column I0 where they flow concurrently to each other and counter-currently to the polar solvent.

A rst raillnate highly rich in fatty acids and containing a considerable proportion of the nonacid constituents all dissolved in the naphtha are discharged at the top of the column as indicated at I8. The first extract comprising the selective polar solvent and the major portion of thev resiny acids, as well as some of the fatty acids, is discharged a's indicated at- I9 from the base of the column. The extract, if desired, may be concentrated by evaporation of solvents in a still 2i. However, this operation is optional and, if preferred, the extract may be passed through line 22 directly to a second column 23, which is fed near its bottom with a second portion of naphtha introduced at 24.

The extract from column 23 comprises a high concentration of resin acids and a considerable percentage of fatty acids. It is withdrawn as indicated at 26 near the base -of the column. The second raffinate, comprising naphtha in which is dissolved an enriched portion of fatty acids and a small amount of resin acids, is drawn oil' at 21, near the top of column 23 and is returned as a back feed to the base of the column Ill. If desired, it may be passed through a still 28, where it is substantially concentrated and then returned to the naphtha feed through a line 29. However, the concentration is not strictly required. If preferred, the complete railinate may be recycled without concentration. Where the second raiilnate is concentrated, the puried or .ployed in 2 partially purmed returned thrmlh the in container Il.

Railinate from column naphtha from the still 2l is line Il to naphtha storage il may be fed optionally .with or without being concentrated in still I3,

to the base of a third column 34. where it is counter-currently washed with a wet polar solvent introdued as indicated at 3 8 at the top. The third raiiinate, highly rich in fatty acids and non-acids, passes out as indicated at 31- near the' top of the column 34 while the extract comprising the wetpolar solvent together with a concentration of resin acids and a portion of fatty acids and non-acidsis drawn oi! as indicated at $8 near the base.

vent.

Column I may be fed at Il with a mixture comprising 8 to 12 per cent of water in monomethyl ether of ethylene glycol. The proportion of solvent mixture may be approximately 4250 parts by weight. Approximately 126 parts by weight of tall oil from container l2 and 379 parts by weight of naphtha or petroleum ether are intermingled and fed to the base of the column at Il. l Approximately 1950 parts by weight of naphtha or petroleum ether are fed to the base of column 23 and approximately 1000 -parts by weight, of wet polar solvent maybe fed in at the top of column 34. The rafllnate from the third extraction will comprise a mixture of resinsand fatty acids in .which the ratio of fatty acidswill be approximately 90 per cent and the resin acids will be approximately 10 per cent, based upon total acids content of the fraction. The extract will comprise fatty acids and resin acids in the approximate ratios of 43 and 5'l per cent.

The extract can be used in certain soap stocks, or otherwise worked up or utilized. The raillnate is valuable for use in resin manufacture and other purposes.

A slightly modified embodiment of apparatus' suitable for use in the practice of the invention is disclosed in Fig. 2; This apparatus includes a column 40 designed to receive a feed of tall oil and naphtha or other suitable hydrocarbon at an intermediate point, e. g., approximately the'middle, as indicated at 4|.: A polar solvent medium,

such as aqueous monomethyl 'ether of ethylene glycol is fed into thesystem at or near the top of the column at the point indicated by the arrow 42. Naphtha for absorbing and carrying away the fatty acids of the tall oil mixture is introduced near the base of the column as i'ndicated at 43. "I'he extract is also drawn off at the base, preferably slightly below the point of in- .5

troduction of the naphtha, as indicated at 44.

The raffinate phase comprising primarily a concentrate of free fatty acids in naphtha passes out through line 41 and is fed into the base portion of a second column ,48 and flows countercurrently upwardly through a second wash of aqueous polar solvent introduced at 49. A second extract is taken off at the base of the second column as indicated at 5l while a second raffinate -15 of polar is taken of! near the top of the column, as indicated at l2.

It will be apparent that the operation of this apparatus is very similar to that disclosed in Fig. 1, where the latter is operated without removal of solvent between stages. The upper portion of the column 40 acts substantially as the column III of Fig. 1 and the lower portion behaves as the column 23 in which the extract phase afrom the top of the column is rewashed with hydrocarbon;

It will be apparent that the extracts from either of the columns and the railinate from the column 4B can be drawn olf for further treatment. For example, the second raffinate from the outlet 52 includes free fatty acids and a relatively high percentage of sterols which can be separated from each other by combination of chemical and extraction steps. For example, the raffinate phase may be distilled to eliminate the solvent medium after which it can be treated with aqueous alkali, such as sodium or potassium hydroxide to saponify the free acids. The sterol: can then be extracted from the acids by means of a suitable solvent, such as ether. The fatty acid after saponiiication can, if desired,'be further treated in order to obtain conjugate and non-conjugate portions therefrom. Such process is disclosed in my copending application Serial No. 423,623, filed December 19, 1941, and entitled Treatment of tall oil.

The process broadly involves hydrolyzation of the soaps followed by este'rification and further extraction with a selective solvent system, such as simultaneous extraction with furfural, or ethyl acetoacetate and petroleum naphtha. Such treatment results in separation of a fraction exceptionally rich in non-conjugate acids, which fraction is well adapted for use as a modifier in alkyd resins. t

The extract phases from outlets 44 and 5l can also be treated for purposes of removing free resin acids from the fatty acids. A convenient process for this purpose is disclosed in my copending application entitled Refining of tall oil, Serial No. 423,626, filed December 19, 1941. It involves the addition of water to the extract phases, in order to bring the water content up to the point at which the resin acids will vtend to crystallize out. In the case of methyl ether of ethylene glycol this is conveniently effected when the solvent medium contains about 24 per cent of water. The resin acids then crystallize out and can be recovered. Of course, if desired, the removal of the resin acids by crystallization can be stopped at a con-- venient point, for example, when the concentration of the resin acids to fatty acids is approximately the same as that in the original tall oil. The crystals can be removed from this solution,

the solvent evaporated andthe tall oil recycled to column 40 along with additional tall oil. The various phases from the outlets 5l and 52 can also be separated from the solvents, for example, by a vacuum evaporation and are then suitable for industrial applications. Forexample, the resin action fraction can be employed as a stock for certain soaps, while the fatty acids can be used as modifiers for artificial resins, soap stocks and other industrial applications.

The-preliminary admixture of the tall oil with the tall oil fed into the extraction columns with naphtha has been described. It will be apparent that'it could also be admixed with the initial feed solvent. For example tall oil admixed with wet solvent could be fed into columns I or 4l through lines Il and 42.

'I'he forms of the invention herein shown andV described are to be considered merely as exemplary. It will be apparent to those skilled in the art that numerous modifications can be made therein Without departure from the spirit of the invention or the scope of the claims.

What I claim is:

1. A process of separating tall oil into useful fractions. one being substantially enriched in resin acids andcorrespondingly impoverished in fatty acids and the other beingsubstantially enriched in`fatty acids and impoverished in resin acids, which process comprises admixing tall oil with a liquid hydrocarbon solvent, flowing it through a first zone countercurrentiy to and in contact with a mixture of water and a water miscible polar solvent which has a relatively high aiiinity for the resin acids and a'. lesser aiiinity for fatty acids and is insoluble in the hydrocarbon solvent and simultaneously subjecting'the extract I phase from the first zone to countercurrent washing in a second zone with a liquid hydrocarbon solvent having va relatively high aflinity for fatty acids, the polar -solvent exceeding the hydrocar- -bon in volume, flowing the hydrocarbon solvent used in said washing operation through the first zone, withdrawing a phase comprising the hydrocarbon solvent and the acids dissolved therein from the first zone and further extracting the last mentioned phase with additional polar solvent in a third zone to obtain two additional phases, one comprising hydrocarbon saturated ished in resin acids and the other comprising the polar solvent saturated with a fraction rich in resin acids and poor in fatty acids. y

2. A process of separating tall oil into useful fractions, one being substantially enriched in resin acids and correspondingly impoverished in fatty acids and the other being substantially enriched in fatty acids and impoverished in resin acids, which process comprises admixing tall oil in a ratio of about ,-126 parts by weight with a liquid hydrocarbon solvent through a ratio of about 379 parts by weight, flowing it in a first zone countercurrently to a mixture of monomethyl ether of ethylene glyco1 and water in a ratio of about 4250 parts by weight and simultaneously subjecting the extract from the first zone to countercurrent washing in a second zone with a liquid hydrocarbon solvent in a ratio of about 1950 parts by weight having a relatively high aflinity for fatty vacids and lesser ainity for resin acids, flowing the hydrocarbon solvent used in said washing operation through the first zone, withdrawing a phase comprising the hydrocarbon solvent and the acids dissolved therein fromthe first zone and further extracting the solution with additionalv monomethyl ether of ethylene glycol in a third zone to obtain twoiadditional phases, one comprising hydrocarbon saturated with said fraction of fatty acids impoverished -in resin acids and theother comprising the monomethyl ether of l ethylene glycol saturated with a fraction rich in resin acids and poor in fatty acids.

JOHN D. JENKINS.

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