JPH0948978A - Improved method for producing solvated mesophase pitch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to obtain a high yield of solvated mesophase pitch by subjecting a heavy aromatic pitch fraction to heat soaking in the presence of a solvent having a solvating ability.

SOLUTION: An aromatic raw material is subjected to heat soaking in a heat soaking oven 10 to convert into an isotropic heat-soaked pitch, while a light cracking product is removed out of the system. The pitch is combined with an extractant with a mixer/settler 20 to give a heavy faction, while a light fraction is removed out of the system. The heavy fraction together with a heavier solvent is subjected to solvating and heat soaking treatment in an oven 30 to give a heat-soaked solvated pitch, while a light cracking product and a light solvent are removed out of the system. The pitch is combined with a heavier solvent with a mixer/settler 40 to give a solvated pitch as heavy as desired, while a light fraction is removed out of the system.

COPYRIGHT: (C)1997,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an improved process for producing solvated mesophase pitch. By following the method of the present invention, solvated mesophase pitches, and in particular thermosettable solvated pitches, with higher yields that can be achieved using other methods known in the art, are obtained. It can be manufactured with feasibility.

[0002]

Mesophase pitch is a carbon material having an ordered liquid crystal structure. It has excellent physical properties and is manufactured from mesophase pitch.
It is believed that it is the mesophase pitch liquid crystal structure that imparts to the fibers, in particular.

Various methods are well known in the art for making mesophase pitches. One such method is disclosed in US Pat. No. 4,208,267 (Dieffendorf). In this patent document, a mesophase form fraction having a quinoline insoluble matter (QI) content of less than 25%.
The solvent fractionation method is used to obtain the er fraction). The Dieffendorf patent teaches treating isotropic pitch with a solvent to provide a solvent insoluble fraction having a sintering point of less than 350 ° C. and separating the solvent insoluble fraction from a solvent solution. The solvent insoluble fraction is then
Deformable pitch containing more than 100% mesophase (defor
In order to convert into a mable pitch), it is heated to a temperature of 230 to 400 ° C.

US Pat. No. 4,277,324 (Greenwood) teaches that QI and high softening point compounds are undesirable in pitches intended for spinning and can be removed from pitches by solvent extraction methods. There is. In the Greenwood method, a flux liquid (solvent) is added to the pitch to render it pitch fluid and suspend any insoluble pitch particles in solution. The suspended particles are removed from the solution and the solution is treated with a second liquid (antisolvent), precipitating a significant portion of the fluid pitch. The precipitated pitch is then removed from the fluid and used to make carbon artifacts.

US Pat. No. 4,184,942 (Angier) discloses a neo-mesophase former fraction (n) in the pitch due to thermal soaking of a low QI isotropic pitch.
It is taught that the amount of eomesophase former fraction) increases. After thermal soaking, the neomesophase former fraction is separated by solvent extraction.

US Patent Application No. 07 / 762,711 (Romain) discloses solvated mesophase pitches with improved handling properties. Since solvated mesophase pitch melts at a temperature that is at least 40 ° C. lower than the same pitch in unsolvated form, the solvated pitch can be successfully processed and spun at lower temperatures. Also, spinnable solvated pitches are unsuitable if not solvated, or where carbonization occurs making these pitches unsuitable for spinning 350.
It can be prepared from heavy aromatic pitch that melts above ° C. Thus, solvated mesophases effectively increase the range of heavy aromatics that produce useful pitch. With this new application of heavy pitch, it is desirable to obtain such heavy fractions in a workable manner with good yields.

Heavy mesophase-forming aromatic pitch (mes
Typical thermal soaking techniques (ie, increasing the severity of thermal soaking conditions) that have been tested in an attempt to increase the yield of ophase-forming aromatic pitch have some serious drawbacks. Increasing the severity of thermal soaking usually increases the yield of heavy mesophase-forming aromatic pitch, but this method produces isotropic phase pitch (iso
including tropic phase pitch) and mesophase pitch 2
Phase products will typically be produced. Two-phase pitch products are notoriously difficult to process, especially when continuous processing systems are required that require the transfer of two-phase mixtures. Typically, the two phases have distinct physical properties, such as molecular weight, viscosity, density and melting point. During the heat soaking process, the mesophase portion tends to become very viscous, resulting in carbonization within the processor and ultimately to a solid coke state. The viscous mesophase and / or solid coke will block the furnace, transfer tubes, associated vessels and equipment. Even if the above method does not go this far, slight carbonization of the pitch tends to lead to insoluble contaminants within the mesophase pitch product. On the other hand, the potential yield of heavy solvated mesogens is undesirably low if the heat soaking conditions are kept mild to prevent the formation of heat soaked pitches containing two-phase mesophases. The present invention seeks to avoid the processing problems as outlined above and further improve the yield of the desired mesophase pitch product.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a highly workable process for obtaining high yields of heavy solvated pitch. In its most basic form, the present invention provides a heavy aromatic pitch fraction.
pitch fraction) to a solvating solvent
heat soaking in the presence of t) and the larger heavy aromatics produced by the heat soaking.
It includes collecting the omatic). The heat soaking step and the recovery step can be performed as continuous steps.
Alternatively, the steps of heat soaking the heavy aromatics fraction and recovering the larger heavy aromatics may include:
Can be done simultaneously.

A particularly useful aspect of the present invention results in the preparation of a thermosetting solvated mesophase pitch. Thermosetting solvated mesophase pitch is meltable and flowable when solvated, but produces a thermosetting heavy hydrocarbon residue when no solvating solvent is present in the pitch. To do. During heating, the thermosetting, solvated mesophase pitch first transforms into an infusible carbon material without appreciable melting.

The present invention comprises a highly workable process for obtaining heavy solvated mesophase pitch from heavy pitch in high yields. The present invention provides for the step of heat soaking the heavy aromatic pitch fraction in the presence of a solvating solvent under suitable conditions to form larger heavy aromatic molecules, and The step of recovering large heavy aromatic solvated pitch molecules is included.

The heavy aromatic pitch fraction used as raw material in the present invention is graphitizable containing mesophase pitch or mesophase containing pitch with little or no ash contamination.
It is a mixture of aromatic hydrocarbons. In the dry (non-solvated) state, the heavy aromatic pitch fraction is
It will soften in the range of 150-400 ° C. Preferably the pitch fraction will melt below 400 ° C. Some types of mesophase pitches and mesophase containing pitches may be unsuitable raw materials for use in the present invention. The unfavorable feedstocks include certain thermal mesophases and thermal sparge mesophases, and when pitch is combined with a solvating solvent, some of these materials It remains an infusible solid.

Heavy aromatic pitch fractions are commercially available. For example, a heavy aromatic pitch feed suitable for use in the present invention is commercially available from Mitsubishi Gas Chemical Company (Tokyo, Japan)
240 Synthetic mesophase pitch.
As will be seen later in this specification, the heavy aromatic pitch fraction can also be obtained from a heat-soaked aromatic feedstock.

The hot soaking of the heavy aromatic pitch fraction in the process of the invention is carried out in the presence of a solvating solvent.
It is carried out under suitable conditions to promote an increase in the number of desired heavy aromatic molecules in the pitch. Such conditions include:
Included is subjecting the heavy aromatic pitch fraction to a temperature in the range of 360-520 ° C. and at a pressure sufficient to maintain the solvating solvent in a liquid state at the selected temperature. Such pressures are generally 14.7-100.
0 psia is 5 minutes to 24 hours. The preferred temperature for thermal soaking of the heavy fraction is 380-460 ° C.

In the present invention, it is important to carry out the heat soaking step of the heavy aromatic pitch fraction in the presence of a solvating solvent. In general, this requires that the heat soaking step be performed in a closed vessel or other suitable system that maintains the solvating solvent in intimate contact with the pitch being heat soaked. The closed vessel would also allow the pressure to be in the range required to carry out the method of the present invention.

The solvating solvent used in the thermal soaking process is a solvent which, when combined with the heavy pitch fraction, dissolves in the heavy pitch fraction to a sufficient extent to form a solvated pitch. The solvated pitch formed by the combination with the solvating solvent is
It melts or flows at a temperature at least 40 ° C. below the melting point of the same pitch fraction in unsolvated form.

Suitable solvating solvents of the present invention include 1 to 4
One or more selected from the group consisting of organic solvents having a structure containing one aromatic ring are included. However, the above structure
It may optionally contain 1, 2 or 3 hydroaromatic rings. The structure of the solvating solvent is, in some cases,
C ₁ -C ₄ -alkyl groups (ie methyl, ethyl,
It may be substituted with one or more substituents selected from the group consisting of propyl and butyl). Preferred solvents have an average solubility parameter (δ) in the range of 7.0-11.5.

Specific solvating solvents that can be used in the present invention include one or more solvents selected from the group consisting of benzene, xylene, anthracene, phenanthrene, chrysene, pyrene, tetralin and naphthalene. Natural aromatic distillates containing solvating solvents having the structure described in the preceding paragraph can also be used as solvating solvents in the present invention. Such distillate oil is
Obtained from petroleum aromatics, coal tar, and ethylene tar.

During the thermal soaking of the heavy aromatic pitch fraction, the solvating solvent has a solvent to pitch ratio of
The solvent is present in the range of 0.05 to 5.0 parts per part of pitch. At the pitch saturation point, up to about 40% by weight, but typically about 20-25% by weight of solvating solvent can be dissolved in the heavy pitch fraction.
At the saturation point, the solvated pitch can be melted at a temperature 200 ° C or more below the melting point of the same pitch in the unsolvated form. Reducing the melting point ensures that the very heavy pitch fraction, including the desired thermoset fraction, maintains high flowability and processability during thermal soaking.

Recovery of the larger heavy aromatics produced by thermal soaking is typically done using the technique of solvent extraction. The product of the thermal soaking step is subjected to intimate contact with the extraction solvent at elevated temperature to separate the material into a solvated residue containing larger heavier aromatics. The solvated residue is recovered and the liquid extract is removed. The extraction is usually carried out in a closed vessel to allow the solvent to be held in the system and the pressure in the system to reach the desired level at which the solvent can be maintained in the liquid state at the extraction temperature. The extraction pressure required to carry out the extraction will vary depending on the solvent used, but a suitable pressure range for carrying out this step of the invention is attributed to the range of 14.7 to 1000 psia. . Extraction of the larger heavier aromatics produced by solvated thermal soaking is performed at a solvent to pitch ratio of 0.25 to 5.0 parts solvent to 1 part pitch.
Those skilled in the art will appreciate that if the desired result is simply extraction,
It will be appreciated that the extraction temperature should be kept below the reaction temperature of the pitch. The temperature at which only extraction is performed is
It can be performed in the range of about 200 to 400 ° C.

The conditions under which the extraction is carried out are selected to achieve the desired hardness of the larger heavier aromatics in the insoluble pitch fraction. As a general rule, by using solvents with higher solubility parameters and higher solvent / pitch ratios in the extraction process, harder and higher melting point insolubles are obtained. However, these conditions also generally result in lower yields of harder products.

The desired larger heavy aromatics soften above 350 ° C. when removed of solvent and dried. At these temperatures, the dried larger heavier aromatics are:
Converts to coke at a noticeable rate. Preferably, the larger heavy aromatics soften above 450 ° C or 500 ° C. In general, the larger heavy aromatics that soften above 500 ° C. are thermosettable, that is, if they soften, they undergo rapid thermal solidification upon heating to a non-melting state. . Thus, when the solvent is removed and dried, the heavy aromatics never melt completely.

The heavy solvated pitch product of the present invention contains larger heavy aromatic molecules and solvating solvents. The larger heavy aromatic molecules have a dry softening temperature above 350 ° C, preferably above 450 ° C, most preferably above 500 ° C. The heavy aromatic pitch fraction used as a feedstock for the solvated thermal soaking process of the present invention generally comprises a softer material that softens in the range of 150-400 ° C. Preferably,
The heavy aromatic pitch fraction melts below 400 ° C, allowing handling in the molten state without appreciable coking.

The softening and melting temperatures of the dry pitch are measured by hot stage microscopy. By using this technique, pitch samples are ground to a size of about 200μ or less and distributed thinly in an aluminum pan. The sample is heated on a Leitz 1350 thermal stage under a slight nitrogen purge with a planned initial temperature increase of 20 ° C per minute after a rapid initial heating to 250 ° C. The softening temperature is recorded as the temperature at which 10% of the pitch particles exhibit apex and side roundness. Changes in surface gloss can also be detected. Melt temperature is measured when the flow or spread of the fluid pitch is first observed around the particles. Melting typically occurs at 10-50 ° C above the softening temperature.

Whether thermal hardening of the pitch is observed depends on
It appears to depend on the heating rate of the sample and the thermal reaction rate of the pitch. Thermal cure is observed when the thermal reaction rate of the pitch exceeds the heating rate of the pitch. Therefore, at high heating rates it is unlikely to observe thermal cure, while at low heating rates it is likely to observe thermal cure. It is also pointed out that higher softening point pitches exhibit thermosetting behavior at higher heating rates. Because the thermal reaction will be faster at these higher pitches achieved without melting.

The same higher boiling point solvating solvents mentioned for use in the thermal soaking of heavy pitch fractions are used as the extraction solvent in the recovery of the larger heavy aromatics produced by thermal soaking. Suitable for. Suitable extraction solvents of the present invention include one or more solvents selected from the group consisting of organic solvents having a structure containing 1 to 4 aromatic rings. However, the above structure may optionally include 1, 2 or 3 hydroaromatic rings. The structure of the above solvent may optionally be substituted with one or more substituents selected from the group consisting of C ₁ -C ₄ -alkyl groups (ie methyl, ethyl, propyl and butyl). Preferred solvents are
It has a solubility parameter (δ) in the range of 7.0 to 11.5.

Specific extraction solvents that can be used in the present invention include one or more solvents selected from the group consisting of benzene, xylene, anthracene, phenanthrene, chrysene, pyrene, tetralin and naphthalene. Natural aromatic distillates containing the extraction solvent having the structure described in the preceding paragraph can also be used as the extraction solvent of the present invention. Such distillates can be obtained from sources such as petroleum aromatics, coal tar, and ethylene tar.

The step of heat soaking the heavy aromatic pitch fraction in the presence of a solvating solvent, and the step of extracting the larger heavy aromatic material produced in the heat soaking of the heavy aromatics optionally comprises , Can be combined in a single step so that thermal soaking of pitch and extraction of heavy aromatics occur simultaneously. When the two steps are combined, the solvent to pitch ratio must be maintained at a level sufficient to allow both the solvation step and the extraction step to occur simultaneously. When the two steps are combined, the solvent is 0.25 to 1 part pitch.
A solvent to pitch ratio in the range of 5.0 parts is required. The temperature of the process is in the heat soaking temperature range, ie 360
It should be maintained at ~ 520 ° C, preferably 380-460 ° C. The process pressure should be maintained at the process temperature at a pressure sufficient to maintain the solvent in the liquid state. Generally, pressures in the range 14.7-1000 psia will be sufficient.

It is desirable to maintain the pitch and solvent in a reasonably homogeneous mixture during the heat soaking and recovery process of the larger heavy aromatic molecules. This is simply due to the stirring action of the heated solvent and pitch mixture.
n) or mechanically, for example by the use of mixing means such as stirrers, paddles, agitators and pumps around the loop.

The invention can also be carried out by starting with an aromatic feedstock, treating this feedstock to obtain the desired heavy pitch fraction, and treating this heavy pitch fraction as described above. In this case, the method of the present invention comprises the step of heat soaking the aromatic raw material to obtain an isotropic heat soaked pitch containing a heavy pitch fraction, wherein the weight of the isotropic heat soaked pitch is Extraction and separation of the heavy pitch fraction with a suitable solvent, suitable conditions for promoting the formation of larger heavy aromatic molecules in the presence of a solvating solvent. Thermally soaking down, as well as recovering the larger heavier aromatic molecules produced by thermal soaking of the heavy fraction.

By those skilled in the art, heat soaking the aromatic feedstock to produce a heat soaked isotropic pitch and extracting the heavy hula cushion of the heat soaked pitch. It will be appreciated that the process uses fairly conventional techniques. The detailed process of these steps is shown below.

The aromatic feedstock from which the heavy aromatic fraction is obtained is typically a mixture of aromatic hydrocarbons obtained either as a residue of a petroleum refining process or as a distillate. Preferably, the feedstock is a coal tar, a distillate cut originating from a gas oil, or a coker feed such as refinery decant oil, thermal cracking tar and ethylene pyrolysis tar. feed). One of ordinary skill in the art will appreciate that an ideal feedstock would have very low ash and other particulate contaminants.

Thermal soaking of aromatic raw materials is intended to produce hot soaked isotropic pitch. This heat soaking treatment is carried out at a temperature in the range of 360 to 570 ° C. for 2 minutes to 48 hours, approximately atmospheric pressure to 90 degrees
It is carried out under pressure up to 0 psia. The pressure applied during this thermal soaking step is sufficient to ensure that a substantial amount of low boiling petroleum oil in the feed does not evaporate in the thermal soaking process.

Solvent extraction and separation of the heat-soaked heavy fraction of isotropic pitch are carried out by the usual methods with a solvent or solvent mixture having a nonpolar solubility parameter (δ) in the range of 7-10. Be seen. Unsubstituted or short-chain alkyl-substituted mono- and bicyclic aromatic and hydroaromatic hydrocarbons are suitable solvents for the extraction process. Preferably, the solvent is toluene, xylene, mesitylene, naphthalene, tetralin, and the following formula:

Embedded image

(Wherein R represents a linear or branched, unsubstituted or substituted C ₁ -C ₄ -alkyl group) selected from the group consisting of benzene substituted with an alkyl group. Be done. Mixtures of these aromatic or hydroaromatic solvents with non-aromatic compounds such as paraffins and cycloparaffins are also suitable solvents. For example, heptane and cyclohexane are preferred non-aromatic solvent mixture components.

The extraction of isotropic pitch can be carried out in the atmosphere or under elevated temperature and pressure conditions. Preferably, an elevated temperature of 150-350 ° C. is used with sufficient pressure to keep the solvent as a liquid. Supercritical conditions of solvent temperature and pressure can also be used to extract isotropic pitch.

The amount of solvent used in this extraction step is about 2 to 20 parts of solvent to 1 part of pitch. Preferably, 3-8 parts solvent per part pitch is used to extract the heavy fraction. The heavy pitch fraction thus obtained by this method is a mixture of graphitizable aromatic hydrocarbons. Preferred heavy pitch fractions are mesophase pitches with little or no ash contamination, or mesophase containing pitches.

After the extraction and separation steps, a certain amount of extraction solvent will be retained by the pitch. If the desired solvating solvent for the heavy pitch fraction differs from the solvent used to extract and separate the heavy pitch fraction, the heavy pitch fraction may require slightly different treatment. The solvent used in the extraction to obtain the heavy pitch fraction can be removed by techniques such as vacuum stripping and then the desired solvating solvent can be added. Alternatively, if the desired solvating solvent has a higher boiling point, the container in which the pitch is treated has vent holes at a suitable temperature to allow the lower boiling solvent to escape. You can just open the.

The step of heat soaking the aromatic raw material and the step of extracting and separating the heavy pitch fraction provide the raw material used in the subsequent solvated heat soaking step. It will be appreciated that the steps of heat soaking the heavy pitch fraction in the presence of a solvating solvent and recovering the larger heavy aromatic molecules are the same as described above.

The present invention can be carried out in batch quantities or in a continuous process as shown in FIG. FIG.
Figure 1 shows a flow diagram illustrating a continuous process in which aromatic feedstock is converted to solvated mesophase pitch. In FIG. 1, aromatic raw materials are stored in a hot soaking furnace 1 from a storage location.
It is transported to 0 and converted into heat-soaked isotropic pitch and a small amount of light cracking product. The hot soaked isotropic pitch is combined with the extraction solvent in the mixer / settler 20, while the light cracking products are removed from the process stream. In the mixer / settler 20, the pitch is separated into a heavy solvated pitch fraction, as well as a light fraction and solvent, the latter being removed from the reaction stream. The heavy fraction is then subjected to solvated thermal soaking in the furnace 30. This thermal soaking
Optionally, it can be done in the presence of a larger heavier solvent. Heavy heat soaked solvated pitch is the desired product of the solvated heat soak process step, while light cracking products and light solvent are removed from the process stream. The heavy heat soaked fraction is combined with the heavier solvent in the second mixer / settler 40. A second mixer / settler 40 separates the material into the desired heavy solvated pitch end product, and a lighter fraction containing the extraction solvent, the latter from the product stream. To be removed.

Those skilled in the art have found that when starting with a heavy pitch fraction, such as mesophase pitch, the process shown in FIG. 1 is simplified by eliminating the raw heat soaking part of the process and the first extraction part. Understand what can be done. Also, in other embodiments, the thermal soaker 30 and the mixer / settler 40 can be combined into a single processing unit.

[0041]

The present invention will be further described in the following examples and comparative examples.

Example 1 Mid-continent refinery decant oil having a nominal boiling point of 427-482 ° C.
il) samples were heat soaked for 3 hours at 441 ° C. and 60 psig under a nitrogen atmosphere. The yield of heat soaked pitch was calculated to be 74.2%. Optical microscopy revealed that the pitch was 100% isotropic.

Then, an isotropic pitch extraction was carried out using xylene as solvent at a solvent: pitch ratio of 5: 1 and 240
It was carried out at a temperature of ° C and a pressure of 105 psig. 1 by extraction
9.0% xylene insoluble matter was obtained. The xylene insoluble material was found to be fluid at the extraction temperature of 240 ° C. when solvated. To remove the xylene solvent, a sample of xylene insolubles obtained from the extraction was dried. Melt test of dried xylene insoluble material was performed at 20 ° C under nitrogen atmosphere.
It was performed by heating the xylene insoluble matter at a rate of / min. According to the melting test, the dry xylene insoluble matter is 36
It became clear that it started to soften at around 2 ° C and melted at 381 ° C.

The dried xylene insoluble matter was placed in a closed container, and heat-soaked at 413 ° C. and a pressure of 5 psig for 5 hours in a nitrogen atmosphere in the presence of 22% by weight of phenanthrene. This thermal soaking step resulted in a solvated mesophase pitch. It was determined by optical microscopy to be 98.3% mesophase.
This solvated mesophase was calculated to contain about 20% by weight phenanthrene. The pitch solvated with phenanthrene was observed to be a viscous fluid at 267 ° C. It was found that the dried pitch softened at 408 ° C and melted at 470 ° C.

The solvated mesophase was extracted by extracting phenanthrene solvated pitch from the second stage thermal soaking using phenanthrene with a solvent: pitch ratio of 1: 1 (calculated based on dry pitch). Pitch was produced with a yield of 45.9%. This material is 27
It was observed to be a viscous fluid at a temperature of 5 ° C. The dried pitch sample was tested and found to begin to soften at about 530 ° C. The maximum softening of dry pitch is about 5
Observed at 49 ° C. At this temperature it was shown that about 80% of the pitch samples had softened to the consistency of viscous glass. No further melting or flow was observed as the temperature was further increased at a rate of 20 ° C. per minute. When continuously heated to 600 ° C., the pitch solidified (heat-cured).

Overall of thermosetting solvated mesophase pitch obtained from distillate feedstock starting material
The yield is 6.1%.

Comparative Example 1 It was confirmed that the hot soaked isotropic pitch used in Example 1 contained no significant amount of thermosetting mesogen prior to the second solvated hot soak step. Comparative Example 1 was performed for illustration purposes. A portion of the pitch heat soaked at 441 ° C. for the same 3 hours used in Example 1 was extracted for 30 minutes at 340 ° C. under a pressure of 122 psig with a solvent: pitch ratio of 8: 1. I served. The solvent used for the extraction was a mixture of tetralin and phenanthrene in the ratio of 80:20, respectively.

This extraction gave a solvated mesophase pitch in an amount of 3.9%. This yield corresponds to a yield of 2.9% from the distillate feedstock.

The dried xylene insoluble matter was heated under a nitrogen atmosphere at a rate of 20 ° C./minute. It was observed that the xylene-insoluble matter began to soften at 414 ° C and melted at 434 ° C. Under more stringent extraction conditions, thermosetting mesogens that melt at higher temperatures may have been obtained, but the overall yield of pitch product would have been less than 2.9%.

Comparative Example 2 Comparative Example 2 was performed to show that a two-phase pitch is produced by extending the first heat soaking to produce a noticeable amount of thermosetting mesogen. It will be recalled that the two-phase pitch is difficult to process because it causes coking in the reactor and related equipment.

The Central American Continental Refinery decant oil distillate having a boiling point of 427 to 482 ° C. used in Example 1 was heat-soaked at 441 ° C. for 5.3 hours under a nitrogen atmosphere of 60 psig. The yield of heat soaked pitch was calculated to be 71.8%. The heat-soaked pitch formed a layer of mesophase pitch that adhered to the reactor walls and was also suspended in the isotropic pitch. The total mesophase pitch content was estimated to be 2.5%.

The mesophase pitch produced by this method did not soften or melt during heating to 600 ° C. at a rate of 20 ° C./min in a nitrogen atmosphere. Therefore, the mesophase pitch and isotropic pitch produced by this method would be very difficult (or impossible) to transfer from the thermal soaking vessel to the mixer / settler. The result is a method that cannot be operated in an economical, continuous manner.

The pitch obtained in Comparative Example 2 was changed to 340 ° C.
Then, 3 parts by the ratio of 8 parts of solvent to 1 part of pitch.
Extracted for 0 minutes. The solvent used was a mixture of tetralin and phenanthrene in a ratio of 80:20, respectively. It was noted that all pitches were solvated. The solvated mesophase insoluble matter was recovered and the yield of the insoluble matter was calculated to be 14.7%. This 14.7% yield corresponds to an overall yield of 10.6% from the fractionated oil feedstock.

This insoluble material was determined to be 100% anisotropic solvated mesophase. The melting test performed on the insoluble matter softens the insoluble matter at 508 ° C.
It was shown to melt at 542 ° C. The results show that these materials are slightly thermoset.

Example 2 A portion of the thermosetting solvated pitch product of Example 1 was formed into a filamentary carbon artifact using the method of melt spinning. A sample of the pitch product of Example 1 was placed in a feed cylinder in tune with a heater and a possible piston. The pitch was heated to melt and pressure was applied by a piston to force the melt pitch out of a 4 mil diameter, 12 mil long capillary. 8 this solvated pitch
The fibers were spun at 70 psig and 298 ° C.

On microscopy, the fibers produced by this method contained the drawn mesophase regions typically observed in high performance mesophase pitch carbon fibers.

[Brief description of drawings]

FIG. 1 is a flow diagram illustrating a continuous process in which an aromatic feedstock is converted to solvated mesophase pitch.

[Explanation of symbols]

10 ... Thermal soaking furnace, 20 ... Mixer / settler,
30 ... Furnace, 40 ... Mixer / Setler

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Edward Jay Nanny, State of Oklahoma, United States 74604, Ponca City, Bluestem 2521 (72) Inventor Mark W. Carrell, State of Oklahoma 74604, Ponca City, United States Turner 3201

Claims (17)

[Claims] 1. (a) a step of combining a heavy aromatic pitch fraction and a solvating solvent; (b) maintaining the solvating solvent in a liquid state in the presence of the solvating solvent. Under conditions to promote the formation of larger heavy aromatic molecules, including sufficient pressure to
Thermal soaking the heavy aromatic pitch fraction while retaining sufficient solvent in the pitch fraction to produce a solvated mesophase pitch; and (c) the greater than formed in thermal soaking Solvating a heavy aromatic molecule, and recovering the solvated mesophase pitch containing a sufficient portion of the solvating solvent to solvate the solvated mesophase pitch. Of manufacturing a patterned mesophase pitch. 2. The step (a) and the step (b) are combined,
The method of claim 1 wherein the steps are performed in the presence of a sufficient amount of solvating solvent such that these steps occur simultaneously. 3. (a) heat soaking an aromatic raw material to obtain an isotropic heat soaked pitch containing a heavy pitch fraction; (b) the isotropic heat soaked pitch; Extracting and separating the heavy pitch fraction with a suitable solvent, (c) combining the heavy aromatic pitch fraction with a solvating solvent, (d) the heavy pitch fraction with In the presence of a solvating solvent, solvating under conditions to promote the formation of a larger heavy aromatic molecule that includes sufficient pressure to maintain the solvating solvent in a liquid state. Heat soaking the heavy pitch fraction while retaining sufficient solvent in the pitch fraction to produce a defined mesophase pitch; and (e) the heavy fraction. The solvated mesophase pitch containing the larger heavy aromatic molecules and a sufficient portion of the solvated solvent to solvate the solvated mesophase pitch produced by thermal soaking. A method of making a heavy solvated mesophase pitch comprising the step of recovering. 4. The heat soaking conditions to promote the formation of larger heavy aromatic molecules include the heavy aromatic pitch fraction at a temperature in the range of 360-520 ° C. and 14.
4. A method according to claim 1 or 3 comprising subjecting to a pressure in the range of 7 to 1000 psia for 5 minutes to 24 hours. 5. The temperature of the heat soaking is 380 to 460.
The method according to claim 4, which is in the range of ° C. 6. The step (c) and the step (d) are combined,
The method of claim 3, wherein the steps are carried out in the presence of a sufficient amount of solvating solvent such that these steps occur simultaneously. 7. The solvating solvent is an aromatic organic solvent having a solubility parameter (δ) in the range of 7.0 to 11.5, and a solvent having a structure containing 1 to 4 aromatic rings,
And one or more solvents selected from the group consisting of solvents having a structure containing 1 to 4 aromatic rings together with 1 to 3 hydroaromatic rings, and optionally 1 or more C _{1 to} C ₄ 3. An alkyl group which may be substituted with an alkyl substituent.
The method according to any one of 3 and 6. 8. The solvating solvent is benzene, xylene,
8. One or more solvents selected from the group consisting of anthracene, phenanthrene, chrysene, pyrene, tetralin, naphthalene, and natural aromatic distillates obtained from petroleum aromatics, coal tar and ethylene tar.
The described method. 9. The method according to claim 2 or 3, wherein the amount of the solvent solvent is in the range of 0.25 to 5.0 parts by weight of solvent with respect to 1 part by weight of pitch. 10. The solvating solvent is from 0.05 to 1 part by weight of the pitch during thermal soaking.
The method of claim 1 present in an amount of 5.0 parts by weight. 11. Recovery of the larger heavy aromatic molecule comprises:
The method of claim 1 achieved by solvent extraction. 12. The conditions for separating the larger heavy aromatic molecule are as follows: the larger heavy aromatic molecule is an extraction solvent, and the solvent is 0.25-5. Solvent to pitch ratio in the range of 0 parts by weight, 14.7-1000.
Contact at a pressure of psia and a temperature of 200 to 520 ° C.,
12. The method of claim 11, comprising forming a liquid extraction phase and a solvated residual phase, the solvated residual phase containing a desired heavy aromatic molecule. 13. The extraction solvent is an aromatic organic solvent having a solubility parameter (δ) in the range of 7.0 to 11.5, and has a structure containing 1 to 4 aromatic rings,
And one or more solvents selected from the group consisting of solvents having a structure containing 1 to 4 aromatic rings together with 1 to 3 hydroaromatic rings, and optionally 1 or more C _{1 to} C ₄ 13. The method of claim 12, optionally substituted with an alkyl substituent. 14. The extraction solvent is selected from the group consisting of benzene, xylene, anthracene, phenanthrene, chrysene, pyrene, tetralin, naphthalene, and natural aromatic distillates obtained from petroleum aromatics, coal tar and ethylene tar. 14. One or more solvents that are
The described method. 15. The method according to claim 2 or 6, wherein the method is carried out at a temperature in the range of 360 to 520 ° C. and a pressure in the range of 14.7 to 1000 psia. 16. The method of claim 3 wherein the solvating solvent used in the thermal soaking step (c) is a different solvent than that used in the extraction and separation step (b). 17. The solvating solvent used in the step (c) is a solvent having a higher boiling point than the solvent used in the step (b), and after the addition of the higher boiling point solvating solvent, the step ( 17. The method of claim 16, wherein the lower boiling point solvent of b) is allowed to evaporate.