CN114436883B - Method for recovering N, N-dimethylacetamide from multi-element solution system - Google Patents
Method for recovering N, N-dimethylacetamide from multi-element solution system Download PDFInfo
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- CN114436883B CN114436883B CN202011119484.3A CN202011119484A CN114436883B CN 114436883 B CN114436883 B CN 114436883B CN 202011119484 A CN202011119484 A CN 202011119484A CN 114436883 B CN114436883 B CN 114436883B
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- dimethylacetamide
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- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 title claims abstract description 87
- 238000000034 method Methods 0.000 title claims abstract description 56
- 229910010272 inorganic material Inorganic materials 0.000 claims abstract description 60
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- 229910000272 alkali metal oxide Inorganic materials 0.000 claims abstract description 14
- 239000011344 liquid material Substances 0.000 claims abstract description 8
- 239000011343 solid material Substances 0.000 claims abstract description 8
- 238000000926 separation method Methods 0.000 claims abstract description 7
- 238000002156 mixing Methods 0.000 claims abstract description 5
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- FJKROLUGYXJWQN-UHFFFAOYSA-N papa-hydroxy-benzoic acid Natural products OC(=O)C1=CC=C(O)C=C1 FJKROLUGYXJWQN-UHFFFAOYSA-N 0.000 claims description 57
- 229960004889 salicylic acid Drugs 0.000 claims description 57
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical group [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 54
- -1 compound inorganic compound Chemical class 0.000 claims description 46
- 238000010992 reflux Methods 0.000 claims description 38
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 32
- KKCBUQHMOMHUOY-UHFFFAOYSA-N sodium oxide Chemical group [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 claims description 15
- 229910001948 sodium oxide Inorganic materials 0.000 claims description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 14
- 239000002351 wastewater Substances 0.000 claims description 12
- 239000002253 acid Substances 0.000 claims description 11
- 238000000605 extraction Methods 0.000 claims description 8
- 150000007522 mineralic acids Chemical class 0.000 claims description 5
- 238000004821 distillation Methods 0.000 claims description 3
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 3
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- 230000020477 pH reduction Effects 0.000 claims description 2
- 238000011084 recovery Methods 0.000 abstract description 47
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- 239000003513 alkali Substances 0.000 description 13
- 238000001556 precipitation Methods 0.000 description 13
- 239000012071 phase Substances 0.000 description 12
- ABBQHOQBGMUPJH-UHFFFAOYSA-M Sodium salicylate Chemical compound [Na+].OC1=CC=CC=C1C([O-])=O ABBQHOQBGMUPJH-UHFFFAOYSA-M 0.000 description 7
- 150000007524 organic acids Chemical class 0.000 description 7
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- 229920000642 polymer Polymers 0.000 description 6
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- WPYMKLBDIGXBTP-UHFFFAOYSA-N benzoic acid Chemical compound OC(=O)C1=CC=CC=C1 WPYMKLBDIGXBTP-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000004064 recycling Methods 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 3
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
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- HIXDQWDOVZUNNA-UHFFFAOYSA-N 2-(3,4-dimethoxyphenyl)-5-hydroxy-7-methoxychromen-4-one Chemical compound C=1C(OC)=CC(O)=C(C(C=2)=O)C=1OC=2C1=CC=C(OC)C(OC)=C1 HIXDQWDOVZUNNA-UHFFFAOYSA-N 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical class CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 1
- IGFHQQFPSIBGKE-UHFFFAOYSA-N Nonylphenol Natural products CCCCCCCCCC1=CC=C(O)C=C1 IGFHQQFPSIBGKE-UHFFFAOYSA-N 0.000 description 1
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Abstract
The invention relates to a method for recovering N, N-dimethylacetamide from a multi-component solution system. The method comprises (1) mixing a multi-component solution system with a composite inorganic compound composed of alkali metal hydroxide and alkali metal oxide to form a mixed system; (2) Carrying out solid-liquid separation on the mixed system obtained in the step (1) to obtain a solid material and a liquid material respectively; (3) Rectifying the liquid material obtained in the step (2) to recover the N, N-dimethylacetamide. The process is simple and controllable in operation, high in operation elasticity, capable of effectively separating the ternary solution completely and independently, and high in purity and overall recovery rate of the obtained N, N-dimethylacetamide.
Description
Technical Field
The invention belongs to the field of recovery of chemical mixed solutions, and particularly relates to a method for recovering N, N-dimethylacetamide from a multi-component solution system.
Background
N, N-dimethylacetamide, english DMAC for short, is a colorless transparent aprotic polar solvent, has low corrosiveness and toxicity, has a conventional boiling point of 166 ℃, can be mixed with water, alcohol, ester, ketone, ether, benzene, liquid alkane, aromatic compound and other solutions, is an important chemical solvent, has very important positions in the fields of medicines and pesticides, and is an important solvent in the preparation raw materials of a plurality of new medicines and the pesticide synthesis process. Meanwhile, the high-molecular polymer modified polypropylene has good dissolving capacity to high-molecular polymers and the like, so that the high-molecular polymer modified polypropylene is widely applied to the preparation processes of polymer spinning, fiber forming, hollow fiber membranes and the like, and is also applied to the coating industry, and is often used as a paint remover and a paint scavenger.
With the substitution of N, N-dimethylacetamide, N-dimethylformamide with large odor is easily decomposed, and a large amount of N, N-dimethylacetamide wastewater can be generated when the N, N-dimethylacetamide is used in a large amount in the chemical industry, in particular to the field of polymer spinning. For the treatment and recovery of the wastewater of the N, N-dimethylacetamide, the prior art mainly comprises two methods, namely a direct rectification method, namely, the recovery of the N, N-dimethylacetamide in the wastewater by one or more rectification methods, such as patent documents CN 207210299U and CN102030672A. Another method is an extraction-rectification method, in which N, N-dimethylacetamide is first enriched from wastewater into an extractant with a low boiling point and specific heat capacity by means of extraction, and then N, N-dimethylacetamide is recovered from the extractant by means of rectification, as in patent documents CN101255122a and CN 105645501A. Compared with a pure rectification process, the process has more advantages in energy consumption, particularly when the wastewater containing low-concentration N, N-dimethylacetamide is treated, the lower the concentration is, the more obvious the energy consumption advantage of the process is. In view of the characteristics of N, N-dimethylacetamide wastewater generated by medicine, paint and polymer spinning, an extraction-rectification process is the most commonly used method.
The extractant which has been reported at present mainly comprises organic solvents such as chloroform, dichloromethane, nonylphenol, methyl ethyl ketone and the like, and mixed solvents of butanol or isobutanol and toluene or xylene are also reported. The research shows that the composite extractant using chloroform as the main extractant and salicylic acid solid as the auxiliary extractant has very good extraction capacity for N, N-dimethylacetamide in wastewater, and the extractant and the extraction process can greatly reduce the usage amount of the extractant. After extraction, a ternary composition of chloroform-salicylic acid-N, N-dimethylacetamide is mainly present in the extracted phase. There are few reports on the separation of the ternary system, and the traditional method is to separate the three components by a rectification method. However, there are several problems: firstly, salicylic acid is solid at normal temperature and is easy to separate out in the rectification process; salicylic acid has a higher boiling point and a more severe rectification condition. For this reason, separating the extracted phases to recover the N, N-dimethylacetamide product and obtaining two other extractants for recycling becomes a key constraint factor restricting the use of the above-mentioned complex extractant.
Disclosure of Invention
Aiming at the problems existing in the prior art, in particular to an extraction phase for extracting and recycling N, N-dimethylacetamide in wastewater by taking chloroform and salicylic acid as composite extractants, a method for recycling N, N-dimethylacetamide from the extraction phase is developed to recycle and obtain an N, N-dimethylacetamide product and regenerate other two extractants for recycling and reutilizing.
The technical scheme adopted by the invention is as follows:
a process for recovering N, N-dimethylacetamide from a multiple solution system comprising the steps of:
(1) Mixing the multi-element solution system with a composite inorganic compound composed of alkali metal hydroxide and alkali metal oxide to form a mixed system;
(2) Carrying out solid-liquid separation on the mixed system obtained in the step (1) to obtain a solid material and a liquid material respectively;
(3) Rectifying the liquid material obtained in the step (2) to recover the N, N-dimethylacetamide.
The purpose of contacting a complex inorganic compound composed of an alkali metal hydroxide and an alkali metal oxide with a multi-component solution system is to react the alkali metal hydroxide such as sodium hydroxide with an organic acid such as salicylic acid in a ternary system to generate alkali metal carboxylate such as sodium salicylate, which is insoluble in chloroform and can be precipitated from the chloroform system, and to avoid that the generated alkali metal carboxylate such as sodium salicylate is dissolved in the generated water to form a new phase, so that part of N, N-dimethylacetamide enters the water phase from the chloroform phase to cause the loss of N, N-dimethylacetamide, the water of reaction needs to be removed, and the alkali metal oxide is added for this purpose. And the alkali metal hydroxide generated by the reaction of the alkali metal oxide and water can continue to react with salicylic acid.
According to some embodiments of the invention, the multi-component solution system comprises a haloalkane, a fat-soluble organic acid, and N, N-dimethylacetamide. The haloalkane may be a chlorinated C1-C2 alkane, such as chloroform. The fat-soluble organic acid may be benzoic acid or hydroxy-substituted benzoic acids, such as salicylic acid.
According to some embodiments of the invention, the multi-component solution system comprises a haloalkane, a fat-soluble organic acid, and N, N-dimethylacetamide. The haloalkane may be a chlorinated C1-C2 alkane, such as chloroform. The fat-soluble organic acid may be benzoic acid or hydroxy-substituted benzoic acids, such as salicylic acid.
According to some embodiments of the invention, the multi-component solution system comprises chloroform, salicylic acid, and N, N-dimethylacetamide. According to some embodiments of the invention, the multi-component solution system consists essentially of chloroform, salicylic acid, and N, N-dimethylacetamide. According to some embodiments, the multiplex system is a ternary solution system consisting of chloroform, salicylic acid, and N, N-dimethylacetamide. The term essentially means that the total amount of chloroform, salicylic acid and N, N-dimethylacetamide is more than 95wt%, preferably more than 98wt%, more preferably more than 99wt% of the total amount of the ternary solution system.
According to some embodiments of the invention, the multi-component system is derived from an extraction phase generated by extracting and recovering N, N-dimethylacetamide in wastewater by using chloroform and salicylic acid as a complex extractant.
According to some embodiments of the invention, the mass ratio of the haloalkane, the fat-soluble organic acid and the N, N-dimethylacetamide in the multi-element solution system is (50-90): 5-25.
According to some embodiments of the invention, in the multi-element solution system, chloroform: salicylic acid: the mass ratio of the N, N-dimethylacetamide is (50-90): 5-25. According to some embodiments of the invention, the alkali metal hydroxide is sodium hydroxide.
According to some embodiments of the invention, the alkali metal oxide is sodium oxide.
According to some embodiments of the invention, the mass ratio of the alkali metal hydroxide to the alkali metal oxide in the composite inorganic compound is (5-50): (50-95). In the initial stage of the step (1), alkali metal hydroxide, preferably sodium hydroxide, is reacted with organic acid, preferably salicylic acid, to form carboxylate and water, and the formed water is reacted with alkali metal oxide, preferably sodium oxide, to form alkali metal hydroxide in a relatively high proportion. The above ratio range is the optimum ratio. In some embodiments, the mass ratio of alkali metal hydroxide to alkali metal oxide in the composite inorganic compound is from 5:95 to 35:65. In some embodiments, the complex inorganic compound is preferably sodium hydroxide. When the reaction proceeds smoothly, it is essentially alkali metal oxide, and thus the mass ratio of alkali metal hydroxide to alkali metal oxide in the composite inorganic compound is 10:90 to 25:75.
According to some embodiments of the invention, the amount of the compound inorganic compound added is 1% -5% of the mass of the multi-element solution system. According to some embodiments of the present invention, when the ratio of the complex inorganic compound is excessively low, it may cause a part of salicylic acid to remain in the chloroform phase without forming sodium salicylate, resulting in insufficient recovery of salicylic acid. When the ratio of the added amount is too high, waste of inorganic compounds is caused, resources are not effectively utilized, and the use amount of the pickling step is increased. Within the above range, an optimum ratio is obtained. In addition, the existence of the alkaline washing step enables the solution phase of the treated chloroform and the treated N, N-dimethylacetamide to show a certain slight alkalinity, so that the decomposition of the N, N-dimethylacetamide in the subsequent rectification process can be effectively reduced, and the recovery rate of the N, N-dimethylacetamide is improved.
According to some embodiments of the invention, the solid-liquid separation in step (2) may be performed by centrifugation to separate out precipitated solids and excess complex inorganic compounds. After the addition of the complex inorganic compound, the single ternary homogeneous system of chloroform-salicylic acid-N, N-dimethylacetamide becomes turbid, partly due to the excessive complex inorganic compound and partly due to the fact that sodium salicylate is insoluble in chloroform phase. Sodium salicylate and composite inorganic compound solid can be obtained by adopting a centrifugal separation mode.
According to some embodiments of the invention, the rectifying of step (3) comprises a first rectification for recovering chloroform and a second rectification for recovering N, N-dimethylacetamide.
According to some embodiments of the invention, the rectification is used for treating the liquid material obtained in step (2). The liquid material obtained through the step (2) mainly comprises chloroform and N, N-dimethylacetamide. Chloroform with boiling point lower than that of N, N-dimethylacetamide is first rectified in the tower top, and the tower bottom is rectified for the second time to obtain high purity N, N-dimethylacetamide product in the tower top.
According to some embodiments of the invention, the first distillation is operated at a pressure of 0.25atm to 1atm, preferably 0.5 atm to 1atm, more preferably 0.5 atm to 0.75atm, and a reflux ratio of 0.25 to 4, preferably 0.25 to 2, more preferably 0.25 to 1, with the bottoms temperature being controlled at 120 ℃ to 166 ℃. The purpose of the first rectification is to remove and recover chloroform, when the operating pressure is too high, the temperature of the tower bottom of one tower is too high, the decomposition of N, N-dimethylacetamide is caused, and the recovery rate is reduced. On the other hand, when the operation pressure is too low, the boiling point of chloroform becomes low, and a cold source having a lower temperature is required for overhead condensation, resulting in an increase in cost. Thus, moderate operating pressures are suitable. And because the boiling points of chloroform and N, N-dimethylacetamide are greatly different, chloroform can be completely distilled out from the top of the tower under the condition of low reflux ratio.
According to some embodiments of the invention, the second rectification is operated at a pressure of 0.25atm to 1atm, preferably 0.25atm to 0.75atm, more preferably 0.25atm to 0.5atm, and at a reflux ratio of 0.5 to 8, preferably 1 to 4, more preferably 2 to 4, and the overhead temperature is controlled at 120 ℃ to 166 ℃. The purpose of the second rectification is to recover the N, N-dimethylacetamide product with high purity. Under the condition of higher vacuum degree, the temperature of the whole tower can be effectively reduced, and the decomposition of N, N-dimethylacetamide caused by high temperature is reduced. Meanwhile, the higher the reflux ratio is, the higher the purity of the obtained N, N-dimethylacetamide product is, but too high reflux ratio also increases the energy consumption in the rectification process. For this reason, a moderate reflux ratio is suitable. Finally, the N, N-dimethylacetamide product with high purity can be obtained at the top of the second rectification tower.
According to some embodiments of the invention, the method further comprises the steps of:
(4) Acidifying the solid material obtained in step (2) to obtain an acidified product, preferably salicylic acid.
According to some embodiments of the invention, the acidification treatment is mixing the solid material in water with an inorganic acid solution, preferably hydrochloric acid. According to some embodiments of the invention, the solid material separated in step (2) is dissolved in water, and when the mineral acid is added thereto, the reaction between strong acid and strong base is first carried out to form salt and water, and when the mineral acid is further added, the carboxylate salt, preferably sodium salicylate, is reduced to salicylic acid. Salicylic acid, however, has very little solubility in water and is insoluble in water, and therefore precipitates from the aqueous phase. Preferably, the acid solution is used in an amount of 3 to 6 times by weight the amount of the complex inorganic compound. The addition amount of the inorganic acid solution is required to be determined according to the addition amount of the compound inorganic compound, and when the addition amount of the inorganic acid solution is small, part of sodium salicylate can not be changed into salicylic acid and is separated out from the water phase, so that the salicylic acid is not fully recovered. When the adding amount of the inorganic acid liquid is too large, the waste of acid resources is caused, and a large amount of acid concentrated acid wastewater is generated.
Through the steps, the ternary solvent system can be separated, the purity and the recovery rate of the obtained N, N-dimethylacetamide product are high, the chloroform and the salicylic acid serving as the other two solvents can be recycled, and the N, N-dimethylacetamide wastewater can be continuously treated as an extractant.
The method can effectively and completely separate ternary components to obtain the high-purity N, N-dimethylacetamide product. The whole process is simple and controllable, and is an efficient separation method.
Drawings
Fig. 1 shows a method for recovering N, N-dimethylacetamide from a ternary solution system, wherein ① and ③ represent a basic wash out stirred tank and a pickling reduction stirred tank, respectively, ② and ④ represent centrifuges, ⑤ and ⑥ represent a first rectifying column and a second rectifying column, respectively. In the stream information, 1 represents a ternary solution system, 2 represents a compound inorganic compound, 3 represents a mixture obtained in the alkaline washing step, 4 represents a solid obtained in the alkaline washing step, 5 represents hydrochloric acid, 6 represents a solid obtained in the acid washing reduction step, that is, salicylic acid, 7 represents a clear liquid obtained in the acid washing reduction step, 8 represents a clear liquid obtained in the alkaline washing reduction step, 9 represents a top product of the first rectifying column, that is, chloroform, 10 represents a bottom product of the first rectifying column, 11 represents a top product of the second rectifying column, that is, N-dimethylacetamide, and 12 represents a bottom residual liquid of the second rectifying column.
Detailed Description
The invention is further illustrated by means of the following examples, which are not intended to limit the scope of the invention. The experimental methods, in which specific conditions are not noted in the following examples, were selected according to conventional methods and conditions, or according to the commercial specifications.
Example 1
The method comprises the steps of adding a ternary solution system of chloroform-salicylic acid-N, N-dimethylacetamide, wherein the mass ratio of substances is 90:5:5, adding the ternary solution system into an alkali washing precipitation stirring kettle, and simultaneously adding a composite inorganic compound with the mass being 1% of the mass of the ternary solution system, wherein the ratio of sodium hydroxide to sodium oxide in the composite inorganic compound is 5:95. After fully stirring, the mixture enters a centrifuge to obtain alkali-washed precipitated solid and alkali-washed precipitated clear liquid, wherein the alkali-washed precipitated solid is added into a pickling reduction stirring kettle, meanwhile, 36.5% hydrochloric acid solution with the mass which is 3 times of the adding amount of the compound inorganic compound is added, and the mixture is stirred and centrifuged to obtain pickling reduction solid, namely salicylic acid. And (3) performing secondary rectification on the obtained alkaline washing clear liquid, wherein the operating pressure of the first rectifying tower is 0.5atm, the reflux ratio is 0.25, the temperature of the tower bottom is controlled to be 141 ℃, and the light component, namely chloroform, is obtained at the tower top. And (3) continuously rectifying the tower bottom liquid of the first rectifying tower in a second rectifying tower, wherein the operating pressure of the second rectifying tower is 0.25atm, the reflux ratio is 8, the temperature of the tower top is controlled to be 120 ℃, and the corresponding fraction is collected to obtain the N, N-dimethylacetamide product. The purity of salicylic acid was 98.72%, the recovery rate was 98.5%, the purity of chloroform was 98.69%, the recovery rate was 95.7%, the purity of N, N-dimethylacetamide was 99.95%, and the recovery rate was 96.2%, as determined.
Example 2
The method comprises the steps of adding a ternary solution system of chloroform-salicylic acid-N, N-dimethylacetamide, wherein the mass ratio of substances is 80:10:10, adding the ternary solution system into an alkali washing precipitation stirring kettle, and simultaneously adding a compound inorganic compound with the mass being 4% of the mass of the ternary solution system, wherein the ratio of sodium hydroxide to sodium oxide in the compound inorganic compound is 50:50. After fully stirring, the mixture enters a centrifuge to obtain alkali-washed precipitated solid and alkali-washed precipitated clear liquid, wherein the alkali-washed precipitated solid is added into a pickling reduction stirring kettle, meanwhile, 36.5% hydrochloric acid solution with the mass which is 3 times of the adding amount of the compound inorganic compound is added, and the mixture is stirred and centrifuged to obtain pickling reduction solid, namely salicylic acid. And (3) performing secondary rectification on the obtained alkaline washing clear liquid, wherein the operating pressure of the first rectifying tower is 0.25atm, the reflux ratio is 1, the temperature of the tower bottom is controlled to be 120 ℃, and the light component, namely chloroform, is obtained at the tower top. And (3) continuously rectifying the tower bottom liquid of the first rectifying tower in a second rectifying tower, wherein the operating pressure of the second rectifying tower is 0.5atm, the reflux ratio is 4, the temperature of the tower top is controlled to be 141 ℃, and the corresponding fraction is collected to obtain the N, N-dimethylacetamide product. The purity of salicylic acid was 98.55%, the recovery rate was 99.1%, the purity of chloroform was 98.73%, the recovery rate was 95.2%, the purity of N, N-dimethylacetamide was 99.93%, and the recovery rate was 97.1%, as determined.
Example 3
The method comprises the steps of adding a ternary solution system of chloroform-salicylic acid-N, N-dimethylacetamide, wherein the mass ratio of substances is 70:15:15, adding the ternary solution system into an alkali washing precipitation stirring kettle, and simultaneously adding a composite inorganic compound with the mass being 3% of the ternary solution system, wherein the ratio of sodium hydroxide to sodium oxide in the composite inorganic compound is 10:90. After fully stirring, the mixture enters a centrifuge to obtain alkali-washed precipitated solid and alkali-washed precipitated clear liquid, wherein the alkali-washed precipitated solid is added into a pickling reduction stirring kettle, meanwhile, 36.5% hydrochloric acid solution with the mass which is 6 times of the addition amount of the compound inorganic compound is added, and the mixture is stirred and centrifuged to obtain pickling reduction solid, namely salicylic acid. And (3) performing secondary rectification on the obtained alkaline washing clear liquid, wherein the operating pressure of the first rectifying tower is 1atm, the reflux ratio is 4, the temperature of a tower bottom is controlled to be 166 ℃, and the light component, namely chloroform, is obtained at the tower top. And (3) continuously rectifying the tower bottom liquid of the first rectifying tower in a second rectifying tower, wherein the operating pressure of the second rectifying tower is 0.75atm, the reflux ratio is 2, the temperature of the tower top is controlled to be 156 ℃, and the corresponding fraction is collected to obtain the N, N-dimethylacetamide product. The purity of salicylic acid was 98.64%, the recovery rate was 98.7%, the purity of chloroform was 98.95%, the recovery rate was 94.0%, the purity of N, N-dimethylacetamide was 99.92%, and the recovery rate was 97.3%, as determined.
Example 4
The method comprises the steps of adding a ternary solution system of chloroform-salicylic acid-N, N-dimethylacetamide, wherein the mass ratio of substances is 60:20:20, adding the ternary solution system into an alkali washing precipitation stirring kettle, and simultaneously adding a composite inorganic compound with the mass being 4% of the mass of the ternary solution system, wherein the mass ratio of sodium hydroxide to sodium oxide in the composite inorganic compound is 20:80. After fully stirring, the mixture enters a centrifuge to obtain alkali-washed precipitated solid and alkali-washed precipitated clear liquid, wherein the alkali-washed precipitated solid is added into a pickling reduction stirring kettle, meanwhile, 36.5% hydrochloric acid solution with the mass being 4 times of the addition amount of the compound inorganic compound is added, and after stirring, the mixture is centrifuged to obtain pickling reduction solid, namely salicylic acid. And (3) performing secondary rectification on the obtained alkaline washing clear liquid, wherein the operating pressure of the first rectifying tower is 0.75atm, the reflux ratio is 2, the temperature of the tower bottom is controlled to be 156 ℃, and the light component, namely chloroform, is obtained at the tower top. And (3) continuously rectifying the tower bottom liquid of the first rectifying tower in a second rectifying tower, wherein the operating pressure of the second rectifying tower is 1atm, the reflux ratio is 1, the temperature of the tower top is controlled to be 166 ℃, and the corresponding fraction is collected to obtain the N, N-dimethylacetamide product. The purity of salicylic acid was 98.48%, the recovery rate was 98.6%, the purity of chloroform was 98.82%, the recovery rate was 95.1%, the purity of N, N-dimethylacetamide was 99.90%, and the recovery rate was 97.5%, as determined.
Example 5
The method comprises the steps of adding a ternary solution system of chloroform-salicylic acid-N, N-dimethylacetamide, wherein the mass ratio of substances is 50:25:25, adding the ternary solution system into an alkali washing precipitation stirring kettle, and simultaneously adding a composite inorganic compound with the mass being 5% of the mass of the ternary solution system, wherein the ratio of sodium hydroxide to sodium oxide in the composite inorganic compound is 5:95. After fully stirring, the mixture enters a centrifuge to obtain alkali-washed precipitated solid and alkali-washed precipitated clear liquid, wherein the alkali-washed precipitated solid is added into a pickling reduction stirring kettle, meanwhile, 36.5% hydrochloric acid solution with the mass being 4 times of the addition amount of the compound inorganic compound is added, and after stirring, the mixture is centrifuged to obtain pickling reduction solid, namely salicylic acid. And (3) performing secondary rectification on the obtained alkaline washing clear liquid, wherein the operating pressure of the first rectifying tower is 0.75atm, the reflux ratio is 1, the temperature of the tower bottom is controlled to be 156 ℃, and the light component, namely chloroform, is obtained at the tower top. And (3) continuously rectifying the tower bottom liquid of the first rectifying tower in a second rectifying tower, wherein the operating pressure of the second rectifying tower is 0.25atm, the reflux ratio is 2, the temperature of the tower top is controlled to be 120 ℃, and the corresponding fraction is collected to obtain the N, N-dimethylacetamide product. The purity of salicylic acid was measured to be 98.36%, the recovery rate was 98.2%, the purity of chloroform was 98.78%, the recovery rate was 95.3%, the purity of N, N-dimethylacetamide was 99.92%, and the recovery rate was 97.0%.
Example 6
The method comprises the steps of adding a ternary solution system of chloroform-salicylic acid-N, N-dimethylacetamide, wherein the mass ratio of substances is 90:5:5, adding the ternary solution system into an alkali washing precipitation stirring kettle, and simultaneously adding a compound inorganic compound with the mass being 2% of the mass of the ternary solution system, wherein the ratio of sodium hydroxide to sodium oxide in the compound inorganic compound is 30:70. After fully stirring, the mixture enters a centrifuge to obtain alkali-washed precipitated solid and alkali-washed precipitated clear liquid, wherein the alkali-washed precipitated solid is added into a pickling reduction stirring kettle, meanwhile, 36.5% hydrochloric acid solution with the mass which is 5 times of the addition amount of the compound inorganic compound is added, and after stirring, the mixture is centrifuged to obtain pickling reduction solid, namely salicylic acid. And (3) performing secondary rectification on the obtained alkaline washing clear liquid, wherein the operating pressure of the first rectifying tower is 0.75atm, the reflux ratio is 0.5, the temperature of the tower bottom is controlled to be 156 ℃, and the light component, namely chloroform, is obtained at the tower top. And (3) continuously rectifying the tower bottom liquid of the first rectifying tower in a second rectifying tower, wherein the operating pressure of the second rectifying tower is 0.25atm, the reflux ratio is 2, the temperature of the tower top is controlled to be 120 ℃, and the corresponding fraction is collected to obtain the N, N-dimethylacetamide product. The purity of salicylic acid was 98.53%, the recovery rate was 98.7%, the purity of chloroform was 98.72%, the recovery rate was 95.2%, the purity of N, N-dimethylacetamide was 99.92%, and the recovery rate was 97.1%, as determined.
Example 7
The method comprises the steps of adding a ternary solution system of chloroform-salicylic acid-N, N-dimethylacetamide, wherein the mass ratio of substances is 90:5:5, adding the ternary solution system into an alkali washing precipitation stirring kettle, and simultaneously adding a composite inorganic compound with the mass being 1% of the mass of the ternary solution system, wherein the ratio of sodium hydroxide to sodium oxide in the composite inorganic compound is 10:90. After fully stirring, the mixture enters a centrifuge to obtain alkali-washed precipitated solid and alkali-washed precipitated clear liquid, wherein the alkali-washed precipitated solid is added into a pickling reduction stirring kettle, meanwhile, 36.5% hydrochloric acid solution with the mass which is 3 times of the adding amount of the compound inorganic compound is added, and the mixture is stirred and centrifuged to obtain pickling reduction solid, namely salicylic acid. And (3) performing secondary rectification on the obtained alkaline washing clear liquid, wherein the operating pressure of the first rectifying tower is 1atm, the reflux ratio is 1, the temperature of the tower bottom is controlled to be 166 ℃, and the light component, namely chloroform, is obtained at the tower top. And (3) continuously rectifying the tower bottom liquid of the first rectifying tower in a second rectifying tower, wherein the operating pressure of the second rectifying tower is 0.25atm, the reflux ratio is 2, the temperature of the tower top is controlled to be 120 ℃, and the corresponding fraction is collected to obtain the N, N-dimethylacetamide product. The purity of salicylic acid was found to be 98.70%, the recovery rate was 98.6%, the purity of chloroform was found to be 98.79%, the recovery rate was found to be 94.7%, the purity of N, N-dimethylacetamide was found to be 99.91%, and the recovery rate was found to be 97.3%.
Example 8
The method comprises the steps of adding a ternary solution system of chloroform-salicylic acid-N, N-dimethylacetamide, wherein the mass ratio of substances is 90:5:5, adding the ternary solution system into an alkali washing precipitation stirring kettle, and simultaneously adding a composite inorganic compound with the mass being 1% of the mass of the ternary solution system, wherein the ratio of sodium hydroxide to sodium oxide in the composite inorganic compound is 10:90. After fully stirring, the mixture enters a centrifuge to obtain alkali-washed precipitated solid and alkali-washed precipitated clear liquid, wherein the alkali-washed precipitated solid is added into a pickling reduction stirring kettle, meanwhile, 36.5% hydrochloric acid solution with the mass which is 3 times of the adding amount of the compound inorganic compound is added, and the mixture is stirred and centrifuged to obtain pickling reduction solid, namely salicylic acid. And (3) performing secondary rectification on the obtained alkaline washing clear liquid, wherein the operating pressure of the first rectifying tower is 1atm, the reflux ratio is 1, the temperature of the tower bottom is controlled to be 166 ℃, and the light component, namely chloroform, is obtained at the tower top. And (3) continuously rectifying the tower bottom liquid of the first rectifying tower in a second rectifying tower, wherein the operating pressure of the second rectifying tower is 0.25atm, the reflux ratio is 4, the temperature of the tower top is controlled to be 120 ℃, and the corresponding fraction is collected to obtain the N, N-dimethylacetamide product. The purity of salicylic acid was 98.68%, the recovery rate was 98.4%, the purity of chloroform was 98.78%, the recovery rate was 94.5%, the purity of N, N-dimethylacetamide was 99.94%, and the recovery rate was 96.9%, as determined.
In the present invention, the purities of chloroform and N, N-dimethylacetamide were detected by HPLC, and the purity of salicylic acid was detected by an ultraviolet spectrophotometer.
Comparative example 1
The method comprises the steps of adding a ternary solution system of chloroform-salicylic acid-N, N-dimethylacetamide, wherein the mass ratio of substances is 90:5:5, into an alkali washing precipitation stirring kettle, and simultaneously adding a compound inorganic compound with the mass being 1% of that of the ternary solution system, wherein the compound inorganic compound only contains sodium hydroxide. After fully stirring, the mixture enters a centrifuge to obtain alkali-washed precipitated solid and alkali-washed precipitated clear liquid, wherein the alkali-washed precipitated solid is added into a pickling reduction stirring kettle, meanwhile, 36.5% hydrochloric acid solution with the mass which is 3 times of the adding amount of the compound inorganic compound is added, and the mixture is stirred and centrifuged to obtain pickling reduction solid, namely salicylic acid. And (3) performing secondary rectification on the obtained alkaline washing clear liquid, wherein the operating pressure of the first rectifying tower is 0.5atm, the reflux ratio is 0.25, the temperature of the tower bottom is controlled to be 141 ℃, and the light component, namely chloroform, is obtained at the tower top. And (3) continuously rectifying the tower bottom liquid of the first rectifying tower in a second rectifying tower, wherein the operating pressure of the second rectifying tower is 0.25atm, the reflux ratio is 8, the temperature of the tower top is controlled to be 120 ℃, and the corresponding fraction is collected to obtain the N, N-dimethylacetamide product. The purity of salicylic acid was found to be 98.41%, the recovery rate was 83.1%, the purity of chloroform was found to be 97.21%, the recovery rate was found to be 95.3%, the purity of N, N-dimethylacetamide was found to be 99.68%, and the recovery rate was found to be 94.8%.
Example 9
The method comprises the steps of adding a ternary solution system of chloroform-salicylic acid-N, N-dimethylacetamide, wherein the mass ratio of substances is 90:5:5, adding the ternary solution system into an alkali washing precipitation stirring kettle, and simultaneously adding a composite inorganic compound with the mass being 1% of the mass of the ternary solution system, wherein the ratio of sodium hydroxide to sodium oxide in the composite inorganic compound is 50:50. After fully stirring, the mixture enters a centrifuge to obtain alkali-washed precipitated solid and alkali-washed precipitated clear liquid, wherein the alkali-washed precipitated solid is added into a pickling reduction stirring kettle, meanwhile, 36.5% hydrochloric acid solution with the mass which is 3 times of the adding amount of the compound inorganic compound is added, and the mixture is stirred and centrifuged to obtain pickling reduction solid, namely salicylic acid. And (3) performing secondary rectification on the obtained alkaline washing clear liquid, wherein the operating pressure of the first rectifying tower is 0.5atm, the reflux ratio is 0.25, the temperature of the tower bottom is controlled to be 141 ℃, and the light component, namely chloroform, is obtained at the tower top. And (3) continuously rectifying the tower bottom liquid of the first rectifying tower in a second rectifying tower, wherein the operating pressure of the second rectifying tower is 0.25atm, the reflux ratio is 8, the temperature of the tower top is controlled to be 120 ℃, and the corresponding fraction is collected to obtain the N, N-dimethylacetamide product. The purity of salicylic acid was determined to be 98.62%, the recovery rate was determined to be 85.2%, the purity of chloroform was determined to be 97.38%, the recovery rate was determined to be 95.4%, the purity of N, N-dimethylacetamide was determined to be 99.75%, and the recovery rate was determined to be 95.0%.
Example 10
The method comprises the steps of adding a ternary solution system of chloroform-salicylic acid-N, N-dimethylacetamide, wherein the mass ratio of substances is 90:5:5, adding the ternary solution system into an alkali washing precipitation stirring kettle, and simultaneously adding a composite inorganic compound with the mass being 1% of the mass of the ternary solution system, wherein the ratio of sodium hydroxide to sodium oxide in the composite inorganic compound is 30:70. After fully stirring, the mixture enters a centrifuge to obtain alkali-washed precipitated solid and alkali-washed precipitated clear liquid, wherein the alkali-washed precipitated solid is added into a pickling reduction stirring kettle, meanwhile, 36.5% hydrochloric acid solution with the mass which is 3 times of the adding amount of the compound inorganic compound is added, and the mixture is stirred and centrifuged to obtain pickling reduction solid, namely salicylic acid. And (3) performing secondary rectification on the obtained alkaline washing clear liquid, wherein the operating pressure of the first rectifying tower is 0.5atm, the reflux ratio is 0.25, the temperature of the tower bottom is controlled to be 141 ℃, and the light component, namely chloroform, is obtained at the tower top. And (3) continuously rectifying the tower bottom liquid of the first rectifying tower in a second rectifying tower, wherein the operating pressure of the second rectifying tower is 0.25atm, the reflux ratio is 8, the temperature of the tower top is controlled to be 120 ℃, and the corresponding fraction is collected to obtain the N, N-dimethylacetamide product. The purity of salicylic acid was found to be 98.66%, the recovery rate was 91.2%, the purity of chloroform was 98.10%, the recovery rate was 95.5%, the purity of N, N-dimethylacetamide was 99.81%, and the recovery rate was 95.3%.
Example 11
The method comprises the steps of adding a ternary solution system of chloroform-salicylic acid-N, N-dimethylacetamide, wherein the mass ratio of substances is 90:5:5, adding the ternary solution system into an alkali washing precipitation stirring kettle, and simultaneously adding a composite inorganic compound with the mass being 1% of the mass of the ternary solution system, wherein the ratio of sodium hydroxide to sodium oxide in the composite inorganic compound is 20:80. After fully stirring, the mixture enters a centrifuge to obtain alkali-washed precipitated solid and alkali-washed precipitated clear liquid, wherein the alkali-washed precipitated solid is added into a pickling reduction stirring kettle, meanwhile, 36.5% hydrochloric acid solution with the mass which is 3 times of the adding amount of the compound inorganic compound is added, and the mixture is stirred and centrifuged to obtain pickling reduction solid, namely salicylic acid. And (3) performing secondary rectification on the obtained alkaline washing clear liquid, wherein the operating pressure of the first rectifying tower is 0.5atm, the reflux ratio is 0.25, the temperature of the tower bottom is controlled to be 141 ℃, and the light component, namely chloroform, is obtained at the tower top. And (3) continuously rectifying the tower bottom liquid of the first rectifying tower in a second rectifying tower, wherein the operating pressure of the second rectifying tower is 0.25atm, the reflux ratio is 8, the temperature of the tower top is controlled to be 120 ℃, and the corresponding fraction is collected to obtain the N, N-dimethylacetamide product. The purity of salicylic acid was 98.68%, the recovery rate was 95.8%, the purity of chloroform was 98.35%, the recovery rate was 95.6%, the purity of N, N-dimethylacetamide was 99.88%, and the recovery rate was 95.8%, as determined.
Example 12
The method comprises the steps of adding a ternary solution system of chloroform-salicylic acid-N, N-dimethylacetamide, wherein the mass ratio of substances is 90:5:5, adding the ternary solution system into an alkali washing precipitation stirring kettle, and simultaneously adding a composite inorganic compound with the mass being 1% of the mass of the ternary solution system, wherein the ratio of sodium hydroxide to sodium oxide in the composite inorganic compound is 10:90. After fully stirring, the mixture enters a centrifuge to obtain alkali-washed precipitated solid and alkali-washed precipitated clear liquid, wherein the alkali-washed precipitated solid is added into a pickling reduction stirring kettle, meanwhile, 36.5% hydrochloric acid solution with the mass which is 3 times of the adding amount of the compound inorganic compound is added, and the mixture is stirred and centrifuged to obtain pickling reduction solid, namely salicylic acid. And (3) performing secondary rectification on the obtained alkaline washing clear liquid, wherein the operating pressure of the first rectifying tower is 0.5atm, the reflux ratio is 0.25, the temperature of the tower bottom is controlled to be 141 ℃, and the light component, namely chloroform, is obtained at the tower top. And (3) continuously rectifying the tower bottom liquid of the first rectifying tower in a second rectifying tower, wherein the operating pressure of the second rectifying tower is 0.25atm, the reflux ratio is 8, the temperature of the tower top is controlled to be 120 ℃, and the corresponding fraction is collected to obtain the N, N-dimethylacetamide product. The purity of salicylic acid was measured to be 98.70%, the recovery rate was 98.1%, the purity of chloroform was 98.52%, the recovery rate was 95.7%, the purity of N, N-dimethylacetamide was 99.90%, and the recovery rate was 96.1%.
It should be noted that the above-described embodiments are only for explaining the present invention and do not limit the present invention in any way. The invention has been described with reference to exemplary embodiments, but it is understood that the words which have been used are words of description and illustration, rather than words of limitation. Modifications may be made to the invention as defined in the appended claims, and the invention may be modified without departing from the scope and spirit of the invention. Although the invention is described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, as the invention extends to all other means and applications which perform the same function.
Claims (15)
1. A process for recovering N, N-dimethylacetamide from a multiple solution system comprising the steps of:
(1) Mixing the multi-element solution system with a composite inorganic compound composed of alkali metal hydroxide and alkali metal oxide to form a mixed system;
(2) Carrying out solid-liquid separation on the mixed system obtained in the step (1) to obtain a solid material and a liquid material respectively;
(3) Rectifying the liquid material obtained in the step (2) to recover N, N-dimethylacetamide;
the multi-element solution system comprises chloroform, salicylic acid and N, N-dimethylacetamide;
The rectification in the step (3) comprises a first rectification and a second rectification, wherein the first rectification is used for recovering chloroform, and the second rectification is used for recovering N, N-dimethylacetamide;
The total amount of chloroform, salicylic acid and N, N-dimethylacetamide accounts for more than 95 weight percent of the total amount of the multi-element solution system;
In the multi-element solution system, chloroform: salicylic acid: the mass ratio of the N, N-dimethylacetamide is (50-90): 5-25.
2. The method of claim 1, wherein the multiple solution system is a ternary solution system consisting of chloroform, salicylic acid, and N, N-dimethylacetamide.
3. The method according to claim 1, wherein the multi-element solution system is derived from an extraction phase generated by extracting and recovering the N, N-dimethylacetamide in the wastewater by using chloroform and salicylic acid as a composite extractant.
4. A method according to any one of claims 1 to 3, wherein the mass ratio of alkali metal hydroxide to alkali metal oxide in the composite inorganic compound is (5 to 50): 50 to 95.
5. A method according to any one of claims 1 to 3, wherein the alkali metal hydroxide is sodium hydroxide and the alkali metal oxide is sodium oxide.
6. A method according to any one of claims 1 to 3, wherein the amount of the complex inorganic compound added is 1% to 5% by mass of the multi-component solution system.
7. A process according to any one of claims 1 to 3, wherein the first distillation is operated at a pressure of 0.25atm to 1atm, a reflux ratio of 0.25 to 4, and a temperature of the column bottoms is controlled at 120 ℃ to 166 ℃.
8. The method according to claim 7, wherein the operation pressure of the first distillation is 0.5 to 1atm, and/or the reflux ratio is 0.25 to 2.
9. The method according to claim 8, wherein the operation pressure of the first rectification is 0.75 to 1atm, and/or the reflux ratio is 0.25 to 1.
10. A process according to any one of claims 1 to 3, wherein the operating pressure of the second rectification is from 0.25atm to 1atm, the reflux ratio is from 0.5 to 8, and the overhead temperature is controlled to be from 120 ℃ to 166 ℃.
11. The method according to claim 10, wherein the operating pressure of the second rectification is 0.25-0.75atm, and/or the reflux ratio is 1-4.
12. The method of claim 11, wherein the second rectification is operated at a pressure of 0.25 to 0.5atm and a reflux ratio of 2 to 4.
13. A method according to any one of claims 1-3, further comprising the step of:
(4) And (3) acidizing the solid material obtained in the step (2) to obtain an acidized product.
14. The method of claim 13, wherein the acidifying treatment is mixing the solid material with an inorganic acid solution in water;
and/or, the acidification product is salicylic acid.
15. The method of claim 14, wherein the mineral acid is selected from the group consisting of hydrochloric acid;
And/or the acid liquid is used in an amount which is 3 to 6 times the amount of the compound inorganic compound by weight.
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