CN1328994A - High-purity acetonitrile refining method - Google Patents
High-purity acetonitrile refining method Download PDFInfo
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- CN1328994A CN1328994A CN 00116536 CN00116536A CN1328994A CN 1328994 A CN1328994 A CN 1328994A CN 00116536 CN00116536 CN 00116536 CN 00116536 A CN00116536 A CN 00116536A CN 1328994 A CN1328994 A CN 1328994A
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Abstract
The present invention relates to a refining method for obtaining hihg-purity acetonitrile, and is mainly aimed at solving the problems of high oxazole content in acetonitrile product, influence of oxazole content on quality of acetonitrile product or larger loss of acetonitrile resulted from separation of oxazole which are existed in the previous technology. This invention is characterized by that in the traditional combined technological process including removing hydrocyanic acid in reaction tower, chemial treatment, reduced pressure and pressure azeotropic distillation, it adopts the technical scheme of extracting side stream liquid phase oxazole from upper portion of rectifying section of hydrocyanic acid removing tower so as to better solve the above-mentioned problems. It can obtain high-purity acetonitrile, and the loss of acetonitrile is less. This invention can be used in separation equipment of industrial acetonitrile.
Description
The present invention relates to a kind of high-purity acetonitrile refining method.
In the production process of ammoxidating propylene to prepare acrylonitrile, while coproduct hydrogen cyanic acid and acetonitrile, wherein impurity such as aldehyde, Tong, oxazole, propionitrile and a spot of prussic acid are extracted to acetonitrile solution in vinyl cyanide extraction desorption process, through acetonitrile desorb or stripping in crude acetonitrile.Usually we adopt by the combination process that takes off nitrile tower, chemical treatment, decompression, pressurization component distillation, acetonitrile is reclaimed continuously, can remove impurity such as water and propenal in the acetonitrile, propionitrile, acetone, vinylcarbinol effectively, but Za Zhi oxazole since can be in system circulative accumulation, finally can influence the quality product of acetonitrile.Document US 4,308,108 have reported a kind of technology of the crude acetonitrile of purifying, and adopt the method for water extraction Tuo Chu oxazole, from the mixture of the top Tuo Chu oxazole of extractive distillation column and water, acetonitrile, obtain acetonitrile from the bottom of extractive distillation column.Caused the greater loss of acetonitrile with this method Tuo Chu oxazole.Document US 5,426,208 have reported the technology of another kind of purification acetonitrile, removed impurity such as the processing Shi oxazole formation oxide compound of the acetonitrile of moisture content, removed oxide compound and excessive ozone through a tower of having filled molecular sieve again, thereby obtain acetonitrile of high purity through ozone.The acetonitrile purity that obtains with this method is very high, can meet the service requirements of UV spectrophotometer, electrolytic analysis research, DNA chemistry and high speed liquid chromatography instrument.But must increase by two steps of ozonize and molecular sieve adsorption again on the basis of removing moisture content and most of impurity, product cost is higher.
Document EP 55920 has been reported a kind of technology of continuous recovery acetonitrile.This technology may further comprise the steps: a) crude acetonitrile separates through first knockout tower, and HCN and light component are discharged by cat head, and portion water and heavy component are discharged by the tower still; B) water-acetonitrile that contains that has removed light component is extracted out after the chemical treatment still adds alkali and the formal chemistry is handled from the first knockout tower stripping section bottom side line gas phase; C) after chemical treatment removes HCN, contain second knockout tower that water-acetonitrile enters decompression, remove heavy component at the tower still; D) steam the 3rd knockout tower that the acetonitrile that has removed most of water enters pressurization from the second knockout tower cat head, cat head steams the acetonitrile material that contains light organic component and moisture content and returns the first knockout tower charging, stripping section bottom gas phase extract out the finished product acetonitrile.This technology has removed most of impurity more effectively, obtains the acetonitrile product of higher degree, but this technology is not considered removing of Za Zhi oxazole, can not Xiao Chu oxazole to the influence of quality product.The existence of You Yu oxazole, acetonitrile will influence the quality of postorder product in industrial application, and will be difficult in the general rectifying and removes.
The objective of the invention is to have acetonitrile Chan Pin Zhong oxazole content height in the previous patent technology, influence the acetonitrile quality product or, provide a kind of new high-purity acetonitrile refining method for Fen Li oxazole need cause the shortcoming of acetonitrile greater loss in order to overcome.This method has when obtaining acetonitrile of high purity, the characteristics that the acetonitrile loss is little.
The objective of the invention is to realize by following technical scheme: a kind of high-purity acetonitrile refining method, from contain acetonitrile, water, HCN, oxazole and heavy organic crude acetonitrile, reclaim high-purity acetonitrile continuously, may further comprise the steps successively:
A) crude acetonitrile separates through first knockout tower, and HCN and light component are discharged by cat head, and portion water and heavy organism are discharged by the tower still, take out out oxazole in the first knockout tower rectifying section top side line liquid phase;
B) having removed light component divides the water-acetonitrile that contains of oxazole to extract out after the chemical treatment still adds alkalization processing from the first knockout tower stripping section bottom side line gas phase with exhausted big portion;
C) learn to handle second knockout tower that water-acetonitrile enters decompression that contains after removing free HCN through adding alkalization, remove heavy organism and water at the tower still;
D) separate cat head from second and steam the 3rd knockout tower that the acetonitrile that has removed most of water enters pressurization, cat head steams the acetonitrile material that contains oxazole and moisture content and returns the first knockout tower charging, stripping section bottom gas phase extract out high-purity acetonitrile.
In the technique scheme, the first knockout tower tower top pressure is 0.1～0.13MPa, feeding temperature is 30～80 ℃, the cat head drop temperature is 29～45 ℃, it is 40～95 ℃ that the rectifying section side line is extracted temperature out, preferable range is 50～90 ℃, and it is 76～100 ℃ that the stripping section side line is extracted temperature out, and tower still temperature is 105～120 ℃; The second knockout tower tower top pressure is 100～250 mmhg, and feeding temperature is 30～50 ℃, and tower top temperature is 30～50 ℃, and tower still temperature is 55～75 ℃; The 3rd knockout tower tower top pressure is 0.1～0.4MPa, and feeding temperature is 30～85 ℃, and tower top temperature is 75～115 ℃, and it is 85～130 ℃ that the stripping section side line is extracted temperature out, and tower still temperature is 85～130 ℃; The position of the first knockout tower rectifying section side line liquid phase Chou Chu oxazole is from top to bottom 10～50% of a rectifying section height; The used alkali of chemical treatment is sodium hydroxide in the chemical treatment still.
Among the present invention, extract mouth out owing to increased a liquid phase on the rectifying section top of the first traditional knockout tower (removing the prussic acid tower), make Lei Ji De oxazole and prussic acid, water and minor amounts of acetonitrile be excluded system smoothly as light component, thereby guaranteed that the later separation tower can obtain highly purified acetonitrile product, during simultaneously owing to Chou Chu oxazole, only taken minor amounts of acetonitrile out of and discharged system, so the acetonitrile loss is less, has obtained effect preferably as light component.
Fig. 1 is high-purity acetonitrile refining technical process of the present invention.
1 for dehydrogenation cyanic acid tower among Fig. 1, and 2 be vacuum still, and 3 are the pressure distillation tower, and 4 is the chemical treatment still, and 5 is the raw material crude acetonitrile, and 6 is the finished product acetonitrile, and 7 take out out oxazole for rectifying section top side line liquid phase.
The raw material crude acetonitrile enters from tower 1 (dehydrogenation cyanic acid tower) middle part, is got rid of the light components such as its hydrogen cyanide by cat head, and tower reactor is got rid of Part water and heavy component, the water-acetonitrile that contains that has removed light component removes the chemical treatment still from tower 1 stripping section bottom side line gas phase extraction Add alkali (NaOH) and carry out chemical treatment. Through chemical treatment remove free hydrogen cyanic acid contain water-acetonitrile through tower 2 (vacuum distillation tower), After the decompression of tower 3 (distillation under pressure tower), the pressurization combination dehydration, get rid of heavy component impurity from tower 2 tower reactors, remove most of water The acetonitrile of part distillates tower 3 ， Han oxazoles and water from tower 2 tops acetonitrile material returns tower 1 by tower 3 tops, by tower 1 essence The section of heating up in a steamer top side line liquid phase is taken out out oxazole, to guarantee obtaining high-purity finished product acetonitrile from the stripping section bottom of tower 3.
The invention will be further elaborated below by embodiment: [comparative example 1]
Contain of the middle part adding of the raw material crude acetonitrile (concentration is 50%) of acetonitrile 50%, vinylcarbinol trace, propionitrile 5000PPm, oxazole trace from tower 1 (removing the prussic acid tower), working pressure is a normal pressure, the cat head drop temperature is 35 ℃, and tower still temperature is 115 ℃, and it is 92 ℃ that the stripping section side line is extracted temperature out.It is that 70% acetonitrile goes chemical treatment that removed overhead prussic acid, stripping section side line are extracted concentration out, enters tower 2 (vacuum still), tower 3 (pressure distillation tower) after the chemical treatment, and tower 2 working pressures are 200 mmhg, and tower 3 working pressures are 0.3MPa.Get rid of impurity such as water and heavy organism from tower 2 tower stills, obtain the finished product acetonitrile from tower 3 side lines.Crude acetonitrile is refining through above flow process, and finished product acetonitrile Zhong De oxazole is 1500PPm.[embodiment 1]
On the basis of comparative example 1, increase liquid phase at 10% place (from top to bottom) of the total rectifying section stage number in the rectifying section top of tower 1 and extract mouth out, extract the acetonitrile material of a small amount of Han oxazole out, Qi Zhong Han oxazole 10%, water 15.5%, 1.3% light component, other is acetonitrile, the extraction amount is 0.01% of an inlet amount, and extracting temperature out is 80 ℃.Other operational condition is constant.Behind rectifying section side line liquid phase Chou Chu oxazole, the concentration of extracting out from the stripping section side line is about 70% acetonitrile makes with extra care through subsequent chemistry processings, tower 2, tower 3 dehydrations again, the moisture 310PPm, of the finished product acetonitrile oxazole trace that obtains from the stripping section side line of tower 3.[embodiment 2]
On the basis of comparative example 1, increase liquid phase at 50% place (from top to bottom) of the total rectifying section stage number in the rectifying section top of tower 1 and extract mouth out, extract the acetonitrile material of a small amount of Han oxazole out, Qi Zhong Han oxazole 4.5%, water 17.5%, 0.5% light component, other is acetonitrile, the extraction amount is 0.017% of an inlet amount, and extracting temperature out is 84 ℃.Other operational condition is constant.Behind rectifying section side line liquid phase Chou Chu oxazole, the concentration of extracting out from the stripping section side line is about 70% acetonitrile makes with extra care through subsequent chemistry processings, tower 2, tower 3 dehydrations again, the moisture 280PPm, of the finished product acetonitrile oxazole trace that obtains from the stripping section side line of tower 3.
Claims (6)
1, a kind of high-purity acetonitrile refining method reclaims high-purity acetonitrile continuously from contain acetonitrile, water, HCN, oxazole and heavy organic crude acetonitrile, may further comprise the steps successively:
A) crude acetonitrile separates through first knockout tower, and HCN and light component are discharged by cat head, and portion water and heavy organism are discharged by the tower still, take out out oxazole in the first knockout tower rectifying section top side line liquid phase;
B) having removed light component divides the water-acetonitrile that contains of oxazole to extract out after the chemical treatment still adds alkalization processing from the first knockout tower stripping section bottom side line gas phase with exhausted big portion;
C) learn to handle second knockout tower that water-acetonitrile enters decompression that contains after removing free HCN through adding alkalization, remove heavy organism and water at the tower still;
D) separate cat head from second and steam the 3rd knockout tower that the acetonitrile that has removed most of water enters pressurization, cat head steams the acetonitrile material that contains oxazole and moisture content and returns the first knockout tower charging, stripping section bottom gas phase extract out high-purity acetonitrile.
2, according to the described high-purity acetonitrile refining method of claim 1, it is characterized in that the first knockout tower tower top pressure is 0.1～0.13MPa, feeding temperature is 30～80 ℃, the cat head drop temperature is 29～45 ℃, it is 40～95 ℃ that the rectifying section side line is extracted temperature out, it is 76～100 ℃ that the stripping section side line is extracted temperature out, and tower still temperature is 105～120 ℃.
3, according to the described high-purity acetonitrile refining method of claim 1, it is characterized in that the second knockout tower tower top pressure is 100～250 mmhg, feeding temperature is 30～50 ℃, and tower top temperature is 30～50 ℃, and tower still temperature is 55～75 ℃.
4, according to the described high-purity acetonitrile refining method of claim 1, it is characterized in that the 3rd knockout tower tower top pressure is 0.1～0.4MPa, feeding temperature is 30～85 ℃, and tower top temperature is 75～115 ℃, it is 85～130 ℃ that the stripping section side line is extracted temperature out, and tower still temperature is 85～130 ℃.
5, according to the described high-purity acetonitrile refining method of claim 1, the position that it is characterized in that the first knockout tower rectifying section side line liquid phase Chou Chu oxazole is a rectifying section height from top to bottom 10～50%.
6,, it is characterized in that it is 50～90 ℃ that the rectifying section side line is extracted temperature out according to the described high-purity acetonitrile refining method of claim 2.
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| CN 00116536 CN1112351C (en) | 2000-06-15 | 2000-06-15 | High-purity acetonitrile refining method |
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| CN 00116536 CN1112351C (en) | 2000-06-15 | 2000-06-15 | High-purity acetonitrile refining method |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102633679A (en) * | 2012-04-01 | 2012-08-15 | 中国天辰工程有限公司 | Continuous purification method for crude acetonitrile |
| CN101570497B (en) * | 2009-06-15 | 2012-10-24 | 天津市康科德科技有限公司 | Method for purifying high-purity organic solvent acetonitrile for research |
| CN105985261A (en) * | 2015-01-31 | 2016-10-05 | 中国石油化工股份有限公司 | Acetonitrile refining method |
| CN114773228A (en) * | 2022-04-29 | 2022-07-22 | 河南新邦化工技术有限公司 | Method for refining acetonitrile by rectification-melt crystallization coupling process |
-
2000
- 2000-06-15 CN CN 00116536 patent/CN1112351C/en not_active Expired - Lifetime
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101570497B (en) * | 2009-06-15 | 2012-10-24 | 天津市康科德科技有限公司 | Method for purifying high-purity organic solvent acetonitrile for research |
| CN102633679A (en) * | 2012-04-01 | 2012-08-15 | 中国天辰工程有限公司 | Continuous purification method for crude acetonitrile |
| CN102633679B (en) * | 2012-04-01 | 2015-04-15 | 中国天辰工程有限公司 | Continuous purification method for crude acetonitrile |
| CN105985261A (en) * | 2015-01-31 | 2016-10-05 | 中国石油化工股份有限公司 | Acetonitrile refining method |
| CN114773228A (en) * | 2022-04-29 | 2022-07-22 | 河南新邦化工技术有限公司 | Method for refining acetonitrile by rectification-melt crystallization coupling process |
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| CN1112351C (en) | 2003-06-25 |
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