METHOD FOR THE PROCUREMENT OF FREE UNSATUATED FAT AND / OR FAT ESTERS

Description

[0001] The invention relates to a process for obtaining polyunsaturated free fatty acids and / or fatty acid esters, in which, for the separation of a liquid mixture containing the polyunsaturated fatty acids and / or fatty acid esters, a rising vapor of the liquid mixture in a column of a distillation apparatus having at least 10 theoretical separation stages is brought into contact with descending condensate formed from the vapor, wherein mass and / or heat exchange takes place on internals of the column between the vapor and the condensate.

[0002] US 2011 / 0091947 A1 describes such a process for omega-3 fatty acids, comprising the following steps: a) production of a fatty acid ethyl ester (FAEE) by ethanol lysis of a natural oil or fat using ethanol in the presence of an enzyme catalyst; b) predistillation of the produced fatty acid ethyl ester using a short-path distillation apparatus; c) formation of a concentrated fatty acid by fractional distillation at reduced pressure of the ethyl ester that has undergone predistillation; and d) purification of the concentrated fatty acid by simulated moving bed (SMB) column chromatography.

[0003] US Patent 2010 / 0166620 A1 discloses a process for the continuous production of fatty acid methyl esters from fatty acid triglycerides from waste oil via transesterification using a reusable sugar-based catalyst. The pressure drop between the top and bottom of a column in a distillation apparatus used in this process is 150 mbar.

[0004] In other known processes, due to the high temperature sensitivity of free fatty acids or fatty acid esters, a short-path distillation, which achieves only a relatively low separation efficiency, was typically used. In this process, a thin film of liquid mixture, formed (possibly by wiping) on ​​a heated evaporator surface, is partially evaporated onto a nearby condenser of a short-path distillation apparatus. The geometric arrangement of the evaporator surface and the condenser surface, as well as the short distance between them, allows for operating pressures in the fine vacuum range (1 mbar - 10⁻³ < mbar) and thus correspondingly low evaporation temperatures (see Frank / Kutsche, "Die sanftende Destillation" from the book series "Verfahrenstechnik", Otto Krausskopf Verlag GmbH, Mainz, 1969).

[0005] It is also known through use to employ a distillation apparatus comprising a thin-film evaporator, a rectification column, and a condenser for carrying out a known process for obtaining free fatty acids and / or fatty acid esters. However, processing the liquid mixtures containing fatty acids or fatty acid esters has thus far been considered problematic due to the high temperature sensitivity of these substances.

[0006] The invention is based on the objective of increasing the efficiency of the aforementioned method.

[0007] According to the invention, this problem is solved by carrying out the separation with a pressure drop between the head and the bottom of the column Δp, which is ≥ 3.3 mbar and ≤ 6 mbar.

[0008] Surprisingly, it has been shown that, despite the high temperatures in the distillation apparatus required for the relatively large pressure drop, no decomposition or isomerization of the fatty acid or fatty acid esters occurs when carrying out the process according to the invention. Advantageously, the process achieves a higher throughput with good separation efficiency compared to known processes.

[0009] The process according to the invention is particularly suitable for processing polyunsaturated fatty acids such as omega-6 or omega-3 fatty acids, for example ALA (9Z,12Z,15Z)-octadeca-9,12,15-trienoic acid, SDA (6Z,9Z,12Z,15Z)-octadeca-6,9,12,15-tetraenoic acid, ETA (8Z,11Z,14Z,17Z)-eicosa-8,11,14,17-tetraenoic acid, EPA (5Z,8Z,11Z,14Z,17Z)-eicosa-5,8,11,14,17-pentaenoic acid, HPA (6Z,9Z,12Z,15Z,18Z)-heneicosa-6,9,12,15,18-pentaenoic acid, DPA (7Z,10Z,13Z,16Z,19Z)-docosa-7,10,13,16,19-pentaenoic acid, DHA (4Z,7Z,10Z,13Z,16Z,19Z)-docosa-4,7,10,13,16,19-hexaenoic acid. Such liquid mixtures are conveniently prepared from vegetable oil and / or fish oil and / or from microorganisms, e.g., microalgae, yeast, or bacteria.

[0010] In a preferred embodiment of the invention, the column has at least 30, preferably at least 40, theoretical separation stages.

[0011] In one embodiment of the invention, the separation is carried out with a pressure loss Δp of 3.5 mbar ≤ Δp.

[0012] Advantageously, the F-factor of the column is at most 2 Pa ½< , preferably at most 1.5 Pa ½< , particularly preferably at most 1.1 Pa ½< .

[0013] In one embodiment of the invention, the distillation apparatus used to carry out the process according to the invention comprises a thin-film evaporator. The aforementioned internal components expediently include trays, preferably perforated trays, bubble-cap trays, or valve trays, or packings and / or packings made of sheet metal or wire mesh. A condenser of the distillation apparatus is expediently formed by a total capacitor.

[0014] In a further development of the invention, a bottom product obtained by separation using the described method in the sump of the distillation apparatus is subjected to urea precipitation. In this urea precipitation process, known from the prior art, a mixture of ethanol and urea is brought to a boil, and the bottom product is added while stirring. After cooling, the precipitated urea slurry is separated by filtration. The ethanol contained in the remaining mixture is distilled off and can optionally be used for further precipitations. The remaining mixture is then subjected to a short-path distillation, also known from the prior art.

[0015] In one embodiment of the invention, a head product obtained by separation in the head of the distillation apparatus is processed again using the method described above, and a second bottom product obtained in this way is mixed with a second head product obtained by short-path distillation.

[0016] The liquid mixture can be advantageously enriched by urea precipitation, short-path distillation, and subsequent separation of the overhead product with the free fatty acid or fatty acid ester. For example, highly enriched omega-3 fatty acids can be produced using EPA or DPA.

[0017] The invention is explained in more detail below with reference to exemplary embodiments and the accompanying drawing.

[0018] To perform a rectification, a [unclear text] was used in Fig. 1A schematically depicted distillation apparatus was used, comprising a thin-film evaporator 2 equipped with a motor 15, a rectification column 1 connected to the thin-film evaporator 2 and packed with wire mesh 4,5, and a condenser 3. The rectification column 1 had an F-factor of 1 Pa ½<

[0019] A line 8 is provided between a tray of the rectification column 1 and the thin-film evaporator 2, through which the bottoms are fed to the thin-film evaporator 2. Vapors generated in the thin-film evaporator 2 pass into the rectification column 1 via a vapor tube 9, which connects the thin-film evaporator 2 to the rectification column 1, with the vapor temperature above the column bottom being 180 to 210 °C. A portion that remains unvaporized is discharged from the thin-film evaporator 2 as bottoms product 12. The wire mesh packing 5 (Montz, Hilden) is located in the lower part of the rectification column 1 and acts as a stripping section. The wire mesh packing 4 (Montz, Hilden) is located in the upper part of the column and acts as a reinforcing section.A feed material is introduced into the rectification column 1 via a feed line 10, which opens between the wire mesh packings 4, 5, and is distributed evenly on the wire mesh packing 5 by means of a distribution device 6. A condenser 3 is located at the top of the rectification column 1, by means of which the vapors exiting the column 1 are condensed. A portion of the resulting condensate is returned to the column via a reflux line 14 and distributed evenly on the wire mesh packing 4 by means of another distribution device 7. Any condensate not returned is discharged as distillate from the distillation apparatus via a discharge line 13. A vacuum line 11 leads to a multi-stage vacuum pumping station, which can generate pressures of up to approximately 0.1 mbar in the top of the fractionation column 1.

[0020] The distillation apparatus can operate at throughputs of approximately 100 to 600 kg / h. The experiments described below were conducted at a throughput of 400 kg / h.

[0021] In the results presented below, EE stands for ethyl ester. Example 1:

[0022] The liquid mixture to be processed was a feed oil containing 310 mg / g EPA-EE and 200 mg / g DHA-EE before distillation.

[0023] After distillation with the described distillation apparatus at a pressure difference between the bottom and top of the distillation apparatus of Δp = 3.9 mbar, with a number of approximately 50 theoretical plates and a throughput of 400 kg / h, 73% bottom product and 27% top product were obtained, wherein the bottom product contained 370 mg / g EPA-EE and 270 mg / g DHA-EE and the top product 150 mg EPA-EE and 1.5 mg / g DHA-EE. Example 2:

[0024] The liquid mixture to be processed was a feed oil containing 360 mg / g EPA-EE and 235 mg / g DHA-EE before distillation. After distillation with the described distillation apparatus at a pressure difference between the bottom and top of the apparatus Δp = 3.4 mbar, approximately 50 theoretical plates were used, and a feed rate of 400 kg / h yielded 76% bottom product and 24% top product. The bottom product contained 390 mg / g EPA-EE and 310 mg / g DHA-EE, while the HPE top product contained 255 mg EPA-EE and 1 mg / g DHA-EE. Example 3:

[0025] The liquid mixture to be processed was a feed oil containing 420 mg / g EPA-EE and 210 mg / g DHA-EE before distillation. After distillation with the described distillation apparatus at a pressure difference between the bottom and top of the apparatus of Δp = 3.6 mbar, approximately 50 theoretical plates were used, and a feed rate of 400 kg / h yielded 74% bottom product and 26% top product. The bottom product contained 430 mg / g EPA-EE and 280 mg / g DHA-EE, while the top product contained 400 mg EPA-EE and 15 mg / g DHA-EE. Example 4:

[0026] The liquid mixture to be processed was a feed oil containing 430 mg / g EPA-EE and 145 mg / g DHA-EE before distillation. After distillation with the described distillation apparatus at a pressure difference between the bottom and top of the apparatus Δp = 4.1 mbar, approximately 50 theoretical plates were used, and a feed rate of 400 kg / h yielded 70% bottom product and 30% top product. The bottom product contained 510 mg / g EPA-EE and 205 mg / g DHA-EE, while the top product contained 230 mg / g EPA-EE and 2 mg / g DHA-EE. Example 5:

[0027] The liquid mixture to be processed was a feed oil containing 310 mg / g EPA-EE and 200 mg / g DHA-EE before distillation.

[0028] After distillation with the described distillation apparatus at a pressure difference between the bottom and the top of the distillation apparatus Δp = 3.9 mbar, with a number of 50 theoretical trays and a throughput of 400 kg / h, 73% first bottom product and 27% first top product were obtained, wherein the first bottom product contained 370 mg / g EPA-EE and 270 mg / g DHA-EE and the first top product 150 mg EPA-EE and 1.5 mg / g DHA-EE.

[0029] The first bottoms product was subsequently subjected to urea precipitation. First, a mixture of three parts ethanol and one part urea was brought to a boil, and then the first bottoms product was added while stirring. After cooling this mixture, a urea cake that had precipitated from the mixture was separated by filtration, and the ethanol was distilled off from the remaining mixture. The remaining mixture was then subjected to short-path distillation at a feed rate of 200 kg / h, an evaporator jacket temperature of 180 to 205 degrees Celsius, and a pressure of 0.01 to 0.1 mbar. The second-head product obtained by short-path distillation contained 490 mg / g EPA-EE and 310 mg / g DHA-EE.

[0030] The first-head product was redistilled using a distillation apparatus according to the invention. The resulting second bottom product contained a fatty acid ethyl ester mixture with 610 mg / g EPA-EE and 6 mg / g DHA-EE.

[0031] By mixing the second bottom product and the second top product in a 40:60 ratio, a fatty acid ethyl ester mixture containing 538 mg / g EPA-EE and 188 mg / g DHA-EE was obtained as an intermediate. This mixture was saponified by mixing it with 96% ethanol and 0.617 kg NaOH and heating it to 60°C. After one hour, the mixture was cooled to room temperature and adjusted to a pH of 5 with dilute sulfuric acid. The aqueous and oil phases were separated, and the oil phase was washed. The oil phase was then distilled under vacuum to reduce the water content to less than 0.1%.

[0032] This allowed a product with the composition EPA 538 mg / g and DHA 188 mg / g in the form of free fatty acids to be obtained by subsequent acidification. Example 6:

[0033] The liquid mixture to be processed was a feed oil containing 320 mg / g EPA-EE and 200 mg / g DHA-EE before distillation. After distillation with the described distillation apparatus at a pressure difference between the bottom and top of the distillation apparatus of Δp = 3.5 mbar, approximately 50 theoretical plates were used, and a feed rate of 400 kg / h yielded 74% bottom product and 26% top product. The bottom product contained 370 mg / g EPA-EE and 270 mg / g DHA-EE, while the HPE top product contained 190 mg EPA-EE and 1 mg / g DHA-EE.

[0034] The first bottom product was subsequently subjected to urea precipitation as described above, followed by short-path distillation. The second-head product obtained by short-path distillation contained 490 mg / g EPA-EE and 310 mg / g DHA-EE.

[0035] The first-head product was redistilled using a distillation apparatus according to the invention. The resulting second bottom product contained a fatty acid ethyl ester mixture with 630 mg / g EPA-EE and 3 mg / g DHA-EE.

[0036] By mixing the second bottom product and the second head product in a ratio of 40:60, a fatty acid ethyl ester mixture with 546 mg / g EPA-EE and 187 mg / g DHA-EE was subsequently obtained as the final product.

Claims

1. Process for obtaining polyunsaturated free fatty acid and / or fatty acid ester, wherein in order to separate a liquid mixture containing the polyunsaturated fatty acid and / or the fatty acid ester, ascending vapor of the liquid mixture is brought into contact in a column of a distillation apparatus having at least 10 theoretical plates with downflowing condensate formed from the vapor, with mass transfer and heat transfer taking place between the vapor and the condensate on internals of the column, characterized in that the separation is carried out at a pressure drop between top and bottom of the column Δp which is ≥ 3.3 mbar and ≤ 6 mbar.

2. Process according to Claim 1, characterized in that the liquid mixture contains omega-6 or omega-3 fatty acid and / or alkyl and / or glyceryl monoesters.

3. Process according to Claim 1 or 2, characterized in that the liquid mixture is produced from vegetable oil and / or from fish oil and / or from microorganisms.

4. Process according to Claim 1 or 3, characterized in that the column has at least 30, preferably at least 40, theoretical plates.

5. Process according to any one of Claims 1 to 4, characterized in that the separation is carried out at a pressure drop Δp of ≥ 3.5 mbar.

6. Process according to any one of Claims 1 to 5, characterized in that the F factor of the column is not more than 2 Pa½, preferably not more than 1.5 Pa½, particularly preferably not more than 1.1 Pa½.

7. Process according to any one of Claims 1 to 6, characterized in that the liquid mixture is vaporized by means of a thin film evaporator of the distillation apparatus.

8. Process according to any one of Claims 1 to 7, characterized in that a bottom product obtained at the bottom of the distillation apparatus as a result of the separation is subjected to a urea precipitation and subsequently a short path distillation.

9. Process according to Claim 8, characterized in that an overhead product obtained at the top of the distillation apparatus as a result of the separation is again processed using the process according to any of Claims 1 to 8 and a second bottom product obtained in this way is mixed with a second overhead product obtained by means of the short path distillation.