US2573896A - Treatment of glyceride oils - Google Patents

Description

Nov. 6, 1951 s. E. FREEMAN TREATMENT oF GLYCERTDE oTLs Filed Aug. l, 1945 Patented Nov. 6, 1951 TREATMENT OF GLYCERIDE OILS Stephen E. Freeman, Pittsburgh, Pa., assigner to Pittsburgh Plate Glass Company, Allegheny County, Pa., a corporation ol' Pennsylvania Application August 1, 1945, Serial No. 608,119

Claims. (Cl. 26o-428.5)

The present invention relates to the treatment of glyceride oils by solvent extraction and it has particular relation to the treatment of natural glyceride oils comprising mixtures of glycerides of fatty acids of varying degrees of unsaturatlon, free fatty acids from the glycerides, tocopherols, sterols, inhibitols, vitamins, break constituents, such as phospholipids, lecithin, gums, and the like in order to refine them and to separate out the constituents in a manner admitting of their more satisfactory application in the arts.

The objects of the invention comprise:

Firstly, to provide a process whereby oils including mixtures of the foregoing constituents may be refined in order to free all or a portion of the glyceride components of the acids. the break constituents, inhibitol's, or the like which may be obj ectionable therein;

Secondly, to provide a process as specified above in which the oil is also fractionated into a relatively highly unsaturated portion and a relatively highly saturated portion; Y

Thirdly, to obtain a concentrate of free fatty acids and unsaponiables such as sterols, lnhibitols, tocopherols, and vitamins which with or without further fractionation and processing is of great value as a source of pharmaceuticals, soap constituents, resin constituents and other valuable products;

Fourthly, to provide a process of refining glyceride oils to obtain an oil product which is free of break, gum, free fatty acids, and other constituents which are objectional in the glycerides as normally employed, in which process the losses accompanying refining are reduced to a minimum.

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

It has heretofore been recognized that natural glyceride oils such as soya bean oil, linseed oil, cottonseed oil, menhaden oil, iish liver oils and the like include as their main constituent glycerides of the higher fatty acids, but that they also include free fatty acids, break constituents, sterols, inhibitols, tocopherols, vitamins, and many other constituents. In most cases, since all of the constituents except the glycerides occur in relatively small amounts, they, heretofore, have either been disregarded or have been eliminated by radical chemical treatment which results in their destruction or their degradation.

It is to be recognized that the glycerides constituting the main component of a conventional glyceride oil usually comprises a complex mixture of the glycerides of a number of fatty acids which diii'er among themselves primarily by reason of diierences in the degree of unsaturation of the hydrocarbon nuclei of the acids. There is much variation in the ratio of unsaturated acids and the degree of unsaturation of the acids which are combined with glycerol to provide the glycerides. Oils, such as linseed oil, tung oil and the like, which are employed in the manufacture of paints and varnishes contain a very high proportion of unsaturated glycerides while most of the food and soap oils, such as coconut oil, cottonseed oil, lard and the like, contain only a small proportion of highly unsaturated glycerides so that they have little or no capacity for drying to form hard protective lms. Certain other oils, such as soya bean oil and the like, are of intermediate character, containing considerable proportions of both types of glycerides. They have, heretofore, been conventionally employed in foods but they are alsosusceptible of use in paints and varnishes.

In my prior Patents Nos. 2,200,390 or 2,200,391, is disclosed, among others, a process for the fractionation of various oils upon the basis of unsaturation of the glycerides whereby there is obtained a concentration of the unsaturates in one fraction and the concentration of the more saturated components especially useful for food purposes in a second fraction. This eifect is obtained by suitably extracting the oil with a polar solvent in appropriate ratio and at a suitable temperature in order partially to dissolve the oil in the polar solvent. The more highly unsaturated glycerides dissolve more readily in these polar solvents than do the highly saturated glycerides -so that the two types of glycerides can thus be fractionated from each other.

The presentinvention contemplates the provision of a process of extracting glyceride oils (preferably natural unrefined unpolymerized glyceride oils) comprising mixtures of glycerides of varying degrees of unsaturation, free fatty acids, sterols, tocopherols, inhibitols, break constituents, vitamins and many other nonsaponifiable ingredients in order to obtain therefrom concentrates of the various components in undamaged condition and relatively free of other components which may be objectionable therein. For example, there is obtained a first railinate of low solubility in furfural. This fraction will vary in amount .dependent upon the oil treated and the subsequent uses contemplated for the fractions. It may be small so as to comprise a concentrate of the break components that can be further treated economically and with little loss of oil. The glycerides in the raffinate are of higher saturation than the original oil. Secondly, there is obtained a dissolved extract containing a small amount of break and a concentrate of the more unsaturated glycerides, the fatty acids, vitamin A or other oil soluble vitamins (if present) and soluble unsaponiii-ables. The extract solution is then extracted with parailinlc naphtha to leave in the polar solvent a fraction low in glyceride content and high in free fatty acids and unsaponiables such as sterols, tocopherols, inhibitols and the like, as well as the furfural soluble break" constituents and to obtain a refined fraction of more highly unsaturated glycerides from the paralnic naphtha solution.

The treatment of the whole oil in order to obtain fractionation as well as a separation of the glycerides from the minor constituents, and to obtain a concentrate of fatty acids and unsaponiiiable constituents as above described may be eifected in accordance with the provisions of the present invention by means of a two column or a three column system in the iirst of which the whole oil is rst extracted, preferably, countercurrently with a selective polar solvent in accordance with the provisions of my prior patents above referred to. Solvents such as furfural, acetonyl acetone, methyl cellosolve, ethyl aceto acetate, mixtures of nitromethane and nitroethane and other polar solvents mentioned in my prior Patents Nos. 2,200,390 or 2,200,391 and which are also immiscible with naphtha may be used. Extraction with furfural is especially meritorious. When the oil is so treated in the rst column, two liquid phases are obtained, one comprising a concentrate of the more highly saturated glycerides and break saturated with some solvent and the other comprising the solvent saturated with the more highly unsaturated glycerides and also containing dissolved therein a concentrate of the vitamins A and D (if present), the coloring matter, unsaponifiables such as sterols, inhibitols, tocopherols, and the like together with the free fatty acids. In accordance with this invention this latter phase is extracted in a second column with a liquid phase paralnic hydrocarbon such as naphtha whereby to remove nearbr all of the glyceride oils of the extracted phase from the first column together with the maior portion of the vitamins A and D (if present) as a naphtha extract and to leave in solution in the solvent a small amount of unsaturated glycerides (generally not more than 3% and usually 1% or less on the basis of total oil), coloring matter, unsaponiables such as vitamin E, inhibitols, sterols, free fatty acids and taste and odor constituents. The latter solution can then be treated by distillation or otherwise to remove the solvents to obtain a concentrate of the foregoing ingredients, the concentrate can further be treated chemically or physically in order to separate the various constituents for use in food and drug products or for other purposes to which the particular constituents of the fraction may be especially adapted.

Assuming that furfural is employed as the selective solvent in the first column of the system. furfural (saturated with naphtha) in a ratio of about 3 to 15 parts per part of oil is fed into the top of the flrst column and the crude or degummed oil usually plus ,to 25% naphtha is fed in near the middle of the column and an extracted oil or a naphtha reflux or a combination of extracted oil and naphtha reflux is fed in near the bottom of the same column. The raffinate solution from this column contains most of the break concentrated in it. This railinate dures.

The extract solution from the first column is pumped directly into the top of the second column and the naphtha in a range of from 1 to 10 parts per part of oil is pumped into the bottom of the column in such amounts as to remove most of the glyceride leaving only a concentrate of the coloring matter, free fatty acids and the unsaponifiable matter in the furfural. The naphtha solution of glyceride oils coming from the top of the second column is of a light color, break free and of low acid value. The naphtha can be eliminated by evaporation. The naphtha extract from the second column can be rewashed with furfural in a third column in order further to reduce the free fatty acids. This stage is optional. This product is comparable to an extract produced from an alkali refined, break free feed oil.

The by-product remaining in the furfural is a concentrate of the coloring matter, free fatty acids and unsaponiflable matter. The unsaponifiable matter includes sterols. antioxidants, inhibitols, tocopherols, natural pigments and other unidentified compounds. This by-product is a good source of raw material for the various unsaponiable constituents by virtue of their increased concentration as compared with the original oil.

The following are some of the results accomplished: Firstly, there is obtained a concentrate of lecithin, phosphatides and other break material in the raiiinate; Secondly, there is obtained a break free varnish or edible oil in accordance with the nature and purpose of the original oil without the use of conventional chemical refining; Thirdly, there is a concentration of the unsaponifiable matter, free fatty acids and coloring matter in a by-product amounting generally to 0.5% to 3% of the original oil.

Apparatus suitable for use in the practice of the invention is illustrated diagrammatically in the single figure of the drawing. The apparatus includes columns I, II, and III, the rst of which is operated with a selective polar solvent in order to fractionate the oil upon the basis of the degree of unsaturation. Oil. such as soya bean oil. linseed oil, fish liver oil. cottonseed oil or the like is stored in a container l0 and may be diluted with naphtha in an amount, say of 10 to 20% fed into the oil from container Il by means of a feed line I2. The oil or the oilnaphtha mixture is fed into the middle portion of column I by means of a feed line I3 at such rate as can conveniently pass through the column with phase separatlon. A reflux of naphtha. optionally, may also be supplied to the bottom of the column by means of feed line Il from the container Il. The flow of liquids through the various feed lines I2, Il and I4 is regulated by means of suitable valves I6 and I1 of conventional design.

Selective polar solvent such as furfural which is relatively immiscible with the naphtha and is but partially miscible with the oil at the temperature of operation is supplied at or near the top of column I by means of a feed line i8 connected to a suitable source (not shown) of supply. The raffinate phase comprising the more highly saturated glycerides together with the major portion of the break constituents of the oil (if they are present) passes out at or near the top of the column and is passed through line I9 to a still 2| for vacuum distillation of the solvents dissolved therein. The solvent free ralnate oil passes out through line 22 to storage or for further treatment. If desired the raflinate may be sent to a fourth column (not shown) and refractionated in a manner similar to that described above. The solvent is drawn off through line 23.

The per cent of. the feed oil in the rafilnate may vary, but usually will be within a range of to 80% dependent upon the character of the oil treated and the product desired. If it drops too low, some portion of the break may tend to remain in the extract. The per cent of raffinate can be controlled by varying the solvent ratio, the temperature, the amount of naphtha in the feed oil or the amount of naphtha or oil reflux feed.

The extract solution comprising as its main constituents most of the solvent saturated with the more highly unsaturated glycerides passes out through line 24 or near the bottom of the column and optionally may pass in its entirety through line 25 directly to the top of column II or a portion may pass to a still 26 Where some or all of the solvent is stripped olf and returned through a line 21 for re-use in the system. The partially or completely stripped oil is drawn off through line 28 and may all pass (along with some oil and solvent bypassed through line 25) thro'gh line 29 to the top of column II. However, usually it is preferable to return a portion, e. g. 10-90% of the extract oil as a reflux through line 3| to the lower portion of the column I. Line 25 between line 24 and line 29 provides a by-pass for the still 26. Conventional valves 33 in the lines 24, 25, 29 and 3| permit the control of the flow of the extract phase in such manner as to by-pass any desired portion of the oil about still 26 or to enable the stripping and refluxing of any desired portion. A convenient mode of operation is to evaporate the extract solution to such a degree that approximately 1/2 to 3A of the furfural is removed before the solution is fed to column II.

A naphtha wash generally within a range of 1 to 10 parts per part of original oil is fed from container 34 to the lower portion of the column II by means of a feed line 36 in order countercurrently to wash the extract oil from column I. In this column the naphtha containing most of the extract oil from column I passes out through line 31 at the top of column II. This fraction may be passed in its entirety to a still 38 for the removal of the solvent, the refined, highly unsaturated glyceride oil passing off through line 42 to storage and the solvent being removed through line 60 for reuse in the system, or, if preferred, a portion of the oil containing naphtha may be returned as a reflux through an optional line 39 to the lowerl portion of column I. If desired, the ratio of naphtha to oil in such reflux may be reduced by passing the reflux through a suitable still 4| connected in the line. Naphtha comprises any hydrocarbon or mixture of hydrocarbons which is immiscible with furfural or the polar solvent being used, and usually comprises a mixture of heptanes, octanes, nonanes and decanes.

The refined oil comprising the more highly unsaturated components of the original oil together with most of the vitamin A or other oil soluble vitamins (if present) of the original oil is obtained through line 42 from the still 38.

6 The extract from column II comprising the polar solvent having dissolved therein, most of the free fatty acids, small amounts of unsaturated glyceridesl coloring matter, unsaponiflables and the like pass out through line 43 to a suitable stripping device such as a still 44 where the solvent may be removed. The extract from the still passes off at 46 to storage or for further treatment in order to fractionate out the various components. The solvent from the distillation may be returned from the still through line 41 for re-use or for storage as may be desired.

In some instances it may be desirable to wash the naphtha solution of oil passing out through line 31 from column II with additional polar solvent such as furfural. This wash may be of low volume, e. g. 1 to 1 on the basis of the oil fraction and is designed to reduce the free fatty acid content. This may be accomplished in column III into the bottom portion of which it is discharged by feed line 4B branching from line 31. Valves 49 control the flow of naphtha and oil to column III and still 38. Furfural or other polar solvent immiscible with naphtha is fed into the top of the column by line 5|, and the extract of solvent and acids or other furfural soluble impurities from the naphtha-glyceride solution passes off through the line 52. The naphtha and the glycerides, *together with vitamin A or other oil soluble vitamins (if present) pass off through line 53. Of course, the solutions from column III can be vacuum distilled to eliminate the solvents. thus providing a refined oil fraction, free of or low in break, color, odor, inhibitols, free fatty acids and the like. The polar solvent extract from column III is a concentrate of all the latter constituents remaining in the polar solvent.

The following tables contain the operating conditions and product data for extracting and refining cottonseed oil, soya bean oil, and linseed oil in a system such as that above described. In these runs, column I was operated with naphtha saturated furfural, column II was operated with naphtha to extract the glycerides from the furfural extract of column II, and column III was operated with naphtha saturated furfural as an extra wash for the naphtha solution from column II.

RUN NO. l-COTIONSEED OIL OPERATING CONDITIONS Column temperatures Column feeds Oil feed to column I, no naphtha Furfural feed to column I, 3 to 1 based on oil feed rate Reflux feed to column I, none Naphtha feed to column II, 1 to 1 based on oil feed rate OPERATING CONDITIONS Column temperatures F. I 113-115 n 53- 5v Column feeds Oil feed to column I, 12% by weight naphtha Furfural feed to column I, 8 to 1 based on oil feed rate Oil reflux to column I, 1.1 to 1 based on oil feed rate Naphtha reux to column I, none Naphtha feed to column II, to 1 based on oil feed rate Column feeds Oil feed to column I, 12% by weight naphtha Furfural feed to column I, 6 to l. based on oil feed rate Oil redux column I, .67 to l based on oil feed rate Naphtha reux to column I, none Naphtha feed to column II, 4 to l based on oil feed rate Product data Original .By- Product on Extract Railinate Product 'laken from line 37 19 43 Yield per cent.- 59 38. 4 2.6 Iodine Value 172 196. 6 146. 5 172.8 Acid Value 2. 33 3 l. 2 39. 0

In these three runs the extract solution from column I was pumped directly to the top of co1- umn II with no intermediate distillation.

The process described may be operated primarily for refining crude or raw oil by taking out break constituents such as phosphatides and lecithin in a glyceride ramnate from column I and refined extract oil in a naphtha wash from column 1I. In such process it is desirable to make the rafnate of column I as small as possible consistent with adequate separation of the break from the furfural extract. It is also possible to so operate as to obtain a refined extract of substantially increased iodine value dissolved in naphtha from column II. In either event, a solution of fatty acids, inhibitols, tocopherols, and sterols together with a little glyceride oil is obtained in the by-product from column II. This concentration, as previously stated, is eminently suitable for further treatment to obtain the free fatty acids, inhibitols, tocopherols, yand sterols as partially or completely l separated components. A convenient process of so treating the by-product comprises distilllng the furfural saponifying the free acids with alcoholic sodium or potassium hydroxide, then distilllng off the alcohol. The soaps can be dissolved in water and the sterols, inhibitols, tocopherols, and other unsaponiable constituents dissolved out in petroleum naphtha or other suitable solvent. The sterols can be crystallized from the naphtha.

Other well-known methods which may be used for further concentrating and recovering the unsaponifiable matter from the by-product might include: (l) Twitchellizing the stock to form fatty acids, distilling the fatty acids and recovering the unsaponiflable matter from the still bottoms in the conventional manner described above; or, (2) preparing esters of the fatty acids present in the by-product with monohydric alcohols such as methyl alcohol by a process of alcoholysis or any other conventional method, distilling the methyl esters and recovering the unsaponiiiable matter from the still bottoms in the conventional method described above.

The forms of the invention herein disclosed are to be regarded as merely constituting examples illustrating broad principles of operation. Numerous modifications can be made therein without departing from the spirit of the invention or the scope of the claims.

Iclaim:

- 1. A method of treating glyceride oil containing glycerides of different' degrees of unsaturation which comprises extracting the oil with furfural to provide a liquid furfural solution which contains unsaturated glycerides and a second liquid phase which contains relatively more saturated glycerides, separating the liquid furfural solution from the second liquid phase, extracting the furfural solution with a liquid parain hydrocarbon to separate glycerides therefrom, leaving in the furfural a concentrate comprising unsaponifiables and saponifiables, saponifying the saponifiables and extracting unsaponiables with a petroleum hydrocarbon.

2. The process of claim l wherein the glyceride oil is soya bean oil.

3. A method of treating glyceride oil containing glycerides of different degrees of unsaturation, which comprises extracting the oil with a liquid polar solvent which is a selective solvent for the more unsaturated glycerides of the oil to provide a polar solvent solution, which contains unsaturated glycerides and a second liquid phase which contains relatively more saturated glycerides, separating the polar solvent solution from the second liquid phase, extracting the polar solvent solution with a liquid paraffin hydrocarbon to separate glycerides therefrom, leaving in the polar solvent a concentrate, comprising unsaponiables and saponifiables, saponifylng the saponifiables and extracting the unsaponiables with a liquid hydrocarbon.

4. The process of claim 3 wherein solvent is vaporized from a portion of the polar solvent solution separated from said second liquid phase and thereafter said portion is recycled as a reflux in extracting further glyceride oil with polar solvent.

5. The process of claim 1 wherein furfural is vaporized from the concentrate before the saponifiables are saponified.

STEPHEN E. FREEMAN.

(References on following page) Number Name Date REFERENCES CITED 2,355,605 Ruthrui Aug. 15, 1944 The following references are of record in the OTHER REFERENCES le ot this patent:

5 Ruthru. et a1., Transactions of American In- UNITED STATES PATENTS stitute of Chemical Engineers, August 25, 1941, Number Name Date pages 649-667. 2,349,271 Baxter May 23, 1944

Claims (1)

1. A METHOD OF TREATING GLYCERIDE OIL CONTAINING GLYCERIDES OF DIFFERENT DEGREES OF UNSATURATION WHICH COMPRISES EXTRACTING THE OIL WITH FURFURAL TO PROVIDE A LIQUID FURFURAL SOLUTION WHICH CONTAINS UNSATURATED GLYCERIDES AND A SECOND LIQUID PHASE WHEN CONTAINS RELATIVELY MORE SATURATED GLYCERIDES, SEPARATING THE LIQUID FURFURAL SOLUTION FROM THE SECOND LIQUID PHASE, EXTRACTING THE FURFURAL SOLUTION WITH A LIQUID PHASE, EXTRACTING THE BON TO SEPARATE GLYCERIDES THEREFROM, LEAVING IN THE FURFURAL A CONCENTRATE COMPRISING UNSAPONIFIABLES AND SAPONIFIABLES, SAPONIFYING THE SAPONIFIABLES AND EXTRACTING UNSAPONIFIABLES WITH A PETROLEUM HYDROCARBON.

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