CN113444018B - Adiponitrile production method - Google Patents
Adiponitrile production method Download PDFInfo
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- CN113444018B CN113444018B CN202110716184.1A CN202110716184A CN113444018B CN 113444018 B CN113444018 B CN 113444018B CN 202110716184 A CN202110716184 A CN 202110716184A CN 113444018 B CN113444018 B CN 113444018B
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- 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
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- 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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/584—Recycling of catalysts
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 hydrocyanic acid in a large-channel reactor and a DSR reactor, carrying out adiabatic flash evaporation on materials obtained after primary hydrocyanic acid to remove 1, 3-butadiene and most unreacted hydrocyanic acid, then removing residual hydrocyanic acid through a stripping tower, entering a separation tower, extracting 2-methyl-3-butenenitrile from the top of the tower, and extracting 3-pentenenitrile from the side line of the tower; (2) Adding Lewis acid and catalyst into the 2-methyl-3-butenenitrile solution from the primary hydrocyanation to isomerize into 3-pentenenitrile; (3) And (3) hydrocyanating the 3-pentenenitrile from step (1), the material from step (2) and hydrocyanic acid twice to produce adiponitrile. The method can reduce the loss of products and raw materials and the risk of catalyst poisoning, is an efficient, environment-friendly, high-yield and economical adiponitrile synthesis method, and is suitable for industrial production.
Description
Technical Field
The invention relates to the technical field of organic synthesis, in particular to a method for producing adiponitrile.
Background
Adiponitrile (ADN) is a colorless to pale yellow transparent liquid, slightly odorous, slightly water-soluble, ether-soluble, alcohol-soluble, and is one of the essential raw materials for producing nylon 66. Hydrogenation reduction of adiponitrile to obtain hexamethylenediamine, and polycondensation of hexamethylenediamine and adipic acid to obtain nylon 66. Adiponitrile can also be used for preparing chemical products such as caprolactam, can also be used for textile industry and electroplating industry, and has wide application in the chemical field.
The current process routes for producing adiponitrile mainly comprise an acrylonitrile electrolytic method, a butadiene hydrocyanation method, an adipic acid catalytic ammonification method and the like. Butadiene hydrocyanation processes are classified into butadiene hydrocyanation chloride processes and butadiene direct hydrocyanation processes. The butadiene hydrocyanation method is a method developed by Dupont in the beginning of 60 th century, and has the advantages of complex process, serious corrosion, large investment and large consumption of chlorine and hydrocyanic acid, and is eliminated. At the beginning of the 70 s, dupont developed a direct hydrocyanation method of butadiene without chlorine, which avoids the pollution problem caused by electrolysis of sodium chloride and removal of sodium chloride in the chloridizing-cyanidation method, reduces the raw material cost by 15% and saves energy by 45% compared with the chloridizing method. The direct cyanation method of butadiene is the most mainstream adiponitrile production process route at present, and the method has the characteristics of wide raw materials, short process route, higher yield, small pollution and the like, is called as a process showing green competitiveness, and is the most reasonable adiponitrile preparation method with best atomic economy at present.
Principle of direct hydrocyanation of butadiene: the direct hydrocyanation of butadiene to adiponitrile involves three steps, primary cyanidation, isomerization, and secondary cyanidation, using a transition metal catalyst that introduces two molecules of HCN into butadiene, typically using a complex of transition metals such as Ni, rh, ru, etc.
For example: patent publication CN103180290a discloses a method for producing nitrile, which discloses a butadiene method for synthesizing adiponitrile mainly comprising three steps of hydrocyanation, isomerization and double hydrocyanation, wherein the reaction equations of the three steps are as follows:
(1) Primary hydrocyanation
(2) Isomerization of
(3) Secondary hydrocyanation
The patent with publication No. CN103012197A also discloses a preparation method of 3-pentenenitrile and a preparation method of adiponitrile, wherein the synthesis of adiponitrile by a butadiene method mainly comprises two steps of primary hydrocyanation and secondary hydrocyanation, and the reaction equations of the two steps are as follows:
however, the following problems exist in both the three-stage synthesis of adiponitrile from butadiene and the two-stage synthesis of adiponitrile from butadiene: (1) After the primary hydrocyanation reaction, butadiene, hydrocyanic acid and nickel catalyst are respectively recovered, 3-pentenenitrile is separated and purified, and then the 3-pentenenitrile and the hydrocyanic acid are subjected to secondary hydrocyanation reaction to obtain adiponitrile crude product. The conversion rate of the primary hydrocyanation reaction is 70-72%, the selectivity is 72-75%, the conversion rate of the secondary hydrocyanation reaction is 70-72%, and the selectivity is 75-80%; (2) The reaction is carried out in a conventional autoclave, the multiphase reaction materials are mixed poorly, the reaction time is long, and the yield and the selectivity are low; (3) Multiple times of rectification are needed, so that material polymerization and catalyst decomposition are caused, and the production cost is greatly increased.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, it is an object of the present invention to provide a process for the production of adiponitrile which simplifies the process flow, increases the product yield, reduces the equipment and production costs, and reduces the losses of product 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, carrying out adiabatic flash evaporation on the material obtained after primary hydrocyanation to remove 1, 3-butadiene and most of unreacted hydrocyanic acid, removing residual hydrocyanic acid from the material obtained after flash evaporation through a stripping tower, feeding the material at the tower bottom after the stripping into a separation tower, extracting the material mainly comprising 2-methyl-3-butenenitrile (2M 3 BN), 2-methyl-2-butenenitrile (2M 2 BN) and 2-pentenenitrile (2 PN), extracting 3-pentenenitrile (3-PN) from the side line of the tower, and applying the ligand and the catalyst to primary hydrocyanation;
(2) Isomerization: mixing 2-methyl-3-butenenitrile (2M 3 BN) solution from primary hydrocyanation with Lewis acid, filtering to remove undissolved Lewis acid after saturation, sequentially conveying filtrate and catalyst in proportion through a large-channel reactor and a DSR reactor, and carrying out isomerization treatment (namely, firstly reacting in the large-channel reactor and then reacting in the DSR reactor) on the 2-methyl-3-butenenitrile (2M 3 BN) to convert the 2-methyl-3-butenenitrile (2M 3 BN) into 3-pentenenitrile (3-PN);
(3) Secondary hydrocyanation: sequentially conveying 3-pentenenitrile (3-PN) from the step (1), isomerized material from the step (2), hydrocyanic acid and a catalyst through a large-channel reactor and a DSR reactor according to a proportion for 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 material from the isomerisation in step (2) comprises 3-pentenenitrile and a certain amount 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 the primary hydrocyanation is controlled to be 90-100 ℃.
In the step (1), 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 2wt% (mass fraction).
Further, in the step (1), when 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 bottom 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 (2M 3 BN) solution from the primary hydrocyanation is mixed with a Lewis acid, the temperature is controlled to be 60 to 100 ℃.
Further, in the step (2), the Lewis acid is selected from ZnCl 2 、ZnBr 2 、ZnI 2 、AlCl 3 、SnCl 4 、TiCl 3 At least one of Triphenylboron (TPB). The Lewis acid has the function of improving the catalytic activity of the catalyst, thereby improving the reaction speed and the selectivity of the modulation reaction.
Further, in the step (2), the amount of the Lewis acid is 0.01 to 0.2mol equivalent of 2-methyl-3-butenenitrile, and the amount of the catalyst is 0.01 to 0.02mol equivalent of 2-methyl-3-butenenitrile; the molar ratio of Lewis acid to 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 between 110 and 130 ℃. The reaction temperature is controlled near the boiling point of 2-methyl-3-butenenitrile (2M 3 BN), the catalytic activity is highest, the reaction speed is faster, and the selectivity is higher.
Further, in the step (2), after the isomerization treatment is finished, impurities are further required to be separated, and the separation method is selected from one of the following two modes:
A. conveying the material after isomerization reaction to the top of an isomerization tower, separating out a small amount of organic impurities, wherein the temperature of the tower kettle is 115-125 ℃, and the pressure is-0.06 Mpa to-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 include 2-methyl-3-butenenitrile (2M 3 BN), 2-pentenenitrile (2-PN), and the like; the isomerisation tower is a packed tower.
Further, in the step (3), the molar ratio of the catalyst, hydrocyanic acid (HCN) and 3-pentenenitrile (2-PN) is 1:40-60:60-70 during the secondary hydrocyanation.
Further, in the step (3), during the 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 comprises the step (4): and separating the materials after the secondary hydrocyanation reaction by a rectification mode to obtain Adiponitrile (ADN) and 2-methylglutaronitrile (2-MGN), and recovering the catalyst, unreacted hydrocyanic acid and 3-pentenenitrile.
In the step (4), unreacted hydrocyanic acid AND 3-pentenenitrile are recovered in sequence from materials after the secondary hydrocyanic acid reaction is finished in a rectification mode, then a catalyst is separated from the rest materials in an extraction mode, ammonia gas is introduced into a raffinate phase for reaction, the materials are centrifuged after the reaction is finished, the materials are filtered AND separated, the filtrate obtained is removed with excessive ammonia AND then subjected to negative pressure rectification, light components are separated from the top of the tower at one time, the light components comprise an extractant, 3-pentenenitrile AND m-cresol, a mixture (namely a 2-MGN/AND mixture) of Adiponitrile (ADN) AND 2-methylglutaronitrile (2-MGN) is extracted from a side line, AND an Adiponitrile (ADN) product is obtained through rectification AND separation.
Optionally, in the step (4), the operation pressure of the tower for recovering hydrocyanic acid (HCN) is less than or equal to 90kpa, the temperature of the tower top is 8-10 ℃, and the temperature of the tower bottom is 120-135 ℃, so as to control the concentration of the hydrocyanic acid (HCN) in the tower bottom to be less than 0.01%.
Optionally, in the step (4), the operation pressure of the 3-pentenenitrile recovery tower is less than or equal to 2kpa, the tower top temperature is 30-50 ℃, the tower bottom temperature is 105-125 ℃, and the temperature is preferably 110-115 ℃. In the case of recovering 3-pentenenitrile, the reaction conditions are controlled within the above-mentioned range in order to reduce the formation of by-products on the premise of meeting the separation requirements.
Optionally, in the step (4), the temperature is 50-65 ℃ during extraction, the extractant is at least one selected from cyclohexane, cyclopentane, n-hexane, n-pentane and n-heptane, and the polarity of the extractant is similar to that of the ligand and the catalyst, and the extractant can be dissolved in each other but not in 2-methylglutaronitrile and adipodinitrile, so that the extraction and separation effects are effectively achieved.
Optionally, in the step (4), after extraction, extracting agent is recovered from the extraction phase through the top of the rectifying tower, the temperature of the top of the rectifying tower is 10-25 ℃, the pressure is 5-8 Kpa, the catalyst is recovered from the bottom of the rectifying tower, and 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 can be recovered within the temperature range of 110-135 ℃ so that the catalyst can keep a good activity range.
Optionally, in the step (4), when 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.
Optionally, in the step (4), when the light components are separated from the tower top at one time by removing negative pressure rectification, the temperature of the tower top is 40-50 ℃, the temperature of the tower bottom is 160-185 ℃, and the pressure of the tower bottom is 0.5-2 Kpa, preferably 0.5-1.5 Kpa. Under the operating conditions, the content of light components in the tower kettle is effectively controlled to be less than 0.5 percent, the content of Adiponitrile (AND) in the tower kettle is controlled to be less than 1 percent, the generation of reboiling substances is reduced, AND the purity of ADN products separated in the product rectifying tower in the subsequent working procedure is 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, and the temperature is 165-170 ℃, so that the recovery rate (namely, the yield) of adiponitrile is more 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 triphenyl phosphite, tricresyl phosphite and tricresyl phosphite.
As described above, the adiponitrile production method of the invention has the following beneficial effects:
because the primary hydrocyanation and the secondary hydrocyanation are both homogeneous reactions with strong heat release, in order to ensure the heat transfer and the heat transfer effect of the reaction, reduce the reaction time and the occurrence of side reactions, the invention particularly selects a large-channel reactor and a DSR reactor as the reactors.
The method simplifies the production process flow of the 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 efficient, environment-friendly, high-yield and economical adiponitrile synthesis method, and is suitable for industrial production.
Drawings
FIG. 1 is a schematic illustration 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 representation of the flow scheme for the secondary hydrocyanation and recovery of catalyst in the adiponitrile production process of the present invention.
FIG. 4 is a schematic diagram of the rectification process flow of amino-fed products in the adiponitrile production process of the present invention.
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.
As shown in fig. 1, 2, 3 and 4, the invention provides a method for producing adiponitrile, which comprises the following steps:
(1) Primary hydrocyanation: mixing 1, 3-Butadiene (BD), hydrocyanic acid (HCN), a catalyst and a ligand, then sequentially carrying out primary hydrocyanic acid in a large-channel reactor and a DSR reactor, carrying out adiabatic flash evaporation on the materials obtained after the primary hydrocyanic acid to remove 1, 3-butadiene and most of unreacted hydrocyanic acid, and then recycling the 1, 3-butadiene and most of unreacted hydrocyanic acid to the primary hydrocyanic acid for reuse; removing residual hydrocyanic acid from the flashed material through a stripping tower, and then recycling the hydrocyanic acid to primary hydrocyanic acid for reuse; the tower bottom material after the stripping tower enters a separating tower, the tower top of the separating tower extracts materials mainly comprising 2-methyl-3-butenenitrile (2M 3 BN), the materials also comprise 2-methyl-2-butenenitrile (2M 2 BN) and 2-pentenenitrile (2 PN), 3-pentenenitrile (3-PN) is extracted from the middle side line of the tower, and the tower bottom ligand and the catalyst are used for primary hydrocyanation.
(2) Isomerization: mixing 2-methyl-3-butenenitrile (2M 3 BN) solution from primary hydrocyanation with Lewis acid, filtering after saturation to remove undissolved Lewis acid, recycling the Lewis acid, sequentially conveying filtrate and catalyst in proportion through a large-channel reactor and a DSR reactor, and carrying out isomerization treatment (firstly reacting in the large-channel reactor and then reacting in the DSR reactor) on the 2-methyl-3-butenenitrile (2M 3 BN) to convert the 2-methyl-3-butenenitrile (2M 3 BN) 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 through a large-channel reactor and a DSR reactor according to a proportion, and performing secondary hydrocyanation to generate adiponitrile (namely, reacting in the large-channel reactor firstly and then reacting in the DSR reactor); wherein the material from the isomerisation in step (2) comprises 3-pentenenitrile and a certain amount 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 the 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 controlled to be 60-160 kpa, and the total content of hydrocyanic acid and 1, 3-Butadiene (BD) is controlled to be below 2wt% (mass fraction).
Further, in the step (1), when 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 bottom 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 tower bottom 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), the temperature is controlled to be 60-100 ℃ when the 2-methyl-3-butenenitrile (2M 3 BN) solution from the primary hydrocyanation is mixed with the Lewis acid.
Further, in the step (2), the Lewis acid is selected from ZnCl 2 、ZnBr 2 、ZnI 2 、AlCl 3 、SnCl 4 、TiCl 3 At least one of Triphenylboron (TPB). The Lewis acid has the function of improving the catalytic activity of the catalyst, thereby improving the reaction speed and the selectivity of the modulation reaction.
Further, in the step (2), the amount of the Lewis acid is 0.01 to 0.2mol equivalent of 2-methyl-3-butenenitrile, and the amount of the catalyst is 0.01 to 0.02mol equivalent of 2-methyl-3-butenenitrile; the molar ratio of Lewis acid to 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 between 110 and 130 ℃. The reaction temperature is controlled near the boiling point of 2-methyl-3-butenenitrile (2M 3 BN), the catalytic activity is highest, the reaction speed is faster, and the selectivity is higher.
Further, in the step (2), after the isomerization treatment is finished, impurities are further required to be separated, and the separation method is selected from one of the following two modes:
A. conveying the material after isomerization reaction to the top of an isomerization tower, separating out a small amount of organic impurities, wherein the temperature of the tower kettle is 115-125 ℃, and the pressure is-0.06 Mpa to-0.08 Mpa;
B. and (3) carrying out low-temperature crystallization separation on the material after the isomerization reaction is finished, crystallizing in independent crystallization equipment, 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 (2M 3 BN), 2-pentenenitrile (2-PN) and the like, and the impurities are incinerated; the isomerisation tower is a packed tower.
Further, in the step (3), the molar ratio of the catalyst, hydrocyanic acid (HCN) and 3-pentenenitrile (2-PN) is 1:40-60:60-70 during the secondary hydrocyanation.
Further, in the step (3), during the 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): separating the materials after the secondary hydrocyanation reaction by 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.
In the step (4), unreacted hydrocyanic acid AND 3-pentenenitrile are recovered in sequence from materials after the secondary hydrocyanation reaction is finished in a rectification mode, then a catalyst is separated from the rest materials in an extraction mode, ammonia gas is introduced into a raffinate phase (raffinate) for reaction, the materials are centrifuged after the reaction is finished, the materials are filtered AND separated, 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 extractant, 3-pentenenitrile AND m-cresol, a mixture (namely a 2-MGN/AND mixture) of Adiponitrile (ADN) AND 2-methylglutaronitrile (2-MGN) is extracted from a side line, AND an Adiponitrile (ADN) product is obtained through rectification AND separation.
Optionally, in the step (4), the operation pressure of the tower for recovering hydrocyanic acid (HCN) is less than or equal to 90kpa, the temperature of the tower top is 8-10 ℃, and the temperature of the tower bottom is 120-135 ℃, so as to control the concentration of the hydrocyanic acid (HCN) in the tower bottom to be less than 0.01%.
Optionally, in the step (4), the operation pressure of the 3-pentenenitrile recovery tower is less than or equal to 2kpa, the tower top temperature is 30-50 ℃, the tower bottom temperature is 105-125 ℃, and the temperature is preferably 110-115 ℃. In the case of recovering 3-pentenenitrile, the reaction conditions are controlled within the above-mentioned range in order to reduce the formation of by-products on the premise of meeting the separation requirements.
Optionally, in the step (4), the temperature is 50-65 ℃ during extraction, the extractant is at least one selected from cyclohexane, cyclopentane, n-hexane, n-pentane and n-heptane, and the polarity of the extractant is similar to that of the ligand and the catalyst, and the extractant can be dissolved in each other but not in 2-methylglutaronitrile and adipodinitrile, so that the extraction and separation effects are 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, extracting agent is recovered from the extraction phase through the top of the rectifying tower, the temperature of the top of the rectifying tower is 10-25 ℃, the pressure is 5-8 Kpa, the catalyst is recovered from the bottom of the rectifying tower, and 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 can be recovered within the temperature range of 110-135 ℃ so that the catalyst can keep a good activity range.
Optionally, in the step (4), when 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.
Optionally, in the step (4), when the light components are separated from the tower top at one time by removing negative pressure rectification, the temperature of the tower top is 40-50 ℃, the temperature of the tower bottom is 160-185 ℃, and the pressure of the tower bottom is 0.5-2 Kpa, preferably 0.5-1.5 Kpa. Under the operating conditions, the content of light components in the tower kettle is effectively controlled to be less than 0.5 percent, the content of Adiponitrile (AND) in the tower kettle is controlled to be less than 1 percent, the generation of reboiling substances is reduced, AND the purity of ADN products separated in the product rectifying tower in the subsequent working procedure is 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, and the temperature is 165-170 ℃, so that the recovery rate (namely, the yield) of adiponitrile is more than 95%.
Further, in the steps (1) - (4), the catalyst consists of nickel and tri-aromatic phosphite.
Further, in the step (1), the ligand is at least one selected from triphenyl phosphite, tricresyl phosphite and tricresyl phosphite.
The following specific exemplary examples illustrate the invention in detail. It is also to be understood that the following examples are given solely for the purpose of illustration and are not to be construed as limitations upon the scope of the invention, as many insubstantial modifications and variations are within the scope of the invention as would be apparent to those skilled in the art in light of the foregoing disclosure. The specific process parameters and the like described below are also merely examples of suitable ranges, i.e., one skilled in the art can make a suitable selection from the description herein and are not intended to be limited to the specific values described below.
Example 1
The method for producing adiponitrile in this example comprises the following steps:
(1) Primary hydrocyanation: liquid 1, 3-butadiene, liquid HCN, catalyst (composed 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 mol 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 the primary hydrocyanation is controlled to be 90-100 ℃. The materials after the reaction in the large channel enter a DSR reactor, and the reaction conditions are the same as those of the reaction in the large channel.
(2) Primary hydrocyanation recovery: the material from the primary hydrocyanation is subjected to adiabatic flash evaporation to remove most of unreacted HCN and 1, 3-butadiene, 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 2wt% (mass fraction). Residual HCN is removed from the flash-evaporated material through a stripping tower, the operating pressure is 1.5-2 bar, the tower top temperature is 8-15 ℃, and the tower bottom temperature is 120-140 ℃. The material at the tower bottom after the stripping tower enters a 2-methyl-3 butenenitrile (2M 3 BN) separating tower, the temperature at the tower top of the separating tower is controlled at 35-65 ℃, the pressure is controlled at 1-10 kpa, the temperature at the tower bottom is controlled at 105-130 ℃, the material mainly comprising 2-methyl-3 butenenitrile (2M 3 BN) is extracted from the tower top of the separating tower, the material also comprises 2-methyl-2-butenenitrile (2M 2 BN) and 2-pentenenitrile (2 PN), 3-pentenenitrile (3-PN) is extracted from the side line of the tower, and the ligand and the catalyst at the tower bottom are applied to one-time hydrocyanation.
(3) IsomerismAnd (3) chemical treatment: 2-methyl-3-butenenitrile (2M 3 BN) solution from a primary cyanide with a Lewis acid ZnCl 2 (the dosage is 0.01-0.2 mol equivalent of 2-methyl-3-butenenitrile) is mixed in a reaction kettle, the temperature is controlled to be 60-100 ℃, undissolved Lewis acid is filtered after saturation, filtrate and catalyst are sequentially conveyed to a large channel reactor and a DSR reactor according to the proportion (the mol ratio of 2M3BN to catalyst is 60:1), the reaction is controlled to be 100-120 ℃, the reaction pressure is controlled to be 0.3-0.8 MPa, and 2-methyl-3-butenenitrile (2M 3 BN) is subjected to isomerization treatment, so that 2-methyl-3-butenenitrile (2M 3 BN) is converted into 3-pentenenitrile (3-PN) (namely, the 2-methyl-3-butenenitrile is reacted in the large channel reactor firstly and then is reacted in the DSR reactor, and the reaction condition of the DSR reactor is the same as that of the large channel reactor). And (3) conveying the material after the isomerization reaction to an isomerization tower by a pump, separating out a small amount of organic impurities, wherein the organic impurities comprise 2-methyl-3-butenenitrile (2M 3 BN), 2-pentenenitrile (2-PN) and the like, the temperature of a tower kettle is 115-125 ℃, the pressure is-0.06 Mpa to-0.08 Mpa, and the material in the tower kettle enters a secondary hydrocyanation reaction.
(4) Secondary hydrocyanation: mixing 3-pentenenitrile (3-PN) from the step (1) and the isomerized material from the step (3) (the isomerized material contains 3PN and catalyst) with liquid HCN and catalyst according to a ratio (the mol ratio of catalyst to HCN to 3 PN=1:50:65), sequentially conveying the mixture into a large channel reactor and an SR reactor, controlling the temperature to be 70-90 ℃ and the pressure to be about 0.4-0.5 Mpa, performing secondary hydrocyanation, and reacting to generate adiponitrile (namely, conveying the material into the large channel reactor according to a ratio by a metering pump, and then entering into a DSR reactor for reaction after the reaction is completed, wherein the reaction condition of the DSR reactor is the same as that of the large channel reactor).
(5) And (3) rectifying, separating and recycling: recovering unreacted HCN and 3-pentenenitrile from the material after the secondary hydrocyanic acid by a rectification mode, wherein the operating pressure of a HCN recovery tower is less than or equal to 90kpa, the tower top temperature is 8-10 ℃, and the tower bottom temperature is 120-130 ℃ so as to control the concentration of hydrocyanic acid (HCN) in the tower bottom to be below 0.01%; the operation pressure of the tower for recovering 3-pentenenitrile is less than or equal to 2kpa, the temperature of the tower top is 40-50 ℃, and the temperature of the tower bottom is 115-125 ℃.
Extracting and separating the rest materials to obtain a catalyst, wherein the extracting agent is cyclohexane, and the extracting temperature is controlled to be 50-65 ℃; then the extracting agent cyclohexane is recovered from the extracting phase through the top of the rectifying tower, the temperature of the top of the rectifying tower is controlled at 20-25 ℃, the pressure is 5-8 Kpa, the catalyst is recovered from the bottom of the rectifying tower, and the temperature is 110-135 ℃ and the pressure is 8-10 Kpa.
(6) Raffinate communicates with ammonia: adding the raffinate phase in the step (5) into a reaction kettle, gradually introducing ammonia gas, and controlling the reaction temperature at 45-55 ℃ and the reaction time at 60min. After the reaction is finished, the material liquid is filtered AND separated by a centrifugal machine, the obtained filter cake is subjected to solid waste removal treatment, the filtrate is subjected to negative pressure rectification after excessive ammonia is removed by nitrogen, light components (the light components comprise cyclohexane, 3PN AND m-cresol, wherein the cyclohexane is an extractant in residual materials, the m-cresol is a decomposition product in reaction materials) are separated from the tower top at one time, the temperature of the tower top is 40-50 ℃ AND the temperature of the tower bottom is 165-175 ℃ in the process, the pressure of the tower bottom is 0.5-1.5 Kpa, the content of the light components in the tower bottom is controlled to be less than 0.5%, the content of the Adiponitrile (AND) in the tower bottom is controlled to be less than 1%, AND the generation of reboiling substances is reduced.
(7) The 2-MGN/ADN mixture enters a rectifying tower for separation, 2-methylglutaronitrile (2-MGN) is extracted from the tower top, the temperature of the tower top is 150-160 ℃, adiponitrile (ADN) product is extracted from the middle part of the tower, and the temperature is 165-170 ℃. The yield of the adiponitrile is 97.8 percent through calculation and detection, and the purity of the obtained adiponitrile reaches the requirement of qualified products (purity is more than 99.5 percent).
Example 2
The method for producing adiponitrile in this example comprises the following steps:
(1) Primary hydrocyanation: liquid 1, 3-butadiene, liquid HCN, catalyst (composed of nickel and triaryl phosphite) solution and ligand (trimethoprim phosphite) are respectively conveyed to a large-channel reactor by a metering pump according to the proportion (the mol 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 the primary hydrocyanation is controlled to be 90-100 ℃. The materials after the reaction in the large channel enter a DSR reactor, and the reaction conditions are the same as those of the reaction in the large channel.
(2) Primary hydrocyanation recovery: the material from the primary hydrocyanation is subjected to adiabatic flash evaporation to remove most of unreacted HCN and 1, 3-butadiene, 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 2wt% (mass fraction). Residual HCN is removed from the flash-evaporated material through a stripping tower, the operating pressure is 1.5-2 bar, the tower top temperature is 8-15 ℃, and the tower bottom temperature is 120-140 ℃. The material at the tower bottom after the stripping tower enters a 2-methyl-3 butenenitrile (2M 3 BN) separating tower, the temperature at the tower top of the separating tower is controlled at 35-65 ℃, the pressure is controlled at 1-10 kpa, the temperature at the tower bottom is controlled at 105-130 ℃, the material mainly comprising 2-methyl-3 butenenitrile (2M 3 BN) is extracted from the tower top of the separating tower, the material also comprises 2-methyl-2-butenenitrile (2M 2 BN) and 2-pentenenitrile (2 PN), 3-pentenenitrile (3-PN) is extracted from the side line of the tower, and the ligand and the catalyst at the tower bottom are applied to one-time hydrocyanation.
(3) Isomerization: 2-methyl-3-butenenitrile (2M 3 BN) solution from a primary cyanide with a Lewis acid ZnCl 2 (the dosage is 0.1mol equivalent of 2-methyl-3-butenenitrile) is mixed in a reaction kettle, the temperature is controlled to be 60-100 ℃, undissolved Lewis acid is filtered after saturation, filtrate and catalyst are sequentially conveyed to a large-channel reactor and a DSR reactor according to the proportion (the mol ratio of 2M3BN to catalyst is 60:1), the reaction is controlled to be 120-140 ℃, the reaction pressure is controlled to be 0.3-0.8 MPa, and the isomerization treatment is carried out on 2-methyl-3-butenenitrile (2M 3 BN) to convert 2-methyl-3-butenenitrile (2M 3 BN) into 3-pentenenitrile (3-PN) (firstly, the reaction is carried out in the large-channel reactor and then the DSR reactor, and the reaction conditions of the DSR reactor are the same as those of the large-channel reactor). And (3) conveying the material after the isomerization reaction to an isomerization tower by a pump, separating out a small amount of organic impurities, wherein the organic impurities comprise 2-methyl-3-butenenitrile (2M 3 BN), 2-pentenenitrile (2-PN) and the like, the temperature of a tower kettle is 115-125 ℃, the pressure is-0.06 Mpa to-0.08 Mpa, and the material in the tower kettle enters a secondary hydrocyanation reaction.
(4) Secondary hydrocyanation: 3-pentenenitrile (3-PN) from step (1) and the isomerized material from step (3) (isomerized material contains 3PN and catalyst) are mixed with liquid HCN and catalyst in a ratio (catalyst: HCN: 3PN molar ratio=1:40:60), and then sequentially conveyed into a large channel reactor and an SR reactor, and subjected to secondary hydrocyanation at a temperature of 60-80 ℃ and a pressure of about 0.5-0.6 Mpa to produce the hexanedinitrile (firstly, the hexanedinitrile reacts in the large channel reactor and then reacts in the DSR reactor, and the reaction conditions of the DSR reactor are the same as those of the large channel reactor).
(5) And (3) rectifying, separating and recycling: recovering unreacted HCN and 3-pentenenitrile from the material after the secondary hydrocyanic acid by a rectification mode, wherein the operating pressure of a HCN recovery tower is less than or equal to 90kpa, the tower top temperature is 8-10 ℃, and the tower bottom temperature is 125-135 ℃ so as to control the concentration of hydrocyanic acid (HCN) in the tower bottom to be below 0.01%; the operation pressure of the tower for recovering 3-pentenenitrile is less than or equal to 2kpa, the temperature of the tower top is 30-40 ℃, and the temperature of the tower bottom is 110-115 ℃.
Extracting and separating the rest materials to obtain a catalyst, wherein the extracting agent is cyclohexane, and the extracting temperature is controlled to be 50-65 ℃; then the extracting agent cyclohexane is recovered from the extracting phase through the top of the rectifying tower, 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, and the temperature is 110-135 ℃ and the pressure is 6-8 Kpa.
(6) Raffinate communicates with ammonia: adding the raffinate phase in the step (5) into a reaction kettle, gradually introducing ammonia gas, and controlling the reaction temperature at 45-55 ℃ and the reaction time at 30min. After the reaction is finished, the material liquid is filtered AND separated by a centrifugal machine, the obtained filter cake is subjected to solid waste removal treatment, the filtrate is subjected to negative pressure rectification after excessive ammonia is removed by nitrogen, light components (the light components comprise cyclohexane, 3PN AND m-cresol, wherein the cyclohexane is an extractant in residual materials, the m-cresol is a decomposition product in reaction materials) are separated from the tower top at one time, the temperature of the tower top is 40-50 ℃ AND the temperature of the tower bottom is 175-185 ℃ in the process, the pressure of the tower bottom is 1-2 Kpa, the content of the light components in the tower bottom is controlled to be less than 0.5%, the content of the hexadinitrile (AND) in the tower bottom is controlled to be less than 1%, AND the generation of reboiling substances is reduced.
(7) The 2-MGN/ADN mixture enters a rectifying tower for separation, 2-methylglutaronitrile (2-MGN) is extracted from the tower top, the temperature of the tower top is 150-160 ℃, adiponitrile (ADN) product is extracted from the middle part of the tower, and the temperature is 165-170 ℃. The yield of the obtained dinitrile is 97.2 percent through calculation and detection, and the purity of the obtained dinitrile reaches the requirement of qualified products (purity is more than 99.7 percent).
Example 3
The method for producing adiponitrile in this example comprises the following steps:
(1) Primary hydrocyanation: liquid 1, 3-butadiene, liquid HCN, catalyst (composed of nickel and triaryl phosphite) solution and ligand (tri-p-toluylene phosphite) are respectively conveyed to a large channel reactor by a metering pump according to the proportion (the mol ratio of 1, 3-butadiene to HCN to catalyst to 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 the primary hydrocyanation is controlled to be 90-100 ℃. The materials after the reaction in the large channel enter a DSR reactor, and the reaction conditions are the same as those of the reaction in the large channel.
(2) Primary hydrocyanation recovery: the material from the primary hydrocyanation is subjected to adiabatic flash evaporation to remove most of unreacted HCN and 1, 3-butadiene, 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 2wt% (mass fraction). Residual HCN is removed from the flash-evaporated material through a stripping tower, the operating pressure is 1.5-2 bar, the tower top temperature is 8-15 ℃, and the tower bottom temperature is 120-140 ℃. The material at the tower bottom after the stripping tower enters a 2-methyl-3 butenenitrile (2M 3 BN) separating tower, the temperature at the tower top of the separating tower is controlled at 35-65 ℃, the pressure is controlled at 1-10 kpa, the temperature at the tower bottom is controlled at 105-130 ℃, the material mainly comprising 2-methyl-3 butenenitrile (2M 3 BN) is extracted from the tower top of the separating tower, the material also comprises 2-methyl-2-butenenitrile (2M 2 BN) and 2-pentenenitrile (2 PN), 3-pentenenitrile (3-PN) is extracted from the side line of the tower, and the ligand and the catalyst at the tower bottom are applied to one-time hydrocyanation.
(3) Isomerization: 2-methyl-3-butenenitrile (2M 3 BN) solution from a primary cyanide with a Lewis acid ZnCl 2 (the dosage is 0.01-0.2 mol equivalent of 2-methyl-3-butenenitrile) is mixed in a reaction kettle, the temperature is controlled to be 60-100 ℃, undissolved Lewis acid is filtered after saturation, and filtrate and catalyst are sequentially conveyed through a large channel for reaction according to the proportion (the mol ratio of 2M3BN to catalyst is 60:1)In the reactor and the DSR reactor, the reaction is controlled at 125-145 ℃, the reaction pressure is controlled at 0.3-0.8 MPa, the isomerization treatment is carried out on the 2-methyl-3-butenenitrile (2M 3 BN), so that the 2-methyl-3-butenenitrile (2M 3 BN) is converted into 3-pentenenitrile (3-PN) (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). Separating a small amount of organic impurities including 2-methyl-3-butenenitrile (2M 3 BN), 2-pentenenitrile (2-PN) and the like by adopting a low-temperature crystallization separation mode on the material after the isomerization reaction is finished, controlling the temperature to be 20-70 ℃ and the pressure to be normal pressure, and enabling the material at the tower bottom to enter a secondary hydrocyanation reaction.
(4) Secondary hydrocyanation: 3-pentenenitrile (3-PN) from step (1) and the isomerized material from step (3) (isomerized material contains 3PN and catalyst) are mixed with liquid HCN and catalyst in a ratio (catalyst: HCN: 3PN molar ratio=1:55:70), and then sequentially conveyed into a large channel reactor and an SR reactor, and subjected to secondary hydrocyanation at a temperature of 70-80 ℃ and a pressure of about 0.6-0.8 Mpa to produce adiponitrile (firstly, reacted in the large channel reactor and then reacted in the DSR reactor, wherein the reaction condition of the DSR reactor is the same as that of the large channel reactor).
(5) And (3) rectifying, separating and recycling: recovering unreacted HCN and 3-pentenenitrile from the material after the secondary hydrocyanic acid by a rectification mode, wherein the operating pressure of a HCN recovery tower is less than or equal to 90kpa, the tower top temperature is 8-10 ℃, and the tower bottom temperature is 120-130 ℃ so as to control the concentration of hydrocyanic acid (HCN) in the tower bottom to be below 0.01%; the operation pressure of the tower for recovering 3-pentenenitrile is less than or equal to 2kpa, the temperature of the tower top is 35-45 ℃, and the temperature of the tower bottom is 105-115 ℃.
Extracting and separating the rest materials to obtain a catalyst, wherein the extracting agent is cyclohexane, and the extracting temperature is controlled to be 50-65 ℃; then the extracting agent cyclohexane is recovered from the extracting phase through the top of the rectifying tower, the temperature of the top of the rectifying tower is controlled at 15-20 ℃, the pressure is 5-8 Kpa, the catalyst is recovered from the bottom of the rectifying tower, and the temperature is 110-135 ℃ and the pressure is 6-8 Kpa.
(6) Raffinate communicates with ammonia: adding the raffinate phase in the step (5) into a reaction kettle, gradually introducing ammonia gas, and controlling the reaction temperature at 45-55 ℃ and the reaction time at 120min. After the reaction is finished, the material liquid is filtered AND separated by a centrifugal machine, the obtained filter cake is subjected to solid waste removal treatment, the filtrate is subjected to negative pressure rectification after excessive ammonia is removed by nitrogen, light components (the light components comprise cyclohexane, 3PN AND m-cresol, wherein the cyclohexane is an extractant in residual materials, the m-cresol is a decomposition product in reaction materials) are separated from the tower top at one time, the temperature of the tower top is 40-50 ℃ AND the temperature of the tower bottom is 170-185 ℃ in the process, the pressure of the tower bottom is 0.5-2 Kpa, the content of the light components in the tower bottom is controlled to be less than 0.5%, the content of the Adiponitrile (AND) in the tower bottom is controlled to be less than 1%, AND the generation of reboiling substances is reduced.
(7) The 2-MGN/ADN mixture enters a rectifying tower for separation, 2-methylglutaronitrile (2-MGN) is extracted from the tower top, the temperature of the tower top is 150-160 ℃, adiponitrile (ADN) product is extracted from the middle part of the tower, and the temperature is 165-170 ℃. The yield of the adiponitrile is 95.9 percent through calculation and detection, and the purity of the obtained adiponitrile reaches the requirement of qualified products (purity is more than 99.8 percent).
Example 4
The method for producing adiponitrile in this example comprises the following steps:
(1) Primary hydrocyanation: liquid 1, 3-butadiene, liquid HCN, catalyst (composed of nickel and triaryl phosphite) solution and ligand (triphosphite) are respectively conveyed to a large-channel reactor by a metering pump according to the proportion (the mol ratio of 1, 3-butadiene to HCN to catalyst to 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 the primary hydrocyanation is controlled to be 90-100 ℃. The materials after the reaction in the large channel enter a DSR reactor, and the reaction conditions are the same as those of the reaction in the large channel.
(2) Primary hydrocyanation recovery: the material from the primary hydrocyanation is subjected to adiabatic flash evaporation to remove most of unreacted HCN and 1, 3-butadiene, 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 2wt% (mass fraction). Residual HCN is removed from the flash-evaporated material through a stripping tower, the operating pressure is 1.5-2 bar, the tower top temperature is 8-15 ℃, and the tower bottom temperature is 120-140 ℃. The material at the tower bottom after the stripping tower enters a 2-methyl-3 butenenitrile (2M 3 BN) separating tower, the temperature at the tower top of the separating tower is controlled at 35-65 ℃, the pressure is controlled at 1-10 kpa, the temperature at the tower bottom is controlled at 105-130 ℃, the material mainly comprising 2-methyl-3 butenenitrile (2M 3 BN) is extracted from the tower top of the separating tower, the material also comprises 2-methyl-2-butenenitrile (2M 2 BN) and 2-pentenenitrile (2 PN), 3-pentenenitrile (3-PN) is extracted from the side line of the tower, and the ligand and the catalyst at the tower bottom are applied to one-time hydrocyanation.
(3) Isomerization: 2-methyl-3-butenenitrile (2M 3 BN) solution from a primary cyanide with a Lewis acid ZnCl 2 (the dosage is 0.01-0.2 mol equivalent of 2-methyl-3-butenenitrile) is mixed in a reaction kettle, the temperature is controlled to be 60-100 ℃, undissolved Lewis acid is filtered after saturation, filtrate and catalyst are sequentially conveyed to a large channel reactor and a DSR reactor according to the proportion (the mol ratio of 2M3BN to catalyst is 60:1), the reaction is controlled to be 135-145 ℃, the reaction pressure is controlled to be 0.3-0.8 MPa, and 2-methyl-3-butenenitrile (2M 3 BN) is subjected to isomerization treatment, so that 2-methyl-3-butenenitrile (2M 3 BN) is converted into 3-pentenenitrile (3-PN) (firstly, the 2-methyl-3-butenenitrile is reacted in the large channel reactor and then is reacted in the DSR reactor, and the reaction condition of the DSR reactor is the same as that of the large channel reactor). And (3) conveying the material after the isomerization reaction to an isomerization tower by a pump, separating out a small amount of organic impurities, wherein the organic impurities comprise 2-methyl-3-butenenitrile (2M 3 BN), 2-pentenenitrile (2-PN) and the like, the temperature of a tower kettle is 115-125 ℃, the pressure is-0.06 Mpa to-0.08 Mpa, and the material in the tower kettle enters a secondary hydrocyanation reaction.
(4) Secondary hydrocyanation: 3-pentenenitrile (3-PN) from step (1) and the isomerized material from step (3) (isomerized material contains 3PN and catalyst) are mixed with liquid HCN and catalyst in a ratio (catalyst: HCN: 3PN molar ratio=1:60:60), and then sequentially conveyed into a large channel reactor and an SR reactor, and subjected to secondary hydrocyanation at a temperature of 60-80 ℃ and a pressure of about 0.5-0.7 Mpa to produce adiponitrile (firstly, reacted in the large channel reactor and then reacted in the DSR reactor, wherein the reaction condition of the DSR reactor is the same as that of the large channel reactor).
(5) And (3) rectifying, separating and recycling: recovering unreacted HCN and 3-pentenenitrile from the material after the secondary hydrocyanic acid by a rectification mode, wherein the operating pressure of a HCN recovery tower is less than or equal to 90kpa, the tower top temperature is 8-10 ℃, and the tower bottom temperature is 125-135 ℃ so as to control the concentration of hydrocyanic acid (HCN) in the tower bottom to be below 0.01%; the operation pressure of the tower for recovering 3-pentenenitrile is less than or equal to 2kpa, the temperature of the tower top is 40-50 ℃, and the temperature of the tower bottom is 110-120 ℃.
Extracting and separating the rest materials to obtain a catalyst, wherein the extracting agent is cyclohexane, and the extracting temperature is controlled to be 50-65 ℃; then the extracting agent cyclohexane is recovered from the extracting phase through the top of the rectifying tower, the temperature of the top of the rectifying tower is controlled at 15-20 ℃, the pressure is 5-8 Kpa, the catalyst is recovered from the bottom of the rectifying tower, and the temperature is 110-135 ℃ and the pressure is 8-10 Kpa.
(6) Raffinate communicates with ammonia: adding the raffinate phase in the step (5) into a reaction kettle, gradually introducing ammonia gas, and controlling the reaction temperature to be 45-55 ℃ and the reaction time to be 100min. After the reaction is finished, the material liquid is filtered AND separated by a centrifugal machine, the obtained filter cake is subjected to solid waste removal treatment, the filtrate is subjected to negative pressure rectification after excessive ammonia is removed by nitrogen, light components (the light components comprise cyclohexane, 3PN AND m-cresol, wherein the cyclohexane is an extractant in residual materials, the m-cresol is a decomposition product in reaction materials) are separated from the tower top at one time, the temperature of the tower top is 40-50 ℃ AND the temperature of the tower bottom is 165-175 ℃ in the process, the pressure of the tower bottom is 0.5-1.5 Kpa, the content of the light components in the tower bottom is controlled to be less than 0.5%, the content of the Adiponitrile (AND) in the tower bottom is controlled to be less than 1%, AND the generation of reboiling substances is reduced.
(7) The 2-MGN/ADN mixture enters a rectifying tower for separation, 2-methylglutaronitrile (2-MGN) is extracted from the tower top, the temperature of the tower top is 150-160 ℃, adiponitrile (ADN) product is extracted from the middle part of the tower, and the temperature is 165-170 ℃. The yield of the adiponitrile is 96.5 percent through calculation and detection, and the purity of the obtained adiponitrile reaches the requirement of qualified products (purity is more than 99.6 percent).
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.
Claims (7)
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 materials obtained after primary hydrocyanation to remove 1, 3-butadiene and most of unreacted hydrocyanic acid, removing residual hydrocyanic acid from the materials obtained after flash evaporation through a stripping tower, feeding the materials at the tower bottom after the stripping tower into a separation tower, extracting materials mainly comprising 2-methyl-3-butenenitrile from the tower top of the separation tower, extracting 3-pentenenitrile from the side line of the tower, and applying the ligand and the catalyst to primary hydrocyanation;
(2) Isomerization: mixing 2-methyl-3-butenenitrile solution from primary hydrocyanation with Lewis acid, filtering to remove undissolved Lewis acid after saturation, sequentially conveying filtrate and catalyst in proportion through a large-channel reactor and a DSR reactor, and carrying out isomerization treatment on 2-methyl-3-butenenitrile to convert 2-methyl-3-butenenitrile into 3-pentenenitrile;
after the isomerization treatment is finished, impurities are also required 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 out a small amount of organic impurities, wherein the temperature of the tower kettle is 105-125 ℃, and the pressure is-0.1 Mpa to-0.01 Mpa;
B. 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;
the organic impurities comprise 2-methyl-3-butenenitrile and 2-pentenenitrile;
(3) Secondary hydrocyanation: sequentially conveying 3-pentenenitrile from the step (1), material isomerized from the step (2), hydrocyanic acid and a catalyst through a large-channel reactor and a DSR reactor according to a proportion, and performing secondary hydrocyanation to generate adiponitrile; wherein the material from step (2) isomerisation comprises 3-pentenenitrile and catalyst;
(4) Sequentially recovering unreacted hydrocyanic acid and 3-pentenenitrile from materials after secondary hydrocyanic acid reaction in a rectification mode, separating a catalyst from the rest materials in an extraction mode, introducing ammonia gas into a raffinate phase for reaction at a reaction temperature of 45-55 ℃ for 30-120 min, centrifuging the materials after the reaction is finished, filtering and separating, removing excessive ammonia from the obtained filtrate, removing negative pressure rectification, and separating light components from the top of the tower at one time, wherein the light components comprise an extractant, 3-pentenenitrile and m-cresol, extracting a mixture of adiponitrile and 2-methylglutaronitrile from a side line, and rectifying and separating to obtain an adiponitrile product;
when the light components are separated from the tower top at one time by removing negative pressure rectification, the temperature of the tower top is 40-50 ℃, the temperature of the tower bottom is 160-185 ℃, and the pressure of the tower bottom is 0.5-2 Kpa.
2. The method according to claim 1, characterized in that: 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 controlled to be 60-160 kpa;
And/or, in the step (1), when 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 bottom 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 to the hydrocyanic acid to the catalyst to the ligand is 100-500:90-400:1:20-100.
3. The method according to claim 1, characterized in that: in the step (2), when the 2-methyl-3-butenenitrile solution from the 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 ZnCl 2 、ZnBr 2 、ZnI 2 、AlCl 3 、SnCl 4 、TiCl 3 At least one of Triphenylboron (TPB);
and/or, in the step (2), the Lewis acid is used in an amount of 0.01 to 0.2mol equivalent of 2-methyl-3-butenenitrile, and the catalyst is used in an amount of 0.01 to 0.02mol equivalent of 2-methyl-3-butenenitrile; the molar ratio of Lewis acid to 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 controlled to be 0.3-0.8 MPa.
4. The method according to claim 1, characterized in that: in the step (3), the molar ratio of the catalyst, hydrocyanic acid (HCN) and 3-pentenenitrile (2-PN) is 1 during the secondary hydrocyanation: 40-60:60-70;
and/or, in the step (3), during the secondary hydrocyanation, the reaction temperature is controlled to be 60-90 ℃ and the pressure is controlled to be 0.4-0.8 Mpa.
5. The method according to claim 1, characterized in that: in the step (4), the operation pressure of the recovered hydrocyanic acid tower is less than or equal to 90kpa, the temperature of the tower top is 8-10 ℃, and the temperature of the tower bottom is 120-135 ℃ so as to control the hydrocyanic acid concentration of the tower bottom to be below 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 tower top is 30-50 ℃, and the temperature of the tower bottom is 105-125 ℃;
and/or in the step (4), the temperature is 50-65 ℃ during extraction, and the extractant is at least one selected from cyclohexane, cyclopentane, n-hexane, n-pentane and n-heptane;
and/or, in the step (4), extracting, recovering the extractant from the extract phase through the top of the rectifying tower, wherein the temperature of the top of the rectifying tower is 10-25 ℃, the pressure is 5-8 Kpa, the catalyst is recovered from the bottom of the rectifying tower, and the temperature is 110-135 ℃ and the pressure is 6-10 Kpa.
6. The method according to claim 1, characterized in that:
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 of the tower, and the temperature is 165-170 ℃.
7. The method according to claim 1, characterized in that: in the steps (1) - (4), the catalyst consists of nickel and triaryl phosphite;
and/or, in the step (1), the ligand is selected from at least one of triphenyl phosphite, tricresyl phosphite and tricresyl phosphite.
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| CN103739516A (en) * | 2014-01-06 | 2014-04-23 | 重庆中平紫光科技发展有限公司 | Method for synthesizing adiponitrile by isomerization liquid of 2-methyl-3-crotononitrile |
| CN105531257A (en) * | 2013-07-17 | 2016-04-27 | 因温斯特技术公司 | Separating a solvent from a nickel catalyst by distillation |
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| CN105531257A (en) * | 2013-07-17 | 2016-04-27 | 因温斯特技术公司 | Separating a solvent from a nickel catalyst by distillation |
| CN103739516A (en) * | 2014-01-06 | 2014-04-23 | 重庆中平紫光科技发展有限公司 | Method for synthesizing adiponitrile by isomerization liquid of 2-methyl-3-crotononitrile |
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