Nicotine rectification device and nicotine purification method

Abstract

The invention relates to the technical field of purification, and provides a nicotine rectification device and a nicotine purification method, and the purification method comprises the following steps: adding a nicotine crude product into the rectification device for total reflux treatment; the rectification device is subjected to total reflux treatment and then is subjected to extraction treatment, and the extraction treatment comprises the following steps: extracting and detecting tower top fractions of the rectification device, after the composition of the tower top fractions is stable, extracting from the middle section of the rectification device to obtain a nicotine product, and continuously extracting the tower top fractions. According to the invention, the nicotine crude product is added into the rectification device and then is subjected to total reflux treatment, so that the high-purity nicotine product can be continuously extracted from the middle section of the rectification device. In addition, the heating time of nicotine in the purification process is short, and the problem of nicotine deterioration is effectively reduced. The method has the characteristics of high rectification yield, high purity, high efficiency and the like.

Description

Technical Field

[0001] The present application relates to the field of purification technology, and in particular to a nicotine distillation device and a nicotine purification method. Background Art

[0002] Nicotine, commonly known as nicotine. As one of the chemical components with a relatively high content in tobacco leaves, nicotine plays a very important role in biochemistry, pharmaceutical chemistry, and the tobacco industry. Nicotine is mainly extracted and purified from plants such as tobacco, but nicotine extracted and purified from plants such as tobacco usually contains many impurities and has low purity. Traditional technology also uses chemical synthesis of nicotine to prepare nicotine. Since the chemical synthesis process involves a variety of chemical reagents and by-products are generated during the preparation process, the resulting crude nicotine still has many impurities and is difficult to purify. Summary of the invention

[0003] Based on this, it is necessary to provide a nicotine distillation device with high efficiency and high purity and a nicotine purification method.

[0004] In a first aspect, the present application provides a method for purifying nicotine, the method for purifying nicotine comprising:

[0005] The crude nicotine is added to a distillation unit for total reflux treatment;

[0006] The distillation device is subjected to extraction treatment after the total reflux treatment, and the extraction treatment includes: extracting and detecting the top fraction of the distillation device, and when the composition of the top fraction is stable, extracting the nicotine product from the middle section of the distillation device, and continuously extracting the top fraction.

[0007] In some embodiments, during the total reflux treatment, the bottom temperature of the distillation device is 110° C. to 125° C., and the vacuum degree is 0.09 MPa to 0.1 MPa.

[0008] In some embodiments, the total reflux treatment time is 0.8h~2h.

[0009] In some embodiments, during the extraction process, the bottom temperature of the distillation device is 110° C. to 125° C., and the vacuum degree is 0.09 MPa to 0.1 MPa.

[0010] In some embodiments, the extraction treatment time is 8h~12h.

[0011] In some embodiments, the hourly extraction volume of the overhead fraction is 0.4% to 1% of the added volume of the crude nicotine product.

[0012] In some embodiments, the hourly extraction volume of the nicotine product is 7% to 9% of the added volume of the crude nicotine product.

[0013] In some embodiments, the top condensation temperature of the distillation device is 15-35°C.

[0014] In some embodiments, the height of the distillation column in the distillation device is 6m~8m.

[0015] In some embodiments, the extraction position of the nicotine product is 50% to 70% of the height of the distillation column.

[0016] In some embodiments, the distillation device includes at least one of a packed distillation device and a plate distillation device.

[0017] In some embodiments, the crude nicotine product comprises at least one of S-nicotine, α-nicotine, formaldehyde, formaldehyde condensate, benzene derivatives, pyridine, pyrrole derivatives, mesamine and cotinine.

[0018] In some embodiments, the mass content of nicotine in the crude nicotine product is 93% to 96%.

[0019] In a second aspect, the present application provides a nicotine distillation device, which is used to carry out the nicotine purification method as described in the first aspect, and the nicotine distillation device includes a distillation kettle, a distillation column, a condenser, a tower top extractor, and a tower middle section extractor;

[0020] The distillation kettle is connected to the distillation column, and the distillation kettle is used to heat the crude nicotine; the condenser is arranged at the top of the distillation column, and the condenser is used to condense the steam at the top of the distillation column; the top extractor is connected to the top of the distillation column, and the top extractor is used to extract the top fraction; the middle section extractor is connected to the middle section of the distillation column, and the middle section extractor is used to extract the middle section product of the distillation column.

[0021] Compared with the traditional technology, this application has at least the following beneficial effects:

[0022] In the present application, after the crude nicotine is added to the distillation device for full reflux treatment, the components in the crude nicotine are evenly distributed in the distillation device, among which light component impurities (such as alkanes, aldehydes, benzene series and pyridine heterocyclic byproducts, etc.) are enriched at the top of the distillation device, and heavy component impurities (such as nicotine analogs produced by heating of synthetic nicotine, such as mesamine, pronicotine and cotinine, etc.) are enriched in the bottom of the distillation device, and the middle section is a high-purity synthetic nicotine product. When the extraction of the top component is stable, that is, the distribution of the components in the distillation device is uniform, a high-purity (mass concentration ≥ 99.9%) synthetic nicotine product can be continuously extracted from the middle section. In addition, the heating time of nicotine in the purification process of the present application is short, which can effectively avoid the occurrence of problems such as thermal degradation and deterioration of nicotine during the purification process. The purification method of the present application has the characteristics of high efficiency, high purity, high yield and good quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of a nicotine distillation device provided in one embodiment of the present application.

[0024] Among them, 10-distillation kettle; 20-distillation column; 21-filler; 22-tower top distributor; 23-tower top liquid collecting tank; 24-tower middle section liquid collecting tank; 25-tower middle section distributor; 30-condenser; 40-tower top extractor; 50-tower middle section extractor. DETAILED DESCRIPTION

[0025] Below in conjunction with the embodiments and examples, the present application is further described in detail. These embodiments and examples are only used to illustrate the present application and are not used to limit the scope of the present application. The purpose of providing these embodiments and examples is to make the understanding of the disclosure of the present application more thorough and comprehensive. It should also be understood that the present application can be implemented in many different forms, and is not limited to the embodiments and examples described herein. Those skilled in the art can make various changes or modifications without violating the connotation of the present application, and the equivalent form obtained also falls within the protection scope of the present application. In addition, in the description below, a large number of specific details are given in order to provide a more comprehensive understanding of the present application. It should be understood that the present application can be implemented without one or more of these details.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0027] In this application, "optionally", "optional", and "optional" mean optional or dispensable, that is, any one of the two parallel schemes of "yes" or "no". If multiple "options" appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "optional" is independent.

[0028] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0029] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to an integer in the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical range disclosed in the present application should be understood to include any and all sub-ranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows for a broad range of quantitative intervals such as percentage intervals, ratio intervals, and ratio intervals.

[0030] All documents mentioned in this application are cited as references in this application, just as each document is cited as reference separately. Unless they conflict with the application purpose and / or technical solution of this application, the cited documents involved in this application are cited with all contents and all purposes. When the cited documents are involved in this application, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When the cited documents are involved in this application, the examples and preferred methods of the cited relevant technical features can also be incorporated into this application as references, but are limited to the implementation of this application. It should be understood that when the cited content conflicts with the description in this application, the present application shall prevail or be modified adaptively according to the description of this application.

[0031] In the conventional technology, crude nicotine is purified by intermittent distillation, which includes the following steps:

[0032] (1) It is necessary to extract the water and solvent residues at 0.05MPa~0.08MPa and below 80℃.

[0033] (2) The temperature is further increased to 80°C~100°C, and the vacuum is increased to 0.1MPa to extract the residual benzene series, aldehyde series and pyridine derivatives (pyridone, pyridine aldehyde, etc.).

[0034] (3) Maintaining the vacuum at 0.1 MPa, continue to raise the temperature to 110°C~120°C to extract a certain amount of nicotine product and transition fraction (impurities with a boiling point close to nicotine) until the exit product passes the test.

[0035] (4) Under vacuum of 0.1 MPa and 110°C to 120°C, a certain amount of synthetic nicotine is continuously extracted to clean and replace the distillation tower condenser and material pipeline to prevent residual impurities from contaminating the purity and odor of subsequent products.

[0036] (5) Continue to extract the nicotine product into the finished product can under vacuum of 0.1MPa and 110℃~120℃.

[0037] The nicotine distillation process in traditional technology is cumbersome to operate and needs to be operated in stages, which is a completely intermittent operation. During the distillation process, manual monitoring and operation are required at each step (intermittent distillation is extracted from the top of the tower, and the reflux ratio controller needs to be continuously adjusted according to the sampling test results to adjust the parameters of the reflux ratio). At the same time, in the process of extracting the front fraction and replacing the cleaning pipeline, the product loss is large and the distillation yield is low. Generally, the distillation yield is only between 80% and 85%. In addition, in traditional technology, the intermittent operation time is long, which causes nicotine to be heated for a long time, which is easy to produce degradation products such as nicotine analogues (mesamine, nornicotine, etc.), reducing the purity of the product and causing the aroma of synthetic nicotine to be impure and have a chemical smell.

[0038] Based on this, the present application provides a method for purifying nicotine, the method for purifying nicotine comprising:

[0039] The crude nicotine is added to a distillation unit for total reflux treatment;

[0040] The distillation device is subjected to extraction treatment after the total reflux treatment, and the extraction treatment includes: extracting and detecting the top fraction of the distillation device, and when the composition of the top fraction is stable, extracting the nicotine product from the middle section of the distillation device, and continuously extracting the top fraction.

[0041] In the present application, after the crude nicotine is added to the distillation device for full reflux treatment, the components in the crude nicotine are evenly distributed in the distillation device, wherein the light component impurities are enriched at the top of the distillation device, and the heavy component impurities are enriched in the bottom of the distillation device, and the middle section is a high-purity synthetic nicotine product. When the extraction of the top component is stable, that is, the distribution of the components in the distillation device is uniform, a high-purity (mass concentration ≥ 99.9%) synthetic nicotine product can be continuously extracted from the middle section. In addition, the heating time of nicotine in the purification process of the present application is short, which effectively avoids the occurrence of problems such as thermal degradation and deterioration of nicotine during the purification process. The purification method of the present application has the characteristics of high efficiency, high purity, high yield and good quality.

[0042] It should be noted that the composition stability of the top fraction in the present application refers to the composition change rate of each component of the top fraction being less than 5%. Taking the nicotine content in the top fraction as an example, when the change rate of the nicotine content in the top fraction obtained by continuous detection is less than 1%, the composition of the top fraction is considered to be stable. Optionally, when the composition of the top fraction is stable, the change rate of each component is 0.

[0043] It should be noted that the top condensate of the distillation unit includes the top extraction part and the reflux part, wherein the ratio of the reflux part to the extraction part is called the reflux ratio. Full reflux means that all the top condensate of the distillation unit is refluxed, that is, the reflux ratio is equal to infinity.

[0044] In some embodiments, during the total reflux treatment, the bottom temperature of the distillation device is 110°C~125°C, and the vacuum degree is 0.09MPa~0.1MPa.

[0045] In some embodiments, the total reflux treatment time is 0.8h~2h.

[0046] The present application selects the time for full reflux treatment as above, which can quickly establish gas-liquid equilibrium in the distillation tower, so that the light component impurities at the top of the tower are fully enriched, effectively avoiding failure of the distillation tower due to flooding, and incomplete removal of light component impurities, resulting in problems such as product purity and impure odor.

[0047] In some embodiments, during the extraction process, the bottom temperature of the distillation device is 110°C to 125°C, and the vacuum degree is 0.9MPa to 0.1MPa.

[0048] The temperature and vacuum degree of the extraction treatment selected in the present application as above can reduce the vaporization temperature of the synthetic nicotine, maintain a stable evaporation amount, reduce the liquid phase reflux resistance at the gas phase outlet of the distillation tower bottom, and ensure smooth reflux of the liquid phase to the bottom of the tower, thereby avoiding the degradation and deterioration of the synthetic nicotine and the destruction of the gas-liquid balance in the distillation tower.

[0049] In some embodiments, during the extraction process and the total reflux process, the bottom temperature and the vacuum degree are the same.

[0050] In some embodiments, the extraction treatment time is 8 hours to 12 hours. The present application selects the extraction treatment time as above to effectively avoid the problem of excessive distillation time causing degradation of synthetic nicotine and increased impurities.

[0051] In some embodiments, the hourly extraction volume of the overhead fraction is 0.4% to 1% of the added volume of the crude nicotine product, for example, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1.0%. Taking the added volume of the crude nicotine product as 1000L as an example, the extraction flow rate of the overhead fraction can be 4L / h to 10L / h.

[0052] The present application selects the extraction flow rate of the top fraction as above to ensure a constant composition of the extracted material and has no effect on the vacuum degree in the distillation device, thereby avoiding the problem of unstable top extraction components and large system vacuum fluctuations leading to a disruption of the mass transfer balance of the distillation system, and also avoiding the problem of low single-batch distillation yield due to excessive top extraction.

[0053] In some embodiments, the hourly extraction volume of the nicotine product is 7% to 9% of the added volume of the crude nicotine product. Taking the added volume of the crude nicotine product as 1000 L as an example, the extraction flow rate of the nicotine product can be 70 L / h to 90 L / h.

[0054] The present application selects the extraction flow rate of nicotine products as above to ensure that the composition of the extracted materials is constant and the system vacuum is not affected, so as to avoid excessive accumulation of liquid in the liquid collecting tank in the middle section of the tower, resulting in excessive temperature drop from the middle section to the upper section of the distillation tower, causing uneven heat transfer in the distillation tower. It can also ensure that the product extraction time is short, avoiding problems such as nicotine deterioration and degradation due to heat.

[0055] In some embodiments, the top condensation temperature of the distillation device is 15°C~35°C, for example, it can be 15°C, 17°C, 19°C, 21°C, 23°C, 25°C, 27°C, 29°C, 31°C, 33°C or 35°C.

[0056] The present application selects the tower top condensation temperature of the distillation device as above to ensure that the nicotine is fully cooled and no supercooled liquid is produced, which can avoid the problem that the gas in the upper section of the distillation tower is liquefied due to the low temperature of the reflux liquid in the upper section of the distillation tower, resulting in the mass transfer balance of the distillation tower being broken.

[0057] In some embodiments, the height of the distillation column in the distillation device is greater than or equal to 6 m. It can be selected from 6 m to 8 m, for example, it can be 6.0 m, 6.2 m, 6.4 m, 6.6 m, 6.8 m, 7.0 m, 7.2 m, 7.4 m, 7.6 m, 7.8 m or 8.0 m. It is understood that the distillation column refers to the part of the distillation device where the packing or the tray is arranged.

[0058] The height of the distillation column is selected as above in the present application, so as to effectively ensure the separation effect of nicotine in the distillation device and ensure the purity and efficiency of the nicotine product in the middle section. If the height of the distillation column is relatively low, it may cause poor nicotine separation effect and low purity; if the height of the distillation column is relatively high, it may cause high distillation energy consumption.

[0059] In some embodiments, the extraction position of the nicotine product is 50% to 70% of the height of the distillation column, for example, it can be 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68% or 70%. It is understood that when the height of the distillation column is H, the extraction position of the nicotine product is located on the side of the distillation column close to the top of the tower, and the extraction height is 50% to 70% of H.

[0060] The present application selects the extraction position of the nicotine product as above, which not only keeps the product extraction flow rate constant and the component composition stable, but also does not affect the liquid phase flow rate in the middle and lower sections of the distillation tower, thereby avoiding the occurrence of problems such as too low liquid phase flow rate in the distillation tower and insufficient return of the heavy components to the bottom of the tower with the liquid phase, resulting in unstable product composition.

[0061] In some embodiments, the distillation device includes at least one of a packing type distillation device and a tray type distillation device. It is understandable that the distillation device of the present application can reasonably select tray parameters, packing parameters and tower diameter according to distillation needs.

[0062] In some embodiments, the crude nicotine product comprises at least one of S-nicotine, α-nicotine, formaldehyde, formaldehyde condensate, benzene derivatives, pyridine, pyrrole derivatives, mesamine and cotinine.

[0063] In some embodiments, the mass content of nicotine in the crude nicotine product is 93% to 96%.

[0064] In some embodiments, crude nicotine can be added to the bottom of the distillation unit. It is understood that when the level of crude nicotine in the bottom is low, for example, below the stirring level, the purification operation is stopped. After the crude nicotine is added to the bottom of the tower, a total reflux treatment is performed again, and then the nicotine is extracted and purified. The stirring level refers to the level at which the stirring paddle cannot contact and stir the liquid.

[0065] Exemplarily, a method for purifying the above-mentioned nicotine is provided, comprising the following steps:

[0066] S1. Add the crude nicotine into the bottom of the distillation unit, and the top condensation temperature is 15℃~35℃.

[0067] S2. Start the distillation device with the bottom temperature at 110°C~125°C and the vacuum degree at 0.09MPa~0.1MPa, and perform full reflux treatment.

[0068] S3. After 0.8h~2h of total reflux treatment, the top fraction of the distillation device is extracted and tested. The hourly extraction volume of the top fraction is 0.4%~1% of the added volume of the crude nicotine product. When the composition of the top fraction is stable, the top fraction is continuously extracted, and nicotine products are extracted in the middle section of the distillation device. The hourly extraction volume of the nicotine product is 7%~9% of the added volume of the crude nicotine product.

[0069] S4. When the liquid level in the tower kettle is lower than the stirring level, stop extraction and close the distillation device, and add the top fraction into the tower kettle.

[0070] S5. Repeat steps S1-S4 to achieve continuous purification of nicotine.

[0071] The second aspect of the present application provides a nicotine distillation device, which is used to carry out the nicotine purification method as described in the first aspect. Figure 1 As shown, the nicotine distillation device includes a distillation kettle 10, a distillation column 20, a condenser 30, a tower top extractor 40 and a tower middle section extractor 50.

[0072] The distillation kettle 10 is connected to the distillation column 20, and the distillation kettle 10 is used to heat the crude nicotine; the condenser 30 is arranged at the top of the distillation column 20, and the condenser 30 is used to condense the steam at the top of the distillation column 20; the top extractor 40 is connected to the top of the distillation column 20, and the top extractor 40 is used to extract the top fraction; the middle section extractor 50 is connected to the middle section of the distillation column 20, and the middle section extractor 50 is used to extract the middle section product of the distillation column 20.

[0073] Optionally, the distillation column 20 is provided with a packing 21, a tower top distributor 22, a tower top liquid collecting tank 23, a tower middle section liquid collecting tank 24 and a tower middle section distributor 25. Among them, the packing 21 is filled in the distillation column. The tower top distributor 22 and the tower top liquid collecting tank 23 are respectively arranged at the top of the distillation column 20, the tower top distributor 22 is used to disperse the fraction condensed by the condenser 30, the tower top liquid collecting tank 23 is used to collect the tower top fraction, and the tower top extractor 40 can be connected to the tower top liquid collecting tank 23. The tower middle section liquid collecting tank 24 and the tower middle section distributor 25 are arranged in the middle of the distillation column 20, respectively used to disperse the products of the tower middle section and collect the products of the tower middle section, and the tower middle section extractor 50 can be connected to the tower middle section liquid collecting tank 24.

[0074] The embodiments of the present application will be described in detail below in conjunction with examples. It should be understood that these examples are only used to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are preferably referred to the guidance provided in the present application, and can also be based on the experimental manual or normal conditions in this area, can also be based on the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0075] The impurity content in the nicotine products in the following examples and comparative examples was detected using GCMS (gas chromatography-mass spectrometry). The detection conditions are as follows:

[0076] 1. Sample Pretreatment

[0077] Take 20 μL of nicotine sample, dilute it to 1 mL with methanol, filter it through a 0.22 μm membrane, and analyze it by GC-MS.

[0078] 2. Instrument conditions

[0079] 2.1 Gas chromatograph conditions

[0080] Chromatographic column: DB-WAX capillary column; the stationary phase is polyethylene glycol; specifications [30m (length) × 0.25mm (inner diameter) × 0.25μm (film thickness)].

[0081] Inlet temperature: 250℃.

[0082] Carrier gas: helium (purity ≥ 99.999%), constant flow rate: 2 mL / min.

[0083] Injection volume: 1 µL, split injection, split ratio: 100:1.

[0084] Program temperature rise: initial temperature 60°C, hold for 2 min, increase to 230°C at a rate of 10°C / min, hold for 8 min.

[0085] 2.2 Mass spectrometry conditions

[0086] Chromatography and mass spectrometry interface temperature: 250℃.

[0087] Ionization method: electron impact source (EI).

[0088] Ionization energy: 70eV.

[0089] Ion source temperature: 230 °C.

[0090] Solvent delay: 3 min.

[0091] Mass scan range: 50m / z~350m / z.

[0092] Scan mode: full scan mode.

[0093] Nicotine purity was tested by gas chromatography under the following test conditions:

[0094] 1. Sample Pretreatment

[0095] Take 20 μL of nicotine sample, dilute it to 1 mL with methanol, filter it through a 0.22 μm filter membrane, and analyze it by GC.

[0096] 2. Instrument conditions

[0097] Gas chromatograph conditions

[0098] Chromatographic column: DB-5 capillary column; the stationary phase is polyethylene glycol; specifications [30m (length) × 0.25mm (inner diameter) × 0.25μm (film thickness)].

[0099] Inlet temperature: 250℃.

[0100] Carrier gas: helium (purity ≥ 99.999%), constant flow rate: 1 mL / min; hydrogen flow rate 30 mL / min, air flow rate 300 mL / min.

[0101] Injection volume: 1 µL, split injection, split ratio: 40:1.

[0102] Programmed temperature: The column oven temperature was initially programmed at 100°C, then increased to 280°C at 20°C / min and maintained at that temperature for 3 min.

[0103] The preparation method of the crude nicotine product used in the following examples and comparative examples comprises the following steps:

[0104] Add 1500L of toluene to the condensation reactor, replace with nitrogen, add 110kg of sodium hydrogen, heat to 84℃ and keep warm for 2h, cool to 45℃ for standby use. Add 2000L of xylene, 454kg of ethyl nicotinate and 372kg of N-vinyl pyrrolidone to the preparation reactor, keep warm at 30℃, stir and dissolve, then transfer to the feeding kettle.

[0105] Control the temperature at 40℃ and drip the reaction solution in the feed kettle into the condensation reactor. Pay attention to the release of gas during the process. After the dripping is completed, heat it to 75℃ and keep it for 4 hours. TCL (thin layer chromatography) tests that the reaction of nicotinate ethyl ester is complete. Cool it down to below 20℃ for use.

[0106] Add 1500kg of concentrated hydrochloric acid and 750kg of water to the acidolysis kettle, stir and cool to below 10°C, slowly transfer the reaction liquid in the condensation reaction kettle to the acidolysis kettle, stir for 1h after transfer, separate the layers, transfer the lower water layer to the reflux kettle, slowly heat up to evaporate the low boiling point solvent, start reflux at 100°C, and reflux for 8h until the reaction is complete. Cool down to 20°C, drop 40% NaOH to adjust the pH to 1.25, add dichloromethane for extraction three times, and the amount of dichloromethane added each time is 1000L. Combine dichloromethane to a 5000L desolventizing kettle, evaporate to 80°C at normal pressure to recover dichloromethane, and transfer the desolventizing kettle bottom liquid to a 500L mysmine distillation kettle to decompress and evaporate mysmine. 320kg of mysmine is obtained, and its molar yield is 76.8%.

[0107] Add 600kg of 20% imine reductase (IR), 450kg of 20% glucose dehydrogenase (GDH), 750kg of glucose, 150kg of 1% NADP (coenzyme II) and 1500kg of pure water to the reduction reactor and stir. Control the temperature at 27℃ and pH 7.2. Add 750kg of 50% myosamine aqueous solution, control the dripping speed, monitor myosamine once every hour, and control the mass concentration of myosamine in the process to ≤0.1%. After the dropwise addition is complete and the reaction is complete, add 450kg of 37% formaldehyde aqueous solution and stir for use.

[0108] Add 1500kg of formic acid with a mass concentration of 20% to the methylation kettle, heat it to 90℃, and slowly inject the reaction liquid in the reduction reactor, control the temperature at 85℃. After injection, continue stirring for 3h, and GC (gas chromatography) tracks the reaction to be complete. Cool down to 20℃ and filter by plate and frame. The filtrate is extracted three times with dichloromethane, using 1000L of dichloromethane each time, and the dichloromethane is combined to the desolventizing kettle, and dichloromethane is recovered at 80℃ under normal pressure. The bottom liquid of the desolventizing kettle is transferred to a 500L nicotine rectification kettle to decompress and evaporate the nicotine. 342kg of crude nicotine is obtained.

[0109] The crude nicotine product prepared above has a mass purity of 95.875%, and impurities include light components (solvent residues, formaldehyde and its condensation products, and benzene derivatives), transition fractions (pyridine / pyrrole derivatives, neonicotinoids and pronicotine, etc.) and heavy components (nicotine analogues such as α-nicotine, nornicotine, mesamine and cotinine).

[0110] The following examples and comparative examples all adopt Figure 1The distillation device shown includes a distillation kettle 10, a distillation column 20, a condenser 30, a tower top extractor 40 and a tower mid-section extractor 50, wherein the packing 21 in the distillation column 20 is a DY1000 type wire mesh corrugated structured packing, and the distillation column 20 is also provided with a tower top distributor 22, a tower top liquid collecting tank 23, a tower mid-section liquid collecting tank 24 and a tower mid-section distributor 25. The diameter of the distillation column is DN300, the packing is two sections of packing with a height of 3m, and the tower mid-section liquid collecting tank is arranged between the two sections of packing.

[0111] Example 1

[0112] S1. Add 1000 kg of crude nicotine into the distillation kettle of the distillation device.

[0113] S2. Start the distillation device, the bottom temperature is 115°C, the vacuum degree is 0.1MPa, the top condensation temperature is 25°C, and the top material vapor is cooled by the condenser and then refluxed for full reflux treatment.

[0114] S3. After 1 hour of total reflux treatment, the top fraction is extracted through the top extraction pump at a flow rate of 5L / h, and the top fraction is tested. When the composition of the top fraction is stable, the top fraction is continuously extracted, and nicotine products are extracted in the middle section of the distillation device at a flow rate of 80L / h.

[0115] S4. After 10 hours of distillation, the liquid level in the distillation kettle was lower than the stirring level, that is, the mass of the material in the distillation kettle was 20 kg, and the production of nicotine product and the production of the top fraction were stopped in turn. Among them, 930 kg of nicotine product was produced, the distillation yield was 93%, and the product composition was shown in Table 1; 50 kg of the top fraction (including nicotine and light component impurities) was produced and added to the distillation kettle.

[0116] S5. Add 930 kg of crude nicotine into the distillation kettle, and repeat steps S2 to S4 to achieve continuous purification of nicotine.

[0117] Table 1

[0118]

[0119] Example 2

[0120] Purification was carried out according to the method of Example 1, except that the extraction flow rate of the top fraction was 2 L / h, the distillation yield after purification was 95%, and the purity was 99.95%.

[0121] Example 3

[0122] Purification was carried out according to the method of Example 1, except that the extraction flow rate of the nicotine product was 50 L / h, the distillation yield after purification was 83%, and the purity was 99.94%.

[0123] Example 4

[0124] Purification was performed according to the method of Example 1, except that the extraction flow rate of the nicotine product was 100 L / h, the distillation yield after purification was 96%, and the purity was 99.75%.

[0125] Example 5

[0126] Purification was carried out according to the method of Example 1, except that the condensation temperature at the top of the tower was 40° C., and the distillation yield after purification was 78% and the purity was 99.82%.

[0127] Comparative Example 1

[0128] S1. Add 1000 kg of crude nicotine to the distillation kettle, start the distillation device, set the kettle temperature to 70°C, the vacuum degree to 0.08 MPa, set the reflux ratio controller to full extraction, extract the solvent residue and light components such as water in the crude nicotine, and stop extraction after observing that no liquid is extracted after 1 hour, to obtain 12 kg of the front fraction.

[0129] S2. Raise the temperature of the distillation kettle to 115°C, adjust the vacuum degree to 0.1MPa, set the reflux ratio to 3:1, and extract transition fractions such as benzene series, formaldehyde and its derivatives, pyridine / pyrrole analogs and nicotine analogs. When the nicotine content in the extracted sample is stable and meets the extraction requirements, continue to extract products to fully replace the residual front fractions and transition fractions in the distillation tower condenser and material pipeline. Among them, the extraction amount of transition fraction is 70kg, and the extraction of qualified nicotine for replacement is about 30kg.

[0130] S3. The temperature of the distillation kettle was maintained at 115°C, the vacuum degree was 0.1 MPa, and the reflux ratio was 3:1. Nicotine products were extracted. Sampling and testing were continued during the extraction process. When the material in the distillation kettle was 400 kg, in order to prevent the "flying temperature" phenomenon (as the material decreases, the heating source remains unchanged, the material temperature will rise suddenly) from affecting the product quality, the reflux ratio was increased to 4:1, and the extraction was continued until the material level reached the stirring level of the distillation kettle (the material remained 20 kg). The distillation was stopped. The nicotine product extraction time was 15 hours, and 868 kg of nicotine products were obtained. The composition of the nicotine product is shown in Table 2.

[0131] Table 2

[0132]

[0133] It can be seen from the above embodiments and comparative examples that:

[0134] (1) Compared with Example 1, it can be seen that Example 2 reduces the extraction flow rate of the top fraction. Although the distillation yield and purity are improved, the distillation time is prolonged and the energy consumption is increased. Moreover, as the distillation time increases, that is, the heating time of the nicotine product in the distillation device increases, the nicotine may be decomposed and deteriorated by heat, thereby affecting the quality of the nicotine.

[0135] (2) Compared with Example 1, it can be seen that Example 3 reduces the extraction flow rate of the nicotine product. Although the purity of the extracted product is improved, the distillation time is increased due to the reduced product extraction flow rate. When the extraction of the tower top remains unchanged, the extraction of the tower top fraction is increased, resulting in a decrease in the distillation yield. In addition, the problem of nicotine decomposition and deterioration due to thermal decomposition caused by the long distillation time may occur.

[0136] (3) Compared with Example 1 and Example 4, it can be seen that Example 4 increases the extraction flow rate of nicotine products. Although it greatly shortens the distillation time and improves the distillation yield, the heavy component impurities in the nicotine product will increase, resulting in a decrease in product purity and affecting the quality of nicotine.

[0137] (4) Compared with Example 1, it can be seen that Example 5 increases the condensation temperature at the top of the tower, resulting in that the nicotine vapor cannot be completely cooled. The non-condensable gas formed will be sucked away by the vacuum system. At the same time, the liquid reflux rate is reduced, which increases the heavy components in the nicotine product. Not only is the distillation yield low, but the product purity is also low.

[0138] (5) Compared with Example 1 and Comparative Example 1, the mass purity of nicotine in the top fraction extracted in Example 1 is 98.513%, wherein the impurities include light components (solvent residues, formaldehyde and its condensation products and benzene series) and transition fractions (pyridine / pyrrole derivatives, neonicotinoids and pronicotine, etc.), that is, the present application can extract light components and transition fractions in the nicotine crude product from the top of the tower after full reflux operation, without the need for multiple distillation separations, thereby effectively improving the purification efficiency. Furthermore, the nicotine product obtained in Example 1 of the present application is 930 kg, the distillation yield is 93%, the purity of the nicotine product is 99.912%, the number of impurities is 6, the content of heavy components such as nicotine analogs is extremely low, and there is no residual benzene series. The nicotine product obtained in Comparative Example 1 is 868 kg, the distillation yield is 86.8%, the purity of the nicotine product is 99.767%, the number of impurities is 14, among which the content of nicotine analogues such as myosamine and cotinine is significantly higher than that in Example 1, and there are still trace amounts of benzene series residues.

[0139] In summary, after the crude nicotine is added to the distillation device for full reflux treatment, the components in the crude nicotine are evenly distributed in the distillation device, among which light component impurities (such as alkanes) are enriched at the top of the distillation device, and heavy component impurities (such as nicotine analogs produced by heating of synthetic nicotine) are enriched in the bottom of the distillation device, and the middle section is a high-purity synthetic nicotine product. When the extraction of the top component is stable, that is, the distribution of the components in the distillation device is uniform, a high-purity (mass concentration ≥ 99.9%) synthetic nicotine product can be continuously extracted from the middle section. In addition, the heating time of nicotine in the purification process of the present application is short, which effectively avoids the occurrence of problems such as thermal degradation and deterioration of nicotine during the purification process. The purification method of the present application has the characteristics of high efficiency, high purity, high yield and good quality.

[0140] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0141] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the application. It should be noted that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for purifying nicotine, characterized in that: The nicotine purification method comprises: The crude nicotine is added to a distillation unit for total reflux treatment; The distillation device is subjected to extraction treatment after the total reflux treatment, and the extraction treatment includes: extracting and detecting the top fraction of the distillation device, and when the composition of the top fraction is stable, extracting the nicotine product from the middle section of the distillation device, and continuously extracting the top fraction.

2. The method for purifying nicotine according to claim 1, characterized in that: The full reflux process satisfies at least one of the following conditions: (1) During the total reflux treatment, the bottom temperature of the distillation unit is 110°C to 125°C, and the vacuum degree is 0.09MPa to 0.1MPa; (2) The total reflux treatment time is 0.8h~2h.

3. The method for purifying nicotine according to claim 1, characterized in that: The extraction process satisfies at least one of the following conditions: (1) During the extraction process, the bottom temperature of the distillation unit is 110°C to 125°C, and the vacuum degree is 0.09MPa to 0.1MPa; (2) The extraction and treatment time is 8h~12h.

4. The method for purifying nicotine according to claim 1, characterized in that: The extraction process also satisfies at least one of the following conditions: (1) The hourly extraction volume of the overhead fraction is 0.4% to 1% of the added volume of the crude nicotine product; (2) The hourly extraction volume of the nicotine product is 7% to 9% of the added volume of the crude nicotine product.

5. The method for purifying nicotine according to claim 1, characterized in that: The top condensation temperature of the distillation device is 15°C to 35°C.

6. The method for purifying nicotine according to claim 1, wherein: The height of the distillation column in the distillation device is 6m~8m.

7. The method for purifying nicotine according to claim 1, characterized in that: The extraction position of the nicotine product is 50% to 70% of the height of the distillation column.

8. The method for purifying nicotine according to claim 1, characterized in that: The distillation device comprises at least one of a packing type distillation device and a tray type distillation device.

9. The method for purifying nicotine according to any one of claims 1 to 8, characterized in that: The nicotine purification method further satisfies at least one of the following conditions: (1) The crude nicotine product comprises at least one of S-nicotine, α-nicotine, formaldehyde, formaldehyde condensate, benzene derivatives, pyridine, pyrrole derivatives, mesamine and cotinine; (2) The mass content of nicotine in the crude nicotine product is 93% to 96%.

10. A nicotine distillation device, characterized in that: The nicotine distillation device is used to carry out the nicotine purification method according to any one of claims 1 to 9, wherein the nicotine distillation device comprises a distillation kettle, a distillation column, a condenser, a tower top extractor and a tower middle section extractor; The distillation kettle is connected to the distillation column, and the distillation kettle is used to heat the crude nicotine; the condenser is arranged at the top of the distillation column, and the condenser is used to condense the steam at the top of the distillation column; the top extractor is connected to the top of the distillation column, and the top extractor is used to extract the top fraction; the middle section extractor is connected to the middle section of the distillation column, and the middle section extractor is used to extract the middle section product of the distillation column.

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