US3895042A - Clay-heat refining process - Google Patents

Abstract

Crude fatty substances, including edible and inedible fats and oils and free fatty acids, are refined by heat treatment in the temperature range of about 250*-500*F in the presence of a bleaching adsorbent or in the presence of phosphoric acid and a bleaching adsorbent. This refining can be used in lieu of the conventional alkali-refining of fats and oils.

Description

United States Patent Taylor July 15, 1975 [54] CLAY-HEAT REFINING PROCESS l.973,790 9/1934 Appleton 260/424 2.110.789 3 1938 Cl t t l. 260 428 [75] Inventor: Frederick Taylor Credlt 2,413,009 12i1946 260i424 Canada 2,602,807 7/1952 Morris et al. 260/424 2,783,260 2/1957 Merker 260/424 [73] Assgnee' 5:22? Packers TOmmo 2.795.543 6/1957 Opie 260/424 8 3,284,213 11/1966 Van Akkeren 260/424 [22] Filed: Apr. 11,1974

Primary Examiner-Winston A. Douglas [21] Appl 459958 Assistant ExaminerPaul E. Konopka Related US. Application Data Attorney, Agent, or Firm-Bacon & Thomas [63] Continuation of Ser. No. 877,424, Nov. 17, 1969,

abandoned [5 7] ABSTRACT Crude fatty substances, including edible and inedible [52] US. Cl. 260/424; 260/419; 260/428 fats and oils and free fatty acids, are refined by heat [51] Int. Cl.'.... CllB 3/04; Cl 1C 1/08; Cl 1B 3/00 treatment in the temperature range of about [58] Field of Search 260/419, 423, 424, 429 250500F in the presence of a bleaching adsorbent or in the presence of phosphoric acid and a bleaching [56] References Cited adsorbent. This refining can be used in lieu of the conventional alkali-refining of fats and oils.

8 Claims, No Drawings CLAY-HEAT REFINING PROCESS This is a continuation, of application Ser. No. 877,424, filed Nov. 17, 1969 now abandoned.

BACKGROUND OF THE INVENTION This invention relates to the refining of crude fatty substances. such as. unrefined free fatty acids, fatty oils and fats, by the use of heat treatment of the fatty substances in the presence of a bleaching adsorbent and preferably also in the presence of a small amount of phosphoric acid. This process may be used in lieu of conventionalalkali refining. It is applicable to the treatment of edible oils and fats for the production of margarine, shortening, salad and cooking oils, coating fats, etc..as well as for treatment of inedible products such as inedible tallow, fatty acids, and oils for the paint and resin industry. It may be combined with conventional bleaching and deodorizing operations and is adapted for combination with hydrogenation processes.

The processes most widely used for the refining of fats and oilsat present are the well known alkali refining pr'ocesSesLAcid refining operations have been proposed but have not been favorably received by the industry. In alkali refining the free fatty acids are conve'rt'ed' to soaps which are eventually removed from the oil in a water phase. The recovered oil is then bleached with an adsorbent, filtered and deodorized either before or after hydrogenation.

There are several disadvantages involved in the use ofalkali refining. First of all there are the expensive installation costs of the equipment, particularly the centrifuges in which the aqueous phase is separated from theoil. Then there are other centrifuges in which the oil is washed with water to remove residual alkali and soap. These centrifuges run continuously and at times provide quite a maintenance problem. Another serious disadvantage of'alkali refining is the seemingly inevitable amount of saponification of the oil by the action of the alkali, resulting in decreased oil yields.

BRIEF SUMMARY OF THE INVENTION The present invention provides a process for the refining of crude fatty substances without the use of alkali. The crude fatty substance is contacted with an ad sorbent, which is preferably an acid-activated clay, at a temperature in the range of about 250F to 500F in the substantial absence of air, for a short time. This step is improved by carrying out the heat treatment process in the presence of a small amount of phosphoric acid, which has the effect of lowering the temperature of treatment and improving the quality of the product. After this treatment the adsorbent and impurities adsorbed thereon are removed by filtration. Treated oils and fats can be deodorized directly or hydrogenated prior to deodorization. Alternatively, a mixture of oil, adsorbent and acid without filtration and after addition of a suitable catalyst can be hydrogenated directly; the clay with adsorbent impurities and spent catalyst are then filtered off. and the filtered oil is finally deodorized. In the course of these deodorizations the volatiles including the free fatty acids are removed from the oil.

DETAILED DESCRIPTION The process of the invention may be applied to a wide variety of oils including most of the usual edible oils and fats of commerce. The process can also be applied to inedible fatty materials such as inedible tallow,

fatty acids and crude oils for the paint industry. The fatty substances which have been-successfully treated by the process include soybean oil-, rapeseed oil. marine oil, sunflower seed oil, peanut oil, palmoihpalm kernel oil, cocoanut oil, lard, inedible talloweand oleic acid.

Any of the commercial bleachingadsorbents may be used in the process but it has been found that the bleaching'clays and especially acid-activatedbleaching clays '(e.g. Special-Filtrol) are significantly better than the other bleaching adsorbents. It has further been found that the acid-activated bleaching'clay may be used either in freshly prepared form or in the form of a spent activated clay from other oil refineryprocesses. The clay is preferably used in an amount in the range of from about 0.1 to about 6% by weight based on the weight of the oil, depending upon the nature of the oil being processed. Thus, a relatively clean oil, such as palm kernel oil, may require only about 0.] percent ad sorbent, whereas corn oil may require, for example,

about 6 percent. A small amount of filter aid, such as diatomaceous earth, may be added with the adsorbent to facilitate the eventual filtration. This is usually less than about 1.0 percent by weight based on the weight of the oil with 0.5 percent being quite satisfactory. Diatomaceous earths have no adsorbent properties and are used solely for improving filtration. Where the adsorbent is used without pre-addition of phosphoric acid the temperature of treatment is usually in the range of from about 400-500F. Satisfactory treatment of edible oils with acid-activated clay alone has been attained at about 45()F.

The phosphoric acid is employed in an amount which may vary from about 0.1 percent to L0 percent. Again, the amount of phosphoric acid depends to some extent upon the nature of the oil being treated. The amount of phosphoric acid also depends to some extent upon the temperature at which the oil is to be processed. Lower treating temperatures can be used where more phosphoric acid is used in the pre-treatment stage. The preferred temperature at which the oil is heated in the presence of the adsorbent clay is about 325350F where a pre-treatment with about 0.1 percent H PO has been carried out. The phosphoric acid may be mixed with the oil or fat at any temperature at which the oil or fat is in liquid condition. Preferably a short pre-treatment of the oil or fat with phosphoric acid is effected by agitating the acid with the oil or fat at a temperature ranging from about room temperature to about F following which the adsorbent clay is added and the mixture of oil, acid and adsorbent is then heated to a temperature in the desired higher range. The pretreatment of the oil with phosphoric acid at the relatively low temperature prevents foaming during heating of the oil.

The time of the treatment is relatively short. normally requiring only that the fatty substance be thoroughly contacted with the treating agent at the maximum temperature involved. Where bleaching adsorbent is used alone it may be added to the fatty substance prior to heating and the fatty substance and adsorbent are then heated together, under vacuum or inert atmosphere, to the maximum temperature. e.g. 450F, followed by immediate cooling and filtering. ltwill be understood, however, that the adsorbentcan' also the added to preheated fatty substance or to the fatty substance at any heating stage. Where phosphoric acid is employed it is preferred that it be added at relatively low temperature as described above and contacted with the fatty substance for a short period of time, e.g. about l to'30 minutes prior-to adding the adsorbent and heating to maximum treating temperature. Alternatively the phos: phoric acid and adsorbent may be added together to the oil prior to heating or at any heating stage.

The use of vacuum during the heating is ordinarily for the purpose of excluding air. However, the process may be combined with steam stripping while drawing a vacuum so as to remove free fatty acids and other volatiles. Alternatively, the heat treatment can be conducted under an atmosphere of inert gas, e.g. nitrogen.

REPRESENTATIVE EXAMPLES EXAMPLES 111 from a Zeiss refractive index of 79.3 to 62.3'in 40 min- Various crude fatty substances which normally would Both test results denote Satisfactory,pelfrmance' be processed by alkali-refining were subjected to combined phosphoric acid and acid-activated clay heat EXAMPLE 13 treatment. A 1,000 gram sample of each crude oil was placed in a 2,000 ml. threeneck distillation flask fitted with. a thermometer, a variable speed agitator and a An 18,500 lb. batch of crude soybean oil (FFA 033 glass tube connected to a nitrogen supply. The oil was percent) was run into a batch hydrogenation vessel of heated to 100F. The phosphoric acid was pipetted into the type used in the edible oil industry. 35 Lbs..of conthe flask,then the oil-acid mixture stirred'at slow speed centrated H PO, (0.19 percent) was added at 100F for 15 minutes. The adsorbent (Special-Filtrol) and filand the oil and acid were agitated at this temperature ter-aid (Celite) were added and a stream of nitrogen for 20 minutes at atmospheric pressure..300 Lbs. (1.6 started into the flask to exclude air and carry-off moispercent) of acid-activated clay (Special-Filtrol No. 4) ture released during heating. Heat was applied until the was added and the mixture heated to 345F under a desired treatment temperature was reached. Also, the vacuum (6-l2 inches Hg absolute pressure) with 30 upper portion of the flask was kept warm to prevent minutes heating time from 325F to 345F. A sample of moisture condensation. As soon as the desired reaction the oil at this point showed a colour of 0.4 R/SY and temperature was reached, the heating was stopped and a free fatty acid content (FFA) of 0.66 percent. Hydrothe flask cooled to 230F. The oils were filtered at this genation catalyst was then added to the batch of oil at temperature through a Buchner funnel. 345F and the oil was hydrogenated directly in the The clay-heat refined oils were analysed for color, presence of the refining agents and catalyst. The hydro- FFA, and loss and then deodorized under conventional genated oil (R1 60C 1.4561 was cooled to 210F, filconditions. Table 1 lists the results for each oil. tered bleached and deodorized. to provide a product oil TABLE 1 cent) was placed in a closed vessel which was equipped with steam and water coils, electric booster heater, agitator and ejector for drawing vacuum. 200 Grams of phosphoric acid was added to the oil and the mixture was agitated for 30 minutes at room temperature (80F). 8 Lb. of activated clay (Special Filtrol No. 4) and 2 lb. of filter-aid (Celite No. 545) were added, the vessel closed and a vacuum to about 19 inches Hg abs. pressure drawn. The batch was heated to the reaction temperature (from 80F to 350F) in minutes. Without hold-up time at 350F, the batch was cooled to 230F and the clay and filter-aid removed using a plate and frame filter. Laboratory deodorizing produced bland oil; also, the clay-heat refined oil hydrogenated H P0,,-CLAY-HEAT REFlNlNG OF A VARIETY OF CRUDE OILS Examples of Crude Fatty Substances Expeller Sun- Palm Palm Dry Rened- Analyses Soybean Rapeseed flower Com Peanut Palm Coconut Kernel l Kernel 11 Seal ered Lard Crude FFA 0.30 0.31 0.28 2.35 1.07 3.55 1.23 5.60 6.40 1.46 0.34 Treatment:

Active Clay 2.0 4.0 1.5 6.0 4.0 4.0 2.0 0.1 2.0 4.0 2.0 Filter-Aid 0.5 1.0 0.4 1.5 1.0 1.0 0.5 0.025 0.5 1.0 0.5 Phosphoric Acid 0.1 0.4 0.2 1.0 0.2 0.4 0.1 0.02 0.1 0.2 0.3

Temperature (F) 350 350 350 350 350 350 350 350 350 350 350 Treated Oil Color (Red) 1.0 1.3 0.4 2.0 0.9 1.4 0.4 1.2*** 0.7 0.5 FFA ("/z) 0.73 0.36 0.45 2.67 1.28 3.89 1.53 5.7 7.3 0.48 DeudmClzed Rd 07 10 04 20 07 17 07 05 07 13 06 0'1 01 r e FFA o 0.03 0.02 0.02 0.03 0.02 0.03 0.02 0.03 0.03 0.03 0.03 Flavour Bland Good Bland Bland Bland Bland Bland Bland Bland Bland Bland AOM (hr) 6 18 9 13 18 60 60 60 25 4 Schaal (days) 1 l 12 15 8 17 15 30 ll 20 8 5 Directly hydrogenated to 76 1V Crude oil colour very poor (9.0R) Bleached with 0.5% clay to obtain 11 color below 10R The clay-heat treatment satisfactorily refined all of a quality substantially equivalent to that obtained by types of crude oil listed in Table 1. Deodorized oil color, FFA, flavour, and stability, measured by AOM and Schaal-oven,indicated that these oils are equal to oil produced using caustic refining.

. TEXAMPLE 12 A 400 lb. batch of crude soybean oil (FFA-0.30 percaustic refining, hydrogenating, bleaching and deodorizing.

EXAMPLE 14 Samples of crude and caustic refined soybean oil were obtained during a plant alkali-refining operation. The crude sample was subjected to H PO -elay-heat re- TABLE II /2 inches) of l5Yl.0R and a FAC colour of l and was suitable for use as a toilet soap base. The H PO c1ayheat refining had far greater colour removal power than the normal bleaching process.

EXAMPLE 17 Three samples of a No. 2 inedible tallow were obtained. This crude material had an FAC colour of 31 and a FFA of 20.0 percent. The samples were subjected to H PO -clay-heat refining with different amounts of Caustic Refining Clay-Heat Refining Comparison Plant Caustic Refined Oil Refined H PO clay-Heat Crude and Refined Oil Analysis Oil Refined Bleached Deodorizcd Refined Deodorized Free Fatty Acid 0.68% 0.03% 0.04% 0.02% 0.90% 0.02% Color (Lovibond) 9.5R 1.8R 0.6R l.lR 0.8R Peroxide Value mc/kg 3.0 3.5 2.0 Nil Nil Nil AOM (70 mc/kg) Stability 6 hr 6 hr 10 hr 12% hr 12 hr Schaal Oven Stability l4 days 13 days Brown Bottle Stability 5 weeks 7 weeks Tucopherols 0.147574 0.138471 0.12557r 0.05057: 0.136171 0.091471 Frec Phosphoric Acid Nil Nil Nil Nil tracc Nil Conjugation E-Valuc at 233 mp. 3.1 2.9 3.0 7.0 5.3 9.6 E-Valuc at 268 mp. 0.3l 0.26 1.7 1.5 2.0 1.7 Conj Dicne (71) 0 0 0 0.58 0 0.81 Conj Trienc (7:) 0.003 0.002 0.043 0 0.054 0 From Table I] it will be seen that the product oils from the two refining processes were of substantially equal quality.

EXAMPLE 15 Crude soybean oil was heated to approximately 350F in the presence of 2% of acid-activated clay (Special Filtrol No. 4) and 0.2 percent H PO was added at this maximum treating temperature. After thorough agitation of the treated oil, it was cooled and filtered. The product quality was about the same as when the H PO was added at 100F. However, less foaming occurred during heating when the acid was added at the lower temperature.

EXAMPLE 16 clay and acid. The results are given in Table III below:

TABLE Ill Special Final Lovibond Colour FAC Filtrol H PQ FFA (1") (5%) Colour No. 4

2.071 1.0% 20.4% 40Y-3.5R SOY-R H 4.0% 2.071 22.8% ISY-LIR SOY-6.5K 5 6.071 2.0% 22.6% 7Y-0.7R SOY-4.5K 3

H PO -clay-heat refining of No. 2 Tallow results in very much lighter colours than those obtained in bleaching. It is possible to upgrade No. 2 Tallow by this process to a material which approaches Bleachable Tallow after caustic refining and bleaching. This is not possible with present methods. Caustic refining cannot be done since the FFA of this material is too high, and bleaching is not effective enough.

EXAMPLE 18 A sample of single-distilled oleic acid was H 1 0 clay-heat refined using various clay and acid levels. A heat test (heating the oleic acid to 200C for 30 minutes) was used to evaluate heat stability. Results of these tests are summarized in Table IV.

TABLE IV H PO.,-Clay-Heat Refined (at 360F) Special Colour F iltrol H 1 0 Lovibond Heat Test Colour No. 4 5%" Gardner Lovibond l Gardner Control l5Y-l.4R 3-4 40Y-4.2R 9-10 I9'SOYBEAN OIL FOR PAINT AND At present. caustic refined. heavil'y bleached SB oil I is supplied for this purpose. The oil must be very' light other 'by lie'ating to 340F in' the presence of acidactivated clay a'nd H PO In both'tests l .0 percent activated clay and0.5% filter aid were used. In the test at 340F, 0.1 percent H PO wasadded to the crude oil in colour after bleaching and also after heat-testing. 5 Prior to heating and the addition of the'clay- The Table V gives data on a H PO -clay-heat refi d 53 Oil ples were cooled to 200F and filtered, then bleached for comparison to a representative set of specifications and deodonzed- The results are giveh'in Table of an industrial SB oil user. 1 low: 1

r TABLE VII TABLE v CRUDE SOYBEAN OlL AClD-CLAY-HEAT TREATED Crude Clay-Heat Refined Spec C1333 Treat d at T at d t Hn Ot 1 450 F 520? A Color (Gardner) 9 l 4 l5 (no acid) (plus HI'POO Color after heat test* 4 (ppt) 2 2 Crude Free Fun r Acid(FFA) 0.37/1 0.37% Unsapomfiablt. Matter** 0.57% 0.44% Treated FFA (FFA HBPO') 071% 0.54% Color 1.1 R 1.8 R "Heat test: 50 g ufoil are heated to 500F and held at this temperature 5 minutes. L085 L507 145% H Bleached FI-A 0.71% 0.53% AOCS Method 'Ik la-64T. Color L] R 146 R Deotlorized FFA 0.02% 0.0271 Color 0.5 R 0.6 R Clay-heat refined SB Oll meets colour specifications Flavour blaind bland Schaal-oven stability 7 ays 7 'days before and after heat testing. Cold test 24 hours 23 hours EXAMPLE 20 25 Three samples of crude East Coast Herring Oil were The above two tests Show that with respect to cnlde heated in a closed container in the presence of a small soybean Oll, equivalent results can be obtained by using amount of a neutral bleachin clay (Pe bina N 75) either clay alone plus heating to about 450F or phosunder a blanket of nitrogen. After the maximum treatphoric acid and clay plus heating to only 340F. The tring temperature was reached the samples were cooled 3O a d l Can be hydrogenated. to 350F, h dro enation catal st and filter aid were added and thisari i les were hydrogenated to an end EXAMPLE 22 HaPOrCLAY'HEAT REHNING p i COMBINED WITH STEAM REFINING TO REDUCE point of 54.4 ZRI. The hydrogenated Oll was then fil- FFAS (FREE YAC D S I tered, bleached and deodorized. The results are tabulated in Table VI below: Crude palm kernel Oil (800 g), FFA 6.4 percent was TABLE VI CLAY HEAT TREATMENT AND HYDROGENATION OF CRUDE EC HERRING OIL TEST NUMBER 1 2 3 Crude FFA 0.86% 0.87% 0.87% Crude Color (Lovibond) 8.5 R 20.0 R 20.0 R Neutral Clay Treatment /27 Maximum treatment temperature 500F 500F 450F Hydrogenation temperature, 350F 350F 350F Hydrogenation time (minutes) SE] at 2l.lC 28.6 20.6 Color after hydrogenation light brownishbrownishbrown red red Active clay used to bleach hydrogenated oil /2% 1% 2% Bleached color (Lovibond) L8 R 2.8 R 1.1 R Bleached FFA 1.02% 0.91% 0.94%

Deodorized color (Lovibond) 3.0 R 0.5 R

1.0 bluc Schaal Oven stability 9 days [2 days From the above data it is shown that crude East pretreated with 0.1 percent H PO Activated clay Coast herring oil can be successfully processed by clay- 60 (2percent) and filter aid (0.5 percent) were then heat refining toahydrogenated,deodorized oil. Oil coladded. The mixture was then heated to 420F under our and flavour stability are both comparable to East vacuum. Agitation was provided by stripping the mix- Coast herring Oil refined in the conventional manner. ture with 1 percent H2O per hour, Steam tripping was 0 EXAMPLE 2] I 7 continued at 420 F for 1 hour, the charge was then 65 cooled to 230 F and filtered. The filtered 01] contained For comparative purposes two samples of crude soy bean oil were processed, one by heating to 450F in the presence of acid-activated clay without H PO and the 0.84 percent FFA; its colour was 1.6R.

It will be seen from Example 22 that the H PO -clayheat refining operation may be satisfactorily combined with steam stripping to provide a refined product of reduced free fatty acid content. This process is especially applicable to treatment of oils which have high FFA content and which are to be hydrogenated. The free fatty acids which may interfere with hydrogenation are reduced at the same time that color bodies and other impurities are being removed.

It will be seen that the process of the invention is capable of many adaptations and variations without departing from the spirit and scope thereof.

in the foregoing specification and ensuing claims all percentages, unless otherwise specified, are given in percent by weight based on the weight of the fatty substance being treated.

I claim:

1. A process for refining crude fatty substances selected from the group consisting of unrefined vegetable oils and fatty acids which comprises heating said crude fatty substances under vacuum or inert atmosphere in the presence of about 0.1 to 1.0 percent of phosphoric acid and about 0.1 to 6.0 percent of acid activated clay to a temperature of from about 325 to 500F and then filtering the resulting product.

2. The process of claim 1 wherein the crude fatty substances are selected from the group consisting of oleic acid, soybean oil, rapeseed oil, sunflower seed oil, peanut oil, palm kernel oil, coconut oil and corn oil.

3. The process of claim 1 wherein the fatty substance is pretreated with the phosphoric acid at a temperature up to about F prior to adding the bleaching adsorbent and heating to a temperature in said range.

4. The process of claim 1 wherein the fatty substance is pretreaated with about 0.1 percent phosphoric acid. the bleaching clay is added and the mixture is heated to about 325 to 350F in the substantial absence of air.

5. The process of claim 1 wherein the crude fatty substance is a vegetable oil and the hot treated oil is subjected to hydrogenation.

6. The process of claim 5 wherein the hot treated oil is directly subjected to hydrogenation prior to filtering.

7. The process of claim 1 wherein the crude fatty substance is an unrefined vegetable oil and wherein the hot treated oil is steam-stripped during the heat treatment to remove free fatty acids.

8. A process for upgrading crude oleic acid consisting essentially of heat treating said crude acid in the presence of from about 0.1 to 1.0 percent of phosphoric acid and from about 0.5 to 6 percent of acid-activated clay at a temperature in the range of about 325-375F. l l l

Claims (8)

1. A PROCESS FOR REFINING CRUDE FATTY SUBSTANCES SELECTED FROM THE GROUP CONSISTING OF UNREFINED VEGETABLE OILS AND FATTY ACIDS WHICH COMPRISES HEATING SAID CRUDE FATTY SUBSTANCES UNDER VACUUM OR INERT ATMOSPHERE IN THE PRESENCE OF ABOUT 0.1 TO 1.0 PERCENT OF PHOSPHORIC ACID AND ABOUT 0.1 TO 6.0 PERCENT OF ACID ACTIVATED CLAY TO A TEMPERATURE OF FROM ABOUT 325* TO 500*F AND THEN FILTERING THE RESULTING PRODUCT.

2. The process of claim 1 wherein the crude fatty substances are selected from the group consisting of oleic acid, soybean oil, rapeseed oil, sunflower seed oil, peanut oil, palm kernel oil, coconut oil and corn oil.

3. The process of claim 1 wherein the fatty substance is pretreated with the phosphoric acid at a temperature up to about 100*F prior to adding the bleaching adsorbent and heating to a temperature in said range.

4. The process of claim 1 wherein the fatty substance is pretreaated with about 0.1 percent phosphoric acid, the bleaching clay is added and the mixture is heated to about 325* to 350*F in the substantial absence of air.

5. The process of claim 1 wherein the crude fatty substance is a vegetable oil and the hot treated oil is subjected to hydrogenation.

6. The process of claim 5 wherein the hot treated oil is directly subjected to hydrogenation prior to filtering.

7. The process of claim 1 wherein the crude fatty substance is an unrefined vegetable oil and wherein the hot treated oil is steam-stripped during the heat treatment to remove free fatty acids.

8. A process for upgrading crude oleic acid consisting essentially of heat treating said crude acid in the presence of from about 0.1 to 1.0 percent of phosphoric acid and from about 0.5 to 6 percent of acid-activated clay at a temperature in the range Of about 325*-375*F.