CN109748822B - Method and system for preparing isocyanate monomer - Google Patents
Method and system for preparing isocyanate monomer Download PDFInfo
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- CN109748822B CN109748822B CN201711091092.9A CN201711091092A CN109748822B CN 109748822 B CN109748822 B CN 109748822B CN 201711091092 A CN201711091092 A CN 201711091092A CN 109748822 B CN109748822 B CN 109748822B
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Abstract
The invention discloses a method and a system for preparing isocyanate, wherein the method comprises the steps of continuously adding amine hydrochloride and phosgene into a reaction kettle, controlling the reaction temperature, gasifying generated isocyanate, HCl, acyl chloride and the like, then feeding the gasified isocyanate, HCl, acyl chloride and the like into an intermediate product kettle, condensing the intermediate product such as the acyl chloride and the like after the gas passes through a condenser, participating in a neutralization reaction, reacting the acyl chloride into the isocyanate through organic base catalysis, and then separating to obtain a pure product. And phosgene and HCl enter a secondary condensation stage, and phosgene is condensed to the reaction kettle for recycling. Compared with the traditional cracking process, the method has the advantages of stable system control, high yield, low energy consumption and less equipment investment. Meanwhile, cracking procedures are reduced, a cracker does not need to be cleaned, and material leakage and personnel safety risks are reduced.
Description
Technical Field
The present invention relates to a method and system for preparing isocyanate monomer, more specifically, to a method and system for preparing isocyanate by phosgenation reaction.
Background
Phosgenation processes for the preparation of individual isocyanates by reacting primary organic amines with phosgene in inert solvents are known from the prior art.
The patent publication CN 102659631A reports that ethyl isocyanate is prepared by a one-step method, triphosgene and ethylamine hydrochloride are used as raw materials, xylene is used as a solvent, a catalyst is added, the mixture is heated to over 135 ℃ for reaction, and the reaction degree is analyzed by a central control method; the separation process adopts rectification (tower plate 40), the acid gas is removed by heating to reflux, and then the target product with the temperature of 50-70 ℃ is received, the purity of the obtained product is more than 99%, and the yield is 87%. From the description of this patent, many problems can be found, including the influence of long-time high-temperature heating on heat-sensitive products, no mention of acid chloride problems, high fraction collection temperature, product purity test method and yield, etc.
On the other hand, many patents and documents on the synthesis of methyl isocyanate are mainly the phosgene method route.
MIC (methyl isocyanate) was earlier studied by dupont, and reports on MIC production by non-phosgene method and phosgene method were made in 60 and 70 s. Patent US4082787 reports the MIC of methylamine with phosgene at 240-250 ℃, but the MIC is equilibrium with HCl to MCC (carbamoyl chloride). In order to promote the conversion of MCC into MIC, a kettle type cracking process is used, 40% of MCC solution is introduced into a decomposition kettle at 100 ℃ for distillation, and high-concentration MIC, MCC and toluene obtained after primary condensation (the influence of the heat exchange area on the ratio of MIC to MCC) enter a rectifying tower to realize separation.
At present, the main route in MIC is that phosgene and methylamine are respectively metered and preheated, then enter a reactor to synthesize MCC and are mixed with a circulating solvent, and enter an MCC decomposition reactor to generate MIC; MIC and solvent flow into a primary distillation tower through condensation, and the solvent and the undecomposed MCC overflow from a tower kettle and need to be dissolved before returning to the MCC decomposition reactor; MIC and partial solvent extracted from the top of the primary distillation tower enter a rectifying tower, MIC is extracted from the top of the tower, and the solvent is extracted from the bottom of the tower and returned to the MCC decomposition reactor. And (3) performing secondary heating decomposition, performing secondary condensation, then separating in a rectifying tower to obtain a product MIC at the tower top, and returning the solvent in the tower kettle to the mixing tank for continuous use.
In the production of methyl isocyanate, the yield and unit cost of MIC are directly related to the amount of by-products generated in the main equipment, which generally exist in the form of solid insoluble in solvent, and through theoretical analysis, the authors have studied the degree of influence of various factors on the generation of by-products to improve the yield of MIC and reduce the unit product cost.
The study on the amount of by-produced products in the production of methyl isocyanate by Hubei Shalong Dada (Jingzhou) pesticide chemical Co., Ltd indicates that: n-methyl carbamyl chloride (CH3NHCOCl, MCC for short) is mixed with a solvent, and then enters a rectifying tower for separation after secondary decomposition and secondary condensation, a product MIC is obtained at the tower top, a tower kettle solvent flows back to a mixing tank for use, the material quantity entering a primary decomposer and the jacket steam pressure are controlled by an automatic control instrument, and the constant flow is maintained. 3.1 to reduce the amount of by-products in MIC production, the temperature of the mixing tank is controlled within the following range, the MCC mass fraction in the mixing tank is 15%, and the service life of the primary decomposer is 96 h. Using this technique, Jingzhou pesticide chemical Co., Ltd, the average yield of MIC increased from 86.2% to 89.2%.
MIC formed by decomposition in the cracking process cannot escape in time and is easy to form tripolymer, and the tripolymer is attached to the wall of a condensation pipe, so that the wall of the condensation pipe needs to be cleaned frequently, the health of workers is damaged, and the production cannot be continuously carried out, so that economic loss is caused.
In addition, HCL generated by cracking cannot escape in time, is easy to react with MIC to generate MCC, and has certain corrosivity to a reaction kettle.
In addition, the invention patent CN201510705468.5 relates to a synthesis method (BDI) of n-butyl isocyanate, Anhui Guangxi agriculture chemical Co. The process will face the following problems in production scale-up: (1) the isocyanate is prepared by using an azide method, the reaction yield is about 90-93%, the purity is less than 98.5%, and the yield is lower than the photochemical conversion rate and the yield; (2) the first step uses thionyl chloride, which causes serious pollution, and the second step uses azide, which has high danger; (3) the cost of the thionyl chloride and the sodium azide is 8-10 times of that of phosgene, and the economy is poor; (4) the reaction is completed in 2 steps, the intermediate product needs to be treated by reduced pressure distillation, and the process is relatively complex.
The prior patent reports more methods for preparing isocyanate by pyrolyzing aminoalkyl esters by non-phosgene method, but the methods are still in the research stage in general. In the processes for preparing isocyanate by pyrolyzing aminoalkyl esters reported in U.S. Pat. Nos. 6639101, 5449817, 5326903 and 5914428, etc., continuous pyrolysis processes are adopted, the concentration of the aminoalkyl esters in the reaction system is very low, generally only 0.1% -8%, while the concentrations of the used solvent and the carrier are as high as more than 92%, the continuous pyrolysis process is complex to operate, the content of diisocyanate is low, the intermediate monoisocyanate is difficult to recycle, the energy consumption is high, the recovery cost of the heat carrier is high, the process has no economic advantages, and the industrial production is difficult to realize.
Other phosgene routes can be divided into gas-phase processes, which produce the corresponding isoamino acid esters by direct reaction of primary amines with phosgene, and into cold and hot phosgene, EP2060560a1, US4847408, US 551935, US 563396; the gas phase phosgenation routes are described in a large number of patents such as US6082891, US6264900, US6225497, EP0758918, US6800781, US6225497 DE10238995 and the like, which have the advantage of fast reaction speed, but require high temperature phosgenation reaction, require high energy consumption systems such as molten salt and the like, and the overall investment is large, while the traditional salt formation photochemical and cold and hot photochemical are described in a large number of patents such as EP0384463, US4922005, US4663473, CN101203488, CN201310180725.9 and the like, and the liquid phase method mainly comprises the steps of firstly reacting corresponding amine with acid gas such as hydrogen chloride, carbon dioxide and the like to prepare amine salt, then reacting the amine salt with phosgene, and the overall reaction in a reaction kettle, and polymerizing the produced NCO group in a liquid phase to produce high molecular impurities such as uretonimine, multimer and the like, and the energy consumption is relatively high.
In addition, CN10173511 introduces a process for preparing isocyanate by using thionyl chloride and sodium azide, the used raw materials have high cost, and SO is generated2The tail gas is difficult to treat, and the danger of azide is high.
To overcome the above technical problems, the present invention relates to a method for preparing isocyanate monomers, and more particularly, to a method for preparing isocyanates in a phosgenation reaction.
The invention aims to solve the problems of low yield and low conversion rate of diisocyanate synthesized by continuous thermal decomposition of isocyanate, and provides a process system integrating synthesis, separation and purification, which has the advantages of simple flow, high reaction efficiency, mild conditions, short reaction time, easy separation and high product quality, cyclic use of byproducts and solvents, environment-friendly process and the like.
Disclosure of Invention
Phosgenation processes for the preparation of individual isocyanates by reacting primary organic amines with phosgene in inert solvents are known from the prior art. The technical problem to be solved by the invention is to provide a process for preparing an isocyanate monomer, which can overcome the technical problems of long process, more side reactions, high energy consumption and low yield of the traditional process. Aiming at the defects of the traditional process, the improved process comprises the following steps:
the process for preparing isocyanates according to the invention comprises the following steps:
(A) adding amine hydrochloride and phosgene serving as raw materials into a reaction kettle, and carrying out a photochemical reaction in the presence of a solvent to obtain a reaction product of carbamoyl chloride and isocyanate gas;
(B) and (2) carrying out gas-liquid separation on the reaction product of the carbamyl chloride and the isocyanate gas, removing uncondensed phosgene and hydrogen chloride, and enabling the separated liquid to enter a static mixer and react with a solvent in a ratio of 1: 1-30 mass ratio, preferably 1: 2-15 mass ratio, then mixing, conveying to a neutralization reactor, and carrying out neutralization reaction with a neutralizer to obtain slurry reaction liquid;
(C) and (C) carrying out solid-liquid separation on the reaction liquid obtained in the step (B), and sending the separated isocyanate-containing liquid into a rectification system for rectification separation to obtain an isocyanate product.
Further, in the step (B), the uncondensed phosgene and hydrogen chloride are sent to a phosgene absorption process for absorption and recycling, and HCl is absorbed by water to generate hydrochloric acid as a byproduct.
Further, in the step (C), the solid-liquid separation comprises filtering the reaction solution obtained in the step (B) by a filter (preferably a rotary filter), then carrying out solid-liquid separation by centrifugation (preferably high-speed centrifugation), and recycling the separated solid salt after the neutralization agent recovery step.
Further, in the step (C), excessive neutralizing agent and solvent are obtained through rectification separation, and the neutralizing agent and the solvent are recycled.
Further, the reaction heat of the neutralization reaction is exchanged by a subsequent heat exchanger.
The raw material amine is preferably a mono-or bifunctional or higher chain aliphatic amine or cyclic aliphatic amine having a primary amine group.
Preferably, the first step is a liquid-phase photochemical reaction which is conventional in the field, the reaction kettle is firstly added with a part of solvent, and the solvent accounting for 5-95% of the total reaction mass (comprising the solvent, phosgene and amine or hydrochloride of amine) is added, and the solvent accounting for 60-90% of the total reaction mass is preferably added. Usually, the reaction temperature is 50-160 ℃, the reaction time is 1-25 hours, and the reaction pressure is 0.1-10 kgf/cm2Preferably, the reaction pressure is 1 to 5kgf/cm2。
The molar ratio of the phosgene to the amine or the hydrochloride of the amine is 1.1-5: 1, preferably 1.2-3: 1, and more preferably 1.5-2: 1.
Preferably, the temperature of the treatment for removing phosgene and hydrogen chloride by condensation in step (B) is 10 to 130 ℃, preferably 20 to 60 ℃.
The solvent is an inert liquid medium, and is selected from one or more of petroleum ether, cyclohexane, n-hexane, mixed xylene, o-xylene, m-xylene, p-xylene, toluene, benzene xylene, 1, 2-dichloroethane, carbon tetrachloride, chlorobenzene, o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, monochlorobiphenyl, bromobenzene, ethyl acetate, propyl acetate, amyl acetate, isoamyl acetate, butyl acetate, isobutyl acetate, phenyl acetate, ethyl propionate, propyl propionate, amyl propionate, isoamyl propionate, butyl propionate, isobutyl propionate, amyl formate, ethyl isovalerate, dibutyl ester, tetrahydrofuran, ethylene glycol dimethyl ester, anisole and cyclohexanone, and can be mixed and used according to any proportion; chlorobenzene or o-dichlorobenzene (ODCB) is preferred as solvent in the present invention.
The prepared isocyanate monomer is one or a mixture of two or more of toluene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, methylcyclohexyl diisocyanate, hydrogenated MDI, isophorone diisocyanate, p-phenylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, methyl isocyanate, ethyl isocyanate and butyl isocyanate according to any proportion, and preferably methyl isocyanate and ethyl isocyanate.
Preferably, the amino acid chloride and neutralizing agent removed phosgene and HCl in step (B) flow rapidly through the static mixer for neutralization, and the neutralizing agent is pyridine, imidazole, triethylamine, etc., preferably triethylamine or methylimidazole.
The feeding molar ratio of the neutralizing agent to the carbamoyl chloride is preferably 1 to 5:1, preferably 1.1 to 2:1, and the conversion of the amine salt-forming reaction can be kept high, and if the equivalent ratio is 4 or less, it is economically advantageous. Because the salt-forming reaction is a rapid reaction, the concentration of the hydrochloride gradually increases, and the viscosity of the reaction emulsion is sharply increased due to excessively high concentration, so that incomplete salt-forming reaction is easy to occur, and the separation effect is further influenced. The invention uses a continuous process, does not need high-power reinforced dispersion stirring of kettle type reaction, has low energy consumption, and can not form large particles and large blocks of precipitates of the kettle type reaction, thereby blocking a pipeline valve and simultaneously causing the defect of low conversion rate of subsequent reaction. The usage amount of the neutralizer can be greatly reduced, and the process control is stable. The unreacted neutralizer and the reaction liquid are separated by a three-in-one machine, namely a filtering/washing/drying machine, and the filtrate is sent to a separation process for rectification. And (4) carrying out centrifugal filtration, washing and drying on the solid salt, and then carrying out recovery treatment.
Controlling the ratio of the total feeding amount, wherein the concentration of the hydrochloride of the neutralizing agent contained in the slurry reaction liquid in the step (B) is between 1 and 30 percent by weight, preferably between 5 and 20 percent by weight; the residence time of the neutralization reaction is 1-60 seconds, preferably 3-15 seconds. Therefore, the high-temperature retention time of the materials can be reduced, the product purity is high, the energy consumption of separation is reduced in the subsequent separation process, and the production efficiency and the economic benefit are greatly improved.
After the neutralization and salt forming reaction, heat exchange is carried out through a heat exchanger, and heat exchange is carried out by using chilled water, so that the reaction temperature is controlled, and during the whole reaction period, the temperature is controlled between 10 ℃ and 70 ℃, and preferably controlled between 20 ℃ and 50 ℃.
And filtering the neutralized solution by using filtering equipment, wherein the filtering diameter is 1-100 mu m, and preferably 10-25 mu m. The filtering equipment is preferably a centrifugal filter, and the rotating speed is 50-2000 rpm, and preferably 300-500 rpm.
And (3) sending the separated isocyanate-containing filtrate into a rectification system for rectification separation, controlling the extraction temperature of the tower to be 30-100 ℃, and obtaining an isocyanate product, an excessive neutralizing agent and a solvent through a tower top condenser, wherein the isocyanate product, the excessive neutralizing agent and the solvent are respectively sent to a neutralizing agent tank, a solvent tank and a product tank, and the neutralizing agent and the solvent are recycled. The tail gas is sent to a tail gas treatment process. The subsequent production steps are conventional isocyanate monomer preparation methods in the art. The separation pressure is controlled to be 1-150 kpa (absolute pressure), preferably 50-120 kpa (absolute pressure), the top temperature of the rectifying tower is about 20-150 ℃, preferably 30-80 ℃, and the bottom operating temperature is 30-200 ℃, preferably 50-160 ℃.
The present invention further provides a system for preparing isocyanates, the system comprising: a photochemical reaction kettle, a gas-liquid separator, a reaction gas phase condenser, a mixer (preferably a static mixer), a continuous neutralization reactor, a neutralization reaction heat exchanger, a filtering/washing/drying integrated machine and a rectifying tower,
the outlet of the photochemical reaction kettle is connected with the inlet of the gas-liquid separator, the gas outlet of the gas-liquid separator is connected with the inlet of the reaction gas phase condenser, the liquid outlet of the reaction gas phase condenser is connected with the inlet of the mixer (static mixer), the outlet of the mixer (static mixer) is connected with the inlet of the continuous neutralization reactor, the outlet of the continuous neutralization reactor is connected with the neutralization reaction heat exchanger, the neutralization reaction heat exchanger is further connected with the inlet of the filtering/washing/drying integrated machine, and the liquid outlet of the filtering/washing/drying integrated machine is connected with the rectifying tower.
Further, a solid outlet of the filtering/washing/drying integrated machine is connected with a neutralizer collecting tank through a neutralization salt recovery processing device.
Further, a tail gas outlet of the rectifying tower top condenser is connected to a tail gas treatment device, and/or the rectifying tower top condenser is respectively connected with a neutralizer collecting tank, a solvent collecting tank and an isocyanate product tank.
Further, the neutralizer collecting tank is connected to the continuous neutralization reactor through a pipeline, and the solvent collecting tank is connected to the static mixer and/or the photochemical reaction kettle through a pipeline.
The invention has the beneficial effect of developing a stable-control reaction process for preparing isocyanate. Compared with the prior art, the beneficial effects of the invention are mainly embodied in the following aspects:
1. the first step reaction of the invention is different from the conventional liquid phase phosgene method, triphosgene and other processes, and synthesized intermediates such as isocyanate, acyl chloride and the like are extracted from gas phase, so that side reactions such as high polymerization, molecular cracking and the like caused by high temperature retention of materials and NCO groups are avoided.
2. The traditional high-temperature cracking process is not adopted, the yield of isocyanate is high, the generated trimer and other high molecular impurities are less, the production efficiency is improved, and the product quality is stable.
3. Compared with other reaction methods, the method does not need to clean a cracking kettle or a cracking tube, reduces the material leakage risk and the three wastes, and prevents the leakage of toxic gas and the environmental pollution.
4. The process is relatively simple, the occupied area of equipment is small, and the total investment is less. The materials are recycled, no cracking waste is generated, and the three wastes are less.
5. The process flow provided by the invention has the characteristics of simple process, easy implementation, reliable operation, easy start and stop, low industrial investment cost and the like in design, and achieves the aims of improving the production efficiency, improving the safety and reducing the environmental pollution.
Drawings
FIG. 1 is a flow diagram of an isocyanate preparation process.
FIG. 2 is a graph of IR spectrum after neutralization reaction.
Description of reference numerals:
1. a photochemical reaction kettle; 2. a gas-liquid separator; 3. a reaction gas phase condenser; 4. a static mixer; 5. a continuous neutralization reactor; 6. a neutralization reaction heat exchanger; 7. a filtration/washing/drying all-in-one machine; 8. a rectifying tower; 9. recovering a neutralizing agent; 10. a condenser at the top of the rectifying tower; 11. a neutralizer collecting tank; 12 a solvent collection tank; 13. and (5) a product tank.
Detailed Description
The following describes the preparation of the isocyanates provided by the present invention in further detail with reference to the drawings and examples, but the present invention is not limited to the listed examples and is not limited thereby.
As shown in figure 1, the production device of the invention comprises a photochemical reaction kettle 1, a gas-liquid separator 2, a reaction gas phase condenser 3, a static mixer 4, a continuous neutralization reactor 5, a neutralization reaction heat exchanger 6, a filtering/washing/drying integrated machine 7, a rectifying tower 8, a neutralizer recovery 9, a rectifying tower top condenser 10, a neutralizer collecting tank 11, a solvent collecting tank 12 and a product tank 13, wherein the outlet of the photochemical reaction kettle 1 is connected with the inlet of the gas-liquid separator 2, the liquid outlet of the gas-liquid separator 2 is connected with the inlet of the reaction gas phase condenser 3, the liquid outlet of the reaction gas phase condenser 3 is connected with the inlet of the static mixer 4, the outlet of the static mixer 4 is connected with the inlet of the continuous neutralization reactor 5, the outlet of the continuous neutralization reactor 5 is connected with the neutralization reaction heat exchanger 6, the neutralization reaction heat exchanger 6 is further connected with the filtering/washing/drying integrated machine 7, a liquid outlet of the filtering/washing/drying integrated machine 7 is connected with a rectifying tower 8, and a condenser 10 at the top of the rectifying tower is respectively connected with a neutralizer collecting tank 11, a solvent collecting tank 12 and an isocyanate product tank 13. The solid outlet of the filtering/washing/drying integrated machine 7 is connected with a neutralizer collecting tank 11 through a neutralizer recovery processing device 9, the tail gas outlet of a condenser 10 at the top of the rectifying tower is connected with a tail gas processing device, the neutralizer collecting tank 11 is connected to the continuous neutralization reactor 5 through a pipeline, and the solvent collecting tank 12 is connected to the static mixer 4 and/or the photochemical reaction kettle 1 through a pipeline.
The equipment used in the invention is a general chemical reaction kettle, a condenser, a pump and the like. The diameter of a rotating disc of the used centrifugal separation equipment is 800mm, the diameter of a filter element is 10-25 mu m, the power of a motor is about 3 kilowatts, and the rotating speed of a high-speed centrifugal filter is controlled to be 300-500 rpm.
The condenser temperature is controlled by circulating water.
As shown in fig. 1 and 2: the isocyanate preparation process of the present invention comprises the steps of:
the phosgenation and neutralization reactions of the process are carried out in a continuous manner. A reaction kettle with a special mixer and a stirrer is used, the volume is 1000L, and nitrogen is introduced to remove oxygen and oxygen in the reaction kettle. 300kg of chlorobenzene was charged as a reaction solvent in advance, and stirring was started.
1. The system is filled with nitrogen for replacement, the dew point is lower than minus 38 ℃, and the moisture content is qualified.
2. After raw materials and phosgene are reacted in a reaction kettle 1, preheating to a preset temperature, generally 60-130 ℃, passing through a gas phase condenser (gas-liquid separator) 2, evaporating intermediates such as isocyanate, isocyanate acyl chloride and the like synthesized by reaction from a gas phase, and refluxing a solvent to the reaction kettle from the condenser.
3. Controlling the temperature of the reaction gas phase condenser 3 to be 15-30 ℃, and after the gas phase material is subjected to heat exchange by the reaction gas phase condenser 3, introducing phosgene and HCl non-condensable gas into a phosgene absorption system for recovery treatment. The mixture of isocyanate monomer and acid chloride, which is liquid at the condenser, and solvent are mixed in a static mixer 4 in a ratio of 1: 1-30 mass ratio, preferably 1: 2-15 mass ratio, then mixing, entering a continuous neutralization reactor 5, reacting with a neutralizing agent, continuously entering a neutralization reaction heat exchanger 6 for heat exchange, then continuously entering the neutralization reaction heat exchanger, and controlling the temperature of the materials to be cooled to about 30-50 ℃.
4. The slurry reaction liquid enters a general filtering/washing/drying integrated machine 7, the neutralizing agent hydrochloride is filtered and separated, the isocyanate-containing filtrate enters a rectification system for separation, and the neutralizing agent hydrochloride is recovered to a neutralizing agent tank 11 through a neutralizing agent recovery process 9 for recycling.
5. According to different material properties, isocyanate, a neutralizer and a solvent are extracted from the rectifying tower, the neutralizer is recycled in a neutralizer tank 11, the solvent is recycled in a solvent tank 12, and the isocyanate product is sent to a product tank 13.
Embodiments of the present invention are further illustrated by the following examples. The invention is not limited to the examples listed.
Example 1
By adopting the process steps, toluene is added into a normal pressure reaction kettle, nitrogen is replaced, then the mixture is stirred and heated, toluene is used as a solvent, methylamine hydrochloride and phosgene are introduced according to the molar ratio of 1:10, and 4kgf/cm2Reacting at the temperature of 110 ℃, heating a reaction product obtained after the reaction and comprising methylamino formyl chloride, phosgene and HCl to 75-80 ℃, enabling the reaction product to enter a gas-liquid separator, then passing through a reaction gas-phase condenser, controlling the temperature of the condenser by using chilled water at the temperature of 10-25 ℃, enabling uncondensed phosgene and hydrogen chloride to enter a phosgene absorption treatment process, enabling a condensation liquid comprising the amino formyl chloride and isocyanate to exchange heat to 15-30 ℃ in the reaction gas-phase condenser, and then mixing the condensation liquid with toluene in a static mixer, wherein the methylamino formyl chloride (MCC): toluene 1:8(m/m), triethylamine as neutralizer, methylcarbamoyl chloride (MCC): 1:1.2(mol/mol) of triethylamine, controlling the temperature of a heat exchanger to be lower than 30 ℃, carrying out continuous reaction, keeping the residence time for 5-15 seconds, enabling a reaction solution to enter a neutralization reaction heat exchanger for heat exchange to 20-30 ℃, then entering a filtering/washing/drying integrated machine, carrying out centrifugal filtration through a stainless steel filter screen with the thickness of 5 mu m, rotating at the speed of 500 r/min, washing a filter cake with toluene and carrying out vacuum drying treatment, recovering a neutralizing agent from a dried solid, treating hydrochloride through about 30% of sodium hydroxide, purifying and recovering triethylamine, feeding the triethylamine into a neutralizing agent collecting tank, and feeding the obtained filtrate into a rectifying tower for physical batch rectification; the rectification pressure is 101kpa (absolute pressure), the methyl isocyanate is extracted at 37-40 ℃ from the top of the tower, the triethylamine is extracted at 88-90 ℃ for recycling, the solvent toluene is extracted at 110-111 ℃, the purity of an analyzed product is 99.6%, the impurities at the bottom of the tower are methyl isocyanate tripolymer, and the total yield is 89.53%.
The IR spectrum after neutralization reaction is shown in FIG. 2.
Example 2
Adding o-dichlorobenzene into a normal pressure reaction kettle, replacing with nitrogen, stirring, heating, taking o-dichlorobenzene as a solvent, introducing ethylamine hydrochloride and phosgene in a molar ratio of 1:10, wherein the molar ratio is 5kgf/cm2Reacting at 110 deg.C and 150 deg.C to obtain a reaction productHeating a reaction product containing the ethyl carbamoyl chloride, the phosgene and the HCL to 100-105 ℃, then feeding the reaction product into a gas-liquid separator, controlling the temperature of a condenser by using chilled water at 15-30 ℃, and feeding the uncondensed phosgene and hydrogen chloride into a phosgene absorption treatment process after passing through a reaction gas-phase condenser, wherein the phosgene absorption treatment process comprises the steps of condensing the ethyl carbamoyl chloride and the ethyl isocyanate to a condensation liquid at 25-35 ℃, mixing the condensation liquid with o-dichlorobenzene in a static mixer, and mixing the ethyl carbamoyl chloride: o-dichlorobenzene ═ 1:8(m/m), triethylamine as the neutralizer, ethylcarbamoyl chloride: triethylamine is 1:1.2(mol/mol), the temperature of a heat exchanger is controlled to be lower than 40 ℃, continuous reaction is carried out, the reaction residence time is 3-10 seconds, the reaction liquid continuously enters a neutralization reaction heat exchanger for heat exchange to 30-45 ℃, then enters a filtering/washing/drying integrated machine, centrifugal filtration is carried out through a stainless steel filter screen with the diameter of 10 mu m, the rotating speed is 400 r/min, the filter cake is washed by o-dichlorobenzene and dried in vacuum, the dried solid is recycled by a neutralizer, about 30% of sodium hydroxide is used for treating hydrochloride, triethylamine is purified and recycled, the obtained filtrate is sent to a neutralizer collecting tank, and the obtained filtrate is sent to a rectifying tower for intermittent rectification; the rectification pressure is 101kpa (absolute pressure), ethyl isocyanate is extracted at the tower top at 58-60 ℃, solvent o-dichlorobenzene is extracted at 179-181 ℃, the purity of an analyzed product is 99.7%, impurities at the tower bottom are ethyl isocyanate tripolymer, and the total yield is 91.53%.
Example 3
And then, carrying out a plurality of times of synthesis experiments, detecting, and comparing with the conventional cracking reaction, wherein the comparison result is shown in table 1.
TABLE 1 comparison of the indexes of the two processes
| Detecting items | Unit of | Conventional reaction mixing | The process of the invention |
| Appearance of reaction solution | - | Dark brown liquid with large particles | Fine and stable white emulsion |
| Purity of the product | ％ | 94.2～95.5 | 97.1～99.5 |
| Product yield | ％ | 40.0～70.0 | 90.0～96.0 |
In the above examples, agilent 7890 was used to measure the purity and concentration of the reaction solution. IR was tested using FTIR.
Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.
Claims (28)
1. A method of preparing isocyanate monomers, the method comprising the steps of:
(A) adding amine hydrochloride and phosgene serving as raw materials into a reaction kettle, and carrying out a photochemical reaction in the presence of a solvent to obtain a reaction product of carbamoyl chloride and isocyanate gas;
(B) and (2) carrying out gas-liquid separation on the reaction product of the carbamyl chloride and the isocyanate gas, removing uncondensed phosgene and hydrogen chloride, and enabling the separated liquid to enter a static mixer and react with a solvent in a ratio of 1: 1-30 mass ratio, sending to a neutralization reactor, and carrying out neutralization reaction with a neutralizer to obtain a slurry reaction liquid, wherein the feeding molar ratio of the neutralizer to the carbamoyl chloride is 1-5: 1;
(C) and (C) carrying out solid-liquid separation on the reaction liquid obtained in the step (B), and sending the separated isocyanate-containing liquid into a rectification system for rectification separation to obtain an isocyanate product.
2. The method of claim 1, wherein the method further comprises one or more of the following steps:
(1) in the step (B), the uncondensed phosgene and hydrogen chloride are sent to a phosgene absorption process for absorption and recycling, and HCl is absorbed by water to generate by-product hydrochloric acid;
(2) in the step (C), the solid-liquid separation comprises the steps of feeding the reaction liquid obtained in the step (B) into a filter for filtration, then carrying out solid-liquid separation through centrifugation, and recycling the separated solid salt through a neutralizer recycling process;
(3) and (C) rectifying and separating to obtain excessive neutralizing agent and solvent, wherein the neutralizing agent and the solvent are recycled.
3. The method according to claim 1 or 2, wherein in the step (B), the separated liquid enters a static mixer and is remixed with the solvent in a mass ratio of 1: 2-15.
4. The method of claim 2, wherein the filter is a rotary filter.
5. The process according to claim 1 or 2, wherein the phosgene and hydrogen chloride are removed in step (B) by condensation at a temperature of 10 to 130 ℃; and/or the presence of a gas in the gas,
the reaction heat of the neutralization reaction is exchanged by a subsequent heat exchanger, and the temperature is controlled to be 10-70 ℃.
6. The method according to claim 5, wherein the phosgene and the hydrogen chloride are removed by condensation in the step (B), and the temperature of the treatment is 20-60 ℃; and/or the presence of a gas in the gas,
the reaction heat of the neutralization reaction is exchanged by a subsequent heat exchanger, and the temperature is controlled to be 20-50 ℃.
7. The process of claim 1 or 2, wherein in step (a), the molar ratio of phosgene to amine or amine hydrochloride is 1.1-5: 1; the amine is a mono-or bifunctional or higher chain aliphatic amine or cyclic aliphatic amine having a primary amine group.
8. The process of claim 7, wherein in step (A), the molar ratio of phosgene to amine or amine hydrochloride is 1.2-3: 1.
9. The method according to claim 7, wherein in step (A), the molar ratio of phosgene to amine or amine hydrochloride is 1.5-2: 1.
10. The method of claim 1 or 2, wherein the prepared isocyanate monomer is one or a mixture of two or more of toluene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, methylcyclohexyl diisocyanate, hydrogenated MDI, isophorone diisocyanate, p-phenylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, methyl isocyanate, ethyl isocyanate and butyl isocyanate in any proportion.
11. The process of claim 1 or 2, wherein the isocyanate monomers produced are methyl isocyanate and ethyl isocyanate.
12. The method according to claim 1 or 2, wherein the neutralizing agent is one or more selected from pyridine, imidazole, triethylamine.
13. The process according to claim 1 or 2, wherein the neutralizing agent is triethylamine and/or methylimidazole.
14. The process of claim 1 or 2, wherein the feed molar ratio of neutralizing agent to carbamoyl chloride is from 1.1 to 2: 1.
15. The method according to claim 1 or 2, wherein the ratio of the total feeding amount is controlled, and the concentration of the hydrochloride of the neutralizing agent contained in the slurry reaction liquid in the step (B) is between 1 and 30 wt%; the retention time of the neutralization reaction is 1-60 seconds.
16. A process as claimed in claim 15, wherein the total feed rate ratio is controlled such that the concentration of the hydrochloride of the neutralizing agent contained in the slurry reaction solution in the step (B) is 5 to 20% by weight; the residence time of the neutralization reaction is 3-15 seconds.
17. The method according to claim 1 or 2, wherein the solid-liquid separation in the step (C) is carried out by filtration, and the filtration diameter of the filtration equipment is 1 to 100 μm.
18. The method of claim 17, wherein the filtration device has a filtration diameter of between 10 and 25 μm.
19. The method of claim 17, wherein the filtration device is a centrifugal filter rotating at 50-2000 rpm.
20. The method of claim 19, wherein the rotation speed is 300 to 500 rpm.
21. The method according to claim 2, wherein the filtered isocyanate-containing filtrate is sent to a rectification system for rectification separation, the separation pressure is controlled to be 1-150 kPa absolute, and/or the top temperature of the rectification tower is 20-150 ℃ and the bottom operating temperature is 30-200 ℃.
22. The method according to claim 2, wherein the filtered isocyanate-containing filtrate is sent to a rectification system for rectification separation, the separation pressure is controlled to be 50-120 kPa absolute, and/or the top temperature of the rectification tower is 30-80 ℃ and the bottom operating temperature is 50-160 ℃.
23. An apparatus for preparing isocyanates, the apparatus comprising: a photochemical reaction kettle, a gas-liquid separator, a reaction gas-phase condenser, a mixer, a continuous neutralization reactor, a neutralization reaction heat exchanger, a filtering/washing/drying integrated machine and a rectifying tower,
the outlet of the photochemical reaction kettle is connected with the inlet of the gas-liquid separator, the gas outlet of the gas-liquid separator is connected with the inlet of the reaction gas phase condenser, the liquid outlet of the reaction gas phase condenser is connected with the inlet of the mixer, the outlet of the mixer is connected with the inlet of the continuous neutralization reactor, the outlet of the continuous neutralization reactor is connected with the neutralization reaction heat exchanger, the neutralization reaction heat exchanger is further connected with the inlet of the filtering/washing/drying integrated machine, and the liquid outlet of the filtering/washing/drying integrated machine is connected with the rectifying tower.
24. The apparatus of claim 23, wherein the mixer is a static mixer.
25. The apparatus of claim 23, wherein the solids outlet of the filtration/washing/drying integrated machine is connected to a neutralizer collection tank via a neutralizer recovery treatment device.
26. The apparatus according to claim 25, wherein the off-gas outlet of the rectification column overhead condenser is connected to an off-gas treatment apparatus, and/or,
the condenser at the top of the rectifying tower is respectively connected with a neutralizer collecting tank, a solvent collecting tank and an isocyanate product tank.
27. The apparatus of claim 25, wherein the neutralizer collection tank is connected to the continuous neutralization reactor by a conduit, and the solvent collection tank is connected to the static mixer and/or the photochemical reaction kettle by a conduit.
28. The apparatus of claim 26, wherein the neutralizer collection tank is connected to the continuous neutralization reactor by a conduit, and the solvent collection tank is connected to the static mixer and/or the photochemical reaction kettle by a conduit.
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| CN111450791B (en) * | 2020-05-08 | 2023-04-18 | 河南金鹏化工有限公司 | Continuous process and device for producing methomyl from methyl isocyanate |
| CN111454179B (en) * | 2020-05-08 | 2023-10-20 | 河南金鹏化工有限公司 | Device and continuous process for producing methyl isocyanate from dimethyl sulfate |
| KR102578617B1 (en) * | 2020-12-03 | 2023-09-13 | 에스케이씨 주식회사 | Xylylenediisocyanate composition and optical polymerizable composition including the same |
| US11753367B2 (en) | 2021-03-10 | 2023-09-12 | Mitsui Chemicals, Inc. | Xylylene diisocyanate composition, polymerizable composition for optical material, resin, molded article, optical element, and lens |
| CN113499747B (en) * | 2021-07-15 | 2023-04-18 | 扬州天启新材料股份有限公司 | Chlorination reaction device for cyanate synthesis |
| CN114432969B (en) * | 2022-04-07 | 2022-07-01 | 中国科学院过程工程研究所 | Device and method for preparing m-xylylene diisocyanate by non-phosgene method |
| CN115160255A (en) * | 2022-09-06 | 2022-10-11 | 科迈化工股份有限公司 | Method and system device for continuously producing 2-mercaptobenzothiazole |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4096165A (en) * | 1976-11-01 | 1978-06-20 | Allied Chemical Corporation | Method of manufacturing aromatic isocyanates |
| US4384999A (en) * | 1980-10-09 | 1983-05-24 | Spaziante Placido M | Preparation of alkyl isocyanates |
| EP0106138A1 (en) * | 1982-10-09 | 1984-04-25 | Hüls Aktiengesellschaft | Continuous process for the hot phosgenation of amines |
| CN101100447A (en) * | 2006-06-26 | 2008-01-09 | 拜尔材料科学股份公司 | Method for the continuous production of isocyanates |
| CN102498093A (en) * | 2009-07-09 | 2012-06-13 | 拜尔材料科学股份公司 | Method for producing isocyanates |
| CN102659631A (en) * | 2011-12-24 | 2012-09-12 | 德州绿邦化工有限公司 | One-step synthesis of ethyl isocyanate |
| CN103694190A (en) * | 2013-12-25 | 2014-04-02 | 沙隆达集团公司 | Production method and equipment of methyl isocyanate |
| CN104557613A (en) * | 2014-12-18 | 2015-04-29 | 海利贵溪化工农药有限公司 | Deslagging method for continuous production of methyl isocyanate |
-
2017
- 2017-11-08 CN CN201711091092.9A patent/CN109748822B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4096165A (en) * | 1976-11-01 | 1978-06-20 | Allied Chemical Corporation | Method of manufacturing aromatic isocyanates |
| US4384999A (en) * | 1980-10-09 | 1983-05-24 | Spaziante Placido M | Preparation of alkyl isocyanates |
| EP0106138A1 (en) * | 1982-10-09 | 1984-04-25 | Hüls Aktiengesellschaft | Continuous process for the hot phosgenation of amines |
| CN101100447A (en) * | 2006-06-26 | 2008-01-09 | 拜尔材料科学股份公司 | Method for the continuous production of isocyanates |
| CN102498093A (en) * | 2009-07-09 | 2012-06-13 | 拜尔材料科学股份公司 | Method for producing isocyanates |
| CN102659631A (en) * | 2011-12-24 | 2012-09-12 | 德州绿邦化工有限公司 | One-step synthesis of ethyl isocyanate |
| CN103694190A (en) * | 2013-12-25 | 2014-04-02 | 沙隆达集团公司 | Production method and equipment of methyl isocyanate |
| CN104557613A (en) * | 2014-12-18 | 2015-04-29 | 海利贵溪化工农药有限公司 | Deslagging method for continuous production of methyl isocyanate |
Non-Patent Citations (2)
| Title |
|---|
| Design, synthesis and evaluation of 1,2-benzisothiazol-3-one derivatives as potent caspase-3 inhibitors;Dazhi Liu et al;《Bioorganic & Medicinal Chemistry》;20131231;第21卷;2960-2967 * |
| 甲基异氰酸酯生产中副产物生成量研究;齐家炎等;《湖北化工》;20011231(第3期);42-43 * |
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