CA1156675A - Fractionation of triglyceride mixtures - Google Patents

Abstract

FRACTIONATION OF TRIGLYCERIPE MIXTURES

ABSTRACT

Triglyceride mixture is fractionated (on the basis of Iodine Value) utilizing selected surface aluminated silica gel adsorbent and selected solvent(s).

Description

1 1~6675 FRACTIONATION OF TRIGI,YCERIDE MIXTURES
Ted J. ~ogan and Richard M. King Technical Field . . .
The field of the invention is the separation of triglyceride mixture to obtain product(s) of Iodine 5 Value different from that of said mixture.
The inven~ion is useful, for example, to remove a particular ~ndesirable lower Iodine Value fraction. A
very important application of this is the treatment of oils with mostly unsaturated fatty acid moieties (e.g.
10 sunflower oil) to reduce the content of triglyceride with fatty acld moiety having saturated carbon chain.
This allows production of a salad or cooking oil with essentially 2ero percent saturates (by F~A nutritional standards).
The invention is also useful, for example, to remove an undesirable higher Iodine Value fraction from a feed-stock. An important application of this is the processing of soybean oil to reduce the content of triglyceride with linolenic acid moiety to minimize the development of 20 rancidity and odor and thexeby obtain the benefits of touch hardening without the disadvantages of cis to trans ., . ~
isomerization, double b~nd position changes and need to remove catalyst and hydrogenation odor.
Other important applications of the invention are the ~ -25 recovery of increased trilinolein level composition from regular safflower oil and the recovery of increased triolein level composition from high oleic safflower oil.
The invention is also useful for obtaining particular Iodine Value cuts for any speçial purpose.
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Background Art Logan et al, U.S. Patent 4,297,292, issued October 27, 1981, discloses the fractionation of triglyceride mixtures utilizing macroreticular strong acid cation exchange resin adsorbents. The invention herein differs, for example, in utilizing an adsorbent which is advantageous over that used in U.S. Patent 4,297,292 from the standpoints of flexibility, dynamic capacity, cost, and of being inorganic rather than organic in nature.
It is known to remove various non-triglyceride impur-ities from triglyceride mixtures utilizing various aluminosilicate adsorbents. See, for example: U.S. Patent ~o. 852,441; U.S. Patent No. 2,288,441; U.S~ Patent No.

2,314,621; U.S. Patent 2~509,509; U.S. Patent No.
2,577,079. This kind of art discloses using alumino- ~;
silicates to decolorize, deodorize, treat used oil, refine, remove trace metals, remove catalyst and remove free fatty acid. The process herein differs, for example, in the ~eedstock which is essentially free of the type of impurities to which this body of prior art is addressed to removing.
It is known on an analytical scale to separate tri-glyceride mixtures utilizing silica gel treated with silver nitrate. See, for example, Journal of the American Oil Chemists Society, 41, pp. 403-406 (June 1964). The adsorbent there has the disadvantage of having a short life cycle in that the silver nitrate being not chemically attached is leached out. The adsorbent used herein has no such short life cycle problem.

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U.S. Patent No. 2,197,861 suggests the possibility of utilizing an aluminosilicate to cause polymerization in an animal, vegetable or marine oil whereby unpolymerized material is readily separated from polymerized material.
Such a process would have the disadvantage of producing unuseful polymerized material. The process of the instant invention is carried out without significant polymeriza-tion occurring.
Neuzil et al U.S. 4,048,205 and Neuzil et al U.S.
4,049,688 and Logan et al U.S. Patent 4,210,594 issued July 1, 1980, disclose the fractionation of alkyl fatty carboxylate mixtures using synthetic crystalline alumino-silicates (zeolites). These crystalline aluminosilicate adsorbents typically contain up to about 25% amorphous aluminosilicate, e.g., clay. The process of the invention herein differs, for example, in the feedstock. The process of the invention herein also differs in the adsorbent which is advantageous over the crystalline zeolite adsorbents from the standpoints of versatility (in that, with the adsorbent herein, the same equipment and packing is advan-tageously used for separation of alkyl carboxylates and triglycerides - this is not true for crystalline zeolites), flexibility (in that various ratios of surface~silicon atoms to aluminum atoms and various surface areas are readily available for the adsorbent herein - there is substantially less choice for crystalline ~eolites), and dynamic capacity (in respect to selectively adsorbing triglyceride of higher Iodine Value).

,~t l 1 SB67 5 Lam et al, "Silver Loaded Aluminosilicata As a Stationary Phase for the ~i~uid Chromatographic Separation of Unsaturated Compounds", ~ Chromatog. Sci. 15(7), 234-8 (1977) discloses the analytical (chromatographic) separation 5 of bromophenacyl carboxylates on the basis of unsaturation utilizing silvere~, surface aluminated silica gPl absorbents of microparticulate par~icle size (which particle size is not readily handled in a non-analytical commercial context and can res~lt in significant loss due to suspension of 10 particles in solvent). The process of the instant invention differs at least in the feedstock and the adsorbent particle size.

Broad ~escription ~f the Invention It is an object of this invention to provide a process 15 for fractionating triglyceride mixtures on the basis of Iodine Value utilizing an adsorbent which is made from low cost and readily available materials, which is readily provided with selected characteristics (ready choice in ratio of s~rface-silicon atoms to aluminum atoms, silica 20 gel pore size and s~rface area, and cation s~bstituents and level thereQf), which is not s~bject to a cation leaching problem (as is silver nitrate treated silica gel), which has a particle size appropriate for commercial processing ;~
(no significant handling or ~oss problems as ~ith micro- ~-25 partic~late particle sizes), which is advantayeous over crystalline zeolite adsorbents from the standpoints of flexibility and dynamic ~apacit~ and which is advantageous over resin adsorbents from the standpoints o~ flexibility, dynamic capacity, cost, an~ Q~ ~eing inorganic in nature.

7 ~

This object and other objects and advantages are readily obtained by the invetnion herein as described below.
The invention herein involves fractionating tri-glyceride mixture, on the basis of Iodine Value, utilizingselected solvent(s) and selected surface aluminated silica gel adsorbent.
The feed (sometimes called feedstock) is a mixture of triglycerides with different Iodine Values (a mixture 10 of triglyceride of higher Iodine Value with triglyceride of lower Iodi~e Value) which is to be separated to produce fractions of higher Iodine Value and lower Iodine Value~ ;
The triglycerides in the feed have carboxylic acid moieties which contain carbon chains containing from ~ to 26 carbon 15 atoms. It is important that the feed is essentially free of impurities which can foul the adsorbent thereby causing loss of fractionating performance.
The feed is dissolved in particular solvent ( the adsorption vehicle)~ The solution which is formed is 20 contacted with particular surface aluminated silica gel adsorbent. Triglyceride of higher Iodine Value is selectively adsorbed on such adsorbent, and a fraction of the mixture which is enriched (compared to the feed) in content of triglyceride of lower Iodine Value is left 25 in solution.

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Solution of the fraction which is enriched in content of triglyceride of lower Iodine ~alue is remo~ed from contact with the adsor~ent which has selectiuely adsorbed triglyceride of higher Iodine ~alue; this solution is 5 denoted a raffinate. Fraction enriche~ in content of triglyceTide of lower Iodine ~al~e can readil~ be reco~ered from the raffinate as described later.
The adsor~ent which has selectively adsorbed thereon triglyceride of higher Iodine ~alue is contacted with lO particular soluent (the desorbent) to ca~se desorption of adsorbed triglyceride and provide a solution in the soluent of fractiQn enriched (compared to the feed) in content of triglyceride of higher Iodine ~alue.
SolutiQn in soluent of fractiQn enriched in content of 15 triglyceride of higher Iodine ~alue is remoued from contact with the adsorbent which has ~ndergone desorption of triglyceride; this sol~tio~ is denoted an e~tract. Fraction enriched in content of triglyceride of higher Iodine Value can be readily recouered from the extract as described later.
Preferred is a process where the svlvent which is ~sed tQ dissolue feed for selective adsorption (that is, the adsorption uehicle), and the soluent which is used as the vehicle for desorpti~n (that is, the desorben~) have the same composition. Such proce~s is conveniently referred to 25 herein as a one soluent process. PreEera~ly, such one solyent process is carrie~ o~t continuously u~ilizing a simulated movin~ bed uni~ operation.
, l ~ SB~7 5 Less preferred is a process where the solvent which is used as the dissolving phase during adsorption and the solvent which is used as the vehicle for desorption have different compositions. This process is conveniently referred 5 to herein as a two solvent process.
In general, the solvent(s~ utilized herein (whether in a one solvent process or in a two solvent process~ is (are) characterized by a solubility parameter (on a 25C.
basis) ranging from about 7.0 to about 15.0, a solubility 10 parameter dispersion component (on a 25C. basis) ranging from about 7.0 to about 9.0, a solubility parameter polar component (on a 25C. basis) ranging from 0 to about 6.0 and a solubility parameter hydrogen bonding component (on a 25C. basis) ranging from 0 to about 11.5.
The surface aluminated silica gel adsorbent for the process herein is a synthetic amorphous alumina-silicate cation exchange material. It is homogeneous with respect to silicon atoms but not with respect to aluminum atoms;
aluminum atoms are present essentially entirely at the 20 surface of the adsQrbent (i.e., they are associated with surface-silicon atoms) and are considered to be essentially completely in the form of aluminate moieties.
The adsorbent is derived from silica gel having a mean pore diameter of at least about 50 angstroms and a 25 surface area of at least about 100 square meters per gram.

The adsorbent is further charactcrized by a ratio of surface-silicon atoms to aluminum atoms ranging from about

3:1 to about 20:1, a moisture content less than about 10~
by weight, and a particle size ranging frQm about 200 mesh to about 20 mesh.
The adsorbent has cation substituents selected from the group consisting of cation substituents capable of forming .~r complexes and cation substituents not capable of forming ~ complexes and combinations of these.
The adsorbent is formed by first treating particular silica gel wi~h aluminate ion; then, if necessary, adjusting the cation content (e.g. by providing a selected level of cation substituents capable of forming ~ complexes); and adjusting the moisture content. Particle size can also be lS adjusted.
The solvcnt(s) (that is, the adsorption vehicle and the desorbent, whether in a one solvent process or a two solvent process), the ratio of surface-silicon atoms to aluminum atoms in the adsorbent, and the level of cation substituents capable of forming ~ complexes (which level can range from none at ~11 up to 100~ of exchange capacity) are selected to provide selectivity during adsorption and satisfactory desorption of adsorbed triglyceride.
Processing is carried out without significant poly-merization of triglyceride occurring.
The invention herein contemplates one stage processingas well as processing in a plurality of stages. One stage processing is suitable for separating a mixture into two fractions. Multistage processing is suitable for scparating a mixture into more than two fractions.

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g As used herein, the term "selectively" in the phrase "selectively adsorb" describes the ability of the adsorbent to preferentially adsorb a component or components. In practice, the component(s) which is (are) preferentially adsorbed, is (are) rarely evcr the only component(s) adsorbed. For example, if the feed contains one part of a first component and one part of a second component, and O.S
parts of thc first component and 0.2 parts of -the sccond component are adsorbed, the first compQnent is selectively adsorbed.
The magnitude of the selective adsorption is expressed herein in terms of relative selectivity, that is, the ratio of two components in the adsorbed phase (extract) divided by the ratio of the same two components in the unadsorbed phase (raffinate). In other words, relative selectivity as used herein is defined by the following equation:

Selecti~ity= [Concentration M/Concentration N~A
[Concentration M/Concentration N]U

where M and N are two components of the feed represented in volume ~r weight percent and the subscripts A and U
represent the adsorbed and unadsorbed phases respectively.
When the selectivity is l.~, there is no preferential adsorption of one component over the other. A selectivity larger than 1.0 indicates preferential adsorption of component M; in other words, the extract phase is enriched 1~ 5~B7 5 in M and the raffinate phase is enriched in N. The ~arther removed the selectivity is from 1.0, the more complete the separation.
The amount selecti~ely adsorbed per unit uolume of adsorbent in a batch equilibrium test (mixing of feed dissolved in solvent with adsorbent for up to one hour or until no further change in the chemical comp~si~ion of the liquid phase occurs) is the static capacity of the adsorbent.
An advantage in static capacity indicates a potential advan-tage in dynamic capacity. Pynamic capacity is the productionrate in continuo~s operatiqn in appara~us of predetermined size to obtain predetermined purity product(s).
The meaning of the terms "triglyceride of higher Iodine Value" and "triglyceride o lower Iodine Value" as used herein depends on the context of the application of the invention. The "~riglyceride Q ~ligher Iodine ~alue" has to include the triglyceride of highest Iodine Value and can and often does c~nsist of a plurality of triglycerides of different Iodine Yalues. The "triglyceride of lower Iodine Value" has to include the triglyceride of lowest Iodine Value (e.g. saturated triglyceride, i.e., triglyceride having all fatt~ aci~ moie~ies ha~ing saturated carbon chains, if such is present in the mixture ~eing separated) and can and often does consist o~ a plurality of triglycerides o different Iodine Values. The important point is that the separation is one on the basis of Iodine Value.

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The term "Iodine ~alue" is used in its normal meaning in relation to degree of unsaturation of fats and is described fully in Swern, Bailey's Industrial ~il and Fat -Products, Interscience, 3rd edition, pages 63 and 64.
The composition of triglyceride mixtures is sometimes referred to herein as containing a percentage of particular fatty acid moiety "on a methyl ester basis" or "on a fatty methyl ester basis" or is defined "on a methyl ester basis"
as containing percentages o methyl esters. Such percentages are obtained by determining the weight percentage of particular methyl ester in the methyl ester mixture obtained by converting triglyceride fatty acid moieties into corresponding methyl esters. Thus, for example, a trigly-ceride mixture containing 7~ linolenic acid moiety Qn a '!i j methyl ester basis means that the methyl ester mixture obtained on con~erting the fatty acid moieties of such tri-glyceride mixture contains by weight 7~ meth~l linolenate.
The term "sol~ent" as used herein refers both to solvent blends (i.e , sol~ents consisting of a plurality of constituents) and to pure compounds, (i.e., solvents consisting of a single constituent) ~nless the context indicates otherwise.
The terms "solubility parameter", "solubility parameter dispersion component", "solubility parameter polar component"
and "solubility parameter hydrogen bonding component" as used herein are defined by equations 6-10 at page 891 of Kirk-Othmer, ~ncyclopedia o Chemical Technolo~y, 2nd edition, Supplement Volume, published by Interscience Publishers (John Wiley ~ Sons), New York, 1~71. ~alues herein for ,., - 115~75 ~12-solubility parameter, solubility parameter dispersion component, solubility parameter polar component and solubility parameter hydrogen bonding component are for solvents at 25C. (i.e., they are on a 25C. basis). As on page 891, the symbols "~ D"~ "~p", and "~H" are used herein to re~er respectively to "solubility parameter", "solubility parame~er dispersion component", "solubility parameter polar component'~, and "solubility parameter hydrogen bonding component". For many solvents the values for ~D~ ~p and ~H
are given in Table I which directly follows page 891 and the value for ~ is calculated using equation ~6) on page 891.
For solvents consisting of a plurality of constituents, the values for "~D" "'~p", and "~H" are calculated by summing the corresponding values for the constituents mul~iplied by their volume frac~ions and the value for "~" is calculated using equation (6) on page 891.
The "surface area" of the silica gel is measured by the B.E.T. nitrogen adsorption technique described in Brunauer, Emmett and Teller, J. Am. Chem. Soc. 60, p. 309 (1938).
The "mean pore diameter" of the silica gel is determined by determining pore volume, determining surface area as described above, assuming that the pores are cylindrical and that the entire surface area consists of the surface of cylindrical pores, and solving simultaneous equations. Porc volume is readily determined by techniqucs well known in the art (see, for example, Introduction to Powder Sur~ace Area, S. Lowell, John Wiley ~ Sons, N.Y. 1979).

1 1~6675 The term "surface-silicon atom" as used herein means a silicon atom attached to only three other silicon atoms by Si-O bonds.
Determination of the ratio of sur~ace-silicon atoms to aluminum atoms in the surface aluminated silica gel adsorbent is readily carried out by determinin~ the number of surface-silicon atoms assumin~ the presence of 8 silicon atoms per square nanometer of surface area (the fi~ure of 8 silicon atoms per square nanometer of surface area is found, for example, in Iler, R.K.
The Colloid Chemistry of Silica and Silicates, Cornell University Press, Ithaca, New York 1955, p. 58) of the silica gel from which the adsorbent is derived and determining the number of aluminllm atoms, for example, utilizing elemental analysis, and calculating.
The term "cation substituents" means the exchange-able cations associated with the adsorbent. The "ca-tion substituents capable of forming ~ complexes" are cation substituents capable of attracting and holding unsaturated materials (the greater the degree of unsaturation, the greater the attracting and holding power) by formation of a particular kind of chemlsorption bondin~3 known as 7r bonding. The "cation substituents not capable of forming rr complexes" do not have significant ability to form such che~isorption b~nds. Ihe formation of ~r complexes is considered to involve two kinds of bonding: (1) overlap between occupied ~ molecular orbital of an unsaturate and an unoccupied d orbital or dsp~hybrid orbital of a metal and (2) overlap between an unoccupied antibonding ~ molecular orbital of the unsaturate and one of the occupied metal d or dsp~hybrid orbitals (sometimes referred to as "back bonding"). This rr complexing is described, for example, in ~hem. Revs. 68, .. . .. .. . . . .. . .. . . . . . . . ... .. . . ...... ...

1 ~v~7~

pp. 785-806 (1968).
The term "adsorben-t surface area" as used hereinafter in defining s~lver substituents level ;s also measured by the B.E.T. nitrogen adsorption technique referred to above and is measured on the adsorbent after silvering and moisture adjustment.
The level of silver substituents is referred to hereinafter i~n terms of millimoles/lO0 square meters of adsorbent surface area. This is determined by determining the amount of silver (e.g. by elemental microanalysis or utilizingX-ray fluorescence), by obtaining the adsorbent surface area as described above and calculating.
The term "moisture content" as used herein in relation to the adsorbent means the water present in the particles of adsoxbent according to measuremen-t by Karl Fischer titration or by determining weight loss on ignition at 400C. for 2-4 hours. The moisture content values presented herein are percentages by weight.

Detailed Description The triglycerides in the feed have the formula o CH -O-CR

H - O-CR
1 IOj in which each R is aliphatic chain which contains 5 to 25 carbon atoms and is the same or different within a 1~56675 molecule, The aliphatic chains can be satura-ted or unsaturated. The unsaturated aliphatic chains are usually mono-, di- or triunsaturated, The triglyceride mixtures for feed into a one stage process or into the first stage of a multistage process can be or are readily derived from naturally occurring fats and oils such as, for example, butter, corn oil, cottonseed oil~ lard, l;~nseed oil, olive oil, palm oil~ palm kernel oil~ peanut oil~ rapeseed oil, safflower oil Cboth regular and high ole~c~
sardine oil, sesame oil~ soybean oil, sunflower oil and tallow, It ~s important that the triglyceride feedstock is essentially free of impur;~ties such as gums~ free fatty acids, mono- and diglycerides, color bodies, odor bodies, etc. which can foul ~i~e. deactivate) the adsorbent thereby causing loss of fractionating pexformance~
Such impurities are non-triglycerides which would be preferentially adsorbed and not desorbed thereby in-activating adsorption sites~ The clean-up of the feed-stock is accomplished by numerous techniques known in the art, such ~s alkali refIning, bleaching with Fuller's Earth or other active adsorbents~ vacuum-steam stripping to remove odor bodies, etc~
One very important feedstock i:s refined and bleached sunflower oil~
Another important feedstock is refi~ed~ bleached and deodorized soybean oil containing from about 6,5%
to about 8.5% by we~ght of linolenic acid moiety on a fatty methyl ester basis and having an Iodine Value ranging from about 130 to about 150.
Still another important feedstock is refined, bleached and deodorized safflower oil (essentially free of wax and free fatty acids).
In a one solvent process, the feed is usually ~ . . . . .. . . .. . . . . . ... ... .. . . . . .. . . ..... . ..

7 ~

introduced into the adsorbing unit without solvent and is dissolved in solvent already in the unit, in-troduced, for example, in a previous cycle to cause desorption.
If desired, however, the feed in a one solvent process can be dissolved in solvent prior to introduction into the adsorbing unit or the feed can be raffinate or extract from a previous stage comprising triglyceride mixture dissolved in solvent. In a two solvent process, the feed is preferably dissolved in the solvent constituting the vehicle for adsorption prior to intro-duction into the adsorbing unit.
Turning now to the solvents useful herein for a one solvent process (where the same solvent composition performs the dual role of being the dissolving phase during adsorption and the vehicle for desorption), these are preferably characterized by ~ ranging from about 7.0 to about 10.5, ~D ranging from about 7.0 to about 9.0, ~p ranging from about 0.~ to about 5.1 and ~H ranging from about 0.3 to about 7.4. ~lore preferred solvents for use in a one solvent process herein are characterized by ~ ranging from about 7~ to about 9 ~ ~D ranging from about 7.25 to about 8.0, cp ranging Erom about 0.5 to about 3.0 and ~H ranging from about 0.7 to about ~Ø
One important group of solvents for a one solvent process includes those consisting essentially by volume of from 0% to about 90% C5-C10 saturated hydrocarbon (that is, saturated hydrocarbon with from 5 to 10 carbon atoms) and from 100% to about 10% carbonyl group containing compound selected from the group consisting of (~) ester having the formula ,, , , , . . . . , , . , , , .. . , , . ~ " . ..

1 ~56~7~
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, Rl-C-O-CH2-R2 wherein Rl is hydrogen or alkyl chain containin~ one or two carbon atoms and R2 is hydrogen or alkyl chain containing one to three carbon atoms and (b) ketone having the formula R3-C-R3 wherein each R3 is the same or different and is alkyl chain containing 1 to 5 carbon atoms. Examples of suitable hydrocarbons are pentane, hexane, heptane, octane, nonane, decane, isopentane and cyclohexane.
Examples of esters suitable for use in or as the solvent are methyl formate, methyl acetate, ethyl acetate, methyl propionate, propyl forma-te and butyl formate. Examples of ketones suitable for use in or as the solvent are acetone, methyl ethyl ketone, methyl isobutyl ketone and diethyl ketone.
Another important group of solvents ~or a one solvent process are dialkyl ethers containing 1 to 3 carbon atoms in each alkyl group and blends of these with the hydro-carbon, ester and ketone solvents set forth above.Specific examples of solvents within this group ar~
diethyl ether and diisopropyl etner.
Yet another important group of solvents for a one solvent process are blends of Cl 3 alcohols (e.g. from - 25 about 5% to about 40~ by volume alcohol) with the hydrocarbon, ester and ~etone solvents set forth above.
Specific e~amples of solvents within this group are blends of methanol or ethanol with hexane.
Very preferably, the solvent for a one solvent process comprises ethyl acetate with blending with hexane 1 1~667~

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- being utilized to weaken the solvent and blending with ethanol being utilized to strengthen the solvent.
In most continuous one solvent processes envisioned within the scope of the invention, the solvent is introduced into the process in a desorbing zone and sufficient solvent remains in the process to perform at a downs-~ream location the dissolving function for adsorption.
The solvent to feed ratio for a one solvent process generally ranges on a volume basis from about 4:1 to about lO0:1 and preferably ranges from about 5:1 to about 40:1.
We turn now to the solvents useful herein for a two solvent process (where different solvent compositions are used as the dissolving phase during adsorption and as the vehicle for desorption).
For a two solvent process herein, the solvents for use as the dissolving phase during adsorption, i e., as the adsorption vehicle, are pre~erably characterized by ~ ranging from about 7.3 to abou-t 14.9, ~D ranginy from about 7.3 to about 9.0, ~p ranging from 0 to abou-t 5.7 and ~H ranging from 0 to about llØ More preferred solvents for the adsorL~tion vehicle for a two solvent process herein are characterized by ~ ranging from about 7.3 to about 9 0~ ~D ranging from about 7.3 to about 8.0, ~p ranging from 0 to about 2.7 and ~ ranging from 0 to about 3.6. Very preferabIy, the solvent for ~he adsorption vehicle in a two solvent process herein is hexane or a blend consisting essentially of hexane and up to about 15% by volume ethyl acetate or diisopropyl etller.

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For a two solvent process herein, the solven-ts Eor use as the vehicle for desorption, i..~., as the desorbent, are preferably characterized by ~ ranging from about 7.4 to about 15.0 and at least 0.1 yreater than the ~ of the adsorption vehicle, ~D ranging from about 7.3 to about 9.0, ~p ranging from about 0.3 to about 6.0 and at least 0.3 greater than the ~p of the adsorption vehicle, and ~H ranging from about 0.5 to about 11.5 and at least 0.5 greater than the ~ of the adsorption vehicle. More preferred solvents for the desorbent for a two solvent process herein are characterized by a ~ ranging from about 7.4 to about 10.0, ~D ranging from about 7.3 to about 8.0, ~p ranging from about 0.5 to about 4.0, and ~H ranging from about O.S to about 6.0 and having ~, ~p and ~H' respectively, greater than the ~, ~p and ~H of the adsorption vehicle by at least the amounts stated above.
Important desorbents for use in a two solvent process herein include: ethyl acetate; blends consisting essentially of ethyl acetate and up to about 80% by volume hexane; blends consisting essentially of ethyl acetate and up to about 25% by volume methanol or e-thanol;
and diisopropyl ether. Very preferably, the solvent for the desorbent in a two solvent process herein comprises ethyl acetate.
It is preferred bo-th in a one solvent process herein and in a two solvent process herein to avoid use of halogenated hydrocarbon solvents as these shorten adsorbent life.
We turn now in de-tail to the adsorbent for use .. . ..

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herein. It is defined the same regardless oE whether it is used in a one solvent process or in a two solvent process.
The bonding of aluminate groups to surface-silicon atoms of the silica gel from which adsorbent herein is derived to provide the adsorben-t herein characterized by aluminum atoms present essentially ent.ire].y in anionic moieties at the surface is indicated by the following chemical structure which is believed to .represent anionic sites in such adsor-bent:

~ -7-- Si O Al - OH
! o --si--_ I _ ., wherein the silicon atoms which are depicted are surface-silicon atoms. The cation substituents are associated with such anionic sites to provide electrostatic neutrality.
The characterization of the adsorbent in terms of mean pore diameter and surface area of the silica gel from which it is derived is important to obtaining appropriate dynamic capacity.
If adsorbent is used derived ~rom silica gel starting material with a mean pore diameter of less than .. . ..

the aforestated lower limit of about 50 angstroms, dynamic capacity becomes quite low. This me~ns that the separation is not as complete or that a large number of columns have to be used ln the simula-ted moving bed unit operation described hereinafter or very low flow rates or long contact times are required to be used to obtain good separation. This is because with small diameter pores, the triglyceride cannot yet into the interior in the time allotted and the accessible portions of the adsorbent become saturated and the partition coefficient approaches zero and mass transfer ceases. The silica gel surface area normally corxesponding to a mean pore diameter of about 50 angstroms is about 600 square meters per ~ram.
If adsorbent is used d~rived from silica gel starting materidl having a surface area less than tile alores~atec~ lo~eL limit of about 100 square me-ters l:>er gram, both static and dynamic capacity become quite low. This means separation is poor even with low production rates, long processing times or a large number oE col~mns. The silica gel mean pore diameter normally corresponding to a surface area of about 100 square meters per gram is about 200 angstroms.
Preferably, the adsorbent herein is derived from silica gel having a mean pore diameter of at least ahout 75 angstroms and a surface area of at least about 300 square meters per gram. The silica gel surface area normally corresponding to a mean pore diameter of about 75 angstroms is about 475 square meters per gram. The silica gel mean pore diameter normally corresponding to a surface area of about 300 square meters per gram is about 120 angstroms.
The characterization of the adsorbent herein in ~erms of ratio of surface-silicon atoms to aluminum atoms is 5 important in relation to selectivity. The lower limit of about 3:1 is related to the chemical structure of the adsorbents herein; in such structure, alumina~e moiety is associated with three silicon atoms. The upper limlt of about 20:1 has been selected to provide sufficient adsorblng power 10 to obtain selectivity in some fractionation envisioned. In most instances in important applications of this invention, the adsorbent preferably is characterized by a ratio of surface-silicon atoms to aluminum atoms ranging from about 3:1 to about 12:1.
We turn now to the cation substituents of the adsorbent.
The catiQn $ubstituents capable of forming ~ complexes are preferably selected from the group consisting of silver (in a valence state of 1), copper (in a valence state of 1), platinum (in a valence state of 2), palladium (in a valence 2Q state of 2) and combinations of these.
The cation substituents not capable of forming complexes are preferably selected from the group consisting of cation substituents from Groups IA and IIA of the Periodic Table and zinc cation substituents and combinations of these 25 and very preferably are selected from the group consisting of sodium, potassium, barium, calcium, magnesium and zinc substituents and combinations of these.

1 ~56~75 Most preferably, the adsorbent has cation substituents selected from the group consisting of silver substituents in a valence state of one and sodium substituents and combina-tions of these.
Preferably, cation substituents such as hydrogen, which cause ~eteriOratiQn of the adsorbent structure ~e.g.
by stripping aluminum therefrom) should be avoided or kept at a minimum.
Fractionations are enuisioned herein utilizing adsorbent with no cation substituents capable of forming complexes (e.g. together Wit]l a weak solvent as the adsorp-tion vehicle). Such adsqrbent functipns by a physical adsorption mechanism to preferentially adsorb triglyceride of higher Iodine Value. Preferabl~ however, the adsorbent utilized has cation substituents capable of forming ~
complexes as at least some of its cation s~stituents; these adsor~ents function ~y a C~m~inatiQn of physical adsorption and the type of chemical adsorption known as ~ complexing to preferentially adsorb triglyceride of hi~her Iodine Value.
~ery preferably, the adsorbent has a level of silver substituents greater than a~out ~.05 millimoles/100 sq~are meters of adsorbent surface area. The upper limit on silver is found in a fully silver exchanged adsorbent with a ratio of surface-silicon atoms to aluminum atoms of about 3:1 and is about Q.44 m.illimoles/100 square meters of adsorbent surface area. Most preferably, the adsor~ent has a silver level ranging from about 0.10 millimoles/1~0 square meters `

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1 ~5~67~

of adsorbent surface area to about O.~S millimoles~100 square meters of adsor~ent surface area. Amount of silver is readily measured utilizing x-ray fluorescence or elemental microanalysis.
The ratio Qf surface-silicon atoms to aluminum atoms and the level of ca~ion su~stituents capable of forming ~ complexes interrelate, and the selection of these governs - ;
adsorbing power and therefore selectivity. These also have an effect on static and on d~namic capacity.
The ratio ~f surface-silicon atoms to aluminum atoms selected sets the maximum amount of catiQn su~stituents capable of forming ~ comple~es that can be introduced. This is because the cation subs~ituents are held by the negative charges associated with aluminum atoms in anionic moieties, with a monoualent cation substituent ~eing held by the charge associate~ with a single aluminum atom an~ a divalent cation substituent being held ~y the charges associated with two aluminum atoms.
With the silica gel star~ing material surface area held constant, and with the lewel of cati~n substituents capable of f~rming ~ complexes being held at the same percentage of exchange capacity, as the ratio o surface-silicon atoms to aluminum at~ms is increased, the adsorbing power and capacity (static and ~ynamic) decreases. With the surface area of the silica gel starting material held constant and with the ratio of surface-silicon atoms to aluminum atoms held constant, increasing the level of cation .

, .
. . , ~ , .. . ..

1 ~B675 substituents capable of forming ~ complexes results in increasing adsorbing power and capacity ~static and dynamic).
With the ratio of surface-silicon atoms to aluminum atoms held constant and the level of cation substituents capable of forming ~ complexes held constant, using adsorbent derived from silica gel of increased surface area increases capacity ~static and dynamic) up to the point where increase in silica gel starting material surface area results in decrease in mean pore diameter to the extent that dynamic capacity is adversely affected.
The moisture content is important in the adsorbent because too much moisture causes the adsorbent to be oleo-phobic (water occupies pores of the adsorbent preventing feed from reaching solid surface of the adsorbent). The less the moisture content is, the greater the adsorbing power and capacity. The upper limit of about lO~o by weight moisture content has been selected so that the adsorbent will perform with at least mediocre efficiency. Preferably, the moisture content in the adsorbent is less than about 4~ by weight.
The adsorbents herein generally have particle sizes ranging from about 200 mesh to about 20 mesh (U.S. Sieve Series). Use of a particle size less than about 200 mesh provides handling problems and can result in loss of adsorbent as a result of very small particles forming a stable suspension in solvent. Use of a particle size greater than about 20 mesh results in poor mass transfer.
For a continuous process, particle sizes of about 80 mesh to about 30 mesh (U.S. Sieve .

:- `" 1 3.5~75 i , .

Series) are preferred; using particle sizes lar~er than about 30 mesh reduces resolution and causes diffusion (mass transfer) limitations and using particle sizes less than about 80 mesh results in high pressure drops. Preferably, there is narrow particle size distribution within the aforestated ranges to provide good flow properties, We turn now to the preparation of the adsorbent.
The silica gel starting material is selected on the basis of mean pore diameter, surface area and particle size. As indicated above, the mean pore diameter must be at least about 50 angstroms, and the surface area must be at least about 100 square meters per gram. The particle size must be at least about 200 mesh since the adsorbent has a particle size approximately the same as the particle size of the silica gel particles which are reacted to provide the adsorbent. Thus, microparticulate silica gels are unacceptable for use in producing the adsorbent hereinO
Silica gel starting materials including particles with a size greater than 20 mesh are readily made useful, for example/ by sieving out larger particles if only some are present or by size-reducing and sieving if a substantial part of the particles is too large. Preferred silica gel starting materials are sold under the tradenames Silica Gel 100 ~ and Geduran ~ tboth are manufactured by E. Merck and Company) and Grade 59 Silica Gel ~ (manu-factured by the Davison Chemical Division of W.R. Grace).
Silica Gel 100 and Geduran are obtainable in particle size of 35-70 mesh. Grade 59 Silica Gel is obtainable in a 1~5~75 particle size of 3-8 mesh and must undergo size reduction and sieving.
The aluminate ion can be furnished by using a water soluble aluminate or a source thercof (in other words, the aluminate can be formed in situ). Preferred water-soluble aluminate reactants ar~ sodium aluminate and potassium aluminate. Aluminate is suitably formed in situ, for example, by reacting cationic aluminum (e.g., from aluminum nitrate) with sodium hydroxide, or by reacting aluminum metal with sodium hydroxide.
The reaction involving aluminate ion and silica gel is suitably carried out as follows: Firstly, an aqueous solution of aluminate ion ~or precursors thereof) is contacted with selected silica gel. The amount of aluminate ion is selected to provide the desired ratio of surface-silicon atoms to aluminum atoms. Reaction temperatures range, for example, from about 15C. to about 100C. and reaction times range, for example, from about 1 to about 48 hours.
In one useful process, reaction is carried out at room temperature. In another useful process, boiling water ~100C ) is used as the reaction medium. Reaction is carried out to obtain the desired surface alumination. After the surface alumination is completed, it is desirable to wash the product, e.g. with distilled water, to remove excess 25 aluminum salts. ;
Lam et al, cited above, suggest the following reaction equation:

, 1 15667 ~

-1 -Si-- -1 - ~
r I ~lo~ ~ OH l I ~
3 tsi o~ ~Al ~ ~ O _ Al_ OH¦ ~ 3H~O

- si.
. ~.
If the surface alumination reaction described above does not provide the proper cation substituents in the selected level, a cation exchange is carried out.
The cation exchange to provide a selected level of cation substituents capable of forming ~ complexes is readily carried out by contacting the aluminated material with a sufficient amount of cation that is desired to be introduced.
When it is desired to introduce silver substituents to provide cation substituents capable of forming ~ complexes, the exchange is carried out in aqueous medium. Suitable sources of silver include silver nitrate which is preferred and silver fluoride, silver chlorate and silver perchlorate.
When the level of cation desired to be introduced is sub-stantially less than 100~ of exchange capacity, reaction is 15 preferably carried out in a stirred tank and a slight excess ;
of cation (preferably 105-115~ of stoichiometric) is desirably used. When the level of cation desired to be introduced approaches 1003 of exchange capacity, reac~ion is preferably carried out in a packed column and a large excess (preferably 200~ of stoichiometric) is used. Unreacted cation is readily washed from the product.
The moisture content is readily adjusted with ;
conventional drying methods. For example, drying is readily carried out using vacuum or an oven (e.g. a forced draft oven~. Drying is carried out to obtain the desired moisture level, e.g., by drying at a temperature of 100C.-110C. for 15-20 hours.

, ~ ~56~75 The particle size of the adsorbent is preferably adjusted by adjusting the particle size of the silica gel starting material, for example by sieving ~screening) to obtain a narrow size distribution of particles within the aforedescribed range and by si~e reducing when such is appropriate. Particle size of adsorbent is readily controlled in this manner because particle size of the aluminated reac-tion product is essentially the same as that of the silica gel reactant. Less preferably, sieving or size-reduction can be carried out on aluminated reaction product or even on reaction product subsequent to cation treatment.
Turning now to the instant fractionation process, the selection of solvent(s), the ratio of surface-silicon atoms to aluminum atoms in the adsorbent and level of cation substituents capable of forming ~ complexes are interrelated and depend on the separation desired to be obtained. The lower the ratio of surface-silicon atoms to aluminum atoms in the adsorbent is, the greater the adsorbing power is. The ;
higher the level of cation substituents capable of forming ~ complexes is, the greater the adsorbing power and the greater the rèsistance to desorption. The lower the solu- ;
bility parameter and solubility parameter polar and hydrogen bonding components of the solvent utilized as the dissolving phase during adsorption are, the more adsorbing power a particular adsorbent is able to exert. The higher the solubility parameter and the solubility parameter polar an~
hydrogen bon~ing components of the solvent utili~ed as the 1 ~56675 vehicle for desorption are, the morç the desorbing power.
- The higher the degree of unsaturation ~and Iodine Value) of the fraction desired to ~e separated is, the higher the solubility parameter and solubility parameter polar and hydrogen bonding components of the solvent that can be used for adsorbing and that is required for desorbing and the higher the ratio of surface-silicon atoms to aluminum atoms and the lower the leYel of cation substituents capable o forming ~ complexes in the adsorbent that can be used for adsorbing and which will allow desorbing.
When a particular adsorben~ has been selected, the solvent used during adsorbing should ha~e a solubility parameter and solu~ilit~ parameter components sufficiently low to obtain selecti~it~, and the solvent used for desorbing should have a solubility parameter and solubility parameter components sufficiently high to obtain ~esorption.
When a particular sol~ent Qr partic~lar $olvents has (have) been selected, an adsorbent is selected with a ratio of surface-silicon atoms to al~minum atoms sufficiently low 20 and a level ~f cation s~stituents capa~le Qf forming ~ ;
complexes sufficiently high to prouide desired selectivity during adsorption and with a ratio of surface-silicon at~ms to aluminum atoms sufficiently high and a level of cation substitu~nts capa~le of forming ~ complexes sui~iently low to allow desorption of all or desired portion of adsorbed triglyceride during the desorbing step.

1 ~56675 We turn now to the conditions of temperature and - pressure for the instant fracti~na~ion prvcess. The temp-eratures utilized during adsorbing and during desorbing generally range Erom about lSC. to about 200~C. A preferred temperature range to be used when the feed is a mixture of triglycerides having fatty acid moieties with aliphatic chains having from 12 to 20 carbon atoms, is 50 to 80C. and temperatures as low as about 40~C. may provic~e an advan~age especially when triunsat~red moiety is present. The pressures utilized during adsor~ing an~ desor~ing can be the same and generally are those pressures encountered in packed bed processin~, e.g., ranging from atmospheric (14.7 psia) to ab~ut S0~ psia. Fqr a simulated m~ving bed process as described hereafter, the pressures utilized preferably range from about 30 psia to about 120 psia or are as prescribed by the desire~ flow rate.
For a batch process, sufficient residence time should be provided to obtain appropriate yields and purities, usually lS min~tes to 20 hour$. The rat~$ for ~ontinuous 2~ processing are a function o~ the size of the equipment, the resol~ing ability Qf the adsorbent-sol~ent pair3 and the desired yield and purity.
The fracti~nation process herein as described abo~e pro~ides a "raffinate" and an "extract". The raffinate 1 ~56675 contains fraction which is enriched in content of trigly-- ceride of lower Iodine ~alue. It comprises triglyceride which was weakly attracted by the adsorbent~ dissolved in solvent. The extract contains fraction enriched in content of triglyceride of higher Iodine ~alue. It comprises triglyceride which was more strongly attracted by the adsorbent, dissolved in soluent. The fractions of trigly-ceride can be recauered from the raffinate and from the extract by con~en~ional separa~ion processes such as by stripping sol~ent with heat, vacuum and/or steam.
We turn now to apparat~s for a one sol~ent process herein and its operati~n.
For batcll processing, the one solYent process herein is readil~ carried ou~ in equipment conventi~nally used for lS adsorptions carried out ~atch-wise. For example, such processing can be carried out u~ilizing a,column containing adsorbent and alternatel~ (a) introducing feed diss~lved in solvent to obtain selecti~e adsorption and ~b) introducing solvent to obtain desorption of adsorbed $raction.
For continuous processing, the one solvent process herein is readil~ carried out in conventional continuous ~.

..

1 ~56675 adsorbing apparatus and is preferably carried out by means of a simulated moving bed unit operation. A simulated moving bed unit operation and apparatus for such useful herein is described in Broughton et al U.S. Patent No.
2,985,589.
For a simulated mo~ing bed embodiment of this invention, preferred apparatus includes: (a) at least four columns connected in series~ each containing a bed of adsorbent; (b) liquid access lines communicating with an inlet line to the first column, with an outlet line from the last column, and with the connecting lines between successive columns; (c) a recirculation loop including a variable speed pump, to provide communication between the outlet line from the last column and the inlet line to the first column; and ~d) means to regulate what flows in or out of each liq~id access line.
Such preferred simulated moving bed apparatus is operated so that liquid flow is in one direction and so that countercurrent flow of adsorbent is simulated by manipulation of what goes into and out of the liquid access lines. In one embodiment, the apparatus is operated so that four functional zones are in operation. The first of the functional zones is usually reerred to as the adsorption zone. This zone is downstream of a feed inflow and upstream of a raffinate outflow. In the adsorption zone, there is a net and selecti~e adsorption of triglyceride of higher Iodine Value and a net desorption of solvent and of trigly-ceride of lower Iodine Value. The second of the functional zones is usuall~ referred to as the purification zone. It ,:

1 ~56675 is downstream of an extrac~ outflow and upstream of the - feed inflow and j~st upstream of the adsorption zone.
In the purification zone, triglyceride of higher Iodine Value which has previously been desorbed is preferentially adsorbed and there is a net desorption of sol~ent and of triglyceride of lower Iodine ~alue. The third o~ the functional zones is referred to as the desorption zone. It is downstream of a solvent inflow and upstream of extract outflow and just upstream of the purification zone. In the desorption zone, there is a net desorption of tri~lyceride of higher Iodine Value and a net adsorption of sol~ent. The fourth functional zone is usually referred to as the buffer zone. It is downstream of the raffinate outflow and upstream of the solvent inflow and just upstream o the desorption zone. In the buffer zone, triglyceride of lower Iodine Value is adsorbed and soluent is desQrbed. The ~ario~s liquid access lines are utilized to pro~ide the feed inflow between the purification and adsorption zones, the raffinate outflow between the adsorption and buffer zones, soluent inflow between the ~ffqr and desorption zones and extract outflow between the desorption an~ purifiçation zones. The liquid flow is manipulated at predetermined time periods and the speed of the pump in the recirculation loop is ~aried con-current with such manipulation so that the inlet points (for feed anc~ solvent) and the outlet pQints (for raffinate and extract) are moved ~ne position in the ~irection of liquid flow (in a downstream direction) thcreb~ mo~ing the aforedescribe~l zones in the direction of liquid flow and simulating countercurrent flow of adsorbent.
In another embodiment of simulated mo~ing bed 1 ~5~675 -35- ;

operation, a plurality of successive desorption zones is utilized (in place of a single desorption zone) with solvent being introduced at the upstream end of each desorption zone and extract being taken ofE at the downstream end of each desorption zone. It may be advantageous to use different solvent inlet temperatures and/or different sol~ents for different desorption zones.
In another embodiment of simulatcd moving bed operation, raffinate is taken off at a plurality of locations along the adsorption zone.
Less preferred continuous simulated moving bed apparatus than described above is the same as the apparatus described above except that the recirculation loop is omitted. The buffer zone can also be qmitted.
In the operaiton of the above described simulated moving bed processes, the relative number of columns in each ~one to optimize a process can be selected based on selectivities and resolution revealed bY pulse testing coupled with capacity and purity requirements. A factor in selecting the number of columns in the adsorption zone is the percen-tage of the feed to be adsorbed. The purity of the extract and raffinate streams is a function of the number of columns in the adsorption zone. The longer the adsorption zone is ~the more columns in it), that is, the further removed the feed inlet is from the raffinate outlet, the purer the raffinate is.
In the operation o the above described simulated moving bed processes, the time interval between manipulations of liquid flow should be sufficient to allow a substantial proportion of triglyceride of higher Iodine Value to stay in the adsorption zQne and a substantial proportion of triglyceride of lower Iodine Value to leave.

1 ~5667~
-We turn now to apparatus for the two solvent process herein and its opera~ion.
Such two solvent process is preferably carried out using a column loaded with adsorbent. The feed and the solvent constituting the adsorption vehicle are run through the column until a desired amount of feed is adsorbed. Then, the desorbing solvent is run through the column to cause desorption of adsorbed material.
Such two sol~ent process is less preferably carried out, for example, in a batch mixing tank containing the adsorbent. The feed together with solvent constituting the adsorption vehicle is added into the tank. Then mixing is carried out until a desired amount of adsorption occurs.
Then liquid is drained. Then desorbing solvent is added and mixing is carried out until the desired amount of desorption occurs. Then solvent containing the desorbed triglyceride is drained.
We turn now in more detail to the important process referred to earlier involving sunflower oil. The feed is refined and bleached sunflower oil; it contains from about 9% to about 12% by weight saturated fatty acid moiety ~palmitic acid moiety and stearic acid moiety) on a methyl ester basis. The adsorbent for this process is that generally described abo~e. Preferably, the adsorbent is one derived from silica gel having a mean pore diameter of at least about 75 angstroms and a surface area of at least about 300 square meters per gram and is further characterized by a ratio of surface-silicon atoms to aluminum atoms ranging from about 3:1 to a~out 10:1, a level of silver cation substituents in a ~alence s~ate of 1 ranging from about 0.10 millimoles/100 square meters of adsorbent surface area to :

1~$6~7~

about 0.35 millimoles~lOO square meters of adsorbent surface area with any remainder of cation substituents being sodium substituents, and a moisture content less than about

4~ by weight. The temperature used during adsorbing and during desorbing preferably ranges from about 50C. to about 80C, The p~ocessing is preferably carried out continuously in a one solvent process in a simulated moving bed unit operation as descri~ed above utilizing a pressure ranging from about 30 psia to about 12Q psia or as prescribed by the desired flow rate. The solvent for a one solvent process is~that generally described above for a one solvent process and preferably comprises ethyl acetate. The extract obtained contains triglyceride mîxture containing less than about 3.5 by weight saturated fatty acid moiety on a fatty methyl ester basis. Product recovered from the ex~ract is s~itable for a salad or cooking oil.
We turn now in more detail to the important process referred to earlier involving soybean oil feed. As indicated earlier the feed is soybean oil ~refined, bleached and deodorized soybean oil) containing from about 6.5~ to abo~t 8.5~ by weight linolenic acid moiety (on a -fatty meth~l ester basis) and having an Iodine Value ranging from about 13n to 150. The adsorbent f~r this process is that generally described above. Preferably, the adsorbent is one derived from silica gel having a mean pore diameter o at least 1 ~5B67~

about 75 angstroms and a surface ~rea of at least about 300 square meters per gram and is f~rther characterized by a ratio of s~rface-silicon atoms to aluminum atoms ranging from about 3:1 to abo~t lp:l, a level of silver cation substituents in a valence state of 1 ranging from about 0.10 millimoles/100 square meters of adsorbent surface area to abou~ 0.35 millimoles/100 s~uare meters of adsorbent surface area with any remainder o~ cation substituents being sodium su~stituents, and a moisture content less than about 4~ ~y weight. The temperature used during adsorbing and during desorbing preferably ranges from about 50C. to a40ut 80C., and temperatures as low as a~o~t 40~C. can sometimes provide an advantage.
The processing is preferably carriad o~t continuously in a one solvent process in a simulated moving bed unit operation as descri~ed above ~tilizing a pressure ranging from about 30 psia to a~out 120 psia ~r as prescribed by the desired flow rate. The solvent for a one sol~ent process is that generally described above for a one solvent process and preferably is ethyl ace-tate or a blend of ethyl acetate and hexane. The raffinate obtained contains triglyceride mixtUre con-taining fr~m 0% to ab~ut 5% linoleni,c acid moiety by weight on a fatty methyl ester basis and ha~ing an Iodine Value ranging Erom abo~ 80 to a~out 125. Prod~ct recovered from the raffinate is competitive with to~ch hardened soybean oil in relation to rancidity and odor problems and avoids entirely the problems associated with touch 1 1S~675 and hydrogenation odor and cis to ~rans isomeriza~ion and - double bond position changes. In other words, the product obtained from the process of the in~ention contains no trans double bonds and no double bonds in positions different from those in the feedstock. Fraction obtained from extract is an excellent drying oil.
We turn now in more detail to the multistage processing referred to generally above.
Multistage processing can in~ol~e the following.
The feedstock to be separated is processed in a first stage to obtain first extract containing fraction enriched ~compared to the feedstock~ in cQntent of triglyceride of higher Iodine ~alue and first rafinate containing fraction enriched (compared to the feedstock) in content of trigly-l$ ceride of lower Iodine Yal~e and depleted (completed to thefeedstock) in cpntent of triglyceride of higher Iodine Value.
The first raffinate or first extract, preferably the tri-glyceride fraction Qbtained by essentially completely removing sol~ent from first raffinate or first extract, is processed in the secon~ stage tQ obtain second extract containing fraction enriched in content of triglyceride of higher Iodine ~alue (compared to the feed to the second stage) and second raffinate enriched (compared to the feed to the second stage) in content Qf triglyceride of lower Iodine ~alue and depleted (compared to the feed to the second stage) in conten~ of triglyceride of higher Iodine :

~ ~L56~7~

Value. To the extent succeeding stages are used, each succeeding stage has as its feed raffinate or extract from the preceding stage, preferably triglycer;de fraction obtained by essentially completely removing solvent from such.
We turn now to ad~antages of the process herein.
Significant aduantages result from the chemical composition and structure of the a~sorbent herein. Firstly, such adsorbent is made from materials which are readily commercially available in large amounts. Secondly, flexibi-lity in adsorbent composition is readily provided in that silica gels with different pore sizes and sur~ace areas are readily available and in that a predetermined ratio of surface-silicon atoms to aluminum atoms is readily obtained.
Thirdly, level of cations capable of forming ~ complexes can be readily regulated by selecting the ratio of surace-silicon atoms to al~minum atoms. Fourthl~, any cations ;~
capable of formi~g ~ complexes are situated at the surface of the adsorbent where such are available to provide adsorbing power thereby providing efficient usage of s~ch cations(e.g. silver).
Furthermore, the process herein is characterized ~y a long adsorbent life cycle. Firstly, there is no problem o cations capable of forming ~ complexes being leached from the adsorben~ as there is with silver nitrate treated silica gel adsorbents. This is because the cations are attached in the adsorbent by electrostatic interaction. Secondly, there is no fouling of the adsorbent with impurities. Thirdly, , ~, ., 1 ~ 5~675 the adsorbent has physical strength such that it does not break down into smaller pieces.
Furthermore, the adsorbent herein is advantageous over crystalline zeolite adsorbents from the standpoints of flexibility and dynamic capacity and is advantageous over resin adsorbents from the standpoints of flexibility~ dynamic capacity, cost, and of bein~ inorganic in nature.
Moreover, processing is carried out without any signifi-cant amount of polymerization so that there is no problem of disposing o~ polymer by-product.
Furthermore, the process herein is carried out without the adsorbent handling and loss problems which can be associated with use of microparticulate particle size adsorbents.
The invention is illustrated in the following specific examples.
In Example I below, a "pulse test" is run to determine the quality of separation that be obtained in one solvent processing with selected adsorbent and solvent. The apparatus consists of a column having a length of 120 cm.
and an inside diameter of 1 cm. and having inlet and outlet ports at its opposite ends. The adsorbent is dispersed in solvent and then introduced into the column. The column is packed with about 100 cc. of adsorbent on a wet packed basis. The column is in a temperature controll~d environment.
A constant flow pump if used to pump liquid through the column at a predetermined flow rate. In the conducting of the test, the adsorbent is allowed to come to equilibrium with the solvent and feed by passing a mixture of the solvent and feed through the column for a predetermined period of time.
The adsorbent is then flushed with solvent until a 5 milli-liter fraction contains a negligible amount of feed. At 1 1~6675 this time, a pulse of feed containing a known amount of docosane tracer is injected, via a sample coil, into the solvent inflow. The pulse of feed plus tracer is thereby caused to flow through the column with components first being adsorbed by the adsorbent and then caused to be desorbed by the solvent. Equal volume ef1uent samples are collected, and triglyceride therefrom is converted to methyl ester which is analyzed by gas chromatography. From these analyses, elution concentration curves for tracer and tri~lyceride components are obtained ~concentration in milligrams per milliliter is plotted on the y axis and elution volume in milliliters is plotted on the x axis). The dlstance from time zero (the time when the pulse of feed plu~ tracer is introduced) to the peak of a curve is the elution volume.
The difference between the elution volume for a triglyceride component and the elution volume for ~he tracer is the retention volume of that triglyceride component. The relative selectiuity of one triglyceride component o~er another is the ratio of their respective retention ~olumes.
In Examples II-I~, pilot plant test apparatus ~sometimes referred to as a demonstration unit) is utilized. The apparatus is operated according to the continuous simulated moving bed unit opcration mentioned above to carry out a one solvent process. The apparatus comprises columns which are connected in series in a loop to permit the process liquid to flow in one direction. Each column has a length of 24 inches and an inside diameter of 9/10 of an inch and is loaded with about 237 cc. of adsorbent (wet packed basis).

.
. . . . .

1 ~5~675 Each column is equipped with four-position valves (top and bottom) connected to four inlet and four outlet conduits.
When a valve is closed, liquid flows only toward the column downstream of the valve. By selecting between the eight open positions (four at top and four at bottom), feed can be caused to be introduced to the system (e.g. position 1), solvent can be caused to be introduced to the system (e.g.
position 2), a raffinate stream can be removed from the system (e.g. position 3), an e~tract stream can be removed from the sys~em (e.g. position 4) or a solvent stream can be removed from the system ~e.g. position 5). ~ackflow check positions are located in each of the bottom valves.
These are used to isolate zones of the system from backflow;
i.e., isolate the high pressure inlet (solvent) from the low pressure outlet. Operation is as follows: At any time, the apparatus constit~tes a single stage. It is operated with four working zones (adsorption, purificati~n, desorption, and buffer). One backflow control valve is always in closed position to eliminate backflow between the solvent inlet and the low pressure outlet. No recirculation is used. The columns are apportioned between the adsorption, purification, de-sorption, and buffer zones with a selected number of columns in series comprising each zone. ~eed is introduced into the first column of the adsorption zone and is dissolved in solvent and is contacted with adsorbent. As liquid flows downstream through the adsorption zone, triglyceride component(s) of higher Iodine Value is (are) selectively 5667~

adsorbed leaving raffinate enriched in triglyceride of lower Iodine Value. In the purification zone, non-adsorbed components are forced from the adsorbent and are thus forced downstream toward the feed point. The extract is removed at the inlet to the purification zone and is enriched in adsorbed components. The solvent is added at the inlet to the desorption zone and causes desorption of adsorbed component(s) from the adsorbent for removal downstream at the extract point. In the buffer zone, triglyceride is adsorbed and solvent is desorbed. A stream denoted herein as a solven~ outlet stream and consisting mostly of solvent is taken off at the outlet from the buffer zone. At selected intervals a controller advances the flow pattern (into and out of columns) one column (in other words, the controller mani-pulates valves so that raffinate outflow, feed inflow~ extractoutflow, solvent inflow and solvent outflow points each advance one step, that is, to the next liquid access point in the direction of liquid flow) to "step forward'!' to keep pace with the liquid flow. A cycle consists Qf the number of steps equal to the number o columns. The "step time" is chosen such as to allow the non-adsorbed components to advance faster than the feed point and ~each the raffinate point. The adsorbed triglyceride moves slower than the feed point and falls behind to the extract point.
In Example V below, apparatus and operation are generally as described above for Examples II-IV except that no b~ffer zone is used and there is no solvent outlet stream.

1 ~5~67~

In Example VI below, apparatus and operation are generally as described above for example II-I~ except that two desorption zones are used, one following the other, with solvent being introduced at the upstream end of each desorption zone and extract being removed at the downstrcam end of each desorption zone. Thus, Example VI is operated with five working zones ~i.e~ an àdsorption zone, a purifi-cation zone, a first desorption zone, a second desorption zone and a buffer zone) and with seven str~ams (a feed intro-duction stream at the upstream end of the adsorption zone,a raffinate outlet stream at the downstream end of the adSOrption zone, a solvent outlet stream at the downstream end of the buffer zone, a first solvent inlet stream at the upstream end of the first desorption zone, a first extract outlet stream at the downstream end of the first desorption zone, a second solvent inlet stream at the upstream end of the second desorption zone, and a second extract outlet stream at the downstream end of the second desorption zone).
In Example ~II below, a test is run to demonstrate selection of solvents for a two solvent process once a particular adsorbent has been selected. The apparatus utilized is the same as that utilized in the run of Bxample I, and as in Example I, the column is packed with about 100 cc. of adsorbent twet packed basis). The following procedure is utilized. A plurality o solvents is utilized successively, each being of progressively increasing desorbing power. The initial solvent is pumped through the column at 5 ml~minute with the column temperature being 50C.
2.0 gms of feed (0.1 gram docosane tracer and 1.9 gms tri-glyceride mixture) is dissolved in lO ml. of the initial solvent. Plow through the column is s~opped, and the 10 ml.
of initial solvent with feed dissolved therein is injected into the column entrance. Flow of initial solvent is then restarted and effluent sample collection is begun. After approximately two column volumes of the initial solvent is pumped into the column~ the solvent is changed and approx-imately two column volumes o~ the second solvent is pumpedinto the column. The solvent is successively changed after two column volumes of a solvent is pumped until all the solvents being tested have been pumped into the column.
Eluant samples are collected, and the triglyceride therefrom is converted to methyl ester which is analyzed ~y gas chromatography.
We turn now to the Examples I-VIII which are generally described above.
EXA~PL~ I
The "pulse" consists of 0.5 ml solvent and 0.5 ml of triglyceride plus tracer. The triglyceride plus ~racer consists by weight of 45~ triolein, 45~ trilinolein and lO~ docosane tracer. The "pulse" is free of impurities which can foul the adsorbent.
The adsorbent has the following characteristics: It is derived from silica ~el having a mean pore diameter of approximately lO0 angstroms and a surface area of 346 square meters per gram. It is further characterized by a ratio of surface-silicon atoms to aluminum atoms of 6.4:1, a :

1 ~ SB675 -~7-moisture content less than 2% by weight~ and a particle size o~ 35-70 mesh (U.S. Sieve Series). It contains sodium substituents as all of its cation substituents.
The adsorbent is made as ~ollows: Silica Gel 100 (35-70 mesh U.S. Sieue Series) is utilized. 1000 grams of the silica gel and 2 liters o~ distilled water are charged into a 5.0 liter, 3-neck~ fluted flash fitted with a mechan-ical s~irrer, a pH electrode, and an addition funnel. The mixture is agitated to fQrm a homogeneous slurry. The pH
of the slurry is adjusted to 9.$ with 10~ aqueo~s sodium hydroxide solutiQn. Then, a freshly prepared solution of sodium aluminate (108.6 gm) in distilled water (2.0 liters) is added. The slurry is stirred lQ hours a~ room temperature tabout 20C.). Then stirring is stopped and the mixture is allowed to stand overnight. The resulting product is poured into a glass chromatographic column and washed free of un-reacted al~minate with distille~ water (1-2ml per minute).
Washing is continued until the pH of the effluent is about 9Ø The solid is suction filtered to remove bulk water and then dried in a forced-draft o~en (105-110C.) overnight.
The solvent c~nsists b~ Yolume of 80% hexane and 20~
ethyl acetate. For this solvent blend: ~ =7 43~ ~d = 7.38, ~p = 0.52 and ~H = 0 70 In the run, solvent is pumped continuously through the column at a rate of 6.2 ml per minute. At time zero, the sample pulse as described above is introduced by means of the sample coil into the soluen~ flow. The e~ual uolume 1 ~5~7~
, samples that are collected are each 6.2 ml (one sample per minute).
The run is carried out at S0C.
Retention volumes are obtained as fQllows: for triolein, 12.40 ml; for trilinolein, 18.60 ml.
The relative selecti~ity for trilinolein/ triolein is 1.50.
The abo~e indicates separation on the basis of Iodine Value.
At the peak for trilinolein in the elution concentration curve, the percent purity is 68~ trilinolein. This indicates resolution such tha~ ~he use Qf multiple stages with the tested solvent and ads~r~en~ combination in continuous simulated mo~ing bed processing would be preferred and further indicates that silvered adsorbent would more appro-priately be ~lsed.
EXAMP~E II
.. , ~ .. . .
This example illustrates separation of soybean oil triglycerides into raffinate fraction con~aining a reduced 20 percentage of triglyceride with linolenic acid moiety and -an extract frac~ion. The run of this exam~le is carried out utilizing continuous simulated mo~ing bed processing.
The feed composition is refine~, ~leached and deodorized soybean oil. I~ contains by weight ~n a methyl ester basis 10.03~ methyl palmitatq~ 4.08~ methyl stearate, 24.62~ methyl oleate, 54.73% methyl lin~leate, and 6.54~ methyl linolenate.
It has an Iodine ~alue of 13~.10. It is free of impurities which can foul the adsorbent.
The adsorbent has the following characteristics: It is derived from silica gel ha~ing a mean pore diameter of approximately 100 angstroms and a surface area of 346 square meters per gram. It is also characterized by a ratio of suTface-silicon atoms to aluminum atoms of 6.4:1, a moisture content less than 2% by weight, and a particle size of 35-50 mesh ~U.S. Sieve Series). It contains 0.27 millimoles of silver ~in the form of cation substi~uents in a valence state of 1) per 100 square meters of adsorbent surface area. The silver su~stitul3nts make up 67.6% of the exchangeable cations.
The remainder of the exchangeable cations are sodium substituents. The surface area of the final adsorbellt is 233 square meters per gram.
The adsorbent is made as follo~s: Silica Gèl 100 is screened to provide a fraction of 35-50 mesh particle size.
1000 grams of such fraction and 2 liters of distilled water are charged into a S.0 liter, 3-neck, fluted flask fitted with a mechanical stirrer, a pH electrode, and an addition funnel. The mixture is agitated to form a homogeous slurry.
The pH of the slurry is adjusted to 9.5 with 10% aqueous sodium hydroxide solution. Then a freshly prepared solution of sodium aluminate (108.6 gm) in distilled water (2.0 liters) is added. The slurry is stirred 10 hours at room temperature (about 20C.). Then stirring is stopped and the mixture is allowed to stand overnight. The resulting product is trans-ferred to a reaction vessel, and a solution of silver nitrate 1 1S6~7$

- 5 o -(156 gms) in distilled water is added. This mixture is - stirred for 10-20 minutes and left standing overnight at room temperature. The exchange liquor is then removed by suction filtration and the solid is washed until wash effluent S contains no detectable silver ion. Dewatering and drying is carried out by filtering to remo~e ~ulk water and drying in a forced-draft oven (105-llOaC.) overnight.
The solvcnt consists by volume of 100% ethyl acetate ( ~= 8.85, ~= 7.70, ~p = 2.60, and ~ = 3.50).
The controller and the valves of the demonstration unit are set so that the adsorption zone includes eight columns, the purification zone includes eight columns, the desorption zone includes 6 columns and the b~ffer zone includes two columns (total columns =24).
The step time (the interval at which the flow pattern is advanced one column) is 7 minutes.'' The feed rate is 1.7$ ml. per minute. The solvent introduction rate is 47.~0 ml. per minute. The extract flow rate is 18.75 ml. per minute. The raffinate flow rate is 17.00 ml. per minute. The s~lvent ,outlet flow rate (at the exit of the buffer zone) is 1~.00 ml. per min~te.
The temperat~re of operation is 40~.
Raffinate, extract, and solvent outlet streams are recovere~. $eparation is o4tained on the ~asis of Iodine Value.
Triglyceride fraction in the extract contains by weight (on a methyl ester basis) ~.6~% meth~l palmi~ate, 0.80%

r .~

1 ~5~675 methyl stearate, 14.28% methyl oleate, 63.53% methyl lino-leate, and 17.70% methyl linolenate.
Triglyceride fraction in the raffinate contains by weight ~on a mcthyl ester basis) 12.29% me~hyl palmitate, 5.24~ methyl stearate, 28.30~ methyl oleate7 51.70~ methyl linoleate, and 2.47% methyl linolenate and has an Iodine Value of about 125. The product is suitable for use as a liquid shortening or as a salad or cooking oil. The product contains no trans double bonds and no double bonds in posi-tions different from those in the feedstock. The triglyceridein the raffinate consists of about 75~ of that in the feed-stock.
Processing is carried out without any significant amount of polymerization.
There is no significant leaching of silver. There is no fouling of the adsorbent with impurities.
The adsorbent particle size does not result in any significant handling ~r loss problems.
When Zeolite X or Zeolite Y or silvered Zeolite X or silvered Zeolite Y is substituted for the adsorbent in the run of Example II, essentially no fractionation on the basis of Iodine Value is obtained. This is due at least in part to inferior dynamic capacity.
EXAMPLE III
This example illustrates separation of triglycerides into extract fraction containing a substantially reduced percentage of triglyceridc with saturated fatty acid moiety and a raffinate fraction. The run is carried out utilizing continuous simulated moving bed processing.
The feed composition is refined, bleached and deodorized sunflower oil. It contains by weight ~on a methyl ester basis) 6.61% methyl palmitate, 3.73~ methyl stearate, 23.96 ~ . ~

1 ~56~5 methyl oleate and 65.7Q% methyl linoleate. It is essentially free of impurities which can foul the adsorbent.
The adsorbent is the same as that used in Example II.
The solvent consists by volume of 100~ ethyl acetate l ~ 8.85, ~D= 7 70, ~p=2.60, ~=3.50).
The controller and the valves of the demonstration unit are set so that the adsorption zone includes three columns, the purification zone includes eight columns, the desorption zone includes three columns and the buffer zone includes one column (total columns = 12).
The step time (the interval at which the flow pattern is advanced one column) is 7.00 minutes.
The feed rate is 2.0 ml~ per minute. The solvent introduction rate is 41.50 ml. per minute. The ~act flow rate is 13.25 ml. per minute. The raffinate flow rate is 17.00 ml. per minute. The solvent outlet flow rate ~at the exit of the buffer zone) is 13.25 ml. per minute.
The temperature of operation is 50C. ``
Separation is obtained on the basis of Iodine Value, i.e., to obtain fractions of higher Iodine Value and of lower Iodine Value.
Triglyceride fraction in the raffinate contains by weight ~on a methyl ester basis) 8.65% methyl palmitate, 4.75~ methyl stearate, 28.45~ methyl oleate and S8.15%
methyl linoleate.
Triglyceride fraction in the extract contains by weight (on a methyl ester basis) 2.2Q~ methyl palmitate, 0.84~ methyl stearate, 14.28~ methyl oleate, and 82.58% methyl linoleate.
It is suitable for use as a s~lad or cooking oil.

- 1~5~675 .

Processing is carried out without any significant amount of polymerization.
There is no significant leaching of silver. There is no fouling of the adsorbent with impurities.
The adsorbent particle size does not result in any significant handling or loss problems.
When in the run of Example III, the adsorbent is derived from Grade 59 Silica Gel (mean pore diameter of approximately 75 angstroms and a surface area of 470 square meters per gram) instead of Silica Gel 100, extract triglyceride fraction is obtained containing less than 3.5~ by weight saturated fatty acid moiety (on a fatty methyl ester basis).
When in the run of Example III, an equivalent amount of copper or platinum or palladium is substituted for the silver substituents of the adsorbent, results are obtained indicating attainment of fractionation on the basis of Iodine Value.
When in the run of Example III, an equivalent amount of potassium, barium, calcium, magnesium or zinc sub-stituents is substituted for the sodium substituents of the adsorbent, results are obtained indicating fraction-ation on the basis of Iodine Value.
When Amberlyst ~ XN1010 (a macroreticular strong acid cation exchange resin sold by Rohm & ~Iaas) with an equivalent amount of silver to that used in Example III is substituted for the adsorbent in the run of - ~15~675 Example III, the fractionation obtained is significantly less complete (the extract triglyceride fraction contains more than 3.5~ by weight saturated fatty acid moiety on a fatty methyl ester basis).
When Zeolite X or Ze~lite Y or siluered Zeolite X or silvered Zeolite Y is substit~ted for the adsorbent in the run of Example III, essentially no fractionation on the basis of Iodine ~alue is obtained. This is due at least in part to inferior dynamic capaçity.
EXAMP~E I~
~ ~ ... ..
This example illustrates separation ~f triglycerides into extract fractiQn containing a substantially reduced `
percentage of triglyceride with saturated fatty acid moiety and a raffinate fraction. The run is carried out utilizing continuous simulated mo~ing bed processing.
The feed composition is refined, bleached and deodoriz~d sunflower oil. It contains ~y wcight (on a methyl ester basis) 6.37~ methyl palmitate, 4.45~ methyl stearate, 17.26~
methyl olcate and 71.92~ methyl linoleate.; It is essentially free Qf impurities which can f~ul the adsorbent.
The adsorbent has the following charac~eristics: It is derived from silica gel ha~ing a mean pore diameter of approximately 100 an~stroms and a surface area o 346 square meters per gram. It ~s also characterized by a ratio of surface-silicon atoms to aluminum atoms of 11.4:1, a moisture content less than 2~ by weight, and a particle size of 35-50 mesh (U.S. Sie~e Series). I~ contains Q.13 millimoles of sil~er (in ~he form of cation substituents in a ~alence state of 1) per lOQ square meters of ads~rbent s~rface area.

~ ~56~75 The silver substituents make up 78.3~ of the exchangeable cations. The remainder of the exchangeable cations are sodium substituents. The surface area of the final adsorbent is 245 square meters per gram.
The adsorbent is made as follows: Silica Gel 100 is screened to provide a fraction of 3S-50 mesh particle size.
1000 grams of such fraction and 2 liters of distilled water are charged into a 5.0 liter 9 3-neck, fluted flask fitted with a mechanical stirrer, a pH electrode, and an addition funnel. The mixture is agitated to form a homogeneous slurry.
The pH of the slurry is adjusted to 9.5 with 10~ aqueous sodium hydroxide solution. Then a freshly prepared solution of sodium aluminate (43.4 gm) in distilled water (2.0 liters) is added. lhe slurry is stirred 10 hours at room temperature (about 2~C.). Then stirring is stopped and the mixture is allowed to stand overnight. The resulting product is trans-~erred to a reaction uessel, and a solution of silver nitrate (82.8 gms) in distilled water is added. This mixture is stirred for 10-20 min~tes and left stan;ding ovcrnight at room temperature. The exchange liquor is then removed by suction filtration and the solid is washed until wash effluent contains no detectable silver ion. ~ewatering and drying is carried out by filtering to remove bulk water and drying in a force-draft ~ven (105-llPC.) overnight.
The solvent consists by volume of 60~ hexane and 40~ ethyl acetate. For this solvent ~lend: ~ = 7.65, 1 ~S667~

~D = 7.46, ~p = 1.04, ~H = 1.4 The controller and the valves of the demonstration unit are set so that the adsorption zone includes eight columns, the purification zone includes eight columns, the desorption zone includes 6 columns and the buffer zone includes two columns (total columns =24).
The step time (the interval at which the flow pattern is advanced one column) is 6 minutes.
The feed rate is 1.00 ml. per minute. The solvent introduction rate is 51.50 ml. per minute. The extract flow rate is 12.70 ml. per minute. The raffinate flow rate is 20.30 ml. per minute. The solvent outflow flow rate (at the exit of the buffer zone) is 19.50 ml. per minute.
The temperatur~ of operation is 50C.
Raffinate, ex~ract, and solvent outlet streams are recovered. Separation is obtained on the basis of Iodine Value, i.e., to obtain fractions of higher Iodine Value and of lower Iodine Value.
Triglyceride fraction in the raffinate contains by weight (on a methyl ester basis) 8 40% methyl palmitate,

6.31~ methyl stearate, 21.53~ methyl oleate and 63.76 methyl linoleate.
Triglyceride fraction in the extract contains by weight (on a methyl ester basis) 0.55~ methyl palmitate, 0.32~ methyl stearate, 7.42~ methyl oleate, and 91.71~ methyl linoleate.
lt is suitable for use as a salad or cooking oil.
Processing is carried out without any significant 1 ~5~675 amount of polymerization.
There is no significant leaching of silver. There is no fouling of the adsorbent with impurities.
The adsorbent particle size does not result in any significant handling or loss problems.
When a solvent consisting by volume of 70~ hexane and 30~ acetone (for this solvent blend: ~ = 7.62, ~D = 7 ~9' ~p = 1.53, ~H = 1.02) is substituted in Example IV for the hexane/ethyl aceta~e solvent, fractionation on the basis of Iodine Value is obtained.
When a solvent consisting by vclume of 100~ diethyl ether ~ ~- 7.65, ~D = 7.1, ~p = 1.4, ~H = 2.5) is substituted in Example IV for the hexane~ethyl acetate solvent, frac- ;
tionation on the basis of Iodine Value is obtained~
When a solvent consisting by volume of 17.5~ ethanol and 82.5~ hexane ~for this solvent blend: ~~ 7 70~ ~D = 7.48, ~p = 6.75, ~H = 1.66) is substituted in Examplq IV for the hexane/ethyl acetate solvent, fractionation on the basis of Iodine Value is attained.
2~ When Amberlyst XN1010 (a macroreticular strong acid cation exchange resin sold by Rohm & Haas~ with an equivalent amount of silver to that used in Example IV is substituted for the adsorbent in the run of Example I~, the fractionation ob~ained is significantly less complete (the extract tri-glyceride fraction contains more than 3.5~ by weight saturated fatty acid moiety on a fatty methyl ester basis).
When Zeolite X or Zeolite Y or silvered Zeolite X or silvered Zeolite Y is substituted for the adsorbent in the ~ 1 ~S~67~

run of Example IV~ essentially no fractiona~ion on the basis of Iodine Value is obtained. This is due at least in part to inferior dynamic capacity.
.
EXAMPLE V
. .
This example illustrates separation of triglycerides into extract fraction containing a substantially reduced percentage of triglycerlde with saturated fatty acid moiety and a raffinate fraction. The run is carried out utilizing continuous simulated moving bed processing.
The feed composition contains by weight ( on a methyl ester basis) 5.66~ methyl palmitate plus methyl stearate, 14.00% methyl oleate and 80.34~ methyl linoleate. It is essentially free of impurities which can foul the adsorbent.
The adsorbent has the following characteristics: It is derived from silica gel having a mean pore diameter of approx-imately 100 angstroms and a surface area o 346 square meters per gram. It is also characterized by a ratio of surface-silicon atoms to aluminum atom;s of 10.7:1, a moisture content less than 2~ by weight, and a particle size of 35-S0 mesh ~U.S. Sieve Series). It-contains 0.19 millimoles of silver ~in the form of cation substituents in a valence state of 1) per 100 square meters of adsorbent surface area. The silver substituents make up 89.2~ of the exchangeable cations. The remainder of the exchangeable cations are sodium substituents.
The surface area of the final adsorbe~t is 277 square meters per gram.
The adsorbent is made up the same as the adsorbent of Example IV except that 58 gms of sodium aluminate is used ~SB~75 in the surface alumination reaction and 148 gms of silver nitrate is used in the silvering procedure.
The solvent consists by volume of 100~ ethyl acetate ( ~= 8.85, ~D = 7 70~ ~p = 2.60, and ~H = 3 50) The controller and the valves of the demonstration unit are set so that the adsorption zone includes three columns, the purification zQne includes six columns, and the desorption zone includes three columns (total columns = 12).
The step time (the interval at which the flow pattern is advanced one column) is 6.90 minutes.
The feed rate is 1.50 ml. per minute. The solvent introduction rate is S0.30 ml. per minute. The extract flow rate is 21.80 ml. per minute. The raffinate flow rate is 3U.00 ml. per minute.
The temperature of operation is 5UC.
Raffinate and extract streams are recovered. Separation is obtained on the basis of Iodine Value, i.e., to obtain fractions of higher Iodine Value and of lower Iodine Value.
Triglyceride fraction in the raffinate contains by weight ~on a methyl ester basis) 13.54~ methyl palmitate plus methyl stearate, 17.03~ methyl oleate and 69.43 methyl ~inolaate).
Triglyceride fraction in the extract contains by weight ~on a methyl ester basis) 1.41~ methyl palmitate plus methyl stearate, 12.25~ methyl oleate, and 86.34~ methyl linoleate.
It is suitable for ~se as a salad or cooking oil.

1~56675 Processing is carried out without any significant amount ~of polymerization.
There is no significant leaching of silver. There is no fouling of the adsorbent with impurities.
The adsorbent particle size does not result in any significant handling or loss problems.
When Amberlyst XN1010 (a macroreticular strong acid cation exchange resin sold by Rohm ~ Haas) with an equivalent amount of silver to that used in Example V is substituted for the adsorben~ in Bxample V, separation is significantly less complete.
When Zeolite X or Zeolite Y or silvered Zeolite X or silvered Zeolite Y is substituted for the adsorbent in the run of Example V, essentially no fractionation on the basis lS of Iodine Value is obtained. This is due at least in part to inferior dynamic capaçity.
EXAMPLE VI
This example illustrates separation of triglycerides into two extract fractions each containing a substantlally reduced percentage of triglyceride with saturated fatty acid moiety and a raffinate fraction. The run is carried out utilizing continuous simulated moving bed processing with two successive desorption zones.
The feed composition is refined, bleached and deodorized sunflower oil. It contains by weight (on a methyl ester basis) 10.33~ methyl palmitate plus methyl stearate, 23.96~ methyl oleate, and 65.71~ methyl linoleate. It is essentially free of impurities which can foul the adsorbent.
The adsorbent is the same as tha~ used in Example II.

1 ~56~75 - " -61 -The solvent for each of the two solvent inlet streams is the same and consists by volume of 100% ethyl acetate ( 3= 8.8S, ~D = 7 7~, ~p = 2.60, and ~H = 3 50) The controller and the ~alves of the demonstration unit are set so that the adsorption zone includes 2 columns, the buffer zone includes 1 column, the first desorption zone includes 3 columns, the second desorption z~ne includes 1 column and the purification zone includes S columns (total columns = 12).
1~ The step timç (the inter~al at which the flow pattern is advanced one col~mn) is 6.9 minutes.
The temperature of operation is soQc. except that the solvent inlet stream into the upstream end of the first desorption zone is at 70C.
The feed rate is 2.00 ml per minu-te. The solvent introduction rate in~o the first desorption zone is 45.00 ml per minute. The sol~ent introduction rate into the second desorption zone is 33.25 ml per minute. The first extract flow rate is 45.00 ml per minute. The second extract flow rate is S.00 ml per minute. The raffinate flow rate is 17.00 ml per minute. The solvent outlet flow rate (at the downstream end of the buffer zone~ is 13.25 ml per minute.
Raffinate, first extrac~ second extract and solvent outlet streams are recovered. Separation is obtained on the basis of lodine Value, i.e., to obtain fractions of higher Iodine Value and of lower Iodine Value.
Triglyceride fracti~n in the first extract contains by weight ~on a me~hyl ester basis) 1.95% methyl palmitate plus 3~ methyl stearate, 7.~5% me~hyl oleate and 90.~0% methyl linoleate. It is suitable for use as a salad or cooking oil.

V~sr ~ ~ SB675 Triglyceride fraction in the second extract contains by wei~ht (on a methyl ester basis) 4.65% methyl palmitate plus methyl stearate, 16.95% methyl oleate and 78.40%
methyl linoleate. It is suitable for use as a salad or cooking oil and contains a reduced percenta~e of saturates compared to the feed and an increased percentage of polyunsaturated moiety compared to the feed but a lesser percentage of polyunsaturated moiety than if a single desorption zone were used.
Triglyceride fraction in the raffinate contains by weight (on a methyl ester basis) 11.0% methyl palmitate plus methyl stearate, 23.50~ methyl oleate and 65.50%
methyl linoleate.
Triglyceride fraction in the solvent outlet stream contains by weight (on a methyl ester basis) 3.35~ methyl palmitate plus methyl stearate, 10.73% methyl oleate, and 85.92% methyl linoleate.
Processing is carried out without any significant amount of polymerization.
There is no significant leaching of silver. There is no fouling of the adsorbent with impurities.
The adsorbent particle size does not result in any significant handling or loss problems.
The use of two desorption zoneR instead of one allows better control of the relative amounts of saturated moiety and polyunsaturated moiety in product obtained from an extract stream.
When Zeolite X or Zeolite Y or silvered Zeolite X
or silvered Zeolite Y is substituted for the adsorbent in the run of Example VI, essentially no fractionation on the basis of Iodine Value is obtained. This is due at least in part to inferior d~namic capacity.

1 ~L5~67~

EXAMPLE_VII
The triglyceride mixture for fractionation contains by weight 15.78~ trisaturated triglyceride (containing palmitic acid and stearic acid moieties~, 42.11~o triolein, and 42.11% trilinolein.
The adsorbent used has the following characteristics:
It is derived from silica gel having a mean pore diameter of approximately 75 angstroms and a surface area of 470 square meters per gram. It is also characterized by a ratio of surface-silicon atoms to aluminum atoms of 4.97:1, a moisture content less than 2% by weight, and a particle size of 35-70 mesh (U.S. Sieve Series). It contains 0.33 millimoles of silver (in the form of cation substituents in a valence state of 1) per 100 square meters of adsorbent surface area. The silver substituents make up 97.6% of the exchangeable cations.
The remainder of the exchangeable cations are sodium substituents. The surface area of the final adsorbent is 366 square meters per gram.
Such adsorbent is made as follows: Grade 59 Silica Gel (3-8 mesh U.S. Sieve Series) is gently crushed, and a fraction with particle size range of 35-70 mesh is recovered. 1000 grams of such fraction and 2 liters of distilled water are charged into a 5.0 liter, 3-neck, fluted flask fitted with a mechanical stirrer, a pH electrode and an addition ~unnel.
The mixture is agitated to form a homogeneous slurry. The pH of the solution is adjusted to 9.5 with 10% aqueous sodium hydroxide solution. Then a freshly prepared solution of sodium aluminate (112.2gm) in distilled water (2.0 liters) ~ ~L56675 is added. The slurry is stirred 10 hours at room temperature (about 20 C~). Then stirring is stopped and the mixture is allowed to stand overnight. The resulting product is poured into a glass chromatographic column and washed free 5 of unreacted aluminate with distilled water (1-2ml. per minute). Then, the material in the column is treated with a solution of silver nitrate (a two-fold molar equivalent of silver based on the aluminate reagent) in distilled water.
Flow rate of the silver exchange solution is about 0.5 ml./
10 minute. The solid is then washed with distilled water to remove excess silver nitrate, suction filtered to remove bulk water, and dried in a forced-draft oven (105-110C.) overnight.
The solvent used first consists by volume of 100~
15 hexane ( ~= 7-30, ~D = 7 30' P = ' H = ); this solvent is denoted Solvent I below. The solvent used second consists by volume of 90~ hexane and 10~ ethyl acetate ( for this -solvent blend: ~ r 7-35, ~D = 7 34~ p = 0.25, and ~H = 0 35);
this solvent is denoted Solvent II below. The solvent used 20 third consists by volume of S0~ hexane and 50% ethyl ~cetate (for this solvent blend: ~ =7.81, ~D = 7 50~ ôp = 1.30, ~H = 1.75); this solvent is denoted Solvent III below. The solvent used fourth consists by volume of 100~ ethyl acetate ( ô= 8.85, ~D = 7 70~ ~p = 2.60, H =3 50); this solvent is 25 denoted Solvent IV below. The solvent used fifth consists by volume of 100~ methanol ( ~= 14.5, D = 7 4, ôp = 6.0, ~H = 10.9); this solvent is denoted Solvent V below.
The ~est is carried out at 50C.
Solvent I is pumped through the "pulse test" column 30 described above at 5.0 ml./minute. With flow stopped, a ~15~67~

"pulse" containing 2.0 grams ~95~ triglyceride mixture described abo~e and 5~ C22 linear hydrocarbon tracer) ,~
dissolved in 10 ml. of Solvent I is injected into the column entrance. Flow of Solvent I is then restarted, and eluant sample collection begins. After approximately two column volumes of $olvent I arc pumpcd, the solvent is changed to Solvent II, then to Soluent III, etc. with approximately two column ~olumes of each solvent being pumped in succession after the above described feed injection. Eluant samples are collected. Triglyceride mixture in each collected sample is converted to methyl ester which is analyzed by gas chromatography.
The table below presents the data for this run. In the table: "$3" stands for trisaturated triglyceride, "M3"
stands for triolein, and "~3" stands for trilinolein. The values given opposite each solven~ represent the triglyceride composition eluted with that particular sol~ent. "IV" in the table belQw stands for the calculated Iodine Value of an eluted composition.
TABLE
SEPARATION OF TRIGLYCERIVE MIXTURE
IN A TWO SOLVENT PROCESS
_ Solvent S3 ~ M3 ~ ~3 IV

25II 30.77 56.56 12.67 85.62 III 4.13 34.13 61.74 199.88 IV 0.98 11.97 87.05 249.29 V 0.40 8.68 ~0.92 257.83 1 ~ 5~75 The above data indicates that with the selected adsorbent, to provide one fraction enriched in saturates (S3) and second fraction enriched in unsaturates (M3 and D3), the solvent constituting the adsorption vehicle would contain between 9~ and 100~ hexane with the remainder being ethyl acetate and the solvent constituting the desorbent would be 100% ethyl acetate. Another way of obtaining ~raction enriched in saturates would be to use 100% hexane as the adsorbing solvent and desorbent consisting by volume of 95 hexane and 5% ethyl acetate.
In the test of Example VII, separation on the basis of Iodine Value is obtained, i.e., to produce fractions of higher Iodine Value and of lower Iodinc Value.
Processing is carried out without any significant amount of polymerization.
There is no significant leaching of silver. There is no fouling o-f the adsorbent with impurities.
The adsorbent particle size does not result in any significant handling or loss problems.
Other solvents and blends can be substituted in the above example to provide similar results provided there is similarity of solubility parameter and solubility parameter components.
While the foregoing describes certain preferred embodi-ments of the invention, modifications will be readily apparent to those skilled in the art. Thus, the scope of the invention is intended to be defined by the following claims.

~ .
.~

Claims (17)

The embodiments of the invention in which an exclusive property or privilieg is claimed are defined as follows:

1. A process -for separating a mixture of triglycerides with different Iodine Values and having their carboxylic acid moieties containing from 6 to 26 carbon atoms, to produce fractions of higher Iodine Value and lower Iodine Value, said process comprising the steps of (a) contacting a solution of said mixture in solvent with surface aluminated silica gel adsorbent to selectively adsorb triglyceride of higher Iodine Value and to leave in solution a fraction of said mixture enriched in content of triglyceride of lower Iodine Value, (b) Removing solution of fraction enriched in content of triglyceride of lower Iodine Value from contact with adorbent which has selectively adsorbed tri-glyceride of higher Iodine Value, (c) contacting adsorbent which has selectively adsorbed triglyceride of higher Iodine Value with solvent to cause desorption of adsorbed triglyceride and provide a solution in solvent of fraction enriched in content of triglyceride of higher Iodine Value, (d) removing solution of fraction enriched in content of triglyceride of higher Iodine Value from contact with adsorbent;
said mixture of triglycerides being essentially free of impurities which can foul the adsorbent; the solvent in step (a) and the solvent in step (c) having the same composition or different compositions and being character-ized by a solubility parameter (on a 25°C. basis) ranging from about 7.0 to about 15.0, a solubility parameter dis-persion component (on a 25°C. basis) ranging from about 7.0 to about 9.0, a solubility parameter polar component (on a 25°C basis) ranging from 0 to about 6.0 and a solubility parameter hydrogen bonding component (on a 25°C. basis) ranging from 0 to about 11.5; said adsorbent being derived from silica gel having a mean pore diameter of at least about 75 angstroms and a surface area of at least about 100 square meters per gram; said adsorbent being further characterized by a ratio of surface-silicon atoms to aluminum atoms ranging from about 3:1 to about 20:1, a moisture content less than about 10% by weight, and a particle size ranginy from about 200 mesh to about 20 mesh; said adsorbent having cation substituents selected from the group consisting of cation substituents capable of forming .pi. complexes and cations substituents not capable of forming .pi. complexes and combinations of these; the solvent in step (a) and the solvent in step (c) and the ratio of surface-silicon atoms to aluminum atoms in the adsorbent and the level of cation substituents capable of forming .pi. complexes being selected to provide selectivity in step (a) and desorption in step (c).

2. A process as recited in claim 1 in which the cation substituents capable of forming .pi. complexes are selected from the group consisting of silver, copper, platinum and palladium cation substituents and combin-ations of these, and in which the cation substituents not capable of forming .pi. complexes are selected from the group consisting of cation substituents from Group IA of the Periodic Table, cation substituents from Group IIA of the Periodic Table, zinc cation substituents and combinations of these.

3. A process as recited in claim 2, in which the adsorbent has cation substituents selected from the group consisting of silver substituents in a valence state of one and sodium substituents and combinations of these.

4. A process as recited in claim 3, in which the adsorbent is characterized by a level of silver substituents greater than about 0.05 millimoles/100 square meters of adsorbent surface area.

5. A process as recited in claim 4, in which the solvent in each step has the same composition and is characterized by a solubility parameter (on a 25°C. basis) ranging from about 7.0 to about 10.5, a solubility parameter dispersion component (on a 25°C. basis) ranging from about 7.0 to about 9.0, a solubility parameter polar component (on a 25°C. basis) ranging from about 0.2 to about 5.1, and a solubility parameter hydrogen bonding component (on a 25°C. basis) ranging from about 0.3 to about 7.4.

6. A process as recited in claim 5, in which the solvent is characterized by a solubility parameter (on a 25°C. basis) ranging from about 7.4 to about 9.0, a solubility parameter dispersion component (on a 25°C. basis) ranging from about 7.25 to about 8.0, a solubility parameter polar component (on a 25°C. basis) ranging from about 0.5 to about 3.0 and a solubility parameter hydrogen bonding component (on a 25°C. basis) ranging from about 0.7 to about 4Ø

7. A process as recited in claim 5 in which said solvent comprises ethyl acetate.

8. A process as recited in claim 5, in which said adsorbent is derived from silica gel having a surface area of at least about 300 square meters per gram and is further characterized by a ratio of surface-silicon atoms to aluminum atoms ranging from about 3:1 to about 12:1, a silver level ranging from about 0.10 millimoles/100 square meters of adsorbent surface area to about 0.35 millimoles/
100 square meters of adsorbent surface area, and a moisture content less than about 4% by weight.

9. A process as recited in claim 8, which is carried out by a continuous simulated moving bed technique.

10. A process as recited in claim 9, in which the mixture of triglycerides being separated is refined and bleached sunflower oil and in which fraction obtained in step (d) contains less than about 3.5% by weight saturated fatty acid moiety (on a fatty methyl ester basis).

11. A process as recited in claim 10 in which the simulated moving bed technique involves use of a plurality of successive desorption zones.

12. A process as recited in claim 9, in which the mixture of triglycerides which is separated is refined, bleached and deodorized soybean oil containing from about 6.5% to about 8.5% by weight linolenic acid moiety (on a fatty methyl ester basis) and having an Iodine Value ranging from about 130 to about 150 and in which the fraction ob-tained in step (b) contains from 0% to about 5% by weight linolenic acid moiety (on a fatty methyl ester basis) and has an Iodine Value ranging from about 80 to about 125.

13. A process as recited in claim 4, in which the solvent in step (a), the adsorption vehicle, has a different composition from the solvent in step (c), the desorbent.

14. A process as recited in claim 13, in which the adsorption vehicle is characterized by a solubility parameter (on a 25°C. basis) ranging from about 7.3 to about 14.9, a solubility parameter dispersion component (on a 25°C. basis) ranging from about 7.3 to about 9.0, a solubility parameter polar component (on a 25°C. basis) ranging from 0 to about 5.7, and a solubility parameter hydrogen bonding component (on a 25°C. basis) ranging from 0 to about ll.0; in which the desorbent is characterized by a solubility parameter (on a 25°C. basis) ranging from about 7.4 to about 15.0 and at least 0.1 greater than that of the adsorption vehicle, a solubility parameter dispersion component (on a 25°C. basis) ranging from about 7.3 to about 9.0, a solubility parameter polar component (on a 25°C. basis) ranging from about 0.3 to about 6.0 and at least 0.3 greater than that of the adsorption vehicle, and a solubility parameter hydrogen bonding component (on a 25°C. basis) ranging from about 0.5 to about 11.5 and at least 0.5 greater than that of the adsorption vehicle.

15. A process as recited in claim 14, in which the adsorption vehicle is characterized by a solubility parameter (on a 25°C. basis) ranging from about 7.3 to about 9.0, a solubility parameter dispersion component (on a 25°C. basis) ranging from about 7.3 to about 8.0, a solubility parameter polar component (on a 25°C. basis) ranging from 0 to about 2.7, and a solubility parameter hydrogen bonding component (on a 25°C. basis) ranging from 0 to about 3.6 and in which the desorbent is characterized by a solubility parameter (on a 25°C. basis) ranging from about 7.4 to about 10.0, a solubility parameter dispersion component (on a 25°C. basis) ranging from about 7.3 to about 8.0, a solubility parameter polar component (on a 25°C. basis) ranging from about 0.5 to about 4.0 and a solubility parameter hydrogen bonding component (on a 25°C. basis) ranging from about 0.5 to about 6Ø

16. A process as recited in claim 15, in which the adsorption vehicle comprises hexane and in which the desor-bent comprises ethyl acetate.

17. A process as recited in claim 14, in which said adsorbent is derived from silica gel having a surface area of at least about 300 square meters per gram and is further characterized by a ratio of surface-silicon atoms to alum-inum atoms ranging from about 3:1 to about 12:1, a silver level ranging from about 0.10 millimoles/100 square meters of adsorbent surface area to about 0.35 millimoles/100 square meters of adsorbent surface area, and a moisture content less than about 4% by weight.