Multi-stage segmented rectification process for anise oil

Abstract

The invention discloses a multistage segmented rectification process for anise oil, which comprises the following steps: by taking crude anise oil as a raw material, carrying out multistage segmented rectification on a first-stage tower section, a middle tower section and a last-stage tower section through a rectification tower; wherein the first-stage tower section is used for removing light components, the last-stage tower section is used for refining trans-anethole, and the middle tower section is used for gradually increasing the concentration of the target component trans-anethole by gradually increasing the temperature; regular packing is adopted in the middle tower section, and the used packing is catalytic isomerization packing. The multi-stage segmented rectification process for the anise oil can be used for preparing high-purity and high-yield trans-anethole, and is short in process time, low in energy consumption and suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The application relates to a multi-stage segment distillation process of aniseed oil and belongs to the technical field of natural perfume processing. BACKGROUND

[0002] Aniseed oil is mainly divided into two types of star anise oil (aniseed oil) and fennel oil, and is widely used in the fields of food, cosmetics and anti-medicine synthesis as a natural perfume and a medicine intermediate. The core component of aniseed oil is trans-anethole. In addition to trans-anethole, star anise oil also contains eugenol, cumin aldehyde, cedrene and the like, and fennel oil also contains fenchone, estragole, anise aldehyde, phellandrene and the like. Due to the complexity of the components of aniseed oil, the purity of trans-anethole in the aniseed oil is less than 95% through the traditional distillation process, the product purity is insufficient, and the content of cis-anethole impurities exceeds the standard (>0.2%), which cannot meet the demand of the high-end market. Moreover, in order to improve the purity of trans-anethole, the traditional distillation method needs to be distilled for multiple times, but repeated heating will cause heat-sensitive loss, resulting in a low yield, generally not more than 85%. The existing purification technology also combines vacuum distillation with frozen crystallization, such as patent CN201110195675.2. Although the purity of trans-anethole is improved to 99.7%, the total yield is still less than 75%, which is still low, and the freezing time and distillation time are relatively long, the energy consumption is higher, and the technology is not suitable for industrial production. In addition, for the high-end cosmetic market, long-time high-temperature distillation is not good for the aroma of the perfume raw material. SUMMARY

[0003] At least in view of the above-mentioned problems existing in the prior art, the application provides a multi-stage segment distillation process of aniseed oil, which can prepare high-purity and high-yield trans-anethole, and has short process time, low energy consumption and is suitable for industrial production.

[0004] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme: a multi-stage segment distillation process of aniseed oil, which takes crude aniseed oil as raw material and carries out multi-stage segment distillation through a first-stage tower segment, an intermediate tower segment and a last-stage tower segment in a distillation tower. Among them, the light components are removed in the first-stage tower segment, trans-anethole is refined in the last-stage tower segment, and the target component trans-anethole is gradually concentrated in the intermediate tower segment through gradual temperature rise. And the regular packing is used in the intermediate tower segment, and the packing used is catalytic isomerization packing.

[0005] Preferably, the temperature of the tower kettle gradually increases, the pressure in the tower gradually decreases and the reflux ratio gradually increases from the first-stage tower segment, the intermediate tower segment and the last-stage tower segment.

[0006] Preferably, the temperature of the tower kettle is controlled at 75-80 DEG C, the pressure in the tower is controlled at 0.02-0.03 MPa and the reflux ratio is controlled at 2-3:1 in the first-stage tower segment.

[0007] Preferably, the kettle temperature of the intermediate column section is controlled at 80-90℃ and the column pressure is controlled at -0.03-0.02MPa; wherein the intermediate column section is set as three-stage column section, and the temperature is gradually increased, the pressure is gradually reduced, and the reflux ratio is gradually increased.

[0008] Preferably, in the intermediate column section, the temperature is increased by 2-5℃ per stage, the pressure is reduced by 0.015-0.025MPa per stage.

[0009] Preferably, the intermediate column section comprises a second-stage column section, a third-stage column section, and a fourth-stage column section; and the kettle temperature of the second-stage column section is controlled at 80-83℃, the column pressure is controlled at 0-0.02MPa, and the reflux ratio is controlled at 4:1, the kettle temperature of the third-stage column section is controlled at 84-87℃, the column pressure is controlled at -0.015-0MPa, and the reflux ratio is controlled at 5:1, and the kettle temperature of the fourth-stage column section is controlled at 87-90℃, the column pressure is controlled at -0.03--0.015MPa, and the reflux ratio is controlled at 6:1.

[0010] Preferably, the kettle temperature of the final-stage column section is controlled at 98-103℃, the column pressure is controlled at -0.045--0.03MPa, and the reflux ratio is controlled at 8:1.

[0011] Preferably, the catalytic isomerization packing is a sulfonic acid resin catalyst.

[0012] Preferably, the sulfonic acid resin catalyst is a perfluorosulfonic acid resin or a macroporous polystyrene sulfonic acid resin; preferably a perfluorosulfonic acid resin.

[0013] Preferably, the final-stage column section adopts BX500 type metal corrugated packing or high-silica ceramic corrugated packing.

[0014] Preferably, the first-stage column section adopts ceramic ball structured packing.

[0015] Preferably, the final-stage column section adopts a micro-channel structure, and the inner diameter of the micro-channel is 2-2.5mm.

[0016] Compared with the prior art, the anise oil multi-stage section rectification process of the present application does not need to repeatedly perform distillation heating, greatly reduces the heat-sensitive loss, and improves the yield and purity of trans-anethole product; in addition, it does not need a freezing crystallization process, has a short process cycle, and low energy consumption; the temperature of the multi-stage section rectification is lower than 110℃, which can protect the unique biological activity of the product, and has a broad application prospect in high-end markets such as high-grade cosmetics market. DETAILED DESCRIPTION

[0017] The following is a clear and complete description of the technical solutions in the embodiments of the present application. The described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application. If specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments, components used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0018] Example 1 A multi-stage fractional distillation process of fennel oil is as follows: The crude fennel oil 3572.3 Kg, wherein the trans-anethole content (GC) is 86.533%, is input into a multi-stage distillation column, and is subjected to a distillation process in turn through the first-stage column section, the intermediate column section, and the final column section to collect trans-anethole: the first-stage column section uses porcelain ball structured packing, and the column bottom temperature is controlled at 75℃, the column internal pressure is controlled at 0.03 MPa, and the reflux ratio is controlled at 3:1 to remove light components; the intermediate column section is set as a three-stage column section of the second-stage column section, the third-stage column section, and the fourth-stage column section, all of which use structured Nafion-XR perfluorosulfonic acid resin packing, the column bottom temperature of the second-stage column section is controlled at 80℃, the column internal pressure is controlled at 0.015 MPa, and the reflux ratio is controlled at 4:1, the column bottom temperature of the third-stage column section is controlled at 85℃, the column internal pressure is controlled at -0.01 MPa, and the reflux ratio is controlled at 5:1, the column bottom temperature of the fourth-stage column section is controlled at 87℃, the column internal pressure is controlled at -0.015 MPa, and the reflux ratio is controlled at 6:1, and the target component trans-anethole is gradually concentrated by gradually increasing the temperature; the final column section uses BX500 type metal corrugated packing, and the micro-channel structure with an inner diameter of 2.5 mm is used in the column, the column bottom temperature is controlled at 101℃, the column internal pressure is controlled at -0.038 MPa, and the reflux ratio is controlled at 8:1, and finally 2916.3 Kg of product is obtained, the total yield of the crude fennel oil as the raw material is 81.64%, which is identified as trans-anethole, the trans-anethole content (GC) is 99.912%, the cis-anethole content (GC) is 0.089%, and the trans-anethole yield is 94.34% based on the initial amount of trans-anethole in the raw material.

[0019] Product structure identification: 1 H-NMR (500 MHz, CDCl3) δ ppm: 7.29 (2H, d, J = 8.5 Hz, H-3, 5), 6.87 (2H, d, J = 8.5 Hz, H-2, 6), 6.38 (1H, d, J = 15.5 Hz, H-7), 6.12 (1H, m, H-8), 3.83 (3H, s, 1-OCH3), 1.89 (3H, d, J = 6.5 Hz, 8-CH3). 13C-NMR (125 MHz, CDC13) δ ppm: 158.59 (C-1), 138.83 (C-4), 130.35 (C-8), 126.89 (C-3, 5), 123.50 (C-7), 113.91 (C-2, C-6), 55.28 (1-OCH3), 18.43 (8-CH3). In accordance with the 1 H-NMR and 13 C-NMR data, the compound was determined to be trans-anethole.

[0020] Example 2 A multi-stage fractional distillation process for fennel oil was as follows: Crude fennel oil 3526.8 Kg, with trans-anethole content (GC) 87.362%, was fed into a multi-stage distillation column, and the trans-anethole was collected by performing a distillation process in the first-stage column section, the intermediate column section, and the final column section in sequence. The first-stage column section used porcelain ball structured packing, and the column bottom temperature was controlled at 77°C, the column internal pressure was controlled at 0.025 MPa, and the reflux ratio was controlled at 2:1 to remove light components. The intermediate column section was set as a three-stage column section including the second-stage column section, the third-stage column section, and the fourth-stage column section, all of which used structured Nafion-501 packing. The second-stage column section was controlled at a column bottom temperature of 81°C, a column internal pressure of 0.005 MPa, and a reflux ratio of 4:1. The third-stage column section was controlled at a column bottom temperature of 84°C, a column internal pressure of -0.015 MPa, and a reflux ratio of 5:1. The fourth-stage column section was controlled at a column bottom temperature of 87°C, a column internal pressure of -0.02 MPa, and a reflux ratio of 6:1, and the target component trans-anethole was gradually enriched by gradually increasing the temperature. The final column section used BX500 type metal corrugated packing, and the microchannel structure with an inner diameter of 2.25 mm was used in the column. The column bottom temperature was controlled at 98°C, the column internal pressure was controlled at -0.03 MPa, and the reflux ratio was controlled at 8:1. Finally, 2892.8 Kg of product was obtained, with a total yield of 82.02% based on the crude fennel oil as the raw material, a trans-anethole content (GC) of 99.923%, a cis-anethole content (GC) of 0.095%, and a trans-anethole yield of 93.89% based on the initial amount of trans-anethole in the raw material.

[0021] Example 3 A multi-stage fractional distillation process for fennel oil was as follows: The crude fennel oil 3510.5 Kg, wherein the trans-anethole content (GC) is 84.978%, is fed into a multi-stage rectification column, and is subjected to a rectification process in turn through a first-stage column section, an intermediate column section and a final column section, to collect trans-anethole: the first-stage column section uses porcelain ball structured packing, and the column bottom temperature is controlled at 80°C, the column internal pressure is controlled at 0.02 MPa, and the reflux ratio is controlled at 3:1 to remove light components; the intermediate column section is set as a three-stage column section of a second-stage column section, a third-stage column section and a fourth-stage column section, all of which use structured Nafion-H packing, the second-stage column section is controlled at a column bottom temperature of 83°C, a column internal pressure of 0 MPa and a reflux ratio of 4:1, the third-stage column section is controlled at a column bottom temperature of 87°C, a column internal pressure of -0.015 MPa and a reflux ratio of 5:1, and the fourth-stage column section is controlled at a column bottom temperature of 90°C, a column internal pressure of -0.03 MPa and a reflux ratio of 6:1, to gradually concentrate the target component trans-anethole by gradually increasing the temperature; the final column section uses BX500 type metal corrugated packing, and the internal diameter of the micro-channel structure used in the column is 2.5 mm, the column bottom temperature is controlled at 103°C, the column internal pressure is controlled at -0.045 MPa, and the reflux ratio is controlled at 8:1, and finally 2850.5 Kg of product is obtained, the total yield of crude fennel oil as the raw material is 81.20%, the trans-anethole content (GC) is 99.945%, the cis-anethole content (GC) is 0.086%, and the trans-anethole yield is 95.55% based on the initial amount of trans-anethole in the raw material.

[0022] Example 4 A multi-stage section rectification process for fennel oil is as follows: The crude fennel oil 3541.6 Kg, wherein the trans-anethole content (GC) is 86.122%, is fed into a multi-stage rectification column, and is subjected to a rectification process in turn through a first-stage column section, an intermediate column section and a final column section, to collect trans-anethole: the first-stage column section uses porcelain ball structured packing, and the column bottom temperature is controlled at 80°C, the column internal pressure is controlled at 0.02 MPa and the reflux ratio is controlled at 2:1 to remove light components; the intermediate column section is set as a three-stage column section of a second-stage column section, a third-stage column section and a fourth-stage column section, all of which use structured Nafion-H packing, the second-stage column section is controlled at a column bottom temperature of 82°C, a column internal pressure of 0 MPa and a reflux ratio of 4:1, the third-stage column section is controlled at a column bottom temperature of 85°C, a column internal pressure of -0.01 MPa and a reflux ratio of 5:1, and the fourth-stage column section is controlled at a column bottom temperature of 90°C, a column internal pressure of -0.028 MPa and a reflux ratio of 6:1, to gradually concentrate the target component trans-anethole by gradually increasing the temperature; the final column section uses high-silica ceramic corrugated packing, and the column uses a micro-channel structure with an inner diameter of 2.25 mm, the column bottom temperature is controlled at 101°C, the column internal pressure is controlled at -0.035 MPa and the reflux ratio is controlled at 8:1, and finally 2897.1 Kg of product is obtained, the total yield of crude fennel oil as the raw material is 81.8%, the trans-anethole content (GC) is 99.933%, the cis-anethole content (GC) is 0.113%, and the trans-anethole yield is 94.98% based on the initial amount of trans-anethole in the raw material.

[0023] Example 5 A multi-stage section rectification process for fennel oil is as follows: The crude fennel oil 3564.9 Kg, wherein the trans-anethole content (GC) is 85.797%, is fed into a multi-stage rectification column, and is subjected to a rectification process in turn through a first-stage column section, an intermediate column section and a final column section, to collect trans-anethole: the first-stage column section uses porcelain ball structured packing, and the column bottom temperature is controlled at 78°C, the column internal pressure is controlled at 0.015 MPa, and the reflux ratio is controlled at 31, to remove light components; the intermediate column section is set as a three-stage column section of a second-stage column section, a third-stage column section and a fourth-stage column section, all of which use structured macroporous polystyrene sulfonic acid resin Amberlyst 15 packing, the column bottom temperature of the second-stage column section is controlled at 81°C, the column internal pressure is controlled at 0.005 MPa, and the reflux ratio is controlled at 4:1, the column bottom temperature of the third-stage column section is controlled at 86°C, the column internal pressure is controlled at -0.01 MPa, and the reflux ratio is controlled at 5:1, the column bottom temperature of the fourth-stage column section is controlled at 88°C, the column internal pressure is controlled at -0.025 MPa, and the reflux ratio is controlled at 6:1, to gradually concentrate the target component trans-anethole by gradually increasing the temperature; the final column section uses BX500 type metal corrugated packing, and the micro-channel structure with an inner diameter of 2.25 mm is used in the column, the column bottom temperature is controlled at 101°C, the column internal pressure is controlled at -0.035 MPa, and the reflux ratio is controlled at 8:1, to finally obtain the product 2904.4 Kg, the total yield of crude fennel oil as the raw material is 81.47%, the trans-anethole content (GC) is 99.904%, the cis-anethole content (GC) is 0.152%, and the trans-anethole yield is 94.96% based on the initial amount of trans-anethole in the raw material.

[0024] Example 6 A multi-stage section rectification process for fennel oil is as follows: The crude fennel oil 355.3 Kg, wherein the trans-anethole content (GC) 87.025%, is put into a multi-stage rectification tower, and the trans-anethole is collected by sequentially performing rectification processes on the first-stage tower section, the middle tower section, and the last-stage tower section. The first-stage tower section uses porcelain ball structured packing, and the column bottom temperature is controlled at 79°C, the tower internal pressure is controlled at 0.01 MPa, and the reflux ratio is controlled at 2.5:1 to remove light components. The middle tower section is set as a three-stage tower section including the second-stage tower section, the third-stage tower section, and the fourth-stage tower section, all of which use structured Nafion-H packing, the column bottom temperature of the second-stage tower section is controlled at 83°C, the tower internal pressure is controlled at 0.005 MPa, and the reflux ratio is controlled at 4:1, the column bottom temperature of the third-stage tower section is controlled at 86°C, the tower internal pressure is controlled at -0.008 MPa, and the reflux ratio is controlled at 5:1, the column bottom temperature of the fourth-stage tower section is controlled at 89°C, the tower internal pressure is controlled at -0.028 MPa, and the reflux ratio is controlled at 6:1, and the target component trans-anethole is gradually enriched by gradually increasing the temperature. The last-stage tower section uses BX500 type metal corrugated packing, and the tower uses a micro-channel structure with an inner diameter of 2.1 mm, the column bottom temperature is controlled at 99°C, the tower internal pressure is controlled at -0.04 MPa, and the reflux ratio is controlled at 8:1, and finally 2884.6 Kg of product is obtained, the total yield of crude fennel oil as raw material is 81.18%, the trans-anethole content (GC) is 99.923%, the cis-anethole content (GC) is 0.104%, and the trans-anethole yield is 93.28% based on the initial amount of trans-anethole in the raw material.

[0025] Comparative Example 1 A multi-stage section rectification process for fennel oil is as follows: The crude fennel oil 3565.8 Kg, wherein the trans-anethole content (GC) 86.875%, is put into a multi-stage rectification tower, and the trans-anethole is collected by sequentially performing rectification processes on the first-stage tower section, the middle tower section, and the last-stage tower section. The first-stage tower section uses porcelain ball structured packing, and the column bottom temperature is controlled at 75°C, the tower internal pressure is controlled at 0.03 MPa, and the reflux ratio is controlled at 3:1 to remove light components. The middle tower section is set as a one-stage tower section, all of which use structured Nafion-XR packing, the column bottom temperature is controlled at 85°C, the tower internal pressure is controlled at -0.01 MPa, and the reflux ratio is controlled at 5:1. The last-stage tower section uses BX500 type metal corrugated packing, and the tower uses a micro-channel structure with an inner diameter of 2.5 mm, the column bottom temperature is controlled at 101°C, the tower internal pressure is controlled at -0.038 MPa, and the reflux ratio is controlled at 8:1, and finally 2486.2 Kg of product is obtained, the total yield of crude fennel oil as raw material is 69.72%, the trans-anethole content (GC) is 94.632%, the cis-anethole content (GC) is 0.38%, and the trans-anethole yield is 80.26% based on the initial amount of trans-anethole in the raw material.

[0026] Comparative Example 2 A multi-stage section rectification process for fennel oil is as follows: The crude fennel oil 3533.4 Kg, wherein the trans-anethole content (GC) is 87.945%, is input into a multi-stage rectification tower, and is subjected to a rectification process in turn through a first-stage tower section and a last-stage tower section to collect trans-anethole: the first-stage tower section adopts porcelain ball structured packing, and the tower kettle temperature is controlled at 75 ℃, the tower internal pressure is controlled at 0.03 MPa, and the reflux ratio is controlled at 3:1 to remove light components; the last-stage tower section adopts BX500 type metal corrugated packing, and the tower adopts a micro-channel structure with an inner diameter of 2.5 mm, the tower kettle temperature is controlled at 110 ℃, the tower internal pressure is controlled at -0.038 MPa, and the reflux ratio is controlled at 8:1, and finally 3096.2 Kg of product is obtained, the total yield of crude fennel oil as raw material is 87.63%, the trans-anethole content (GC) is 86.924%, the cis-anethole content (GC) is 0.872%, and the trans-anethole yield is 99.6% based on the initial amount of trans-anethole in the raw material.

[0027] Comparative Example 3 A multi-stage section rectification process for fennel oil is as follows: The crude fennel oil 3520.9 Kg, wherein the trans-anethole content (GC) is 86.125%, is input into a multi-stage rectification tower, and is subjected to a rectification process in turn through a first-stage tower section, an intermediate tower section and a last-stage tower section to collect trans-anethole: the first-stage tower section adopts porcelain ball structured packing, and the tower kettle temperature is controlled at 75 ℃, the tower internal pressure is controlled at 0.03 MPa, and the reflux ratio is controlled at 3:1 to remove light components; the intermediate tower section is set as a three-stage tower section of a second-stage tower section, a third-stage tower section and a fourth-stage tower section, all of which adopt BX500 type metal corrugated structured packing, the tower kettle temperature of the second-stage tower section is controlled at 80 ℃, the tower internal pressure is controlled at 0.015 MPa, and the reflux ratio is controlled at 4:1, the tower kettle temperature of the third-stage tower section is controlled at 85 ℃, the tower internal pressure is controlled at -0.01 MPa, and the reflux ratio is controlled at 5:1, the tower kettle temperature of the fourth-stage tower section is controlled at 87 ℃, the tower internal pressure is controlled at -0.015 MPa, and the reflux ratio is controlled at 6:1, and the target component trans-anethole is gradually concentrated by gradually increasing the temperature; the last-stage tower section adopts BX500 type metal corrugated packing, and the tower adopts a micro-channel structure with an inner diameter of 2.5 mm, the tower kettle temperature is controlled at 101 ℃, the tower internal pressure is controlled at -0.038 MPa, and the reflux ratio is controlled at 8:1, and finally 2827.8 Kg of product is obtained, the total yield of crude fennel oil as raw material is 80.31%, the trans-anethole content (GC) is 94.325%, the cis-anethole content (GC) is 0.456%, and the trans-anethole yield is 93.25% based on the initial amount of trans-anethole in the raw material.

[0028] Comparative Example 4 A multi-stage section rectification process for fennel oil is as follows: The crude fennel oil 3536.2 Kg, wherein the trans-anethole content (GC) 88.037%, is input into a multi-stage rectification tower, and is subjected to rectification procedures in turn through the first-stage tower section, the intermediate tower section and the final-stage tower section to collect trans-anethole: the first-stage tower section adopts porcelain ball structured packing, and the column bottom temperature is controlled at 75°C, the tower internal pressure is controlled at 0.03 MPa and the reflux ratio is controlled at 3:1 to remove light components; the intermediate tower section is set as a three-stage tower section of the second-stage tower section, the third-stage tower section and the fourth-stage tower section, all of which adopt structured Nafion-XR packing, the column bottom temperature of the second-stage tower section is controlled at 85°C, the tower internal pressure is controlled at 0.015 MPa and the reflux ratio is controlled at 4:1, the column bottom temperature of the third-stage tower section is controlled at 85°C, the tower internal pressure is controlled at -0.01 MPa and the reflux ratio is controlled at 5:1, the column bottom temperature of the fourth-stage tower section is controlled at 85°C, the tower internal pressure is controlled at -0.015 MPa and the reflux ratio is controlled at 6:1, and the target component trans-anethole is gradually enriched by gradually increasing the temperature; the final-stage tower section adopts BX500 type metal corrugated packing, and the tower adopts a micro-channel structure with an inner diameter of 2.5 mm, the column bottom temperature is controlled at 101°C, the tower internal pressure is controlled at -0.038 MPa and the reflux ratio is controlled at 8:1, and finally 2612.7 Kg of product is obtained, the total yield of crude fennel oil as raw material is 73.88%, the trans-anethole content (GC) is 95.427%, the cis-anethole content (GC) is 0.196%, and the trans-anethole yield is 83.92% based on the initial amount of trans-anethole in the raw material.

[0029] Comparative Example 5 A multi-stage section rectification process for fennel oil is as follows: The crude fennel oil 3524.9 Kg, wherein the trans-anethole content (GC) is 85.258%, is input into a multi-stage rectification tower, and is subjected to a rectification process in turn through a first-stage tower section, an intermediate tower section and a final-stage tower section, to collect trans-anethole: the first-stage tower section uses porcelain ball structured packing, and the column bottom temperature is controlled at 75°C, the tower internal pressure is controlled at 0.03 MPa, and the reflux ratio is controlled at 3:1 to remove light components; the intermediate tower section is set as a three-stage tower section of a second-stage tower section, a third-stage tower section and a fourth-stage tower section, all of which use structured Nafion-XR perfluorosulfonic acid resin packing, the column bottom temperature of the second-stage tower section is controlled at 80°C, the tower internal pressure is controlled at 0.01 MPa, and the reflux ratio is controlled at 4:1, the column bottom temperature of the third-stage tower section is controlled at 85°C, the tower internal pressure is controlled at -0.01 MPa, and the reflux ratio is controlled at 5:1, the column bottom temperature of the fourth-stage tower section is controlled at 87°C, the tower internal pressure is controlled at -0.01 MPa, and the reflux ratio is controlled at 6:1, and the target component trans-anethole is gradually concentrated by gradually increasing the temperature; the final-stage tower section uses BX500 type metal corrugated packing, and the tower uses a micro-channel structure with an inner diameter of 2.5 mm, the column bottom temperature is controlled at 101°C, the tower internal pressure is controlled at -0.038 MPa, and the reflux ratio is controlled at 8:1, and finally 2578.6 Kg of product is obtained, the total yield of crude fennel oil as the raw material is 73.15%, the trans-anethole content (GC) is 95.784%, the cis-anethole content (GC) is 0.192%, and the trans-anethole yield is 85.8% based on the initial amount of trans-anethole in the raw material.

[0030] Comparative Example 6 A multi-stage section rectification process for fennel oil is as follows: The crude fennel oil 3543.5 Kg, wherein the trans-anethole content (GC) 86.458%, is input into a multi-stage rectification tower, and is subjected to a rectification process in turn through a first-stage tower section, an intermediate tower section and a final-stage tower section, to collect trans-anethole: the first-stage tower section uses porcelain ball structured packing, and the column bottom temperature is controlled at 75°C, the tower internal pressure is controlled at 0.03 MPa, and the reflux ratio is controlled at 3:1 to remove light components; the intermediate tower section is set as a three-stage tower section of a second-stage tower section, a third-stage tower section and a fourth-stage tower section, all of which use structured Nafion-XR packing, the second-stage tower section is controlled at a column bottom temperature of 80°C, a tower internal pressure of 0.015 MPa and a reflux ratio of 4:1, the third-stage tower section is controlled at a column bottom temperature of 85°C, a tower internal pressure of -0.01 MPa and a reflux ratio of 5:1, and the fourth-stage tower section is controlled at a column bottom temperature of 87°C, a tower internal pressure of -0.015 MPa and a reflux ratio of 6:1, to gradually concentrate the target component trans-anethole by gradually increasing the temperature; the final-stage tower section uses BX500 type metal corrugated packing, and the tower uses a micro-channel structure with an inner diameter of 10.5 mm, the column bottom temperature is controlled at 101°C, the tower internal pressure is controlled at -0.038 MPa, and the reflux ratio is controlled at 8:1, and finally 2810.1 Kg of product is obtained, the total yield of crude fennel oil as raw material is 79.32%, the trans-anethole content (GC) is 96.989%, the cis-anethole content (GC) is 0.112%, and the trans-anethole yield is 91.72% based on the initial amount of trans-anethole in the raw material.

[0031] Comparative Example 7 A multi-stage section rectification process for fennel oil, as follows: The crude fennel oil 3582.3 Kg, wherein the trans-anethole content (GC) is 87.563%, is input into a multi-stage rectification tower, and is subjected to a rectification process in turn through a first-stage tower section, an intermediate tower section and a final-stage tower section, and trans-anethole is collected: the first-stage tower section adopts porcelain ball structured packing, and the column bottom temperature is controlled at 75 DEG C, the tower internal pressure is controlled at 0.03 MPa, and the reflux ratio is controlled at 3:1 to remove light components; the intermediate tower section is set as a three-stage tower section of a second-stage tower section, a third-stage tower section and a fourth-stage tower section, all of which adopt structured Nafion-XR perfluorosulfonic acid resin packing, the column bottom temperature of the second-stage tower section is controlled at 80 DEG C, the tower internal pressure is controlled at 0.015 MPa, and the reflux ratio is controlled at 4:1, the column bottom temperature of the third-stage tower section is controlled at 85 DEG C, the tower internal pressure is controlled at -0.01 MPa, and the reflux ratio is controlled at 5:1, the column bottom temperature of the fourth-stage tower section is controlled at 87 DEG C, the tower internal pressure is controlled at -0.015 MPa, and the reflux ratio is controlled at 6:1, and the target component trans-anethole is gradually concentrated by gradually increasing the temperature; the final-stage tower section adopts BX500 type metal corrugated packing, and the tower adopts a micro-channel structure with an inner diameter of 2.5 mm, the column bottom temperature is controlled at 115 DEG C, the tower internal pressure is controlled at 0.028 MPa, and the reflux ratio is controlled at 6:1, and finally 2576.6 Kg of product is obtained, the total yield of trans-anethole is 71.93% based on the crude fennel oil as raw material, the product is identified as trans-anethole, the trans-anethole content (GC) is 93.223%, the cis-anethole content (GC) is 0.146%, and the trans-anethole yield is 82.14% based on the initial amount of trans-anethole in the raw material.

[0032] In summary, the multi-stage section rectification process of the fennel oil of the present application can prepare high-purity and high-yield trans-anethole, and the process time is short, the energy consumption is low, and it is suitable for industrial production; without repeatedly distillation heating, the heat-sensitive loss is greatly reduced, the trans-anethole product yield and purity are improved; in addition, without a freezing crystallization process, the process cycle is short, and the energy consumption is low; the temperature of the multi-stage section rectification is lower than 110 DEG C, which can protect the unique biological activity of the product, and has a broad application prospect in high-end markets such as high-grade cosmetics market.

[0033] It will be obvious to a person skilled in the art that, without departing from the spirit and essential characteristics of the present application, the present application can be implemented in other specific forms. The present application is therefore not limited to the examples described above, but it can vary in the details within the ambit of the annexed claims, without thereby departing from the scope of the application. Consequently, all changes, modifications, additions or improvements coming into the idea and scope of the claims are considered to be a part of the present application.

[0034] Furthermore, it should be understood that although the specification is described in terms of embodiments, not every embodiment includes every feature or implementation described herein. The specification can include implicit combinations of explicitly mentioned features and / or implicit combinations of implicitly mentioned features. Such combinations are also expressly included within the scope of the specification and an embodiment.

Claims

1. A multi-stage fractional distillation process for fennel oil, characterized in that, Crude fennel oil is used as raw material, and multi-stage section distillation is carried out in the first-stage section, the middle-stage section and the last-stage section of the rectifying column. The first-stage section removes light components, the last-stage section refines trans-anethole, and the middle-stage section gradually increases the concentration of the target component trans-anethole by gradually increasing the temperature. The middle-stage section uses regular packing, and the packing used is catalytic isomerization packing.

2. A multi-stage fractional rectification process of fennel oil according to claim 1, characterized in that, The temperature of the kettle of the last-stage section is controlled at 98-103℃, the pressure in the column is controlled at-0.045--0.03MPa, and the reflux ratio is controlled at 8:

1.

3. The multi-stage fractional rectification process of fennel oil according to claim 1, characterized in that, The micro-channel structure is used in the column of the last-stage section, and the inner diameter of the micro-channel is 2-2.5mm.

4. The multi-stage fractional rectification process of fennel oil according to claim 1, characterized in that, The temperature of the kettle of the middle-stage section is controlled at 80-90℃, and the pressure in the column is controlled at-0.03-0.02MPa. The middle-stage section is set as three-stage section, and the temperature is gradually increased, the pressure is gradually reduced, and the reflux ratio is gradually increased.

5. A multi-stage fractional rectification process of fennel oil according to claim 4, characterized in that, In the middle-stage section, the temperature is increased by 2-5℃ in each stage, and the pressure is reduced by 0.015-0.025MPa in each stage.

6. A multi-stage fractional rectification process of fennel oil according to claim 5, characterized in that, The middle-stage section includes the second-stage section, the third-stage section and the fourth-stage section, the temperature of the kettle of the second-stage section is controlled at 80-83℃, the pressure in the column is controlled at 0-0.02MPa, and the reflux ratio is controlled at 4:1, the temperature of the kettle of the third-stage section is controlled at 84-87℃, the pressure in the column is controlled at-0.015-0MPa, and the reflux ratio is controlled at 5:1, and the temperature of the kettle of the fourth-stage section is controlled at 87-90℃, the pressure in the column is controlled at-0.03--0.015MPa, and the reflux ratio is controlled at 6:

1.

7. The multi-stage fractional rectification process of fennel oil according to claim 1, characterized in that, The temperature of the kettle of the first-stage section is controlled at 75-80℃, the pressure in the column is controlled at 0.02-0.03MPa, and the reflux ratio is controlled at 2-3:

1.

8. The multi-stage fractional rectification process of fennel oil according to claim 1, characterized in that, The catalytic isomerization packing is a sulfonic acid resin catalyst.

9. The multi-stage fractional rectification process of fennel oil according to claim 1, characterized in that, The sulfonic acid resin catalyst is one of perfluorosulfonic acid resin or macroporous polystyrene sulfonic acid resin.

10. The multi-stage fractional rectification process of fennel oil according to claim 1, characterized in that, The last-stage section uses BX500 type metal corrugated packing or high-silica ceramic corrugated packing, and the first-stage section uses ceramic ball regular packing.