US2573899A

US2573899A - Solvent fractionation of glyceride oils

Info

Publication number: US2573899A
Application number: US34454A
Authority: US
Inventors: Stephen E Freeman
Original assignee: Pittsburgh Plate Glass Co
Current assignee: PPG Industries Inc
Priority date: 1948-06-22
Filing date: 1948-06-22
Publication date: 1951-11-06
Anticipated expiration: 1968-11-06

Description

Nov. 6, 1951 s. E. FREEMAN 2,573,899

SOLVENT FRACTIONATION OF GLYCERIDE OILS Filed June 22. 1948 1 FlG.3

r------39 x? runrum. |s-1 9 J s|-| P53 23 '5 59 LOIL to B E E 11L I F16. 1 n 2k mnnnmon $52 m us I I23 +fl43 FIG 2 Ar ig INVENTOR. BY sT-EPaeN A. FREEMAN AT T 012M Patented Nov. 6, 1951 SOLVENT FRACTIONATION F GLYCERIDE OILS Stephen E. Freeman, Pittsburgh, Pa., assignor to Pittsburgh Plate Glass Company, Allegheny County, Pa., a corporation of Pennsylvania Application June 22,1948, Serial No. 34,454

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 unsaturation, 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 invention further relates to the preparation of concentrates of sitosterol, stigmasterol, inhibitols, vitamins and the like such as are particularly to be found in soybean oil.

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, inhibitols, or the like which may be objectionable therein;

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

Thirdly, to obtain a concentrate of free fatty acids and unsaponifiables such as sterols, inhibitols, 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, and low in 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.

A fifth object of the invention is to provide an abundant and inexpensive concentrate of sitosterol, stigmasterol, inhibitols, vitamins and the like which are particularly abundant in soybean oil.

A sixth object of the invention is to obtain a more saturated fraction of glyceride oil, low in color and free fatty acids and which is more desirable for conversion into food products than the original oil.

These and other objects will be apparent from consideration of the following specification and drawings in which Figures 1, 2, and 3 illustrate diagrammatically the application of the princl-- ples of the invention.

25 Claims. (Cl. 260-4285) Broadly stated, these objects are attained by the steps involving as one stage contacting a glyceride oil comprising as its main components, triglycerides of the various saturated and unsaturated fatty acids as herein described, with furfural so as to obtain a solution in the furfural of a concentrate of the more unsaturated glycerides. As another stage, the invention involves or comprises contacting the solution of oil and furfural with paraffinic naphtha under such conditions that there is obtained a naphtha rich raffinate phase and a, furfural rich extract phase. As a third stage, the various extraction media are evaporated off torecover the desired fractions of the oil.

One embodiment of the invention would involve treatment of mixed fatty glycerides, e. g. linseed oil or soybean oil with a selective polar solvent such as furfural or ethyl acetoacetate or the like, to obtain two liquid phases. The phase comprising the solvent and the more unsaturated glycerides could then be treated by batch or by counter-current or concurrent extraction with hexane or other hydrocarbon to pull out additional saturated glycerides, thus leaving a higher concentration of unsaturates in the fraction obtained from the solvent.

It has heretofore been recognized that natural glyceride oils such as soybean oil, linseed oil, cottonseed oil, menhaden oil, fish 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, 'wcopherols, 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 differ among themselves primarily by reason of differences 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 films. Certain other oils, such as soybean 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 also susceptible of use in paints and varnishes.

In my prior Patents Nos. 2,200,390 or 2,200,391, of which this application is a continuation-inpart, 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 efiect 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.

In accordance with the present invention, glyceride oils, preferably containing naturally occurring unsaponifiables and usually comprising mixtures of unpolymerized glycerides of varying degrees of unsaturation, free fatty acids, sterols, tocopherols, inhibitols, break" constituents, vitamins and many other non-saponifiable ingredients are extracted with a selective polar solvent, and the resulting extract is extracted with naphtha to remove glycerides from the extract and to leave in the polar solvent a concentrate of the unsaponifiables. Sharp fractiona-e tion can be conducted according to this invention whereby there are produced respectively; a concentrate of relativel saturated glycerides, a concentrate of relatively unsaturated glycerides, and a concentrate of unsaponifiables which contains only a minor amount (generally not more than about 3 percent on the basis of the original oil) of glyceride. For example, when the polar solvent used for the contemplated extraction is furfural and the oil subjected to extraction contains break, there is obtained a first rafilnate of low solubility in furfural. This fraction will vary in amount dependent upon the all 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 rafiinate 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 (11' present) and soluble unsaponifiables. The extract solution is then extracted with paraffinic naphtha to leave in the polar solvent a fraction low in glyceride content and high in free fatty acids and unsaponifiables 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 parafilnic 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 4 obtain a concentrate of fatty acids and unsaponifiable constituents as above described may be effected in accordance with the provisions of the present invention by means of a two column or a three column system in the first of which the whole oil is first 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 cellusolve, 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 or only partially miscible with naphtha may be used. Extraction with furfural is especially meritorious. When the oil is so treated in the first 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), 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 paraflinic hydrocarbon such as naphtha whereby to remove nearly all of the glyceride oils of the extracted phase from the first column together with the major 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, unsaponifiables 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 first column and the crude or degummed oil usually plus 10 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 raffinate may be stripped of residual solvent first by vacuum distillation, then by vacuum and steam and may be treated to remove break, if so desired in accordance with conventional procedures.

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 glycerides leaving 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. 'lhis product is comparable to an extract produced from an alkali refined, break free feed oil.

The by-product remaining in the iurfural is a concentrate of the coloring matter, free fatty acids and unsaponifiable matter. The unsaponifiaole 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 unsaponifiable 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 raiilnate; 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 unsaponiflable matter, free fatty acids and coloring matter in a by-product amounting generally to 0.5% to 3% of the original oil, and; fourthly, a rafllnate which is refined in respect to free fatty acid and certain coloring pigments such as chlorophyll and which can be more easily processed into food products.

Apparatus suitable for use in the practice of the invention is illustrated diagrammatically in the figures of the drawing. The apparatus includes columns I, II, and III, the first 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 soybean oil, linseed oil, fish liver oil, cottonseed oil, peanut oil or the like is stored in a container l and may be diluted with naphtha in an amount, say of to 20% fed into the oil from container II by means of a feed line [2. The oil or the oilnaphtha mixture is fed into the middle portion of column I by means of a feed line l3 at such rate as can conveniently pass through the column with phase separation. A reflux of naphtha, optionally, may also be supplied to the bottom of the column by means of feed line H from the container II. The flow of liquids through the various feed lines l2, I3 and I4 is regulated by means of suitable valves l6 and ll of conventional design.

As stated in my copending application, Serial No. 34,453, and filed of even date (page 7), approximately 0.1 to 1.5 volumes of naphtha per volume of oil normally is used for such reflux.

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 18 connected to a, suitable source (not shown) of supply. The raflinate phase comprising the more highly saturated glycerides together with the major portion of the break constituents of the oil (it they are present) passes out at or near the top of the column and is passed through line l9. to a still 2| for vacuum distillation of the solvents dissolved therein. The solvent free raflinate oil passes out through line 22 to storage or-for further treatment. If desired the rafiinate may be sent to a fourth column (not shown) and refractionated in a manner similar to that desncilribggl above. The solvent is drawn oil through .The percent of the feed oil in the rafflnate may vary. but usually will be within a range of 10 to dependent upon the character or 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 percent of rafiinate canbe controlled by varying the solvent ratio, the temperature, theamount of naphtha in the feed oil or the amount of naphtha or oil reflux feed.

The extract solution which contains the remainder to 15%) 01' the feed oil and which comprises as its main constituents most of the solvent saturated with the more highly unsaturated glycerides passes out through line 24 near the bottom of the column and optionally may pass in its entirety through line 25 directly to the top of column 11 or a portion may pass to a still 26 where some or all of the solvent is stripped of! 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) through line 29 to the top of column 11. 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 fiow 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 to of the furfural is removed before the solution is fed to column 11.

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 11. 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 59 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 lower 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, or partially miscible, 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) or the original oil is obtained through line 42 from the still 38.

The extract from column II comprising the polar solvent having dissolved therein, most of the free fatty acids, small amounts of unsaturated glycerides, 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 ofi at 46 to storage or for further treatment in order to fractlonate out the various components. The solvent from the distillation may be returned from the still through line ll for reuse or for storage as may be desired.

8 Column feeds Oil feed to column I, 12% by weight naphtha Furiural feed to column I, 8 to 1 based on oil teed rate In some instances it may be desirable to wash the naphtha solution of oil passing out through ig i to column to 1 based on on feed line 31 from column II with additional polar solvent such as furfural. This wash may be of low 3 331: zgg g 1 b d n volume, e. g. 1 to 1 on the basis of the oil fraction d te m o and is designed to reduce the free fatty acid con- 8e P d t t tent. This may be accomplished in column III To a into the bottom portion of which it is discharged by feed line 48 branching from line 31. Valves Product 1%? Extract Raflinate 33 49 control the flow of naphtha and oil to (301111111111; III and still 38. Furfural or other polar so ven immiscible, or partially miscible, with naphtha is i%f.f?f..f :a;as: 11:11:: 52. 3 46. 3 fed into the top of the column by line 5|, and g gg m g 3 the extract of solvent and acids or other furifural soluble impurities from the naphtha-glyceride solution passes 011 through the line 52. The naph- RUN 3LINSEED tha and the glycerides, together with vitamin A OPERATING Conmrrons or other oil soluble vitamins (if present) pass off column temperatures through line 53. Of course, the naphtha solu- I c R tion from column III can be vacuum distilled to n 66 710 E eliminate the solvents, thus providing a refined oil fraction, free of or low in break, color, odor, Column feeds inhibitols, free fatty acids and the like. The polar on feed to column I, 12% by weight naphtha solvent extract from column III is a concentrate -m feed t column I, 6 t 1 based on of all the latter constituents remaining in the fed t a polar solvent. Oilrefiux to column I, .67 to 1 based on oil feed The following tables contain the operating cont ditions and product data for extracting and ren p t rgflux t column none fining c tto d S y and linseed oil Naphtha feed to column II, 4' to 1 based on oil in a system such as that above described. In feed rate these runs, column I was operated with naphtha p u data saturated furfural, column II was operated with naphtha to extract the glycerides from the fur- Original fural extract of column II, and column III was Pmduct Oil Extract Product operated with naphtha saturated furfural as an extra wash for the naphtha solution from 001- T m from line s7 19 43 1mm 11. retina-vat; fffi'ffj: "ii' 196. 2 13312 11533 Acid Value 2.33 1.3 1 2 39.0 RUN NO. 1.COTTONSEED OIL The following example illustrates the use of OPERATING CONDITIONS furfural saturated with water as a medium for Column temperatures extracting a glyceride oil in column I. The wet I 1 3 furfural solution was then further extracted with n 32 naphtha in column II. There were no refiuxes of 11 2 naphtha or extracted oil. The furfural solution was fed directly to column II. The oil treated Column feeds was soybean oil of 140.4 iodine value. Operating Oil feed to column I, no naphtha conditions were as follows Furfural feed to column I, 3 to 1 based on oil feed COLUMN I rate Feed rates, parts by volume 011 80: Furfural 160 Reflux feed to column I, none o o Naphtha feed to column II, 1 to 1 based on oil Tempera'gues" Furfural feed 16 feed rate 13 Furfural feed to column III, 1 to 1 based on oil COLUMN II feed rate no Feed: extract solution from column I Product data Naphtha feed, 15 parts by volume Temperature, 21 0. Product g Extract Rafllnate 315;, Results Taken from line 37 19 43 Extracted By-product ield .per cent 81.2 16.5 2.3 011 (Naph- Rail. (Col. (Furlural Iodine Value 110. 2 111. 9 90.1 122. 0 tha solu. I) residue Acid Value 2. 0. 9 1.1 54.0 Col. 11) Col. IV)

Yields, Per Cent 1. as 95. a 2. s4 RUN NO. 2-SOYBEAN OIL l0 Iodine Value 149.5 139.2 140.5 Per Cent Unsaponiflable..-. 2. 98 1.40 7.64 OPERATING CONDITIONS Column temperatures The efl'ects of backwashing a turfural solution I 113-115 F. of oil slightly higher in iodine value than the II 53-57 F. original oil with varying proportions of naphtha are illustrated by the following examples. (A) soybean oil of an iodine value of 133.5 was sub- Jected to a single stage primary extraction at 110 F. with furfural in a ratio of parts by vided into four parts, 3 B B B and the parts backwashed with different proportions of naphthg. The temperature in each instance was 11 F.

iodine value thanthe original oil, it is possible to obtain a naphtha extract oil of lower iodine value than the original oil. The above examples Furfural extracted oil=55.3% original oil Iodine value extracted oil=150.2

The extract solution'taken from column I operating under the above conditions was diweight per part of oil. An extract solution in 5 sample B1 furfural of oil of 137.2 iodine value was obtained. The yield of extract oil was 58%. The solution Weight Sample So ut o 1072 was divided into three parts (A A A which Weight 0! p were then backwashed as follows:

sa p e A! 10 Oil Products I Weight of sample solution, 1096 Naphtha Furfural Weight of naphtha, 22.5 Temperature of system 110 F' Yields in per cent original oil 4 9 50 l 15 Iodme'va1ue...- IIIIIIIIIIIIIIIII 14318 15011 011 Products Naphtha Furfural Sample B extract extract Weight of sample solution. 1042 Yields, percent no.4 41.4 Weight of naphtha, 44.6 Iodine values 130. 3 139. 2

" Original oil.

Sample A r i s mm llgurfural Weightof furfural-oil solution, 1033 Weight of naphtha, '70 Temperature of system, 110 F. i gkfifr fifi ff f fi .fEIIIIIIIIIIIII: 11:3 151?:

Oil Products v sample B3 ig g g g f g Weight of sample solution, 1069 e c Weight of naphtha, 10.3 Yields. per cent original oil 25.2 32.8 I Iodine values 131. 6 142. 2 Oil Products 11 Sample A l I x tra l? 5%;?

Weight of sample solution, 1097 40 Weight of naphtha. 1 ioiifli'viitfiiiiifififfli2113;132:1133: 131 i 123?? Temperature of system, F.

on Products Sample 4 Weight of sample solution, 959 13m 1 1:? Weight of naphtha, 7s

Yields, per cent of original oil 2. 38 55. 7 Oil Products Iodine value 129. 8 13. 81

.50 Naphtha Furfural I Extract Extract It is of interest to observe that where the oil which is backwashed in furfural solution ,is only' ms t o i 3L3 2M moderately (about 8 points or less) higher in Io ine v% 1:fi ..-ff fini.--. 145.1 154.1

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

The application of a reflux of naphtha in treating a glyceride oil with furfural following by an extraction of nearly all of the glycerides from the furfural solution may also be described as follows:

The apparatus employed in the process is indicated in Figure 3 of the drawings. It comprises a column 60 for extracting the oil with polar solvent. This column is provided somewherenear the mid-section with an inlet 6| for the oil to be treated and in a zone near the top is provided with an inlet 62 for polar solvent such as furfural. A reflux of naphtha may be introduced in a zone near the bottom of the column as indicated at,63. The inlets 62 and G3 are spaced from the ends of the column sufliciently to provide clearing zones 60a and 60b to permit adequate separation of the phases before they are withdrawn from the system.

Raflinate oil containing naphtha is withdrawn at the top of the column as indicated at 64. The raflinate solution also contains small amounts of furfural and may be passed to sui able distillation apparatus (not shown) where it may be subjected to steam or to the appropriate distillation or drying operation in order to remove the solvents and to obtain a raflinate of relatively low iodine value.

An ex ract solution of oil of high odine value enrich d in free fatty acids, unsaponiflable matter, coloring matter and various other constituents is withdrawn from the column as indicated at 65 at the lower extremitv of the lower clearing zone. The extrac ed so ution is passed to a column 66 at a point sufficiently b low the top thereof to provide a clearing zone 66a.

A naphtha backwash designed to extract nearly all (95% or more, i. e. about 97%, upon the basis of the ori inal oil) of the glycerides from the extract solution is in roduced into the column 66 as indicated at 61. The point of introduction preferably is sufficiently above the bottom of the column to provide a clearing zone 66b.

The naphtha solution of oil extracted from the furfural in the column 66, is withdrawn from the top of the latter column as indicated at 68 and may be passed to appropriate distillation apparatus where the non-oil constituents such as naphtha and any residual furfural are removed by distillation to obtain glyceride oil of high iodine value relatively free from fatty acids, unsaponifiable matter and such like constituents. Vitamin A, if present, appears in high concentration in this oil.

The furfural containing only a small amount of glycerides, but a high concentration of free fatty acids, unsaponifiable matter, coloring matter and the like constituents is withdrawn as indicated at 69 from the lower portion of the clearing zone of the column 66.

It is to be understood that the

columns

60 and 65 may be provided with suitable packing such as Raschig rings, Berl saddles or any other material designed to effect thorough distribution of the liquids passing through the column and thus to induce complete contact for the different media which are withdrawn from the column. The packings may be supported upon perforate plates or baiiies. Such plates may be disposed at any convenient intervals in the column. The packings may be replaced if desired, with bubble plates or any other suitable apparatus designed thoroughly to commingle the liquids and to prevent channeling.

Specific dimensional and operating data actually employed in a commercial run are tabulated as follows:

A. Primary column 60 1. Total height, 84 ft., 8 in. 2. Packed height, 66 ft., 3 in. 3. Clearing sections a. Top, 3 ft, 6 in. b. Bottom, 8 ft., 3 in. 4. Diameter of column, 22 in. 5. Feed positions (height from bottom of column) a. Furfural, 80 ft., 10 in. b. 011. 32 ft.. 8 in. c. Naphtha reflux, 7 ft., 10 in. 6. Phase interface position-from 23 ft, in, to

30 ft., 5 in. from bottom of column. 7. Condition of operation column 60 a. Rates Ratio to GalsJhr.

Furiural 250-350 Oil 50- Naphtha reflux b. Temperatures (1) Top of column, 107 to 115 F. (2) Bottom of co1umn, 103 to 108 F. (3) Furfural feed, 108 to 115 F. (4) Oil feed. to F. (5) Naphtha reflux feed, 104 to 107 F.

B. Secondary column 66 Feed.

. 1 Extract solution"; All from primary column 60 hth -168 2. 4-1

Nap a b. Temperatures (1) Top of column. 64 to 78 F. (2) Bottom of column, 58 to 65 F. (3) Extract solution, 65 to 80 F. (4) Naphtha, 58 to 65 F.

C. Quality of feed oils used The oils used in these runs were degummed soya oil whose constants fell within the following ranges:

Iodine value, 129.3 to 137.3 Percent free fatty acid, 0.28-0.99 Color (Gardner), 9 to 10% Percent chlorophyll, .00014-.00034 Percent carotene, .0041-.0068

D. Quality of products produced Per Cent Exggent Product Per Cent Raitraot flnate Per Cent Yield 26. 2-37. 8 Iodine value 151. 4-153. 0 Per cent free fatty acid- 0. 2-0. 8 Per cent tocopberol Per cent unsaponifiable matter An important feature of the invention resides in the fact that the raflinate or more saturated glyceride oil fraction is refined in the process. The process, as previously described, is adapted to the use of either crude or refined oils as feeds and is especially well adapted to the use of degummed oils such as degummed soya oil. Normally, because of the relatively high acid value 'and presence of objectional natural pigments,

crude or degummed oils must be alkali refined and bleached for the removal of these objectional constituents before the oil may be processed into troleum naphtha or other suitable solvent.

13 food products such as salad oils or hydrogenated products.

In the above process where degummed soya oil is used as the feed oil, the major portion of the free fatty acid and certain objectional pigments, notably the chlorophyll, are removed with the extract fraction, leaving a raflinate relatively free of fatty acid and chlorophyll. The break constituents concentrated in this fraction may be removed by light alkali refining, water degumming or other conventional methods. The raffinate oil produced by this process is therefore refined in respect to free fatty acid and chlorophyll and may be processed into food products in a more simple and economic manner.

Typical data illustrating percentage chlorophyll reduction of a rafiinate treated as above described, are as follows:

The chlorophyll content of the low iodine .value fractions is about one tenth that of the original oil. These rafilnates of low chlorophyll content can be readily processed to white shortening.

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 raffinate from column I and refined extract oil in a naphtha wash from column II. In such process it is desirable to make the raflinate 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, and sterols as partially or completely separated components. A convenient process of so treating the by-product comprises distilling the furfural saponifying the free acids with alcoholic sodium or potassium hydroxide. The soaps can be dissolved in water and the sterols, inhibitols, tocopherols, and other unsaponifiable constituents dissolved out in pe- 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: 1) Twitchellizing the stock to form fatty acids, distilling the fatty acids and recovering the unsaponifiable 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 unsaponifiable matter from the still bottoms in the conventional method described above.

The present invention contemplates the further treatment of the by-product oil as obtained by the extraction of the glycerides from the soybean oil extract by application of petroleum naphtha. Such process is disclosed in my co-pending application, Serial No. 516,658, filed January 1, 1944, now abandoned, and entitled, Fractionation of Soybean Oil.

In the application of such a process, the apparatus disclosed in Figure 2 may be employed. Of course, the operations could be performed with varying degrees of efliciency and other embodiments of apparatus. The apparatus shown includes two columns III! and III respectively disposed in suitable lay-out in proximity to a tank II2 for oil, namely soybean oil, a tank H3 for polar solvent such as furfural and a tank I It for hydrocarbon such as naphtha. For purposes of maintaining most eflicient operating temperatures, all of these may be jacketed as indicated at H6, H1, H8, H9, I20 respectively and each jacket may be provided with inlets I22 and outlets I23 or' by circulation of temperature controlling medium (such as water) therethrough. The jackets upon the columns III) and III may be further divided into upper and lower sections Ill-I25 and I26-I2I, in order to admit of establishment of a temperature gradient within the extraction zones.

Container II2 discharges oil to be extracted through feed line I29 to the mid section of column III! and polar solvent (e. g. furfural) is fed from container II3 to the upper zones of the same column by line I3l. Raflinate oil saturated with solvent passes off from the top of the column through line I32. It can be stripped by distillation and then stored. It is to be understood that all feed lines, wherever required for purposes of maintaining fiow, can be equipped with pumps I33.

The extract from column IIO, consisting of polar solvent charged with the more unsaturated glycerides, the sitosterol, stigmasterol, inhibitols, vitamins E, A, free fatty acids and other minor constituents, discharges through line I34 near the bottom of the column and is fed in at the top of column III for extraction of the major portion of glycerides. The line I34 may be equipped with a still I35, for evaporating ofi solvent. A portion of the extract concentrated to a solvent content of about 10% can then be v recycled through line I35a, as a reflux. Alternatively still I35 may be used to concentrate the feed to column III with a resultant reduction in the quantity of hydrocarbon required in column I I I to extract the glyceride oil from the solution. Hydrocarbon (e. g., naphtha) from tank H4 is fed in near the bottom of the column III by line I36. A line I36a from the tank, also connects to tank II2 whereby the feed oil in the latter can bepreadmixed with 10 to 15% of naphtha for purposes of promoting countercurrent flow of the oil and the polar solvent in column III). This may also be accomplished by pumping proportional amounts of naphtha from tank II4 through line I36a and by-pass I36b directly into line I29, which is the oil feed to column H0. Valves I360 permit of control of the direction and ratio of fiow through the lines I36a and I3Bb.

Rafiinate consisting largely of hydrocarbon and the more unsaturated component of the original oil is drawn off through conduit I31 at the top of container I I I. The extract now consisting largely of polar solvent containing the concentrate of unsaponifiables and free fatty acids is drawn oil at the bottom through conduit I38. Its further treatment will be described later.

In order to improve the richness of they extract from column III! in unsaturated glycerides and increase the yield of free fatty acids and unsaponiflables, a portion of the raflinate from column III may be drawn off through conduit I39 and recycled to'provide a reflux to the lower zones of column I II). If desired, the line I 39 may be provided with a still I for'removal of hydrocarbon in the reflux, the hydrocarbon condensate being returned to tank Ill by line I 42.

The solvents are removed from the three frac-- tions obtained respectively from outlet lines I32, I31 and I38 by distillation in accordance with conventional practice.

It is desirable that the oil and solvents in the system be maintained continuously under a blanket of carbon dioxide, nitrogen or nonreactive gas. The gas may even be bubbled in gently through conduits I43. It is removed in the distillation operations or is bled off through suitable outlets, such as vent pipes (not shown) at the tops of the containers.

Operating conditions and proportions will vary for different solvents in the system. Assuming that furfural is employed as a polar solvent and parafiinic naphtha as the hydrocarbon for stripping off the glycerides dissolved therein, the temperature in column IIIl may be approximately 129 to 131 F. That in column III may be approximately 60 to 80 F. Furfural saturated with naphtha may be fed into column I III in the ratio of 6 parts to 1 of feed oil. The feed oil may contain 14 percent of naphtha. to promote flow in the column. Naphtha in the ratio of 4 parts by volume to 1 of feed oil may be fed into column III.

In a run where the original oil was of an iodine value of 128-129: That of the raffinate from column III) was 113.2; that of the raflinate from column III was 144.7; and that of the extract from column III was 137.6. The yields of railinate from columns III) and III and extract from column III were respectively 46.9%, 51.5% and 1.6%.

If it is desired to obtain further unsaponiflables from the raflinate from column III), it may be further partially dissolved in solvent such as furfural, at a temperature of 8 or 10 F. higher than that employed in the first extraction.

Of course various uses and treatments of the different fractions obtained are contemplated. The uses and treatments of the two raflinates may be conventional. The rafiinate from column III] is low in unsaturates and it is well adapted for use in foods and soaps. For such purposes, it may be further treated with caustic to remove break and mucilagenous substances. refining is well understood. The extract from column I II which is of particular interest in this case constitutes about 1 or 2 percent of the original oil and comprises probably 8% of unsaponifiables. After it has been separated from furfural it can be used directly for some purposes.

' for example, it can be returned directly to the A preferred method is to treat the concentrate with one of the lower alcohols such as methyl alcohol or ethyl alcohol in a proportion in excess of the total fatty acid radicals available as glycerides or as free fatty acids and an' acid such as sulfuric acid or other hydrolyzing agent in a Caustic manner well understood in the art in order to convert the fatty'acid radicals into esters of the lower alcohol. This treatment is then followed by water washing and distillation at a temperature to remove excess lower alcohol and glycerol and so forth leaving a residue of esters of free fatty-acids and the lower alcohols and the unsaponiiiable materials comprising sitosterol, stigmasterol, vitamin E and so forth. The esters of lower alcohols are distilled oil preferably under vacuum to leave a residue of a high concentration of sitosterol, stigmasterol, vitamin E and other unsaponifiable matters which may then be separated from each other by conventional methods available to the art.

I claim:

-1. A process of treating a natural glyceride oil which contains fractions of different degrees of unsaturation in order to obtain therefrom a fraction comprising relatively highly saturated glycerides, a second fraction comprising relatively highly unsaturated glycerides, and a third fraction comprising free fatty acids and unsaponiflables which process comprises dissolving 10 to 25% of naphtha'in the oils, effecting an initial fractionation of said oils by extraction with furfural to obtain two liquid phases, one comprising the more highly saturated glycerides containing a small amount of furfural dissolved therein and the second comprising the more highly unsaturated glycerides, free fatty acids and unsaponiflables dissolved in furfural, then treating the latter phase with naphtha to split it into two additional phases, one comprising the more highly unsaturated glycerides dissolved in the naphtha and the other comprising furfural containing dissolved therein the major portion of the unsaponifiables, free fatty acids and a minor amount of glycerides of a relatively highly unsaturated nature.

2. A process of treating natural glyceride oils comprising mixtures of glycerides of fatty acids of different degrees of unsaturation, free fatty acids. "break" constituents and unsaponifiables in order to separate them into fractions, which process comprises extracting the oil with furfural in a ratio within a range of about 3 to 15 parts per part of glyceride oil to obtain two liquid phases, one comprising a rafllnate enriched in highly saturated glycerides and containing dissolved furfural and an extract phase comprising oil enriched in more highly unsaturated glycerides, free fatty acids and unsaponifiables dissolved in furfural, then in a second stage extracting the later phase with naphtha to remove the glycerides and to leave in the furfural a concentrate of fatty acids and unsaponifiables, distilling ofi the solvents from said concentrate to obtain a fraction comprising free fatty acids, unsaponifiables and a small amount of glycerides, then saponifying the fatty acids and glycerides of the fraction with alcoholic caustic, dissolving the resultant soaps of the fraction in water and extracting out the unsaponifiables with naphtha.

3. A process of treating natural glyceride oils comprising mixtures of glycerides of fatty acids of different degrees of unsaturation, free fatty acids, break constituents and unsaponiflables in order to separate them into fractions, which process comprises extracting the oil with furi'ural in a ratio within a range of about 3 to 15 parts per part of glyceride oil to obtain two liquid phases, one comprising a raifinateenriched in highly saturated glycerides and containing dissolved furfural and an extract phase comprising oil enriched in more highly unsaturated glycerides, free fatty acids and unsaponifiables dissolved in furfural, then in a second stage extracting the later phase with naphtha in a ratio generally within a range of 1 to 10 parts per part of oil to remove the highly unsaturated glycerides and to leave in the furfural a concentrate of free fatty acids and unsaponifiables.

4. A process of treating linseed oil in order to separate it into fractions, each fraction being enriched in a component of a natural oil, which process comprises extracting the oil with furfural in a ratio within a range of about 3 to 15 parts per part of oil to obtain two liquid phases. one comprising a raffinate less' than 50% of the total oil enriched in relatively highly saturated glycerides and containing some dissolved furfural and an extract phase comprising more than 50% of the total oil and being enriched in more highly unsaturated glycerides, free fatty acids and unsaponifiables dissolved in furfural, and subsequently extracting the latter phase with naphtha to remove the major portion of the glycerides and to lave in the furfural a concentrate of free fatty acids and unsaponifiables with not more than 5% of unsaturated glycerides (on the basis of the feed oil) dissolved therein.

5. A process of refining linseed oil comprising mixtures of glycerides of fatty acids, free fatty acids, break constituents and unsaponifiables which oil contains fractions of different degrees of unsaturation, which process comprises extracting the oil with furfural to obtain an extract constituting about 70 to 85% of the oil and containing the furfural soluble unsaponifiables, glycerides and free fatty acids together with a ramnate comprising the rest of the oil containing the break constituents of the natural oil and being substantially free of fatty acids and furfural soluble unsaponifiables, then treating the extract with naphtha to dissolve out about 97% of the glycerides from the furfural and to leave a concentrate of free fatty acids and unsaponifiables in the furfural.

6. A process of refining soybean oil comprising mixtures of glycerides of fatty acids, free fatty acids, break" constituents and unsaponifiables which oil contains fractions of different degrees of unsaturation, which process comprises extracting the oil with furfural to obtain an extract constituting 15 to 70% of the oil and containing the furfural soluble unsaponifiables, glycerides and free fatty acids, and further to obtain a raffinate comprising the rest of the oil and the "break constituents of the natural oil and being substantially free of fatty acids and furfural soluble unsaponifiables, then treating the extract with naphtha to dissolve out about 97% upon the basis of original oil of the glycerides from the furfural and to leave a concentrate of free fatty acids and unsaponifiables in the furfural.

18 acids with a lower aliphatic monohydric alcohol and distilling off the resultant esters to provide said concentrate.

9. A method of obtaining a concentrate of unsaponifiables comprising sitosterol, stigmasterol, inhibitols, vitamins and the like from soybean oil, which comprises extracting the oil with furfural to obtain a furfural solution of said unsaponifiables, fatty acids, and glycerides of fatty acids, extracting the furfural solution with paraffinic naphtha to remove the glycerides, treating the unsaponifiables containing the free iatty acids with a lower aliphatic alcohol to form esters of the fatty acids and distilling off the fatty acid esters.

10-. A method as defined in claim 9 in which the alcohol contains 1 to 2 carbon atoms and is monohydric.

11. A method as defined in claim 9 in which the alcohol is methyl.

12. A process of obtaining glyceride oils of high iodine value and good color and relatively low free fatty acid content from a low iodine value oil and containing coloring matter and free fatty acids, which method comprises counfural is introduced near the top, and the oil at a point below the point of introduction of the furfural, and .1 to 1.0 volume of naptha is introduced as a reflux at a point below the introduction of the oil, whereby to obtain a furfural extract solution of oil high in iodine value and by-products, withdrawing said extract solution from the extraction zone at a point near the bottom thereof, and extracting the glycerides from the furfural solution by counter-currently flowing the solution against naphtha in a second zone, the naphtha being in a proportion of at least 1.0 volume per volume of original oil.

13. In a process of obtaining a mixture of sitosterol, stigmasterol and inhibitols from the concentrate thereof which results from extraction of soybean oil with a polar solvent partially miscible with the oil, to obtain a solution of unsaturated fatty glycerides, free fatty acids, sitosterol, stigmasterol, inhibitols and vitamins and extraction of the solution with naphtha to remove the unsaturated fatty glycerides; the steps which comprise esterifying the fatty acids of the concentrate with a lower alcohol and distilling off the fatty acid esters of the lower alcohol thus formed to leave the desired mixture of sitosterol, stigmasterol and inhibitols.

14. In a process of obtaining a mixture of sitosterol, stigmasterol, inhibitols and vitamins from the concentrate thereof, which results from the extraction of soybean oil with furfural to obtain a solution of unsaturated fatty glycerides, free fatty acids, sitosterol, stigmasterol, inhibitols and extraction of the solution with na htha to remove the fatty glycerides; the steps which comprise esterifying the fatty acids of the concentrate with a lower alcohol, and distilling oi the fatty acid esters of the lower alcohol thus formed to leave the desired mixture of sitosterol, stigmasterol and inhibitols.

15. The process of claim 1, wherein the oil is soybean oil.

16. The process of claim 1. wherein the oil is linseed oil.

17. A process of obtaining a fraction of glyceride oil of high iodine value, good color, and relatively low free fatty acid content from an 011 19 of low iodine value containing substantial amounts of the foregoing impurities, which method comprises the steps of countercurrently flowing the oil to furfural by introducing furfural into an upper part of an elongated extraction zone, and oil into the same extraction zone at a point below the point of introduction of furfural, then further introducing a reflux of naphtha at a point below that of introduction of the oil in an amount and at a temperature to obtain a furfural extract solution comprising to 90% of the oil, withdrawing the iurfural extract solution at the bottom of the extraction zone, then further extracting at least about 97% of the glycerides of the oil from the furfural extract solution with naphtha in a second extraction zone, and evaporating the naphtha to recover the fraction.

18. A process of obtaining a fraction of a glyceride oil of high iodine value, good color, andrelatively low free fatty acid content from a low iodine value 011 and containing coloring matter and free fatty acids, which method comprises countercurrently extracting the oil with three to fifteen volumes of furfural per volume of oil in an elongated extraction zone in which the furfural is introduced near the top and the oil at a point below the point of introduction of the furfural, and 0.1 to 1.5 volumes of naphtha is introduced at reflux at a point below the introduction of the oil whereby to obtain a furfural extract solution, constituting 15 to 90% of the original oil, of oil high in iodine value and by-products, withdrawing said extract solution from the extraction-zone at a point near the bottom thereof and extracting the glycerides from the furfural solution by countercurrently flowing the solution against naphtha in a second zone, the naphtha being in a proportion of l to 10 volumes per volume of original oil, and evaporating the naphtha to recover the fraction.

19. A process as defined in claim 17, in which the oil treated is soybean oil.

20. A process as defined in claim 1'1, in which the oil treated is degummed soybean oil.

21. A process as defined in claim 18, in which .the oil treated is degummed soybean oil.

solution constituting 15-90% of the oil which contains unsaponiflables and relatively more unsaturated glycerides, and a second liquid phase which contains relatively more saturated glycerides. extracting the polar solvent solution with an amount of naphtha sufllcient to extract about 97%. on the basis of the original oil, of the glycerides but insufilcient to extract a substantial amount of unsaponiflables therefrom, whereby to leave in the polar solvent a concentrate of unsaponiflables.

23. The process of claim 22, wherein the polar solvent is furfural.

, solvent liquid phrase from a liquid oil phase,

withdrawing the polar solvent phase at a point in the column below the point of oil introduction, extracting a portion of said polar solvent phase with liquid aliphatic hydrocarbon, removing polar solvent from another portion of said polar solvent phase, and introducing the resultant concentrate into the column at a point below the point of oil introduction.

25. A process as defined in claim 24 wherein the polar solvent is iurfural.

STEPHEN E. FREEMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date- 2,278,309 Freeman Mar. 31, 1942 2,355,605 Ruthrui! et al Aug. 15, 1944 OTHER Ruthruif et al., American Institute of Chemical Engineers, Transactions Section A, pp. 649-667, August 25, 1941.

Bailey, Ind. Oil and Fat Products (1945), Interscience Pub., pp. 655-657.

Claims

1. A PROCESS OF TREATING A NATURAL GLYCERIDE OIL WHICH CONTAINS FRACTIONS OF DIFFERENT DEGREES OF UNSATURATION IN ORDER TO OBTAIN THEREFROM A FRACTION COMPRISING RELATIVELY HIGHLY SATURATED GLYCERIDES, A SECOND FRACTION COMPRISING RELATIVELY HIGHLY UNSATURATED GLYCERIDES, AND A THIRD FRACTION COMPRISING FREE FATTY ACIDS AND UNSAPONIFIABLES WHICH PROCESS COMPRISES DISSOLVING 10 TO 25% OF NAPHTHA IN THE OILS, EFFECTING AN INITIAL FRACTIONATION OF SAID OILS BY EXTRACTION WITH FURFURAL TO OBTAIN TWO LIQUID PHASES, ONE COMPRISING THE MORE HIGHLY SAUTURATED GLYCERIDES CONTAINING A SMALL AMOUNT OF FURFURAL DISSOLVED THEREIN AND THE SECOND COMPRISING THE MORE HIGHLY UNSATURATED GLYCERIDES, FREE FATTY ACIDS AND UNSAPONIGIABLES DISSOLVED IN FURFURNAL, THEN TREATING THE LATTER PHASE, WITH NAPHTHA TO SPLIT INTO TWO ADDITIONAL PHASES, ONE COMPRISING THE MORE HIGHLY UNSATURATED GLYCERIDES DISSOLVED IN THE NAPHTHA AND THE OTHER COMPRISING FURFURAL CONTAINING DISSOLVED THEREIN THE MAJOR PORTION OF THE UNSAPONIFIABLES, FREE FATTY ACIDS AND A MINOR AMOUNT OF GLYCERIDES OF A RELATIVELY HIGHLY UNSATURATED NATURE.