The purification process of beta-methylnaphthalene
Technical field
The present invention relates to the purification process of beta-methylnaphthalene, more specifically relate to from beta-methylnaphthalene, remove the method for impurity such as alpha-methyl-naphthalene, 2-methyl benzo-thiophene, 5-methyl benzo-thiophene.
Background technology
Beta-methylnaphthalene can be used for producing textile auxiliary agent, lubricant and plant-growth regulator, and the highly purified beta-methylnaphthalene more than 99% is the raw material of synthesise vitamins K class medicine and fodder additives.Extracting beta-methylnaphthalene from coal tar is the production method of a kind of beta-methylnaphthalene of industrial extensive employing.The purity of the beta-methylnaphthalene that utilizes ordinary method to purify from coal tar to obtain can reach more than 95%, generally contains impurity such as indoles, alpha-methyl-naphthalene, 2-methyl benzo-thiophene, 5-methyl benzo-thiophene.Chinese patent ZL00115067.7 provides a kind of method of removing indole from beta-methyl naphthalene, the purity that this method obtains purifying from coal tar by means such as pickling, alkali cleaning, distillations reaches 95% Beta-methyl naphtalene oil and removes indoles impurity and handle, and makes the purity of beta-methylnaphthalene bring up to more than 97%.Have not yet to see the relevant report that removes impurity such as alpha-methyl-naphthalene in the beta-methylnaphthalene, 2-methyl benzo-thiophene and 5-methyl benzo-thiophene.Do not see relevant from coal tar, the extraction yet and obtain the report that purity reaches the beta-methylnaphthalene more than 99%.
Summary of the invention
The purification process that the purpose of this invention is to provide a kind of simple to operate, beta-methylnaphthalene that cost is low, respond well.Thereby reduce the alpha-methyl-naphthalene in the beta-methylnaphthalene that extraction obtains from coal tar and the content of methyl benzo-thiophene impurity effectively, obtain the high-purity beta-methylnaphthalene more than 99%.
The handled beta-methylnaphthalene of the inventive method refers to remove resulting beta-methylnaphthalene product after the indoles impurity purification process according to the Beta-methyl naphtalene oil that Chinese patent ZL00115067.7 method obtains purifying from coal tar.The purity of this product is more than 97%, mainly contains impurity such as alpha-methyl-naphthalene, 2-methyl benzo-thiophene, 5-methyl benzo-thiophene.
The characteristics of the inventive method are to adopt solution crystal process that beta-methylnaphthalene is purified, and remove impurity such as alpha-methyl-naphthalene, 2-methyl benzo-thiophene, 5-methyl benzo-thiophene.Because the major impurity that the handled beta-methylnaphthalene raw material of the inventive method is contained is alpha-methyl-naphthalene, 2-methyl benzo-thiophene and 5-methyl benzo-thiophene, the content of alpha-methyl-naphthalene is lower in the raw material, even utilize the difference of alpha-methyl-naphthalene and beta-methylnaphthalene fusing point, separate also by freezing and crystallizing and to be difficult to alpha-methyl-naphthalene is eliminated, and the fusing point of 2-methyl benzo-thiophene is higher than the fusing point of beta-methylnaphthalene, the fusing point and the beta-methylnaphthalene fusing point of 5-methyl benzo-thiophene are approaching, therefore are difficult to separate to remove these impurity with freeze crystallization.Given this, and consider that the content of these impurity in raw material is lower, the present invention adopts solution crystal process that beta-methylnaphthalene is purified, to realize beta-methylnaphthalene and these separate impurities.According to the inventive method, behind alcoholic solvent dissolving beta-methylnaphthalene raw material, under agitation condition, carry out crystallization according to the temperature lowering curve of the linear distribution of setting, collect purified beta-methylnaphthalene after reaching the crystallization terminal temperature.
The inventive method may further comprise the steps:
(1) add beta-methylnaphthalene raw material and alcoholic solvent in crystallizer, by weight, the amount ratio of raw material and alcoholic solvent is 1: 0.5~3;
(2),, be cooled to crystallization 0~5 ℃ of temperature eventually while stirring with the constant speed of cooling of 0.01~15K/hr being not less than under 20 ℃ the starting temperature;
(3) the beta-methylnaphthalene crystallization is separated with impure mother liquor, obtain the beta-methylnaphthalene of purifying.
Solution crystallization can carry out also can carrying out off and on continuously in the inventive method, and used equipment all should have good hot-swap feature, preferably has the equipment of heating and cooling circulatory function simultaneously.Crystallizer can be selected stirred type crystallizer for use, as has the discontinuous crystallizer of anchor stirrer.
Alcoholic solvent particular methanol, ethanol, propyl alcohol, butanols, Virahol or their mixture, the effect that the wherein independent effect of using is better than mixing use.By weight, raw material is 1: 1~2 with the preferable amount ratio of alcoholic solvent.
Stirring velocity in the step (2) is 50~250rpm, and best stirring velocity is 100~200rpm; The refrigerative starting temperature depends on the concentration of crystallization solution, preferred 20~30 ℃ of starting temperature; Preferred speed of cooling is 0.5~10K/hr.
Can the beta-methylnaphthalene crystallization be separated with impure mother liquor by ordinary method, for example can adopt extrude, filtration or mode such as centrifugal realize in the beta-methylnaphthalene crystallization and the separating of impure mother liquor.
A preferred embodiment of the present invention is in the step (2), when beginning crystallization to occur, add nucleator, said nucleator adopts the beta-methylnaphthalene of purifying to be crystallized, its consumption is 0.005~2.5% of a beta-methylnaphthalene raw material weight, 0.01~0.5% of wherein preferred beta-methylnaphthalene raw material weight.
Another preferred embodiment of the present invention is step (3) to be separated the beta-methylnaphthalene crystallization that obtains wash, and to remove residual adhesion impurity, can further improve beta-methylnaphthalene crystalline purity by carrying out washing treatment.The alcohol solution of alcoholic solvent that washings employing crystallization is used or saturated beta-methylnaphthalene, the wherein alcohol solution of preferred saturated beta-methylnaphthalene.The use temperature of washings is 0~20 ℃, and preferred 0~5 ℃, temperature is identical eventually with crystallization for most preferred washings use temperature.The consumption of washings is 3~150% of a beta-methylnaphthalene raw material weight, 10~80% of wherein preferred beta-methylnaphthalene raw material weight.Mode of washing can be single wash or washing several times, and wherein preferably repeatedly washing for example, with 20% washing beta-methylnaphthalene crystallization of the total consumption of washings, is used remaining 80% repeated washing once earlier then.
In order to improve the yield of beta-methylnaphthalene, another preferred implementation of the present invention is that recycling step (3) separates the mother liquor that obtains, and adds in the crystallizer repeating step (2) and step (3) operation.Preferred mode is that recycling step (3) separates the residual washings of mother liquor and washing back that obtains, and merges this two kinds of solution, repeating step (2) and step (3) operation.
Beneficial effect
1, the inventive method can reduce effectively by coal tar and purifies and remove the content of handling impurity such as alpha-methyl-naphthalene, 2-methyl benzo-thiophene, 5-methyl benzo-thiophene in the beta-methylnaphthalene that obtains through indoles, obtain purity and be the high-purity beta-methylnaphthalene product more than 99%, can be widely used in textile auxiliary agent, lubricant, plant-growth regulator, production fields such as vitamin K class medicine and fodder additives, the application of having expanded the beta-methylnaphthalene product of from coal tar, purifying.
2, the inventive method has that operating procedure is simple, cost is low, low power consumption and other advantages.
Embodiment
Below by embodiment the inventive method is further elaborated, but does not limit the present invention:
Employed crystallizer is the stirred type crystallizer that has anchor stirrer (German JULABO company produce model F32-HP) among the following embodiment, and this crystallizer is provided with the refrigeration heating controller.
The beta-methylnaphthalene of the purified processing of following embodiment removes resulting beta-methylnaphthalene product after the indoles impurity purification process for the Beta-methyl naphtalene oil obtain purifying according to Chinese patent ZL00115067.7 method from coal tar, through gas chromatography determination, purity is 97.45wt%, and 2-methyl benzo-thiophene foreign matter content is that 0.64wt%, alpha-methyl-naphthalene foreign matter content are that 1.27wt%, 5-methyl benzo-thiophene foreign matter content are 0.1wt%.
Vapor-phase chromatography is adopted in the analysis of beta-methylnaphthalene product, uses GC-17A type gas chromatograph (day island proper Tianjin company).Chromatographic column is PEG20000 capillary column (φ 0.53mm * 30m * 0.5 μ m); Flame ionization ditector, detector temperature are 250 ℃; Column temperature is set 60 ℃ of initial temperature, rises to 230 ℃ with 4 ℃/min, keeps 15min; Carrier gas is a nitrogen, flow velocity 6mL/min; Sample size is 1 μ L; Adopt the area normalization method of band correction factor to calculate mensuration.
Embodiment 1
Take by weighing 30g beta-methylnaphthalene, 15g dehydrated alcohol, add and have in the stirred type crystallizer of anchor stirrer, elevated temperature to 30 ℃, under 100rpm speed stirs, constant speed of cooling with 0.5K/h is cooled to warm 5 ℃ eventually of crystallizations, filtration obtains the beta-methylnaphthalene crystallization, is 20 ℃ absolute ethanol washing subsequently with the 15g temperature, obtains the 10.5g crystallization.By analysis: the purity of beta-methylnaphthalene is that 99.07wt%, 2-methyl benzo-thiophene content are that 0.32wt%, alpha-methyl-naphthalene foreign matter content are that 0.47wt%, 5-methyl benzo-thiophene foreign matter content are 0.14wt%.
Embodiment 2
Take by weighing 30g beta-methylnaphthalene, 90g dehydrated alcohol, add and have in the stirred type crystallizer of anchor stirrer, elevated temperature to 20 ℃, under 80rpm speed stirs, constant speed of cooling cooling with 10K/h, when crystallization begins, add thick beta-methylnaphthalene raw material 0.3g, be cooled to warm 0 ℃ eventually of crystallization, filter and obtain the crystallization of 8.4g beta-methylnaphthalene.By analysis: the purity of beta-methylnaphthalene is that 99.46wt%, 2-methyl benzo-thiophene content are that 0.30wt%, alpha-methyl-naphthalene foreign matter content are that 0.14wt%, 5-methyl benzo-thiophene foreign matter content are 0.10wt%.Take by weighing 30g beta-methylnaphthalene and 30g filtrate, add and have in the stirred type crystallizer of anchor stirrer, carry out crystallization by embodiment 1 described operational condition, get the 14.8g crystallization, by analysis: the purity of beta-methylnaphthalene is that 99.11wt%, 2-methyl benzo-thiophene content are that 0.36wt%, alpha-methyl-naphthalene foreign matter content are that 0.40wt%, 5-methyl benzo-thiophene foreign matter content are 0.13wt%.
Embodiment 3
Take by weighing 30g beta-methylnaphthalene, 30g dehydrated alcohol, add and have in the stirred type crystallizer of anchor stirrer, elevated temperature to 25 ℃, under 120rpm speed stirs, constant speed of cooling with 3.3K/h is cooled to warm 5 ℃ eventually of crystallizations, filtration obtains the beta-methylnaphthalene crystallization, and the gained crystallization is carried out secondary crystal according to said process, filters at last to obtain the 8.0g crystallization.By analysis: the purity of beta-methylnaphthalene be 99.60wt%, 2-methyl benzo-thiophene content be 0.30wt%, do not detect alpha-methyl-naphthalene impurity, 5-methyl benzo-thiophene foreign matter content is 0.10wt%.
Embodiment 4
Take by weighing 30g beta-methylnaphthalene, 30g Virahol, add and have in the stirred type crystallizer of anchor stirrer, elevated temperature to 22 ℃, under 120rpm speed stirred, the constant speed of cooling cooling with 15K/h added thick beta-methylnaphthalene raw material 0.75g when crystallization begins, be cooled to warm 0 ℃ eventually of crystallization, filtration obtains the beta-methylnaphthalene crystallization, is 0 ℃ washed with isopropyl alcohol subsequently with the 0.9g temperature, obtains the 7.8g crystallization.By analysis: the purity of beta-methylnaphthalene is that 99.26wt%, 2-methyl benzo-thiophene content are that 0.32wt%, alpha-methyl-naphthalene foreign matter content are that 0.29wt%, 5-methyl benzo-thiophene foreign matter content are 0.13wt%.
Embodiment 5
Take by weighing 700g beta-methylnaphthalene, 980g methyl alcohol, add and have in the stirred type crystallizer of anchor stirrer, elevated temperature to 23 ℃, under 180rpm speed stirred, the constant speed of cooling cooling with 0.01K/h added thick beta-methylnaphthalene raw material 0.035g when crystallization begins, be cooled to warm 5 ℃ eventually of crystallizations, filtration obtains the beta-methylnaphthalene crystallization, is that the aqueous isopropanol of 5 ℃ saturated beta-methylnaphthalene divides three washings with the 1050g temperature subsequently, obtains the 225.8g crystallization.By analysis: the purity of beta-methylnaphthalene is that 99.38wt%, 2-methyl benzo-thiophene content are that 0.30wt%, alpha-methyl-naphthalene foreign matter content are that 0.18wt%, 5-methyl benzo-thiophene foreign matter content are 0.14wt%.