CN113444018A - Method for producing adiponitrile - Google Patents

Method for producing adiponitrile Download PDF

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CN113444018A
CN113444018A CN202110716184.1A CN202110716184A CN113444018A CN 113444018 A CN113444018 A CN 113444018A CN 202110716184 A CN202110716184 A CN 202110716184A CN 113444018 A CN113444018 A CN 113444018A
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hydrocyanation
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CN113444018B (en
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康小玲
丁永良
郑伯川
郑晨
邹志刚
张飞
钟显威
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Shanghai Donggeng Chemical Technology Co ltd
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    • C—CHEMISTRY; METALLURGY
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    • C07C253/00—Preparation of carboxylic acid nitriles
    • C07C253/08—Preparation of carboxylic acid nitriles by addition of hydrogen cyanide or salts thereof to unsaturated compounds
    • C07C253/10—Preparation of carboxylic acid nitriles by addition of hydrogen cyanide or salts thereof to unsaturated compounds to compounds containing carbon-to-carbon double bonds
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C253/00—Preparation of carboxylic acid nitriles
    • C07C253/30—Preparation of carboxylic acid nitriles by reactions not involving the formation of cyano groups
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Abstract

The invention discloses a method for producing adiponitrile, which comprises the following steps: (1) mixing 1, 3-butadiene, hydrocyanic acid, a catalyst and a ligand, then sequentially carrying out primary hydrocyanation in a large-channel reactor and a DSR reactor, removing 1, 3-butadiene and most unreacted hydrocyanic acid from a material obtained after the primary hydrocyanation through adiabatic flash evaporation, removing residual hydrocyanic acid through a stripping tower, then entering a separation tower, extracting 2-methyl-3-butenenitrile from the top of the tower, and extracting 3-pentenenitrile from the side line in the tower; (2) adding Lewis acid and a catalyst into a 2-methyl-3-butenenitrile solution from primary hydrocyanation, and isomerizing to obtain 3-pentenenitrile; (3) and (3) carrying out secondary hydrocyanation on the 3-pentenenitrile obtained in the step (1), the material obtained in the step (2) and hydrocyanic acid to generate adiponitrile. The method can reduce the loss of products and raw materials and the risk of catalyst poisoning, is a high-efficiency, environment-friendly, high-yield and economic adiponitrile synthesis method, and is suitable for industrial production.

Description

Method for producing adiponitrile
Technical Field
The invention relates to the technical field of organic synthesis, in particular to a method for producing adiponitrile.
Background
Adiponitrile (adisonile, ADN for short) is a colorless to pale yellow transparent liquid, slightly odorous, slightly soluble in water, ether and alcohol, and is one of the essential main raw materials for producing nylon 66. The adiponitrile is hydrogenated and reduced to obtain the hexamethylene diamine, and the hexamethylene diamine and adipic acid are polycondensed to obtain the nylon 66. Adiponitrile can also be used for preparing chemical products such as caprolactam and the like, can also be used in textile industry and electroplating industry, and has wide application in the field of chemical industry.
The existing process routes for producing adiponitrile mainly include an acrylonitrile electrolysis method, a butadiene hydrocyanation method, an adipic acid catalytic ammoniation method and the like. The butadiene hydrocyanation process is classified into a butadiene hydrocyanation chloride process and a butadiene direct hydrocyanation process. The hydrocyanation method of butadiene chloride is a method developed by DuPont in the early 60 th of the 20 th century, and the method has the defects of complex process, serious corrosion, large investment, consumption of a large amount of chlorine and hydrocyanic acid and is eliminated. In the early 70 s, DuPont developed a direct hydrocyanation method for butadiene without using chlorine, which avoids the pollution problem caused by electrolyzing and removing sodium chloride in a chlorination-cyanidation method, reduces the raw material cost by 15% compared with the chlorination method, and saves energy by 45%. The direct butadiene cyanidation method is the most mainstream adiponitrile production process route at present, has the characteristics of wide raw material, short process route, higher yield, less pollution and the like, is called as a process showing green competitiveness, and is the most reasonable adiponitrile preparation method with the best atom economy at present.
Reaction principle of direct hydrocyanation of butadiene: the reaction for producing adiponitrile by direct hydrocyanation of butadiene comprises three steps of primary cyanidation, isomerization and secondary cyanidation, and the method adopts a transition metal catalyst to introduce two molecules of HCN into butadiene, wherein the catalyst generally adopts a complex of transition metals such as Ni, Rh, Ru and the like.
For example: patent document CN103180290A discloses a method for preparing nitrile, which discloses a butadiene method for synthesizing adiponitrile by mainly three steps of primary hydrocyanation, isomerization and secondary hydrocyanation, wherein the reaction equations of the three steps are as follows:
(1) primary hydrocyanation
Figure BDA0003134188640000011
(2) Isomerization of
Figure BDA0003134188640000012
(3) Secondary hydrocyanation
Figure BDA0003134188640000021
The patent publication No. CN103012197A also discloses a method for preparing 3-pentenenitrile and a method for preparing adiponitrile, wherein the method for synthesizing adiponitrile by butadiene mainly comprises two steps of hydrocyanation and secondary hydrocyanation, and the reaction equations of the two steps are as follows:
Figure BDA0003134188640000022
however, both of the two-step butadiene synthesis and the three-step butadiene synthesis of adiponitrile have the following problems: (1) after the primary hydrocyanation reaction, respectively recovering butadiene, hydrocyanic acid and a nickel catalyst, separating and purifying the 3-pentenenitrile, and then carrying out secondary hydrocyanation reaction on the 3-pentenenitrile and the hydrocyanic acid to obtain a crude product of adiponitrile. The conversion rate of the primary hydrocyanation reaction is 70 to 72 percent, the selectivity is 72 to 75 percent, the conversion rate of the secondary hydrocyanation reaction is 70 to 72 percent, and the selectivity is 75 to 80 percent; (2) the reaction is carried out in a conventional pressure kettle, the multiphase reaction materials are poor in mixing, the reaction time is long, and the yield and the selectivity are low; (3) multiple times of rectification are needed to cause material polymerization and catalyst decomposition, so that the production cost is greatly improved.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, the present invention aims to provide a method for producing adiponitrile, which simplifies the process flow, improves the product yield, reduces the equipment cost and production cost, and reduces the loss of products and raw materials and the risk of catalyst poisoning.
To achieve the above and other related objects, the present invention provides a method for producing adiponitrile, comprising the steps of:
(1) primary hydrocyanation: mixing 1, 3-Butadiene (BD), hydrocyanic acid (HCN), a catalyst and a ligand, then sequentially carrying out primary hydrocyanation in a large-channel reactor and a DSR reactor, removing 1, 3-butadiene and most of unreacted hydrocyanic acid from materials obtained after the primary hydrocyanation through adiabatic flash evaporation, removing residual hydrocyanic acid from the flashed materials through a stripping tower, feeding tower bottom materials passing through the stripping tower into a separation tower, collecting materials mainly comprising 2-methyl-3-butenenitrile (2M3BN) from the top of the separation tower, collecting the 2-methyl-2-butenenitrile (2M2BN) and 2-pentenenitrile (2PN) from the side line of the tower, and mechanically applying the tower bottom ligand and the catalyst to the primary hydrocyanation;
(2) isomerization: mixing a 2-methyl-3-butenenitrile (2M3BN) solution from primary hydrocyanation with Lewis acid, filtering to remove undissolved Lewis acid after saturation, sequentially conveying the filtrate and a catalyst in proportion through a large channel reactor and a DSR reactor, and carrying out isomerization treatment (namely, reacting in the large channel reactor and then in the DSR reactor) on the 2-methyl-3-butenenitrile (2M3BN) to convert the 2-methyl-3-butenenitrile (2M3BN) into 3-pentenenitrile (3-PN);
(3) secondary hydrocyanation: sequentially conveying the 3-pentenenitrile (3-PN) from the step (1), the isomerized material from the step (2), hydrocyanic acid and a catalyst in proportion through a large channel reactor and a DSR reactor to carry out secondary hydrocyanation, and reacting to generate adiponitrile (the large channel reactor firstly reacts in the large channel reactor and then reacts in the DSR reactor); wherein the feed from the isomerization in step (2) contains 3-pentenenitrile and a quantity of catalyst.
Further, in the step (1), the reaction conditions of the large-channel reactor and the DSR reactor are controlled to be the same, the pressure is controlled to be 1.0-1.5 Mpa, and the reaction temperature of primary hydrocyanation is controlled to be 90-100 ℃.
Further, in the step (1), the flash evaporation temperature is controlled to be 90-110 ℃, the flash evaporation pressure is 60-160 kpa, and the total content of hydrocyanic acid and 1, 3-Butadiene (BD) is controlled to be below 2 wt% (mass fraction).
Further, in the step (1), when the residual hydrocyanic acid is removed through the stripping tower, the operation pressure is 1.5-2 bar, the tower top temperature is 8-15 ℃, and the tower kettle temperature is 120-140 ℃.
Further, in the step (1), the temperature of the top of the separation tower is controlled to be 35-65 ℃, the pressure is controlled to be 1-10 kpa, and the temperature of the bottom of the separation tower is controlled to be 105-130 ℃.
Further, in the step (1), the molar ratio of the 1, 3-butadiene, the hydrocyanic acid, the catalyst and the ligand is 100-500: 90-400: 1: 20-100.
Further, in the step (2), when the 2-methyl-3-butenenitrile (2M3BN) solution from the primary hydrocyanation is mixed with the Lewis acid, the temperature is controlled to be 60-100 ℃.
Further, in the step (2), the Lewis acid is selected from ZnCl2、ZnBr2、ZnI2、AlCl3、SnCl4、TiCl3And Triphenylboron (TPB). The Lewis acid is used for improving the catalytic activity of the catalyst, thereby improving the reaction speed and modulating the reaction selectivity.
Further, in the step (2), the dosage of the Lewis acid is 0.01-0.2 mol equivalent of 2-methyl-3-butenenitrile, and the dosage of the catalyst is 0.01-0.02 mol equivalent of 2-methyl-3-butenenitrile; the molar ratio of the Lewis acid to the catalyst is 1: 4-6, preferably 1: 5.
Further, in the step (2), the reaction temperature of the materials in the large channel reactor and the DSR reactor is controlled to be 100-145 ℃, and the reaction pressure is controlled to be 0.3-0.8 MPa; preferably, the reaction temperature is controlled to be 110-130 ℃. The reaction temperature is controlled to be near the boiling point of 2-methyl-3-butenenitrile (2M3BN), the catalytic activity is highest, the reaction speed is faster, and the selectivity is higher.
Furthermore, in the step (2), after the isomerization treatment is finished, impurities need to be separated, and the separation method is selected from one of the following two modes:
A. conveying the material after the isomerization reaction to the top of an isomerization tower, separating a small amount of organic impurities, wherein the temperature of a tower kettle is 115-125 ℃, and the pressure is-0.06 MPa-0.08 MPa;
B. and (3) carrying out low-temperature crystallization separation on the material after the isomerization reaction is finished, controlling the temperature to be 20-70 ℃ and the pressure to be normal pressure, and separating out a small amount of organic impurities.
Wherein the organic impurities comprise 2-methyl-3-butenenitrile (2M3BN), 2-pentenenitrile (2-PN), and the like; the isomerization tower is a packed tower.
Further, in the step (3), during the secondary hydrocyanation, the mole ratio of the catalyst, hydrocyanic acid (HCN) and 3-pentenenitrile (2-PN) is 1: 40-60: 60-70.
Further, in the step (3), during secondary hydrocyanation, the reaction temperature is controlled to be 60-90 ℃, and the pressure is controlled to be 0.4-0.8 Mpa.
Further, the method further comprises the step (4): and (3) separating the material after the secondary hydrocyanation reaction is finished by a rectification mode to obtain Adiponitrile (ADN) and 2-methylglutaronitrile (2-MGN), and recovering the catalyst and unreacted hydrocyanic acid and 3-pentenenitrile.
Further, in the step (4), the material after the secondary hydrocyanation reaction is firstly rectified to sequentially recover unreacted hydrocyanic acid AND 3-pentenenitrile, the remaining material is then extracted to separate out the catalyst, ammonia gas is introduced into the raffinate phase to perform reaction, the material is centrifuged AND filtered after the reaction is finished, the obtained filtrate is subjected to negative pressure rectification after excessive ammonia is removed, a light component is separated from the top of the tower at one time, the light component comprises an extracting agent, 3-pentenenitrile AND m-cresol, a mixture of Adiponitrile (ADN) AND 2-methylglutaronitrile (2-MGN/AND) is extracted from the side line (namely a 2-MGN/AND mixture), AND then the Adiponitrile (ADN) product is obtained through rectification separation.
Optionally, in the step (4), the operation pressure of the hydrocyanic acid (HCN) recovery tower is less than or equal to 90kpa, the tower top temperature is 8-10 ℃, and the tower kettle temperature is 120-135 ℃, so as to control the concentration of the hydrocyanic acid (HCN) in the tower kettle to be less than 0.01%.
Optionally, in the step (4), the operation pressure of the tower for recovering the 3-pentenenitrile is less than or equal to 2kpa, the tower top temperature is 30-50 ℃, the tower bottom temperature is 105-125 ℃, and the preferable temperature is 110-115 ℃. The reaction conditions in the recovery of 3-pentenenitrile are controlled within the above-mentioned range in order to reduce the formation of by-products while satisfying the separation requirements.
Optionally, in the step (4), during extraction, the temperature is 50-65 ℃, the extractant is selected from at least one of cyclohexane, cyclopentane, n-hexane, n-pentane and n-heptane, and the extractant is similar in polarity to the ligand and the catalyst and can be dissolved mutually without being dissolved mutually with 2-methylglutaronitrile and adiponitrile, so that the extraction separation effect is effectively achieved.
Optionally, in the step (4), after extraction, the extractant is recovered from the extraction phase through the top of the rectification tower, the temperature of the top of the rectification tower is 10-25 ℃, the pressure is 5-8 Kpa, the catalyst is recovered from the bottom of the rectification tower, the temperature is 110-135 ℃, and the pressure is 6-10 Kpa. Under the condition, the separation effect can be effectively achieved, and meanwhile, the catalyst is recovered within the temperature range of 110-135 ℃, so that the catalyst can be kept within a better activity range.
Optionally, in the step (4), ammonia gas is introduced into the raffinate phase for reaction, the reaction temperature is 45-55 ℃, and the reaction time is 30-120 min, so that the lewis acid in the raffinate phase is completely separated out.
Optionally, in the step (4), when the light components are separated from the top of the tower at one time by the negative pressure rectification, the temperature of the top of the tower is 40-50 ℃, the temperature of the bottom of the tower is 160-185 ℃, and the pressure of the bottom of the tower is 0.5-2 Kpa, preferably 0.5-1.5 Kpa. Under the operating conditions, the content of light components in the tower kettle can be effectively controlled to be less than 0.5 percent, the amount of Adiponitrile (AND) in the tower kettle is controlled to be less than 1 percent, the generation of heavy boiling products is reduced, AND the purity of ADN products separated in a product rectifying tower in the subsequent process is favorably improved.
Optionally, in the step (4), the mixture of adiponitrile and 2-methylglutaronitrile is separated by a rectifying tower, 2-methylglutaronitrile is extracted from the top of the tower, the temperature of the top of the tower is 150-160 ℃, adiponitrile is extracted from the middle part of the tower, the temperature is 165-170 ℃, and the recovery rate (i.e. yield) of adiponitrile is larger than 95%.
Further, in the steps (1) to (4), the catalyst is composed of nickel and triaryl phosphite.
Further, in the step (1), the ligand is at least one selected from the group consisting of triphenyl phosphite, tri-m-tolyl phosphite, tri-p-tolyl phosphite, and tri-o-tolyl phosphite.
As described above, the method for producing adiponitrile according to the present invention has the following advantageous effects:
because the primary hydrocyanation and the secondary hydrocyanation are strongly exothermic homogeneous reactions, in order to ensure the heat transfer and heat transfer effects of the reaction, reduce the reaction time and reduce the occurrence of side reactions, the invention selects a large-channel reactor and a DSR reactor as the reactors.
The method simplifies the production process flow of adiponitrile, can improve the yield efficiency, reduce the equipment cost and the production cost, reduce the loss of products and raw materials and the risk of catalyst poisoning, is an adiponitrile synthesis method with high efficiency, environmental protection, high yield and better economy, and is suitable for industrial production.
Drawings
FIG. 1 is a schematic view of a primary hydrocyanation and recovery process in the adiponitrile production process of the present invention.
FIG. 2 is a schematic diagram of the isomerization and separation process in the adiponitrile production process of the present invention.
FIG. 3 is a schematic diagram of the flow of secondary hydrocyanation and catalyst recovery in the adiponitrile production process of the present invention.
FIG. 4 is a schematic diagram of the rectification process flow of amino products in the adiponitrile production method of the invention.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
As shown in fig. 1, 2, 3 and 4, the present invention provides a method for producing adiponitrile, comprising the steps of:
(1) primary hydrocyanation: mixing 1, 3-Butadiene (BD), hydrocyanic acid (HCN), a catalyst and a ligand, and then sequentially carrying out primary hydrocyanation in a large channel reactor and a DSR reactor, removing 1, 3-butadiene and most of unreacted hydrocyanic acid from materials obtained after the primary hydrocyanation through adiabatic flash evaporation, and then recovering the 1, 3-butadiene and most of the unreacted hydrocyanic acid to the primary hydrocyanation for reuse; removing residual hydrocyanic acid from the flash-evaporated material through a stripping tower, and then recovering the hydrocyanic acid to primary hydrocyanation for reutilization; and (3) feeding the tower bottom material after passing through the stripping tower into a separation tower, extracting a material mainly comprising 2-methyl-3-butenenitrile (2M3BN) from the top of the separation tower, wherein the material also comprises 2-methyl-2-butenenitrile (2M2BN) and 2-pentenenitrile (2PN), extracting 3-pentenenitrile (3-PN) from the side line in the tower, and mechanically applying the tower bottom ligand and the catalyst to primary hydrocyanation.
(2) Isomerization: mixing a 2-methyl-3-butenenitrile (2M3BN) solution from primary hydrocyanation with Lewis acid, filtering to remove undissolved Lewis acid after saturation, recycling the Lewis acid, then conveying the filtrate and the catalyst in proportion in sequence through a large channel reactor and a DSR reactor, and carrying out isomerization treatment (reaction in the large channel reactor and then in the DSR reactor) on the 2-methyl-3-butenenitrile (2M3BN) to convert the 2-methyl-3-butenenitrile (2M3BN) into 3-pentenenitrile (3-PN).
(3) Secondary hydrocyanation: sequentially conveying the 3-pentenenitrile (3-PN) from the step (1), the isomerized material from the step (2), hydrocyanic acid and a catalyst in proportion through a large channel reactor and a DSR reactor, carrying out secondary hydrocyanation, and reacting to generate adiponitrile (namely, reacting in the large channel reactor first and then reacting in the DSR reactor); wherein the feed from the isomerization in step (2) contains 3-pentenenitrile and a quantity of catalyst.
Further, in the step (1), the reaction conditions of the large-channel reactor and the DSR reactor are controlled to be the same, the pressure is controlled to be 1.0-1.5 Mpa, and the reaction temperature of primary hydrocyanation is controlled to be 90-100 ℃.
Further, in the step (1), the flash evaporation temperature is controlled to be 90-110 ℃, the flash evaporation pressure is 60-160 kpa, and the total content of hydrocyanic acid and 1, 3-Butadiene (BD) is controlled to be less than 2 wt% (mass fraction).
Further, in the step (1), when the residual hydrocyanic acid is removed through the stripping tower, the operation pressure is 1.5-2 bar, the tower top temperature is 8-15 ℃, and the tower kettle temperature is 120-140 ℃.
Further, in the step (1), the temperature of the top of the separation tower is controlled to be 35-65 ℃, the pressure is controlled to be 1-10 kpa, and the temperature of the bottom of the separation tower is controlled to be 105-130 ℃.
Further, in the step (1), the molar ratio of the 1, 3-butadiene, the hydrocyanic acid, the catalyst and the ligand is 100-500: 90-400: 1: 20-100.
Further, in the step (2), when the 2-methyl-3-butenenitrile (2M3BN) solution from the primary hydrocyanation is mixed with the Lewis acid, the temperature is controlled to be 60-100 ℃.
Further, in the step (2), the Lewis acid is selected from ZnCl2、ZnBr2、ZnI2、AlCl3、SnCl4、TiCl3And Triphenylboron (TPB). The Lewis acid is used for improving the catalytic activity of the catalyst, thereby improving the reaction speed and modulating the reaction selectivity.
Further, in the step (2), the dosage of the Lewis acid is 0.01-0.2 mol equivalent of 2-methyl-3-butenenitrile, and the dosage of the catalyst is 0.01-0.02 mol equivalent of 2-methyl-3-butenenitrile; the molar ratio of the Lewis acid to the catalyst is 1: 4-6, preferably 1: 5.
Further, in the step (2), the reaction temperature of the materials in the large channel reactor and the DSR reactor is controlled to be 100-145 ℃, and the reaction pressure is controlled to be 0.3-0.8 MPa; preferably, the reaction temperature is controlled to be 110-130 ℃. The reaction temperature is controlled to be near the boiling point of 2-methyl-3-butenenitrile (2M3BN), the catalytic activity is highest, the reaction speed is faster, and the selectivity is higher.
In step (2), after the isomerization treatment is finished, impurities need to be separated, and the separation method is selected from one of the following two modes:
A. conveying the material after the isomerization reaction to the top of an isomerization tower, separating a small amount of organic impurities, wherein the temperature of a tower kettle is 115-125 ℃, and the pressure is-0.06 MPa-0.08 MPa;
B. and (3) carrying out low-temperature crystallization separation on the material after the isomerization reaction is finished, crystallizing in separate crystallization equipment, controlling the temperature to be 20-70 ℃, and separating a small amount of organic impurities under normal pressure.
Wherein the organic impurities comprise 2-methyl-3-butenenitrile (2M3BN), 2-pentenenitrile (2-PN), and the like, and the impurities are incinerated; the isomerization tower is a packed tower.
Further, in the step (3), during the secondary hydrocyanation, the mole ratio of the catalyst, hydrocyanic acid (HCN) and 3-pentenenitrile (2-PN) is 1: 40-60: 60-70.
Further, in the step (3), during secondary hydrocyanation, the reaction temperature is controlled to be 60-90 ℃, and the pressure is controlled to be 0.4-0.8 Mpa.
Further, the method further comprises the step (4): and separating the material after the secondary hydrocyanation reaction in a rectification mode to obtain Adiponitrile (ADN) and 2-methylglutaronitrile (2-MGN), and recovering the catalyst, unreacted hydrocyanic acid and 3-pentenenitrile to secondary hydrocyanation for reuse.
Further, in the step (4), the material after the secondary hydrocyanation reaction is rectified to sequentially recover unreacted hydrocyanic acid AND 3-pentenenitrile, the remaining material is extracted to separate out the catalyst, ammonia gas is introduced into raffinate phase (raffinate) for reaction, the material is centrifuged, filtered AND separated after the reaction is finished, the obtained filtrate is freed from excessive ammonia, negative pressure rectification is carried out, light components are separated from the top of the tower at one time, the light components comprise an extracting agent, 3-pentenenitrile AND m-cresol, a mixture (namely, a 2-MGN/AND mixture) of Adiponitrile (ADN) AND 2-methylglutaronitrile (2-MGN) is collected from the side line, AND then the Adiponitrile (ADN) product is obtained through rectification separation.
Optionally, in the step (4), the operation pressure of the hydrocyanic acid (HCN) recovery tower is less than or equal to 90kpa, the tower top temperature is 8-10 ℃, and the tower kettle temperature is 120-135 ℃, so as to control the concentration of the hydrocyanic acid (HCN) in the tower kettle to be less than 0.01%.
Optionally, in the step (4), the operation pressure of the tower for recovering the 3-pentenenitrile is less than or equal to 2kpa, the tower top temperature is 30-50 ℃, the tower bottom temperature is 105-125 ℃, and the preferable temperature is 110-115 ℃. The reaction conditions in the recovery of 3-pentenenitrile are controlled within the above-mentioned range in order to reduce the formation of by-products while satisfying the separation requirements.
Optionally, in the step (4), during extraction, the temperature is 50-65 ℃, the extractant is selected from at least one of cyclohexane, cyclopentane, n-hexane, n-pentane and n-heptane, and the extractant is similar in polarity to the ligand and the catalyst and can be dissolved mutually without being dissolved mutually with 2-methylglutaronitrile and adiponitrile, so that the extraction separation effect is effectively achieved. In the following examples, cyclohexane was used as the extractant, and other extractants listed in the present invention may be used.
Optionally, in the step (4), after extraction, the extractant is recovered from the extraction phase through the top of the rectification tower, the temperature of the top of the rectification tower is 10-25 ℃, the pressure is 5-8 Kpa, the catalyst is recovered from the bottom of the rectification tower, the temperature is 110-135 ℃, and the pressure is 6-10 Kpa. Under the condition, the separation effect can be effectively achieved, and meanwhile, the catalyst is recovered within the temperature range of 110-135 ℃, so that the catalyst can be kept within a better activity range.
Optionally, in the step (4), ammonia gas is introduced into the raffinate phase for reaction, the reaction temperature is 45-55 ℃, and the reaction time is 30-120 min, so that the lewis acid in the raffinate phase is completely separated out.
Optionally, in the step (4), when the light components are separated from the top of the tower at one time by the negative pressure rectification, the temperature of the top of the tower is 40-50 ℃, the temperature of the bottom of the tower is 160-185 ℃, and the pressure of the bottom of the tower is 0.5-2 Kpa, preferably 0.5-1.5 Kpa. Under the operating conditions, the content of light components in the tower kettle can be effectively controlled to be less than 0.5 percent, the amount of Adiponitrile (AND) in the tower kettle is controlled to be less than 1 percent, the generation of heavy boiling products is reduced, AND the purity of ADN products separated in a product rectifying tower in the later process is favorably improved.
Optionally, in the step (4), the mixture of adiponitrile and 2-methylglutaronitrile is separated by a rectifying tower, 2-methylglutaronitrile is extracted from the top of the tower, the temperature of the top of the tower is 150-160 ℃, adiponitrile is extracted from the middle part of the tower, the temperature is 165-170 ℃, and the recovery rate (i.e. yield) of adiponitrile is larger than 95%.
Further, in the steps (1) to (4), the catalyst consists of nickel and triaryl phosphite.
In the step (1), the ligand is at least one selected from triphenyl phosphite, tri-m-tolyl phosphite, tri-p-tolyl phosphite and tri-o-tolyl phosphite.
The present invention will be described in detail with reference to the following specific examples. It should also be understood that the following examples are illustrative only and are not to be construed as limiting the scope of the invention, and that numerous insubstantial modifications and adaptations of the invention described above will occur to those skilled in the art. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below.
Example 1
The method for producing adiponitrile in the embodiment comprises the following steps:
(1) primary hydrocyanation: liquid 1, 3-butadiene, liquid HCN, catalyst (consisting of nickel and triaryl phosphite) solution and ligand (triphenyl phosphite) are respectively conveyed to a large-channel reactor by a metering pump according to the proportion (the molar ratio of 1, 3-butadiene to HCN to catalyst to ligand is 210: 200: 1: 50), and the catalyst is preheated to about 120 ℃ before entering the reactor. The pressure of the large-channel reactor is controlled to be 1.0-1.5 Mpa, and the reaction temperature of primary hydrocyanation is controlled to be 90-100 ℃. The material after the reaction in the large channel enters a DSR reactor, and the reaction conditions are the same as the control of the large channel reactor.
(2) Primary hydrocyanation recovery: most of unreacted HCN and 1, 3-butadiene are removed from the material from the primary hydrocyanation through adiabatic flash evaporation, the flash evaporation temperature is controlled to be 90-110 ℃, the flash evaporation pressure is controlled to be 60-160 kpa, and the total content of hydrocyanic acid and 1, 3-Butadiene (BD) is controlled to be below 2 wt% (mass fraction). And removing residual HCN from the flash-evaporated material through a stripping tower, wherein the operating pressure is 1.5-2 bar, the tower top temperature is 8-15 ℃, and the tower kettle temperature is 120-140 ℃. The tower bottom material after passing through the stripping tower enters a 2-methyl-3-butenenitrile (2M3BN) separation tower, the temperature at the top of the separation tower is controlled to be 35-65 ℃, the pressure is controlled to be 1-10 kpa, the temperature at the bottom of the tower is controlled to be 105-130 ℃, the material mainly comprising 2-methyl-3-butenenitrile (2M3BN) is extracted from the top of the separation tower, the material also comprises 2-methyl-2-butenenitrile (2M2BN) and 2-pentenenitrile (2PN), 3-pentenenitrile (3-PN) is extracted from the side line in the tower, and a tower bottom ligand and a catalyst are mechanically applied to primary hydrocyanation.
(3) Isomerization: 2-methyl-3-butenenitrile (2M3BN) solution from the first cyanidation with a Lewis acid ZnCl2(the using amount is 0.01-0.2 mol equivalent of 2-methyl-3-butenenitrile) is mixed in a reaction kettle, the temperature is controlled at 60-100 ℃, undissolved Lewis acid is filtered after saturation, then the filtrate and a catalyst are sequentially conveyed through a large channel reactor and a DSR reactor according to the ratio (the molar ratio of 2M3BN to the catalyst is 60: 1), the reaction is controlled at 100-120 ℃, the reaction pressure is controlled at 0.3-0.8 MPa, and 2-methyl-3-butenenitrile (2M3BN) is subjected to isomerization treatment, so that the 2-methyl-3-butenenitrile (2M3BN) is converted into 3-pentenenitrile (3-PN) (namely, the reaction is firstly carried out in the large channel reactor and then carried out in the DSR reactor, and the reaction conditions of the DSR reactor are the same as those of the large channel reactor). And conveying the material after the isomerization reaction to an isomerization tower by a pump, separating a small amount of organic impurities, wherein the organic impurities comprise 2-methyl-3-butenenitrile (2M3BN), 2-pentenenitrile (2-PN) and the like, the temperature of the tower kettle is 115-125 ℃, the pressure is-0.06 MPa-0.08 MPa, and the material in the tower kettle enters a secondary hydrocyanation reaction.
(4) Secondary hydrocyanation: mixing the 3-pentenenitrile (3-PN) from the step (1) and the material (the isomerized material contains 3PN and a catalyst) from the step (3) with liquid HCN and the catalyst according to a ratio (the molar ratio of the catalyst to HCN to 3PN is 1: 50: 65), sequentially conveying the mixture into a large-channel reactor and an SR reactor, controlling the temperature at 70-90 ℃ and the pressure at about 0.4-0.5 Mpa, carrying out secondary hydrocyanation, and reacting to generate adiponitrile (namely conveying the material into the large-channel reactor according to a ratio by using a metering pump, and after the reaction is finished, conveying the material into the DSR reactor for reaction, wherein the reaction condition of the DSR reactor is the same as that of the large-channel reactor).
(5) Rectification, separation and recovery: recovering unreacted HCN and 3-pentenenitrile from the material after twice hydrocyanation in a rectification mode, wherein the operating pressure of a tower for recovering the HCN is less than or equal to 90kpa, the temperature of the top of the tower is 8-10 ℃, the temperature of a bottom of the tower is 120-130 ℃, so as to control the concentration of hydrocyanic acid (HCN) in the bottom of the tower to be less than 0.01%; the operation pressure of the 3-pentenenitrile recovery tower is less than or equal to 2kpa, the tower top temperature is 40-50 ℃, and the tower kettle temperature is 115-125 ℃.
Extracting the rest materials to separate out the catalyst, wherein the extracting agent is cyclohexane, and the extraction temperature is controlled to be 50-65 ℃; and then recovering the extractant cyclohexane from the extraction phase through the top of the rectifying tower, wherein the temperature of the top of the rectifying tower is controlled to be 20-25 ℃, the pressure is 5-8 Kpa, the catalyst is recovered from the bottom of the rectifying tower, the temperature is 110-135 ℃, and the pressure is 8-10 Kpa.
(6) Introducing ammonia into raffinate: and (3) adding the raffinate phase obtained in the step (5) into a reaction kettle, gradually introducing ammonia gas, controlling the reaction temperature to be 45-55 ℃, and reacting for 60 min. After the reaction is finished, filtering AND separating the material liquid by a centrifugal machine, removing solid waste from an obtained filter cake, removing excessive ammonia from a filtrate by nitrogen, then carrying out negative pressure rectification, separating a light component (the light component comprises cyclohexane, 3PN AND m-cresol, wherein the cyclohexane is an extracting agent in residual materials, AND the m-cresol is a decomposition product in reaction materials) from the top of the tower at one time, AND separating a mixture of 2-methylglutaronitrile AND adiponitrile (namely a 2-MGN/ADN mixture) from the lateral line, wherein in the process, the temperature of the top of the tower is 40-50 ℃, the temperature of a tower kettle is 165-175 ℃, the pressure of the tower kettle is 0.5-1.5 Kpa, so as to control the content of the light component in the tower kettle to be less than 0.5%, control the amount of Adiponitrile (AND) in the tower kettle to be less than 1%, AND reduce the generation of heavy boiling products.
(7) And (2) separating the 2-MGN/ADN mixture in a rectifying tower, collecting 2-methylglutaronitrile (2-MGN) from the top of the tower, wherein the temperature of the top of the tower is 150-160 ℃, and collecting an Adiponitrile (ADN) product from the middle part of the tower, wherein the temperature is 165-170 ℃. Through calculation and detection, the yield of the adiponitrile is 97.8 percent, and the purity of the obtained adiponitrile reaches the requirement of qualified products (the purity is more than 99.5 percent).
Example 2
The method for producing adiponitrile in the embodiment comprises the following steps:
(1) primary hydrocyanation: liquid 1, 3-butadiene, liquid HCN, catalyst (consisting of nickel and triaryl phosphite) solution and ligand (tri-m-toluyl phosphite) are respectively conveyed to a large-channel reactor by a metering pump according to the proportion (the molar ratio of 1, 3-butadiene to HCN to catalyst to ligand is 330: 300: 1: 50), and the catalyst is preheated to about 120 ℃ before entering the reactor. The pressure of the large-channel reactor is controlled to be 1.0-1.5 Mpa, and the reaction temperature of primary hydrocyanation is controlled to be 90-100 ℃. The material after the reaction in the large channel enters a DSR reactor, and the reaction conditions are the same as the control of the large channel reactor.
(2) Primary hydrocyanation recovery: most of unreacted HCN and 1, 3-butadiene are removed from the material from the primary hydrocyanation through adiabatic flash evaporation, the flash evaporation temperature is controlled to be 90-110 ℃, the flash evaporation pressure is controlled to be 60-160 kpa, and the total content of hydrocyanic acid and 1, 3-Butadiene (BD) is controlled to be below 2 wt% (mass fraction). And removing residual HCN from the flash-evaporated material through a stripping tower, wherein the operating pressure is 1.5-2 bar, the tower top temperature is 8-15 ℃, and the tower kettle temperature is 120-140 ℃. The tower bottom material after passing through the stripping tower enters a 2-methyl-3-butenenitrile (2M3BN) separation tower, the temperature at the top of the separation tower is controlled to be 35-65 ℃, the pressure is controlled to be 1-10 kpa, the temperature at the bottom of the tower is controlled to be 105-130 ℃, the material mainly comprising 2-methyl-3-butenenitrile (2M3BN) is extracted from the top of the separation tower, the material also comprises 2-methyl-2-butenenitrile (2M2BN) and 2-pentenenitrile (2PN), 3-pentenenitrile (3-PN) is extracted from the side line in the tower, and a tower bottom ligand and a catalyst are mechanically applied to primary hydrocyanation.
(3) Isomerization: 2-methyl-3-butenenitrile (2M3BN) solution from the first cyanidation with a Lewis acid ZnCl2(the dosage is 0.1mol equivalent of 2-methyl-3-butenenitrile) is mixed in a reaction kettle, the temperature is controlled between 60 ℃ and 100 ℃, undissolved Lewis acid is filtered after saturation, and then filtrate and catalyst are sequentially conveyed to pass through a large-channel reactor and DS according to the proportion (the molar ratio of 2M3BN to the catalyst is 60: 1)And (2) in the R reactor, controlling the reaction at 120-140 ℃ and the reaction pressure at 0.3-0.8 MPa, and carrying out isomerization treatment on the 2-methyl-3-butenenitrile (2M3BN) to convert the 2-methyl-3-butenenitrile (2M3BN) into 3-pentenenitrile (3-PN) (firstly reacting in a large channel reactor and then reacting in a DSR reactor, wherein the reaction conditions of the DSR reactor are the same as those of the large channel reactor). And conveying the material after the isomerization reaction to an isomerization tower by a pump, separating a small amount of organic impurities, wherein the organic impurities comprise 2-methyl-3-butenenitrile (2M3BN), 2-pentenenitrile (2-PN) and the like, the temperature of the tower kettle is 115-125 ℃, the pressure is-0.06 MPa-0.08 MPa, and the material in the tower kettle enters a secondary hydrocyanation reaction.
(4) Secondary hydrocyanation: mixing the 3-pentenenitrile (3-PN) from the step (1) and the material (the isomerized material contains 3PN and a catalyst) from the step (3) with liquid HCN and the catalyst according to a ratio (the molar ratio of the catalyst to HCN to 3PN is 1: 40: 60), sequentially conveying the mixture into a large-channel reactor and an SR reactor, controlling the temperature at 60-80 ℃ and the pressure at 0.5-0.6 Mpa, carrying out secondary hydrocyanation, and reacting to generate adiponitrile (reacting in the large-channel reactor and then in the DSR reactor, wherein the reaction conditions of the DSR reactor are the same as those of the large-channel reactor).
(5) Rectification, separation and recovery: recovering unreacted HCN and 3-pentenenitrile from the material after twice hydrocyanation in a rectification mode, wherein the operating pressure of a tower for recovering the HCN is less than or equal to 90kpa, the temperature of the top of the tower is 8-10 ℃, the temperature of a tower kettle is 125-135 ℃, so as to control the concentration of hydrocyanic acid (HCN) in the tower kettle to be less than 0.01%; the operation pressure of the 3-pentenenitrile recovery tower is less than or equal to 2kpa, the tower top temperature is 30-40 ℃, and the tower kettle temperature is 110-115 ℃.
Extracting the rest materials to separate out the catalyst, wherein the extracting agent is cyclohexane, and the extraction temperature is controlled to be 50-65 ℃; and then recovering the extractant cyclohexane from the extraction phase through the top of the rectifying tower, wherein the temperature of the top of the rectifying tower is controlled to be 10-15 ℃, the pressure is 5-8 Kpa, the catalyst is recovered from the bottom of the rectifying tower, the temperature is 110-135 ℃, and the pressure is 6-8 Kpa.
(6) Introducing ammonia into raffinate: and (3) adding the raffinate phase obtained in the step (5) into a reaction kettle, gradually introducing ammonia gas, controlling the reaction temperature to be 45-55 ℃, and reacting for 30 min. After the reaction is finished, filtering AND separating the material liquid by a centrifugal machine, removing solid waste from an obtained filter cake, removing excessive ammonia from a filtrate by nitrogen, performing negative pressure rectification, AND separating a light component (the light component comprises cyclohexane, 3PN AND m-cresol, wherein the cyclohexane is an extracting agent in residual materials, AND the m-cresol is a decomposition product in reaction materials) from the top of the tower at one time, wherein the temperature of the top of the tower is 40-50 ℃, the temperature of a tower kettle is 175-185 ℃, the pressure of the tower kettle is 1-2 Kpa, so that the content of the light component in the tower kettle is controlled to be less than 0.5%, the amount of dinitrile (AND) in the tower kettle is controlled to be less than 1%, AND the generation of a heavy boiling product is reduced.
(7) And (2) separating the 2-MGN/ADN mixture in a rectifying tower, collecting 2-methylglutaronitrile (2-MGN) from the top of the tower, wherein the temperature of the top of the tower is 150-160 ℃, and collecting an Adiponitrile (ADN) product from the middle part of the tower, wherein the temperature is 165-170 ℃. The calculation and detection show that the yield of the adiponitrile is 97.2 percent, and the purity of the adiponitrile reaches the requirement of qualified products (the purity is more than 99.7 percent).
Example 3
The method for producing adiponitrile in the embodiment comprises the following steps:
(1) primary hydrocyanation: liquid 1, 3-butadiene, liquid HCN, catalyst (consisting of nickel and triaryl phosphite) solution and ligand (tri-p-methylphenyl phosphite) are respectively conveyed to a large-channel reactor by a metering pump according to the proportion (the molar ratio of the 1, 3-butadiene to the HCN to the catalyst to the ligand is 210: 175: 1: 40), and the catalyst is preheated to about 120 ℃ before entering the reactor. The pressure of the large-channel reactor is controlled to be 1.0-1.5 Mpa, and the reaction temperature of primary hydrocyanation is controlled to be 90-100 ℃. The material after the reaction in the large channel enters a DSR reactor, and the reaction conditions are the same as the control of the large channel reactor.
(2) Primary hydrocyanation recovery: most of unreacted HCN and 1, 3-butadiene are removed from the material from the primary hydrocyanation through adiabatic flash evaporation, the flash evaporation temperature is controlled to be 90-110 ℃, the flash evaporation pressure is controlled to be 60-160 kpa, and the total content of hydrocyanic acid and 1, 3-Butadiene (BD) is controlled to be below 2 wt% (mass fraction). And removing residual HCN from the flash-evaporated material through a stripping tower, wherein the operating pressure is 1.5-2 bar, the tower top temperature is 8-15 ℃, and the tower kettle temperature is 120-140 ℃. The tower bottom material after passing through the stripping tower enters a 2-methyl-3-butenenitrile (2M3BN) separation tower, the temperature at the top of the separation tower is controlled to be 35-65 ℃, the pressure is controlled to be 1-10 kpa, the temperature at the bottom of the tower is controlled to be 105-130 ℃, the material mainly comprising 2-methyl-3-butenenitrile (2M3BN) is extracted from the top of the separation tower, the material also comprises 2-methyl-2-butenenitrile (2M2BN) and 2-pentenenitrile (2PN), 3-pentenenitrile (3-PN) is extracted from the side line in the tower, and a tower bottom ligand and a catalyst are mechanically applied to primary hydrocyanation.
(3) Isomerization: 2-methyl-3-butenenitrile (2M3BN) solution from the first cyanidation with a Lewis acid ZnCl2(the using amount is 0.01-0.2 mol equivalent of 2-methyl-3-butenenitrile) is mixed in a reaction kettle, the temperature is controlled at 60-100 ℃, undissolved Lewis acid is filtered after saturation, then the filtrate and a catalyst are sequentially conveyed through a large channel reactor and a DSR reactor according to the ratio (the molar ratio of 2M3BN to the catalyst is 60: 1), the reaction is controlled at 125-145 ℃, the reaction pressure is controlled at 0.3-0.8 MPa, and 2-methyl-3-butenenitrile (2M3BN) is subjected to isomerization treatment, so that the 2-methyl-3-butenenitrile (2M3BN) is converted into 3-pentenenitrile (3-PN) (the reaction is firstly carried out in the large channel reactor and then in the DSR reactor, and the reaction conditions of the DSR reactor are the same as those of the large channel reactor). And separating a small amount of organic impurities from the material after the isomerization reaction by adopting a low-temperature crystallization separation mode, wherein the organic impurities comprise 2-methyl-3-butenenitrile (2M3BN), 2-pentenenitrile (2-PN) and the like, the temperature is controlled to be 20-70 ℃, the pressure is normal pressure, and the material at the bottom of the tower enters a secondary hydrocyanation reaction.
(4) Secondary hydrocyanation: mixing the 3-pentenenitrile (3-PN) from the step (1) and the material (the isomerized material contains 3PN and a catalyst) from the step (3) with liquid HCN and the catalyst according to a ratio (the molar ratio of the catalyst to HCN to 3PN is 1: 55: 70), sequentially conveying the mixture into a large-channel reactor and an SR reactor, controlling the temperature at 70-80 ℃ and the pressure at 0.6-0.8 Mpa, carrying out secondary hydrocyanation, and reacting to generate adiponitrile (reacting in the large-channel reactor and then in the DSR reactor, wherein the reaction conditions of the DSR reactor are the same as those of the large-channel reactor).
(5) Rectification, separation and recovery: recovering unreacted HCN and 3-pentenenitrile from the material after twice hydrocyanation in a rectification mode, wherein the operating pressure of a tower for recovering the HCN is less than or equal to 90kpa, the temperature of the top of the tower is 8-10 ℃, the temperature of a bottom of the tower is 120-130 ℃, so as to control the concentration of hydrocyanic acid (HCN) in the bottom of the tower to be less than 0.01%; the operation pressure of the 3-pentenenitrile recovery tower is less than or equal to 2kpa, the tower top temperature is 35-45 ℃, and the tower kettle temperature is 105-115 ℃.
Extracting the rest materials to separate out the catalyst, wherein the extracting agent is cyclohexane, and the extraction temperature is controlled to be 50-65 ℃; and then recovering the extractant cyclohexane from the extraction phase through the top of the rectifying tower, wherein the temperature of the top of the rectifying tower is controlled to be 15-20 ℃, the pressure is 5-8 Kpa, the catalyst is recovered from the bottom of the rectifying tower, the temperature is 110-135 ℃, and the pressure is 6-8 Kpa.
(6) Introducing ammonia into raffinate: and (3) adding the raffinate phase obtained in the step (5) into a reaction kettle, gradually introducing ammonia gas, controlling the reaction temperature to be 45-55 ℃, and reacting for 120 min. After the reaction is finished, filtering AND separating the material liquid by a centrifugal machine, removing solid waste from an obtained filter cake, removing excessive ammonia from a filtrate by nitrogen, then carrying out negative pressure rectification, separating a light component (the light component comprises cyclohexane, 3PN AND m-cresol, wherein the cyclohexane is an extracting agent in residual materials, AND the m-cresol is a decomposition product in reaction materials) from the top of the tower at one time, AND separating a mixture of 2-methylglutaronitrile AND adiponitrile (namely a 2-MGN/ADN mixture) from the lateral line at the top of the tower, wherein in the process, the temperature of the top of the tower is 40-50 ℃, the temperature of a tower kettle is 170-185 ℃, the pressure of the tower kettle is 0.5-2 Kpa, so as to control the content of the light component in the tower kettle to be less than 0.5%, control the amount of Adiponitrile (AND) in the tower kettle to be less than 1%, AND reduce the generation of heavy boiling products.
(7) And (2) separating the 2-MGN/ADN mixture in a rectifying tower, collecting 2-methylglutaronitrile (2-MGN) from the top of the tower, wherein the temperature of the top of the tower is 150-160 ℃, and collecting an Adiponitrile (ADN) product from the middle part of the tower, wherein the temperature is 165-170 ℃. Through calculation and detection, the yield of the adiponitrile is 95.9 percent, and the purity of the obtained adiponitrile reaches the requirement of qualified products (the purity is more than 99.8 percent).
Example 4
The method for producing adiponitrile in the embodiment comprises the following steps:
(1) primary hydrocyanation: liquid 1, 3-butadiene, liquid HCN, catalyst (consisting of nickel and triaryl phosphite) solution and ligand (tricresyl phosphite) are respectively conveyed to a large-channel reactor by a metering pump according to the proportion (the molar ratio of the 1, 3-butadiene to the HCN to the catalyst to the ligand is 100: 90: 1: 20), and the catalyst is preheated to about 120 ℃ before entering the reactor. The pressure of the large-channel reactor is controlled to be 1.0-1.5 Mpa, and the reaction temperature of primary hydrocyanation is controlled to be 90-100 ℃. The material after the reaction in the large channel enters a DSR reactor, and the reaction conditions are the same as the control of the large channel reactor.
(2) Primary hydrocyanation recovery: most of unreacted HCN and 1, 3-butadiene are removed from the material from the primary hydrocyanation through adiabatic flash evaporation, the flash evaporation temperature is controlled to be 90-110 ℃, the flash evaporation pressure is controlled to be 60-160 kpa, and the total content of hydrocyanic acid and 1, 3-Butadiene (BD) is controlled to be below 2 wt% (mass fraction). And removing residual HCN from the flash-evaporated material through a stripping tower, wherein the operating pressure is 1.5-2 bar, the tower top temperature is 8-15 ℃, and the tower kettle temperature is 120-140 ℃. The tower bottom material after passing through the stripping tower enters a 2-methyl-3-butenenitrile (2M3BN) separation tower, the temperature at the top of the separation tower is controlled to be 35-65 ℃, the pressure is controlled to be 1-10 kpa, the temperature at the bottom of the tower is controlled to be 105-130 ℃, the material mainly comprising 2-methyl-3-butenenitrile (2M3BN) is extracted from the top of the separation tower, the material also comprises 2-methyl-2-butenenitrile (2M2BN) and 2-pentenenitrile (2PN), 3-pentenenitrile (3-PN) is extracted from the side line in the tower, and a tower bottom ligand and a catalyst are mechanically applied to primary hydrocyanation.
(3) Isomerization: 2-methyl-3-butenenitrile (2M3BN) solution from the first cyanidation with a Lewis acid ZnCl2(the using amount is 0.01-0.2 mol equivalent of 2-methyl-3-butenenitrile) is mixed in a reaction kettle, the temperature is controlled at 60-100 ℃, undissolved Lewis acid is filtered after saturation, then filtrate and a catalyst are sequentially conveyed through a large channel reactor and a DSR reactor according to the ratio (the molar ratio of 2M3BN to the catalyst is 60: 1), the reaction is controlled at 135-145 ℃, the reaction pressure is controlled at 0.3-0.8 MPa, and 2-methyl-3-butenenitrile (2M3BN) is subjected to isomerization treatment, so that the 2-methyl-3-butenenitrile (2M3BN) is converted into 3-pentenenitrile (3-PN) (the 2-methyl-3-butenenitrile (3-PN) is firstly reacted in the large channel reactor and then reacted in the DSR reactor, and the reaction conditions of the DSR reactor are the same as those of the large channel reactor). The material after the isomerization reaction is conveyed to an isomerization tower by a pump, and a small amount of organic matter is separatedImpurities and organic impurities comprise 2-methyl-3-butenenitrile (2M3BN), 2-pentenenitrile (2-PN) and the like, the temperature of a tower kettle is 115-125 ℃, the pressure is-0.06 MPa-0.08 MPa, and the materials in the tower kettle enter a secondary hydrocyanation reaction.
(4) Secondary hydrocyanation: mixing the 3-pentenenitrile (3-PN) from the step (1) and the material (the isomerized material contains 3PN and a catalyst) from the step (3) with liquid HCN and the catalyst according to a ratio (the molar ratio of the catalyst to HCN to 3PN is 1: 60), sequentially conveying the mixture into a large-channel reactor and an SR reactor, controlling the temperature at 60-80 ℃ and the pressure at 0.5-0.7 Mpa, carrying out secondary hydrocyanation, and reacting to generate adiponitrile (reacting in the large-channel reactor and then in the DSR reactor, wherein the reaction conditions of the DSR reactor are the same as those of the large-channel reactor).
(5) Rectification, separation and recovery: recovering unreacted HCN and 3-pentenenitrile from the material after twice hydrocyanation in a rectification mode, wherein the operating pressure of a tower for recovering the HCN is less than or equal to 90kpa, the temperature of the top of the tower is 8-10 ℃, the temperature of a tower kettle is 125-135 ℃, so as to control the concentration of hydrocyanic acid (HCN) in the tower kettle to be less than 0.01%; the operation pressure of the 3-pentenenitrile recovery tower is less than or equal to 2kpa, the tower top temperature is 40-50 ℃, and the tower kettle temperature is 110-120 ℃.
Extracting the rest materials to separate out the catalyst, wherein the extracting agent is cyclohexane, and the extraction temperature is controlled to be 50-65 ℃; and then recovering the extractant cyclohexane from the extraction phase through the top of the rectifying tower, wherein the temperature of the top of the rectifying tower is controlled to be 15-20 ℃, the pressure is 5-8 Kpa, the catalyst is recovered from the bottom of the rectifying tower, the temperature is 110-135 ℃, and the pressure is 8-10 Kpa.
(6) Introducing ammonia into raffinate: and (3) adding the raffinate phase obtained in the step (5) into a reaction kettle, gradually introducing ammonia gas, controlling the reaction temperature to be 45-55 ℃, and reacting for 100 min. After the reaction is finished, filtering AND separating the material liquid by a centrifugal machine, removing solid waste from an obtained filter cake, removing excessive ammonia from a filtrate by nitrogen, then carrying out negative pressure rectification, separating a light component (the light component comprises cyclohexane, 3PN AND m-cresol, wherein the cyclohexane is an extracting agent in residual materials, AND the m-cresol is a decomposition product in reaction materials) from the top of the tower at one time, AND separating a mixture of 2-methylglutaronitrile AND adiponitrile (namely a 2-MGN/ADN mixture) from the lateral line, wherein in the process, the temperature of the top of the tower is 40-50 ℃, the temperature of a tower kettle is 165-175 ℃, the pressure of the tower kettle is 0.5-1.5 Kpa, so as to control the content of the light component in the tower kettle to be less than 0.5%, control the amount of Adiponitrile (AND) in the tower kettle to be less than 1%, AND reduce the generation of heavy boiling products.
(7) And (2) separating the 2-MGN/ADN mixture in a rectifying tower, collecting 2-methylglutaronitrile (2-MGN) from the top of the tower, wherein the temperature of the top of the tower is 150-160 ℃, and collecting an Adiponitrile (ADN) product from the middle part of the tower, wherein the temperature is 165-170 ℃. Through calculation and detection, the yield of the adiponitrile is 96.5 percent, and the purity of the obtained adiponitrile reaches the requirement of qualified products (the purity is more than 99.6 percent).
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims (10)

1. A method for producing adiponitrile, comprising the steps of:
(1) primary hydrocyanation: mixing 1, 3-butadiene, hydrocyanic acid, a catalyst and a ligand, then sequentially carrying out primary hydrocyanation in a large-channel reactor and a DSR reactor, carrying out adiabatic flash evaporation on a material obtained after the primary hydrocyanation to remove 1, 3-butadiene and most of unreacted hydrocyanic acid, removing residual hydrocyanic acid from the flashed material through a stripping tower, feeding a tower bottom material subjected to the stripping tower into a separation tower, extracting a material mainly containing 2-methyl-3-butenenitrile from the top of the separation tower, extracting 3-pentenenitrile from the side line of the tower, and mechanically applying the tower bottom ligand and the catalyst to the primary hydrocyanation;
(2) isomerization: mixing the 2-methyl-3-butenenitrile solution from primary hydrocyanation with Lewis acid, filtering to remove undissolved Lewis acid after saturation, sequentially conveying the filtrate and a catalyst in proportion through a large channel reactor and a DSR reactor, and carrying out isomerization treatment on the 2-methyl-3-butenenitrile to convert the 2-methyl-3-butenenitrile into 3-pentenenitrile;
(3) secondary hydrocyanation: conveying the 3-pentenenitrile from the step (1), the isomerized material from the step (2), hydrocyanic acid and a catalyst in proportion sequentially through a large channel reactor and a DSR reactor, and carrying out secondary hydrocyanation to generate adiponitrile; wherein the feed from the isomerization in step (2) contains 3-pentenenitrile and a catalyst.
2. The method of claim 1, wherein: in the step (1), the reaction conditions of the large-channel reactor and the DSR reactor are controlled to be the same, the pressure is controlled to be 1.0-1.5 Mpa, and the reaction temperature of primary hydrocyanation is controlled to be 90-100 ℃;
and/or in the step (1), the flash evaporation temperature is controlled to be 90-110 ℃, and the flash evaporation pressure is 60-160 kpa;
and/or in the step (1), when the residual hydrocyanic acid is removed through a stripping tower, the operating pressure is 1.5-2 bar, the tower top temperature is 8-15 ℃, and the tower kettle temperature is 120-140 ℃;
and/or in the step (1), the temperature of the top of the separation tower is controlled to be 35-65 ℃, the pressure is controlled to be 1-10 kpa, and the temperature of the bottom of the separation tower is controlled to be 105-130 ℃;
and/or in the step (1), the molar ratio of the 1, 3-butadiene, the hydrocyanic acid, the catalyst and the ligand is 100-500: 90-400: 1: 20-100.
3. The method of claim 1, wherein: in the step (2), when the 2-methyl-3-butenenitrile solution from primary hydrocyanation is mixed with Lewis acid, the temperature is controlled to be 60-100 ℃;
and/or, in the step (2), the Lewis acid is selected from ZnCl2、ZnBr2、ZnI2、AlCl3、SnCl4、TiCl3At least one of Triphenylboron (TPB);
and/or in the step (2), the dosage of the Lewis acid is 0.01-0.2 mol equivalent of 2-methyl-3-butenenitrile, and the dosage of the catalyst is 0.01-0.02 mol equivalent of 2-methyl-3-butenenitrile; the molar ratio of the Lewis acid to the catalyst is 1: 4-6;
and/or in the step (2), the reaction temperature of the materials in the large channel reactor and the DSR reactor is controlled to be 100-145 ℃, and the pressure is 0.3-0.8 MPa.
4. The method of claim 1, wherein: in the step (2), after the isomerization treatment is finished, impurities also need to be separated, and the separation method is selected from one of the following two modes:
A. conveying the material after the isomerization reaction to the middle part of an isomerization tower, separating a small amount of organic impurities, wherein the temperature of a tower kettle is 105-125 ℃, and the pressure is-0.1 MPa-0.01 MPa;
B. and (3) carrying out low-temperature crystallization separation on the material after the isomerization reaction is finished, controlling the temperature to be 20-70 ℃ and the pressure to be normal pressure, and separating out a small amount of organic impurities.
5. The method of claim 1, wherein: in the step (3), during secondary hydrocyanation, the mole ratio of the catalyst to hydrocyanic acid (HCN) to 3-pentenenitrile (2-PN) is 1: 40-60: 60-70;
and/or in the step (3), during secondary hydrocyanation, the reaction temperature is controlled to be 60-90 ℃, and the pressure is controlled to be 0.4-0.8 Mpa.
6. The method of claim 1, wherein: the method further comprises the step (4): and separating the material after the secondary hydrocyanation reaction in a rectification mode to obtain adiponitrile and 2-methylglutaronitrile, and recovering the catalyst and unreacted hydrocyanic acid and 3-pentenenitrile.
7. The method of claim 6, wherein: in the step (4), the material after the secondary hydrocyanation reaction is firstly rectified to sequentially recover unreacted hydrocyanic acid and 3-pentenenitrile, then the residual material is extracted to separate out the catalyst, ammonia gas is introduced into the raffinate phase to carry out the reaction, the material is centrifuged and filtered to separate after the reaction is finished, the obtained filtrate is subjected to negative pressure rectification after excessive ammonia is removed, light components are separated from the top of the tower at one time, the light components comprise an extracting agent, 3-pentenenitrile and m-cresol, the mixture of adiponitrile and 2-methylglutaronitrile is extracted from the side line, and then the adiponitrile product is obtained through rectification separation.
8. The method of claim 7, wherein: in the step (4), the operating pressure of the hydrocyanic acid recovery tower is less than or equal to 90kpa, the temperature of the top of the tower is 8-10 ℃, and the temperature of the bottom of the tower is 120-135 ℃ so as to control the concentration of hydrocyanic acid in the bottom of the tower to be less than 0.01%;
and/or in the step (4), the operation pressure of the tower for recovering the 3-pentenenitrile is less than or equal to 2kpa, the temperature of the top of the tower is 30-50 ℃, and the temperature of the bottom of the tower is 105-125 ℃;
and/or in the step (4), during extraction, the temperature is 50-65 ℃, and the extracting agent is at least one selected from cyclohexane, cyclopentane, n-hexane, n-pentane and n-heptane;
and/or in the step (4), after extraction, recovering an extractant from an extraction phase through the top of a rectifying tower, wherein the temperature of the top of the rectifying tower is 10-25 ℃, the pressure is 5-8 Kpa, and the temperature of a tower kettle is 110-135 ℃, and the pressure is 6-10 Kpa;
and/or in the step (4), introducing ammonia gas into the raffinate phase for reaction, wherein the reaction temperature is 45-55 ℃, and the reaction time is 30-120 min.
9. The method of claim 7, wherein: in the step (4), when the light components are separated from the top of the tower at one time by negative pressure rectification, the temperature of the top of the tower is 40-50 ℃, the temperature of a tower kettle is 160-185 ℃, and the pressure of the tower kettle is 0.5-2 Kpa; and/or in the step (4), separating the mixture of adiponitrile and 2-methylglutaronitrile by a rectifying tower, and extracting 2-methylglutaronitrile from the top of the tower, wherein the temperature of the top of the tower is 150-160 ℃, and the temperature of adiponitrile extracted from the middle part of the tower is 165-170 ℃.
10. The method of claim 1, wherein: in the steps (1) to (4), the catalyst consists of nickel and triaryl phosphite;
and/or, in the step (1), the ligand is at least one selected from triphenyl phosphite, tri-m-cresyl phosphite, tri-p-cresyl phosphite and tri-o-cresyl phosphite.
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