CN114031525B - Method for continuously preparing p-nitrotoluene ortho-sulfonic acid by using dynamic tubular reactor - Google Patents
Method for continuously preparing p-nitrotoluene ortho-sulfonic acid by using dynamic tubular reactor Download PDFInfo
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- C07C303/00—Preparation of esters or amides of sulfuric acids; Preparation of sulfonic acids or of their esters, halides, anhydrides or amides
- C07C303/02—Preparation of esters or amides of sulfuric acids; Preparation of sulfonic acids or of their esters, halides, anhydrides or amides of sulfonic acids or halides thereof
- C07C303/04—Preparation of esters or amides of sulfuric acids; Preparation of sulfonic acids or of their esters, halides, anhydrides or amides of sulfonic acids or halides thereof by substitution of hydrogen atoms by sulfo or halosulfonyl groups
- C07C303/06—Preparation of esters or amides of sulfuric acids; Preparation of sulfonic acids or of their esters, halides, anhydrides or amides of sulfonic acids or halides thereof by substitution of hydrogen atoms by sulfo or halosulfonyl groups by reaction with sulfuric acid or sulfur trioxide
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Abstract
The invention relates to a method for continuously preparing p-nitrotoluene ortho-sulfonic acid by utilizing a dynamic tubular reactor, which comprises the steps of introducing liquid p-nitrotoluene and sulfur trioxide gas into the dynamic tubular reactor according to the molar ratio of 1:1.02-1.20 for sulfonation reaction, removing free sulfur trioxide in vacuum from the sulfonation finished solution through a gas-liquid separator, adding deionized water and dilute acid mother liquor, performing high-temperature hydrolysis to obtain p-nitrotoluene ortho-sulfonic acid solution, and performing a series of process units of activated carbon adsorption impurity removal, thermal filtration and low-temperature crystallization on the p-nitrotoluene ortho-sulfonic acid solution to obtain the p-nitrotoluene ortho-sulfonic acid. The invention has the advantages of low production cost, simple process, high safety, extremely small amount of waste acid, 10-30kg (sulfuric acid concentration 50-55%) of waste acid per ton of product, continuous production, high production efficiency, product quality and yield, no need of solvent, and simple production process.
Description
Technical Field
The invention belongs to the technical field of preparation of para-nitrotoluene ortho-sulfonic acid, and particularly relates to a method for continuously preparing para-nitrotoluene ortho-sulfonic acid by using a dynamic tubular reactor.
Background
The p-nitrotoluene-o-sulfonic acid is an active substance and is an important intermediate for preparing stilbene direct dye, fluorescent brightening agent and multiple dyes, so that the research on the advanced process route for synthesizing the p-nitrotoluene-o-sulfonic acid has good practical value. The p-nitrotoluene sulfonation reaction is electrophilic substitution reaction, the methyl group is an electron donor group, and the activation effect on the ortho position is larger than that of the para position; the nitro group is an electron-withdrawing group, the passivation effect on the ortho position is larger than that of the meta position, and although four hydrogen which can be directly substituted are arranged on the benzene ring of the para-nitrotoluene, the sulfonation reaction is carried out on the hydrogen of the ortho position of the methyl substituted by the sulfonation group, the sulfonation reaction is extremely difficult to occur at other positions, and after one sulfonation, the disulfonation is basically avoided due to the steric hindrance effect.
The existing synthetic methods of the para-nitrotoluene ortho-sulfonic acid mainly comprise a high-temperature baking method, a sulfur trioxide/flux method, an excess fuming sulfuric acid method and a chlorosulfonic acid method. The high-temperature baking method has large labor capacity, and the volatilization and coking phenomena of the paranitrotoluene are serious; the excessive fuming sulfuric acid method has a large amount of dilute acid and high treatment difficulty; although the chlorosulfonic acid has good quality, the chlorosulfonic acid has high price, the byproduct of dilute hydrochloric acid is produced, and the production operation is complex. The sulfur trioxide/flux method is a new sulfonation technology proposed by recent researchers, and has the advantages of complex operation, certain safety risk, carbonization and oxidization of the solvent, influence on the product quality, high solvent loss and higher cost due to the fact that the method increases the technologies of solvent use, recovery and the like. In recent years, the sulfonation of paranitrotoluene by 50.0% or 65.0% fuming sulfuric acid can reduce the amount of sulfonated waste acid by 75.0%, but the sulfonation of PNT by 50.0% or 65.0% fuming sulfuric acid has the problem that the local concentration of sulfur trioxide is too high, and the product quality needs to be improved. In addition, the processes all adopt batch kettle type reaction, the sulfonation time is long, the oversulfonation phenomenon is serious, the byproducts are more, and the industrialization phenomenon has a plurality of difficulties.
The national institute of daily chemicals industry reports a continuous synthesis method (201810469086.0) of paranitrotoluene, which adopts low-concentration sulfur trioxide as a sulfonation reagent, and the low-concentration sulfur trioxide gas is introduced into a membrane reactor at a high speed, so that the paranitrotoluene is easy to sublimate, and the high-temperature gas flowing at a high speed can easily bring the paranitrotoluene easy to sublimate, thereby reducing the yield of products and increasing the difficulty of tail gas treatment. Meanwhile, sulfur trioxide needs to be diluted by dry air, and the preparation of the dry air needs to be subjected to deep condensation, drying, dehydration and other processes, so that the production cost is increased. In addition, in order to ensure good fluidity and uniform dispersion of materials in the membrane reactor, an organic solvent or an inorganic solvent is required, and processes such as solvent recovery, solvent dehydration and the like are required to be added in the follow-up process. It also mentions that one of the inorganic solvents is concentrated sulfuric acid, and sulfuric acid used as a solvent cannot be separated out and is finally converted into waste dilute sulfuric acid, and more waste acid is still generated although the amount of waste acid is reduced compared with fuming sulfuric acid.
At present, domestic enterprises still adopt the traditional kettle type process of sulfonating paranitrotoluene by 20% fuming sulfuric acid to produce paranitrotoluene ortho-sulfonic acid, the process is carried out in a reaction kettle, the reaction time is long, the production efficiency is low, the amount of byproduct waste acid is large, the byproduct of each ton of product is about 6-8 tons of dilute sulfuric acid with the concentration of 50.0%, the dilute sulfuric acid is dark in color, and the treatment difficulty is high. Sulfonation using oleum, whether it be economical or environmentally friendly, has not been adaptable to the needs of social development. Oleum sulfonation was listed in the limiting list in 2019. The development and application of new technologies of clean production, intrinsically safe continuous sulfonation and sulfur trioxide sulfonation belong to the encouragement class.
Disclosure of Invention
Aiming at the technical problems existing in the prior art, the invention provides a method for continuously preparing p-nitrotoluene ortho-sulfonic acid by using a dynamic tubular reactor, which has the advantages of low production cost, simple process, high safety, extremely small amount of waste acid, continuous production, high production efficiency, high product quality and yield, no need of using solvent and simplified production process.
The technical scheme for solving the technical problems is as follows:
a method for continuously preparing p-nitrotoluene ortho-sulfonic acid by using a dynamic tubular reactor, which comprises the following steps:
(1) Introducing mixed gas with the volume concentration of liquid paranitrotoluene and sulfur trioxide not lower than 50% into a dynamic tubular reactor with a stirring device for staged sulfonation, wherein the molar ratio of the paranitrotoluene to the sulfur trioxide is 1.0:1.02-1.20;
(2) Separating the sulfonated liquid by a gas-liquid separator, exhausting gas after cyclone, electric defogging, acid washing and alkali washing, discharging the liquid into a hydrolysis kettle from the bottom of the gas-liquid separator, and simultaneously starting a stirring device of the hydrolysis kettle, wherein the temperature is kept between 100 ℃ and 120 ℃;
(3) After the sulfonation completion liquid in the hydrolysis kettle reaches a preset liquid level, removing free sulfur trioxide in vacuum;
(4) Adding deionized water and dilute acid mother liquor which are 20-30% of the sulfonation finished liquor after free sulfur trioxide is removed from the sulfonation finished liquor in a hydrolysis kettle, hydrolyzing for 45-120min at 90-120 ℃, adding active carbon, preserving heat and stirring for 30-60min at 80-100 ℃, filtering while the active carbon is hot, feeding the filtrate into a crystallization kettle for low-temperature crystallization, and filtering to obtain p-nitrotoluene o-sulfonic acid crystals.
On the basis of the technical scheme, the invention can be improved as follows.
Further, in the step (3), the specific operation of removing the free sulfur trioxide in vacuum is as follows: and (3) starting a vacuum system connected to the hydrolysis kettle to remove free sulfur trioxide, wherein the vacuum degree of vacuum removal is-0.1 to-0.08 MPa, and the time is 20-60min.
Further, in the step (1), the length of the dynamic tubular reactor is 1-3m, the tubular reactor is arranged in a heat exchange area, the heat exchange area is divided into three sections, each section is provided with an independent temperature control area, an air inlet is distributed on the part of each section corresponding to the reactor, the first section is provided with a liquid paranitrotoluene feeding port except the air inlet, and the third section is provided with a sulfonation finishing liquid discharging port and an air outlet except the air inlet.
In the step (1), the mixed gas enters a dynamic tubular reactor in three parts, wherein the sulfur trioxide inflow amount of the first section is 40-50% of the total sulfur trioxide amount, the sulfur trioxide inflow amount of the second section is 30-40% of the total sulfur trioxide amount, and the sulfur trioxide inflow amount of the third section is 10-30% of the total sulfur trioxide amount.
Further, in the step (1), the dynamic tubular reactor is sulfonated by three sections of temperature control, wherein the first section of sulfonation reaction temperature is controlled to be 60-85 ℃, the second section of sulfonation reaction temperature is controlled to be 80-90 ℃, and the third section of sulfonation reaction temperature is controlled to be 90-110 ℃.
In the step (2), the liquid captured by cyclone and electric defogging is returned to the hydrolysis kettle for hydrolysis.
Further, in the step (2), the gas absorption liquid of the acid washing is 45-55% of diluted acid mother liquid, and the diluted acid mother liquid after gas absorption is used for hydrolysis of the sulfonation completion liquid.
Further, in the step (4), dilute acid mother liquor with the sulfuric acid concentration of 5-50% is added into the hydrolysis kettle.
Further, in the step (4), dilute acid mother liquor with the sulfuric acid concentration of 45-50% is added into the hydrolysis kettle.
Further, in the step (1), a conductivity meter monitoring process is installed at the outlet of the dynamic tubular reactor, the conductivity meter is linked with the stirring speed of the dynamic tubular reactor, and the complete sulfonation of the paranitrotoluene is ensured by adjusting the stirring speed.
The beneficial effects of the invention are as follows: the invention has the advantages of low production cost, simple process, high safety, extremely small amount of waste acid, 10-30kg (sulfuric acid concentration 50-55%) of waste acid per ton of product, continuous production, high production efficiency, product quality and yield, no need of solvent, and simple production process.
Drawings
FIG. 1 is a schematic structural view of a dynamic tubular reactor according to the present invention;
FIG. 2 is a process flow diagram of a method for continuously preparing para-nitrotoluene ortho-sulfonic acid using a dynamic tubular reactor according to the present invention.
Detailed Description
The principles and features of the present invention are described below with examples given for the purpose of illustration only and are not intended to limit the scope of the invention.
The percentages used in the present invention are mass percentages unless otherwise indicated.
The raw materials and the equipment adopted by the invention are conventional raw materials and equipment (conventional commercial products) in the technical field, and can be purchased in the market.
As shown in fig. 2, the method for continuously preparing p-nitrotoluene ortho-sulfonic acid by using a dynamic tubular reactor comprises the following steps:
(1) Introducing mixed gas with the volume concentration of liquid paranitrotoluene and sulfur trioxide not lower than 50% into a dynamic tubular reactor with a stirring device for staged sulfonation, wherein the molar ratio of the paranitrotoluene to the sulfur trioxide is 1.0:1.02-1.20;
(2) Separating the sulfonated liquid by a gas-liquid separator, exhausting gas after cyclone, electric defogging, acid washing and alkali washing, discharging the liquid into a hydrolysis kettle from the bottom of the gas-liquid separator, and simultaneously starting a stirring device of the hydrolysis kettle, wherein the temperature is kept between 100 ℃ and 120 ℃;
(3) After the sulfonation completion liquid in the hydrolysis kettle reaches a preset liquid level, removing free sulfur trioxide in vacuum to reduce the generation amount of dilute acid;
(4) Adding deionized water and dilute acid mother liquor which are 20-30% of the mass of the sulfonation finished solution after free sulfur trioxide is removed from the sulfonation finished solution in a hydrolysis kettle, hydrolyzing for 45-120min at 90-120 ℃ to obtain para-nitrotoluene ortho-sulfonic acid solution, adding activated carbon into the para-nitrotoluene ortho-sulfonic acid solution, preserving heat at 80-100 ℃, stirring for 30-60min, filtering while the solution is hot, feeding the filtrate into a crystallization kettle for low-temperature crystallization, and filtering to obtain para-nitrotoluene ortho-sulfonic acid crystals.
The addition amount of deionized water is controlled to ensure that the water balance and the dilute acid balance of the system can be kept for a long time, and the quality and the yield of the product can be controlled in a better range. In the invention, the deionized water has the following three main purposes: 1) Providing the crystallization water required by the para-nitrotoluene ortho-sulfonic acid product; 2) Providing water required by converting the sulfur trioxide which is not removed in the sulfonation finished liquid into sulfuric acid and water required by converting the sulfuric acid into about 50-55% of dilute acid; 3) The free water required for the para-nitrotoluene ortho-sulfonic acid product is provided. Through intensive researches and a large number of experiments, the inventor finds that if the water balance and the dilute acid balance of the system are kept for a long time, the concentration of the dilute acid mother solution is not higher than 55% and discharged, and the addition amount of deionized water is not less than 20% of the sulfonation finished solution. Occasionally, the adding amount of deionized water for one time is too small, and the result of a single test is not influenced, because the three parts of water can be obtained from the added dilute acid mother liquor, if the added water is too small for a long time, the acid concentration of the mother liquor can be continuously improved, and the acidity of the product crystallization mother liquor is more than 55%, so that the granularity of the product is reduced, the carried free water content is increased, and the product quality is reduced. The addition amount of deionized water should not be more than 30% of the sulfonation finished solution, because if the addition amount of deionized water is too large, the yield of the product is affected under the condition that the concentration of the added dilute acid mother solution is low. Therefore, in the present invention, it is very important to control the addition amount of deionized water.
Preferably, in step (1), sulfonation is carried out in stages in the range from 60 to 110 ℃. In order to provide the mixed gas with stable concentration of sulfur trioxide, the invention introduces dry air from the outlet of the sulfuric acid system industrial sulfuric acid absorption tower to adjust the concentration of sulfur trioxide in the mixed gas.
According to the invention, the dynamic tubular reactor is used as the sulfonation equipment, the high-concentration sulfur trioxide gas is used as the sulfonation reagent, the sulfur trioxide gas and the liquid paranitrotoluene pass through the dynamic tubular reactor in a molar ratio close to theory, so that the sulfonation reaction is completed instantaneously, the method is quick and efficient, the product quality is good, the yield is high, the problem of high yield of fuming sulfuric acid sulfonation waste sulfuric acid is effectively solved, meanwhile, a solvent is not required, and the production process is simple.
The invention also has a preferred development on the basis of the embodiments described above.
Preferably, in the step (3), the specific operation of removing the free sulfur trioxide in vacuum is as follows: and (3) starting a vacuum system connected to the hydrolysis kettle to remove free sulfur trioxide, wherein the vacuum degree of vacuum removal is-0.1 to-0.08 MPa, and the time is 20-60min.
Preferably, as shown in fig. 1, in step (1), the length of the dynamic tubular reactor is 1-3m, the tubular reactor is arranged in a heat exchange area, the heat exchange area is divided into three sections, each section is provided with an independent temperature control area, each section of heat exchange area is provided with an air inlet corresponding to a part of the reactor, the first section is provided with an air inlet, a liquid paranitrotoluene feed inlet is also provided, the third section is provided with an air inlet, and a sulfonation completion liquid drain outlet and an air outlet are also provided.
The dynamic tubular reactor adopts a three-section structural design, so that gas-liquid two-phase contact is more sufficient, the consumption of sulfur trioxide gas is reduced, and meanwhile, the sulfur trioxide gas and liquid paranitrotoluene are ensured to be fully sulfonated, thereby improving the product quality and yield and simultaneously effectively reducing the generation amount of dilute acid and the waste acid amount.
In the step (1), the mixed gas enters a dynamic tubular reactor in three parts, wherein the sulfur trioxide in the first section is introduced into 40-50% of the total sulfur trioxide, the sulfur trioxide in the second section is introduced into 30-40% of the total sulfur trioxide, and the sulfur trioxide in the third section is introduced into 10-30% of the total sulfur trioxide.
The mass ratio of the sulfur trioxide introduced into the first section, the second section and the third section is based on the research result of the inventor, so that the fluidity of the reaction solution in the tubular reactor can be improved, and the phenomenon of over sulfonation can be effectively prevented.
In the step (1), the inventor controls the temperature of the reaction system in stages according to the characteristics of the raw materials and the sulfonated materials through the results of full research and experiments. Specifically, the first stage sulfonation reaction temperature of the dynamic tubular reactor is controlled to be 60-85 ℃, the second stage sulfonation reaction temperature is controlled to be 80-90 ℃, and the third stage sulfonation reaction temperature is controlled to be 90-110 ℃.
Preferably, in the step (2), the liquid captured by cyclone and electric defogging flows back to the hydrolysis kettle for hydrolysis recovery, so that the yield of the paranitrotoluene ortho-sulfonic acid is further improved, the waste of resources is reduced, and in addition, the production cost can be reduced without additionally adding treatment equipment.
Preferably, in the step (2), the gas absorption liquid used for acid washing is 45-55% of diluted acid mother liquid, and the diluted acid mother liquid after gas absorption is used for hydrolysis of the sulfonation completion liquid.
In the step (4), dilute acid mother liquor with the sulfuric acid concentration of 5-50% is added into the hydrolysis kettle, preferably, dilute acid mother liquor with the sulfuric acid concentration of 45-50% is added into the hydrolysis kettle, and the addition amount of the dilute acid mother liquor and the sulfuric acid concentration are in inverse relation. Thereby ensuring that the water balance and the dilute acid balance of the system can be kept for a long time and further improving the yield of the product.
According to the invention, the dynamic tubular reactor is adopted as the sulfonation equipment to replace the kettle reactor, and on the premise of no solvent, the gas phase and the liquid phase can be fully contacted by stirring, and the sulfonation completion liquid is pushed to flow forwards, so that the requirement of a high-viscosity reaction system is met.
In order to ensure continuous and stable operation of sulfonation reaction, sulfonation completion liquid in the dynamic tubular reactor is discharged into the gas-liquid separator from the liquid outlet, non-condensable gas is discharged into the cyclone separator from the gas outlet, the bottom outlet of the gas-liquid separator is connected with a plurality of hydrolysis kettles, after continuous sulfonation for a period of time, the sulfonation completion liquid in the hydrolysis kettles is collected to a preset liquid level, and then the sulfonation completion liquid is cut into other empty hydrolysis kettles.
Preferably, a conductivity meter monitoring process is arranged at the outlet of the dynamic tubular reactor, the conductivity meter is linked with the stirring speed of the dynamic tubular reactor, when the fact that the paranitrotoluene is not completely sulfonated is found, the stirring speed is timely adjusted, the reaction time is prolonged, otherwise, the stirring speed is increased, the reaction time is shortened, and therefore the complete sulfonation of the paranitrotoluene is guaranteed by adjusting the stirring speed.
The following are specific embodiments of the invention.
Example 1
Liquid paranitrotoluene conveyed by a tank truck is conveyed to a storage tank area through a pump, then conveyed to an intermediate tank of a production area through a pipeline, and pumped into a high-level metering tank. The temperature of the paranitrotoluene is controlled to be 60-70 ℃ so as to prevent the paranitrotoluene from solidifying.
And (3) starting a stirring device of the dynamic tubular reactor, and starting heat exchange medium inlet valves b1, b2 and b3 and heat exchange medium outlet valves c1, c2 and c 3. Then simultaneously starting a paranitrotoluene feed pump and a mixed gas fan, continuously pumping liquid paranitrotoluene into the dynamic tubular reactor from the feed port a1 at a constant speed of 25.0g/s, and introducing mixed gas with the volume concentration of 92% of sulfur trioxide into the dynamic tubular reactor from the gas inlets g1, g2 and g3 of the tubular reactor at the speeds of 1.82L/s, 1.82L/s and 0.91L/s respectively. The molar ratio of paranitrotoluene to sulfur trioxide entering the dynamic tubular reactor at this time was 1:1.02, the mass ratio of sulfur trioxide introduced into the first section, the second section and the third section is 4:4:2. the temperature of the first stage sulfonation reaction is controlled to be in the range of 70-75 ℃, the temperature of the second stage sulfonation reaction is controlled to be in the range of 80-90 ℃ and the temperature of the third stage sulfonation reaction is controlled to be in the range of 100-105 ℃ by adjusting the inlet valves of the heat exchange media b1, b2 and b3 and the outlet valves of the heat exchange media c1, c2 and c 3.
The non-condensable gas is discharged into a cyclone separator from a g4 gas outlet of the dynamic tubular reactor, and is discharged after cyclone, electric defogging, acid washing and alkali washing; the sulfonation completion liquid is discharged from a liquid outlet of the dynamic reactor a2 into a gas-liquid separator, flows into a hydrolysis kettle with a stirring device through the bottom of the gas-liquid separator, starts the stirring device of the hydrolysis kettle and keeps the temperature at 100-105 ℃. Continuously sulfonating for 120min, collecting 285kg of sulfonation completion liquid in the hydrolysis kettle, starting a vacuum system connected to the hydrolysis kettle to remove free sulfur trioxide, and simultaneously cutting the sulfonation completion liquid into another empty hydrolysis kettle.
After the sulfonation finished solution is subjected to vacuum removal of free sulfur trioxide, 57kg of deionized water and 1200kg of dilute acid mother liquor with the sulfuric acid concentration of 15% are added; hydrolyzing at 105-110deg.C for 60min, adding active carbon, stirring at 80-90deg.C for 60min, filtering while hot, crystallizing at low temperature in a crystallization kettle, and filtering to obtain p-nitrotoluene o-sulfonic acid product 337kg containing free water 3.4% and two crystal water; the yield was 98.1% and the mother liquor was pumped into a storage tank for hydrolysis of the next batch of sulphonated liquor.
In order to ensure continuous and normal operation of the system, the free sulfur trioxide in the sulfonation finished liquid needs to be discharged from the system in time in the form of dilute sulfuric acid, and 15kg of waste acid mother liquor with the sulfuric acid concentration of 50% is discharged every 1 ton of paranitrotoluene ortho-sulfonic acid product produced in the embodiment.
Example 2
Liquid paranitrotoluene conveyed by a tank truck is conveyed to a storage tank area through a pump, then conveyed to an intermediate tank of a production area through a pipeline, and pumped into a high-level metering tank. The temperature of the paranitrotoluene is controlled to be 60-70 ℃ so as to prevent the paranitrotoluene from solidifying.
And (3) starting a stirring device of the dynamic tubular reactor, and starting heat exchange medium inlet valves b1, b2 and b3 and heat exchange medium outlet valves c1, c2 and c 3. Then simultaneously starting a paranitrotoluene feed pump and a mixed gas fan, continuously pumping liquid paranitrotoluene into the dynamic tubular reactor from the feed port a1 at a constant speed of 25.0g/s, and introducing mixed gas with the volume concentration of sulfur trioxide of 80% into the dynamic tubular reactor from the gas inlets g1, g2 and g3 of the tubular reactor at the speeds of 2.94L/s, 1.76L/s and 1.18L/s respectively. The molar ratio of paranitrotoluene to sulfur trioxide entering the dynamic tubular reactor at this time was 1: 1.15, the mass ratio of sulfur trioxide introduced into the first section, the second section and the third section is 5:3:2. the temperature of the first stage sulfonation reaction is controlled to be 80-85 ℃ by adjusting the inlet valves of the heat exchange media b1, b2 and b3 and the outlet valves of the heat exchange media c1, c2 and c3, the temperature of the second stage sulfonation reaction is controlled to be 85-90 ℃, and the temperature of the third stage sulfonation reaction is controlled to be 105-110 ℃.
The non-condensable gas is discharged into a cyclone separator from a g4 gas outlet of the dynamic tubular reactor, is discharged after cyclone, electric defogging, acid washing and alkali washing, and is discharged, and liquid captured by the cyclone and the electric defogging is returned to a hydrolysis kettle for hydrolysis; the sulfonation completion liquid is discharged from a liquid outlet of the dynamic reactor a2 into a gas-liquid separator, flows into a hydrolysis kettle with a stirring device through the bottom of the gas-liquid separator, starts the stirring device of the hydrolysis kettle and keeps the temperature at 110-120 ℃. Continuously sulfonating for 120min, collecting 290kg of sulfonation completion liquid in the hydrolysis kettle, starting a vacuum system connected to the hydrolysis kettle to remove free sulfur trioxide, wherein the vacuum degree of vacuum removal is-0.09 MPa, the time is 40min, and simultaneously cutting the sulfonation completion liquid into another empty hydrolysis kettle.
After the sulfonation finished solution is subjected to vacuum removal of free sulfur trioxide, 72.5kg of deionized water and 870kg of dilute acid mother solution with the sulfuric acid concentration of 45% are added; hydrolyzing at 100-105deg.C for 80min, adding activated carbon, stirring at 80-90deg.C for 40min, filtering while hot, crystallizing at low temperature in a crystallization kettle, and filtering to obtain 340kg of p-nitrotoluene o-sulfonic acid product containing 3.5% free water and two crystal water; the yield was 98.8% and the mother liquor was pumped into a storage tank for hydrolysis of the next batch of sulphonated liquor.
In order to ensure continuous and normal operation of the system, the free sulfur trioxide in the sulfonation finished liquid needs to be timely discharged from the system in the form of dilute sulfuric acid, and 23kg of waste acid mother liquor with the sulfuric acid concentration of 52% is discharged per 1 ton of p-nitrotoluene o-sulfonic acid product produced in the embodiment.
Example 3
Liquid paranitrotoluene conveyed by a tank truck is conveyed to a storage tank area through a pump, then conveyed to an intermediate tank of a production area through a pipeline, and pumped into a high-level metering tank. The temperature of the paranitrotoluene is controlled to be 60-70 ℃ so as to prevent the paranitrotoluene from solidifying.
And (3) starting a stirring device of the dynamic tubular reactor, and starting heat exchange medium inlet valves b1, b2 and b3 and heat exchange medium outlet valves c1, c2 and c 3. Then simultaneously starting a paranitrotoluene feed pump and a mixed gas fan, continuously pumping liquid paranitrotoluene into the dynamic tubular reactor from the feed port a1 at a constant speed of 25.0g/s, and introducing mixed gas with the volume concentration of sulfur trioxide of 70% into the dynamic tubular reactor from the gas inlets g1, g2 and g3 of the tubular reactor at the speeds of 3.5L/s, 2.8L/s and 0.7L/s respectively. The molar ratio of paranitrotoluene to sulfur trioxide entering the dynamic tubular reactor at this time was 1:1.2, the mass ratio of sulfur trioxide introduced into the first section, the second section and the third section is 5:4:1. the temperature of the first stage sulfonation reaction is controlled to be 75-80 ℃ by adjusting the inlet valves of the heat exchange media b1, b2 and b3 and the outlet valves of the heat exchange media c1, c2 and c3, the temperature of the second stage sulfonation reaction is controlled to be 80-85 ℃, and the temperature of the third stage sulfonation reaction is controlled to be 90-95 ℃.
The non-condensable gas is discharged into a cyclone separator from a g4 gas outlet of the dynamic tubular reactor, is discharged after cyclone, electric defogging, acid washing and alkali washing, and is discharged, and liquid captured by the cyclone and the electric defogging is returned to a hydrolysis kettle for hydrolysis; the sulfonation completion liquid is discharged from a liquid outlet of the dynamic reactor a2 into a gas-liquid separator, flows into a hydrolysis kettle with a stirring device through the bottom of the gas-liquid separator, starts the stirring device of the hydrolysis kettle and keeps the temperature at 110-115 ℃. Continuously sulfonating for 120min, collecting 288kg of sulfonation completion liquid in the hydrolysis kettle, starting a vacuum system connected to the hydrolysis kettle to remove free sulfur trioxide, wherein the vacuum degree of vacuum removal is-0.1 MPa, the time is 20min, and simultaneously cutting the sulfonation completion liquid into another empty hydrolysis kettle.
After the sulfonation finished solution is subjected to vacuum removal of free sulfur trioxide, 86.4kg of deionized water and 576kg of dilute acid mother solution with the sulfuric acid concentration of 50% are added; hydrolyzing at 90-95deg.C for 120min, adding active carbon, stirring at 80-90deg.C for 50min, filtering while hot, crystallizing at low temperature in a crystallization kettle, and filtering to obtain 339kg of p-nitrotoluene o-sulfonic acid product containing 3.6% free water and two crystal water; the yield was 98.4% and the mother liquor was pumped into a storage tank for hydrolysis of the next batch of sulphonated liquor.
In order to ensure continuous and normal operation of the system, the free sulfur trioxide in the sulfonation finished liquid needs to be discharged from the system in time in the form of dilute sulfuric acid, and 30kg of waste acid mother liquor with the sulfuric acid concentration of 53% is discharged every 1 ton of paranitrotoluene ortho-sulfonic acid product produced in the embodiment.
Example 4
Liquid paranitrotoluene conveyed by a tank truck is conveyed to a storage tank area through a pump, then conveyed to an intermediate tank of a production area through a pipeline, and pumped into a high-level metering tank. The temperature of the paranitrotoluene is controlled to be 60-70 ℃ so as to prevent the paranitrotoluene from solidifying.
And (3) starting a stirring device of the dynamic tubular reactor, and starting heat exchange medium inlet valves b1, b2 and b3 and heat exchange medium outlet valves c1, c2 and c 3. Then simultaneously starting a paranitrotoluene feed pump and a mixed gas fan, continuously pumping liquid paranitrotoluene into the dynamic tubular reactor from the a1 feed port at a constant speed of 12.5g/s, and introducing mixed gas with the volume concentration of 50% of sulfur trioxide into the dynamic tubular reactor from the g1, g2 and g3 gas inlets of the tubular reactor at the speeds of 1.8L/s, 1.8L/s and 0.9L/s respectively. The molar ratio of paranitrotoluene to sulfur trioxide entering the dynamic tubular reactor at this time was 1: 1.1, the mass ratio of sulfur trioxide introduced into the first section, the second section and the third section is 4:4:2. the temperature of the first stage sulfonation reaction is controlled to be in the range of 60-65 ℃ respectively, the temperature of the second stage sulfonation reaction is controlled to be in the range of 80-85 ℃ respectively, and the temperature of the third stage sulfonation reaction is controlled to be in the range of 95-100 ℃ respectively by adjusting the inlet valves of the heat exchange media b1, b2 and b3 and the outlet valves of the heat exchange media c1, c2 and c 3.
The non-condensable gas is discharged into a cyclone separator from a g4 gas outlet of the dynamic tubular reactor, and is discharged after cyclone, electric defogging, acid washing and alkali washing; the sulfonation completion liquid is discharged from a liquid outlet of the dynamic reactor a2 into a gas-liquid separator, flows into a hydrolysis kettle with a stirring device through the bottom of the gas-liquid separator, starts the stirring device of the hydrolysis kettle and keeps the temperature at 115-120 ℃. Continuously sulfonating for 120min, collecting 144kg of sulfonation completion liquid in the hydrolysis kettle, starting a vacuum system connected to the hydrolysis kettle to remove free sulfur trioxide, and simultaneously cutting the sulfonation completion liquid into another empty hydrolysis kettle.
After the sulfonation finished solution is subjected to vacuum removal of free sulfur trioxide, 36kg of deionized water and 425kg of dilute acid mother solution with the sulfuric acid concentration of 30% are added; hydrolyzing at 110-120deg.C for 45min, adding active carbon, stirring at 90-100deg.C for 45min, filtering, crystallizing at low temperature, filtering to obtain 169kg of p-nitrotoluene o-sulfonic acid product containing 3.5% free water and two crystal water; the yield was 98.2% and the mother liquor was pumped into a storage tank for hydrolysis of the next batch of sulphonated liquor.
In order to ensure continuous and normal operation of the system, the free sulfur trioxide in the sulfonation finished liquid needs to be timely discharged from the system in the form of dilute sulfuric acid, and 20kg of waste acid mother liquor with the sulfuric acid concentration of 51% is discharged every 1 ton of paranitrotoluene ortho-sulfonic acid product produced in the embodiment.
Example 5
Liquid paranitrotoluene conveyed by a tank truck is conveyed to a storage tank area through a pump, then conveyed to an intermediate tank of a production area through a pipeline, and pumped into a high-level metering tank. The temperature of the paranitrotoluene is controlled to be 60-70 ℃ so as to prevent the paranitrotoluene from solidifying.
And (3) starting a stirring device of the dynamic tubular reactor, and starting heat exchange medium inlet valves b1, b2 and b3 and heat exchange medium outlet valves c1, c2 and c 3. Then simultaneously starting a paranitrotoluene feed pump and a mixed gas fan, continuously pumping liquid paranitrotoluene into the dynamic tubular reactor from the feed port a1 at a constant speed of 25.0g/s, and introducing mixed gas with the volume concentration of sulfur trioxide of 60% into the dynamic tubular reactor from the gas inlets g1, g2 and g3 of the tubular reactor at the speeds of 2.88L/s, 2.16L/s and 2.16L/s respectively. The molar ratio of paranitrotoluene to sulfur trioxide entering the dynamic tubular reactor at this time was 1: 1.06, the mass ratio of the sulfur trioxide introduced into the first section, the second section and the third section is 4:3:3. the temperature of the first stage sulfonation reaction is controlled to be 65-70 ℃, the temperature of the second stage sulfonation reaction is controlled to be 85-90 ℃ and the temperature of the third stage sulfonation reaction is controlled to be 105-110 ℃ by adjusting the inlet valves of the heat exchange media b1, b2 and b3 and the outlet valves of the heat exchange media c1, c2 and c 3.
The non-condensable gas is discharged into a cyclone separator from a g4 gas outlet of the dynamic tubular reactor, is discharged after cyclone, electric defogging, acid washing and alkali washing, and is discharged, and liquid captured by the cyclone and the electric defogging is returned to a hydrolysis kettle for hydrolysis; the sulfonation completion liquid is discharged from a liquid outlet of the dynamic reactor a2 into a gas-liquid separator, flows into a hydrolysis kettle with a stirring device through the bottom of the gas-liquid separator, starts the stirring device of the hydrolysis kettle and keeps the temperature at 105-110 ℃. And continuously sulfonating for 75min, collecting 180kg of sulfonation completion liquid in the hydrolysis kettle, starting a vacuum system connected to the hydrolysis kettle to remove free sulfur trioxide, wherein the vacuum degree of vacuum removal is-0.08 MPa, the time is 60min, and simultaneously cutting the sulfonation completion liquid into another empty hydrolysis kettle.
After the sulfonation finished solution is subjected to vacuum removal of free sulfur trioxide, 45kg of deionized water and 900kg of dilute acid mother solution with 5% sulfuric acid concentration are added; hydrolyzing at 95-100deg.C for 100min, adding active carbon, stirring at 90-100deg.C for 30min, filtering, crystallizing at low temperature, filtering to obtain 211kg p-nitrotoluene o-sulfonic acid product containing 3.3% free water and two crystal water; the yield was 98.2% and the mother liquor was pumped into a storage tank for hydrolysis of the next batch of sulphonated liquor.
In order to ensure continuous and normal operation of the system, the free sulfur trioxide in the sulfonation finished liquid needs to be discharged from the system in time in the form of dilute sulfuric acid, and 20kg of waste acid mother liquor with the sulfuric acid concentration of 50% is discharged every 1 ton of paranitrotoluene ortho-sulfonic acid product produced in the embodiment.
Example 6
Liquid paranitrotoluene conveyed by a tank truck is conveyed to a storage tank area through a pump, then conveyed to an intermediate tank of a production area through a pipeline, and pumped into a high-level metering tank. The temperature of the paranitrotoluene is controlled to be 60-70 ℃ so as to prevent the paranitrotoluene from solidifying.
And (3) starting a stirring device of the dynamic tubular reactor, and starting heat exchange medium inlet valves b1, b2 and b3 and heat exchange medium outlet valves c1, c2 and c 3. Then simultaneously starting a paranitrotoluene feed pump and a mixed gas fan, continuously pumping liquid paranitrotoluene into the dynamic tubular reactor from the feed port a1 at a constant speed of 25.0g/s, and introducing mixed gas with the volume concentration of 80% of sulfur trioxide into the dynamic tubular reactor from the gas inlets g1, g2 and g3 of the tubular reactor at the speeds of 1.76L/s, 2.94L/s and 1.18L/s respectively. The molar ratio of paranitrotoluene to sulfur trioxide entering the dynamic tubular reactor at this time was 1: 1.15, the mass ratio of sulfur trioxide introduced into the first section, the second section and the third section is 3:5:2. the temperature of the first stage sulfonation reaction is controlled to be in the range of 90-95 ℃ respectively, the temperature of the second stage sulfonation reaction is controlled to be in the range of 95-100 ℃ respectively, and the temperature of the third stage sulfonation reaction is controlled to be in the range of 100-105 ℃ respectively by adjusting the inlet valves of the heat exchange media b1, b2 and b3 and the outlet valves of the heat exchange media c1, c2 and c 3.
The non-condensable gas is discharged into a cyclone separator from a g4 gas outlet of the dynamic tubular reactor, and is discharged after cyclone, electric defogging, acid washing and alkali washing; the sulfonation completion liquid is discharged from a liquid outlet of the dynamic reactor a2 into a gas-liquid separator, flows into a hydrolysis kettle with a stirring device through the bottom of the gas-liquid separator, starts the stirring device of the hydrolysis kettle and keeps the temperature at 110-120 ℃. Continuously sulfonating for 120min, collecting 286kg of sulfonation completion liquid in the hydrolysis kettle, starting a vacuum system connected to the hydrolysis kettle to remove free sulfur trioxide, and simultaneously cutting the sulfonation completion liquid into another empty hydrolysis kettle.
After the sulfonation finished solution is subjected to vacuum removal of free sulfur trioxide, 71.5kg of deionized water and 858kg of dilute acid mother solution with the sulfuric acid concentration of 45% are added; hydrolyzing at 100-105deg.C for 80min, adding activated carbon, stirring at 80-90deg.C for 40min, filtering while hot, crystallizing at low temperature in a crystallization kettle, and filtering to obtain 336kg of p-nitrotoluene o-sulfonic acid product containing 3.7% free water and two crystal water; the yield was 97.5% and the mother liquor was pumped into a storage tank for hydrolysis of the next batch of sulphonated liquor.
In order to ensure continuous and normal operation of the system, the free sulfur trioxide in the sulfonation finished liquid needs to be timely discharged from the system in the form of dilute sulfuric acid, and 25kg of waste acid mother liquor with the sulfuric acid concentration of 55% is discharged every 1 ton of paranitrotoluene ortho-sulfonic acid product produced in the embodiment.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the invention are intended to be included within the scope of the invention.
Claims (6)
1. A method for continuously preparing p-nitrotoluene ortho-sulfonic acid by using a dynamic tubular reactor, which is characterized by comprising the following steps:
(1) Introducing mixed gas with the volume concentration of liquid paranitrotoluene and sulfur trioxide not lower than 50% into a dynamic tubular reactor with a stirring device for staged sulfonation, wherein the molar ratio of the paranitrotoluene to the sulfur trioxide is 1.0:1.02-1.20;
(2) Separating the sulfonated liquid by a gas-liquid separator, exhausting gas after cyclone, electric defogging, acid washing and alkali washing, discharging the liquid into a hydrolysis kettle from the bottom of the gas-liquid separator, and simultaneously starting a stirring device of the hydrolysis kettle, wherein the temperature is kept between 100 ℃ and 120 ℃;
(3) After the sulfonation completion liquid in the hydrolysis kettle reaches a preset liquid level, removing free sulfur trioxide in vacuum;
(4) Adding deionized water and dilute acid mother liquor with the sulfuric acid concentration of 5-50% into a hydrolysis kettle after free sulfur trioxide is removed from the sulfonation completion liquid, wherein the deionized water accounts for 20-30% of the sulfonation completion liquid, the dilute acid mother liquor accounts for 2-5 times of the sulfonation completion liquid, hydrolyzing for 45-120min at 90-120 ℃, adding active carbon, preserving heat and stirring for 30-60min at 80-100 ℃, filtering while the solution is hot, feeding the filtrate into a crystallization kettle for low-temperature crystallization, and filtering to obtain p-nitrotoluene ortho-sulfonic acid crystals;
in the step (1), the length of the dynamic tubular reactor is 1-3m, the tubular reactor is arranged in a heat exchange area, the heat exchange area is divided into three sections, each section is provided with an independent temperature control area, the part of each section of heat exchange area corresponding to the reactor is provided with an air inlet, the first section is provided with a liquid paranitrotoluene feeding port except the air inlet, and the third section is provided with a sulfonation finishing liquid discharging port and an air outlet except the air inlet;
in the step (1), the mixed gas enters a dynamic tubular reactor in three parts, wherein the sulfur trioxide in the first section is introduced into 40-50% of the total sulfur trioxide, the sulfur trioxide in the second section is introduced into 30-40% of the total sulfur trioxide, and the sulfur trioxide in the third section is introduced into 10-30% of the total sulfur trioxide;
in the step (1), the dynamic tubular reactor is sulfonated by three sections of temperature control, wherein the temperature of the first section of sulfonation reaction is controlled to be 60-85 ℃, the temperature of the second section of sulfonation reaction is controlled to be 80-90 ℃, and the temperature of the third section of sulfonation reaction is controlled to be 90-110 ℃.
2. The method according to claim 1, wherein in step (3), the specific operation of removing free sulfur trioxide in vacuo is as follows: and (3) starting a vacuum system connected to the hydrolysis kettle to remove free sulfur trioxide, wherein the vacuum degree of vacuum removal is-0.1 to-0.08 MPa, and the time is 20-60min.
3. The method of claim 1, wherein in step (2), the liquid captured by cyclone and electric defogging is returned to the hydrolysis kettle for hydrolysis.
4. The method according to claim 1, wherein in the step (2), the gas absorption liquid for acid washing is 45-55% of a diluted acid mother liquid, and the diluted acid mother liquid after gas absorption is used for hydrolysis of a sulfonation completion liquid.
5. The method according to claim 1, wherein in the step (4), a dilute acid mother solution having a sulfuric acid concentration of 45 to 50% is added to the hydrolysis tank.
6. The method according to claim 1, wherein in the step (1), a conductivity meter is installed at the outlet of the dynamic tubular reactor to monitor the process, the conductivity meter is interlocked with the stirring speed of the dynamic tubular reactor, and the complete sulfonation of the paranitrotoluene is ensured by adjusting the stirring speed.
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| US3840591A (en) * | 1973-04-25 | 1974-10-08 | Ciba Geigy Corp | Process for the production of p-nitrotoluene-2-sulfonic acid |
| DE2916912A1 (en) * | 1979-04-26 | 1980-11-06 | Bayer Ag | METHOD FOR PRODUCING 4-NITROTOLUOL-2-SULPHONIC ACID |
| CH647502A5 (en) * | 1981-03-02 | 1985-01-31 | Sandoz Ag | Sulphonation of ortho-nitrochlorobenzene, para-nitrochlorobenzene and ortho-nitrotoluene |
| JPH0413655A (en) * | 1990-05-08 | 1992-01-17 | Nissan Chem Ind Ltd | Production of 2-nitrotoluene-4-sulfonic acid |
| CN101691345A (en) * | 2009-10-15 | 2010-04-07 | 武汉青江化工股份有限公司 | Process for sulfonation by jetting and absorbing pure sulfur trioxide |
| CN101692063B (en) * | 2009-10-15 | 2013-02-27 | 武汉青江化工股份有限公司 | Method for detecting process and end point of sulfur trioxide sulfonation |
| CN108586296B (en) * | 2018-05-16 | 2021-08-10 | 中国日用化学研究院有限公司 | Continuous synthesis method of p-nitrotoluene-o-sulfonic acid |
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