JP5620818B2 - Process for producing fatty acids and fatty acid esters - Google Patents

Description

  The present invention relates to a method for producing a fatty acid, a fatty acid ester or a mixture thereof from a raw material containing soap and the use of the mixture produced in the method.

  Biodiesel fuel is mainly a methyl ester of a fatty acid produced by a transesterification reaction between a long-chain fatty acid and an alcohol (methanol). Fatty acid esters of natural fats mainly consist of triglycerides, and water-soluble glycerol that is unacceptable as a biodiesel fuel is released during the transesterification reaction. In addition, alcohol (methanol) and fatty acid salts (soap) mixed with an aqueous solution of glycerol are released during this process. Fraction containing glycerol, alcohol and soap has a high energy content, especially in connection with soap. Theoretically, 10% by weight of glycerol is produced from triglycerides.

  The proportion of soap is highly dependent on the production conditions and increases to tens of percent of the original total amount of triglycerides. Since the soap compound is dispersed and partially dissolved in the aqueous solution of glycerol produced, it is difficult to separate the soap compound from the aqueous solution. Soap breaks down the phase between fat-soluble fatty acid esters and water-soluble glycerol, producing emulsions with different degrees of emulsification, which, in large-scale manufacturing processes, presents the challenges associated with separation techniques. Bring. Removal of alcohol such as methanol requires high-cost vacuum distillation.

  Therefore, it can be concluded that the most energetic part of the raw material is not fully utilized in the production method of biodiesel fuel by the above-mentioned method in modern technology. Purification to increase the utility value of the compounds produced in such production processes is significantly uneconomical in relation to the necessary purification steps.

  The above reasons are a major factor, and no cost effective solution has been found to effectively utilize an aqueous mixture of glycerol, soap and alcohol (methanol).

  No economically advantageous solution is provided as a business for converting multi-component mixtures containing glycerol as a component into commercial products. The seriousness of this technical deficit has become particularly emphasized as the interest directed towards renewable energy source raw materials along with fossil raw materials has increased.

  The present invention has been made to solve the above-mentioned problems in the field.

  The present invention relates to a method for producing a fatty acid, a fatty acid ester or a mixture thereof from a raw material containing soap.

  The invention relating to the production method according to the present invention is characterized by the invention-specific matters described in claim 1 of the claims.

  On the other hand, the invention according to the use according to the present invention is characterized by the invention-specific matters of claims 15 and 16 of the claims.

It is a flowchart which shows the main implementation steps of the manufacturing method by this invention.

  The present invention is a novel problem relating to a process for producing esters of fatty acids from fats by treating glycerolipid-containing fats with alkali metal alkoxides according to established methods using methanol or other short chain alcohols. A simple solution. In this process, alkali metal salts (soaps) of glycerol and other alcohols and fatty acids are produced. Glycerol and soap in the mixture reduces the utilization of the total carbon contained in the original fat used in the process, thereby reducing the economic efficiency of the process. Compared to pure glycerol, the inherent disadvantage of using glycerol produced in the production of biodiesel fuel is that it contains water, soap and toxic methanol or other short chain alcohols as impurities. It is to be.

  It is known that the presence of soap in water or a water-insoluble oil-containing mixture prevents mutual separation of the aqueous and oil phases. In aqueous solutions of impure polyhydric alcohols, soaps break the phase between lipids formed from fatty acid esters and water, making it difficult to separate these phases, and even at best, , Water and other ingredients that exhibit higher solubility in the aqueous phase.

  The advantage of the present invention resides in an integrated unit operation entity, by which the ester produced from the hydrocarbon chain-containing fatty acid and the short chain alcohol is released from the transesterification reaction of the organic fat. Can be removed from the secondary stream of impure glycerol, which is difficult to economically utilize. The equipment used in this method is a simple equipment, and the techniques related to manufacturing and usage using the equipment are known. The method according to the invention is not restricted to the production scale and can be easily adapted according to the scale.

  In particular, according to the present invention, it is possible to recover soap rich in energy and recycle it to fatty acid alcohol esters or free fatty acids. The technical / economic advantages of the method of the present invention are as follows. That is, by using this method, the carbon in the fraction which is a fraction composed of a compound having an alcohol group and contains impurities can be converted into a unit operation requiring energy (for example, a heating operation) or a pressure unit operation. The use of chemicals of this kind that can be incorporated into the internal circulation in the process of the present invention and that are only functionally required to make full use to produce fatty acid esters and fatty acids. Can do.

  Compared to the prior art, the present invention, in all respects, more efficiently meets the principles of sustainable development by enhancing the full availability of the raw material and reducing the need to use another raw material. The method of the present invention consists of a functional entity having the necessary conditions to update the production costs of fatty acids and their alcohol esters to a level acceptable to the consumer.

  Since no useful solution has been found to make effective use of a mixture containing soap, polyhydric alcohol and monohydric alcohol, in order to use these components separately, Should be separated.

The inventor has found the following. That is, soap easily precipitates from a glycerol-containing oil-water-alcohol emulsion, recovers the naturally separated precipitate, and then conducts a methylation reaction of the precipitate to produce the final biodiesel fuel (fatty acid From the soap. Other esters can also be produced according to the present invention. In this connection, it is already known that the soap component in the impure glycerol fraction is advantageous as a feedstock for biodiesel fuel. Thus, the soap can be separated almost quantitatively from the other components. The remaining glycerol solution without soap can be used separately.

  Therefore, the present invention relates to a method for producing a fatty acid, a fatty acid ester, or a mixture thereof from a raw material containing soap (preferably, a raw material containing alcohol and soap). The alcohol is preferably methanol, ethanol, 1-propanol or a polyhydric alcohol (most preferably glycerol).

  The term “soap” means a salt of a fatty acid.

  In particular, the present invention relates to a method comprising the step of generating a mixture containing an insoluble phase and a liquid phase by adding a metal ion generating agent to the starting material. After separating the insoluble phase from the liquid phase, acid is added to the insoluble phase. After separating the insoluble phase, it is preferable to repeat the operation of adding the ion generating agent for precipitation into the liquid phase, and the resulting precipitate is treated as described above. This process can be repeated until the formation of precipitates is substantially reduced.

  Fatty acids are produced by adding acid into the combined insoluble phases. The fatty acid may be recovered and used as it is, or a fatty acid ester is produced by adding a monohydric alcohol and an acidic catalyst to the fatty acid. In this case, two phases of an aqueous phase and an organic phase are formed. These phases are separated from each other, preferably both are collected. The organic phase contains fatty acid esters. If desired, an aqueous phase and an organic phase are formed by adding a monohydric alcohol and an acidic catalyst into the insoluble phase without separating and recovering the fatty acid. In this case, the organic phase contains a fatty acid ester.

  Therefore, the fatty acid may be used as it is, or a fatty acid ester suitable for biodiesel fuel can be produced from the fatty acid by treating the fatty acid with a monovalent short chain alcohol. The procedures required for the method described herein can be performed by those skilled in the art without the need for complex equipment, and the additives (reagents) required for the method are known and safe. And has an established final form of use.

In general, the present invention includes a method based primarily on inherent processes, i.e., where long chain fatty acids or fatty acid esters are produced from organic soaps or mixtures thereof. In this case, the term “long chain” means at least a C ₄ hydrocarbon chain, ie a hydrocarbon chain having at least 4 carbon atoms. Preferably, the hydrocarbon chain is _C 10 _{-C 20,} more preferably have a length of _C 12 _{-C 20.}

The method according to the invention comprises the following steps (i) and (ii):
(I) A water-soluble or water-dispersible soap formed from fatty acids is converted into a form of water-insoluble soap by using a metal ion generator, and then (ii) a water-insoluble soap formed from fatty acids is converted into alcohol Is converted to free fatty acids by esterification to alcohol esters of fatty acids or by acid treatment.

According to a preferred embodiment of the invention, the method according to the invention comprises the following steps (i) to (vi):
(I) Optionally, the pH value is adjusted to 3-8, preferably 6-8, by adding an acid, preferably an organic acid, more preferably acetic acid, formic acid or lactic acid to the starting material,
(Ii) an amount that precipitates at least 40% of the soap into the mixture as a solid or aqueous solution (preferably an amount that produces a stoichiometric amount of metal ions relative to the amount of soap, most preferably stoichiometrically). 5 to 10% by weight excess) metal ion generator, such as an inorganic salt of an alkaline earth metal, preferably the inorganic salt producing Ca ²⁺ or Mg ²⁺ , more preferably calcium chloride, magnesium chloride (most suitably , Calcium chloride) to form an insoluble phase and a liquid phase [in this case the insoluble phase contains soap, the liquid phase is preferably a polyhydric alcohol (preferably glycerol) and a monohydric alcohol (preferably Is methanol, ethanol or 1-propanol or mixtures thereof, most suitably methanol)],
(Iii) from the first liquid phase to the insoluble phase (in which the soap is insoluble soap, preferably by filtration, decanting or other methods commonly used for precipitation recovery) To be separated)
(Iv) generating a fatty acid or fatty acid mixture by adding an acid (preferably hydrochloric acid or sulfuric acid) to the insoluble phase;
(V) An organic phase containing a fatty acid ester or a fatty acid ester mixture and an aqueous solution containing water and an inorganic salt by performing acid treatment using a mixture of an acidic catalyst (preferably hydrochloric acid or sulfuric acid) and an alcohol, if desired. Phase is formed and then (vi) the organic phase is collected.

  According to another preferred embodiment of the invention, the starting material used in the process according to the invention is a mixture which is a fraction produced as a result of the transesterification of lipids.

  According to a particularly preferred embodiment, the molar amount of monohydric alcohol to be added to the fatty acid fraction is at least 40%, preferably equivalent, relative to the molar amount of organic substance.

  Particularly preferably, the process according to the invention comprises the step of removing any solid components from the starting material by filtration. After this, the acidity of the starting material is adjusted with the required amount of acid (preferably acetic acid, formic acid or lactic acid, most suitably acetic acid).

Soluble soap present in the starting material that has been subjected to filtration treatment is added to the mixture by a metal ion generator (preferably an inorganic salt of a divalent alkaline earth metal, more preferably an inorganic salt of Ca ²⁺ , most preferably CaCl ₂ ) is converted to an insoluble soap. Most suitably, a large amount of water can be avoided by adding the salt as a solid. The mixing time is controlled until the precipitation reaction is substantially stopped. When the solids are separated from the liquid phase, for example by filtration, a wet “soap cake” remains. According to a particularly preferred embodiment, the soap cake is subjected to a drying treatment, the residual amount of water in the dried precipitate is generally 5% by weight, preferably 0.1 to 4% by weight, most suitably 0.1 to 2.5% by weight.

  The resulting insoluble fraction (precipitate) is separated from the liquid fraction by filtration, decanting or other methods commonly used for precipitation recovery. The acid treatment of the insoluble fraction is preferably carried out by using hydrochloric acid as an aqueous solution (most suitably 0.5-10% aqueous solution). A sufficient amount of acid is added to liberate the fatty acids.

  According to a particularly preferred embodiment of the invention, the acid treatment and esterification are carried out as acid-catalyzed esterification or by gradual esterification. Preferably, the soap precipitate is treated with HCl-methanol at a temperature above the boiling point of methanol, more preferably above 65 ° C, most suitably at 80 ° C. As a result of this treatment, a two-phase mixture is formed and the second phase, ie the organic phase, contains the fatty acid methyl ester, which is collected. Preferably, the phase containing the salt formed in the esterification is added to the starting material. Accordingly, the aqueous solution containing the inorganic salt produced in the esterification can be recycled to the soap mineral salt treatment step.

Compounds added at different steps of the process, for example divalent alkaline earth metal salts such as CaCl ₂ or by-product fractions formed by them, apart from NaCl, are completely separated from the reaction process. Rather, it is preferably recycled during the reaction process or forms an economically useful separate fraction to improve the overall economics of the process.

  According to a particularly preferred embodiment of the invention, the fatty acids produced are used to produce alcohol esters of fatty acids. More preferably, these fatty acid esters and the fatty acid esters produced according to the invention are further used in the production of biofuels, for example biodiesel fuels. Most advantageously, the product according to the invention is fed in the process of producing a feedstock in the esterification of fatty acids or hydroprocessing of vegetable or animal lipids, in particular so-called “HVO (hydrogenated vegetable oil)”. Suitable as raw material.

  According to a preferred embodiment of the invention, the esters according to the invention are used in the production of biodiesel or renewable diesel fuel. In this connection, fatty acids can be used for other fuels similar to diesel fuel.

  In this context, the starting material used in the process of the invention is preferably a methanol-containing glycerol fraction produced, for example, in the production of biodiesel fuel, the fraction containing at least about 2-10% soap. Obtained from.

  Since water causes the formation of soap in the transesterification reaction, the presence of water is not harmful in the present invention, but the content of water and monohydric alcohol is minimized in the above-mentioned transesterification reaction. It is suppressed. The methanol-containing glycerol fraction is mixed with less than 20%, preferably 2-10% water. Such a water content is a preferred amount in the starting material used in the process according to the invention.

  The term “biodiesel” is, according to the EU-directive 2003/30 / EY, “methyl esters produced from vegetable or animal oils, It means “the methyl ester having quality”. Biodiesel fuel therefore consists of fatty acid esters.

  On the other hand, the term “renewable diesel” means hydrotreated animal fat, vegetable fat or microbial fat. In this case, the term “microbial fat” means fat derived from bacteria, yeast, mold, algae or other microorganisms.

  The fatty acids and fatty acid esters produced according to the present invention can be used to produce biofuels. These compounds can be used as biofuels or can be mixed with other ingredients. The acid structure or ester structure of these compounds can be disrupted by methods known in the art, and by saturating double bonds in these compounds, n-paraffin products are obtained, The product can be mixed with other ingredients.

Example 1: Preparation of fatty acid ester A secondary fraction obtained in the production of biodiesel fuel using rapeseed oil, weighing 0.5 liter of this fraction containing glycerol and soap, and then under stirring Solid calcium chloride was added into the fraction until no precipitate formed (0.9 mol). The soap precipitate was separated from the liquid glycerol fraction by a filtration treatment, and the precipitate was subjected to a water washing treatment, followed by a drying treatment to obtain a substantially dry precipitate (171 g).

  0.54 g of the obtained precipitate was weighed, and a mixture of methanol and hydrochloric acid (a mixture composed of 45.8% methanol and 54.2% hydrochloric acid) was added to the precipitate. The resulting mixture was heated in a closed vessel at 80 ° C. for 1.5 hours and the resulting fatty acid methyl ester (1 ml) was separated from the mixture by conventional separation methods.

Example 2 Production of Fatty Acid and Esterification of the Fatty Acid By treating the precipitate obtained as described above with hydrochloric acid, the pH value of the aqueous layer was adjusted to an acidic value (pH = 2). The resulting mixture was heated to 62 ° C. to separate the fatty acid-containing surface layer. Salt was removed from the surface layer by subjecting the surface layer to a water washing treatment. Water remaining together with the fatty acid and fatty acid remaining in the surface layer after the water washing treatment was removed by a drying treatment using a dehydrating agent to leave the fatty acid mixture in the surface layer.

  11.4 g of the obtained fatty acid mixture was weighed, and methanol (4-fold molar amount) and HCl gas as a catalyst were added to the mixture. The resulting oil layer was washed with a methanol / water mixture, and then washed with water until the wash water became neutral, and then the oily ester layer (6 ml) was separated from the oil / aqueous solution mixture.

  The resulting fatty acid mixture and the corresponding fatty acid ester mixture are, for example, well suited for producing diesel fuel.

Claims (23)

A method for producing a fatty acid, a fatty acid ester or a mixture thereof from a starting material containing alcohol and soap, the method comprising the following steps (i) to (iii):
(I) adding a metal ion generator to the starting material to produce a mixture comprising an insoluble phase and a liquid phase;
(Ii) separating the insoluble phase from the liquid phase;
(Iii) a) adding an acid to the insoluble phase to form a fatty acid, or adding a monohydric alcohol and an acidic catalyst to the insoluble phase to form a fatty acid ester, thereby producing an aqueous phase and an organic phase Or b) first adding an acid to the insoluble phase and then adding a monohydric alcohol and an acidic catalyst to at least a portion of the resulting fatty acid to esterify the fatty acid. The process according to claim 1, wherein the starting material is a monohydric alcohol, a polyhydric alcohol or a mixture thereof as the alcohol. The process according to claim 2, wherein the monohydric alcohol is methanol, ethanol or 1-propanol.   The method according to claim 2 or 3, wherein the polyhydric alcohol is glycerol. The process according to claim 1, wherein the starting material is a fraction produced as a result of a transesterification reaction of lipids.   The method according to claim 1, wherein the metal ion generating agent is calcium chloride or magnesium chloride.     The method of claim 1, wherein the metal ion generating agent is calcium chloride. The method according to claim 1, wherein the metal ion generating agent is added as a solid or a liquid.   The method according to claim 1, wherein the metal ion generating agent is added as a solid. 10. A process according to any preceding claim wherein a metal ion generator is added in an amount that precipitates at least 40 mol% of the soap in the starting material. 10. A process according to any preceding claim wherein a metal ion generator is added in an amount that produces a stoichiometric amount of metal ions relative to the amount of soap in the starting material. The method according to any one of claims 1 to 9, wherein a stoichiometrically excess of 10 mol% of the metal ion generator is added to the amount of soap in the starting material.   The method according to any one of claims 1 to 12, wherein the insoluble phase contains soap. The method according to any one of claims 1 to 13, wherein the liquid phase contains a polyhydric alcohol or a monohydric alcohol or a mixture of several kinds of alcohols. 15. A process according to any preceding claim wherein an acid is added into the insoluble phase to produce a fatty acid or fatty acid mixture. The method according to any one of claims 1 to 14, wherein hydrochloric acid or sulfuric acid is added into the insoluble phase to produce a fatty acid or a fatty acid mixture. A fatty acid ester is produced by adding a monohydric alcohol and an acidic catalyst to the insoluble phase.
16. The method according to any one of 16 to 16. The method according to any one of claims 1 to 16, wherein a monohydric alcohol and hydrochloric acid or sulfuric acid are added to the insoluble phase to produce a fatty acid ester. 17. An acid is first added to an insoluble phase to produce a fatty acid, and then a monohydric alcohol and an acidic catalyst are added to at least a portion of the produced fatty acid to esterify the fatty acid.
The method according to any one. The organic phase comprises a fatty acid ester or a fatty acid ester mixture, a method according to claims 1 to 19 or characterized by the aqueous phase contains water and an inorganic salt. The method according to any one of claims 1 to 20 , wherein the organic phase and the aqueous phase are separated from each other and then collected. Use of a fatty acid, a fatty acid ester or a mixture of a fatty acid and a fatty acid ester produced by the method according to any one of claims 1 to 21 as a feedstock in (i) fatty acid esterification or (ii) lipid hydrotreatment. Use of an alcohol mixture produced in the production of biodiesel fuel, the production of fatty acids, fatty acid esters or mixtures thereof by the process according to any of claims 1 to 21 .

Images