CN110668909B - Purification method of environment-friendly n-hexane - Google Patents
Purification method of environment-friendly n-hexane Download PDFInfo
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- CN110668909B CN110668909B CN201911009213.XA CN201911009213A CN110668909B CN 110668909 B CN110668909 B CN 110668909B CN 201911009213 A CN201911009213 A CN 201911009213A CN 110668909 B CN110668909 B CN 110668909B
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- C07C7/005—Processes comprising at least two steps in series
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- C—CHEMISTRY; METALLURGY
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- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/04—Purification; Separation; Use of additives by distillation
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- C07C7/148—Purification; Separation; Use of additives by treatment giving rise to a chemical modification of at least one compound
- C07C7/14858—Purification; Separation; Use of additives by treatment giving rise to a chemical modification of at least one compound with inorganic compounds not provided for before
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Abstract
The invention discloses a purification method of environment-friendly n-hexane, which is characterized by comprising the following steps: step 1, taking industrial-grade n-hexane, adding AR-grade sulfuric acid into the industrial-grade n-hexane, stirring and standing, and separating a lower-layer liquid; step 2, introducing the n-hexane obtained in the step 1 into an alkali column for circulating flow to process, and then separating out the n-hexane; and 3, rectifying the n-hexane separated in the step 2, and collecting the rectified n-hexane to obtain the environment-friendly n-hexane. By adopting a treatment mode of sulfuric acid and alkali columns, the environment-friendly n-hexane with the purity of more than 98% and the transmittance of 225nm ultraviolet rays of more than 90% is obtained, the influence of impurities such as metal ions on the optical performance of the n-hexane is effectively controlled, the parameter requirement of the environment-friendly n-hexane is met, and the problem that an enterprise cannot normally produce the environment-friendly n-hexane at present is solved.
Description
Technical Field
The invention relates to the technical field of n-hexane purification, and particularly relates to a purification method of environment-friendly n-hexane.
Background
The industrial grade n-hexane contains a small amount of impurities such as benzene, olefin, isomer and the like, the purity of the industrial grade n-hexane is only 78-86%, the requirements of the field of testing analysis such as an infrared oil tester cannot be met, the purity of the existing n-hexane prepared by a molecular sieve pressure swing adsorption method reaches 99%, but the preparation is complex, the cost is high, and the industrial grade n-hexane is not widely applied in industry. At present, the industrial-grade n-hexane purification method adopts a mode of rectifying or azeotropic distilling n-hexane for multiple times for purification, and the purity of the n-hexane can reach 97 percent.
However, the high-end requirement of special fields cannot be satisfied by industrial grade n-hexane with a purity of only 97%, for example, when the n-hexane is used for chromatograph and mass spectrometer analysis, the grade of the n-hexane required by the method reaches a chromatographic grade, namely, the purity reaches more than 98%, as disclosed in chinese patent CN 105085140B.
Chinese patent CN108017504A discloses a method for purifying n-hexane, which comprises the following steps: taking raw material n-hexane, fully contacting the raw material n-hexane with fuming sulfuric acid, neutralizing with an alkali solution, and finally washing with pure water; and rectifying the washed product to obtain n-hexane with purity over 99%. The purification method can meet the requirement of organic matter analyzers such as chromatographic mass spectrometry on the purity of the n-hexane, has simple and uncomplicated process and relatively low input cost, and is suitable for large-scale industrial production.
However, when the applicant tests the method, the method is not suitable for producing environment-friendly n-hexane, specifically, the purity of the environment-friendly n-hexane is required to be more than 98%, and the 225nm ultraviolet transmittance is not less than 90% (refer to the ultraviolet spectrophotometry for measuring water quality/petroleum types of HJ970-2018 issued by ministry of ecological environment), wherein the 225nm ultraviolet transmittance is a main characteristic of the environment-friendly n-hexane, and when the parameter is not in accordance with the parameter, the requirement of the environment-friendly n-hexane is not met, the purity of the n-hexane obtained according to the method disclosed by Chinese patent CN108017504A can reach more than 98%, the requirement can be met, and the 225nm ultraviolet transmittance can only reach 85%, the requirement of the environment-friendly n-hexane cannot be met, and the method is suitable for producing environment-friendly n-hexane for a long timeThe method is obtained after experimental summarization, and besides the factors of raw material sources and equipment types, the method has the defects that alkaline solution and pure water are introduced in the preparation process, the alkaline solution and the pure water cannot reach ideal states in actual production, and the alkaline solution and the pure water used in actual production contain different types of metal ions, such as K+、Ca2+、Na+、Mg2+、Fe3+After the n-hexane is washed and separated by pure water, a small amount of water is still contained, different types of metal ions are dissolved in the n-hexane, and in the subsequent rectification process, the metal ions are mixed into the n-hexane, although the metal ions are trace and have little influence on the purity of the n-hexane, the metal ions have great influence on the optical property of the n-hexane, so that the transmittance of the prepared n-hexane in 225nm ultraviolet rays can only reach 85%, the n-hexane cannot be used for producing environment-friendly n-hexane, the existing other production processes cannot meet the requirement of the environment-friendly n-hexane in purity, even if the n-hexane is produced by adopting a complex production process, an enterprise does not have profit space, and the enterprise cannot normally produce the environment-friendly n-hexane after the environment-friendly n-hexane is subjected to standard test.
Disclosure of Invention
The invention aims to: aiming at the existing problems, the method for purifying the environment-friendly n-hexane is provided, inherits the thought of not introducing impurities, effectively controls the introduction of impurities such as metal ions by adopting a treatment mode of sulfuric acid and an alkali column, reduces the content of the metal ions in the n-hexane under the condition of not increasing the production cost, and solves the problem that the current enterprises cannot normally produce the environment-friendly n-hexane.
The technical scheme adopted by the invention is as follows: the purification method of the environment-friendly n-hexane is characterized by comprising the following steps:
step 1, taking industrial-grade n-hexane, adding AR-grade sulfuric acid into the industrial-grade n-hexane, stirring and standing, and separating a lower-layer liquid;
step 2, introducing the n-hexane obtained in the step 1 into an alkali column for circulating flow to process, and then separating out the n-hexane;
and 3, rectifying the n-hexane separated in the step 2, and collecting the rectified n-hexane to obtain the environment-friendly n-hexane.
In the process, industrial grade n-hexane is treated by high-purity AR grade sulfuric acid (analytically pure grade sulfuric acid with the concentration of 95-98%), then is treated by an alkali column, and finally is distilled to obtain an environment-friendly grade n-hexane product. In the reprocessing process, high-purity sulfuric acid is adopted to avoid introducing new impurities and facilitate removal of impurities such as water, olefin and benzene in n-hexane, after the n-hexane is separated by sulfuric acid treatment, a small amount of sulfuric acid solution and other impurities which cannot be treated by sulfuric acid can be remained, and at the moment, alkaline substances are required to be used for continuous treatment. Compared with the alkaline solution mode adopted by the Chinese patent CN108017504A, firstly, impurities such as water and metal ions are not introduced, and then the contents of the metal ions and the water in the normal hexane can be effectively controlled, and a precondition is provided for obtaining the normal hexane meeting the requirement of environmental protection level, secondly, because the alkaline column is in a solid state, the normal hexane treated by the alkaline column does not need to be washed by pure water, thereby simplifying the working procedures, avoiding introducing the impurities into the normal hexane again, ensuring the purity of the normal hexane, effectively controlling the content of the metal ions, and further obtaining the normal hexane meeting the requirement of environmental protection level, in addition, the alkaline column of the invention can realize repeated use for many times because the normal hexane is treated by the absorption mode, the generation amount of waste and waste liquid is almost negligible, and the use cost is low, the adoption of the alkali solution can generate more alkali waste liquid, so that the production cost of enterprises is overhigh, and particularly the cost rise is obvious when the mass production is carried out, therefore, the technical effect of the alkali column adopted by the invention is obviously better than that of the alkali solution.
Further, the alkali column of the present invention is a traditional alkali column, such as sodium hydroxide, potassium hydroxide, rubidium hydroxide, francium hydroxide, etc., and the sodium hydroxide alkali column is preferably used in the present invention in consideration of the use effect and cost.
Furthermore, in order to more fully utilize the sulfuric acid and reduce unnecessary waste, the volume ratio of the AR-grade sulfuric acid to the industrial-grade n-hexane is (1-2): 100. Because a certain amount of other impurities are dissolved in the treated sulfuric acid, if the treated sulfuric acid is directly recycled, the treatment effect is poor and cannot meet the production requirement, the sulfuric acid can only be discarded, if more sulfuric acid is used for treating normal hexane, the waste is serious, if a small amount of sulfuric acid is used, the treatment effect cannot be achieved, the sulfuric acid is obtained through hundreds of tests, and when the volume ratio of the AR-grade sulfuric acid to the industrial-grade normal hexane is (1-2):100, the utilization rate of the sulfuric acid is highest, and the waste is minimum.
Further, when the normal hexane is treated according to the proportion, the inventor finds that the proportion is not the optimal proportion for treating the normal hexane to achieve the optimal effect, namely, the normal hexane can be treated more thoroughly, however, in the actual adjustment, if the dosage of the sulfuric acid is simply increased, due to equipment and solute content, the treatment effect of the sulfuric acid is not in proportion to the dosage, the treatment effect of the single sulfuric acid is not increased along with the increase of the dosage of the sulfuric acid, and in order to overcome the problem, in the step 1, the normal hexane is repeatedly treated by using AR-grade sulfuric acid for 2-4 times. The inventor treats industrial normal hexane by adopting a multiple sulfuric acid treatment mode, so that the treatment is more thorough, and by adopting a multiple treatment mode, although the treatment time cost is increased, for example, in the treatment process, the stirring time of single treatment is generally 1-3h, if the treatment is repeated for 2 times, the stirring time needs to take 2-6h, the normal hexane is treated more thoroughly, the multiple treatment mode avoids the influence of impurities dissolved in sulfuric acid, the limitation of equipment is broken through, the purity of the normal hexane is ensured under the condition of not wasting the sulfuric acid, and a foundation is provided for producing high-purity normal hexane.
Furthermore, in order to enable the alkali column to fully treat the n-hexane, the n-hexane is introduced into the alkali column to circularly flow for 1-3h and then is separated. In the alkali column treatment, although heat is generated by the neutralization reaction, the reaction heat is negligible in a flowing state because the content of the acid is extremely low, and there is no concern about the influence of the reaction heat on the production process.
Further, in order to better obtain the required product, introducing the n-hexane separated out in the step 2 into a distillation kettle for distillation, controlling the distillation temperature, and collecting the n-hexane at the temperature of 68-69 ℃. The product can of course also be obtained by rectification in a known rectification column.
In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that: compared with the prior art, the purification method disclosed by the invention inherits the idea of avoiding introducing impurities into the n-hexane as much as possible, obtains the environment-friendly n-hexane with the purity of more than 98% and the transmittance of 225nm ultraviolet rays of more than 90% by adopting a treatment mode of sulfuric acid and an alkali column, effectively controls the influence of impurities such as metal ions on the optical performance of the n-hexane, meets the parameter requirements of the environment-friendly n-hexane, and solves the problem that an enterprise cannot normally produce the environment-friendly n-hexane at present.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
The purification method of the environment-friendly n-hexane comprises the following steps:
step 1, adding AR-grade sulfuric acid and industrial-grade n-hexane into a processing barrel with the volume ratio of 1.5:100, stirring for 2 hours, standing for layering, wherein the lower layer is a sulfuric acid solution, and then separating the lower layer of the sulfuric acid solution;
step 2, repeating the operation of the step 1 for 2 times to obtain n-hexane repeatedly treated by sulfuric acid, introducing the n-hexane into a sodium hydroxide alkali column for circulating flow for 2 hours, and then separating the n-hexane;
and 3, introducing the normal hexane separated in the step 2 into a distillation kettle with the capacity of 500L for distillation, collecting the normal hexane in the kettle at the temperature of between 68 and 69 ℃ at the temperature of 78 ℃, and bottling and filling nitrogen for storage after the normal hexane is detected to be qualified.
Example 2
The purification method of the environment-friendly n-hexane comprises the following steps:
step 1, adding AR-grade sulfuric acid and industrial-grade n-hexane into a processing barrel with the volume ratio of 1:100, stirring for 1 hour, standing for layering, wherein the lower layer is a sulfuric acid solution, and then separating the lower layer of the sulfuric acid solution;
step 2, repeating the operation of the step 1 for 4 times to obtain n-hexane repeatedly treated by sulfuric acid, introducing the n-hexane into a sodium hydroxide alkali column for circulating flow for 1h, and then separating the n-hexane;
and 3, introducing the normal hexane separated in the step 2 into a distillation kettle with the capacity of 500L for distillation, collecting the normal hexane in the kettle at the temperature of between 68 and 69 ℃ at the temperature of 78 ℃, and bottling and filling nitrogen for storage after the normal hexane is detected to be qualified.
Example 3
The purification method of the environment-friendly n-hexane comprises the following steps:
step 1, adding AR-grade sulfuric acid and industrial-grade n-hexane into a processing barrel with the volume ratio of 2:100, stirring for 3 hours, standing for layering, wherein the lower layer is a sulfuric acid solution, and then separating the lower layer of the sulfuric acid solution;
step 2, repeating the operation of the step 1 for 2 times to obtain n-hexane repeatedly treated by sulfuric acid, introducing the n-hexane into a sodium hydroxide alkali column for circulating flow for 3 hours, and then separating the n-hexane;
and 3, introducing the normal hexane separated in the step 2 into a distillation kettle with the capacity of 500L for distillation, collecting the normal hexane in the kettle at the temperature of between 68 and 69 ℃ at the temperature of 78 ℃, and bottling and filling nitrogen for storage after the normal hexane is detected to be qualified.
Example 4
The purification method of the environment-friendly n-hexane comprises the following steps:
step 1, adding AR-grade sulfuric acid and industrial-grade n-hexane into a processing barrel with the volume ratio of 1.5:100, stirring for 1 hour, standing for layering, wherein the lower layer is a sulfuric acid solution, and separating the lower layer of the sulfuric acid solution;
step 2, repeating the operation of the step 1 for 3 times to obtain n-hexane repeatedly treated by sulfuric acid, introducing the n-hexane into a sodium hydroxide alkali column for circulating flow for 1h, and then separating the n-hexane;
and 3, introducing the normal hexane separated in the step 2 into a distillation kettle with the capacity of 500L for distillation, collecting the normal hexane in the kettle at the temperature of between 68 and 69 ℃ at the temperature of 78 ℃, and bottling and filling nitrogen for storage after the normal hexane is detected to be qualified.
Example 5
The purification method of the environment-friendly n-hexane comprises the following steps:
step 1, adding AR-grade sulfuric acid and industrial-grade n-hexane into a processing barrel with the volume ratio of 1.5:100, stirring for 2 hours, standing for layering, wherein the lower layer is a sulfuric acid solution, and then separating the lower layer of the sulfuric acid solution;
step 2, repeating the operation of the step 1 for 2 times to obtain n-hexane repeatedly treated by sulfuric acid, introducing the n-hexane into a sodium hydroxide alkali column for circulating flow for 2 hours, and then separating the n-hexane;
and 3, introducing the normal hexane separated in the step 2 into a distillation kettle with the capacity of 500L for distillation, collecting the normal hexane in the kettle at the temperature of between 68 and 69 ℃ at the temperature of 78 ℃, and bottling and filling nitrogen for storage after the normal hexane is detected to be qualified.
The test data for the products obtained in examples 1 to 5 above are shown in the following table:
TABLE 1 raw assay data for samples run Nos. 1-5 (examples 1-5)
As can be seen from the table above, the purity of the environment-friendly n-hexane obtained by the purification method is more than 98%, the transmittance of 225nm ultraviolet rays is more than 90%, the requirement of national standards on the environment-friendly n-hexane is met, and the purification method can be used for producing the environment-friendly n-hexane and overcomes the defects in the prior art. The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (2)
1. The purification method of the environment-friendly n-hexane is characterized by comprising the following steps:
step 1, taking industrial-grade n-hexane, adding AR-grade sulfuric acid into the industrial-grade n-hexane, wherein the volume ratio of the AR-grade sulfuric acid to the industrial-grade n-hexane is (1-2):100, stirring for 1-3h, standing, separating out lower-layer liquid, and repeatedly treating the n-hexane with the AR-grade sulfuric acid for 2-4 times;
step 2, introducing the normal hexane obtained in the step 1 into a sodium hydroxide alkali column for circulating flow for treatment, and separating the normal hexane after the normal hexane is introduced into the sodium hydroxide alkali column for circulating flow for 1-3 h;
and 3, rectifying the n-hexane separated in the step 2, and collecting the rectified n-hexane to obtain the environment-friendly n-hexane.
2. The method for purifying environmental grade n-hexane as claimed in claim 1, wherein in the step 3, the n-hexane separated in the step 2 is introduced into a distillation still for distillation, the distillation temperature is controlled, and the n-hexane at 68-69 ℃ is collected.
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| SU910566A1 (en) * | 1980-04-22 | 1982-03-07 | Харьковский Ордена Ленина Политехнический Институт Им. В.И.Ленина | Process for purifying hexane from formic acid esters |
| CN105085149A (en) * | 2014-05-16 | 2015-11-25 | 上海星可高纯溶剂有限公司 | Purification method of high-purity organic solvent cyclohexane |
| CN106565401A (en) * | 2016-11-01 | 2017-04-19 | 辽宁石油化工大学 | Purification method of petroleum ether |
| CN106854130A (en) * | 2015-12-09 | 2017-06-16 | 天津市科密欧化学试剂有限公司 | A kind of preparation method of chromatographic grade n-hexane |
| CN107652155A (en) * | 2017-10-25 | 2018-02-02 | 广东工业大学 | A kind of method for producing the residual level n-hexane of agriculture |
| CN108017504A (en) * | 2018-01-26 | 2018-05-11 | 上海星可高纯溶剂有限公司 | The method of purification of n-hexane |
| CN109160870A (en) * | 2018-09-14 | 2019-01-08 | 成都市科隆化学品有限公司 | A kind of production method of chromatograph-grade normal heptane |
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Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU910566A1 (en) * | 1980-04-22 | 1982-03-07 | Харьковский Ордена Ленина Политехнический Институт Им. В.И.Ленина | Process for purifying hexane from formic acid esters |
| CN105085149A (en) * | 2014-05-16 | 2015-11-25 | 上海星可高纯溶剂有限公司 | Purification method of high-purity organic solvent cyclohexane |
| CN106854130A (en) * | 2015-12-09 | 2017-06-16 | 天津市科密欧化学试剂有限公司 | A kind of preparation method of chromatographic grade n-hexane |
| CN106565401A (en) * | 2016-11-01 | 2017-04-19 | 辽宁石油化工大学 | Purification method of petroleum ether |
| CN107652155A (en) * | 2017-10-25 | 2018-02-02 | 广东工业大学 | A kind of method for producing the residual level n-hexane of agriculture |
| CN108017504A (en) * | 2018-01-26 | 2018-05-11 | 上海星可高纯溶剂有限公司 | The method of purification of n-hexane |
| CN109160870A (en) * | 2018-09-14 | 2019-01-08 | 成都市科隆化学品有限公司 | A kind of production method of chromatograph-grade normal heptane |
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