JP2018517037A - Method for removing metal contaminants from glyceride oil and method for purifying glyceride oil incorporating the same - Google Patents

Abstract

The present invention is directed to a method for removing metal contaminants from glyceride oil and a purification method incorporating the same. In particular, the present invention is directed to a method of treating glyceride oil using certain basic ionic liquids. The invention also relates to the use of basic ionic liquids and glyceride oil compositions resulting from ionic liquid processing.

Description

  The present invention is directed to a method for removing metal contaminants from glyceride oil and a purification method incorporating the same. In particular, the present invention is directed to a method of treating glyceride oil using certain basic ionic liquids. The invention also relates to the use of basic ionic liquids and glyceride oil compositions resulting from ionic liquid processing.

  Crude glyceride oils extracted from natural sources are typically subjected to a variety of purification steps to improve the sensory stimulating properties or other quality parameters of the oil, depending on the intended use. Typically, methods of refining oil extract lipids, pigments, volatile aroma compounds, and other components that adversely affect oil stability or present potential toxicity issues. Glyceride oil is known to be used in biodiesel production, as well as human consumption and healthcare products. One problem that affects these applications is the metal content of the crude glyceride oil.

  The main metal contaminant of crude glyceride oil is iron, which is believed to be derived from the machinery and tanks used during processing and storage. Iron, zinc, and copper are known to be pro-oxidant metals that catalyze the oxidation process and can contribute to the oxidative degradation of glyceride oils. It is also known that crude glyceride oils contain substantial amounts of sodium, potassium, calcium, magnesium, chromium, nickel, and aluminum metals. Potassium, calcium, and magnesium are known to be the most abundant metal components in plant materials, and thus these metals can be endogenously introduced into vegetable oils extracted from plant materials.

  The presence of metals in glyceride oils can have a detrimental effect on oil stability, which can have a significant impact on the organoleptic properties of consumer use oils. Metal contaminants, especially iron, can darken the oil during deodorization, and even a small amount of iron significantly reduces the stability of the oil. It is also well known that glyceride oils can also be used for biodiesel production using transesterification, which converts the triglyceride component of the oil to fatty acid methyl ester (FAME) by contacting with alcohol in the presence of a catalyst. ing. Oil metal contaminants can have a detrimental effect on the performance of transesterification catalysts, and in biodiesel production processes it is preferred that the oil has a low metal content to mitigate catalyst deactivation. . Therefore, there is a need to remove glyceride oil metal contaminants in both food and biodiesel applications.

  Purification of glyceride oil typically includes degumming, including washing with water and / or treating with an aqueous acid (phosphoric acid and / or citric acid). The water-washing step removes the hydratable phosphatide and the acid treatment step removes the non-hydratable phospholipid component. The degaming step removes the phosphorus source as a result of removing the phospholipid component. The degaming step is also known to simultaneously remove from the oil the metal ions that form salts of phosphatidic acid in non-hydratable phosphatides. Purification also typically includes a bleaching step (eg, using bleaching earth) that not only improves color, but is also used to remove contaminants including trace metals. However, the degumming and bleaching steps may not necessarily be sufficient to remove metal contaminants, particularly iron, to an extent appropriate for biodiesel applications in particular.

  US Pat. No. 4,629,588 discloses a method for purifying glyceride oils using amorphous silica to remove phospholipids and related metal ions from glyceride oils. This method relies on the presence of phospholipids for the removal of metal ions and effectively corresponds to the degaming method.

  U.S. Pat. No. 3,634,475 discloses a method for removing metals from vegetable oils comprising the step of countercurrent multi-stage washing with water of a vegetable oil that has been previously treated to remove cations by contacting with a cation exchange resin. Has been.

  In WO 2003/075671, polar materials, free fatty acids, metals, colorants, and soaps are treated by treating oil with a composition comprising an effective amount of silica, acidic alumina, clay, and optionally citric acid. A method for removing contaminants including is disclosed.

  U.S. Pat. No. 8,764,967 discloses a method for regenerating spent cooking oil using an electrochemical device comprising a proton exchange membrane disposed between an anode and a cathode, produced as a result of water hydrolysis. A method is disclosed in which the generated hydrogen gas reacts with the metal ions contained in the oil to facilitate the removal of the metal ions.

  In US Pat. No. 6,407,271, the oil is emulsified with an aqueous solution of a polycarboxylic acid salt, preferably tetrasodium EDTA, to produce a fine suspension of micelles, followed by centrifugation or ultrafiltration. A method for removing phospholipids and / or polyvalent metals from vegetable oils is disclosed. EDTA salts chelate with polyvalent metal cations (eg, Fe (II), Fe (III), Ca (II), and Mg (II)), and metal cations used in the degaming step, and phosphatidic acid Or more stable complexes than phosphoric acid or citric acid salts.

  International Publication No. 1994/021765 describes a method of neutralizing FFA in glyceride oil and simultaneously removing contaminants including trace metals. Prior to heating and filtration, the oil is contacted with a solid alkali metal silicate, such as sodium metasilicate pentahydrate, and hydrous sodium polysilicate.

  International Publication No. 2012/004810 discloses a method of removing fat and oil metals by treating with clay and then treating with an ion exchange resin. This method depends on both the adsorbent and the resin material, and in particular if the step of regenerating to recycle the clay and / or ion exchange resin is incorporated into the method, the material costs and equipment associated with the method of purification. Increase both the cost.

  Liquid-liquid extraction techniques using polar solvents have been traditionally disclosed as oil treatments, such as FFA removal, for example, oil separation due to differential solubility of contaminants and selective partitioning to specific solvent phases. effecting separation). Meirelles et al., Recent Patents on Engineering 2007, 1, 95-102 provides an overview of such techniques for deoxidizing vegetable oils. Liquid-liquid extraction methods are generally considered advantageous on the basis that they can be performed at room temperature, do not produce waste, and benefit from low neutral oil loss. However, Meirelles et al. Believe that there is considerable capital cost associated with the implementation of the liquid-liquid extraction method and there is still suspicion for the overall benefit. Furthermore, the polar solvents used in this liquid-liquid extraction technique often can remove monoglycerides and diglycerides from oils in addition to FFA, which may be undesirable.

  J. Chem. Tecnol. Biotechnol. 80: 1089-1096 (2005) reviews the recent use of ionic liquids as solvents in the extraction of a variety of substances, including metal ions. However, these extractions relate only to extraction from aqueous systems. There is no example where metal ions are extracted from the oil phase to the immiscible ionic liquid phase.

  Refining alternative glyceride oils, including metal removal steps, that can provide high-value refined glyceride oil products while maximizing energy savings and minimizing material costs related to the overall refining process It would be beneficial if there was a way to do it.

  The present invention is based on the use of a basic ionic liquid containing a basic anion, specifically selected for extracting metals from glyceride oils, whose treatment can be easily incorporated into the overall method of purifying glyceride oils. it can. Treatment of glyceride oil with a basic ionic liquid typically removes pigments and fragrance compounds that are removed in the separation and bleaching and high temperature deodorizing steps (eg, 240 ° C. to 270 ° C.), respectively, of conventional purification methods. It was revealed that it was at least partially removed. It has also been found that treatment with basic ionic liquids at least partially degams glyceride oil. Thus, the treatment of glyceride oil with a basic ionic liquid can use a lower temperature and / or shorter time interval for the deodorizing step that is part of the overall purification process, even if done at a narrower range. Means that degumming and / or bleaching of This has the advantage of relaxing the energy requirements associated with the purification method and lowering material costs.

US Pat. No. 4,629,588 US Pat. No. 3,634,475 International Publication No. 2003/077561 Pamphlet U.S. Pat. No. 8,764,967 US Pat. No. 6,407,271 International Publication No. 1994/021765 Pamphlet International Publication No. 2012/004810 Pamphlet

Meirelles et al., Recent Patents on Engineering 2007, 1, 95-102 J. Chem. Tecnol. Biotechnol. 80: 1089-1096 (2005)

Accordingly, in one aspect, the present invention is a method for removing metal from a metal-containing glyceride oil comprising:
(I) A step of bringing a metal-containing glyceride oil containing a metal having a total metal concentration of 10 ppm to 10,000 ppm into contact with a basic ionic liquid to produce a treated glyceride oil, wherein the basic ionic liquid is a hydroxide ion or an alkoxide. Select from ions, alkyl carbonate ions, bicarbonate ions, carbonate ions, serinate ions, prolineate ions, histinate ions, threoninate ions, valinate ions, aspartate ions, taurinate ions, and ricinate ions. Said generating step comprising a basic anion, as well as an organic quaternary ammonium cation;
(Ii) after bringing the glyceride oil into contact with the basic ionic liquid, separating the treated glyceride oil from the ionic compound containing an organic quaternary ammonium cation, wherein the treated glyceride oil is generated as described above ( said separating step having a reduced metal concentration compared to the glyceride oil contacted in i),
However, the method is provided wherein the contacted glyceride oil does not contain palm oil.

  In some embodiments of this aspect, the total concentration of metals in the glyceride oil prior to contacting in the generating step (i) is from 50 ppm to 5000 ppm, such as from 100 ppm to 2000 ppm.

  The basic ionic liquid treatment according to the method of the present invention can be suitably applied to a metal-containing crude glyceride oil that has not undergone any prior purification steps. Alternatively, the method can be applied to a metal-containing glyceride oil that has undergone one or more additional purification steps prior to treatment with a basic ionic liquid.

  Thus, treatment with a basic ionic liquid can be incorporated in several stages in a process for purifying glyceride oil. For example, the treatment may cause metal contaminants, particularly if not removed, to darken glyceride oil and adversely affect sensory irritation properties before exposure to high temperatures to reduce the amount of iron. Can be implemented in stages. Alternatively, the treatment is at the end of the refining process as a means to reduce the concentration of metal contaminants after contact with a metal container or metal machine associated with processing, particularly where metal leaching to oil is more likely at high temperatures. Can be implemented. This adaptability makes the treatment with basic ionic liquids according to the present invention particularly attractive for incorporation into existing purification methods and systems.

Thus, in another aspect, the invention also provides a method for refining a metal-containing glyceride oil, the method comprising:
(I) a step of bringing a metal-containing glyceride oil into contact with a basic ionic liquid to produce a treated glyceride oil, wherein the basic ionic liquid is a hydroxide ion, an alkoxide ion, an alkyl carbonate ion, a bicarbonate ion, A basic anion selected from carbonate ion, serinate ion, prolinate ion, histinate ion, threoninate ion, valinate ion, aspartate ion, taurinate ion, and ricinate ion; Said producing step comprising a quaternary ammonium cation;
(Ii) after bringing the glyceride oil into contact with the basic ionic liquid, separating the treated glyceride oil from the ionic compound containing an organic quaternary ammonium cation, wherein the treated glyceride oil is generated as described above ( said separating step having a reduced metal concentration compared to the glyceride oil contacted in i);
(Iii) subjecting the treated glyceride oil after said separating step (ii) to at least one further purification step,
However, the method is also provided wherein the contacted glyceride oil does not contain palm oil.

  In some embodiments of this aspect, the total concentration of metals in the glyceride oil prior to contacting in the generating step (i) is 10 ppm to 10000 ppm, preferably 50 ppm to 5000 ppm, most preferably 100 ppm to 2000 ppm. .

  As used herein, the term “glyceride oil” refers to an oil or fat that contains triglycerides as its major component. For example, the triglyceride component can be at least 50% by weight of the glyceride oil. The glyceride oil may also contain monoglycerides and / or diglycerides. Preferably, the glyceride oil is obtained at least in part from a natural source (eg, a plant, animal or fish / crustacean source) and is preferably also edible. Glyceride oils include vegetable oils, marine oils, and animal oils / fats that typically also contain a phospholipid component in their crude state.

  Vegetable oils include all plant, nut and seed oils. Examples of suitable vegetable oils that may be used in the present invention include acai oil, almond oil, beech oil, cashew oil, coconut oil, colza oil, corn oil, cottonseed oil, grapefruit seed oil, grape seed oil, Hazelnut oil, cannabis oil, lemon oil, macadamia oil, mustard oil, olive oil, orange oil, peanut oil, pecan oil, pine nut oil, pistachio oil, poppy oil, rapeseed oil, rice bran oil, safflower oil , Sesame oil, soybean oil, sunflower oil, walnut oil, and wheat germ oil. Preferred vegetable oils are oils selected from coconut oil, corn oil, cottonseed oil, groundnut oil, olive oil, rapeseed oil, rice bran oil, safflower oil, soybean oil, and sunflower oil.

  Suitable aquatic oils include oils derived from oily fish or crustacean (eg creel) tissue. Examples of suitable animal oils / fats include lard, duck fat, goose fat, tallow oil, and butter.

  FFAs that may be present in glyceride oils include monounsaturated FFAs, polyunsaturated FFAs, and saturated FFAs. Examples of unsaturated FFAs include myristoleic acid, palmitoleic acid, sapienoic acid, oleic acid, elaidic acid, vaccenic acid, linoleic acid, linoelaidic acid, α-linolenic acid, arachidonic acid, eicosapentaenoic acid, erucic acid, and An example is docosahexaenoic acid. Examples of saturated FFAs include caprylic acid, capric acid, undecyl acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, margaric acid, stearic acid, nonadecylic acid, arachidic acid, heicosylic acid, behenic acid, Examples include lignoceric acid and serotic acid.

  Preferably, the glyceride oil used in the present invention is a vegetable oil. More preferably, the glyceride oil is a vegetable oil selected from coconut oil, corn oil, cottonseed oil, peanut oil, olive oil, rapeseed oil, rice bran oil, safflower oil, soybean oil, and sunflower oil.

  The term “soybean oil” as used herein includes oil extracted from soybean (Glycine max) seeds. The term “rapeseed oil” as used herein is synonymous with canola oil, for example, rapeseed (Brassica napus L.) or rape / rape (Brassica rapa subsp. Oleifera). , Refers to oil derived from rapeseed species of Chinese cabbage (syn. B. campestris L.).

  The method for purifying glyceride oils according to the present invention does not extend to glyceride oils including palm oil. As used herein, the term “palm oil” forms part of the Arecaceae genera, and is a species of Guinea oil palm (Elaeis guineensis) (African oil palm) and American oil palm (Elaeis oleifera) species (American oil palm). Or oil derived at least partially from the genus Elaeis tree, including its hybrids. Thus, references herein to palm oil also include palm kernel oil and fractionated palm oil, such as palm oil stearin fraction or palm oil olein fraction.

  The term “crude” as used herein with respect to glyceride oil is intended to mean a glyceride oil that has not undergone a purification step following oil extraction. For example, the crude glyceride oil will not have undergone a degaming step, a deoxidizing step, a dewaxing step, a bleaching step, a decolorizing step, or a deodorizing step. “Purified” as used herein with respect to glyceride oil is 1 or 2 such as degaming, deoxidizing, dewaxing, bleaching, decolorizing, and / or deodorizing. It is intended to mean a glyceride oil that has undergone the above refining steps.

  The term “metal” as used herein with respect to metal-containing glyceride oils is intended to refer to metal-containing compounds or metal-containing complexes and free metal ions. Metal-containing compounds include metal salts, metal oxides, metal sulfides, and the like, while metal complexes include, for example, coordination complexes. Examples of metals that can be removed as part of the basic ionic liquid treatment of the present invention include alkali metals (eg, lithium, sodium, and potassium), alkaline earth metals (eg, beryllium, magnesium, calcium, strontium). , And barium), transition metals (eg, chromium, manganese, iron, cobalt, nickel, copper, zinc, cadmium, and mercury), and post transition metals (eg, aluminum, tin, and lead). A preferred class of metals for removal from glyceride oils are transition metals.

  Specific examples of metals preferred for removal by the basic ionic liquid treatment according to the present invention include sodium, potassium, calcium, magnesium, strontium, barium, iron, zinc, nickel, copper, chromium, and aluminum. Particularly preferred metals for removal from the oil include strontium, barium, iron, copper, nickel, and chromium. The most preferred metals for removal from the oil are iron and copper.

  The term “ionic liquid” as used herein is a liquid that can be produced by dissolving a salt, in which case it is a liquid consisting only of ions. The ionic liquid may be generated from a uniform material containing one type of cation and one type of anion, or may be composed of two or more types of cation and / or two or more types of anion. Therefore, the ionic liquid may be composed of two or more types of cations and one type of anions. The ionic liquid may be further composed of one kind of cation and one or more kinds of anions. Furthermore, the ionic liquid may be composed of two or more types of cations and two or more types of anions.

  The term “ionic liquid” includes both compounds having a high melting point and compounds having a low melting point, eg, below room temperature. Thus, many ionic liquids have a melting point below 200 ° C, preferably below 150 ° C, especially below 100 ° C, near room temperature (15-30 ° C), or even below 0 ° C. An ionic liquid having a melting point below about 30 ° C. is commonly referred to as a “room temperature ionic liquid”. In room temperature ionic liquids, the structure of the cation and anion prevents the formation of a regular crystal structure, so that the salt is liquid at room temperature.

  As used herein, the term “ionic liquid” also includes “unorthodox” ionic liquids that exhibit ionic liquid properties, but exist stably in the presence of a solvent or only on a support. For example, the basic ionic liquid used according to the present invention also includes a quaternary ammonium hydroxide ionic liquid. These ionic liquids are typically considered as “unorthodox” ionic liquids because they can be unstable by Hoffman desorption in a neat form. Nevertheless, such ionic liquids are known to exist stably when immobilized on a support (see, for example, Chem. Commun., 2004, 1096-1097) or in the presence of a solvent, such as an aqueous co-solvent. It has been. The basic ionic liquid used in accordance with the present invention also includes a quaternary ammonium bicarbonate ionic liquid. These ionic liquids are still typical because they can suffer from Hoffman desorption (to a much lesser extent than hydroxide-based ionic liquids) and thermal decomposition of the bicarbonate anion to the carbonate form. Is considered to be a “unorthodox” ionic liquid. Nevertheless, such ionic liquids are known to exist stably in the presence of a solvent, such as an aqueous solvent.

  Thus, when “unorthodox” basic ionic liquids are used in accordance with the present invention, a liquid comprising a basic ionic liquid can be used along with a solvent such as an aqueous solvent. Additional co-solvents such as alcohol co-solvents may also be included. Preferred embodiments in which the ionic liquid is used in combination with a solvent are described in more detail below.

  Ionic liquids are most widely known as solvents that also make them environmentally friendly due to their negligible vapor pressure, temperature stability, low flammability, and reusability. Due to the vast number of available anion / cation combinations, the physical properties of the ionic liquid (eg, melting point, density, viscosity, and miscibility with water or organic solvents) to meet the requirements of a particular application It is possible to make fine adjustments.

  Thus, ionic liquids have heretofore been developed as solvents for the synthesis of various organic compounds and polymers because of their advantageous properties. There have been many reports contemplating the various roles that ionic liquids will play when used as solvents. In S.-I.Ishiguro et al., Pure Appl. Chem., Vol. 82, No. 10, pp 1927 to 1941, 2010, solute-solvent interaction in a reaction in which an ionic liquid is considered to act as a solvent, Alternatively, the important role played by solvation of solute ions or solute molecules has been reported. The important role that the liquid structure of these solvents plays in the reaction is particularly emphasized in solutions where the solvent particles can move into the bulk liquid structure and be liberated in the reaction before being contained.

  According to S.-I. Ishiguro et al., The liquid structure of an ionic liquid is heterogeneous, unlike a molecular solvent, and thus can provide the unique solvent properties and specific solute reactivity of an ionic liquid. However, it has been observed that the acid-base properties of ionic liquids have not been satisfactorily established with respect to solution chemistry, for example, especially compared to conventional molecular liquids. Therefore, it is difficult to predict the role that ionic liquids may play in certain solution-based reactions.

  In this specification, when referring to “an ionic compound containing an organic quaternary ammonium cation” in step (ii), at least by the organic quaternary ammonium cation contained in the ionic compound separated in step (ii) , Intended to refer to an ionic compound derived from the basic ionic liquid contacted in step (i). In some embodiments, the glyceride oil comprises FFA and the ionic compound comprising an organic quaternary ammonium cation also comprises an anion of a fatty acid. The ionic compound separated from the treated glyceride oil may be an ionic liquid as defined herein, but is different from the basic ionic liquid used to initially contact the glyceride oil. In a further embodiment, the ionic compound comprising an organic quaternary ammonium cation comprises the same anion as the ionic liquid used to initially contact the glyceride oil. In other words, the ionic compound separated from the treated glyceride oil is the same as the ionic liquid originally used to contact the glyceride oil.

The ionic liquid used in the process of the present invention is based on an organic quaternary ammonium cation. “Organic quaternary ammonium cation” as used herein is intended to refer to a positively charged ammonium cation in which the nitrogen atom is bonded only to a substituted or unsubstituted C ₁ -C ₁₂ hydrocarbyl group. The term “hydrocarbyl group” refers to a monovalent or polyvalent radical derived from a hydrocarbon and can include alkyl, cycloalkyl, alkenyl, alkynyl, or aryl groups.

Preferably, the organic quaternary ammonium cation of the basic ionic liquid is
[N (R ^a ) (R ^b ) (R ^c ) (R ^d )] ⁺
Wherein R ^a , R ^b , R ^c , and R ^d are each independently selected from a linear or branched C ₁ -C ₈ alkyl group, or a C ₃ -C ₆ cycloalkyl group. Or any two of R ^a , R ^b , R ^c , and R ^d combine to form an alkylene chain — (CH ₂ ) _q —, where q is 3-6, and the above alkyl group Or a cycloalkyl group is C ₁ -C ₄ alkoxy, C ₂ -C ₈ alkoxy alkoxy, C ₃ -C ₆ cycloalkyl, —OH, —SH, —CO ₂ (C ₁ -C ₆ ) alkyl, and —OC. (O) It may be substituted with 1 to 3 groups selected from (C ₁ -C ₆ ) alkyl, for example, with 1 to 3 —OH groups.
Selected from.

More preferably, the organic quaternary ammonium cation of the basic ionic liquid is
[N (R ^a ) (R ^b ) (R ^c ) (R ^d )] ⁺
Wherein R ^a , R ^b , R ^c and R ^d are each independently selected from a linear or branched C ₁ -C ₈ alkyl group, wherein the alkyl group is C ₁ -C _{4 alkoxy,} C 2 -C _{8 alkoxyalkoxy,} C 3 -C _{6 cycloalkyl, -OH, -SH, -CO 2 (} C 1 -C 6) alkyl, and _{-OC (O) (C 1 -C} 6) (It may be substituted with 1 to 3 groups selected from alkyl, for example, with 1 to 3 —OH groups.)
Selected from.

Even more preferably, the organic quaternary ammonium cation is
[N (R ^a ) (R ^b ) (R ^c ) (R ^d )] ^{+
(Wherein, R a, R b, R} c, and ^{R d} are each _{independently,} C 1, _{C 2,} and alkyl of _{C 4,} linear or branched _C 1 -C ₄ alkyl And at least one of R ^a , R ^b , R ^c , or R ^d is substituted by one —OH group.
Selected from.

  Most preferably, the organic quaternary ammonium cation is choline.

  The basic ionic liquid used in the present invention includes hydroxide ion, alkoxide ion, alkyl carbonate ion, hydrogen carbonate ion, carbonate ion, serinate ion, prolineate ion, histinate ion, threoninate ion, and valinate. Incorporates a basic anion selected from ions, aspartate ions, taurinate ions, and ricinate ions. These anions are not only bystander anions selected by their ability to impart a certain melting point to the resulting ionic liquid. It is believed that the basicity of the anions forming part of the ionic liquid used in connection with the present invention contributes to the ability of the ionic liquid to remove chloropropanol and glycidol, or fatty acid esters thereof, from glyceride oil. The term “basic” as used herein refers to a Bronsted base that has the ability to react with an acid (to neutralize the acid) to form a salt. The pH range of the base is higher than 7.0 and lower than 14.0 when dissolved or suspended in water.

  In one embodiment of the invention, the basic anion is selected from alkyl carbonate ions, bicarbonate ions, carbonate ions, hydroxide ions, and alkoxide ions, preferably from bicarbonate ions, alkyl carbonate ions, and carbonate ions. Selected, and more preferably hydrogen carbonate ions.

  When the basic anion is selected from an alkoxide ion or an alkyl carbonate ion, the alkyl group may be linear or branched, and may be substituted or unsubstituted. In one preferred embodiment, the alkyl group is unsubstituted. In other preferred embodiments, the alkyl group is unbranched. In a more preferred embodiment, the alkyl group is unsubstituted and unbranched.

  The alkyl group can contain 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms. Thus, the alkyl group can be selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and / or decyl. It will be understood that branched alkyl groups such as iso-propyl, iso-butyl, sec-butyl, and / or tert-butyl can also be used. Particularly preferred are methyl, ethyl, propyl and butyl. In a further preferred embodiment, the alkyl group is selected from methyl and ethyl.

  In an embodiment of the present invention, the basic anion is selected from serinate ion, prolinate ion, histinate ion, threoninate ion, valinate ion, aspartate ion, taurinate ion, and ricinate ion. The

  In a preferred embodiment of the present invention, the basic anion is selected from serinate ion, lysinate ion, prolineate ion, taurinate ion, and threoninate ion, more preferably lysinate ion, prolineate ion, and Selected from serinate ions, most preferably the basic anion is a ricinate ion.

  In order to adapt the glyceride oil obtained directly from the process of the present invention for consumption, to contact the glyceride oil of step (i) and the ionic compound comprising the organic quaternary ammonium cation separated in step (ii) It should be recognized that the basic ionic liquid used has little or no toxicity and / or can be easily and sufficiently separated from the oil to be treated. Basic ionic liquids containing choline cations are particularly suitable for use in the method of the present invention. Choline is a water-soluble basic nutrient classified into the vitamin B group, and is a precursor of acetylcholine involved in many physiological functions. Choline is a natural ingredient that has particularly low toxicity, has excellent biodegradability, and can produce ionic liquids that are particularly useful in the process of the present invention.

  Thus, in a particularly preferred embodiment of the invention, the basic ionic liquid is choline bicarbonate,

Or choline alkyl carbonate,

(Wherein the alkyl group is the alkyl group described above)
Or choline hydroxide

Selected from.

  A basic ionic liquid comprising a basic anion selected from serinate ion, prolinate ion, histinate ion, threoninate ion, valinate ion, aspartate ion, taurinate ion, and ricinate ion is also These amino acid derivatives are particularly suitable for the method of the present invention because of their particularly low toxicity.

  In the most preferred embodiment of the invention, the basic ionic liquid is choline bicarbonate.

  The basic ionic liquid used in step (i) and the ionic compound comprising the organic quaternary ammonium cation separated in step (ii) preferably have low oil solubility and preferentially in the aqueous phase. To the non-oil phase to facilitate its removal from the oil to be treated. More preferably, the basic ionic liquid is immiscible with the oil. By being immiscible with oil, it is meant that the ionic liquid can be dissolved in glyceride oils at a concentration of less than 50 ppm, preferably less than 30 ppm, more preferably less than 20 ppm, most preferably less than 10 ppm, for example less than 5 ppm. Accordingly, the solubility of the basic ionic liquid can be adjusted so that the basic ionic liquid is immiscible with the oil.

  Suitably, the contacting step (i) of the method of the present invention comprises a temperature of less than 80 ° C, preferably a temperature of 25-65 ° C, more preferably a temperature of 35-55 ° C, for example a temperature of 40 ° C. Will be implemented. As will be appreciated, higher temperatures are preferred so that when the glyceride oil is semi-solid at room temperature, it is in liquid form for contact with a liquid comprising a basic ionic liquid. Preferably, the contacting step (i) is carried out at a pressure of 0.1 MPa absolute pressure to 10 MPa absolute pressure (1 bar absolute pressure to 100 bar absolute pressure).

  In some embodiments, the contacting step comprises stirring the resulting mixture, for example, using a mechanical stirrer, ultrasonic stirrer, electromagnetic stirrer, or by bubbling an inert gas in the mixture. Can be carried out by bringing the glyceride oil into contact with the basic ionic liquid in a container to be made.

  Suitably, the basic ionic liquid and the glyceride oil can be contacted in a volume ratio of greater than 1:40 and up to 1: 300, and contacted in a mass ratio from 1:50, preferably from 1: 100. be able to. The contacting step can last from 1 minute to 60 minutes, preferably 2 to 30 minutes, more preferably 5 to 20 minutes, and most preferably 8 to 15 minutes.

  In step (i), the basic ionic liquid is contacted with glyceride oil. The basic ionic liquid can be added in neat form or as part of a liquid that additionally contains a solvent or solvent mixture that is compatible with the basic ionic liquid and the glyceride oil. A solvent or solvent mixture may be used to improve the viscosity of the basic ionic liquid as desired. Alternatively, by using a solvent, it is possible to impart desired characteristics particularly suitable for promoting the reaction of the basic ionic liquid to the liquid structure of the liquid reaction. Suitable solvents for this use include polar solvents such as water or alcohols such as methanol or ethanol.

  In some embodiments, the glyceride oil is contacted with a liquid comprising a basic ionic liquid and a solvent, wherein the concentration of the basic ionic liquid in the liquid is 15% to 90% by weight. In an exemplary embodiment, the solvent is an aqueous solvent such as pure water.

  In a preferred embodiment, when the basic anion of the basic ionic liquid is selected from alkyl carbonate ions, bicarbonate ions, and carbonate ions, particularly when the basic anion is bicarbonate ions, the glyceride oil is The liquid is brought into contact with a liquid containing a solvent such as an ionic liquid and an aqueous solvent, and the concentration of the basic ionic liquid in the liquid is 50% by weight to 90% by weight, for example, 75% by weight to 85% by weight.

  In a preferred embodiment, when the basic anion of the basic ionic liquid is selected from hydroxide ions and alkoxide ions, particularly when the basic anion is hydroxide ion, the glyceride oil is added to the basic ionic liquid and The liquid is brought into contact with a liquid containing a solvent such as an aqueous solvent, and the concentration of the basic ionic liquid in the liquid is 15% by weight to 60% by weight, preferably 40% by weight to 50% by weight.

  In the above embodiment, if the basic ionic liquid is part of a mixture with a solvent, an additional co-solvent may also be included. For example, when an aqueous solvent is used, the alcohol co-solvent (s) may be included between 1% and 20% by weight of the liquid including, for example, the basic ionic liquid and the aqueous solvent.

  In the above embodiment, if the basic ionic liquid is part of a mixture with a solvent, an additional co-solvent may also be included. For example, when an aqueous solvent is used, the alcohol co-solvent (s) may also be included, for example, between 1% and 20% by weight of the liquid comprising the basic ionic liquid and the aqueous solvent.

  Separation of ionic compounds containing organic quaternary ammonium cations in step (ii) of the method can be carried out by gravity separation (eg in a sedimentation device), where the treated glyceride oil is generally An ionic compound which is an upper phase and contains an organic quaternary ammonium cation together with an arbitrary solvent is incorporated into the lower phase. The step of separating the ionic compound containing the organic quaternary ammonium cation can also be accomplished using, for example, a decanter, hydrocyclone, electrostatic combination, centrifuge, or membrane filter press. Preferably the phases are separated using a centrifuge. The contacting step and the separating step can be repeated a plurality of times, for example, 2 to 4 times.

  If the ionic compound containing the organic quaternary ammonium cation separated in step (ii) is a solid that settles after contacting step (i), for example following formation of a quaternary ammonium-FFA salt, The ionic compound can be separated from the oil by filtration. Alternatively, the polar solvent described above that is immiscible with the oil phase can be added to dissolve the solid salt, followed by separation of the salt-containing phase from the oil by the methods described above.

  Both the contacting and separating steps can be carried out in a countercurrent reaction column. Glyceride oil (hereinafter “oil feed stream”) is generally introduced at or near the bottom of the countercurrent reaction column, and basic ionic liquid (hereinafter “ionic liquid feed stream”) is introduced at the top of the countercurrent reaction column. Or introduced near the top. The oil phase to be treated (hereinafter “product oil stream”) is withdrawn from the top of the column and contains an ionic compound containing organic quaternary ammonium cations and, if present, a solvent (hereinafter “second stream”). , Drawn at or near the bottom of the column. Preferably, the countercurrent reaction column has a sump area that collects the second stream. Preferably, the oil feed stream is introduced into a countercurrent reaction column immediately above the sump area. Two or more countercurrent reaction columns can be used, for example, 2-6, preferably 2-3 columns arranged in series. Preferably, the countercurrent reaction column can be packed with a structured packing material, such as a glass Raschig ring, thereby increasing the oil and basic ionic liquid effluent paths through the column. Alternatively, the countercurrent reaction column may comprise a plurality of trays.

  In a particularly preferred embodiment, the contacting and separating steps are both centrifugal contact separators, such as US Pat. No. 4,959,158, US Pat. No. 5,571,070, US Pat. No. 5,591,340, US Pat. No. 5,762,800. No. 1, WO 99/12650, and WO 00/29120. Suitable centrifugal contact separators include those from Costner Industries Nevada, Inc. A liquid comprising glyceride oil and ionic liquid can be introduced into the annular mixing region of the centrifugal contact separator. Preferably, the glyceride oil and the basic ionic liquid are introduced into the annular mixing zone as a separate feed stream. The glyceride oil and the basic ionic liquid are rapidly mixed in the annular mixing zone. The resulting mixture is then clearly separated into an oil phase and a second phase through the separation region, with the application of centrifugal force.

  Preferably, a plurality of centrifugal contact separators, preferably 2-6, for example 2-3, are used in series. Preferably, the oil feed stream is introduced into the first centrifugal contact separator in series while the basic ionic liquid feed stream is introduced into the final centrifugal contact separator in series, for example FFA or free An oil with a progressively reduced content of metal cations passes from the first centrifugal contact separator in series to the final centrifugal contact separator while the content of, for example, quaternary ammonium-FFA salts and / or metal cations is increased. An increasing basic ionic liquid stream is passed from the final centrifugal contact separator in series to the first centrifugal contact separator. Thus, the phase containing the ionic compound containing the organic quaternary ammonium cation is removed from the first centrifugal contact separator and the treated oil phase is removed from the final centrifugal contact separator in series.

  If necessary, the residual basic ionic liquid contained in the glyceride to be treated can be recovered by passing the produced oil stream through a silica column and adsorbing the residual ionic liquid on the silica column. The adsorbed ionic liquid can then be washed off from the silica column using a solvent for the ionic liquid, and the ionic liquid can be recovered by blowing off the solvent under reduced pressure.

  The treated glyceride oil is used to coalesce fine droplets of non-oil phase liquids, such as ionic compounds containing organic quaternary ammonium cations, to produce a continuous phase and promote phase separation. It can also be passed through a coalescer filter. Preferably, when the basic ionic liquid used in the contacting step (i) is used in combination with a solvent, the coalescer filter is wetted with the same solvent to improve filtration.

  In some embodiments, a basic ionic liquid can be provided on the support. Suitable supports used in the present invention can be selected from silica, alumina, alumina-silica, carbon, activated carbon, or zeolite. Preferably, the support is silica. Depending on the supported form, it can be contacted with the oil as a slurry containing a suitable solvent. The solvent is as described above.

  If a supported basic ionic liquid is used, the contacting and separating steps are both by passing oil through a column packed with the supported ionic liquid (ie, packed bed arrangement). It can also be implemented. Additionally or alternatively, a fixed bed structure with multiple plates and / or trays can be used.

  Methods for supporting an ionic liquid on a support are well known in the art, such as, for example, US Patent Application Publication No. 2002/0169071, US Patent Application Publication No. 2002/0198100, and US Patent Application Publication No. 2008/0306319. ing. Typically, the ionic liquid can be physisorbed or chemisorbed on the support, preferably physisorbed. In the method of the present invention, the ionic liquid is a basic ionic liquid: support mass ratio of 10: 1 to 1:10, preferably a basic ionic liquid: support mass ratio of 1: 2 to 2: 1. Can be adsorbed on.

  It has been found that the metal content of glyceride oil can be reduced by treatment of the metal-containing glyceride oil with a basic ionic liquid according to the present invention. Several reaction mechanisms are considered possible as a result of contacting the oil with the ionic liquid and are described in further detail below.

  The metal content of glyceride oil can be absorbed, for example by plants, from metal containers and metal machinery used for extraction, processing and storage of glyceride oil, and from metal contaminants contained in ecosystems. It is believed that it is derived from fertilizer or contaminated soil that can enter the chain. In some embodiments, the metal of the metal-containing glyceride oil is included in the form of free metal ions and / or as one or more metal-containing compounds or metal-containing complexes.

  In some embodiments, the metal-containing glyceride oil contacted in step (i) comprises one or more metals selected from alkali metals, alkaline earth metals, transition metals, and post-transition metals, Preferably a transition metal is included. In some embodiments, the metal-containing glyceride oil contacted in step (i) is lithium, sodium, potassium, beryllium, magnesium, calcium, chromium, manganese, iron, cobalt, nickel, copper, zinc, cadmium, mercury One or more metals selected from aluminum, tin, and lead.

  In a preferred embodiment, the metal-containing glyceride oil contacted in step (i) is one or more metals selected from sodium, potassium, calcium, magnesium, iron, zinc, nickel, copper, chromium, and aluminum. including. In a more preferred embodiment, the metal-containing glyceride oil contacted in step (i) comprises one or more metals selected from iron, copper, chromium and nickel. Most preferably, the glyceride oil contacted in step (i) comprises iron and / or copper.

  Without being bound by any particular theory, one possible reaction mechanism believed to extract metals by the basic ionic liquid treatment of the present invention is by formation of metal-containing complexes. Such complexes can include ionic complexes, complexes resulting from hydrogen bonding, and charge transfer complexes. Another possible means by which metals can be extracted by basic ionic liquid treatment is to produce salts that preferentially partition out of the oil phase by cation exchange with free metal cations. The basicity of the basic ionic liquid used according to the present invention can also improve the proton activity of the oil and can lead to precipitation of metal-containing compounds.

  It has been found that the basic ionic liquid used according to the present invention neutralizes the FFA contained in the oil and produces a quaternary ammonium-FFA salt. This salt produced as a result of the acid-base reaction can also complex with the metal and contribute to the removal of the metal from the oil when the salt is separated from the treated oil in step (ii). Thus, in some embodiments, when the glyceride oil contacted in step (i) comprises FFA, the ionic compound comprising an organic quaternary ammonium cation separated in step (ii) comprises an anion of a fatty acid. be able to.

As previously described, in some embodiments, the organic quaternary ammonium cation of a basic ionic _liquid, C 1 -C _{4 alkoxy,} C 2 -C _{8 alkoxyalkoxy,} C 3 -C ₆ cycloalkyl, - 1 or 2 of a hydrocarbyl group substituted by 1 to 3 groups selected from OH, —SH, —CO ₂ (C ₁ -C ₆ ) alkyl, —OC (O) (C ₁ -C ₆ ) alkyl The above can be included. When polar substituents are included, particularly —OH capable of forming hydrogen bonds, such groups can facilitate complex formation with metals in the oil. Thus, in a particularly preferred embodiment of the invention, the organic quaternary ammonium cation comprises at least one hydrocarbyl group substituted by one —OH.

  Analytical methods suitable for measuring the concentration of metals in glyceride oil include high resolution inductively coupled plasma (ICP) spectroscopy, such as ICP-MS (eg, J. Agric. Food Chem. 2013 Mar 6; 61 ( 9): 2276-83), or emission spectroscopy (ICP-OES), plasma emission spectroscopy (AJ Dijkstra and D. Meert, JAOCS 59, 199 (1982)), and X-ray fluorescence analysis. Preferably, ICP-OES analysis is used to determine the metal concentration associated with the present invention.

  In a preferred embodiment, the treated glyceride oil separated in step (ii) is at least more than the metal-containing glyceride oil contacted in step (i) as measured using, for example, ICP-OES analysis. It has a metal concentration of 50% by weight, preferably at least 75% by weight lower.

  When the treatment with the basic ionic liquid forms part of the method for purifying the metal-containing glyceride oil according to one aspect of the present invention, at least one further purification step is performed after the glyceride oil is treated with the basic ionic liquid. Is called. Engineers in the field include, for example, "Practical Guide to Vegetable Oil Processing", 2008, Monoj K. Gupta, AOCS Press, and the Edible Oil Processing section of the "AOCS Lipid Library" website (lipidlibrary.aocs.org) Various refining steps are known that are typically used in edible oil processing, including the refining steps described in.

  The at least one further purification step (iii) can be selected from, for example, a degaming step, a bleaching step, a dewaxing step, a decolorizing step, and a deodorizing step. Metal contaminants, particularly iron, can darken the glyceride oil during thermal exposure, such as in the deodorizing step, so that the basic ionic liquid treatment is preferably performed prior to the deodorizing step. Thus, in a preferred embodiment, the at least one further purification step according to the method of the invention comprises a deodorizing step.

  In some embodiments, the at least one further purification step (iii) comprises a degaming step, a bleaching step, and a deodorizing step. Alternatively, in other embodiments, the at least one further purification step (iii) comprises a deodorizing step and the method does not comprise a degaming step and / or a bleaching step. Thus, in an exemplary embodiment, the at least one further purification step includes a degaming step and a deodorizing step, but does not include a bleaching step. In other exemplary embodiments, the at least one further purification step includes a bleaching step and a deodorizing step, but does not include a degaming step.

  An additional advantage of treatment with a basic ionic liquid according to the present invention is that the treatment typically removes pigments and fragrances that are removed at high temperature deodorization steps (eg, 240 ° C. to 270 ° C.) during conventional purification processes. It has been found that the compound is at least partially removed. Treatment of glyceride oil with a basic ionic liquid means that lower temperatures and / or shorter time sections can be used for the deodorizing step which is part of the overall purification process. This has the advantage of relaxing the energy requirements of the purification method.

  The degaming step typically involves contacting the oil with aqueous phosphoric acid and / or aqueous citric acid to remove both hydratable and non-hydratable phosphatides (NHP). Typically, citric acid or phosphoric acid is added as a 50 wt% aqueous solution. Suitably the aqueous acid is used in an acid amount of from about 0.02% to about 0.20% by weight of the oil, preferably from 0.05% to about 0.10% by weight of the oil. It is done. Suitably, the degaming step is performed at a temperature of about 50-110 ° C, preferably 80-100 ° C, for example 90 ° C. The degaming step can suitably last from 5 minutes to 60 minutes, preferably from 15 to 45 minutes, more preferably from 20 to 40 minutes, for example 30 minutes. Following the acid treatment followed by sinking of the mucus, the aqueous phase is separated before the degummed oil is generally dried. The step of drying the degummed oil is preferably carried out at a temperature of 80-110 ° C. and in a suitable time segment, for example 20-40 minutes, under reduced pressure, for example 2-3 kPa (20-30 mbar).

  As known to those skilled in the art, for glyceride oils with a low phosphatide content (eg, less than 20 ppm by weight phosphorus) without significant dilution of phosphoric acid or citric acid with water (eg, 85% acid Solution) The added dry degaming method can be used. The NHP is converted to phosphatidic acid and a calcium or magnesium biphosphate salt that can be removed from the oil in the next bleaching step. It is known that dry degumming is not very suitable when the oil is rich in phosphatides, especially NHP, because an excessive amount of bleaching earth is required.

  The bleaching step is incorporated into the method of refining the edible oil and reduces color bodies, trace metals, and oxidation products, including chlorophyll, residual soap, and gum. The step of bleaching typically comprises contacting the oil with, for example, bleaching clay or bleaching earth in an amount of 0.5-5% by weight of clay, based on the mass of oil. The bleaching clay or bleaching clay is typically composed of one or more of three clay minerals, calcium montmorillonite, attapulgite, and merolith. Any suitable bleaching clay or bleaching earth can be used according to the present invention, including neutral activated clay and acid activated clay (eg bentonite). Suitably, the oil is contacted with the bleached clay for 15 to 45 minutes, preferably 20 to 40 minutes, before the soil is typically separated by filtration. Typically, the oil is contacted with bleaching clay or bleaching soil at a temperature of 80 ° C to 125 ° C, preferably at a temperature of 90 ° C to 110 ° C. Following the first section of contact carried out at atmospheric pressure (“wet bleaching”), the second stage of the bleaching process is carried out under reduced pressure, for example at 2 to 3 kPa (20-30 mbar) (“dry” bleaching").

  Conventional methods for purifying glyceride oils typically include a step of neutralizing FFA with a strong base, such as sodium hydroxide or potassium hydroxide (corresponding to the so-called “chemical purification” method). Alternatively, deoxidation can be accomplished by adjusting the deodorization parameters, thereby ensuring that volatile FFA is removed in that step (so-called “physical purification” method). Disadvantages of the step of neutralizing FFA (“chemical purification”) are associated with undesired saponification, low triglyceride content, and soap formation can result in considerable neutral oil loss as a result of emulsification. is there. The basic ionic liquid treatment that forms part of the refining process of the present invention is effective in neutralizing FFAs in oil and takes the entire conventional neutralizing step used in chemical refining processes. Can be replaced. Advantageously, the treatment with basic ionic liquid has the advantage that it does not result in saponification of the neutral oil. Thus, in a preferred embodiment of the invention, the purification method does not include a step of neutralizing with an inorganic base (eg, sodium hydroxide).

  The FFA contained in the oil can be neutralized by contact with a basic ionic liquid to produce a quaternary ammonium-FFA salt. In a preferred embodiment, the amount of basic ionic liquid used in the contacting step is at least stoichiometric with the molar amount of FFA contained in the oil. For example, the molar ratio of basic ionic liquid to FFA in oil may be 1: 1 to 10: 1, or 1.5: 1 to 5: 1. The FFA content of a glyceride oil can be measured prior to treatment with a basic ionic liquid using common titration techniques known to those skilled in the art. For example, titration with sodium hydroxide using a phenolphthalein indicator can be used to measure the FFA content of glyceride oil.

In a preferred embodiment, the basic ionic liquid is selected to provide linear C ₁₂ -C ₁₈ FFA to the low melting point fatty acid salt. Particularly preferred basic ionic liquids use such FFAs with melting points below 100 ° C. to form salts. Such salts can be conveniently separated from the treated glyceride oil using the liquid-liquid separation techniques described herein.

  As known to those skilled in the art, the deodorizing step is such as to evaporate or extract volatile components such as FFAs, aldehydes, ketones, alcohols, hydrocarbons, tocopherols, sterols, and plant sterols. This corresponds to a stripping process in which an amount of stripping agent is typically passed through the oil in the distillation apparatus by direct injection for a period of time under reduced pressure. The stripping agent is preferably steam, but other agents such as nitrogen may be used. The amount of stripping agent suitably used is about 0.5% to about 5% by weight of the oil.

  The temperature range of the deodorizing step of the purification method according to the present invention is preferably 160 ° C to 270 ° C. When referring to the temperature of the deodorizing step herein, it refers to the temperature at which the oil is heated before it is exposed to the stripping agent. The pressure range of the deodorizing step is suitably 0.1 to 0.4 kPa (1 to 4 mbar), preferably 0.2 to 0.3 kPa (2 to 3 mbar). A suitable time segment for the deodorizing step is typically 30 to 180 minutes, such as 60 to 120 minutes, or 60 to 90 minutes.

  One skilled in the art can determine the preferred length of the deodorizing step by analyzing the properties and composition of the glyceride oil, for example, by measuring the p-anisidine number (AnV) of the oil. The p-anisidine value of oil is a measurement of its oxidation state, more specifically, mainly aldehydes such as 2-alkenals and 2,4-dienals, but the second oxidation product contained in the oil. Provides information on the concentration of. Thus, the p-anisidine number (AnV) provides an indication of the concentration of oxidation product that is to be removed by the deodorizing step. For example, if AnV is less than 10, preferably less than 5, as determined by AOCS official method Cd 18-90, a sufficient deodorizing step can be accomplished.

  Additionally or alternatively, the amount of aldehyde and ketone components of the oil, typically associated with the odor of the crude oil, can be measured, thereby determining whether sufficient deodorization has occurred . Typical volatile odor aldehyde and ketone components of crude or odorous palm oil include acetaldehyde, benzaldehyde, n-propanal, n-butanal, n-pentanal, n-hexanal, n-octanal, n- Nananal, 2-butenal, 3-methylbutanal, 2-methylbutanal, 2-pentanal, 2-hexanal, 2E, 4E-decadienal, 2E, 4Z-decadienal, 2-butanone, 2-pentanone, 4 -Methyl-2-pentanone, 2-heptanone, 2-nonanone. Preferably, each of these components is present in the deodorized oil in an amount of less than 3 mg / kg of oil, more preferably less than 1 mg / kg of oil, and most preferably less than 0.5 mg / kg of oil.

  The amount of aldehyde and ketone can be easily measured by chromatographic methods, for example, GC-TOFMS or GCxGC-TOFMS. Alternatively, aldehyde and ketone derivatization can be used to improve chromatographic analysis. For example, it is known that aldehydes and ketones can be derivatized with 2,4-dinitrophenylhydrazine (DNPH) under acidic conditions. This reagent does not react with the carboxylic acid or carboxylic acid ester and therefore the analysis is not affected by the presence of such components in the glyceride oil sample. Following derivatization, the total amount of aldehydes and ketones present in the sample can be quantified by HPLC-UV analysis.

  Conventional deodorization temperatures typically exceed 220 ° C, for example 240 ° C to 270 ° C, typically 60-90 minutes. As is possible with the method of the present invention, when lower temperatures than conventional, for example 160 ° C to 200 ° C, are used for the deodorizing step, the time interval of the deodorizing step is longer to ensure sufficient deodorization. However, it still consumes less energy than a conventional deodorizing step performed at a higher temperature, eg, 240 ° C. to 270 ° C., in a shorter time.

  In a preferred embodiment, the same or shorter time interval of the conventional deodorizing step is used in combination with a temperature lower than the conventional deodorizing temperature, but as a result of the previous basic ionic liquid treatment. A certain degree of deodorization is achieved. In other preferred embodiments, when conventional temperatures, such as 240 ° C. to 270 ° C., are used in the deodorizing step included in the purification method of the present invention, the time interval of the deodorizing step is that conventionally used. It can be shortened compared with it, yet an equivalent level of deodorization is achieved as a result of the previous basic ionic liquid treatment.

  Therefore, the basic ionic liquid treatment also has the advantage that the energy consumption during the next deodorizing step can be reduced. In addition, advantageously, side reactions that can lead to undesirable sensory irritation properties of the oil, or undesirable potential harm, by lowering the temperature of the heat exposure during the deodorizing step or by shortening the time segment. By-product formation can also be reduced.

  In a particularly preferred embodiment, when the at least one further purification step according to the method of the invention comprises a deodorizing step, the temperature of the deodorization is 160 ° C to 200 ° C, more preferably 170 ° C to 190 ° C. Preferably, the time interval during which deodorization is performed at these temperatures is 30 to 150 minutes, more preferably 45 to 120 minutes, and most preferably 60 to 90 minutes.

  The basic ionic liquid treatment according to the method of the present invention can suitably be applied to a metal-containing crude glyceride oil that has not undergone any prior refining steps following oil extraction. Alternatively, the method of the invention can be applied to glyceride oil that has undergone at least one additional purification step prior to treatment with the basic ionic liquid. Preferably, the at least one additional purification step is selected from a bleaching step and / or a degaming step.

  Advantageously, it has been found that the basic ionic liquid treatment that forms part of the process of the present invention can at least partially degum the oil and remove the pigment. That means that the range of degaming and bleaching steps can be reduced, for example in terms of processing time or material. As described above, the basic ionic liquid treatment that forms part of the method of the present invention eliminates the step of neutralizing the separated FFA used in the chemical purification method. On the other hand, the basic ionic liquid treatment that forms part of the method of the present invention can also reduce the energy consumption of the deodorizing step.

  The basic ionic liquid treatment used in accordance with the present invention can significantly contribute to the material costs associated with glyceride oil purification, eliminating the need for ion exchange resin membranes and ultrafiltration membranes to remove metal contaminants. Intended to be. Thus, in a preferred embodiment, the purification method described herein does not include treatment of glyceride oil with ion exchange resin membranes or ultrafiltration membranes.

  In some embodiments, the basic ionic liquid used in step (i) that is contacted to recycle the basic ionic liquid to the purification method of the present invention, if necessary, is regenerated by a regenerating method. It can be regenerated from an ionic compound containing organic quaternary ammonium cations separated in step (ii) (this species varies). For example, the regeneration method can include exchanging anions or cations to obtain a basic ionic liquid containing the desired basic anion described above.

In one embodiment, the method of playing is
(A) contacting the choline-FFA salt with carbonic acid;
(B) producing a basic ionic liquid that is choline bicarbonate from a choline-FFA salt, comprising obtaining choline bicarbonate from the reaction mixture.

Preferably, step (a) is performed by contacting an aqueous solution comprising a choline-FFA salt with CO ₂ (eg, by bubbling CO ₂ into the aqueous solution).

  Preferably, step (b) is carried out by contacting the mixture of step (a) with a solvent that is miscible with choline bicarbonate and separating the solvent from choline bicarbonate.

  In another aspect, the present invention also provides a composition comprising a metal-containing glyceride oil and a basic ionic liquid, as described above, provided that the glyceride oil does not comprise palm oil. To do. The total concentration of metals in the composition is 10 ppm to 10000 ppm. Preferred embodiments of other aspects of the invention relating to the anionic and cationic properties of the basic ionic liquid apply equally to this aspect of the invention. For example, the basic ionic liquid is most often choline bicarbonate.

  In a further aspect, the present invention also provides the use of the basic ionic liquid described above for reducing the total metal concentration of the metal-containing glyceride oil by contacting the oil with the basic ionic liquid, Use is also provided, provided that it does not contain palm oil. The basic ionic liquid can be used in neat form or with a solvent, as described above. A basic ionic liquid can be used to reduce the concentration of any metal described herein in glyceride oil.

  Preferably, the metal-containing glyceride oil is treated with a basic ionic liquid before subjecting it to heating the glyceride oil as part of its purification. The step of heating may correspond to, for example, heating the oil to a temperature above 150 ° C., to a temperature above 200 ° C., or even above 250 ° C. Thus, the heating step can form part of the deodorizing step. As mentioned above, the presence of iron can adversely affect the sensory irritation properties of the oil if it is present in a sufficient amount during exposure of the oil to heat, such as during a deodorizing step. . Therefore, it is beneficial to remove substantial amounts of iron and other oxidation-promoting metals by treatment with a basic ionic liquid prior to the heating step.

  Preferred embodiments of the other aspects of the present invention relating to the anionic and cationic characteristics of the basic ionic liquid and the characteristics of the glyceride oil apply equally to this aspect of the present invention. For example, the basic ionic liquid is most preferably choline bicarbonate.

  The embodiments of the present invention described above can be combined with any other compatible embodiment to form further embodiments of the present invention. As will be appreciated by those skilled in the art, all aspects of the present invention can be applied to the processing and refining of palm oil or glyceride oil mixtures comprising palm oil. In certain embodiments, the present invention also extends to a method as described herein, wherein the glyceride oil comprises or consists of palm oil, further comprising the regenerating step described above. .

The invention will now be illustrated by the following examples.
[Example]

General Sample Preparation Procedure for ICP-OES Analysis 1 Carbonize 160 mg of oil sample at 800 ° C. for 6 hours.
2 Dissolve the carbonized sample in aqua regia to dissolve inorganic matter.
3 Add hydrogen peroxide to oxidize / dissolve organic matter.
4 Dilute the resulting solution to 25 ml with water.
5 A sample of this solution is used for ICP-OES analysis.

Effect of ionic liquid treatment on metal concentration of oil

Metal Removal by Ionic Liquid Treatment of Soybean Oil A purified commercial soybean oil sample (23.4 g) was added to Fe [NO ₃ ] ₃ (˜about 445 ppm), CuI (˜about 0.3 ppm), Na ₂ CrO ₄ . 4H ₄ O (˜about 0.9 ppm), and NiBr ₂ . Doped with 3H ₃ O (0.2 ppm). Choline bicarbonate (0.9 g, 80 w / w% in H ₂ O, Sigma-Aldrich UK) was added to the oil and the mixture was stirred at room temperature for about 12 hours. A small sample of oil (160 mg) was removed and prepared for ICP-OES analysis as described in the general method above. The results of the analysis are shown in Table 1 below.

Metal removal by ionic liquid treatment of olive oil A purified commercial olive oil sample (23.4 g) was added to Fe [NO ₃ ] ₃ (˜about 445 ppm), CuI (˜about 0.3 ppm), Na ₂ CrO ₄ . 4H ₄ O (˜about 0.9 ppm), and NiBr ₂ . Doped with 3H ₃ O (0.2 ppm). Choline bicarbonate (0.9 g, 80 w / w% in H ₂ O, Sigma-Aldrich UK) was added to the oil and the mixture was stirred at room temperature for about 12 hours. A small sample of oil (160 mg) was removed and prepared for ICP-OES analysis as described in the general method above. The results of the analysis are shown in Table 2 below.

  According to the results of Tables 1 and 2, the ionic liquid treatment according to the present invention can substantially reduce the concentration of the metal in the glyceride oil. In Example 1 and Example 2, the reduction rate% of iron is 94% and 97%, respectively. On the other hand, for both Example 1 and Example 2, as a result of the ionic liquid treatment, the concentrations of copper, chromium, and nickel were reduced to sub-ppm.

It is also noteworthy that the oil used in the above example corresponds to a refined oil that has already been degummed before doping with metal. Thus, it has been shown that the ionic liquid treatment according to the present invention at least partially degums glyceride oil, but according to the above results, metal removal is a degaming step as a means to accomplish metal removal. Do not depend. Thus, the basic ionic liquid treatment can be applied at various stages of the overall method.

Claims (33)

A method for removing metals from metal-containing glyceride oils,
(I) contacting a metal-containing glyceride oil containing a metal having a total metal concentration of 10 ppm to 10,000 ppm with a basic ionic liquid to produce a treated glyceride oil, wherein the basic ionic liquid is a hydroxide ion, From alkoxide ion, alkyl carbonate ion, bicarbonate ion, carbonate ion, serinate ion, prolineate ion, histinate ion, threoninate ion, valinate ion, aspartate ion, taurinate ion, and lysinate ion Said producing step comprising a selected basic anion, as well as an organic quaternary ammonium cation;
(Ii) after bringing the glyceride oil into contact with the basic ionic liquid, separating the treated glyceride oil from the ionic compound containing the organic quaternary ammonium cation, Said separating step having a reduced metal concentration compared to said glyceride oil contacted in step (i),
However, the said method that the said glyceride oil contacted does not contain palm oil. A method for purifying a metal-containing glyceride oil, the method comprising:
(I) a step of bringing a metal-containing glyceride oil into contact with a basic ionic liquid to produce a treated glyceride oil, wherein the basic ionic liquid is a hydroxide ion, an alkoxide ion, an alkyl carbonate ion, or a bicarbonate ion A basic anion selected from carbonate ion, serinate ion, prolinate ion, histinate ion, threoninate ion, valinate ion, aspartate ion, taurinate ion, and ricinate ion; Said producing step comprising a quaternary ammonium cation;
(Ii) after bringing the glyceride oil into contact with the basic ionic liquid, separating the treated glyceride oil from the ionic compound containing the organic quaternary ammonium cation, The separating step having a reduced metal concentration compared to the glyceride oil contacted in the generating step (i);
(Iii) subjecting the treated glyceride oil after the separating step (ii) to at least one further purification step;
However, the said method that the said glyceride oil contacted does not contain palm oil.   At least one further purification step is selected from a degaming step, a bleaching step, a dewaxing step, a decolorizing step, and a deodorizing step, preferably the at least one further purification step comprises a deodorizing step. The method of claim 2 comprising.   At least one further purification step preferably involves a steam stripping step carried out at a temperature of 160-270 ° C., preferably at a temperature of 160 ° C.-240 ° C., more preferably at a temperature of 170 ° C.-190 ° C. 4. A method according to claim 3, comprising the step of deodorizing.   The method according to any of claims 2 to 4, further comprising at least one additional purification step of the glyceride oil performed prior to the treatment with the basic ionic liquid of step (i). Wherein the at least one additional purification step is selected from a bleaching step and / or a degaming step.   The method according to any of claims 2 to 4, wherein the at least one further purification step (iii) comprises a deodorizing step, wherein the method does not comprise a degaming step and / or a bleaching step. Said method.   The method according to any one of claims 2 to 6, wherein the total concentration of metals in the glyceride oil before contacting in step (i) is 10 ppm to 10000 ppm, preferably 50 ppm to 5000 ppm, more preferably 100 ppm to 2000 ppm. .   The treated glyceride oil separated in step (ii) has a metal concentration of at least 50 wt%, preferably at least 75 wt% lower than the metal-containing glyceride oil contacted in step (i). 8. The method according to any one of 7.   9. The method according to any of claims 1 to 8, wherein the metal of the metal-containing glyceride oil is included in the form of free metal ions and / or as one or more metal-containing compounds or metal-containing complexes.   The glyceride oil contacted in step (i) comprises one or more metals selected from alkali metals, alkaline earth metals, transition metals, and post-transition metals, preferably in step (i) The glyceride oil is selected from lithium, sodium, potassium, beryllium, magnesium, calcium, strontium, barium, chromium, manganese, iron, cobalt, nickel, copper, zinc, cadmium, mercury, aluminum, tin, and lead The method according to claim 1, comprising one or more metals.   The glyceride oil contacted in step (i) comprises one or more metals selected from sodium, potassium, calcium, magnesium, strontium, barium, iron, zinc, nickel, copper, chromium, and aluminum; Preferably, the glyceride oil contacted in step (i) comprises one or more metals selected from strontium, barium, iron, copper, chromium and nickel, most preferably step (i) The method of claim 10, wherein the glyceride oil contacted with comprises iron and / or copper.   The method according to any of claims 1 to 11, wherein the ionic compound separated in step (ii) comprises one or more metal ions.   The method according to claim 1, wherein the ionic compound separated in step (ii) comprises an anion of a free fatty acid.   The method according to any of claims 1 to 13, wherein the contacting step (i) is performed at a temperature below 80 ° C, preferably at a temperature of 25-65 ° C, more preferably at a temperature of 35-55 ° C. . An organic quaternary ammonium cation in a basic ionic liquid
[N (R ^a ) (R ^b ) (R ^c ) (R ^d )] ⁺
Wherein R ^a , R ^b , R ^c , and R ^d are each independently selected from a linear or branched C ₁ -C ₈ alkyl group, or a C ₃ -C ₆ cycloalkyl group. Or any two of R ^a , R ^b , R ^c , and R ^d combine to form an alkylene chain — (CH ₂ ) _q —, where q is 3-6, and the alkyl group or the cycloalkyl _group, C 1 -C _{4 alkoxy,} C 2 -C _{8 alkoxyalkoxy,} C 3 -C _{6 cycloalkyl, -OH, -SH, -CO 2 (} C 1 -C 6) alkyl, and -OC (O) It may be substituted with 1 to 3 groups selected from (C ₁ -C ₆ ) alkyl, for example, with 1 to 3 —OH groups.
The method according to claim 1, wherein the method is selected from: An organic quaternary ammonium cation in a basic ionic liquid
[N (R ^a ) (R ^b ) (R ^c ) (R ^d )] ⁺
(Wherein R ^a , R ^b , R ^c , and R ^d are each independently selected from a linear or branched C ₁ -C ₈ alkyl group, and the alkyl group is C ₁ -C _{4 alkoxy,} C 2 -C _{8 alkoxyalkoxy,} C 3 -C _{6 cycloalkyl, -OH, -SH, -CO 2 (} C 1 -C 6) alkyl, and _{-OC (O) (C 1 -C} 6) (It may be substituted with 1 to 3 groups selected from alkyl, for example, with 1 to 3 —OH groups.)
The method of claim 15, wherein the method is selected from: An organic quaternary ammonium cation in a basic ionic liquid
[N (R ^a ) (R ^b ) (R ^c ) (R ^d )] ^{+
(Wherein, R a, R b, R} c, and ^{R d} are each _{independently,} C 1, _{C 2,} and alkyl of _{C 4,} linear or branched _C 1 -C ₄ alkyl And at least one of R ^a , R ^b , R ^c , or R ^d is substituted by one —OH group.
The method of claim 16, wherein the method is selected from: The organic quaternary ammonium cation is choline,


The method of claim 17.   The method according to any one of claims 1 to 18, wherein the basic anion is selected from an alkyl carbonate ion, a bicarbonate ion, and a carbonate ion, and preferably the basic anion is a bicarbonate ion. The basic ionic liquid used to contact the glyceride oil in step (i) is choline bicarbonate,


The method of claim 19.   The method according to any one of claims 1 to 18, wherein the basic anion is selected from a hydroxide ion and an alkoxide ion, and preferably the basic anion is a hydroxide ion. The basic ionic liquid used to contact the glyceride oil in step (i) is choline hydroxide,


The method of claim 21.   The glyceride oil is brought into contact with a liquid containing a solvent such as a basic ionic liquid and an aqueous solvent, and the concentration of the basic ionic liquid in the liquid is 15% by weight to 90% by weight. The method of crab.   The glyceride oil is brought into contact with a liquid containing a solvent such as a basic ionic liquid and an aqueous solvent, and the concentration of the basic ionic liquid in the liquid is 50 wt% to 90 wt%, preferably 75 wt% to 85 wt%. The method according to claim 19 or 20, wherein   A glyceride oil is brought into contact with a liquid containing a solvent such as a basic ionic liquid and an aqueous solvent, and the concentration of the basic ionic liquid in the liquid is 15 wt% to 60 wt%, preferably 40 wt% to 50 wt%. 23. The method of claim 21 or 22, wherein the method is%. 21. The method of claim 20, wherein the contacted glyceride oil comprises FFA and the ionic compound separated from the glyceride oil is a choline-FFA salt, wherein the method comprises ions separated from the oil to be treated. Regenerating a choline bicarbonate basic ionic liquid from the compound, the regenerating step comprising:
(A) contacting the choline-FFA salt with carbonic acid;
(B) obtaining choline bicarbonate from the reaction mixture. Step step of reproducing (a) is carried out by contacting an aqueous solution containing choline -FFA salts and CO _2, The method of claim 26.   The glyceride oil is a vegetable oil, preferably the vegetable oil is selected from coconut oil, corn oil, cottonseed oil, peanut oil, olive oil, rapeseed oil, rice bran oil, safflower oil, soybean oil, and sunflower oil, or mixtures thereof 28. A method according to any of claims 1-27.   A composition comprising a metal-containing glyceride oil and a basic ionic liquid, provided that the glyceride oil does not contain palm oil, and the total metal concentration in the composition is 10 ppm to 10000 ppm, and the base Ionic liquid is hydroxide ion, alkoxide ion, alkyl carbonate ion, bicarbonate ion, carbonate ion, serinate ion, prolineate ion, histinate ion, threoninate ion, valinate ion, aspartate ion , A taurinate ion, and a basic anion selected from ricinate ions, and an organic quaternary ammonium cation.   30. The composition of claim 29, wherein the basic ionic liquid is as in any of claims 15-21.   Use of the basic ionic liquid to reduce the total metal concentration of the metal-containing glyceride oil by contacting the oil with the basic ionic liquid, provided that the glyceride oil does not contain palm oil, The basic ionic liquid is hydroxide ion, alkoxide ion, alkyl carbonate ion, hydrogen carbonate ion, carbonate ion, serinate ion, prolineate ion, histinate ion, threoninate ion, valinate ion, asparagine. Said use comprising a basic anion selected from nate ion, taurate ion and ricinate ion, and an organic quaternary ammonium cation.   The glyceride oil is a vegetable oil, preferably the vegetable oil is selected from coconut oil, corn oil, cottonseed oil, peanut oil, olive oil, rapeseed oil, rice bran oil, safflower oil, soybean oil, and sunflower oil, or mixtures thereof 32. Use according to claim 31, wherein:   Use according to claim 31 or 32, wherein a basic ionic liquid is used to reduce the concentration of any of the metals according to claim 10 or 11.