US2265020A - Process for refining fatty acids - Google Patents

Description

i Patented Dec. 2, 1941 2,265,020 PROCESS FOR REFINING FATTY ACIDS Ralph M. Beach, Newark, and Edwin A. Robinson, Chatham, N. J., assignors to National Oil Products Company, Harrison, N. 1., a corporation of New Jersey No Drawing. Application March 31, 1939, Serial No. 265,134

6 Claims.

This invention relates to the refining of crude fatty acid compositions.

Crude fatty acid compositions such as are obtained by the saponification of vegetable or fish oils are ordinarily dark-colored and illsmelling due to the presence of considerable amounts of odoriferous and coloring materials, and hence are somewhat unsuitable for use in soap making and the like, since the odor and color tend to remain in the products prepared therefrom and thus render these products unacceptable for a great many purposes. These crude fatty acid compositions are ordinarily deodorized and decolorized by distilling the compositions and recovering purified fatty acids in the distillate; however, this method of operation is relatively expensive, requires special 'equipment and causes the destruction and consequent loss of a considerable portion of the fatty acids.

A method for deodorizing and decolorizing tall oil, a dark-colored and ill-smelling composition comprising approximately equal amounts of rosin and fatty acids and also containing unsaponifiable matter, is described on pages 33 and 34 of the Paper Trade Journal of October 1, 1936; the method involves dissolving tall oil in gasoline and agitating the tall oil solution with furfural, whereby a large part of the odoriferous and coloring materials in the tall 011 dissolves in the furfural and is removed. This article states the gasoline insoluble constituents of crude tall oil, i. e., constituents extracted by furfural, are responsible for the undesirable color and odor of the oil, and that these constituents originate practically entirely from the rosin contained in the tall oil. This article, therefore, provides a process for removing undesirable products of a rosin origin from compositions containing rosin and fatty acids; however, the problem of removing odoriferous and coloring material from crude fatty acid compositions containing substantially no rosin by a method more advantageous than the distillation method remains unsolved.

It is the object of this invention to provide a simple and inexpensive process for the refining of crude fatty acid compositions containing substantially no rosin.

We have now discovered fatty acid compositions having a light color and substantially free fromeobjectionable odors may be prepared from crude fatty acid compositions having objectionable color and odor and containing substantially no rosin by contacting a solution of the crude fatty acid composition with an organic solvent substantially immiscible with the fatty acid solution and having a radical selected from the group consisting of 0 0H and JL-x wherein X represents a substituent selected from the group consisting of H, OH and organic radicals having a carbon atom at the end adjacent the carbonyl group. The organic solvent, after contact with the crude fatty acid solution, separates therefrom and forms a layer in which-is contained substantially all the odoriferous and coloring materials present in the crude fatty acid composition. This layer is withdrawn and the refined fatty acids may then be recovered, whereby a fatty acid composition is obtained which has a pale yellow to light brown color, as compared to the dark brown or black color of the original material, and is substantially free of undesirable odors.

I The organic solvent used in accordance with our invention to remove the odoriferous and coloring materials from the crude fatty acid composition may be any organic solvent substantially immiscible with the crude fatty acid solution with which it is contacted and having a radical selected from the group consisting of wherein X represents H, OH or an organic radical having a carbon atom at the end adjacent the carbonyl group. We have found th following solvents to'be-particularly suitable for the practice of our invention: furfural, methyl furfural, ethylene glycol, diethylene glycol mono ethyl ether, ethylene chlorhydrin, tetrahydrofurfuryl alcohol, glacial acetic acid and acetone. It is to be understood, however, other solvents having the above characteristics may be used.

The crude fatty acid compositions which may be refined in accordance with our invention include any of the vegetable or fish fatty acids, as well as fatty oils comprising predominantly free fatty acids and containing a minor amount of triglycerides, and fatty acid esters obtained by esterifylng such acids or fatty oils. Thus, for example, fish fatty acids, such as cod oil fatty acids, sardine oil fatty acids, sperm oil fatty sulfuric acid and steaming, and vegetable fatty acids such as cotton seed fatty acids, linseed fatty acids, soya bean fatty acids, corn oil fatty acids, coconut oil fatty acids, 'etc., may be treated. It is also intended to include naphthenic acids within the scope of the term "fatty acids, since these acids, while not strictly fatty acids, possess practically all the properties of fatty acids and may be treated in substantially the same manner in accordance with this invention.

In carrying out the process of our invention a crude fatty acid composition containing substantially no rosin and comprising predominantly free fatty acids, preferably at least about 90% free fatty acids, is dissolved in a suitable solvent. The particular solvent employed depends to some extent upon the organic solvent to be used to extract the odoriferou and coloring materials; thus, for example, acetone is miscible with a solution of crude fatty acids in heptane, but effects a suitable separation of the odoriferous and coloring materials when it is contacted with a crude fatty acid composition dissolved in cyclohexane. Generally, however, any organic solvent capable of dissolving crude fatty acids may be used. such as, for example, gasoline, heptane, cyclohexane or decahydfonaphthalene. The amount of solvent used to dissolve the crude fatty acid composition may vary somewhat depending upon the particular solvent employed; between about 60 andabout 100 parts of solvent for every 10 parts of the crude fatty acid is ordinarily suitable. The crude fatty acid solution thus produced is preferably subjected to a bleaching treatment prior to contact with the organic solvent used to extract the odoriferous and coloring materials, since we have found the color of the fatty acid product is materially improved thereby. The bleaching treatment may be accomplished in any desirable manner, such as, for example, by forming an alkali solution of the fatty acid soaps and passing chlorine therethrough, or by treating the fatty acid solution with sulfur dioxide or hydrogen peroxide. The crude fatty acid solution may also be treated, prior to its extraction, with bisulfites to remove aldehydic and ketonic materials which may be present.

The fatty acid solution obtained as above described may then be contacted with an appropriate amount of an organic solvent having the characteristics set forth hereinabove. The amount of the organic solvent used may vary depending upon the particular solvent employed and the nature of the solvent used to dissolve the fatty acid composition. We have found between about V2 and about 3 parts of organic solvent per part of crude fatty acid composition present in the solution is suitable. More effective removal of the odoriferous and coloring materials from the crude fatty acid solution may be accomplished by contacting the solution with successive batches of the organic solvent; thus the solution may be contacted with two or three or even more batches of organic solvent. The contact of the fatty acid solution with the organic solvent may be effected in any suitable manner, e. g., by agitation or countercurrent flow. The total time of contact of the organic solvent with the crude fatty acid solution should be sumcient to extract substantially all the odoriferous and coloring materials from the fatty acid solution; generally, between about 5 and about minutes is suitable. The temperature of the extraction may be any desirable temperature, e. g., room temperature; however, it may sometimes-be advantageous to carry out the extraction at somefiltered to remove insoluble material.

what elevated temperatures, e. g., about 60 C., in order to increase the mutual solubilities of the liquids and thus effect a more complete extraction.

When the organic solvent has been contacted with the fatty acid solution for a sufficient time, the mixture may be permitted to separate into two layers; if the contact has been carried out at elevated temperatures, the mixture is preferably cooled to between about 15 and about 20 C. before the layers are permitted to separate. The upper layer comprising the purified fatty acid solution is withdrawn and the refined fatty acids may be recovered therefrom in any suitable manner, e, g., by distillation. In some cases it may be desirable to utilize the solution of refined fatty acids directly, in which event, it is not necessary to remove the solvent. The lower layer containing the organic solvent and substantially all the odoriferous and coloring materials contained in the crude'fatty acids is also withdrawn, and the organic solvent may be recovered therefrom. If the organic solvent thus recovered possesses any undesirable odor which would render it unfit for reuse, the odor may be removed in any appropriate manner, e. g., by blowing hot-air therethrough. The odoriferous and coloring materials which remain as residue after recovery of the organic solvent may be discarded or used as desired.

If desired, the refined fatty acids may be treated with bleaching earths, e. g., fullers earth, activated bentonite, etc., or activated carbon to further decolorize and deodorize the product. However, in most cases this treatment is entirely unnecessary, since the fatty acids produced in accordance with our invention are of sufflcient purity to permit their use without further treatment.

The following examples are illustrative of our invention. Amounts are given in parts by volume.

Example I 10 parts of crude cod oil fatty acids were dissolved ln parts of heptane. The solution was permitted to stand for about one hour and then The filtrate was then extracted with 30 parts of furfural in successive batches of about 10 parts each by mixing the solution with each batch of furfural. warming the mixture to about 60 C., agitating for about 3 minutes, cooling to between about 15 and 20 C., and permitting the mixture to separate into two layers, the top layer comprising the solution of the refined fatty acids, and the bottom layer comprising a solution of the odoriferous and coloring materials in furfural. After the last extraction, the refined fatty acid solution was shaken with a small amount of fullers earth, and the solvent then removed by distillation. The refined fatty acids thus obtained gave a Lovibond reading of 2.6 red and 22 yellow; the crude fatty acids were much too dark in color to obtain any Lov'lbond reading. Furthermore, the refined product possessed no undesirable odor. Furfural was recovered by evaporation thereof from the solutions containing odoriferous and coloring materials.

Example II 10 parts of menhaden fatty acids which had been treated with sulfuric acid and hydrolyzed by steaming were dissolved in parts of heptane. The solution was then mixed with 20 parts of methyl furfural and the mixture agitated for about minutes. At the end of this time, the mixture'was permitted to separate into two layers, the lower layer containing the methyl furfural and the odoriferous and coloring materials mthdrawn, and refined fatty acids recovered from the upper layer by evaporating the solvent. The refined product gave a Lovibond reading of 5.6 red and 25 yellow; the crude fatty acids were .much too dark'ito give any Lovibond reading. Furthermore, the refined product possessed no undesirable color. Methyl furfural was recovered by evaporation thereof from the solution containing odorlferous and coloring materials,

' Example III 10 parts of linseed oil fatty acids having a bad odor and a dark brown color were dissolved in 60 parts of petroleum ether. The solution was then agitated with ,5 parts of furfural for about 10 minutes. At the end of this time, the mixture was permitted to separate into two layers, the lower layer containing furfural and the odoriferous and coloring materials withdrawn, and refined fatty acids recovered from the upper layer by evaporating the petroleum ether. The refined product had a light amber color and possessed no undesirable odor. Furfural was recovered by evaporation thereof from the solution containing odoriferous and coloring materials.

. Example IV 10 parts of a mixture of naphthenic acids having a dark brown color and an undesirable odor were dissolved in 70 parts of gasoline. The solution was then agitated with 30 parts of methyl furfur'al for about 10 minutes. At the end of this time, the mixture was permitted to separate into two layers, the lower layer containing methyl furfural and the odorlferous and coloring materials withdrawn, and refined naphthenic acids recovered from the upper layer by evaporating the gasoline. The mixture of refined naphthenic acids thus obtained had a light brown color and possessed no undesirable odor. Methyl furfural was recovered by evaporation thereof from the solution of odorlferous and coloring materials.

Example V 10 parts of cod oil fatty acids having a dark brown color and an undesirable odor were dissolved in 80 parts of heptane. The solution was then agitated with 10 parts of tetrahydrofurfuryl alcohol for about 10 minutes. At the end of this time, the mixture was permitted to separate into two layers, the lower layer containing the tetrahydrofurfuryl alcohol and the odorlferous and coloring materials withdrawn, and refined fatty acids recovered from the upper layer by evaporating the heptane. The refined fatty acids thus obtained had a pale amber color and possessed no undesirable odor. Tetrahydrofurfuryl alcohol was recovered by evaporation thereof from the solution of ordoriferous and coloring materials.

Example VI At the end of this time, the

refined fatty acids thus obtained had a pale amber color and possessed no undesirable odor. Ethylene glycol was recovered by evaporation thereof from the solution of odoriferous and coloring materials.

Example VII 10 parts of cod oil fatty acids having a dark brown color and an undesirable odor were, dissolved in 80 parts of heptane. The solution was then agitated with 10 parts of diethylene glycol monoethyl ether for about 10 minutes. At the end of this time, the mixture was permitted to separate into two layers, the lower layer containing the glycol .ether and the odorlferous and coloring materials withdrawn, and refined fatty acids recovered from the upper layer by evaporating the heptane. The refined fatty acids thus obtained had a pale amber color and possessed no undesirable odor. The glycol ether was recovered by evaporation thereof from the solution of odorlferous and coloring materials.

Example VIII 10 parts of cod oil fatty acids having a dark brown color and an undesirable odor were dissolved in 80 parts of cyclohexane. The solution was then agitated with 10 parts of glacial acetic acid for about '10 minutes. At the end of this time, the mixture was permitted to separate into two layers, the lower layer containing acetic acid and the odorlferous and coloring materials withdrawn, and refined fatty acids recovered from the upper layer by evaporating the cyclohexane. The refined fatty acids thus obtained had a pale amber color and possessed no undesirable odor. Acetic acid was recovered by evaporation thereof from the solution of odorlferous and coloring materials.

Example IX 10 parts of cod oil fatty acids having a dark brown color and an undesirable odor were dissolved in 80 parts of cyclohexane. The solution was then agitated with 10 parts of ethylene chlorhydrin for about 10 minutes. At the end of this time, the mixture was permitted to separate into two layers, the lower layer containing the chlorhydrin and the odorlferous and coloring materials withdrawn, and refined fatty acids recovered from the upper layer by evaporating the cyclohexane. The refined fatty acids thus obtained had a pale amber color and possessed no undesirable odor. Ethylene chlorhydrin was recovered by evaporation thereof from the solution of odorlferous and coloring materials.

Example X 10 parts of cod oil fatty acids having a dark brown color and an undesirable odor were dissolved in parts of cyclohexane. The solution was then agitated with 10 parts of acetone for about 10 minutes. At the end of this time, the mixture was permitted to separate into two layers, the lower layer containing the acetone and the odorlferous and coloring materials withdrawn, and refined fatty acids recovered from the upper layer by evaporating the cyclohexane. The refined fatty acids thus obtained had a pale amber color and possessed no undesirable odor. Acetone was recovered by evaporation thereof from the solution of odorlferous and coloring materials.

It will be evident from the above description that our invention provides a simple and inexpensive process for recovering fatty acids of light color and pleasant odor from crude fatty acids of extremely dark color and having disagreeable odors. The practice of the process requires no special equipment and may be carried out with very little loss of fatty acid product. Our invention, therefore, will'be of value to all industries employing refined fatty acids, particularly industries such as those engaged in the manufacture of soaps, textile lubricants, wetting agents, leather oils and the like. V

Since certain changes may be made in carrying out the above process without departing from the scope of the invention, it is intended that all matter contained in the-above description shall be interpreted as illustrative and not in a limiting sense.

Having described our invention, what we claim as new and desire to secure by Letters Patent is:

1. A process of decolorizing and deodorizing rosin-free crude fatty acid compositions having a, free fatty acid content of at least 90% which comprises contacting a normally liquid hydrocarbon solvent solution of such a rosin-free crude fatty acid composition with an odor and color extracting solvent selected from the group consisting of furfural, methyl furfural, ethylene glycol, diethylene glycol monoethyl ether, ethylene chlorhydrin, tetrahydrofurfuryl alcohol, glacial acetic acid and acetone and separating the hydrocarbon solvent solution of the decoiorized and deodorized fatty acids from the extracting solvent solution of the coloring and odoriferous bodies.

2. A process of decolorizing and deodorizing rosin-free crude fatty acid compositions having a free fatty acid content of at least 90% which comprises agitating one part of a normally liquid hydrocarbon solvent solution of such a rosin-free fatty acid composition with between one-half and three parts of an odor and color extracting solvent selected from the group consisting of furfural, methyl furfural, ethylene glycol, diethylene glycol monoethyl ether, ethylene chlorhydrin, tetrahydrofurfuryl alcohol, glacial acetic acid and acetone, permitting the mass to settle. whereby the extracting solvent containing the coloring and odoriferous bodies separates in a distinct layer from the hydrocarbon solvent solution of the decolorized and deodorized fatty acids and separating the aforementioned layers. 3. A process of decolorizing and deodorizing rosin-free crude fatty acid compositions having a free fatty acid content of at least which comprises dissolving such a rosin-free crude fatty acid-composition in a normally liquid hydrocarbon solvent therefor, subjecting the solution to a bleaching treatment, agitating the bleached solution with a color and odor extracting solvent selected from the group consisting of furfural, methyl furfural, ethylene glycol, diethylene glycol monoethyl ether, ethylene chlorhydrin, tetrahydrofurfuryl alcohol, glacial acetic acid and acetone and separating the hydrocarhon solvent solution of the .decolorized and deodorized fatty acids from the extracting solvent" solution of the coloring and odoriferous bodies.

4. The "process as set forth in claim 1 wherein the extracting solvent used is furfural.

5. The process as set forth in claim 1 wherein the extracting solvent used is methyl furfural.

6. The process as set forth in claim 1 wherein the extracting solvent used is diethylene glycol monoethyl ether.

RALPH M. BEACH. EDWIN A. ROBINSON.