CA2349780C - Improved method for the production of sterols from tall oil - Google Patents
Improved method for the production of sterols from tall oil Download PDFInfo
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- CA2349780C CA2349780C CA 2349780 CA2349780A CA2349780C CA 2349780 C CA2349780 C CA 2349780C CA 2349780 CA2349780 CA 2349780 CA 2349780 A CA2349780 A CA 2349780A CA 2349780 C CA2349780 C CA 2349780C
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- sterols
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Abstract
A method for the preparation of sterols from crude tall oil comprising the steps of distilling the crude tall oil to yield a residue, re-distilling the residue in a second distillation stage to yield a distillate, and precipitating the sterol-enriched distillate to yield sterols.
Description
Application No. 2,349,780 3 BACKGROUND OF THE INVENTION
1. Field of Invention This invention relates to the isolation of sterols from tall oil.
1. Field of Invention This invention relates to the isolation of sterols from tall oil.
2. Related Art Sterols, in particular phytosterols, have been identified recently as the source material for the preparation of anti-cholesterolemic agents for humans. It is generally recognized in the literature that tall oil, a by-product of the kraft pulping of coniferous wood, contains sterols in the range of 2 to 10% by weight. More particularly, sterols constitute a major part of the unsaponifiable fraction of tall oil.
During the past 50 years, numerous methods have been reported for the isolation of sterols from tall oil. Most of these methods involved solvent extraction of soap, the precursor of tall oil, with a variety of organic solvents. In US Patent 5,770,749, Kutney et al., teaches the use of a mixture of ketones, hydrocarbons and water to extract sterols from soap. The efficiency of sterol extraction and complexity of recovering the multi-component spent solvent are very problematic.
The recovery of sterols from tall oil pitch, a residue of the distillation of tall oil has also been described. In US Patent 2,715,638, Albrecht et al. teaches the use of metal hydroxide to separate fatty acid esters from steryl esters, converting the separated steryl esters to free sterols by means of refluxing in an alkali-alcohol medium, and finally by precipitation to yield sterols. Harada et al.
teaches in US Patent 3,887,537 the use of low-vaccum thin-film evaporation of saponified tall oil pitch or tall oil head to recover fatty acids and rosin acids. In US Patent 3,926,936, Lehtinen teaches the saponification of tall oil pitch, followed by acidification of the saponified tall oil pitch prior to distillation to yield an unsaponifiable-enriched fraction. This fraction is implied to contain most of the sterols present in the original tall oil pitch. In laid-open International Patent Application WO 99/4247 1, Wong et al. teaches the alkaline saponification and subsequent neutralization of tall oil pitch prior to the distillation for the isolation of a sterol-enriched distillate. This method would create an involuntary stream of toxic waste water which must be treated prior to discharge to the receiving waters. Moreover, the cost of chemicals for saponification and neutralization of tall oil pitch in the preparatory steps is not insignificant.
Hughes teaches in US Patent 4,524,024 the use of water hydrolysis to enhance the partition of sterols as steryl esters into the pitch fraction for the subsequent distillation of neat tall oil. Sterols would be recovered from the tall oil pitch by means of precipitation in a mixture of organic solvents and water, in accordance with the teaching of Julian as described in US Patent 3,691,211.
In US Patent 4,849,112, Barder et al. teaches the use of carbon absorbents to separate sterols from tall oil pitch. Pitch is first made by the distillation of tall oil.
Application No. 2,349,780 4 SUMMARY OF THE INVENTION
The present invention affords a direct means to provide a sterol-enriched fraction which can yield sterols upon subsequent precipitation in a water-organic solvent mixture. The preferred embodiment of the present invention as given in Figure 1 comprises the following steps:
a) Tall oil [ 1] is fed into a degasser [2] to remove volatile components such as monoterpenoids [3], b) The stripped tall oil [4] is distilled at 200 to 300 degrees Celsius and at 0.01 millibar to 10 millibar pressure in a short-path distillation unit [5], to yield a distillate [6] and a residue [7].
Distillate [6] is tall oil with an elevated Acid Number, which is an article of commerce.
c) The residue [7] is distilled immediately in a second short-path distillation unit [8] operating at 200 to 300 degrees Celsius and at 0.001 millibar to 0.05 millibar pressure, to yield a second residue [9] and a second distillate [10]. The second residue [9] may be used as a power-boiler fuel or as a softening agent for recycled asphalt in the road paving industry.
d) The second distillate [ 10] is dissolved in a pre-set mixture of water [ 11 ] and organic solvent [ 12]
in a mixing-settling tank [13] at 60 to 100 degrees Celsius. This operating may be performed under pressurized conditions at higher temperatures which would provide the use of a smaller amount of water-solvent mixture.
e) Crude sterols are precipitated in the mixing-settling tank [13] upon cooling the solution to below 30 degrees Celsius, under atmospheric operating conditions f) The crude sterols [ 14] are further purified by washing through centrifuge [ 15] using a fresh mixture of water [ 11 ] and organic solvent [ 12] as the washing liquid. The wash filtrate [ 16] may be recycled within the process prior to conventional recovery of the spent water-solvent.
g) Purified sterol cake [ 17] is dried by known means such as conventional heating with a stream of hot inert gases.
EXAMPLES
The following example illustrates the preferred embodiment of the invention, without limiting the broad scope of application:
Example 1 A sample of commercial tall oil with Acid Number of 102, free sterol content of 57 mg per gram, and esterified sterol content (calculated as free sterols) of 69 mg per gram, was first heated at 100 degrees Celsius for 10 minutes to remove the volatiles. The stripped tall oil is next fed into a short-path distillation apparatus (Model KDL-5 manufactured by UIC GmbH, Alzenau-Horstein, Application No. 2,349,780 5 Germany) by means of a gear pump at the rate of about 399 grams per hour. The apparatus is equipped with liquid nitrogen cold trap to condense any volatiles pulled off by the high vacuum pump.
The operating condition of this first distillation stage was 220 degrees Celsius and 1.3 millibar pressure. The products from this first stage of distillation were:
Free Sterols Esterified Sterols Test L-2558 % Cut m am mg/gram Distillate 67.8 26 2 Residue 29.6 120 42 Cold trap liquid 2.6 nil nil The first-stage residue is the feed material for the second stage short-path distillation tests using the same Model KDL-5 short-path distillation apparatus. The results of the second-stage distillation were as follows:
Test Test Test Distillation temp., deg. C 200 220 240 Pressure, millibars 0.01 0.01 0.01 Feed rate, grams er hour 396 410 413 Distillate % cut by wt. based on feed 35.5 45.6 54.9 to second distillation stage Free sterols, mg per gram 216 236 210 Esterified sterols, mg per gram 8 0 7 % by wt. free sterols recovered, based on 39.8 55.9 59.9 feed to first stage distillation Residue % cut by wt. based on feed 64.5 54.4 45.1 to second distillation stage Free sterols, mg per gram 42 14 6 Esterified sterols, mg per gram 62 65 73 % by wt. free sterols lost, based on feed to 14.1 4.0 1.4 first stage distillation Sterols were recovered from each these second-stage distillates by dissolution, for example, in a mixture of 10% (by weight) water and 90% (by weight) ethanol at 65 degrees Celsius, following the teachings of Julian in U.S. Patent 3,691,211.
During the past 50 years, numerous methods have been reported for the isolation of sterols from tall oil. Most of these methods involved solvent extraction of soap, the precursor of tall oil, with a variety of organic solvents. In US Patent 5,770,749, Kutney et al., teaches the use of a mixture of ketones, hydrocarbons and water to extract sterols from soap. The efficiency of sterol extraction and complexity of recovering the multi-component spent solvent are very problematic.
The recovery of sterols from tall oil pitch, a residue of the distillation of tall oil has also been described. In US Patent 2,715,638, Albrecht et al. teaches the use of metal hydroxide to separate fatty acid esters from steryl esters, converting the separated steryl esters to free sterols by means of refluxing in an alkali-alcohol medium, and finally by precipitation to yield sterols. Harada et al.
teaches in US Patent 3,887,537 the use of low-vaccum thin-film evaporation of saponified tall oil pitch or tall oil head to recover fatty acids and rosin acids. In US Patent 3,926,936, Lehtinen teaches the saponification of tall oil pitch, followed by acidification of the saponified tall oil pitch prior to distillation to yield an unsaponifiable-enriched fraction. This fraction is implied to contain most of the sterols present in the original tall oil pitch. In laid-open International Patent Application WO 99/4247 1, Wong et al. teaches the alkaline saponification and subsequent neutralization of tall oil pitch prior to the distillation for the isolation of a sterol-enriched distillate. This method would create an involuntary stream of toxic waste water which must be treated prior to discharge to the receiving waters. Moreover, the cost of chemicals for saponification and neutralization of tall oil pitch in the preparatory steps is not insignificant.
Hughes teaches in US Patent 4,524,024 the use of water hydrolysis to enhance the partition of sterols as steryl esters into the pitch fraction for the subsequent distillation of neat tall oil. Sterols would be recovered from the tall oil pitch by means of precipitation in a mixture of organic solvents and water, in accordance with the teaching of Julian as described in US Patent 3,691,211.
In US Patent 4,849,112, Barder et al. teaches the use of carbon absorbents to separate sterols from tall oil pitch. Pitch is first made by the distillation of tall oil.
Application No. 2,349,780 4 SUMMARY OF THE INVENTION
The present invention affords a direct means to provide a sterol-enriched fraction which can yield sterols upon subsequent precipitation in a water-organic solvent mixture. The preferred embodiment of the present invention as given in Figure 1 comprises the following steps:
a) Tall oil [ 1] is fed into a degasser [2] to remove volatile components such as monoterpenoids [3], b) The stripped tall oil [4] is distilled at 200 to 300 degrees Celsius and at 0.01 millibar to 10 millibar pressure in a short-path distillation unit [5], to yield a distillate [6] and a residue [7].
Distillate [6] is tall oil with an elevated Acid Number, which is an article of commerce.
c) The residue [7] is distilled immediately in a second short-path distillation unit [8] operating at 200 to 300 degrees Celsius and at 0.001 millibar to 0.05 millibar pressure, to yield a second residue [9] and a second distillate [10]. The second residue [9] may be used as a power-boiler fuel or as a softening agent for recycled asphalt in the road paving industry.
d) The second distillate [ 10] is dissolved in a pre-set mixture of water [ 11 ] and organic solvent [ 12]
in a mixing-settling tank [13] at 60 to 100 degrees Celsius. This operating may be performed under pressurized conditions at higher temperatures which would provide the use of a smaller amount of water-solvent mixture.
e) Crude sterols are precipitated in the mixing-settling tank [13] upon cooling the solution to below 30 degrees Celsius, under atmospheric operating conditions f) The crude sterols [ 14] are further purified by washing through centrifuge [ 15] using a fresh mixture of water [ 11 ] and organic solvent [ 12] as the washing liquid. The wash filtrate [ 16] may be recycled within the process prior to conventional recovery of the spent water-solvent.
g) Purified sterol cake [ 17] is dried by known means such as conventional heating with a stream of hot inert gases.
EXAMPLES
The following example illustrates the preferred embodiment of the invention, without limiting the broad scope of application:
Example 1 A sample of commercial tall oil with Acid Number of 102, free sterol content of 57 mg per gram, and esterified sterol content (calculated as free sterols) of 69 mg per gram, was first heated at 100 degrees Celsius for 10 minutes to remove the volatiles. The stripped tall oil is next fed into a short-path distillation apparatus (Model KDL-5 manufactured by UIC GmbH, Alzenau-Horstein, Application No. 2,349,780 5 Germany) by means of a gear pump at the rate of about 399 grams per hour. The apparatus is equipped with liquid nitrogen cold trap to condense any volatiles pulled off by the high vacuum pump.
The operating condition of this first distillation stage was 220 degrees Celsius and 1.3 millibar pressure. The products from this first stage of distillation were:
Free Sterols Esterified Sterols Test L-2558 % Cut m am mg/gram Distillate 67.8 26 2 Residue 29.6 120 42 Cold trap liquid 2.6 nil nil The first-stage residue is the feed material for the second stage short-path distillation tests using the same Model KDL-5 short-path distillation apparatus. The results of the second-stage distillation were as follows:
Test Test Test Distillation temp., deg. C 200 220 240 Pressure, millibars 0.01 0.01 0.01 Feed rate, grams er hour 396 410 413 Distillate % cut by wt. based on feed 35.5 45.6 54.9 to second distillation stage Free sterols, mg per gram 216 236 210 Esterified sterols, mg per gram 8 0 7 % by wt. free sterols recovered, based on 39.8 55.9 59.9 feed to first stage distillation Residue % cut by wt. based on feed 64.5 54.4 45.1 to second distillation stage Free sterols, mg per gram 42 14 6 Esterified sterols, mg per gram 62 65 73 % by wt. free sterols lost, based on feed to 14.1 4.0 1.4 first stage distillation Sterols were recovered from each these second-stage distillates by dissolution, for example, in a mixture of 10% (by weight) water and 90% (by weight) ethanol at 65 degrees Celsius, following the teachings of Julian in U.S. Patent 3,691,211.
Claims (10)
1. A process for the preparation of sterols from tall oil comprising the steps of:
a) stripping of volatiles from tall oil, b) distilling stripped tall oil under elevated temperature and reduced pressure conditions, c) distilling the residue from the preceding step under elevated temperature and reduced pressure to yield a sterol-enriched distillate, d) dissolving said second distillate in a mixture of water and organic solvent or a mixture of organic solvents only to precipitate sterol, and e) cooling the solution to precipitate sterols.
a) stripping of volatiles from tall oil, b) distilling stripped tall oil under elevated temperature and reduced pressure conditions, c) distilling the residue from the preceding step under elevated temperature and reduced pressure to yield a sterol-enriched distillate, d) dissolving said second distillate in a mixture of water and organic solvent or a mixture of organic solvents only to precipitate sterol, and e) cooling the solution to precipitate sterols.
2. A process according to claim 1 in which the stripping of tall oil is made under moderate temperature and slightly reduced pressure conditions.
3. A process according to claim 1 in which the first distillation stage is conducted at 200 to 300 degrees Celsius and 0.1 to 10 millibar pressure.
4. A process according to claim 1 in which the second stage distillation of the first-stage residue is made at 200 to 300 degrees Celsius and 0.00 1 to 0.1 millibar pressure.
5. A process according to claim 1 in which dissolution of the second-stage distillate is made in a solvent selected from the group consisting of an alkane, ketone, acetate, ether, alcohol, and mixtures thereof.
6. A process according to claim 1 in which dissolution of the second-stage distillate is made in a solvent comprising water and a monohydric alcohol.
7. A process according to claim 1 in which dissolution of the second-stage distillate is made at above about 60 degrees Celsius.
8. A process according to claim 1 in which the solution is cooled to below about 30 degrees Celsius to precipitate the sterols.
9. A process according to claim 1, further comprising step of rewashing the precipitated sterols with a mixture of water and organic solvents, or with a mixture of organic solvents.
10. A process according to claim 1, further comprising drying the washed sterols.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US58804200A | 2000-06-05 | 2000-06-05 | |
| US09/588,042 | 2000-06-05 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2349780A1 CA2349780A1 (en) | 2001-12-05 |
| CA2349780C true CA2349780C (en) | 2009-03-03 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2349780 Expired - Lifetime CA2349780C (en) | 2000-06-05 | 2001-06-04 | Improved method for the production of sterols from tall oil |
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| Country | Link |
|---|---|
| CA (1) | CA2349780C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9221869B2 (en) | 2008-03-10 | 2015-12-29 | Sunpine Ab | Recovery of phytosterols from residual vegetable oil streams |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI20106252A0 (en) | 2010-11-26 | 2010-11-26 | Upm Kymmene Corp | Method and system for making fuel components |
-
2001
- 2001-06-04 CA CA 2349780 patent/CA2349780C/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9221869B2 (en) | 2008-03-10 | 2015-12-29 | Sunpine Ab | Recovery of phytosterols from residual vegetable oil streams |
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| Publication number | Publication date |
|---|---|
| CA2349780A1 (en) | 2001-12-05 |
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| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |
Effective date: 20210604 |