Dehydration treatment method for toluene with high water content
By contacting high water content toluene with organic aluminum compounds under an inert atmosphere and combining with molecular sieve dehydration treatment, the problem of low toluene dehydration efficiency in the prior art is solved, and the toluene water content is rapidly reduced, suitable for large-scale processing and improving Productivity.
Patent Information
- Application Number
- CN202310777749.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-28
- Publication Date
- 2024-12-31
AI Technical Summary
The existing toluene dehydration method is difficult to effectively reduce the water content of high water content toluene in a short period of time, especially in large batch processing, which has problems such as low efficiency and difficulty in regeneration of desiccant.
In an inert atmosphere, a high water content toluene is contacted with an R-Al bond and an organoaluminum compound is carried out for the first dehydration treatment, followed by distillation or rectification, and then a second dehydration treatment is performed using a molecular sieve to reduce the toluene water content to below 20 ppm purpose.
It achieves rapid reduction of high water content toluene (above 100ppm), and the water content is reduced to below 20ppm. It is safe and simple to operate, suitable for large-scale processing, and improves process production efficiency.
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Abstract
Description
Technical Field
[0001] The present application relates to the technical field of solvent dehydration, and in particular to a dehydration treatment method for toluene with high water content. Background Art
[0002] As an important aromatic compound, toluene is now widely used as a solvent and high-octane gasoline additive. At the same time, as an important organic chemical raw material intermediate, its derivatives such as benzyl chloride, benzoate, epoxide, sulfonation products, etc. have also been widely used in the production of various fine chemicals such as dyes, pesticides, and medicines.
[0003] As an important indicator of organic solvents, water content usually has a great influence on organic chemical reactions. For some reactions that require anhydrous and oxygen-free environments, it is even a key factor in determining whether such reactions can proceed. Therefore, dehydration of organic solvents has become an important link in the field of chemical production.
[0004] For toluene, the most commonly used dehydration method is to soak it in a desiccant (such as 3A, 4A molecular sieves, activated alumina, silica gel, etc.) or to perform cyclic adsorption on a corresponding adsorption column. Although this method can obtain dehydrated toluene with a relatively low water content (less than 10 ppm) to a certain extent, it is not applicable to large quantities of toluene with a high water content (hundreds of kilograms and a water content higher than 100 ppm) because it is difficult to obtain the required low water content within an acceptable time and there is a problem of difficulty in regenerating a large amount of desiccant.
[0005] It is also a known solvent dehydration method to realize the dehydration of solvent by chemical reagent and water reaction. For example, it is known that in the presence of metallic sodium, a dehydration method for distilling water-containing toluene is carried out. However, due to the high risk of this method, it has been gradually banned. Therefore, for the treatment of a large amount of water-containing toluene, this method is not applicable. It is currently only applicable to scientific research institutions to process a small amount of toluene, and the obtained toluene water content is about 40ppm, and it is impossible to obtain toluene with a lower water content. CN104151146A discloses a dehydration method of an organic solvent realized by chemical reaction. Although it can be applied to the dehydration production of organic solvents in chemical enterprises, due to the need to use two kinds of reaction materials, the operation is relatively complicated, and the water content of the obtained dehydrated solvent is only less than 300ppm. In addition, calcium hydride, calcium oxide, phosphorus pentoxide, etc. are also commonly used chemical dehydrating agents.
[0006] Therefore, developing a simple, efficient and suitable dehydration method for large amounts of toluene with high water content is of great significance to the field of chemical production. Summary of the invention
[0007] The purpose of the present application is to provide a safe, simple and efficient toluene dehydration method, which is suitable for treating a large amount of toluene with a high water content, and can reduce the water content of toluene to below 20 ppm in a relatively short period of time, thereby greatly improving the production efficiency of the relevant process.
[0008] In order to achieve the above object, the present application provides a dehydration method for high-water-content toluene having a water content of at least 100 ppm, comprising the following steps:
[0009] 1) under an inert atmosphere, contacting the high water content toluene with an organoaluminum compound having at least one R-Al bond for a first dehydration treatment, wherein R represents an alkyl group;
[0010] 2) performing distillation or rectification simultaneously with step 1) or after step 1) to obtain partially dehydrated toluene; and
[0011] 3) contacting the partially dehydrated toluene with a molecular sieve for a second dehydration treatment to obtain dehydrated toluene, for example, dehydrated toluene with a water content of less than 20 ppm.
[0012] Compared with the existing toluene dehydration treatment method, the method of the present application can efficiently treat toluene with a water content of more than 100 ppm, or even as high as more than 400 ppm, and can reduce the water content of toluene to less than 20 ppm in a relatively short period of time. The operation is safe and simple, and is particularly suitable for large-scale (e.g., more than 100 L) treatment of toluene.
[0013] Other features and advantages of the present application will be described in detail in the subsequent detailed description. DETAILED DESCRIPTION
[0014] The specific implementation methods of the present application are described in detail below, but it should be noted that the protection scope of the present application is not limited by these specific implementation methods, but is determined by the claims in the appendix.
[0015] Any specific numerical value disclosed herein (including the endpoint of the numerical range) is not limited to the exact value of the numerical value, but should be understood to also cover values close to the exact value, such as all possible numerical values within the range of ±5% of the exact value. In addition, for the disclosed numerical range, the endpoint values of the range, the endpoint values and the specific point values in the range, and the specific point values can be arbitrarily combined to obtain one or more new numerical ranges, and these new numerical ranges should also be regarded as specifically disclosed herein.
[0016] Unless otherwise specified, the terms used herein have the same meaning as commonly understood by those skilled in the art. If a term is defined herein and its definition is different from the commonly understood meaning in the art, the definition herein shall prevail.
[0017] In this application, except for the contents clearly stated, any matters or items not mentioned are directly applicable to the aspects known in the art without any changes. Moreover, any embodiment described herein can be freely combined with one or more other embodiments described herein, and the technical solutions or technical ideas formed thereby are deemed to be part of the original disclosure or original record of this application, and should not be regarded as new contents not disclosed or anticipated herein, unless a person skilled in the art considers that the combination is obviously unreasonable.
[0018] All patent and non-patent literature, including but not limited to textbooks and journal articles, mentioned herein are incorporated herein by reference in their entirety.
[0019] The toluene dehydration treatment methods known in the prior art are usually only suitable for treating toluene with a water content of less than 100ppm, or even if toluene with a high water content can be treated, it is difficult to quickly reduce the water content of toluene to a desired level (e.g., less than 20ppm), and it is even more difficult to achieve efficient treatment of large quantities of toluene with high water content, such as reducing its water content to less than 20ppm within an acceptable time (e.g., within 14 days). The inventors of the present application unexpectedly discovered through extensive and in-depth research that under appropriate conditions, the use of high-boiling organoaluminum compounds can significantly reduce the water content of toluene without affecting the distillation of toluene, and then combined with a molecular sieve dehydration process, the water content of toluene can be reduced from more than 100ppm (even more than 400ppm) to less than 20ppm in a relatively short period of time, thereby completing the present invention.
[0020] As described above, the present application relates to a method for dehydrating high-water-content toluene having a water content of at least 100 ppm, comprising the following steps:
[0021] 1) under an inert atmosphere, contacting the toluene with a high water content with an organoaluminum compound having at least one R-A1 bond for a first dehydration treatment, wherein R represents an alkyl group;
[0022] 2) performing distillation or rectification simultaneously with step 1) or after step 1) to obtain partially dehydrated toluene; and
[0023] 3) contacting the partially dehydrated toluene with a molecular sieve for a second dehydration treatment to obtain dehydrated toluene, for example, dehydrated toluene with a water content of less than 20 ppm.
[0024] According to the present application, the high water content toluene has a water content of more than 100 ppm, for example, more than 130 ppm, more than 150 ppm, more than 200 ppm, more than 300 ppm or more than 400 ppm. In some specific embodiments, the water content of the high water content toluene is less than 2000 ppm, for example, less than 1000 ppm or less than 500 ppm.
[0025] In a preferred embodiment, the R group in the organoaluminum compound is C 1-8 Alkyl, preferably C 1-6 Alkyl groups such as methyl, ethyl, propyl, butyl, pentyl and hexyl include various isomeric forms thereof.
[0026] In a preferred embodiment, the organic aluminum compound has a boiling point higher than toluene and is selected from alkyl aluminum, alkyl aluminoxane, or a combination thereof.
[0027] In certain further preferred embodiments, the alkyl aluminum has a structure shown in general formula (I),
[0028] Al(R1)3 (I)
[0029] wherein each group R1 is independently selected from alkyl, alkoxy, halogen and amine, and at least one R1 group is an alkyl group, preferably C 1-8 Alkyl, more preferably C 1-6 Alkyl, particularly preferably C 1-4 Alkyl, such as methyl, ethyl, propyl and butyl, including various isomeric forms thereof. Further preferably, the alkoxy is C 1-8 Alkoxy, more preferably C 1-6 Alkoxy, particularly preferably C 1-4 Alkoxy, such as methoxy, ethoxy, propoxy and butoxy, including various isomeric forms thereof; the halogen is chlorine, bromine and / or iodine; the amine group has the structural formula -N(R')2, wherein each group R' is independently C 1-8 Alkyl, more preferably C 1-6 Alkyl, particularly preferably C 1-4 Alkyl groups, such as methyl, ethyl, propyl and butyl, include various isomeric forms thereof.
[0030] In some further preferred embodiments, the aluminoxane has a structure represented by general formula (II):
[0031] [-Al(R2)O-] n (II)
[0032] Wherein each group R2 is independently selected from C 1-8 Alkyl, preferably C 1-6 Alkyl, more preferably C1-4 Alkyl groups, such as methyl, ethyl, propyl and butyl, include various isomeric forms thereof; n is a positive integer, preferably 1-50.
[0033] In a further preferred embodiment, the organoaluminum compound is selected from methylaluminoxane (MAO), ethylaluminoxane (EAO), isobutylaluminoxane (IBAO), modified methylaluminoxane (MMAO), tri-n-hexylaluminum (Al( n C6H 13 )3) triisohexyl aluminum (Al( i C6H 13 )3) Tri-n-pentyl aluminum (Al( n C5H 11 )3) Triisopentyl aluminum (Al( i C5H 11 )3), diethylaluminum iodide (Al(CH3CH2)2I), diethylaluminum bromide (Al(CH3CH2)2Br), diethylaluminum chloride (Al(CH3CH2)2Cl), di-n-butylaluminum chloride (Al( n C4H9)2Cl), diisobutylaluminum chloride (Al( i C4H9)2Cl), diethyldiethylamine aluminum (Al(Et2N)Et2), N-ethyl-N-isopropylaminodimethylaluminum (Al( i PrNEt)(Me)2), or a combination thereof. Particularly preferably, the organoaluminum compound is selected from methylaluminoxane (MAO), ethylaluminoxane (EAO), isobutylaluminoxane (IBAO), modified methylaluminoxane (MMAO), or a combination thereof. Most preferably, the organoaluminum compound is selected from methylaluminoxane (MAO), ethylaluminoxane (EAO), or a combination thereof.
[0034] According to the present application, if the organoaluminum compound is a solution, it needs to be distilled to obtain a pure substance.
[0035] In a preferred embodiment, in the first dehydration treatment of step 1), the molar ratio of the amount of the organic aluminum compound to the amount of water contained in the toluene is 0.5-20:1, preferably 1-10:1, and more preferably 1-5:1, calculated as metallic Al.
[0036] In a preferred embodiment, the temperature of the first dehydration treatment in step 1) is controlled at 0-110°C, preferably 0-80°C, more preferably 0-50°C.
[0037] In a preferred embodiment, in the first dehydration treatment of step 1), the volume of the high-water-content toluene is at least 100 L, for example, 100 L, 150 L, 200 L, 250 L, 300 L, 400 L, 500 L, etc.
[0038] In a preferred embodiment, the bottom temperature of the distillation or rectification in step 2) is controlled at 110-200°C, preferably 110-170°C, more preferably 110-150°C.
[0039] In certain preferred embodiments, the distillation or rectification in step 2) is carried out under stirring conditions, and the stirring rate is controlled at 1-800 rpm, preferably 1-500 ppm, and more preferably 1-300 ppm.
[0040] In a preferred embodiment, in the second dehydration treatment of step 3), the molecular sieve used is selected from 3A, 4A, 5A, 10X, 13X, NaY molecular sieve, or a combination thereof, preferably selected from 3A, 4A, 5A, 13X molecular sieve, or a combination thereof, and most preferably selected from 3A, 4A molecular sieve, or a combination thereof. Further preferably, the amount of the molecular sieve added is controlled to be 2-30 g, preferably 5-20 g, and more preferably 10-20 g per 100 ml of toluene.
[0041] In a preferred embodiment, the time of the second dehydration treatment in step 3) is not less than 6 hours, preferably not less than 12 hours, such as 12 hours, 16 hours, 24 hours, 48 hours, etc. Further preferably, the time of the second dehydration treatment does not exceed 14 days.
[0042] Example
[0043] The present application is further described in detail below with reference to embodiments, but the present application is not limited to these embodiments.
[0044] In the following examples and comparative examples, the water content of toluene was measured using a water analyzer. Specifically, a Mettler Toledo C20 Karl Fischer titrator was used for measurement. During the measurement, the temperature of the weighing room should be kept between 10-30° C. and the relative air humidity should be kept between 45-60%. 1 ml of toluene was measured during the measurement.
[0045] Embodiment 1:
[0046] Take 500ml of toluene with a water content of 118.42ppm in a 1L distillation flask, add 0.5g of solid methylaluminoxane (MAO) obtained by vacuum distillation under nitrogen atmosphere at room temperature, and distill for 3h at 140℃ and 300rpm stirring. Transfer the distilled toluene to a 1L liquid storage bottle, then add 50g of 4A molecular sieve, soak for 12h, and after analysis, the water content of toluene is 15.75ppm.
[0047] Embodiment 2:
[0048] Take 500ml of toluene with a water content of 118.42ppm in a 1L distillation flask, add 0.5g of solid methylaluminoxane (MAO) obtained by vacuum distillation under nitrogen atmosphere at room temperature, and distill for 3h at 140℃ and 300rpm stirring. Transfer the distilled toluene to a 1L liquid storage bottle, then add 50g of 3A molecular sieve, soak for 12h, and after analysis, the water content of toluene is 13.67ppm.
[0049] Embodiment 3:
[0050] Take 500ml of toluene with a water content of 118.42ppm in a 1L distillation flask, add 1.0g of solid isobutylaluminoxane (IBAO) obtained by vacuum distillation under nitrogen atmosphere at room temperature, and distill for 3h at 140℃ and 300rpm stirring. Transfer the distilled toluene to a 1L liquid storage bottle, then add 70g of 4A molecular sieve, soak for 24h, and after analysis, the water content of toluene is 10.24ppm.
[0051] Embodiment 4:
[0052] Take 500ml of toluene with a water content of 118.42ppm in a 1L distillation flask, add 1.8ml of triisobutylaluminum (Al(i-C4H9)3) at room temperature under nitrogen atmosphere, and distill for 3h at 140℃ and 200rpm stirring. Transfer the distilled toluene to a 1L liquid storage bottle, then add 50g of 4A molecular sieve, soak for 24h, and after analysis, the water content of toluene is 13.26ppm.
[0053] Comparative Example 1:
[0054] Take 500ml of toluene with a water content of 118.42ppm in a 1L distillation flask, add 0.6g of calcium oxide under nitrogen atmosphere at room temperature, and distill for 3h at 140℃ and 300rpm stirring. Transfer the toluene obtained by distillation to a 1L liquid storage bottle, then add 50g of 4A molecular sieve, soak for 12h, and the water content of toluene is 37.64ppm after analysis; after soaking for 24h, the water content of toluene is 26.34ppm after analysis.
[0055] Comparative Example 2:
[0056] Take 500 ml of toluene with a water content of 118.42 ppm into a 1 L liquid storage bottle, then add 50 g of 4A molecular sieve, and soak for 24 hours. After analysis, the water content of toluene is 49.87 ppm.
[0057] By comparing the results of Examples 1-4 and Comparative Examples 1-2, it can be seen that under the same conditions, compared with commonly used chemical dehydrating agents and molecular sieves, the present invention uses an organoaluminum compound as a dehydrating agent, which can more effectively reduce the water content in toluene with high water content.
[0058] Embodiment 5:
[0059] 200L of toluene with a water content of 132.41ppm was placed in a distillation tower. Under the conditions of room temperature, nitrogen, and a pressure of 0.2bar, 1.3Kg of solid methylaluminoxane (MAO) obtained by vacuum distillation was added. The bottom oil temperature of the distillation tower was set to 150°C, and the reflux ratio was set to 1:1 for distillation. Then, 20Kg of 4A molecular sieve was added to the distillation toluene extraction tank. After soaking for 10 days, the water content of toluene was analyzed to be 12.06ppm.
[0060] Comparative Example 3:
[0061] 20Kg 4A molecular sieve was added to a 200L toluene storage tank with a water content of 132.41ppm. The water content was monitored at regular intervals. The results are shown in the following table:
[0062]
[0063] Embodiment 6:
[0064] 200L of toluene with a water content of 432.49ppm was placed in a distillation tower. Under the conditions of room temperature, nitrogen, and a pressure of 0.2bar, 3.3Kg of solid methylaluminoxane (MAO) obtained by vacuum distillation was added. The bottom oil temperature of the distillation tower was set to 150°C, and the reflux ratio was set to 1:1 for distillation. Then, 30Kg of 4A molecular sieve was added to the distillation toluene extraction tank. After soaking for 12 days, the water content of toluene was analyzed to be 18.39ppm.
[0065] By comparing the results of Examples 5-6 and Comparative Example 3, it can be seen that for large quantities of high-water-content toluene (water content can be as high as 400 ppm), the method of the present invention can still reduce its water content to below 20 ppm in a relatively short period of time; in contrast, the conventional molecular sieve soaking method cannot reduce the water content of large quantities of high-water-content toluene with a water content of more than 100 ppm to below 20 ppm in a relatively short period of time.
[0066] The preferred embodiments of the present invention have been specifically described above with reference to the embodiments, but these descriptions are only illustrative and not restrictive. Those skilled in the art may make various obvious changes and modifications to these preferred embodiments without departing from the spirit and scope of the present invention, and these changed or modified embodiments still fall within the protection scope of the present invention.
Claims
1. A method for dehydrating high-water-content toluene having a water content of at least 100 ppm, comprising the steps of: 1) Under an inert atmosphere, the high water content toluene is contacted with an organoaluminum compound having at least one R-A1 bond for a first dehydration treatment, wherein R represents an alkyl group, preferably C 1-8 Alkyl, more preferably C 1-6 alkyl; 2) performing distillation or rectification simultaneously with step 1) or after step 1) to obtain partially dehydrated toluene; and 3) contacting the partially dehydrated toluene with a molecular sieve for a second dehydration treatment to obtain dehydrated toluene, for example, dehydrated toluene with a water content of less than 20 ppm.
2. The method according to claim 1, wherein the organic aluminum compound has a boiling point higher than toluene and is selected from alkyl aluminum, alkyl aluminoxane, or a combination thereof.
3. The method according to claim 2, wherein the alkyl aluminum has a structure shown in general formula (I), Al(R1)3 (I) wherein each group R1 is independently selected from alkyl, alkoxy, halogen and amine, and at least one R1 group is an alkyl group, preferably C 1-8 Alkyl, more preferably C 1-6 Alkyl, particularly preferably C 1-4 alkyl.
4. The method according to claim 2 or 3, wherein the alkylaluminoxane has a structure shown in general formula (II), [-Al(R2)O-] n (II) Wherein each group R2 is independently selected from C 1-8 Alkyl, preferably C 1-6 Alkyl, more preferably C 1-4 Alkyl, n is a positive integer, preferably 1-50.
5. The method according to claim 1, wherein the organoaluminum compound is selected from methylaluminoxane (MAO), ethylaluminoxane (EAO), isobutylaluminoxane (IBAO), modified methylaluminoxane (MMAO), tri-n-hexylaluminum (Al( n C6H 13 )3) triisohexyl aluminum (Al( i C6H 13 )3) Tri-n-pentyl aluminum (Al( n C5H 11 )3) Triisopentyl aluminum (Al( i C5H 11 )3), diethylaluminum iodide (Al(CH3CH2)2I), diethylaluminum bromide (Al(CH3CH2)2Br), diethylaluminum chloride (Al(CH3CH2)2Cl), di-n-butylaluminum chloride (Al( n C4H9)2Cl), diisobutylaluminum chloride (Al( i C4H9)2Cl), diethyldiethylamine aluminum (Al(Et2N)Et2), N-ethyl-N-isopropylaminodimethylaluminum (Al( i PrNEt)(Me)2), or a combination thereof, Preferably selected from methylaluminoxane (MAO), ethylaluminoxane (EAO), isobutylaluminoxane (IBAO), modified methylaluminoxane (MMAO), or a combination thereof, More preferred is methylaluminoxane (MAO), ethylaluminoxane (EAO), or a combination thereof.
6. The method according to any one of claims 1 to 5, wherein in the first dehydration treatment of step 1), the molar ratio of the amount of the organoaluminum compound to the amount of water contained in the toluene is 0.5-20:1, preferably 1-10:1, more preferably 1-5:1, calculated as metallic Al. Preferably, the temperature of the first dehydration treatment in step 1) is controlled at 0-110°C, preferably 0-80°C, more preferably 0-50°C.
7. The method according to any one of claims 1 to 6, wherein in the first dehydration treatment of step 1), the volume of the high-water-content toluene is at least 100 L, such as 100-500 L.
8. The method according to any one of claims 1 to 7, wherein the bottom temperature of the distillation or rectification in step 2) is controlled at 110-200°C, preferably 110-170°C, more preferably 110-150°C.
9. The method according to any one of claims 1 to 8, wherein the distillation or rectification in step 2) is carried out under stirring conditions, and the stirring rate is controlled at 1-800 rpm, preferably 1-500 ppm, more preferably 1-300 ppm.
10. The method according to any one of claims 1 to 9, wherein in the second dehydration treatment of step 3), the molecular sieve used is selected from 3A, 4A, 5A, 10X, 13X, NaY molecular sieve, or a combination thereof, preferably selected from 3A, 4A, 5A, 13X molecular sieve, or a combination thereof, most preferably selected from 3A, 4A molecular sieve, or a combination thereof; Preferably, the amount of the molecular sieve added is controlled at 2-30 g, preferably 5-20 g, more preferably 10-20 g per 100 ml of toluene; More preferably, the time of the second dehydration treatment in step 3) is not less than 6 hours, preferably not less than 12 hours.