CN112079746A - Purification process and catalytic hydrogenation process of isophthalonitrile - Google Patents
Purification process and catalytic hydrogenation process of isophthalonitrile Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 46
- 238000000746 purification Methods 0.000 title claims abstract description 37
- 238000009903 catalytic hydrogenation reaction Methods 0.000 title claims abstract description 29
- LAQPNDIUHRHNCV-UHFFFAOYSA-N isophthalonitrile Chemical compound N#CC1=CC=CC(C#N)=C1 LAQPNDIUHRHNCV-UHFFFAOYSA-N 0.000 title claims abstract description 26
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims abstract description 176
- FDLQZKYLHJJBHD-UHFFFAOYSA-N [3-(aminomethyl)phenyl]methanamine Chemical compound NCC1=CC=CC(CN)=C1 FDLQZKYLHJJBHD-UHFFFAOYSA-N 0.000 claims abstract description 52
- 239000003054 catalyst Substances 0.000 claims abstract description 33
- 239000002351 wastewater Substances 0.000 claims abstract description 27
- 239000000463 material Substances 0.000 claims abstract description 22
- 239000012535 impurity Substances 0.000 claims abstract description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 75
- 238000006243 chemical reaction Methods 0.000 claims description 31
- 239000012153 distilled water Substances 0.000 claims description 27
- 238000005406 washing Methods 0.000 claims description 27
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 24
- 239000000243 solution Substances 0.000 claims description 19
- 238000003756 stirring Methods 0.000 claims description 19
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 18
- 238000010438 heat treatment Methods 0.000 claims description 18
- 238000001816 cooling Methods 0.000 claims description 15
- 239000000047 product Substances 0.000 claims description 13
- 239000012043 crude product Substances 0.000 claims description 12
- 238000001914 filtration Methods 0.000 claims description 9
- NPXOKRUENSOPAO-UHFFFAOYSA-N Raney nickel Chemical compound [Al].[Ni] NPXOKRUENSOPAO-UHFFFAOYSA-N 0.000 claims description 7
- 229910000564 Raney nickel Inorganic materials 0.000 claims description 7
- 239000011259 mixed solution Substances 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- 238000002425 crystallisation Methods 0.000 claims description 4
- 230000008025 crystallization Effects 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 4
- 239000002904 solvent Substances 0.000 claims description 4
- 238000000967 suction filtration Methods 0.000 claims description 4
- PAQVSWFCADWSLB-UHFFFAOYSA-N 3-cyanobenzamide Chemical compound NC(=O)C1=CC=CC(C#N)=C1 PAQVSWFCADWSLB-UHFFFAOYSA-N 0.000 claims description 3
- 239000007868 Raney catalyst Substances 0.000 claims description 3
- 239000012752 auxiliary agent Substances 0.000 claims description 3
- 238000007599 discharging Methods 0.000 claims description 3
- 239000004615 ingredient Substances 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims description 3
- 230000001502 supplementing effect Effects 0.000 claims description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 2
- 229910052739 hydrogen Inorganic materials 0.000 claims description 2
- 239000001257 hydrogen Substances 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- 238000005086 pumping Methods 0.000 claims description 2
- 238000000926 separation method Methods 0.000 claims 2
- 238000004519 manufacturing process Methods 0.000 abstract description 13
- 239000002994 raw material Substances 0.000 abstract description 9
- 238000005265 energy consumption Methods 0.000 abstract description 7
- 238000005516 engineering process Methods 0.000 abstract description 6
- 238000001035 drying Methods 0.000 abstract description 4
- 230000009286 beneficial effect Effects 0.000 abstract 1
- 239000000126 substance Substances 0.000 abstract 1
- 230000008929 regeneration Effects 0.000 description 11
- 238000011069 regeneration method Methods 0.000 description 11
- 230000007547 defect Effects 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 230000008901 benefit Effects 0.000 description 4
- 238000011084 recovery Methods 0.000 description 4
- 150000003335 secondary amines Chemical class 0.000 description 4
- CMQCNTNASCDNGR-UHFFFAOYSA-N toluene;hydrate Chemical compound O.CC1=CC=CC=C1 CMQCNTNASCDNGR-UHFFFAOYSA-N 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 238000005119 centrifugation Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012795 verification Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- QIRSDXBXWUTMRE-UHFFFAOYSA-N benzylcyanamide Chemical compound N#CNCC1=CC=CC=C1 QIRSDXBXWUTMRE-UHFFFAOYSA-N 0.000 description 1
- 238000003889 chemical engineering Methods 0.000 description 1
- 239000007810 chemical reaction solvent Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000013505 freshwater Substances 0.000 description 1
- 238000005984 hydrogenation reaction Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000000638 solvent extraction Methods 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
- 238000012418 validation experiment Methods 0.000 description 1
- 238000003809 water extraction Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C253/00—Preparation of carboxylic acid nitriles
- C07C253/32—Separation; Purification; Stabilisation; Use of additives
- C07C253/34—Separation; Purification
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
- C07C209/44—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of carboxylic acids or esters thereof in presence of ammonia or amines, or by reduction of nitriles, carboxylic acid amides, imines or imino-ethers
- C07C209/48—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of carboxylic acids or esters thereof in presence of ammonia or amines, or by reduction of nitriles, carboxylic acid amides, imines or imino-ethers by reduction of nitriles
Abstract
The invention belongs to the field of chemical industry, and particularly relates to a purification process and a catalytic hydrogenation process of isophthalonitrile, aiming at reducing the content of IPN impurities and enabling the IPN purification process and the MXDA production process to be connected in front and back so as to achieve the purpose of comprehensively improving the process technology. The purification process of isophthalonitrile provided by the invention comprises two steps of (S1) primary purification and (S2) reuse of toluene and wastewater. On the basis, the invention further provides an IPN catalytic hydrogenation process, and particularly relates to MXDA prepared by catalytic hydrogenation with the IPN wet material generated in the isophthalonitrile purification process step (S2) as a raw material. The invention has the beneficial effects in many aspects, the content of the purified IPN can be improved to about 99.7 percent, and the content of the impurity CBA can be reduced to below 0.1 percent; the operations of centrifuging, drying and the like of the IPN wet material are avoided, and the labor intensity and the energy consumption are obviously reduced; the waste water discharge is obviously reduced; the catalyst application frequency is greatly increased in the process of preparing MXDA by IPN catalytic hydrogenation; the product quality is improved; the comprehensive cost is reduced.
Description
Technical Field
The invention belongs to the field of chemical engineering, and particularly relates to a purification process and a catalytic hydrogenation process of isophthalonitrile.
Background
Isophthalonitrile (hereinafter, IPN) is an important raw material for producing hydrogenated products, i.e., m-xylylenediamine (hereinafter, MXDA), which is widely used and is a main raw material for synthetic resins. In recent years, the sale amount of MXDA has been increasing year by year, and the market prospect has become more and more promising.
Although the existing relatively mature IPN production technology has stable process and reliable quality of the produced IPN, the existing IPN production technology has obvious defects, specifically, the purity of the product is not high, the content of m-cyanobenzamide (CBA for short) is high, the number of times of catalyst application in MXDA production is influenced, the trapping equipment is huge, the amount of wastewater is large, about 10 tons of wastewater per ton of IPN is required, the product needs to be centrifuged and dried, the labor intensity is high, and the like. At present, a relatively mature MXDA production process takes IPN as a raw material and Raney nickel as a catalyst. The reaction effect and the product yield in the process are influenced by more factors, including the purity of the isophthalonitrile raw material, the catalyst, the reaction auxiliary agent, the reaction temperature, the reaction pressure, the reaction solvent and the like, wherein the Raney nickel catalyst is expensive, so the regeneration and the reuse of the catalyst directly influence the production cost of the product.
Before, the MXDA is produced by the traditional route, the technology is mature, the product quality is stable, but the process defects of few catalyst application times (only 4 batches of catalyst application), low equipment efficiency, high labor intensity and the like exist. With the gradual expansion of the productivity, the process defects are more prominent, so that the capital investment of a production device is too large, and the optimal economic benefit is difficult to achieve.
Therefore, it is desired to overcome the above process defects, so as to provide a more advanced and reasonable technology for the production expansion of IPN and MXDA.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a purification process and a catalytic hydrogenation process of isophthalonitrile, aiming at reducing the impurity content of IPN and combining an MXDA production process to connect the IPN purification process and the MXDA production process in a front-to-back manner, so that the purpose of comprehensively improving the process technology and improving the process defects is achieved, and particularly the application times of a catalyst are greatly increased.
In order to achieve the purpose, the invention is realized by the following technical scheme, which comprises the following steps:
(S1) first purification: mixing the IPN crude product with toluene, washing with distilled water for four times under a heating condition, then cooling, crystallizing, and filtering to separate out the toluene to obtain an IPN wet material;
(S2) reusing toluene and wastewater: washing MXDA recovered toluene with a mixed solution of wastewater generated by the first and second washing under heating conditions; then adding the mixed solution of the wastewater generated by the third and fourth water washes, recovering an IPN-toluene solution and an IPN crude product, washing with water under a heating condition, and removing a water layer; then washing twice with distilled water under heating condition; then cooling, crystallizing and filtering to separate out toluene to obtain an IPN wet material;
the MXDA recovered toluene refers to toluene recovered in a process of preparing MXDA through IPN catalytic hydrogenation; the recovered IPN-toluene solution is a toluene solution obtained by cooling, crystallizing and filtering a mixed solution of IPN.
Further, in the above-mentioned process for purifying isophthalonitrile, in the step (S1), the operation temperature for each washing with water and removing the water layer is preferably 85 ℃; the operating temperature for crystallization and suction filtration is preferably 10 ℃.
Further, in the above-mentioned process for purifying isophthalonitrile, in the step (S1), the mass ratio of the crude IPN, toluene, first distilled water, second distilled water, third distilled water, and fourth distilled water is preferably 80:440:320:160:160: 160.
Further, in the above-mentioned process for purifying isophthalonitrile, in the step (S2), the operation temperature for each washing with water and removing the water layer is preferably 85 ℃; the operating temperature for crystallization and suction filtration is preferably 10 ℃.
Further, in the above-mentioned process for purifying isophthalonitrile, in the step (S2), the mass ratio of the mixed solution of the waste water generated by the first and second water washes, the toluene recovered from MXDA, the IPN-toluene solution recovered, and the crude IPN is preferably 481:77.2:376.5: 66.3.
Further, in the purification process of isophthalonitrile, the content (wt) of IPN in the crude IPN product is 97-99%, and the content (wt) of the impurity, namely, the m-cyanobenzamide CBA is 1-2.5%.
Further, in the above-mentioned process for purifying isophthalonitrile, the step (S1) is preferably: putting 320 g of distilled water, 80 g of IPN crude product and 440 g of toluene into a 2000ml four-neck flask with a stirring pipe, a condensing pipe, a thermometer and jacket circulating hot water in sequence, heating to 85 ℃, keeping for 15 minutes, standing for 10 minutes, separating a lower water layer while the solution is hot, then adding 160 g of distilled water, similarly heating to 85 ℃, keeping for 15 minutes, standing for 10 minutes, separating a lower water layer while the solution is hot, washing with 160 g of distilled water twice under the same operation condition, finally standing, separating a water layer, putting an oil layer while the solution is hot into a 1000ml three-neck flask, cooling to 10 ℃ while stirring, and then stopping stirring, and pumping out the toluene by vacuum until the solution is nearly dry to obtain 126 g of IPN wet material;
the step (S2) is preferably: putting 481 g of the first and second combined waste water, 77.2 g of toluene recovered from MXDA, heating to 85 ℃, keeping for 15 minutes, standing for 10 minutes, removing a lower water layer while the mixture is hot, then adding 322 g of the third and fourth combined waste water, recovering 376.5 g of IPN-toluene solution and 66.3 g of IPN crude product, heating to 85 ℃, keeping for 15 minutes, standing for 10 minutes, removing a lower water layer while the mixture is hot, then adding 160 g of distilled water, heating to 85 ℃, keeping for 15 minutes, standing for 10 minutes, removing a lower water layer while the mixture is hot, washing with 160 g of distilled water twice under the same operation conditions, finally standing to separate a water layer, putting an oil layer while the oil layer is hot into a 1000ml three-neck flask, stirring, cooling to 10 ℃, stopping stirring, and vacuumizing to remove toluene to be nearly dry, 128 g of IPN wet material is obtained.
On the basis of the isophthalonitrile purification process, the invention further provides an IPN catalytic hydrogenation process, and the MXDA is prepared by taking the IPN wet material generated in the isophthalonitrile purification process (S2) as a raw material and performing catalytic hydrogenation.
Further, the IPN catalytic hydrogenation process takes Raney nickel as a catalyst, the reaction temperature is 65-70 ℃, and the hydrogen pressure is 5.5-6.0 MPa.
Further, the IPN catalytic hydrogenation process comprises the steps of putting a mixed ingredient of an IPN wet material, methylbenzene and methanol into an autoclave, putting a Raney nickel catalyst and a reaction auxiliary agent NaOH into the autoclave, sealing the autoclave, and adding H into the autoclave2Replacing the air in the kettle and then risingPressing to a certain pressure, starting stirring, preheating to 65 ℃, starting reaction, and continuously or intermittently supplementing H2Until the pressure no longer drops; after the reaction is finished, cooling, filtering and discharging; desolventizing and rectifying the reaction feed liquid to obtain MXDA; wherein, methanol: toluene (v/v) ═ 1:4, solvent: IPN (w/w) ═ 4:1, catalyst: 16.7 percent (wt%) of IPN, 1.65 percent (wt%) of 50 percent NaOH, 65-70 ℃ of reaction temperature and 5.5-6.0 MPa of reaction pressure.
Has the advantages that:
1. the IPN content can be improved to about 99.7 percent after being extracted by toluene-water for four times and purified by water washing, the CBA content can be reduced to below 0.1 percent, and the purification loss is about 0.88 percent.
2. The purification process is simple and convenient to operate, CBA is reliably removed because IPN is completely dissolved, extracted and washed by water, and operations such as centrifugation, drying and the like of wet IPN materials can be avoided because toluene is adopted for dissolving and extracting and the processes are related to the MXDA process, so that the labor intensity is greatly reduced, and the energy consumption is saved.
3. The purification process generates 7.5 tons of waste water per ton of purified IPN, and the discharge amount of the waste water is obviously reduced compared with the original process.
4. After IPN is purified, MXDA is prepared by catalytic hydrogenation, the catalyst can be continuously used for 16 batches, the catalyst can also be continuously used for 16 batches after regeneration, and the activity of the catalyst is not influenced. Therefore, through estimation, the yield can be improved by 17-20%, so that the equipment utilization rate is improved, and the catalyst regeneration cost and the labor intensity are reduced.
5. In the MXDA prepared by the purified IPN, the CBA is obviously reduced, namely the quality of the MXDA product is improved.
6. The raw material and energy consumption cost are integrated, and the purification process has certain cost advantage.
Drawings
FIG. 1 is a schematic diagram of a process flow and a material balance corresponding to the embodiment.
Detailed Description
The invention will be further illustrated by the following specific examples, which are given for the purpose of illustration only and are not intended to be limiting.
Examples
A purification process and a catalytic hydrogenation process of isophthalonitrile comprise the following steps. Wherein the purification and refinement of IPN comprises two parts (1) and (2), the flow diagram and the material balance (unit: g) are shown in figure 1, and the preparation of MXDA comprises a part (3).
(1) First purification
In a 2000ml four-necked flask with stirring, condenser, thermometer and jacket circulating hot water, 320 g of distilled water, 80 g of IPN and 440 g of industrial toluene were sequentially charged, heated to 85 ℃ and kept for 15 minutes, and left to stand for 10 minutes, the lower aqueous layer was separated while hot, then 160 g of distilled water was charged, similarly heated to 85 ℃ and kept for 15 minutes, and left to stand for 10 minutes, the lower aqueous layer was separated while hot, and under the same operating conditions, the mixture was washed twice with 160 g of distilled water. And finally, standing to separate out a water layer, putting the oil layer into a 1000ml three-neck flask while the oil layer is hot, slowly cooling to 10 ℃ while stirring, stopping stirring, and vacuumizing to remove the toluene till the toluene is nearly dry to obtain 126 g of wet material.
(2) Toluene and wastewater jacket
Into a 2000ml four-neck flask with stirring, condenser, thermometer and jacket circulating hot water, 481 g of the first and second combined waste water were put in succession, 77.2 g of toluene was recovered from MXDA, heated to 85 ℃, kept for 15 minutes, left to stand for 10 minutes, the lower water layer was removed while hot, 322 g of the third and fourth combined waste water was added, 376.5 g of IPN-toluene solution and 66.3 g of crude IPN were recovered, heated to 85 ℃, kept for 15 minutes, left to stand for 10 minutes, the lower water layer was removed while hot, 160 g of distilled water was added, heated to 85 ℃ likewise, kept for 15 minutes, left to stand for 10 minutes, the lower water layer was removed while hot, and washed twice with 160 g of distilled water under the same operating conditions. And finally, standing to separate a water layer, putting the oil layer into a 1000ml three-neck flask while the oil layer is hot, slowly cooling to 10 ℃ while stirring, stopping stirring, and vacuumizing to remove toluene till the toluene is nearly dry to obtain 128 g of wet material to be hydrogenated.
(3) Catalytic hydrogenation process
Putting the mixed ingredients of IPN wet material, toluene and methanol into an autoclave, then putting Raney nickel catalyst and reaction aidNaOH, then sealing the reaction kettle and using H2Replacing the air in the kettle, increasing the pressure to a certain pressure range, starting stirring, preheating to 65 ℃, starting reaction, and continuously or discontinuously supplementing H2Until the pressure no longer drops. And after the reaction is finished, cooling, filtering and discharging. And desolventizing and rectifying the reaction feed liquid to obtain MXDA. The specific parameters are as follows: 500ml reaction kettle, methanol: toluene (v/v) ═ 1:4, solvent: IPN (w/w) ═ 4:1, catalyst: 16.7 percent (wt%) of IPN, 1.65 percent (wt%) of 50 percent NaOH, 65-70 ℃ of reaction temperature and 5.5-6.0 MPa of reaction pressure.
Results and discussion
In this example, the purification yield of IPN was 98%, the total yield of MXDA was 85%, the recovery rate of toluene in the purification process of IPN was 98%, the recovery rate of methanol after hydrogenation reaction of IPN was 90%, and the recovery rate of toluene was 95%.
First, cost factor.
The cost of the purification and refinement of the IPN is low, and mainly comprises the one-time investment, material loss and energy consumption of the newly added equipment, and the specific accounting is as follows.
On a per ton basis, per finished IPN produced. The IPN purification loss is calculated as 1 percent, the unit price is calculated as 15000 yuan/ton, 10 kilograms of IPN are consumed, and the total amount is 150 yuan; the solubility of the toluene in water is 30 ℃ and 0.06 percent (wt), and considering the recovery of the toluene in the wastewater, the water loss of the toluene is about 5KG, and the unit price of the toluene is 8000 yuan/ton, and is 40 yuan; the purification process adds a certain energy cost.
The new equipment is shown in table 1 (to produce a refined IPN of 3000 tons/year).
TABLE 1 cost accounting for newly added equipment
The three wastes generated by the purification and refinement of IPN have simple components, low impurity content and relatively low processing cost, as shown in Table 2, in order to produce one ton of refined IPN.
TABLE 2 three wastes treatment
After the purification process is adopted to purify and refine the IPN, the operations of centrifuging, drying and the like of wet IPN materials can be saved, and a large amount of energy consumption is saved; after IPN is purified, catalytic hydrogenation is carried out, the number of times of catalyst application is increased from 4 to 16, the catalyst regeneration cost is obviously reduced, and in addition, the yield can be improved by about 1%.
The cost is reduced by comprehensively considering the influence factors and adopting the purification process for IPN.
The effect of the two-solvent extraction and washing process of toluene-water on the quality of IPN.
The content of industrial IPN is generally 97-99%, wherein CBA 1-2.5% is mainly contained, and the content of the IPN has direct influence on the reuse times of the catalyst. In the original MXDA production process, the number of times of catalyst application can only reach four, and regeneration treatment is needed to ensure that the content of the intermediate cyanobenzylamine of MXDA is less than 0.5% (which is a central control index, and impurities cannot be removed in refining), so that the content of MXDA is ensured to be more than 99%, the exertion of MXDA production capacity is greatly limited, the production cost is increased, and the labor intensity is enhanced. By purifying the IPN, the CBA content is reduced as much as possible to increase the number of times the catalyst is used.
The solubility of IPN in toluene was determined to be 17% (80 ℃) and in water was reported to be 0.7g/l (20 ℃) whereas the structure of CBA determines that it is slightly soluble in toluene and relatively soluble in water. In this example, the CBA content was significantly reduced by toluene extraction and water washing, as shown in Table 3.
TABLE 3 influence of toluene-water extraction wash on CBA removal in IPN
Note:
1. the toluene is used for extracting the first and second waste water from the 05-3-29 batches, and the third and fourth waste water from the 05-3-29 batches are directly used for the first water washing, and fresh water is used for the third water washing.
2. The average yield of the last three batches is 99.12%.
3. The CBA content in the IPN crude product has great influence on the washing result, if the CBA content in the crude product is less than 2 percent, the CBA content in the refined product can be less than 0.1 percent if the washing is carried out for four times, and the CBA content in the refined product can be less than 0.1 percent if the CBA content in the crude product is less than 0.8 percent if the washing is carried out for three times.
From the above table, it can be seen that the yield is only 95.01% when toluene is not extracted and wastewater is not used, the average yield after extraction and use can reach 99.12%, and the CBA can be reduced to about 0.1%.
And thirdly, the IPN purification influences the reuse times of the catalyst in the MXDA preparation by catalytic hydrogenation.
TABLE 4 comparative test results for the preparation of MXDA by catalytic hydrogenation of the unpurified IPN
Table 5 verification test results of preparing MXDA by IPN catalytic hydrogenation after purification
TABLE 6 test results of catalytic hydrogenation of IPN to MXDA after catalyst regeneration
Note:
1. table 4 the control experiment used 97.53% IPN and 2.13% CBA, and the validation experiment in table 5 and the regeneration experiment in table 6 used 99.73% IPN and 0.09% CBA.
2. The control test, the verification test and the regeneration test have the same process conditions and operation conditions except that the raw materials are different. Reaction conditions are as follows: 500ml reaction kettle, methanol: toluene (v/v) ═ 1:4, solvent: IPN (w/w) ═ 4:1, catalyst: 16.7 percent (wt%) of IPN, 1.65 percent (wt%) of 50 percent NaOH, 65-70 ℃ of reaction temperature and 5.5-6.0 MP of reaction pressure.
As can be seen from table 4, only four batches of IPN catalyst could be used without purification, and when the fifth batch was used, the major content decreased significantly, as was the case with the prior art. 5 batches had an average MXDA content of 94.31%, an average CBA content of 0.81%, an average secondary amine content of 3.61% and an average content of other impurities of 1.27%.
As can be seen from Table 5, after the IPN is purified, the catalyst can be continuously used in 16 batches, the average content of MXDA in the first 16 batches is 97.24%, the average content of CBA is 0.16%, and the average content of secondary amine is 2.12%. The average content of other impurities is 0.48%.
As can be seen from Table 6, the purified IPN, after catalyst regeneration, also can be continuously hydrogenated by 16 batches of catalytic hydrogenation, which indicates that the activity of the regenerated catalyst has no influence. The average content of MXDA in the first 16 batches was 96.57%, the average content of CBA was 0.59%, the average content of secondary amine was 1.72%, and the average content of other impurities was 1.12%.
As can be seen from tables 4, 5 and 6, after IPN is purified, the average MXDA content is increased by 2-3% compared with that of the control experiment through catalytic hydrogenation, and the CBA content and the secondary amine content are both reduced, which is undoubtedly of great help for improving the product yield and quality.
Fourthly, summarizing.
1. The IPN content can be improved to about 99.7 percent after being extracted by toluene-water for four times and purified by water washing, the CBA content can be reduced to below 0.1 percent, and the purification loss is about 0.88 percent.
2. The purification process is simple and convenient to operate, CBA is reliably removed because IPN is completely dissolved, extracted and washed by water, and operations such as centrifugation, drying and the like of wet IPN materials can be avoided because toluene is adopted for dissolving and extracting and the processes are related to the MXDA process, so that the labor intensity is greatly reduced, and the energy consumption is saved.
3. The purification process generates 7.5 tons of waste water per ton of purified IPN, and the discharge amount of the waste water is obviously reduced compared with the original process.
4. After IPN is purified, MXDA is prepared by catalytic hydrogenation, the catalyst can be continuously used for 16 batches, the catalyst can also be continuously used for 16 batches after regeneration, and the activity of the catalyst is not influenced. Therefore, through estimation, the yield can be improved by 17-20%, so that the equipment utilization rate is improved, and the catalyst regeneration cost and the labor intensity are reduced.
5. In the MXDA prepared by the purified IPN, the CBA is obviously reduced, namely the quality of the MXDA product is improved.
6. The raw material and energy consumption cost are integrated, and the purification process has certain cost advantage.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that modifications can be made by those skilled in the art without departing from the principle of the present invention, and these modifications should also be construed as the protection scope of the present invention.
Claims (10)
1. A process for purifying isophthalonitrile, which is characterized by comprising the following steps: the method comprises the following steps:
(S1) first purification: mixing the IPN crude product with toluene, washing with distilled water for four times under a heating condition, then cooling, crystallizing, and filtering to separate out the toluene to obtain an IPN wet material;
(S2) reusing toluene and wastewater: washing MXDA recovered toluene with a mixed solution of wastewater generated by the first and second washing under heating conditions; then adding the mixed solution of the wastewater generated by the third and fourth water washes, recovering an IPN-toluene solution and an IPN crude product, washing with water under a heating condition, and removing a water layer; then washing twice with distilled water under heating condition; then cooling, crystallizing and filtering to separate out toluene to obtain an IPN wet material;
the MXDA recovered toluene refers to toluene recovered in a process of preparing MXDA through IPN catalytic hydrogenation; the recovered IPN-toluene solution is a toluene solution obtained by cooling, crystallizing and filtering a mixed solution of IPN; marking isophthalonitrile as IPN; m-xylylenediamine was designated as MXDA.
2. The process for purifying isophthalonitrile according to claim 1, wherein: in the step (S1), the operation temperature of each time of washing and water layer separation is 85 ℃; the operating temperature for crystallization and suction filtration was 10 ℃.
3. The process for purifying isophthalonitrile according to claim 1, wherein: in the step (S1), the mass ratio of the crude IPN, toluene, first distilled water, second distilled water, third distilled water, and fourth distilled water is 80:440:320:160:160: 160.
4. The process for purifying isophthalonitrile according to claim 1, wherein: in the step (S2), the operation temperature of each time of washing and water layer separation is 85 ℃; the operating temperature for crystallization and suction filtration was 10 ℃.
5. The process for purifying isophthalonitrile according to claim 1, wherein: in the step (S2), the mass ratio of the mixed liquid of the wastewater generated by the first and second water washes, the toluene recovered from MXDA, the IPN-toluene solution recovered, and the crude IPN product was 481:77.2:376.5: 66.3.
6. The process for purifying isophthalonitrile according to claim 1, wherein: in the crude product of IPN, the content (wt) of IPN is 97-99%, and the content (wt) of the impurity, namely the m-cyanobenzamide CBA, is 1-2.5%.
7. The process for purifying isophthalonitrile according to any one of claims 1 to 6, wherein: the step (S1) is: putting 320 g of distilled water, 80 g of IPN crude product and 440 g of toluene into a 2000ml four-neck flask with a stirring pipe, a condensing pipe, a thermometer and jacket circulating hot water in sequence, heating to 85 ℃, keeping for 15 minutes, standing for 10 minutes, separating a lower water layer while the solution is hot, then adding 160 g of distilled water, similarly heating to 85 ℃, keeping for 15 minutes, standing for 10 minutes, separating a lower water layer while the solution is hot, washing with 160 g of distilled water twice under the same operation condition, finally standing, separating a water layer, putting an oil layer while the solution is hot into a 1000ml three-neck flask, cooling to 10 ℃ while stirring, and then stopping stirring, and pumping out the toluene by vacuum until the solution is nearly dry to obtain 126 g of IPN wet material;
the step (S2) is: putting 481 g of the first and second combined waste water, 77.2 g of toluene recovered from MXDA, heating to 85 ℃, keeping for 15 minutes, standing for 10 minutes, removing a lower water layer while the mixture is hot, then adding 322 g of the third and fourth combined waste water, recovering 376.5 g of IPN-toluene solution and 66.3 g of IPN crude product, heating to 85 ℃, keeping for 15 minutes, standing for 10 minutes, removing a lower water layer while the mixture is hot, then adding 160 g of distilled water, heating to 85 ℃, keeping for 15 minutes, standing for 10 minutes, removing a lower water layer while the mixture is hot, washing with 160 g of distilled water twice under the same operation conditions, finally standing to separate a water layer, putting an oil layer while the oil layer is hot into a 1000ml three-neck flask, stirring, cooling to 10 ℃, stopping stirring, and vacuumizing to remove toluene to be nearly dry, 128 g of IPN wet material is obtained.
8. An IPN catalytic hydrogenation process, which is characterized in that: preparing MXDA by catalytic hydrogenation starting from the IPN wet feed produced in the step (S2) of any one of claims 1 to 7.
9. The IPN catalytic hydrogenation process of claim 8, wherein: raney nickel is used as a catalyst, the reaction temperature is 65-70 ℃, and the hydrogen pressure is 5.5-6.0 MPa.
10. The IPN catalytic hydrogenation process of claim 8, wherein: putting the mixed ingredients of IPN wet material, toluene and methanol into a high-pressure kettle, then putting Raney nickel catalyst and reaction auxiliary agent NaOH, then sealing the reaction kettle, and using H2Replacing the air in the kettle, increasing the pressure to a certain pressure, starting stirring, preheating to 65 ℃, starting the reaction, and continuously or discontinuously supplementing H2Until the pressure no longer drops; after the reaction is finished, cooling, filtering and discharging; desolventizing and rectifying the reaction feed liquid to obtain MXDA; wherein, methanol: toluene (v/v) =1:4, solvent: IPN (w/w) =4:1, catalyst: IPN =16.7% (wt%), 50% NaOH: IPN =1.65 (wt%),the reaction temperature is 65-70 ℃, and the reaction pressure is 5.5-6.0 MPa.
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