Production of sterols from tall oil pitch

Abstract

A process for treating a stream comprising tall oil pitch (TOP) to produce at least one stream comprising sterols, the process comprising: - performing a hydrolysis step in a reactor to break ester bonds in compounds of the tall oil pitch (TOP) to produce a hydrolyzed tall oil pitch (TOP) stream; - performing a separation step on the hydrolyzed tall oil pitch (TOP) stream after the hydrolysis step as an intermediate treatment before a reactive distillation step to remove part of the water content from the hydrolyzed tall oil pitch (TOP) stream, wherein the separation step is performed at a lower pressure than the hydrolysis step; - performing a reactive distillation step on the hydrolyzed tall oil pitch (TOP) stream in a column after the separation step; and - producing a sterol-rich stream from the column.

Description

Technical Field

[0001] This invention relates to a method and system for producing sterols from tall oil pitch. Furthermore, this invention also relates to a sterol fraction obtainable by the method according to the invention. Summary of the Invention

[0002] This invention relates to a method for processing a stream containing tall oil bitumen (TOP) to produce at least one stream containing sterols, the method comprising:

[0003] - A hydrolysis step is carried out in a reactor to break the ester bonds in the tall oil bitumen (TOP) compound to produce a hydrolyzed tall oil bitumen (TOP) stream;

[0004] - A separation step is performed on the hydrolyzed tall oil pitch (TOP) stream after the hydrolysis step as an intermediate treatment before the reactive distillation step to remove some of the water contents from the hydrolyzed tall oil pitch (TOP) stream, wherein the separation step is carried out at a lower pressure than the hydrolysis step;

[0005] - Following the separation step, a reactive distillation step is performed in the tower on the hydrolyzed tall oil pitch (TOP) stream; and

[0006] - Producing a sterol-rich feed stream from the tower.

[0007] Other hydrolysis methods exist in the field of tall oil bitumen processing. For example, FI118007 discloses a method for separating sterols from tall oil bitumen products, wherein the method includes mixing bitumen with water, homogenizing and hydrolyzing at 150°C to 300°C and increased pressure to retain water in the liquid phase, recovering the homogenized mixture, and separating and recovering the sterols. The method according to the invention differs from the method according to FI118007 at least in that the separation step for removing water is carried out at a lower pressure than the hydrolysis step, which is not the case in the method disclosed in FI118007. Performing the separation step for water removal at a lower pressure relative to the hydrolysis conditions (i) avoids the use of one or more expensive pressurized separators such as FI118007, (ii) avoids problems associated with the formation of stable emulsions, and (iii) provides a water stream (after flash evaporation and condensation) suitable for direct reuse during hydrolysis, whereas the aqueous phase of FI118007 contains a large amount of free fatty acids and rosin acids (3% to 7%) that are soluble in water under these conditions, thus implying that one or more additional separation steps are required before reuse.

[0008] Furthermore, the method of FI118007 does not include a reactive distillation step, as is the case with the method according to the invention. The use of steam distillation in this step is superior to the method disclosed in FI118007 because the presence of steam prevents recombination of the hydrolyzed TOP components and provides additional opportunities for the hydrolysis of any unreacted ester entities into their individual parts (partially, water is present in a large molar excess (steam) relative to any unreacted ester entity, i.e., conditions favorable to hydrolysis). In contrast, the separation according to the method disclosed in FI118007 is carried out at high temperature and low pressure, i.e., under conditions such as high reaction rates and product (water) removal that are actually favorable to esterification reactions (recognition of the hydrolyzed TOP components). Therefore, it can be said that the overall effect of the separation means employed in the method according to the invention is not only efficient separation but also an increased yield of valuable components previously lost as esters between sterols and / or other alcohols and fatty acids. Consistent with the above, the method according to the invention provides an optimization of first removing water and then separating fatty acids during the reactive distillation step. Furthermore, the invention provides a flash distillation step as described above.

[0009] Furthermore, if one is interested in measuring whether the ester bonds have been broken as described above, the saponification value, acid value, and the difference between them before and after the hydrolysis step can be used. This provides the value of the esterification value, i.e., the value of "deesterification" according to the invention.

[0010] Suitablely, the method according to the invention ensures a conversion level of at least 50%, preferably at least 60%, and more preferably at least 70% of the esters contained in the mixture. Detailed Implementation

[0011] The following provides and further discusses some specific embodiments of the invention.

[0012] According to one embodiment, the temperature of the hydrolysis step in the reactor is maintained in the range of 230°C to 290°C, preferably in the range of 260°C to 290°C. This temperature is the optimal temperature to ensure a balance between conversion and degradation.

[0013] As mentioned above, according to the present invention, a separation step is performed on the hydrolyzed tall oil pitch (TOP) stream after the hydrolysis step as an intermediate treatment before the reactive distillation step to remove a portion of the water contents from the hydrolyzed tall oil pitch (TOP) stream. As can be understood from the context, the method according to the present invention involves removing most of the water contents from the tall oil pitch (TOP), while still retaining a small portion of water contents, which prevents the recombination of components containing the original esters. Therefore, according to one embodiment, the separation step is preferably carried out in a flash distillation tower by reducing the pressure of the hydrolyzed tall oil pitch (TOP) stream, more preferably to remove a portion of the water contents from the hydrolyzed tall oil pitch (TOP) stream, such that at least 1% by weight of water is retained in the hydrolyzed tall oil pitch (TOP) stream.

[0014] Furthermore, according to another embodiment, the method further includes a separation step in the column to produce a sterol-rich stream in the lower part relative to the column's inlet feed point and a fuel-compatible stream in the upper part relative to the column's inlet feed point. As an example, the term "fuel-compatible component" can refer to a fatty acid-rich fraction or a fraction substantially containing components with a molecular weight less than 350 g / mol. Furthermore, a fuel-compatible stream can also be considered, taking into account all components in the stream entering the column, as a fraction containing components with a considerably high fuel value.

[0015] Regarding the description of "the lower and upper parts relative to the column inlet feed point," it can be said that the specific design features are typical of those known in the art. For example, design features incorporating "the lower part relative to the column inlet feed point" typically function as features known to promote the evaporation of lighter components and allow them to move upwards, thus ensuring that the bottom stream is rich in heavier components, such as providing a large surface area to reduce diffusion path (more efficient stripping) and energy supply methods. Conversely, design features also known in the art related to "the upper part relative to the column inlet feed point" enable the provision of condensation, reflux, and all other features designed to limit the composition of the fractions leaving the upper part of the column, such as ensuring only a minimum amount of heavy components are present.

[0016] According to one specific embodiment, the reactive distillation step is a steam distillation step. In this case, the use of steam has several functions and / or advantages, such as not only preventing recombination of the components of the hydrolyzed esters, but also increasing the opportunity for additional hydrolysis of unreacted esters. Superheated steam is fed into the column below the so-called stripping section in the lower part relative to the column's inlet feed point. Along the height within this section, components with molecular weights less than 350 g / mol that have traveled upwards within the column are continuously stripped away. Furthermore, the material in this section is at a temperature comparable to that used in the hydrolysis step, and the sterols have been concentrated, and their esters are encountering a large amount of locally excess superheated steam (water), where both conditions (i.e., sufficient temperature and sufficient concentration) promote additional ester hydrolysis. Thus, steam provides efficient separation and transport of fuel-compatible components toward the upper part relative to the column's inlet feed point (where these fuel-compatible components can be collected), and also provides a sterol-rich, and more specifically free sterol-rich, bottom stream at the lower part relative to the column's inlet feed point.

[0017] Furthermore, according to yet another embodiment, the hydrolysis step is a non-catalytic hydrolysis step. This is also what distinguishes the method according to the invention from several known hydrolysis methods.

[0018] Furthermore, according to another embodiment, the sterol-rich stream produced from the lower part of the feed point relative to the tower inlet is further processed by a separation step in one or more of a thin-film evaporator, a short-path evaporator, or a combination of one or more thin-film evaporators and one or more short-path evaporators, preferably in a separation step in at least a short-path evaporator, more preferably in a first separation step in a thin-film evaporator, to remove moisture to produce a sterol-rich dry stream, which is further processed in one or more short-path evaporators.

[0019] Furthermore, according to another embodiment, the sterol-rich stream produced from the lower part of the feed point relative to the tower inlet is further processed at a temperature below 260°C.

[0020] The present invention also provides a system arranged for processing a stream containing tall oil bitumen (TOP) to produce at least one stream containing sterols, the system comprising:

[0021] - Hydrolysis unit;

[0022] - Separation unit; and

[0023] -Reactive distillation column,

[0024] The separation unit is located between the hydrolysis unit and the reactive distillation column and is connected to both the hydrolysis unit and the reactive distillation column.

[0025] According to the present invention, the system includes a hydrolysis unit. This hydrolysis unit is any type of container capable of providing and ensuring the temperature, pressure, and reaction time required for the entire hydrolysis process.

[0026] It should be understood that hydrolysis implies contact between water and the TOP feed stream entering the hydrolysis unit. Furthermore, the greater the contact, the greater the chance of ester bond disruption (hydrolysis). Therefore, effective mixing is provided by any standard processing device to ensure good contact between water and TOP. Typical examples of such processing devices are, but are not limited to, static and / or dynamic mixers, and other physical devices such as baffles, trays, packing, etc. Moreover, the device for providing effective mixing can be located upstream of the hydrolysis unit and / or an integral part of the unit design, thereby maintaining good contact between water and TOP throughout the hydrolysis process.

[0027] According to the present invention, the system includes a separation unit located between and connected to the hydrolysis unit and the reactive distillation column. Furthermore, according to one embodiment, the separation unit is a flash distillation column.

[0028] According to yet another embodiment, the reactive distillation column is a steam distillation column. According to one embodiment, the reactive distillation step is a steam distillation step carried out in a steam distillation column, and wherein at least a portion of the steam distillation column is maintained at a temperature of up to 260°C, preferably, said portion of the steam distillation column maintained at the temperature of up to 260°C is located below the inlet feed point of the steam distillation column.

[0029] Furthermore, according to one embodiment, the system includes at least one post-treatment unit connected to the reactive distillation column, wherein the at least one post-treatment unit is one or more of a thin-film evaporator, a short-path evaporator, or a combination of one or more thin-film evaporators and one or more short-path evaporators. According to one embodiment, the system includes a thin-film evaporator connected to the reactive distillation column for further separation of the sterol-rich stream produced from the lower portion relative to the inlet feed point of the reactive distillation column, and wherein the system includes at least one short-path evaporator for further processing of the sterol-rich stream obtained from the thin-film evaporator; preferably, the system includes at least two short-path evaporators connected in series. To ensure that a truly dry stream enters the short-path evaporator unit, it may be meaningful to first arrange the thin-film evaporator.

[0030] According to one embodiment, the system includes one or more condensers, at least one of which is connected to a reactive distillation column to receive at least a portion of a feed stream rich in fuel-compatible components. The at least one condenser is arranged to recycle the water / steam contents as liquid water to a water tank. Preferably, the at least one condenser is connected to a post-treatment unit to allow the feed stream rich in water / steam contents to flow from the post-treatment unit to the condenser. The at least one condenser is arranged to recycle the water / steam contents as liquid water to a water tank.

[0031] Furthermore, according to one embodiment, the system includes a condenser connected to a separation unit located between a hydrolysis unit and a reactive distillation column, the separation unit preferably being a flash distillation column, which produces a steam stream and a lean-water hydrolyzed TOP stream, the condenser being arranged to recirculate the water / steam contents as liquid water back to a water tank.

[0032] Furthermore, according to another embodiment, the system includes a condenser connected to a reactive distillation column to receive at least a portion of a feed stream rich in fuel-compatible components. The at least one condenser is also connected to a post-treatment unit to allow a feed stream rich in water / steam contents to flow from the post-treatment unit to the condenser. The at least one condenser is also connected to a separation unit located between a hydrolysis unit and the reactive distillation column, preferably a flash distillation column, which produces a steam feed stream and a water-lean hydrolyzed TOP feed stream. The at least one condenser is arranged to recycle the water / steam contents as liquid water back to a water tank.

[0033] It should be understood from the foregoing that the system according to the invention may include one or more condensers. In the case of a single condenser, this condenser is one that is connected to all the units mentioned above that are to be connected to the condenser.

[0034] In addition, according to another embodiment, the system includes a steam generator unit connected to the reactive distillation column for feeding steam into the reactive distillation column.

[0035] According to one specific embodiment, the reactive distillation column includes at least two distinct zones separated by a packing device relative to the column height. An upper zone is arranged to receive a fuel-compatible stream from above the inlet feed point of the reactive distillation column, and a lower zone is arranged to receive a sterol-rich stream from below the inlet feed point of the reactive distillation column. The fuel-compatible stream and the sterol-rich stream are arranged to remain separate from each other. The term "fuel-compatible stream" has already been mentioned above.

[0036] Furthermore, the present invention provides a sterol fraction obtainable from tall oil pitch, the sterol fraction comprising at least 70% by weight of sterols derived from the sum of campesterol, campesteranol, β-sitosterol and sitosterol, preferably, the sterol fraction comprising at least 75% by weight of sterols derived from the sum of campesterol, campesteranol, β-sitosterol and sitosterol.

[0037] According to one embodiment, the sterol fraction can be obtained by the method according to the present invention and as described above.

[0038] According to another embodiment, the level of betulin is up to 1% by weight, preferably up to 0.5% by weight, more preferably up to 0.1% by weight, wherein the level of α-sitosterol is preferably up to 2% by weight, more preferably up to 1% by weight, and most preferably up to 0.5% by weight.

[0039] Furthermore, according to yet another embodiment, the present invention provides a high-purity sterol fraction obtainable from tall oil, the high-purity sterol fraction comprising the sterol fraction further concentrated as provided above, and comprising at least 95% by weight of sterols derived from the sum of campesterol, campesteranol, β-sitosterol and sitosterol.

[0040] Detailed description of the accompanying drawings and embodiments

[0041] Figures 1 to 3 Three different implementation schemes according to the present invention are provided.

[0042] like Figure 1As can be seen, tall oil pitch (TOP) stream (1) is combined with water (2) to provide a combined TOP and water stream (3). This stream 3 is then fed to a hydrolysis reactor (4), from which hydrolyzed tall oil pitch (TOP) stream is produced. This stream is then introduced to a separation step (5), in this case, a flash distillation tower (5). Water (after flashing and condensation) is separated (6) and can be recycled as water to be combined with TOP before hydrolysis. The remaining hydrolyzed tall oil pitch (TOP) stream after separation is then introduced to a reactive steam distillation tower (7). From this step (7), a sterol-rich stream (10), a water stream (condensed steam) (8) (which can be combined with the water recycling stream), and a stream (9) containing fuel-compatible components are produced. The sterol-rich stream (10) is appropriately exposed to one or more post-processing steps (11) including the separation of water (evaporated and condensed (12)) which can be combined with a water recycling loop to produce a crude ligsterol stream (13) and a residual TOP stream (14).

[0043] exist Figure 2 In the middle, it is shown that... Figure 1 The embodiment shown is consistent with one embodiment, however, in this case, the system also includes a water tank (15). This water tank is intended to provide a different form of production alternative in terms of adding water to the production line when the water flow (2) is combined with the TOP flow (1) to provide the one or more combined TOP and water flow (3).

[0044] exist Figure 3 In the middle, it provides with Figure 1 and Figure 2 The embodiment shown is similar to another embodiment of the invention. In this case, a steam generator (20) is used in the system according to the invention to provide superheated steam (30) used in the reactive steam distillation column (7).

[0045] Regarding the above alternatives, the following can be provided as an example. Tall bitumen (TOP) (1) may contain different levels of sterols, and the following should be considered as an example only. In one possible tall bitumen (TOP) stream (1), the sterol content level is in the range of 10% to 12% by weight, with free sterols at most 1.5% by weight. It should be noted here that the total amount of sterols can be higher, depending on the CTO and TOP sources. Water (2) is then added to the CTO to provide a combined TOP and water stream (3). A maximum of up to 30% by weight of water is added relative to TOP (1). It should be noted that generally using lower concentration levels of water, such as from stearoyl ester:water = 1:2 moles to 30% by weight or from stearoyl ester:water = about 1:2 moles to about 30% by weight, should be considered as the maximum value that minimizes the risk of a 2-phase system in the combined TOP and water stream (3).

[0046] The temperature in the hydrolysis reactor (4) is maintained in the range of 230°C to 290°C, preferably in the range of 260°C to 290°C. For this step, it is meaningful to drive the conversion without driving sterol degradation. Temperatures above 290°C may be problematic due to increased degradation. The pressure in the hydrolysis reactor depends on the temperature. At a suitable temperature, the pressure can be approximately 70 to 80 bar.

[0047] The separation step is carried out in a flash tower (5) at a lower pressure than that in the hydrolysis step.

[0048] Water (after flash evaporation and condensation) is separated (6) and can be recycled for use as water to be combined with TOP prior to hydrolysis. The remaining hydrolyzed tall oil pitch (TOP) stream after separation is then introduced into a reactive steam distillation column (7), wherein at least a portion of the distillation column (7), preferably the lower part of the distillation column, is maintained at a temperature of up to 260°C and a negative pressure (vacuum pressure level). From this step (7), a sterol-rich stream (10), a water stream (condensed steam) (8) (which can be combined with the water recirculation stream), and a stream (9) containing fuel-compatible components, said fuel-compatible component stream (9) preferably having a total sterol content of up to 0.1% by weight. The sterol-rich stream (10) (wherein suitably, the sum of components with a molecular weight <350 g / mol is less than 0.5% by weight) is suitably exposed to one or more post-treatment steps (11). One such step is the separation of water (after evaporation and condensation (12)), which can be combined with a water recycling loop. The crude ligsterol stream (13) produced preferably has a total sterol content of at least 60% by weight, more preferably at least 65% by weight, and most preferably at least 70% by weight.

Claims

1. A method for processing a stream containing tall oil bitumen (TOP) to produce at least one stream containing sterols, the method comprising: - A hydrolysis step is carried out in a reactor to break the ester bonds in the compound of the tall oil bitumen (TOP) to produce a hydrolyzed tall oil bitumen (TOP) stream; - Following the hydrolysis step, the hydrolyzed tall oil pitch (TOP) stream is subjected to a separation step as an intermediate treatment prior to the reactive distillation step to remove some of the water contents from the hydrolyzed tall oil pitch (TOP) stream, wherein the separation step is carried out at a lower pressure than the hydrolysis step. - Following the separation step, the hydrolyzed tall oil pitch (TOP) stream is subjected to a reactive distillation step in a tower; and - A sterol-rich feed stream is produced from the tower.

2. The method according to claim 1, wherein the temperature of the hydrolysis step in the reactor is maintained in the range of 230°C to 290°C, preferably in the range of 260°C to 290°C.

3. The method according to claim 1 or 2, wherein the separation step is carried out in a flash tower, preferably by reducing the pressure of the hydrolyzed tall oil bitumen (TOP) stream, more preferably by removing some of the water contents from the hydrolyzed tall oil bitumen (TOP) stream, such that at least 1% by weight of water remains in the hydrolyzed tall oil bitumen (TOP) stream.

4. The method according to any one of claims 1 to 3, wherein the method further comprises a separation step in the tower to produce a sterol-rich stream in the lower part relative to the inlet feed point of the tower and a fuel-compatible stream in the upper part relative to the inlet feed point of the tower.

5. The method according to any one of claims 1 to 4, wherein the reactive distillation step is a steam distillation step.

6. The method according to any one of claims 1 to 5, wherein the reactive distillation step is a steam distillation step performed in a steam distillation column, and wherein at least a portion of the steam distillation column is maintained at a temperature of up to 260°C, preferably, the portion of the steam distillation column maintained at the temperature of up to 260°C is positioned below the inlet feed point of the steam distillation column.

7. The method according to any one of claims 1 to 6, wherein the hydrolysis step is a non-catalytic hydrolysis step.

8. The method according to any one of claims 1 to 7, wherein the sterol-rich stream produced from the lower portion relative to the inlet feed point of the tower is further processed by a separation step in one or more of a thin-film evaporator, a short-path evaporator, or a combination of one or more thin-film evaporators and one or more short-path evaporators, preferably in a separation step in at least a short-path evaporator, more preferably in a first separation step in a thin-film evaporator, to remove moisture to produce a sterol-rich dry stream, which is further processed in one or more short-path evaporators.

9. The method according to any one of claims 1 to 8, wherein the sterol-rich stream produced from the lower portion relative to the inlet feed point of the tower is further processed at a temperature below 260°C.

10. A system arranged for processing a stream containing tall oil bitumen (TOP) to produce at least one stream containing sterols, said system comprising: - Hydrolysis unit; -Separation unit; and -Reactive distillation column, The separation unit is located between the hydrolysis unit and the reactive distillation column and is connected to both the hydrolysis unit and the reactive distillation column.

11. The system of claim 10, wherein the reactive distillation column is a steam distillation column.

12. The system according to any one of claims 10 to 11, wherein the separation unit is a flash tower.

13. The system according to any one of claims 10 to 12, wherein the system comprises at least one post-processing unit connected to the reactive distillation column, wherein the at least one post-processing unit is one or more of a thin-film evaporator, a short-path evaporator, or a combination of one or more thin-film evaporators and one or more short-path evaporators.

14. The system according to any one of claims 10 to 13, wherein the system includes a thin-film evaporator connected to the reactive distillation column for further separation of the sterol-rich stream produced from the lower portion relative to the inlet feed point of the reactive distillation column, and wherein the system includes at least one short-path evaporator for further processing the sterol-rich stream obtained from the thin-film evaporator, preferably, the system includes at least two short-path evaporators connected in series.

15. The system according to any one of claims 10 to 14, wherein the system comprises one or more condensers, at least one condenser being connected to the reactive distillation column to receive at least a portion of a feed stream rich in fuel-compatible components, the at least one condenser being arranged to recycle the water / steam contents as liquid water to a water tank, preferably, the at least one condenser being connected to a post-treatment unit to allow the feed stream rich in water / steam contents to flow from the post-treatment unit to the condenser, the at least one condenser being arranged to recycle the water / steam contents as liquid water to a water tank.

16. The system according to any one of claims 10 to 15, wherein the system includes a condenser connected to a separation unit positioned between the hydrolysis unit and the reactive distillation column, the separation unit preferably being a flash distillation column, the separation unit producing a steam stream and a water-lean hydrolyzed TOP stream, the condenser being arranged to recirculate the water / steam contents as liquid water to a water tank.

17. The system according to any one of claims 10 to 16, wherein the system comprises a condenser connected to the reactive distillation column to receive at least a portion of a feed stream rich in fuel-compatible components, the at least one condenser being further connected to a post-treatment unit to allow a feed stream rich in water / steam contents to flow from the post-treatment unit to the condenser, and the at least one condenser being further connected to a separation unit located between the hydrolysis unit and the reactive distillation column, the separation unit preferably being a flash distillation column, the separation unit producing a steam feed stream and a water-lean hydrolyzed TOP feed stream, the at least one condenser being arranged to recycle the water / steam contents as liquid water to a water tank.

18. The system according to any one of claims 10 to 17, wherein the system includes a steam generator unit connected to the reactive distillation column for feeding steam into the reactive distillation column.

19. The system according to any one of claims 10 to 18, wherein the reactive distillation column comprises at least two distinct zones separated by a packing device relative to the column height, wherein an upper zone is arranged to feed a fuel-compatible stream from above the inlet feed point of the reactive distillation column, and a lower zone is arranged to feed a sterol-rich stream from below the inlet feed point of the reactive distillation column, wherein the fuel-compatible stream and the sterol-rich stream are arranged to remain separate from each other.

20. A sterol fraction obtainable from tall oil pitch, said sterol fraction comprising at least 70% by weight of sterols derived from the sum of campesterol, campesteranol, β-sitosterol and sitosterol, preferably, said sterol fraction comprising at least 75% by weight of sterols derived from the sum of campesterol, campesteranol, β-sitosterol and sitosterol.

21. The sterol fraction according to claim 20, wherein the sterol fraction can be obtained by the method according to any one of claims 1 to 9.

22. The sterol fraction according to claim 20 or 21, wherein the level of betulin is up to 1 wt%, preferably up to 0.5 wt%, more preferably up to 0.1 wt%, wherein the level of α-sitosterol is up to 2 wt%, more preferably up to 1 wt%, and most preferably up to 0.5 wt%.

23. A high-purity sterol fraction obtainable from tall oil, said high-purity sterol fraction comprising a further concentrated sterol fraction according to any one of claims 20 to 22, and at least 95% by weight of sterols derived from the sum of campesterol, campesteranol, β-sitosterol and sitosterol.

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