US2569136A

US2569136A - Method of improving color and drying characteristics and similar properties of drying glyceride oils

Info

Publication number: US2569136A
Application number: US158788A
Authority: US
Inventors: Henry A Vogel
Original assignee: Pittsburgh Plate Glass Co
Current assignee: PPG Industries Inc
Priority date: 1950-04-28
Filing date: 1950-04-28
Publication date: 1951-09-25
Anticipated expiration: 1968-09-25

Description

Sept. 25, 1951 H., A. VOGEL I I ,5

METHOD OF IMPROVING COLOR AND DRYING CHARACTERISTICS AND SIMILAR PROPERTIES OF DRYING GLYCERIDE OILS Filed April 28, 1950 Eva/M41652 INVENTOR.

HENRY A. VOGEL ram HTTOE/VE'K Patented Sept. 25, 1951 UNITED STATES PATENT OFFICE METHOD OF IMPROVING COLOR AND DRY- ING CHARACTERISTICS AND SIMILAR PROPERTIES OF DRYING GLYCERIDE OILS Application April 28, 1950, Serial No. 158,788

17 Claims. 1

The present invention relates to a process of treating glyceride oils, and notably glyceride oils of relatively highly unsaturated character, e. g., a drying oil, containing considerable amounts of coloring matter, drying inhibitors, or other constituents which may be objectionable in a drying oil.

An object of the invention is to provide a process of treating a glyceride oil of the above de scribed character, whereby the objectionable constituents, and notably coloring matter and inhibitors of drying are eliminated in a simplified operation, with a minimum of handling and transferring.

A second object is to provide a process of treating extract fractions of unsaturated glyceride oils obtained by solvent fractionation of glyceride oils, with polar solvents, whereby to improve the color and drying characteristics of the oil without substantially impairing the iodine value or greatly increasing the peroxide value thereof.

A third object is to provide a process of the foregoing type, application of which reduces or eliminates break (if it is present).

A fourth object of the invention is to provide a process of the foregoing type which is relatively inexpensive of operation, and which requires a minimum of apparatus and labor.

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

It is well recognized in the art that conventional drying oils, such as linseed oil, soybean oil, sunflower seed oil and others, are composed largely of glycerides of long chain fatty acids. Some of the fatty acid radicals in the glycerides contain a plurality of double bonds which impart to the oils their characteristic drying properties. Other fatty acid radicals are free of double bonds, or at most include but a single double bond, and are of non-drying character. As the proportions of the latter types of acids in the glycerides increase, the drying powers of the oils tend to decrease, and if the unsaturation is reduced unduly, the drying capacity becomes so feeble that the oil is no longer considered a drying oil.

Oils rich in double bonds in the fatty acid radicals are especially suitable for use in the formulation of paints and varnishes, while the oils of relatively highly saturated character are of especial value in the preparation of food products, soaps, and such like materials.

In addition to the glycerides, the oils may, also coloring matter, e. g., carotinoid pigments, chlorophyl, etc. Likewise, inhibitors of drying which are now generally assumed to include tocopherol or vitamin E, as well as phosphatides which produce break, may be present.

In certain prior patents, such as 2,200,390 and 2,200,391 to Stephen E. Freeman, are disclosed processes of treating glyceride oils, and notably the oils employed in the paint and varnish industry, with polar solvents which are but partially miscible with the oil and which have a preferential afiinity for the more unsaturated glycerides. By application of the processes of the patents, the oil may be split into a raflinate fraction including a concentration of the less unsaturated glycerides which are adapted especially for use in food products, and an extract comprising a concentration of the more highly unsaturated glycerides which are of the type adapted for use in paints, varnishes, and similar products which require oils of relatively high capacity for air-drying. In this process, break constituents, including phosphatides if they are present in the oil as initially treated, tend to concentrate in the raffinate or food fraction, but may not be fully removed from the extract. Coloring matter and tocopheral, or similar inhibitors, for the most part follow the extract fraction.

In order to improve the color of glyceride oils, it has previously been proposed to treat them with adsorbent agents, such as fullers earth, acid-activated clays, and other similar materials which have a capacity for adsorbing coloring matter. It has also been common practice to subjectathe oil to a refining operation with alkali, which has a capacity for removing break constituents as well as considerable amounts of coloring matter. In this process, there is substantial loss, owing to the conversion of free fatty acids and the acid radicals of the glycerides into soaps which are eliminated as foots.

In a co-pending application to Roger M. Christenson and Ralph E. I-Iarpt, Serial No. 41,168, of July 28, 1948, now abandoned, it is disclosed that the efficiency of adsorbent agents in the treatment of glyceride oils can be greatly enhanced if the oil, at the time it is treated with adsorbent agent, is also subjected to treatment with live steam. The combination of adsorbent agent and live steam results in a substantially more effective adsorption of coloring matter so that minimum amounts of adsorbent are required. Low losses of oil in bleaching are attained. Also, break constituents, if present, are eliminated or reduced to. such proportions as will result in an oil which will give a negative break test, often without resort to alkali refining. The simultaneous application of adsorbent agents such as fullers earth and steam as disclosed in application Serial No. 41,168 is particularly adapted to treating raffinate oils, from the furfural fractionation by the technique disclosed in Patent 2,200,391, which raifinates are usually relatively rich in break constituents.

In my co-pending application of August 19, 1948, Ser. No. 45,210, is disclosed a process of treating the extract fractions of high iodine value which are applicable to the paint industry, for purposes of eliminating, or reducing. the tocoph erol, or vitamin E content without appreciably impairing the iodine value of the oil. Essentially, the process involves the discovery that by careful treatment of the oil with air or oxygen in the presence of a small amount of a soluble compound of a drier metal, such as a cobalt, tocopherol and'perhaps other inhibitors occurring in the oil can be selectively oxidized to a state in which they no longer interfere with the drying of the oil.

By proper control of the various conditions of operation, this elimination of inhibitors can be conductedto such an extent as to eliminate 50% to 95% of the tocopherol without changing the iodine value of the oil more than 1 or 2 points, and without greatly increasing the peroxide value or the acid value of the oil. Simultaneously, there is also elimination of a considerable amount of color by selective oxidation of pigments and other constituents in the oil. For purposes of providing a drying oil of high iodine value, low inhibitor content, and good color, it has been proposed to subject an oil of high iodinevalue suitable for use in the formula tion of paints and varnishes, to selective oxidation for purposes of. reducing inhibitor content which might tend to slow up the drying of the oil, and' also to eliminate, or at least to improve the color of, readily oxidizable pigments or coloring matter. The oxidized oil was then. subjected to bleaching with a suitable adsorbent agent, such. as'fullers earth or acid-activated. clay, to remove: coloring matter which could not be satisfactorily eliminated by oxidation. However, this combination. process was found to be unsatisfactory, inasmuch as the oxidation of the oil apparently resultedin the modification of pigments or other coloring matter in such manner that the could not. be selectively bound by the adsorent agent.

Concomitant selective aeration of the oil and treatment with adsorbent agent was likewise found. to be unsatisfactory, inasmuch as the oil, inthe presence of both the catalyst of oxidation and the freshly added, or unspent adsorbent agent, tended to undergo severe reduction of iodine value, formation of objectionable amounts of peroxides, and such like changes which were notanticipated.

THE PRESENT INVENTION It has now been discovered that if an oil, such as an oil of high iodine value, containing considerable degree of color, inhibitors and perhaps break,- for example, soybean oil or linseed oil or an extract fraction of such oil, as obtained in the above mentioned Freeman patents, is subjected first to treatment with an adsorbent agent, such as fullers earth or acid-activated clay or a combination of'such adsorbents and while still containing the spent adsorbent agent, is subjected to selective oxidation in the presence of a slightly increased amount of catalyst over that disclosed in the foregoing application Serial No. 45,210, inhibitors are readily removed without appreciably impairing the desired properties of the oil. The oil so treated may be filtered to remove the adsorbent agent, thereby providing a product of excellent drying characteristics which is of low color; break, if present, is also eliminated or reduced in amount.

In the process acid activated clays, which are especially effective in color removal, are usually preferred as adsorbents, but other adsorbents are not precluded. Both the steam bleaching technique of the foregoing application to Christennson and'Harpt and dry bleaching in accordance with more conventional methods are contemplated.

THE APPARATUS Various embodiments of apparatus may be employed in the practice of the invention. The single figure of the drawing illustrates diagrammatically one simple embodiment of such apparatus.

The apparatus may comprise a reactor chamber 10 which preferably is fairly tall, to admit of treating a considerable volume of oil while leaving suflicient head space H to obviate any tendency of the oil to bubble over during treatment with steam, air, or other vaporous or gaseous medium.

This chamber may be provided with any conventional heating device such as coils for electrical heatin jackets for circulation of a heating fluid about the chamber or internal coils adapted to transmit heat to the oil in the chamber by conduction. For purposes of illustration, there is shown a heat exchanger ll having an inlet l2 and an outlet [3 for circulation of heating or cooling fiuid as may be required. For example, in order to heat the oil to be treated, steam or hot water or other hot liquid or vapor may be supplied to the. heat exchanger. On the other hand, if it is desired quickly to cool the oil after treatment, cold water or other cooling medium may be circulated through the exchanger. Oil, the temperature of which is to be controlled, is circulated to the heat exchanger I I through a conduit l4 connected near the bottom of the container. It may be provided with a valve l6 and, for purposes of promoting rapid flow of oil, it may also be provided with a pump indicated diagrammatically at IT. Oil, after passing through the heat exchanger, is returned to the treating chamber l0 through a conduit I8. Any other appropriate system for attainment of desired temperature in the system may be employed.

The chamber is also provided with an inlet conduit i9 having a valve 2|, whereby the introduction of oil to be treated can be effected and the rate of introduction controlled. Treated oil an be drawn oiT at the bottom of the chamber through a conduit 22, having a valve 23. Chamber l 0 is further provided with a well 24, or other appropriate inlet, for the introduction of a thermometer, thermocouple, or other temperature measuring device. It also has an outlet 25 having valve 25a to admit of drawing off samples of oil during the course of the treatment. These samples may be subject to conventional tests for acidity, break, peroxide value, color, tocopherol content, or other values indicative of the progress of the treatment.

The chamber I is provided near its upper extremity with an outlet 26 which extends, asindicated at 28, to provide a connection to a source of vacuum (not shown). Such connection, it will be understood, is optional, inasmuch as it may not be necessary under all conditions to subject the oil to vacuum treatment. However, it may sometimes be desired to remove free fatty acids, odors or other constituents of a volatile nature, by blowing the oil with live steam, under vacuum. This operation may follow the oxidation of tocopherol. It follows conventional steam refining techniques. To this end, the conduit 26 is provided with branch 26a, which may be vented to the atmosphere or a stack (not shown), but in the event that it is desired to close off this vent and to subject the chamber II] to vacuum, a 3- way valve 29 is provided which may be turned in such manner as to selectively connect the cone duit 26 to a source of vacuum (not shown) or vent it to the atmosphere.

The upper extremity of the chamber I0 may be closed by a head 32 which is secured in position by any appropriate means, such as head bolts 33 extending through the edge of the head, and a flange 34 about the upper edge of the chamber. For purposes of agitating a body of oil in the chamber, an electrical motor 36 is secured upon the head, preferably near the vertical axis thereof, and this motor is geared or connected by means (not shown) to a downwardly extending shaft 31 which is provided with one or'more agitator disks or blades 33 designed to subject the oil in the container to vigorous agitation or whipping, thus efiecting intimate contact between the oil and gases introduced therein, and also promoting uniform heating of the oil. The agitator can be dispensed with but is helpful. Agitation should not be so vigorous as to induce excessive foaming.

For purposes of introducing gases or vapors into the oil, a distributor head 39, having minute outlets (not shown) for gas or vapors, may be provided near the bottom of the chamber, and this head is connected by a conduit All to the head 32. The conduit, externally of the chamber, is pro- I vided with a valve 42 by means of which the flow of gases or vapors in the conduit may be con-. trolled at will. At its upper extremity, the conduit M is provided with a manifold 43 to which is connected a conduit Ml having a valve 36 and being designed for the introduction of air or oxygen into the manifold 43. A conduit 41," having a valve 48, is also connected to the manifold, and is designed for the introduction of steamjnto the conduit 4|.

In some instances, it is desirable to blow the oil with an inert gas, such as carbon dioxide, for purposes of removing readily volatile constituents, such as water absorbed in the oil, or volatile odorous constituents which may be present in or formed in the oil during the treatment. To this end, the manifold 43 is provided with a conduit 49 leading to, a source of gases, such as carbon dioxide, nitrogen, or preferably a reducing or non-oxidizing flue gas low in oxygen, such as the gases obtained in the composition of butane or the like. The conduit 49 is also provided with a valve 5| to control the rate of flow of gases therethrough, or to permit them to be turned off or on at will.

It will be apparent that by properly. opening or closing the valves 46, 48 and 5!, oxidizing gas, such as air, or steam or inert gas, can be caused to bubble upwardly through the distributor head 39, and the bubbles are efliciently broken up to very small sizes by the agitator blades 38, thus assuring thorough contact of the oil with the gaseous medium.

The head 32 is also shown as being provided with an inlet 53, having a funnel-like upper extremity 54, through which solid or liquid treating materials may be introduced into the container II). For example, pulverized absorbent agents, such as fullers earth, magnesium silicate, or acid treated clays, such as Filtrol (an acid activated clay) may be poured into the container through this opening. The opening may also be employed for the introduction of oxidation catalysts, notably carboxylic acid salts of the heavier metals, such as the naphthenates, oleates, linoleates or the like, salts of cobalt, maganese, lead or other metals which are employed as dryers to promote the hardening of films containing drying oils. In event that it is desirable to prevent the drawing of air into the chamber H), or to prevent vapors or gases from passing through the vent, a plug 56, preferably of frusto-conical vertical section, adapted to seat in funnel portion 54, is provided. Since superatmospheric pressures are not usually employed in the process, the weight of the plug is usually enough to hold it in place.

THE OIL The oils to be treated may comprise any of the common drying or semi-drying oils, such as linseed oil or soybean oil which may be too rich in tocopherol or other inhibitors for most satisfactory drying, and which may also contain pigments and/or objectional fatty acids, break, or the like. Extracts of high iodine value oil,.,such as soybean oil, which have been obtained by solvent fractionation with furfural or the like, in the manner taught by U. S. Patent 2,200,391, are especially suitable for the application of the technique since they are high in iodine value but often contain considerable color and inhibitors. Usually the break content is low, but it may not be completely absent. An appropriate oil for treatment will usually contain .1 to .3% or .4% by weight or more of tocopherol. It may also contain much less tocopherol, e. g. .03% by weight, but naturally, drying oils of such low inherent tocopherol content dry very will without oxidation treatment and the advantages of treating them are smaller.

THE ADSORBENTS.

, Pulverulent or granular adsorbent agents, such as fullers earth, magnesium silicates of the type described in U. S. Patents 2,076,545, 2,163,525, 2,163,526, 2,163,527, 2,434,418, 2,450,549, or acidactivated clay, such as Filtrol or Special Filtrol, which are acid activated clays, may be employed as adsorbent agents. These are introduced through the charging opening 53, or they may be introduced with the oil. It is also contemplated to employ activated charcoal or bone char, or the like. These usually are porous or cellular solid materials with very high specific surfaces adapted selectively to adsorb break, color, free fatty acids and the like.

Mixtures of adsorbents are contemplated. For example, fullers earth and acid activated clay may be employed. The acid activated clay is especially effective in promoting color removal. The acid activated clay could comprise 10% to by weight of the adsorbent mixture (fullers earth and acid activated clay).

' The amount of adsorbent required will vary 7. adsorbent and the. properties which are to be-obtained in the refined oil. Usually, preliminary tests for any given oil or adsorbent are required to assure optimum results. In general, the proportion of adsorbent will fall within a rangeof 0.25 to by weight, based upon the oil treated.

CONDITIONS OF OPERATION.

Treatment of the oil with the adsorbent agent may follow conventional modes. That is, it may be employed without the additional application of steam. However, the effectiveness of the adsorbent can often be increased by inclusion of steam treatment, in accordance with the disclosure of application Serial No. 41,168.

Assuming that steam is employed, the chamber lll should be charged with oil, which is at or is brought to the right temperature, e. g. about 210 to 250 F. Adsorbent agent is added and the agitator may be started and steam may be introduced through distributor 39. The temperature of the oil and steam, preferably, are soregulated that steam does not condense out as a definite water phase. However, it is desirable that the oil be maintained under hydrating conditions. For most efficient operation, the steam should be broken up into minute bubbles for purposes of obtaining thorough contact with the oil. The size of the bubbles, of course, can be controlled by regulating the rate of fiow of steam, the size and number of openings in the distributor head 39, also by the the speed of rotation of the agitator disks 38.

The steam may be introduced at substantially any desired rate, but it is suggested that a rate of approximately 0.005 to 0.20 pound of water as steam per minute per 100 lbs. of oil is satisfactory for most purposes. into the heated oil near the bottom of the container and at the same rate so that the water is immediately converted to live steam. and distributed as such through the remainder of the oil. The steam treatment is continued until the oil is appropriately decolorized and/or break is eliminated, after which the steaming operation is discontinued. A period of about minutes to 2 hours of steaming is satisfactory for most oils. If doubt exists as to the end point of any specific stage of treatment of an oil, samples can be drawn off at 25 and subjected to inspection or to qualitative or quantitative tests, such as color tests, e. g. Lovibond or Gardner, or acid values may be checked. The well-known test for break may also be conducted. In this, a few drops of hydrochloric acid are run into the sample and the latter is then heated to about 550 F. If any appreciable amount of break is present in the oil, it will separate as an observable precipitate.

If bleaching includes the steaming operation, the oil preferably is blown with an inert gas, such as carbon dioxide or a combustion gas, in order to expel water adsorbed or entrained in the oil. The drying should be continued until a sample of the oil will not assume a haze when cooled. About 15 or minutes is usually long enough, but longer is permissible. The operation can be conducted at a temperature of about 210 to 250 C.

REMOVING INHIBITORS For purposes of further treating the oil in order to remove or reducethe proportion of inhibitors of drying, such as tocopherol or vitamin E which may be in the oil, the oil which has been treatedwith'adsorbent agent, with or without steam, and

Water could also be pumped which still contains the spent or partially spent adsorbent immediately subjected to controlled air oxidation. If' the conditions of operation are correctly chosen, the tocopherol content can be reduced to a level at which it is not objectionable, without substantially changing the iodine value, the acid value, or the peroxide value of the oil.

The oxidation catalyst Anessential feature of controlled oxidation involves the introduction into the oil of a small amount of an oil-soluble catalyst of drying, such as a carboxylic acid salt of a heavy metal. Appropriate catalysts include the naphthenates, oleates, linoleates, resinates or the like of heavy metals, such as cobalt, nickel, chromium manganeseor lead. This type of catalyst is commonly introduced into paints and varnishes as a drier to promote the hardening of the films upon exposure to the atmosphere. These catalysts are a well recognized commodity and may be purchased already made up. Usually, the driers will be introduced as solutions in an appropriate organic solvent, such as painters naphtha or the like.

The proportion of catalyst should be within a range at which effective oxidation of tocopherol results, with a minimum oxidation of the oil to reduce iodine value or to form acids or peroxides. If the amount of catalyst is properly chosen, the reaction can be made highly selective for the tocopherol. In the case of the cobalt driers, the proportion should be .0005 to 002% of cobalt, upon a weight basis. The preferred range of cobalt is within the limits of .001 to .0015%, by weight, calculated as elemental cobalt. The amount of drier employed is less than that usually employed in paints. However the amount should be substantially larger than that employed in controlled oxidation selectively to remove inhibitors from oil free of adsorbents. If the concentration is too low, there-is a loss of selectivity in the oxidation.

Blowing with oxidizing gas After the catalyst is introduced and the oil has been heated to a temperature within a range of about 250 to 260 or 280 F., or approximately to these values, a measured stream of air is passed into the distributor 39 and is bubbled into the oil where it. is broken up into minute bubbles in order selectively to oxidize the inhibitors which maybe present. The rate of introduction for air is approximately such as to introduce .001 to .004 cubic foot of oxygen per minute per gallon of oil to be treated. Of course, if undiluted oxygen is employed, these will be the proportions employed. If air is employed, the volume of air will be approximately five times the above figures, since air is approximately oxygen, as determined upon. a volume basis. Usually, the total volume of air will be Within a range of about .2 to 2.5 cubic. feet per gallon of oil treated. However, air flow rates as high as one cubic foot per minute and a total flow of 15 cubic feet of air per gallon of oil are contemplated. Usually these high rates are not required except where the quantity of oil treated is small and/or the distribution of air in the oil is poor.

Blowing is continued until the content of inhibitors has been reduced to a desired figure, as determined by conventional chemical tests or analyses,.such as the Emmerie-Engel test. Ordinarily, the tocopherol content will be reduced to avalue below .1% by weight. Usually the tocopherol, content of the oil will: be reduced by 50 or even 98%. When sufficiently low values are attained, the residual tocopherol ceases substantially to slow up the air drying of the treated oil. Usually, satisfactory reduction of tocopherol content will be attained in 10 to 90 minutes.

The conditions of operation in the treatment of a drying or a semi-drying glyceride oil under the provisions of the present invention may be roughly summarized as follows:

The glyceride oil will usually be of an iodine value of 130 or above, may be either break-positive or break-negative as determined by Al O. C. S. test Ca 10-40, will contain enough tocopherol to have a rate of drying slower than could be expected from the iodine value of the oil. It may also be of objectionable color and relatively high fatty acid content since these values are also improved by application of the present technique.

STEPS OF TREATMENT A. Treatment with adsorbent Adsorbent-.5 to by weight based upon the oil treated.

Temperature of oil treated2l0 to 240 or 250 F.

Time of treatment15 to 120 minutes.

Steaming during treatment with adsorbent is optional. If it is employed, the total amonut of steam will be: 1 lb. to lbs. per 100 lbs of-oil.

Pressure of treatmentat or near atmospheric.

B. Selective oxidation Drying catalyst.0001% to'.002% by weight as metallic content based upon the oil treated. Temperature of oil in treatment-250 to 260 F.

or slightly more or less.

Volume of oxygen per minute per gallon of oil- .001 to .004 cu. it.

Time of treatment-10 to 90 minutes.

Pressure of treatment-at or near atmospheric.

If steam is employed in stage A, the oil may be dried with inert gas between stages to remove any traces of moisture which may be absorbed in the oil in the steaming operation. This step may not always be required. The presence of moisture in the oil can be checked by drawing off a sample, filtering it and observing if a haze or cloud is formed when the oil is cooled.

The oil, after the blowing operation involved in step B, may be further blown with inert gas such as nitrogen or carbon dioxide to sweep out any odors due to oxidation. This step also is optional.

C. Filtration to remove absorbent The oxidized oil, low in tocopherol and color as obtained in step B, subsequently is drawn off and subjected to an appropriate filtering or centrifuging operation or other treatment to eifect separation of the absorbent agent employed to decolorize the oil in step A. The absorbent thus separated from the oil can be extracted with naphtha or other agent to recover oil and perhaps other constituents which may be entrained therein.

As a result of the application of the foregoing techniques, oils which are of good color, low inhibitor content, of low peroxide content, and low in free fatty acids, can readily be obtained. The process is especially well adapted for the treatment of extracted fractions such as soybean oil as obtained by the treatment of the oil with a polar solvent such as furfural in the manner disclosed in U. S. Patent 2,200,391.

tioned U. S. Patent 2,200,391. This oil contained a small amount of break, though less than that which would normally occur in the raw unextracted oil. The oil was of relatively high iodine value but still dried rather slowly as shown in the subsequent table.

This oil was bleached with adsorbent agent in the presence of live steam as follows:

An appropriate container was charged with 2000 parts by weight of the extract oil and 40 parts (2% by weight) of an appropriate absorbent as herein described. The specific absorbent of theexample was a commercially available product termed Special Filtrol. It is understood-to be an acid-activated clay. The mixture of oil and absorbent was heated to a temperature in the range of 212 to 230 F. inclusive and was blown with live steam for 45 minutes while this temperature wasmaintained. During the blowing operation, vigorous agitation was maintained and steam was delivered at a rate of about .008 lb. per minute per gallon of oil.

The end point of the treatment was determined by drawing off small samples of oil and subjecting them to the conventional Gardner color tests.

The oil, when sufiiciently low in color and break and while still in the original container and while it still contained the absorbent, was subjected to drying by blowing it gently with inert gas, such as a mixture of nitrogen and carbon dioxide as obtained from combustion gases at a temperature within a range of 260 to 265 F. until the oil would no longer give a test for water when a sample was subjected to cooling. In the specific example, the oil was found to be free of moisture within 20 minutes. At the end of the drying operation the temperature of the oil was 263 F.

The mixture of oil and absorbent in the container was now ready for the controlled oxidation of the tocopherol or other inhibitors contained therein. For this purpose .5- part by weight of a drier, which was a solution of cobalt naphthenate containing 6% of active metal calculated as cobalt, was introduced. The cobalt constituted 0.0015 percent by weight based upon the oil treated.

The agitator was then started and air was bubbled into the hot catalyzed oil mixture at atmospheric pressure and at a rate of .01 cu. ft. per minute per gallon of oil. During this time the temperature was maintained within a range of 260 to 265 F. The progress of the reduction of the tocopherol or inhibitor content of the oil was followed by Y conventional Emmerie-Engel tests conducted upon samples drawn off at an,-

propriate intervals. At the end of 45 minutes of air passage it was deemed that the tocopherol content was reduced to an adequately low level, the tocopherol content being 032%. It was observed that the oil had an odor of oxidation produced which was deemed to be objectionable. In order to eliminate this odor or to reduce it to a satisfactory low level, the hot oil was again treated with a gentle stream of inert gas such as nitrogen and carbon dioxide mixture in order to blow out the undesirable constituents. Only a few minutes were required for this operation and its satisfactory completion could be determined organoleptically.

The oil was thendrawn off and filtered. The product, when cooled, was of highly satisfactory properties. high in iodine value. It was also break negative. Samples of this product were formulated into coating compositions whichxwere checked against similar formulations of the oil before treatment for purposes f .determining the improvements of properties obtained by the treatment. The results of these tests are tabulated as follows:

Before After Iodine value 151.6 150.3 I Tocopherol (by weight) 28% 0.032% Tocopherol destruction 88.6 Peroxide value .8 1.3 Gardner color 14.0 9.0 Drying time over 24 hrs. 6.5 Drop in iodine value 0.8%

Drying time was determined by a vstandard test m which the two oils were formulated with identical pigmerits and driers,'and were thenspread as films upon glass panels and dried and the time of drying was noted. The treated soybean oil extract dries almost as well as linseed oil.

Example 2.It is also contemplated to substitute a synthetic magnesium silicate having adsorptive properties for Special Filtrol. The condition of operation described in the previous example may be followed in all respects, with the magnesium silicate replacing Special Filtrol. Such treatment will successfully accomplish the objects of the invention in all respects, except that with equal percentages of adsorbent, better color is obtained in the bleached product through the use of Special Filtrol."

Example 3.In like manner it is contemplated to substitute fuller earth for Special Filtrol.

The conditions of operation described in Example 1 may again be followed in all respects with the fullers earth replacing Special Filtrol. Such treatment will again accomplish the objects of the invention in all respects except that the use of Special Filtrol results 'in a bleached product of better color.

The following example demonstrates the use of the present invention in which the bleach cycle of the operation i 'conducted as a conventional dry'bleach with an'acid-ac'tivated clay. For purposes of comparison the results on the same oil, usingthe same percentage of adsorbent but in a steam-bleach cycle are given. These results indicate that a dry-bleach in the conventional manner is quite satisfactory, although the use of the steam-bleaching technique does give more color improvement and a somewhat more selective subsequent oxidation of the inhibitors.

Example 4.-In this example 1,000 parts by weight of a soya extract oil, obtained by countercurrent selective fractionation of soya oil, was heated to 220 F. in the presence of 18.7 parts by weight of an acid-activated clay (i. e., Special Filtrol). The temperature was held at 220 F. while the mixture was well agitated for 45 minutes. At this point the temperature was raised to 265 F., sufiicient cobalt naphthenate solution was added to give a cobalt metal concentration of .0013% by weight of the charge and a flow of air was introduced. The air was welldispersed throughout the mixture by virtue of the good agitation provided and by having the air introduced through an air distributor. The

air was passed through the oil at a basic how It was low in free fatty acids and 1 rate of 0.6 cubic foot per minute per :gallonof oil for 20 minutes. The total air :pa-ssed was 12 cubic feet per gallon of oil treated. At the end of this time the air flow was discontinued and-a minimum flow of an inert gas, in the range 'of 0.1 cubic foot per minute was passed through the oil for 15 minutes to eliminate oxidative odors. The oil-adsorbent mixture was then filtered and analyzed.

In a companion run, the above conditions were exactly duplicated in all respects with the exception that a flow of live steam was passed through the oil for the 45 minute period at 220 F. The steaming rate was 065% by weight of oil charge per minute. The table below indicates the results obtained.

The treated oil in each case was satisfactorily low in inhibitor content and dried to touch in 5.5 hours by the drying test previously discussed. It can be seen that while both treatment are satisfactory, the bleaching with the aid of steam gave a somewhat lighter color.

Example 5.-The following illustrates the use of the reversed sequence of steps, wherein a selective oxidation is first applied, followed by a bleaching with the aid of steam. The oil used, as well as the equipment were identical with that in the previous example.

1000 parts by weight of the oil was subjected to the action of air dispersed and passed through the oil at a temperature of -265'F. in the presence of 18.7 parts by Weight of Special Filtrol. The air flow rate was again 0.6 cubicfeet per minute per gallon of oil for 20 minutes. The catalyst used was cobalt naphthenate at a concentration-of 0.0013% cobalt (as metal) byweight. At the end of the 20 minutes the air flow was discontinued, the temperature was reduced to 220 F. and live steam was passed through the charge for a period of 45 minutes at a'rate of approximately 0.065% by weight per minute. At that time the steam flow was discontinued and an inert gas flow was used for 15 minutes to eliminate o'xidative odors. The mixture of oil and adsorbent was'then filtered and analyzed. The table indicates results "obtained.

The treated oil in this case showed little oxidative efiectsin that onlya small amount-of the inhibitor was oxidized and the drying 'rate of the oil as a film was not-satisfactory. The color obtained by bleaching was not as light as that 'obtained in the previous examples. Ihisillus'trates that a reversed sequence of operations is entirely unsatisfactory and that an integral part of the invention is the use of the proper sequence of treatments.

Example 6.The following illustrates the use of simultaneous bleaching and oxidation incontrast to the step-wise sequence previously illustrated. The same soya extract oil was used.

1000 parts by weight of oil were heated to 265 F., 18.7 parts by weight of Special Filtrol was added, a cobalt naphthenate solution was added to give a cobalt metal concentration of 0.0013% by weight, and simultaneously live steam and air were passed through the mixture. The air rate was again at 0.6cubic foot per minute per .gallon of oil, and the steam rate was the same as previously used. After twenty minutes the air; flow was discontinued, but the steam flow was maintained until the mixture had been steamed for 45 minutes. At this point the steam flow was discontinued and an inert gas flow maintained for 15 minutes to eliminate oxidative odors as well as to assist in water removal. The oil was then filtered and analyzed. The results obtained are indicated in the table below.

Original Treated Oil Oil Iodine Value 152. 4 151. 9 Gardner Color. l3. 10. 5 Acid Value 0.8 1.5 Peroxide Value 0.5 2. 4 Tocopherol Content, Per Cent- 0.35 0.26 Tocoplierol Destruction, Per Gen 25. 7 Iodine Value Decrease, Per Cent 0. 3

The treated oil in this case likewise showed little selective oxidation eifects and retained the majority of the active inhibitor. The drying rate of the oil as a film was unsatisfactory. The simultaneous bleaching and oxidation are shown to be ineifective and again demonstrate the integral part of the invention is the proper sequence of treatment within specified ranges of conditions.

The forms of the invention as herein described are given by way of example rather than limita- .tion. It will be apparent to those skilled in the thereafter vigorously subjecting the oil containing the adsorbent agent and .0001 to .002% by Weight of active drier metal, to contact with a gas containing free oxygen, selectively to remove tocopherol from the oil, discontinuing the treatment of the oil with the gas before the iodine value of the oil is materially reduced and removing the adsorbent agent.

2. In a process of treating a drying glyceride oil which contains coloring matter and which also contains inhibitors of air drying in anamount objectionably to retard drying, the steps of blowing the oil with live steam in the presence of a dispersed adsorbent agent until the color is improved, then adding to the oil containing the adsorbent .0001 to .002% by weight of a heavy metal in the form of a carboxylic acid salt, which salt is soluble in the oil and is a catalyst of air drying of the oil, blowing the oil with an oxygencontaining gas at a rate to introduce .001 to .2 cubic foot of oxygen per gallon of oil per minute until 50 to 98% of the inhibitor content of the oil is eliminated without appreciably changing the peroxide value and the iodine value of the oil and subsequently filtering the oil to remove the adsorbent agent therefrom, whereby to obtain as a product, oil which is relatively low in color and of relatively low inhibitor content.

3. In a process of treating drying glyceride oil containing objectionable amounts of color constituents and inhibitors of drying, whereby to reduce the content of the oil in such color constituents and inhibitors without substantial change in the iodine value and peroxide value, the steps of adding to the oil an acid activated clay and contacting the dried mixture at a temperature to effect adsorption of coloring matter and agitating the oil at said temperature until coloring matter is adsorbed and substantial improvement of the color of the oil is eiTected, then adding to the bleached oil containing the adsorbent .0001 to .002% by weight of cobalt in the form of a carboxylic acid salt which is a catalyst of air drying of the oil and is soluble in the oil and blowing the oil with gas containing free oxygen at a rate to introduce .001 to .2 cubic foot of oxygen per gallon of oil per minute for a period of 10 to minutes, then discontinuing the blowing operation and filtering the oil to obtain a product which is relatively low in color and from which 50 to 98% of the inhibitors of drying have been eliminated.

4. In a process of treating drying glyceride oil containing objectionable amounts of color constituents characterizing a glyceride oil and inhibitors of drying, whereby to reduce the content of the oil in such color constituents and inhibitors without substantial change in the iodine value and peroxide value of the oil, the steps of dispersing in the oil .5 to 5% by weight of an adsorbent agent, blowing the oil with live steam until the desired color is attained, then adding to the oil containing the spent adsorbent agent .0001 to .001% by weight of cobalt in the form of a carboxylic acid salt which is a catalyst of air drying of the oil and is soluble in the oil, blowing the oil with gas containing free oxygen at a rate to introduce .001 to .2 cubic foot of oxygen per gallon of oil per minute for a period of 10 to 90 minutes, then discontinuing the blowing operation and filtering the oil to obtain a product which is of improved color and from which 50 to 98% of the inhibitors of drying have been eliminated.

5. In a process of treating drying glyceride oil containing objectionable amounts of color constituents characterizing a glyceride oil and inhibitors of drying whereby to reduce the content of the oil in such color constituents and inhibitors without substantial change in the iodine value and peroxide value of the oil, the steps of dispersing in the oil an adsorbent magnesium silicate, blowing the oil with live steam until the desired color is attained, then adding to the oil containing the adsorbent .0001 to .002% by weight of cobalt in the form of a carboxylic acid salt which is a catalyst of air drying of the oil and is soluble in the oil and blowing the oil with gas containing free oxygen at a rate to introduce .001 to .2 cubic foot of oxygen per gallon of oil per minute for a period of 10 to 90 minutes, then discontinuing the blowing operation and filtering 15 the oil to obtain a product which is of improved color and from which 50 to 98% of the inhibitors of drying have been eliminated.

6. In a process of treatingdrying glyceride oil containing objectionable amounts of color constituents and inhibitors of drying, whereby .to reduce the content of the oil in such color constituents and inhibitors without .substantial change in the iodine value and peroxide value of the oil, the steps of agitating a mixture of the oil and an adsorbent earth at a temperature at which color constituents are adsorbed to efiect substantial improvement in the color of the oil, then adding to the oil containing the adsorbent earth .0001 to .002% by weight of cobalt in the form of a carboxylic acid salt which is a catalyst of air drying of the oil and is soluble in the oil and blowing the oil with gas containing free oxygen at a rate to introduce .001 to .2 cubic foot of oxygen per gallon of oil per minute for a period of to 90 minutes, then discontinuing the blowing operation and filtering the oil to obtain a product which is of improved color and from which 50 to 98% of the inhibitors of drying have been eliminated.

'7. In a process of treating soybean oil containing objectionable amounts of color constituents and. inhibitors of drying, whereby to reduce the content of the oil in such color constituents and inhibitors of drying without substantial change in the iodine value and peroxide value of the oil, the steps of agitating for an effective period of time a mixture of the oil and an acid activated clay at a temperature at which color constituents are adsorbed to effect substantial improvement in the color of the oil, then adding to the oil containing the clay .0001 to .002% by weight of a drier metal in the form of a carboxylic acid salt which is a catalyst of air drying of the oil and is soluble in the oil, blowing the oil with gas containing free oxygen at a rate to introduce .001 to .004 cubic foot of oxygen per gallon of oil per minute for a period of 10 to 90 minutes, then discontinuing the blowing operation and removing the clay from the oil to obtain a product which is of improved color and from which 50 to 98% of the inhibitors of drying have been eliminated.

8. In a process of treating soybean oil which is the extract product obtained by contacting soybean oil with a polar solvent to fractionate the oil upon the basis of the degree of unsaturation, and evaporating the polar solvent, said oil containing objectionable amounts of color constituents and inhibitors of drying, whereby to reduce the content thereof in the oil without substantially changing the iodine value and peroxide value or the oil; the steps of agitating for an eii ective period of time a mixture of the oil and a comminuted adsorbent agent, the mixture being at a temperature at which coloring constituents are adsorbed to effect substantial improvement in the color of the oil, then adding to the oil containing the adsorbent .0001 to .002% by weight of cobalt in the form of a carboxylic acid salt which is a catalyst of air drying of the oil and blowing the oil with gas containing free oxygen at a rate to introduce .001 to .2 cubic foot of oxygen per gallon of oil per minute for a period of 10 to 90 minutes, then discontinuing'the blowing operation and filtering the oil to obtain a product which is of improved color and from which 50 to 98% of the inhibitors of drying have been eliminated.

9. The step as defined in claim 8 in which the adsorbent agent is an adsorbent earth which is employedin a proportion of .5 to 5% by weight based upon the oil treated.

10. The steps as defined in claim 8 in which the adsorbent agent is adsorbent magnesium silicate ina proportion of .5 to 5% by weight based upon the oil treated.

11. The steps as defined in claim 8 in which the adsorbent agent is acid-activated clay.

12. In a process of treating a drying glyceride oil containing objectionable amounts of color and inhibitors of drying, the steps of adding to the oil .5 to 5% of an adsorbent agent for color constituents, contacting the mixture for an effective period of time and at a temperature to adsorb color to efiect substantial improvement in the color of the oil, then adding to the bleached oil containing adsorbent agent a heavy metal which is a catalyst of air drying of the oil, said metal being in the form of a carboxylic acid saltwhich is soluble in the oil, blowing the oil at a temperature of about 240 to 270 F. and for a period'of about 10 to minutes with a gas containing free oxygen, and at a rate to introduce .001 to .2 I

cubic foot of oxygen gas per minute per gallon of oil treated, the salt of the heavy metal being employed in an amount selectively to effect oxidation of the inhibitors by the oxygen without substantially lowering the iodine value of the oil, then at the conclusion of the blowing operation, removing the spent adsorbent to produce an oil product which is of improved color and low in inhibitor content.

13. In a process of treating a drying glyceride oil containing objectionable amounts of color and inhibitors of drying to improve these characteristics, the steps of adding to the oil .5 to 5% of adsorbent agent, blowing the oil at a temperature of 212 to 240 F. with live steam to eliminate break and improve color adding to the oil containing the spent adsorbent .0001 to .002% by weight of a heavy metal which is a catalyst of air drying of the oil in the form of a carboxylic acid salt which is soluble in the oil, then blowing the oil at a temperature of about 240 to 270 F. and for a period of about 10 to 90 minutes with a gas containing free oxygen at a rate to introduce .001 to .2 cubic foot of oxygen per minute per gallon of oil whereby selectively to oxidize inhibitors in the oil without substantially lowering the iodine value of the oil, then at the conclusion of the blowing operation removing the spent adsorbent to provide an oil product which is of improved color and low in inhibitor content.

14. In a process of treating a drying glyceride oil obtained as an extract product by contacting soybean oil with a. polar solvent selectively to remove relatively highly unsaturated glycerides and then evaporating the polar solvent toprovide said extract product, the steps of adding to the oil .5 to 5% of an adsorbent agent for break and coloring matter in the oil, blowing the oil at a temperature of 212 to 240 F. with live steam to eliminate break and to remove coloring matter, then adding to the oil containing the spent adsorbent .0001 to .002% by weight of aheavy metal which is a catalyst of air drying of the oil, the metal being in the form of a carboxylic acid salt which is soluble in the oil and then blowing the oil at a temperature of about 240 to 270 F. and for a period of about 10 to 90 minutes with gas containing free oxygen at a rate to introduce .001 to .004 cubic foot of oxygen per minute per gallon of oil, then removing the spent adsorbent to provide a product of good color and relatively low in inhibitor content.

15. The steps as defined in claim 14 in which 2 the catalyst metal is cobalt.

16. The steps as defined in claim 14 in which 5 the adsorbent agent comprises acid-activated Number clay. 3,865 17. The steps as defined in claim 12 in which 7 7 4 the adsorbent agent is acid-activated clay. 577 7 HENRY A. VOGEL. 10

REFERENCES CITED The following references are of record in the file 01' this patent:

18 UNITED STATES PATENTS Name Date Hodgins Apr. 9, 1940 FOREIGN PATENTS Country Date Great Britain Feb. 1914 Great Britain Sept. 1914 Great Britain June 4, 1944 OTHER REFERENCES Bailey: Industrial Oil and Fat Products, pages 383-387, Interscience Publishers Inc., N. Y., 1945.

Claims

1. IN A PROCESS OF TREATING AN UNSATURATED GLYCERIDE OIL OF A CLASS CONSISTING OF DRYING AND SEMI-DRYING OILS, SAID OILS CONTAINING OBJECTIONABLE AMOUNTS OF COLORING MATTER AND TOCOPHEROL, THE STEPS OF ADDING AN ADSORBENT AGENT FOR COLORING MATTER TO THE OIL, EFFECTING ADSORPTION OF COLORING MATTER BY THE ADSORBENT AGENT TO EFFECT SUBSTANTIAL IMPROVEMENT IN THE COLOR OF THE OIL, THEREAFTER VIGOROUSLY SUBJECTING THE OIL CONTAINING THE ADSORBENT AGENT AND .0001 TO .002% BY WEIGHT OF ACTIVE DRIER METAL, TO CONTACT WITH A GAS CONTAINING FREE OXYGEN, SELECTIVELY TO REMOVE TOCOPHEROL FROM THE OIL, DISCONTINUING THE TREATMENT OF THE OIL WITH THE GAS BEFORE THE IODINE VALUE OF THE OIL IS MATERIALLY REDUCED AND REMOVING THE ADSORBENT AGENT.