A method for co-producing long carbon chain cyanic acid
By co-producing cyano acids while producing fatty dinitriles, the problem of lack of monomers and mature process routes for synthesizing nylon 9 and nylon 10 in the prior art is solved, and the effects of loose process parameters, reduced investment costs and stable product yields are achieved.
Patent Information
- Application Number
- CN202411983256.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2025-04-08
AI Technical Summary
The lack of monomers and mature process routes for synthesizing nylon 9 and nylon 10 in the prior art has led to the fact that these products have not been produced in industrialized on the market. In particular, cyano acid products have important market value as pre-intermediates, but their process requirements are high and their raw material ratios are harsh, resulting in low product yields.
The method of co-production of cyano acids is adopted to produce cyano acids at the same time while producing fatty dinitriles. The simultaneous production of both products is achieved through semiaminolysis reaction, acidification separation and vacuum dehydration. Compared with the original technology, the process requirements are relatively loose, allowing for deviations in process parameter control, which only affects the product proportion without reducing the total yield.
It is achieved that without changing the proaminogenization device, the investment cost is greatly reduced, and the ratio of the two products can be flexibly adjusted, while the total yield is stable and the product quality is good.
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Figure CN119775162A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a method for co-producing long-carbon-chain cyanic acid, belonging to the technical field of fine chemicals. Background Art
[0002] Polyamide resin is a large category of engineering plastics, which has the characteristics of good flexibility, high mechanical strength, low density, acid and alkali corrosion resistance, and excellent electrical insulation properties.
[0003] Because of its excellent performance, it is widely used in many fields such as automobiles, medical equipment, electronic appliances, and military industry.
[0004] At present, there are many varieties of polyamide resins in production and industrial application, such as double-number nylon 66, nylon 610, nylon 612, nylon 1010, nylon 1012, nylon 1212, etc., and single-number nylon 6, nylon 11, nylon 12, etc. However, there is no report on nylon 9 and nylon 10 in the market. The main reason is that there is no monomer and mature process route for synthesizing nylon 9 and nylon 10. In particular, nylon 9 is a product with very superior performance, and cyanic acid products are the pre-intermediates for synthesizing single-number nylon monomers. Therefore, this type of product has extremely important market value.
[0005] Perhaps due to the limitation of raw material sources and technical conditions, as far as the applicant knows, there has been no report on the industrial production of cyanic acid products, except for an invention patent applied for by the applicant in August 2017: CN107325022A A method for preparing long-chain cyanic acid. However, the applicant's technical process at that time had high requirements and strict requirements on the raw material ratio. If not careful, it would lead to low product yield.
[0006] In view of the shortcomings of the above-mentioned technologies, the present invention provides a method for co-producing long-chain cyanic acid. Summary of the invention
[0007] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for co-producing long-chain cyanic acid. The present invention adopts an innovative idea and proposes a method for co-producing cyanic acid. By using a device for producing dinitrile, two products can be produced simultaneously, that is, cyanic acid can be co-produced while producing fatty dinitrile. Compared with the original patent (CN107325022A A method for preparing long-chain cyanic acid), the process requirements are relatively loose, and deviations in process parameter control are allowed, which will only affect the ratio of the two products, but the total yield will not be reduced.
[0008] In order to achieve the above technical objectives, the technical solution adopted by the embodiment of the present invention is: A method for co-producing long-chain cyanic acid comprises the following steps: Step S1, semi-ammoniation reaction: a fatty diacid and a catalyst are put into an ammoniation reactor, nitrogen replaces oxygen in the ammoniation reactor, heats and melts to 190-195° C., introduces ammonia to react and heats to 215-225° C., continues to heat to 237-243° C. for 2-3 hours, then heats to 270-290° C., reacts for 6-8 hours and ends, during the reaction, the vapor phase condensate is collected in an oil-water separator, the upper layer is an oil phase, the lower layer is an aqueous phase, the oil phase is dynamically refluxed to the ammoniation reactor to continue the reaction, the aqueous phase is collected in the oil-water separator, and is separated in the next step; the amoniation reactor contains a crude fatty dinitrile; Step S2, acidification separation: after the semi-ammoniation reaction is completed, the water phase in the oil-water separator is transferred to an acidification separator, acidified to pH=5.0-5.5 by adding acid, and the solid is separated; Step S3, vacuum dehydration: the solid obtained in step S2 is placed in a vacuum dehydration reactor, a dehydrating agent is added, vacuumized and heated to melt, the temperature is raised to 220-230° C. with stirring, and dehydrated for 2-3 hours to obtain a cyanic acid product.
[0009] In step S1, the oil phase components in the oil-water separation include diamide, cyanoamide and fatty dinitrile; the water phase components include cyanic acid, carboxylic acid amide and dibasic acid.
[0010] Furthermore, in step S1, the flow rate of ammonia gas introduced per kilogram of fatty diacid is 30 to 60 dm 3 / h, the pressure of the ammonia buffer bag is 0.2-0.3MPa, and the stirring speed of the ammonia reactor is 60-90r / min.
[0011] As mentioned above, the ammonia flow rate per kilogram of fatty diacid is 30-60 dm 3 / h, mainly because the ammonia flow rate is less than 30dm 3 / h, the reaction speed slows down. In addition, due to the small gas flow rate, cyanic acid, carboxylic acid amide or its ammonium salt in the reaction system is not easily taken out with the gas flow, resulting in a small amount of target product cyanic acid or its ammonium salt, carboxylic acid amide or its ammonium salt in the condensate water phase, and the purpose of co-production of cyanic acid cannot be achieved; the ammonia flow rate is greater than 60dm 3 / h, the amidation reaction rate will be accelerated, and the flow rate of excess ammonia and water vapor in the system will increase. If the ammonia flow rate is too large, more fatty diacids will be entrained into the water phase of the oil-water separator by the airflow, and the purpose of co-production of cyanic acid will also not be achieved.
[0012] As mentioned above, the temperature reaches 190-195°C, and ammonia is introduced until the temperature reaches 215-225°C. At this stage, the main reaction is the reaction of fatty diacid and ammonia to form salts; the temperature rises to 237-243°C for 2-3 hours, and the reaction is mainly salt dehydration to form amides. At this time, the products include carboxyl amide, fatty diacid monoammonium salt, fatty diacid ammonium salt or monoamic acid ammonium salt, and a small amount of fatty diacid, fatty diamide, etc. Because the amide group is unstable, the organic matter contained in the water phase obtained in the oil-water separator at this time is mainly fatty monoamic acid ammonium salt, carboxyl amide, and cyanic acid.
[0013] As mentioned above, the reaction temperature is finally raised to 270-290°C for 6-8h. In this temperature range, the reaction is mainly amide dehydration, such as the conversion of the reaction intermediate carboxyl amide to cyanic acid, and the conversion of fatty diamide to fatty dinitrile. However, the proportion of fatty dinitrile is significantly less than that of cyanic acid. Because the reaction rate of amide to nitrile is relatively slow, more cyanic acid can be obtained. At the same time, a balanced conversion reaction can also occur between amides to generate cyanic acid. If the reaction temperature exceeds 270°C, the reaction rate of generating fatty dinitrile will be accelerated. If the reaction temperature reaches 290-300°C, the reaction rate will increase by about an order of magnitude, and the amount of cyanic acid obtained will be reduced.
[0014] Further, in step S1, the inlet end of the ammonia reactor is connected to the gas outlet end of the ammonia pressure stabilizing bag, an ammonia flowmeter is provided between the ammonia pressure stabilizing bag and the ammonia reactor, the outlet end of the ammonia reactor is connected to the inlet end of the condenser, the outlet end of the condenser is connected to the inlet end of the oil-water separator, the outlet end of the oil-water separator is connected to the inlet end of the ammonia reactor, and the ammonia reactor is provided with an electric heating device and a stirring device.
[0015] Furthermore, in step S1, the fatty diacid is a dibasic acid with a carbon chain of C9-C12, and is one of azelaic acid, sebacic acid, undecanedioic acid and dodecanedioic acid.
[0016] Furthermore, in step S1, the catalyst is an oxide containing zinc or aluminum or a metal salt containing a molybdenum component, or is silica gel, and the added amount is 2.5% to 5% of the mass of the fatty diacid.
[0017] Furthermore, the acid added during acidification in step S2 is one of sulfuric acid and hydrochloric acid.
[0018] Step S2: The water phase in the oil-water separator is transferred to the acidification separator, acidified with acid, and the pH value is adjusted to 5.0-5.5, because a small amount of dibasic acid is still dissolved in the water phase and will not precipitate. At this time, the solid phase and the water phase are separated, and the solid phase is cyano acid, carboxylic acid amide and a very small amount of fatty diacid and other organic substances.
[0019] The purpose of vacuum dehydration in step S3 is: first, to remove the free water contained in the solid phase obtained in step S2; second, to promote the reaction of the amide group in the carboxyamide to remove water and generate cyano group, thereby obtaining the product cyano acid.
[0020] Furthermore, in step S3, the dehydrating agent is phosphorus pentoxide, and the added amount is 8-14% of the mass of the fatty diacid.
[0021] Phosphorus pentoxide is used as a dehydrating agent in step S3 to promote the amide group in the carboxyamide to react and remove water to generate cyano group, thereby accelerating the reaction process.
[0022] In step S3, the vacuum dehydration stirring speed is 60-150 r / min, and the temperature during vacuum dehydration is 210-230° C. If it is lower than 210° C., the dehydration speed slows down; if it is higher than 230° C., the system will obviously carry over the material.
[0023] The technical solution provided by the embodiment of the present invention has the following beneficial effects: 1. By adopting the process technology of the present invention, only the amination process parameters need to be adjusted, and cyanic acid products can be co-produced while producing dinitriles.
[0024] 2. During specific production, the ratio of the two products can be flexibly adjusted, but the total yield remains unchanged.
[0025] 3. Without changing the original ammonia unit, the investment cost can be greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 It is a flowchart of the process route for co-producing long-chain cyanic acid in an embodiment of the present invention.
[0027] Figure 2 It is a process flow chart of the semi-amination reaction in the embodiment of the present invention.
[0028] Explanation of the reference numerals: 1- ammonia pressure stabilizing bag; 2- ammonia flow meter; 3- ammonia reactor; 4- condenser; 5- oil-water separator. DETAILED DESCRIPTION
[0029] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "inside, outside", "up, down", "left, right", "in, out", etc. are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention.
[0030] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0031] Example 1 like Figure 1 As shown, a method for co-producing long-chain cyanic acid comprises the following steps: Step S1, semi-ammoniation reaction: 3 kg of sebacic acid and 90 g of catalyst (40-100 mesh silica gel) were added to the ammoniation reactor 3, replaced with nitrogen, and the electric heating device of the ammoniation reactor 3 was turned on to heat the melting temperature to 195°C. The valve of the ammonia pressure stabilizing bag 1 was opened to introduce ammonia gas to react and rise to 220°C. The ammonia flowmeter 2 was adjusted so that the flow rate of ammonia gas was 120 dm 3 / h, the pressure of the ammonia buffer bag 1 is 0.25MPa, the stirring speed of the ammoniation reactor 3 is 80r / min, the temperature continues to rise to 240°C for reaction for 2.5h, and then the temperature is raised to 280°C for reaction for 7h. During the reaction, the vapor phase is condensed by the condenser 4 and the condensate is collected in the oil-water separator 5, the upper layer is the oil phase, and the lower layer is the water phase. The oil phase is dynamically refluxed to the ammoniation reactor 3 for further reaction, and the water phase is collected in the oil-water separator 5 to be separated in the next process; the ammoniation reactor 3 contains the crude product of sebacate; Step S2, acidification and separation: After the semi-ammoniation reaction is completed, the aqueous phase obtained in step S1 is transferred to an acidification separator, and sulfuric acid is added to neutralize the mixture under stirring, and the pH value is adjusted to 5.1. The mixture is filtered and separated, and the solid is washed to obtain 1.28 kg of solid.
[0032] Step S3, vacuum dehydration: the solid obtained in step S2 is placed in a vacuum dehydration kettle, 30 g of dehydrating agent phosphorus pentoxide is added, stirred, the speed is 60 r / min, the vacuum is turned on, heated to 225°C, reacted for 2.5 hours, and 1.08 kg of crude cyanic acid is obtained.
[0033] The sample was derivatized and the content of 9-cyanononanoic acid was 91.40% determined by gas chromatography.
[0034] The content of sebacinonitrile in the amination reactor 3 was 1.45 kg and was determined by gas chromatography to be 95.1%.
[0035] Example 2 A method for co-producing long-chain cyanic acid comprises the following steps: Step S1, semi-ammoniation reaction: 3 kg of dodecanedioic acid and 90 g of catalyst (40-100 mesh silica gel) were added to the ammoniation reactor 3, nitrogen was replaced, the electric heating was turned on, the melting temperature was heated to 195°C, the valve of the ammonia pressure regulating bag 1 was opened, ammonia was introduced for reaction and the temperature was raised to 220°C, and the ammonia flowmeter 2 was adjusted so that the flow rate of ammonia was 120 dm3 / h, the pressure of the ammonia buffer bag 1 is 0.25MPa, the stirring speed of the ammonia reactor 3 is 80r / min, the temperature is raised to 240℃ for reaction for 2.5h, and then the temperature is raised to 280℃ for reaction for 7h. During the reaction, the vapor phase is condensed by the condenser 4 and the condensate is collected in the oil-water separator 5, the upper layer is the oil phase, and the lower layer is the water phase. The oil phase is dynamically refluxed to the ammonia reactor 3 to continue the reaction, and the water phase is collected in the oil-water separator 5 to be separated in the next step; the ammonia reactor 3 contains the crude dodecanedinitrile.
[0036] Step S2, acidification and separation: After the semi-ammoniation reaction is completed, the aqueous phase obtained in step S1 is transferred to an acidification separator, and sulfuric acid is added to neutralize the mixture under stirring, and the pH value is adjusted to 5.1. The mixture is filtered and separated, and the solid is washed to obtain 1.12 kg of solid.
[0037] Step S3, vacuum dehydration: the solid obtained in step S2 is placed in a vacuum dehydration reactor, 30 g of dehydrating agent phosphorus pentoxide is added, the stirring speed is 60 r / min, the vacuum is turned on, the temperature is heated to 225° C., and the reaction is carried out for 2.5 h to obtain 0.95 kg of crude cyanic acid.
[0038] After the sample was derivatized and analyzed by gas chromatography, the content of 11-cyanoundecanoic acid was 90.2%.
[0039] The amount of dodecanedinitrile in the amination reactor 3 was 1.61 kg, and the content was 89.3% as determined by gas chromatography.
[0040] Example 3 A method for co-producing long-chain cyanic acid comprises the following steps: Step S1, semi-ammoniation reaction: 3 kg of undecanedioic acid and 90 g of catalyst (40-100 mesh silica gel) were added to the ammoniation reactor 3, nitrogen replacement was performed, electric heating was turned on, the melting temperature was heated to 195°C, the valve of the ammonia pressure regulating bag 1 was opened, ammonia was introduced for reaction and the temperature was raised to 220°C, and the ammonia flowmeter 2 was adjusted so that the flow rate of ammonia was 120 dm 3 / h, the pressure of the ammonia buffer bag 1 is 0.25MPa, the stirring speed of the ammonia reactor 3 is 80r / min, the temperature is raised to 240℃ for reaction for 2.5h, and then the temperature is raised to 280℃ for reaction for 7h. During the reaction, the vapor phase is condensed by the condenser 4 and the condensate is collected in the oil-water separator 5, the upper layer is the oil phase, and the lower layer is the water phase. The oil phase is dynamically refluxed to the ammonia reactor 3 to continue the reaction, and the water phase is collected in the oil-water separator 5 to be separated in the next step; the ammonia reactor 3 contains the crude undecane dinitrile.
[0041] Step S2, acidification and separation: After the semi-ammoniation reaction is completed, the aqueous phase obtained in step S1 is transferred to an acidification separator, and sulfuric acid is added to neutralize the mixture under stirring, and the pH value is adjusted to 5.1. The mixture is filtered and separated, and the solid is washed to obtain 1.32 kg of solid.
[0042] Step S3, vacuum dehydration: the solid obtained in step S2 is placed in a vacuum dehydration kettle, 30 g of dehydrating agent phosphorus pentoxide is added, stirred, the speed is 60 r / min, the vacuum is turned on, heated to 225°C, reacted for 2.5 hours, and 1.17 kg of crude cyanic acid is obtained.
[0043] The sample was derivatized and the content of 10-cyanodecanoic acid was determined by gas chromatography to be 92.1%.
[0044] The content of undecane dinitrile in the amination reactor 3 was 1.39 kg and was determined by gas chromatography to be 93.2%.
[0045] Example 4 A method for co-producing long-chain cyanic acid comprises the following steps: Step S1, semi-ammoniation reaction: 3 kg of azelaic acid and 85 g of catalyst (40-100 mesh silica gel) are added to the ammoniation reactor 3, nitrogen replacement, electric heating is turned on, heating and melting, the temperature is raised to 195 ° C, the valve of the ammonia pressure regulating bag 1 is opened, ammonia is introduced to react and the temperature is raised to 220 ° C, and the ammonia flowmeter 2 is adjusted so that the flow rate of ammonia is 120 dm 3 / h, the pressure of the ammonia buffer bag 1 is 0.25MPa, the stirring speed of the ammonia reactor 3 is 80r / min, the temperature is raised to 240℃ for reaction for 2.5h, and then the temperature is raised to 280℃ for reaction for 7h; During the reaction, the vapor phase is condensed by the condenser 4 and the condensate is collected in the oil-water separator 5. The upper layer is the oil phase and the lower layer is the water phase. The oil phase is dynamically refluxed to the amination reactor to continue the reaction, and the water phase is collected in the oil-water separator to be separated in the next step; the amination reactor contains the crude product of azelaic acid.
[0046] Step S2, acidification and separation: After the semi-ammoniation reaction is completed, the aqueous phase obtained in step S1 is transferred to an acidification separator, and sulfuric acid is added to neutralize the mixture under stirring, and the pH value is adjusted to 5.1. The mixture is filtered and separated, and the solid is washed to obtain 1.45 kg of solid.
[0047] Step S3, vacuum dehydration: the solid obtained in step S2 is placed in a vacuum dehydration reactor, 30 g of dehydrating agent phosphorus pentoxide is added, stirred at a speed of 60 r / min, vacuum is turned on, heated to 225° C., reacted for 2.5 h, and 1.26 kg of crude cyanic acid is obtained.
[0048] The sample was derivatized and the content of 8-cyanooctanoic acid was 90.5% determined by gas chromatography.
[0049] The content of 1.25 kg of azelaic acid in the amination reactor 3 was determined by gas chromatography to be 93.1%.
[0050] Comparative Example 1 A method for co-producing long-chain cyanic acid comprises the following steps: Step S1, semi-ammoniation reaction: 3 kg of sebacic acid and 90 g of catalyst (40-100 mesh silica gel) were added to the ammoniation reactor 3, nitrogen replacement was carried out, electric heating was turned on, the melting temperature was heated to 195°C, the valve of the ammonia pressure regulating bag 1 was opened, ammonia was introduced, and the ammonia flowmeter 2 was adjusted so that the flow rate of ammonia was 120 dm 3 / h, the pressure of the ammonia buffer bag 1 is 0.25MPa, the stirring speed of the ammonia reactor 3 is 80r / min, the temperature is raised to 220℃ and reacted for 2.5h, and then the temperature is maintained at 280℃ and reacted for 7h; During the reaction, the vapor phase is condensed by the condenser 4 and the condensate is collected in the oil-water separator 5. The upper layer is the oil phase and the lower layer is the water phase. The oil phase is dynamically refluxed to the ammoniation reactor 3 to continue the reaction, and the water phase is collected in the oil-water separator 5 to be separated in the next step; the ammoniation reactor 3 contains the crude product of sebaconinitrile.
[0051] Step S2, acidification and separation: After the semi-ammoniation reaction is completed, the aqueous phase obtained in step S1 is transferred to an acidification separator, and sulfuric acid is added to neutralize the mixture under stirring, and the pH value is adjusted to 5.1. The mixture is filtered and separated, and the solid is washed to obtain 1.28 kg of solid.
[0052] Step S3, vacuum dehydration: the solid obtained in step S2 is placed in a vacuum dehydration kettle, 30 g of dehydrating agent phosphorus pentoxide is added, stirred, the speed is 60 r / min, the vacuum is turned on, heated to 225°C, reacted for 2.5 hours, and 0.91 kg of crude cyanic acid is obtained.
[0053] The sample was derivatized and the content of 9-cyanononanoic acid was 90.8% determined by gas chromatography.
[0054] There are 1.32 kg of sebacinonitrile in the amination reactor 3, and the content is 82.3% as determined by gas chromatography.
[0055] Comparative Example 2 A method for co-producing long-chain cyanic acid comprises the following steps: Step S1, semi-ammoniation reaction: 3 kg of sebacic acid and 90 g of catalyst (40-100 mesh silica gel) were added to the ammoniation reactor 3, nitrogen was replaced, the electric heating was turned on, the melting temperature was heated to 195°C, the valve of the ammonia pressure regulating bag 1 was opened, ammonia was introduced to react and the temperature was raised to 220°C, and the ammonia flowmeter 2 was adjusted so that the flow rate of ammonia was 120 dm 3 / h, the pressure of the ammonia buffer bag 1 is 0.25MPa, the stirring speed of the ammonia reactor 3 is 80r / min, the temperature is raised to 240℃ for reaction for 2.5h, and then the temperature is raised to 260℃ for reaction for 7h; During the reaction, the vapor phase is condensed by the condenser 4 and the condensate is collected in the oil-water separator 5. The upper layer is the oil phase and the lower layer is the water phase. The oil phase is dynamically refluxed to the ammoniation reactor 3 to continue the reaction, and the water phase is collected in the oil-water separator 5 to be separated in the next step; the ammoniation reactor 3 contains the crude product of sebaconinitrile.
[0056] Step S2, acidification and separation: After the semi-ammoniation reaction is completed, the aqueous phase obtained in step S1 is transferred to an acidification separator, and sulfuric acid is added to neutralize the mixture under stirring, and the pH value is adjusted to 5.1. The mixture is filtered and separated, and the solid is washed to obtain 1.28 kg of solid.
[0057] Step S3, vacuum dehydration: the solid obtained in step S2 is placed in a vacuum dehydration kettle, 30 g of dehydrating agent phosphorus pentoxide is added, stirred, the speed is 60 r / min, the vacuum is turned on, heated to 225°C, reacted for 2.5 hours, and 0.78 kg of crude cyanic acid is obtained.
[0058] The sample was derivatized and the content of 9-cyanononanoic acid was determined by gas chromatography to be 88.4%.
[0059] The content of 1.1 kg of sebacinonitrile in the amination reactor 3 was determined by gas chromatography to be 89.1%.
[0060] Comparative Example 3 (Comparative to Example 1, no catalyst was added to the semi-amination reaction, and other conditions remained unchanged) A method for co-producing long-chain cyanic acid comprises the following steps: Step S1, semi-ammoniation reaction: 3 kg of sebacic acid was added to the ammoniation reactor 3, nitrogen was replaced, the electric heating was turned on, the melting temperature was heated to 195°C, the valve of the ammonia pressure regulating bag 1 was opened, ammonia was introduced to react and the temperature was raised to 220°C, and the ammonia flowmeter 2 was adjusted so that the flow rate of ammonia was 120 dm 3 / h, the pressure of the ammonia buffer bag 1 is 0.25MPa, the stirring speed of the ammonia reactor 3 is 80r / min, the temperature is raised to 240℃ for reaction for 2.5h, and then the temperature is raised to 280℃ for reaction for 7h; During the reaction, the vapor phase is condensed by the condenser 4 and the condensate is collected in the oil-water separator 5. The upper layer is the oil phase and the lower layer is the water phase. The oil phase is dynamically refluxed to the ammoniation reactor 3 to continue the reaction, and the water phase is collected in the oil-water separator 5 to be separated in the next step; the ammoniation reactor 3 contains the crude product of sebaconinitrile.
[0061] Step S2, acidification and separation: After the semi-ammoniation reaction is completed, the aqueous phase obtained in step S1 is transferred to an acidification separator, and sulfuric acid is added to neutralize the mixture under stirring, and the pH value is adjusted to 5.1. The mixture is filtered and separated, and the solid is washed to obtain 1.35 kg of solid.
[0062] Step S3, vacuum dehydration: the solid obtained in step S2 is placed in a vacuum dehydration kettle, 30 g of dehydrating agent phosphorus pentoxide is added, stirred, the speed is 60 r / min, the vacuum is turned on, heated to 225°C, reacted for 2.5 hours, and 1.24 kg of crude cyanic acid is obtained.
[0063] The sample was derivatized and determined by gas chromatography, and the content of 9-cyanononanoic acid was 54.0%.
[0064] There are 1.35 kg of sebacinonitrile in the amination reactor 3, and the content is 72.3% as determined by gas chromatography.
[0065] Comparative Example 4 A method for co-producing long-chain cyanic acid comprises the following steps: Step S1, semi-ammoniation reaction: 3 kg of sebacic acid and 90 g of catalyst (40-100 mesh silica gel) were added to the ammoniation reactor 3, nitrogen was replaced, the electric heating was turned on, the melting temperature was heated to 195°C, the valve of the ammonia pressure regulating bag 1 was opened, ammonia was introduced to react and the temperature was raised to 220°C, and the ammonia flowmeter 2 was adjusted so that the flow rate of ammonia was 120 dm 3 / h, the pressure of the ammonia buffer bag 1 is 0.25MPa, the stirring speed of the ammonia reactor 3 is 80r / min, the temperature is raised to 240℃ for reaction for 2.5h, and then the temperature is raised to 280℃ for reaction for 7h; During the reaction, the vapor phase is condensed by the condenser 4 and the condensate is collected in the oil-water separator 5. The upper layer is the oil phase and the lower layer is the water phase. The oil phase is dynamically refluxed to the ammoniation reactor 3 to continue the reaction, and the water phase is collected in the oil-water separator 5 to be separated in the next step; the ammoniation reactor 3 contains the crude product of sebaconinitrile.
[0066] Step S2, acidification and separation: After the semi-ammoniation reaction is completed, the aqueous phase obtained in step S1 is transferred to an acidification separator, and sulfuric acid is added to neutralize the mixture under stirring, and the pH value is adjusted to 5.1. The mixture is filtered and separated, and the solid is washed to obtain 1.28 kg of solid.
[0067] Step S3, vacuum dehydration: place the solid obtained in step S2 in a vacuum dehydration kettle, stir, rotate at 60 r / min, open the vacuum, heat to 225° C., react for 2.5 h, and obtain 1.12 kg of crude cyanic acid.
[0068] The sample was derivatized and the content of 9-cyanononanoic acid was 86.30% determined by gas chromatography.
[0069] The content of sebacinonitrile in the amination reactor 3 was 1.45 kg and was determined by gas chromatography to be 95.1%.
[0070] like Figure 2As shown, the semi-ammoniation reaction device in Examples 1-4 and Comparative Examples 1-4 includes: an ammonia pressure stabilizing bag 1, an ammonia flowmeter 2, an ammoniation reactor 3, a condenser 4, and an oil-water separator 5; The inlet end of the ammonia reactor 3 is connected to the gas outlet end of the ammonia pressure stabilizing bag 1, an ammonia flowmeter 2 is arranged between the ammonia pressure stabilizing bag 1 and the ammonia reactor 3, the outlet end of the ammonia reactor 3 is connected to the inlet end of the condenser 4, the outlet end of the condenser 4 is connected to the inlet end of the oil-water separator 5, the outlet end of the oil-water separator 5 is connected to the inlet end of the ammonia reactor 3, and the ammonia reactor 3 is provided with an electric heating device and a stirring device.
[0071] It can be seen from the above Examples 1-4 and Comparative Examples 1-4 that: by adopting the method for co-producing cyanic acid of the present invention, a set of equipment can produce two products, and the total yield of the two products: dinitrile and cyanic acid is stable and of good quality.
[0072] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.
Claims
1. A method for co-producing long-chain cyanic acid, characterized in that: The following steps are involved: Step S1, semi-ammoniation reaction: a fatty diacid and a catalyst are put into an ammoniation reactor, nitrogen replaces oxygen in the ammoniation reactor, heats and melts to 190-195° C., introduces ammonia to react and heats to 215-225° C., continues to heat to 237-243° C. for 2-3 hours, then heats to 270-290° C., reacts for 6-8 hours and ends, during the reaction, the vapor phase condensate is collected in an oil-water separator, the upper layer is an oil phase, the lower layer is an aqueous phase, the oil phase is dynamically refluxed to the ammoniation reactor to continue the reaction, the aqueous phase is collected in the oil-water separator, and is separated in the next step; the amoniation reactor contains a crude fatty dinitrile; Step S2, acidification separation: after the semi-ammoniation reaction is completed, the water phase in the oil-water separator is transferred to an acidification separator, acidified to pH=5.0-5.5 by adding acid, and the solid is separated; Step S3, vacuum dehydration: the solid obtained in step S2 is placed in a vacuum dehydration reactor, a dehydrating agent is added, vacuumized and heated to melt, the temperature is raised to 220-230° C. with stirring, and dehydrated for 2-3 hours to obtain a cyanic acid product.
2. The method for co-producing long-chain cyanic acid according to claim 1, characterized in that: In step S1, the flow rate of ammonia gas is 30-60 dm / kg fatty acid. 3 / h, the pressure of the ammonia buffer bag is 0.2-0.3MPa, and the stirring speed of the ammonia reactor is 60-90r / min.
3. The method for co-producing long-chain cyanic acid according to claim 1, characterized in that: In step S1, the inlet end of the ammonia reactor is connected to the gas outlet end of the ammonia pressure stabilizing bag, an ammonia flowmeter is arranged between the ammonia pressure stabilizing bag and the ammonia reactor, the outlet end of the ammonia reactor is connected to the inlet end of the condenser, the outlet end of the condenser is connected to the inlet end of the oil-water separator, the outlet end of the oil-water separator is connected to the inlet end of the ammonia reactor, and the ammonia reactor is provided with an electric heating device and a stirring device.
4. The method for co-producing long-chain cyanic acid according to claim 1, characterized in that: In step S1, the fatty diacid is a dibasic acid with a carbon chain of C9-C12, and is one of azelaic acid, sebacic acid, undecanedioic acid and dodecanedioic acid.
5. The method for co-producing long-chain cyanic acid according to claim 2, characterized in that: In step S1, the catalyst is an oxide containing zinc or aluminum or a metal salt containing a molybdenum component, or is silica gel, and the added amount is 2.5% to 5% of the mass of the fatty diacid.
6. The method for co-producing long-chain cyanic acid according to claim 1, characterized in that: In step S2, the acid added during acidification is one of sulfuric acid and hydrochloric acid.
7. The method for co-producing long-chain cyano acid according to claim 1, characterized in that: In step S3, the dehydrating agent is phosphorus pentoxide, and the added amount is 8-14% of the mass of the fatty diacid.
Citation Information
Patent Citations
Preparation method of long-carbon-chain cyano acid
CN107325022A