KR101547126B1 - Method for purification of tar or pitch at high temperature and high pressure using alipatic compound - Google Patents

Abstract

The present invention relates to a method for purifying a tar or pitch with high purity, comprising the step of mixing one of Tar, a pitch and a mixture thereof with an aliphatic compound at a temperature of 250-380 DEG C and a pressure of 5-100 bar to provide. According to the present invention, uniform and effective mixing between a liquid (tar or pitch) and a liquid (aliphatic compound) is induced, and as a result, the precipitation of impurities that are not dissolved in the aliphatic compound is maximized and the purification efficiency can be increased.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying tar or pitch using aliphatic compounds,

The present invention relates to a method of purifying one of Tar, Pitch and mixtures thereof using an aliphatic compound.

In general, impurities such as ash and quinoline insoluble substances are present in the tar and pitch, and therefore it is required to remove impurities in order to use the carbon material easily. Methods for removing impurities include solvent extraction and filtration methods in which insoluble matter is dissolved by dissolving in a specific solvent, specific gravity separation method using high speed centrifugation, and porous filter method having a specific pore size.

However, in the case of solvent extraction and filtration, there is a disadvantage in that an excessive amount of solvent must be used due to insufficient solvency of the solvent. In the case of the specific gravity separation method, it is not suitable for separation of impurities having a small specific gravity difference. In addition, the porous filter method has a long process time and a large pressure to be applied to the filter, resulting in poor process efficiency. Particularly, when the conventional impurity removing method is applied to a batch type process, the overall process time becomes long, so that the productivity is lowered.

Regarding the purification of tar or pitch, U.S. Pat. No. 5,843,298 discloses a method for producing QI-free coal tar pitch from a coal tar containing quinoline insoluble particles (QI) using a circulation loop comprising a membrane filter and a pump . U.S. Patent No. 5128021 discloses a pitch having a quinoline insoluble content of 2% or less obtained by adding a diatomaceous earth or a carbon-based filtering agent and filtering the mixture at a temperature of 300-425 ° C under a pressure of 10 mbar or less. 4127472 discloses a process for removing quinoline insoluble materials by heating coal tar and / or coal tar pitches in aliphatic or aromatic solvents and atmospheric pressure. However, in the above-mentioned prior art, there is no purification method for maximizing precipitation of impurities by mixing tar or pitch with an aliphatic compound under high temperature and high pressure.

In order to remove impurities present in tar or pitch for carbon materials, solvent extraction and filtration methods using solvents, specific gravity separation methods, and porous filter methods have been used. However, excessive addition of solvent and complex recovery process, poor process efficiency Etc. have been raised. Accordingly, it is desired to provide a purification method for efficiently removing impurities precipitated in one of Tar, Pitch and mixtures thereof by adding a solvent having a low dissolving power to impurities and accelerating the purification reaction .

The present inventors have recognized and solved the problem that the efficiency of purification process of tar or pitch by the conventional organic solvent extraction method, specific gravity separation method, and porous filter method is low. As a result, (Tar or Pitch) - liquid (aliphatic compound) is accelerated and homogenized when used as a solvent and mixed with Tar, Pitch and one of the mixtures thereof, resulting in dissolution in the aliphatic compound The precipitation of undesirable impurities is maximized, and the present invention has been completed.

According to one embodiment of the present invention there is provided a method of making a tar or a mixture comprising a tar, a pitch and a mixture thereof, and an aliphatic compound at a temperature of 250-380 DEG C and a pressure of 5-100 bar A method for high purity purification of pitch is provided.

The aliphatic compound may be at least one compound or mixture selected from the group consisting of aliphatic hydrocarbons of C6 to C25 and kerosene, more preferably aliphatic hydrocarbons of C10 to C18 and kerosene having a boiling point of 230 to 270 DEG C ≪ / RTI > or mixtures thereof.

The weight ratio of the aliphatic compound to one of the Tar, the pitch and the mixture thereof is preferably 9: 1 to 1: 9, more preferably 4: 6 to 6: 4 .

On the other hand, it is more preferable that the temperature is 280-350 DEG C and the pressure is 10-20 bar.

Further, the purification method includes a step of centrifugally removing the impurities from the mixture after the mixing step, and a step of separating and recovering the purified material (purified tar, purified pitch, and a mixture thereof) by distilling the mixture from which the impurities have been removed And the centrifugation may be performed by applying a centrifugal force of 2000 to 4000 x G. [

The purified product may contain 0.0001-0.5 wt% of impurities, wherein the impurities may be quinoline insoluble fractions.

Tar or pitch can be purified with high purity by maximizing the deposition amount of impurities contained in one of Tar, Pitch and mixtures thereof. That is, gravity settling due to the difference in specific gravity of impurities can be effectively induced to increase the purity of the purified tar or pitch, and as a result, it is possible to remove impurities near 90-99.99%. Also, when one of the purified tar, purified tablet, and mixture thereof produced through one embodiment of the present invention is used, it is possible to use a bed of a graphite electrode rod for an electroforming, an anode material for a lithium secondary battery and an electrode material for a supercapacitor Coke can be easily produced.

Fig. 1 is a photograph of a polarizing microscope photograph of the optical structure of a coke prepared from a purified pitch (quinoline insoluble matter 0.12%).
Fig. 2 is a photograph of a polarizing microscope photograph of the optical texture of a coke prepared from a purified pitch (quinoline insoluble matter content: 2.9%).
3 is a schematic view showing a high-temperature and high-pressure refining facility of tar or pitch.

According to one aspect of the present invention there is provided a method of making a tar or pitch comprising a step of mixing one of Tar, Pitch and mixtures thereof with an aliphatic compound at a temperature of 250-380 DEG C and a pressure of 5-100 bar. Of the present invention .

The term 'aliphatic compound' in this context is in stark contrast to aromatic compounds in that it does not include a benzene ring in the intramolecular structure. In particular, the use of an aliphatic compound and an aromatic compound for purifying the tar or pitch of the present invention is very different. In the case of an aliphatic compound, solubility in impurities existing in coal tar or pitch is low, so that impurities can effectively aggregate and precipitate from the mixture. That is, in the case of purifying tar or pitch using an aromatic compound, the purification efficiency is less than 20%, while in the case of using an aliphatic compound, the purification efficiency may be 70-90% or more. In this case, the purification efficiency can be calculated as the amount of impurities removed relative to the amount of impurities remaining in the tar or pitch before purification.

According to a preferred embodiment of the present invention, the aliphatic compound may be at least one compound or mixture selected from C6-C25 aliphatic hydrocarbons and kerosene, more preferably C10-C18 aliphatic hydrocarbons and boiling points 230-270 Lt; RTI ID = 0.0 > C, < / RTI > At this time, the 'kerosene' may mean 'refined oil that can be obtained at a temperature of 130 to 270 ° C. when refining crude oil'. Generally, when kerosene is purified, other impurities including sulfur, aromatic compounds, and the like are removed and the content of aliphatic hydrocarbons becomes higher. Therefore, in the present invention, it is preferable to classify kerosene as an aliphatic compound. The kerosene having a boiling point of 230-270 DEG C can be obtained by fractional distillation of kerosene, but is not limited thereto.

When the number of carbon atoms of the aliphatic hydrocarbon is less than 6, there is a problem that the efficiency of the mutual contact reaction between the liquid phase and the liquid phase is low in a high temperature and high pressure reaction. There is a problem that recovery is not easy. More preferably, one or more compounds selected from the group consisting of C10 to C18 aliphatic hydrocarbons and kerosene having a boiling point of 230 to 270 DEG C are used to produce Tar, pitch and mixtures thereof When purified, the reaction efficiency of mutual contact of the liquid phase and the liquid phase can be improved. That is, it is highly compatible with the object to be purified, and an excellent purification effect can be obtained. As a result, nearly 99.99% of the impurities are removed, and the insoluble matter in the purified product can be contained very little in the range of 0.01-0.25%. Such highly purified tar or pitch of high purity can be very easily used as a raw material for acicular coke.

According to a preferred embodiment of the present invention, one of the Tar, the pitch and the mixture thereof and the aliphatic compound may be mixed in a weight ratio of 9: 1 to 1: 9, more preferably 4: 6 To 6: 4. If the weight of one of Tar, Pitch and mixtures thereof exceeds 9 times the weight of the aliphatic compound, the viscosity of the mixture is too high to easily induce precipitation of the impurities. On the other hand, when the weight of the aliphatic compound is more than 9 times the weight of one of Tar, Pitch, and a mixture thereof, the amount of the solvent is excessively larger than that of the object to be refined, The viscosity of the mixture is lowered and re-contamination of the impurities occurs.

According to a preferred embodiment of the present invention, the mixing of one of the Tar, the pitch and the mixture thereof with the aliphatic compound can be performed more smoothly at a high temperature and a high pressure of 250-380 DEG C and 5-100 bar have. When the tar or pitch is refined under high temperature and high pressure, the boiling point of the material constituting the aliphatic compound is elevated, and therefore, the tar or pitch is present as a liquid phase without evaporation. This makes it possible to uniformly mix and contact the liquid (tar or pitch) - liquid (aliphatic compound) and to accelerate the contact.

As a result, it is possible to maximize the precipitation amount of the impurities which are not dissolved in the aliphatic compound, and when it is separated, the separation efficiency by the specific gravity difference can be increased. Outside of the above range, the purification efficiency is lowered at 250 DEG C and less than 5 bar, and at 380 DEG C and 100 bar or more, the process cost is increased and unnecessary energy is wasted. Furthermore, the more preferable high-temperature and high-pressure conditions may be a temperature of 280 to 350 ° C and a pressure of 10 to 20 bar.

According to a preferred embodiment of the present invention, the purification method comprises centrifuging and removing the impurities from the mixture after the mixing step, and distilling the mixture from which the impurities have been removed to obtain a purified product (one of the purified tar, the purified pitch, And a step of separating and recovering the liquid. According to one embodiment of the present invention, impurities which are not dissolved in aliphatic compounds are precipitated from the mixture and coagulated with each other. At this time, when centrifugal force is applied, the mixture in which a large amount of impurities are aggregated due to the difference in specific gravity sinks to the bottom, do.

The centrifugal force (relative centrifugal force) applied to the centrifugal separation may preferably be 2000 to 4000 x G. When the centrifugal force is less than 2000xG, there is a problem that the acceleration time of separation of the specific gravity difference due to centrifugal force is low and the process time is increased. When the centrifugal force is more than 4000xG, there is a problem in the durability of the centrifugal separator during continuous operation. In addition, when the centrifugal force exceeds 4000 x G, the cost of the apparatus increases, and the acceleration effect of the gravity separation is not significantly increased compared to the desired centrifugal force range. The centrifugal centrifugal separation may be performed by a device such as a screw decanter, but the present invention is not limited thereto, and a method commonly used in the related art can be applied.

Furthermore, the mixture obtained by removing the impurities by centrifugation can be immediately distilled and separated into purified water and an aliphatic compound. However, it is more preferable to collect 50-80% of the upper portion of the volume of the mixture from which impurities have been removed so as to increase the final purity of the purified product, and then distillation is more preferable, and pre-distillation filtering is most preferably performed.

According to a preferred embodiment of the present invention, the impurity may be a quinoline insoluble matter. Since quinoline insoluble matter content is usually the highest in impurities of tar or pitch, the removal of quinoline insoluble matter can be regarded as a criterion for judging the removal of impurities.

According to still another aspect of the present invention, there is provided an apparatus for purifying tar or pitch including a high-temperature and high-pressure reactor, a pressurized gas tank, and a heating unit (see FIG. In the reactor 100, one of Tar, Pitch, and mixtures thereof containing aliphatic compounds and impurities is mixed with each other to cause a contact reaction. Therefore, the reactor may further include a stirring device 101 to smoothly induce the contact reaction of the mixture. The reactor may also include a pressure release valve 102 to recover the elevated internal pressure before elevation. The reactor may be in the form of a vessel so as to contain the mixture therein, but the present invention is not limited thereto.

In addition, the reactor may further include a sample feeding device 130 having a metering pump 131. It is possible to control the mixture ratio of the mixture by quantitatively supplying the amount of the aliphatic compound introduced through the sample supply device.

According to a preferred embodiment of the present invention, the pressurized gas tank 110 is connected to a reactor and supplies gas into the reactor to increase the pressure. The pressurized gas tank is equipped with a gear pump 111 to control the pressure.

Meanwhile, the heating unit 120 is an apparatus for controlling the internal temperature of the reactor. The heating unit may adjust the temperature by an electric resistance or a thermal medium effect, but is not limited thereto.

According to a preferred embodiment of the present invention, the purification apparatus may further include a centrifugal separator 210. The centrifugal separator may be installed in the reactor, or may be installed so that the mixture transferred from the reactor may be separately centrifuged in connection with the reactor. The centrifugal separator is preferably a screw decanter, but is not limited thereto, and it is most preferable that centrifugal force of 2000 to 4000 x G can be given. When the centrifugal force is applied to the mixture through the centrifugal separator, the mixture in which a large amount of impurities are aggregated has a high specific gravity and is settled downward. At this time, an impurity reservoir 211 for recovering the impurity mixture to be precipitated may be further included in the lower portion of the centrifugal separator.

According to a preferred embodiment of the present invention, the purification apparatus may further include a candle filter 220 and a distillation apparatus 230. The candle filter is a device for further purifying the impurity-free mixture. In order to effectively remove residual impurities, the candle filter may have a pore size of the filter of 5-15 탆, more preferably a pore size of 8- 12 m, and most preferably 10 m.

On the other hand, the distillation apparatus is a device for separating tar or pitch from the aliphatic compound in the purified mixture. According to a preferred embodiment of the present invention, the distillation apparatus can also be connected to a storage tank 231 for separating and recovering the final purified product and a recovery tank 232 for recovering the separated aliphatic compound.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are for the purpose of illustrating the present invention more specifically, and the present invention is not limited thereto.

Example

Example  1. Purification of coal tar using high temperature and high pressure equipment and kerosene

150 g of coal tar (by weight of quinoline insoluble matter: 2.8% by weight, measured by ASTM D2318) and 150 g of kerosene with a boiling point of 130-270 ° C were mixed with each other and fed into a reactor capable of giving high temperature and high pressure. At this time, the temperature inside the reactor was kept at 350 占 폚 while the stirring device was operated. The pressure inside the reactor was kept constant at 10 bar by supplying nitrogen through a pressurized gas tank valve connected to the reactor. After maintaining 90 minutes under the above conditions, the temperature was lowered to room temperature and naturally cooled. The release valve at the top of the reactor was opened to lower the pressure in the reactor to normal pressure.

The reactor bottom valve was then opened and the mixture was transferred to a decanter (screw decanter) to operate the decanter. As a result, centrifugal force was applied to the mixture, and in this process, the mixture with a large amount of impurities precipitated into the decanter under the specific gravity difference. Finally, the centrifuged mixture was taken from the top by 80% of the total volume, put into a distillation apparatus, and the purified coal tar in the mixture was separated and recovered. The amount of quinoline insoluble matter contained in the coal tar was measured through the solubility analysis method according to ASTM D2318. The quinoline insoluble content in the purified coal tar sample was 0.2 wt%.

Example  2. High temperature and high pressure equipment and Atmospheric pressure  Purification of coal tar with kerosene 230-270 ℃

150 g of coal tar (2.8% by weight of quinoline insoluble matter, measured by ASTM D2318) was purified in the same manner as in Example 1 except that kerosene oil (150 g) at a boiling point of 230-270 캜 (atmospheric pressure) was used, And separated and recovered. The amount of quinoline insoluble matter contained in the coal tar was measured by solubility analysis method according to ASTM D2318. The amount of quinoline insolubles in the purified coal tar sample was 0.09 wt%.

Example  3. Using high-temperature, high-pressure equipment and kerosene Pitch  Tablet and coke manufacturing

The coal tar (2.8% quinoline insoluble content, as measured by ASTM D2318) was distilled using a single distillation apparatus to prepare a soft pitch (quinoline insoluble matter 3.5%, measured by ASTM D2318, softening point 35 ° C). 150 g of the prepared soft pitch and 150 g of kerosene oil fraction having a boiling point of 230-270 캜 (standard pressure) used in Example 2 were subjected to high temperature and high pressure purification in the same manner as in Example 1. As a result, the quinoline insoluble fraction in the purified pitch was measured (measured by ASTM D2318) at 0.12 wt%.

Subsequently, 50 g of the obtained tablet pitch was charged into a tube-shaped small calking apparatus manufactured separately, and the pressure was adjusted to 10 bar by applying nitrogen pressure. After that, the caulking device was put into the heating furnace preheated to 500 degrees Celsius and maintained for 5 hours. Thereafter, the caulking apparatus was taken out of the heating furnace, cooled to room temperature, the release valve was opened to adjust the caulking apparatus to normal pressure, and the coke sample produced in the caulking apparatus was desorbed.

The desorbed coke sample was cut into a volume of 1 cm < ³ > or more to observe the optical structure using a polarizing microscope, and then subjected to molding using an epoxy resin and surface polishing (polishing) through a fine grinding apparatus. As a result of observing the optical tissue morphology using a polarizing microscope, it was confirmed that the coke produced from the purified pitch (quinoline insoluble matter 0.12%) exhibited a flow domain form, which is a type of anisotropic optical tissue (see FIG. This is a pattern that can be found in a typical needle coke, with the coke texture pattern aligned in the uniaxial direction.

Comparative Example  1. Comparison of purification efficiency of coal tar by refining method or solvent type

Comparative Example  1-1. Purification using centrifuge

150 g of the same coal tar as in Example 1 and 150 g of kerosene were used and stirred with a mechanical stirrer for 30 minutes while heating to 60 캜. The mixed samples were transferred to a container for centrifugation and subjected to centrifugation at a centrifugal force of 4,000 x G for 5 minutes in a high-speed centrifuge. After that, 80% of the upper portion of the centrifuged sample was collected (by volume) and the components of the refined coal tar sample were measured by the solubility analysis method according to ASTM D2318. As a result of the measurement, quinoline insoluble matter in the purified coal tar sample was measured to be 0.8 wt%.

Comparative Example  1-2. Refining with aromatic compounds

The coal tar was purified in the same manner as in Example 1, except that kerosene was replaced with 150 g of an anthracene oil, which is an aromatic compound, with an additive solvent. As a result, the quinoline insoluble fraction in the purified coal tar sample was measured (measured by ASTM D2318) at 2.5 wt%.

Comparing Example 1 with Comparative Examples 1-1 and 1-2, the use of kerosene, which is an aliphatic hydrocarbon, as a solvent is effective in inducing flocculation and precipitation of impurities as compared with the case where an aromatic compound is used. This phenomenon can be confirmed to occur more actively, especially at high temperature and high pressure. That is, as can be seen from Table 1, the impurities contained in the tar were effectively removed during the high-temperature and high-pressure reaction rather than the centrifugation, and it was found that the aliphatic compound was more suitable for the purification agent than the aromatic compound.

division Purification Target Refined solvent Refining method Insoluble matter content before purification Insoluble matter content after purification Purification efficiency ¹⁾ Comparative Example 1-1 coal tar
150g Kerosene
150g Centrifugation 2.8% 0.8% 71.4% Comparative Example 1-2 coal tar
150g Anthracene oil
150g High temperature, high pressure 2.8% 2.5% 10.7% Example 1 coal tar
150g Kerosene
150g High temperature, high pressure 2.8% 0.2% 92.8%

1) Purification efficiency: {(content of removed impurities) x 100} / (impurities remaining in tar or pitch before purification)

Comparative Example  2. Purification of coal tar using kerosene with boiling point of 130-220 ℃

150 g of coal tar (150 g) was refined at a high temperature and a high pressure in the same manner as in Example 2 except that kerosene oil (150 g) having a boiling point of 130 ° C. or more and 220 ° C. or less (based on an atmospheric pressure boiling point) was used as a solvent. As a result, quinoline insoluble matter in the final purified coal tar sample was measured at 1.2 wt% (solubility analysis method, ASTM D2318).

From the results of the purification of Example 2 and Comparative Example 2, it can be seen that even though the same aliphatic compound is used, the purification effect varies greatly depending on the boiling point (see Table 2 below). As a result, it was found that the refining efficiency is higher when kerosene having a boiling point of 230-270 ° C is used than kerosene having a boiling point of 130-220 ° C.

division Purification Target Refined solvent Refining method Insoluble matter content before purification Insoluble matter content after purification Purification efficiency ¹⁾ Comparative Example 2 coal tar
150g Boiling point 130-220 ℃ kerosene
150g High temperature, high pressure 2.8% 1.2% 57.1% Example 2 coal tar
150g Boiling point 230-270 ℃ Kerosene 150g High temperature, high pressure 2.8% 0.09% 99.6%

1) Purification efficiency: {(content of removed impurities) x 100} / (impurities remaining in tar or pitch before purification)

Comparative Example  3. Using aromatic compounds Pitch  Tablet and coke manufacturing

After soft pitch was prepared in the same manner as in Example 3, 150 g of anthracene oil was added to 150 g of soft pitch instead of kerosene, followed by high-temperature and high-pressure purification. The result of conversion and quantification of the quinoline insoluble matter in the pitch samples purified by the solubility analysis method (ASTM D2318) was measured to be 2.9% by weight, and a coke was prepared in the same manner as in Example 3 using the purified pitch. As a result of observation of the optical tissue morphology of the coke using a polarizing microscope, it was confirmed that a mosaic morphology, which is a kind of isotropic optical structure, appears in the coke prepared from the purified pitch (quinoline insoluble matter: 2.9%) (see FIG. 2) .

division Purification Target Refined solvent Refining method Insoluble matter content before purification Insoluble matter content after purification refine
Efficiency ^{1 )} Coke morphology Comparative Example 3 Pitch
150g Anthracene oil
150g High temperature, high pressure 3.5% 2.9% 17.1% Mosaic form
(Isotropic) Example 3 Pitch
150g Boiling point 230-270 ℃ Kerosene 150g High temperature, high pressure 3.5% 0.12% 99.4% flow domain type
(Anisotropy)

1) Purification efficiency: {(content of removed impurities) x 100} / (impurities remaining in tar or pitch before purification)

As in the case of the coal tar purification, it was confirmed that the purification efficiency of the pitch was superior when the aliphatic compound was used than the aromatic compound in the purification of Example 3 and Comparative Example 3. That is, when the aliphatic compound is refined at high temperature and high pressure, it is possible to purify the pitch with high purity. Thus, the purified pitch is very suitable for producing the needle-like coke used as the material of the secondary battery, the super capacitor electrode material, .

100: high-temperature and high-pressure reactor 101: stirrer
102: Pressure release valve 110: Pressurized gas tank
111: Gear pump 120:
130: sample feeding device 131: metering pump
210: centrifugal separator 211: impurity reservoir
220: Candle filter 230: Distillation device
231: purified water storage tank 232: aliphatic compound recovery tank

Claims (10)

Tar, Pitch and mixtures thereof and aliphatic compounds.
Lt; RTI ID = 0.0 > 280-350 C < / RTI > and a pressure of 10-20 bar,
Wherein the aliphatic compound is at least one compound selected from the group consisting of C10 to C18 aliphatic hydrocarbons and kerosene having a boiling point of 230 to 270 占 폚.
delete delete The method according to claim 1,
Wherein the weight ratio of one of Tar, Pitch and mixtures thereof to aliphatic compound is from 9: 1 to 1: 9.
5. The method of claim 4,
Wherein the mixed weight ratio is 4: 6 to 6: 4.
delete The method according to claim 1,
The purification method may be carried out after the mixing step
Centrifuging and removing impurities from the mixture; And
And distilling the mixture from which the impurities have been removed to separate and recover the purified product.
8. The method of claim 7,
Wherein the centrifugal separation is performed by applying a centrifugal force of 2000 to 4000 x G.
8. The method of claim 7,
Wherein the purified product contains 0.0001-0.5 wt% of impurities.
8. The method of claim 7,
Wherein the impurity is quinoline insoluble fraction or tar.

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