JPH0245673B2 - - Google Patents

Description

[Detailed description of the invention]

<<Industrial Application Field>> The present invention relates to a raw material for producing optically anisotropic pits using residual oil from a catalytic cracker. More specifically, the present invention relates to a raw material for efficiently producing optically anisotropic pitches having a low softening point for producing carbon products. <<Prior Art>> Catalytic cracking has traditionally been used in the petroleum and petrochemical industries to convert light oil fractions containing aromatic naphthenic and paraffinic hydrocarbons into lighter and more useful products. A method using a reaction is used. Although various important light fractions can be obtained through this process, the residual oil produced as a by-product from catalytic cracking equipment is not fully utilized, and therefore, the value of this residual oil is limited. It was hot. Focusing on the low cost of catalytic cracker residual oil, in recent years it has been used to produce various high-performance carbon products produced by thermal decomposition of organic matter, such as carbon fibers, carbon films, carbon ribbons, etc. Attempts are being made to use it as a raw material for carbon sheets and the like. In particular, high-performance carbon fiber with high strength and elastic modulus is extremely excellent as a material for high-performance composite materials, and despite its high manufacturing cost, its demand continues to increase. It is important to develop inexpensive raw materials and manufacturing methods to reduce manufacturing costs. From this point of view, the production of carbon fibers from inexpensive carbonaceous pitches, which has been developed in recent years, has been attracting attention, and the present invention also belongs to this field. Conventionally, many carbonaceous pitches and tars are converted into optically anisotropic phases through thermal decomposition polycondensation reactions and become liquid crystal substances, and carbon fibers produced from optically anisotropic pitches thus converted are , high modulus, high strength, and is known to be an extremely high performance carbon fiber (US Pat. No. 4,005,183). Along with this, much research has been conducted on the production of optically anisotropic pitches necessary for producing high-performance carbon fibers, and several methods have already been disclosed (for example, Japanese Patent Publication No. 49-8634 (Japanese Patent Application Laid-open No. 118028/1983, Japanese Patent Application Laid-open No. 54-55625, and Japanese Patent Application Laid-open No. 56-167788). However, in each case, these conventional methods produce homogeneous, low softening point, optically anisotropic pitches suitable for producing high-performance carbon fiber products, especially high-performance carbon fibers, at low cost and in large quantities. Moreover, it has the disadvantage that it cannot be stably provided. The present inventors conducted various studies on the composition of optically anisotropic pitches in order to eliminate such drawbacks of the conventional methods, and as a result, the optically anisotropic pits are composed of molecules with a developed layered structure of condensed polycyclic aromatics. Although there are many types of pitches with good orientation, we found that in reality, there are a variety of them, and among them, those with a low softening point and suitable for producing homogeneous carbon fibers have a specific chemical structure and composition. . That is, in the optically anisotropic pitch, not only the structure and molecular weight of the n-heptane soluble component (hereinafter referred to as "O" component) and the n-heptane insoluble and benzene soluble component (hereinafter referred to as "A" component), These contents are extremely important for the overall properties of the optically anisotropic pitch, and furthermore, parts other than the "O" component and "A" component are benzene-insoluble but quinoline-soluble components. (hereinafter referred to as "B" component) and the quinoline-insoluble component (hereinafter referred to as "C" component),
``O'', ``A'', ``B'', and ``C'' components should be balanced to have substantially homogeneous and extremely excellent properties as an optically anisotropic pitch for producing high-performance carbon materials. (Patent Application No. 55-162972). Furthermore, as a result of research into the relationship between the characteristics of optically anisotropic pitch and the characteristics of raw materials, it was found that the presence of aromatic oil and resin components are important for good raw materials (patent application). (Sho 56-11124). Based on these findings, in order to efficiently produce optically anisotropic pits with excellent properties using low-cost catalytic cracker residual oil as a raw material, it is necessary to incorporate low-molecular-weight aromatic compounds together with the residual oil in the raw material. The present invention was achieved based on the discovery that it is preferable for the components to be contained in appropriate amounts. <<Problems to be Solved by the Invention>> Therefore, the first object of the present invention is to produce optically anisotropic pitches having excellent properties necessary for manufacturing high-performance carbon products such as carbon fibers at a low cost. The goal is to provide raw materials for efficient production. The second object of the present invention is to provide an optically anisotropic material with excellent properties that is a precursor material for efficiently producing high value-added carbon products by effectively utilizing catalytic cracker residual oil. An object of the present invention is to provide a manufacturing method for manufacturing pitchi. ≪Means for Solving the Problems≫ The above-mentioned objects of the present invention are to reduce the residual oil of catalytic cracking equipment from about 50% by weight to about 87% by weight with a boiling point of about 400°C or higher.
and the aromatic carbon fraction fa is 0.4 or more and about 200
An optically different material comprising about 13% to about 50% by weight of a hydrocarbon fraction having a boiling point of from about 540°C to about 400°C, and 90% by weight or more of a component having a boiling point of about 540°C or less. This was achieved by using raw materials for producing directional pitches. In the present invention, catalytic cracking refers to kerosene fraction, gas oil fraction, and other heavy oil fractions, especially those with a boiling point of about 300°C.
This refers to the cracking and conversion of straight-run gas oil, etc., which is between about It refers to residual oil whose main component is hydrocarbon components with a temperature of 400°C or higher, and is obtained by distilling off components with a boiling point of 400°C or lower by distillation after catalytic cracking. However, when taking this out from the catalytic cracker, by selecting the cut point for distillation in the catalytic cracker between 200°C and 400°C, the catalytic cracker residue oil and the boiling point
It is also possible to take out the hydrocarbon fraction at 200°C to about 400°C mixed with it. Therefore, in this case, if the conditions described below regarding fa and content of the hydrocarbon fraction having a boiling point of about 200° C. to about 400° C. are satisfied, the above mixture can be used as a raw material for the present invention. Generally, catalytic cracker residual oil contains only a small amount of components with a molecular weight of about 1000 or more, but if it contains 50% by weight or more of such components, it is preferable to remove them. Further, the catalytic cracker residual oil contains trace amounts of solids such as fine powder of cracking catalyst, but it is preferable to remove these solids to 0.01% by weight or less. JP-A-56-167788 discloses a method for producing optically anisotropic pitch, which comprises removing a fraction having a boiling point of about 400°C or less from the catalytic cracker residual oil and then heat-treating it. has been done. That is,
It is preferable that the raw material for the optically anisotropic pitch in this invention does not contain any fraction below about 400°C. However, the raw materials used in the present invention include not only catalytic cracker residue oil with a boiling point of about 400°C or higher, but also
Preferably, a fraction having a boiling point of about 200°C to about 400°C is present. The reason for this remarkable difference between the invention disclosed in Japanese Patent Application Laid-open No. 56-167733 and the present invention is that the present invention is disclosed in Japanese Patent Application No. 55-162972 and Japanese Patent Application No. 56 This is because it was made based on the knowledge obtained in the invention disclosed in No.-11124. That is, the method disclosed in JP-A-56-167788 is different from the idea of the present application, and the method disclosed in JP-A-56-167788 is different from the idea of the present application. Regardless of the balance, this method is suitable as a method for producing optically anisotropic pitches containing a large amount of relatively high molecular weight optically anisotropic pitches obtained by removing as much low molecular weight substances as possible by solvent extraction. On the other hand, both inventions are fundamentally different in that the present invention emphasizes the balance of each component "O", "A", "B", and "C" in the optically anisotropic pitch. different. Therefore, in the case of the method disclosed in JP-A-56-167788,
Since the produced optically anisotropic pitch tends to contain components with high softening points, a complicated process of removing them with a solvent is required, whereas in the case of the present invention, such a complicated process is not necessary at all. The entire manufacturing process is greatly simplified. <<Function>> Boiling point contained in the raw material of the present invention: about 200°C to about 400°C
The fraction at ℃ contains a large amount of low-molecular aromatic hydrocarbons, and their presence is due to the formation of the above-mentioned "O", "A", "B", and "C" components in a short time reaction. It has the function of reducing the softening point while maintaining the orientation and homogeneity of the optically anisotropic pitch product. This is based on the fact that there is a causal relationship between the orientation, homogeneity (or compatibility), and softening point of the optically anisotropic pitch and the molecular structure of the pitch. First, the orientation of the optically anisotropic pitch is related to the planar structure of the molecules and the fluidity of the liquid at a certain temperature. In other words, for highly oriented pitch, the planar structure of the pitch molecules is sufficiently large, and the liquid fluidity necessary for rearranging the plane of the molecules in the fiber axis direction during melt spinning is required. is a necessary condition. Here, the planar structure of the molecule is determined by the size of the fused polycyclic aromatic, the number of naphthene rings, the number and length of side chains, etc., so all of the carbon atoms forming the aromatic structure contained in the molecule are It can be evaluated by fa, which is the ratio to carbon atoms. fa in the present invention is determined by Kato's method (Fuel Association 55 , 244) from the results of infrared absorption spectrum measurement.
(1976)), but in general, the larger the fused ring aromatic, the fewer the number of naphthenic rings, the fewer the number of paraffin side chains, and the shorter the length of the side chain, the greater the fa. Larger and generally fa
The larger the value, the greater the planar structure of the molecule. From this, it is understood that it is preferable for the raw material to contain a large amount of aromatic hydrocarbons, since this increases the planar structure of the optically anisotropic pitch molecule that is the product. If the planar structure of the molecules improves, the orientation of the optically anisotropic pitch will increase, making it easier for molecules to align in the fiber axis direction during spinning, making it easier to produce high-performance carbon fibers. Therefore, there is no need to increase the molecular weight of the optically anisotropic Pitch molecule more than necessary through excessive reaction to increase the content of the optically anisotropic phase and its orientation. That is, even if the molecular weight of the optically anisotropic pitch is lowered, the performance of the carbon fiber is not only maintained sufficiently, but also the advantages of ease of spinning become greater. This is because containing a large amount of relatively low-molecular-weight aromatic hydrocarbons in the raw material increases the planar structure of the optically anisotropic pitch molecules and simultaneously decreases the average molecular weight. This means that the softening point of the pitch is lowered, and therefore, the reaction can be carried out sufficiently to increase the homogeneity of the optically anisotropic pitch. This is the reason why the raw material of the present invention actively contains a hydrocarbon fraction having an fa of 0.4 or more and a boiling point of about 200°C to about 400°C. Even if there is too much distillate with a boiling point of about 200℃ to about 400℃,
"O" in the optically anisotropic pitch which is the product,
It becomes difficult to balance the components "A", "B", and "C". Therefore, it is preferable that the fraction between about 200°C and above and about 400°C is contained in an amount of about 13% to about 50% by weight, preferably about 15% to about 40% by weight. The content can be easily adjusted by adding the above-mentioned fraction to the catalytic cracker residual oil, and the cut point of distillation in the catalytic cracker can be adjusted to 200°C to 400°C.
This can be easily carried out by leaving the cracked gas oil fraction remaining. In addition to the cracked gas oil fraction from the catalytic cracker, the fractions include distillate obtained from thermal crackers, such as naphtha steam crackers, thermal polycondensation reactors, etc., and coal liquefaction equipment. Decomposed light oil etc. can be used.
In addition, a hydrocarbon component having a small molecular weight and a low boiling point undergoes a slow thermal polycondensation reaction, reducing the final pitch yield. Taking such phenomena into consideration comprehensively, in carrying out the present invention, the boiling point and fa of the hydrocarbon fraction to be used are specified. In this way, embodiments of the prepared feedstock have a boiling point of about
The fa of the hydrocarbon fraction below 400℃ is 0.4 or more,
Initial boiling point is about 200℃ or higher, about 15% to about 40% by weight
The distillation point is about 400°C, and the 90% distillation point is about 540°C or less. Those whose 90% by weight distillation point rises above about 540°C are undesirable because they contain components with extremely high molecular weights and make the softening point of the produced pitch abnormally high. The optically anisotropic pitch produced using the specified raw material obtained in this way has a softening point despite the content of the optically anisotropic phase being as high as 90% to 100% by volume. It has a low temperature of about 230℃ to 320℃, making it suitable for manufacturing carbon products. In particular, when carbon fibers are produced by melt spinning, the spinning temperature can be lowered, and the process has good spinnability, which is extremely convenient for producing high-performance carbon fibers. When the raw material of the present invention is used, the optically anisotropic pitch produced by any production method has a good balance of "O", "A", "B", and "C" components, and has low softening. You can get points. That is, for example,
A method using a catalyst such as aluminum chloride may be used, or a method using a thermal decomposition polycondensation reaction without using a catalyst,
If necessary, a subsequent solvent extraction method may be used, and the reaction may be carried out with stirring or bubbling inert gas as necessary, or the reaction may be carried out under pressure or reduced pressure. You can also Here, the pyrolysis polycondensation reaction refers to a reaction in which the pyrolysis reaction of hydrocarbons in the raw material and the polycondensation reaction proceed in parallel as main reactions to produce optically anisotropic pitches. This is thought to be due to the development of a planar structure of polycyclic fused aromatics due to paraffin chain scission, dehydrogenation, ring closure, and polycondensation. The temperature of the thermal decomposition polycondensation reaction for producing optically anisotropic pitches is about 380°C to about 460°C, preferably about 400°C, in order to complete the reaction in a short time of about 1 to 3 hours. ~about 440℃. If the temperature is too low, the reaction will take a long time, and if the temperature is too high, the softening point of the optically anisotropic pitch produced will become high, which is not preferable. When using the raw material of the present invention, approximately 2Kg/cm ² ~
It is preferable to carry out thermal decomposition polycondensation under a pressure of about 50 kg/cm ² and then heat under an inert gas flow to remove low molecular weight substances. The process of producing optically anisotropic pitches by these methods is further connected to the process of separating the produced optically anisotropic pitches, as disclosed in Japanese Patent Application No. 1983-
As in the case of No. 11124, the present invention is also extremely effective. In other words, this is a method for separating the optically anisotropic pitch produced during the process of pyrolysis polycondensation reaction. Since the raw material of the present invention has a large content of relatively low molecular weight aromatic components, it also contributes to preventing the optically anisotropic pitch produced by the reaction from becoming larger than necessary. Furthermore, using the method of separating the optically anisotropic pitches generated during the process of the pyrolysis polycondensation reaction means that the generated optically anisotropic pitches are kept at a high temperature until the end of the reaction. In order to avoid this, it is possible to prevent the adverse effect of the molecular weight becoming larger than necessary due to the polycondensation reaction of optically anisotropic pitches proceeding more than necessary, and to obtain optically anisotropic pitches with a low softening point. This is even more convenient. In order to separate the optically anisotropic pitches generated during the process of pyrolysis polycondensation reaction, thermal decomposition should be carried out when the optically anisotropic pitches generated reach approximately 20% to 80% by volume. While the polycondensation reaction is stopped and the reaction tank is left virtually stationary, the temperature is set at a temperature at which the thermal decomposition polycondensation reaction is difficult to occur and the fluidity of the pitch fluid is maintained sufficiently, that is, approximately 350°C to Approximately 400℃,
Preferably, by maintaining the temperature at about 360°C to about 390°C, the optically anisotropic phase portion with a higher density in the lower layer grows and matures as one continuous phase and is deposited, and this is deposited in the lower layer, which is an isotropic phase with a lower density. It is sufficient to separate it from the phase containing a large amount of sex pitch. If the above-mentioned temperature range is adopted, this separation step can be completed in 1 to 3 hours, but if a longer time is acceptable, it is of course possible to select a lower temperature range. In the present invention, furthermore,
As disclosed in No. 57-052731 (Japanese Patent Publication No. 62-38400), by providing a reaction zone and a standing zone in one reaction tank, it has the function of a reaction tank and a sedimentation separation tank at the same time. It is also possible to continue both the pyrolysis polycondensation reaction step and the separation step of the produced optically anisotropic pitch. That is, by making the upper part of the reaction tank a stirred reaction area and the lower part of the reaction tank a substantially static area, if the raw material of the present invention is continuously injected from the upper part of the reaction tank, the lower part of the reaction tank is lowered. Optically anisotropic pitches with excellent softening point properties can be continuously extracted. Further, the above-described pit partially containing optically anisotropic pitch is subjected to a centrifugation operation in its molten state to efficiently and continuously separate the optically anisotropic pitch which is a phase with a higher specific gravity. You can also do it. As the centrifugation operation conditions, a temperature of about 260° C. to about 390° C., preferably about 330° C. to about 360° C., and a centrifugal force acceleration of about 10,000 G or less, preferably about 50 G to about 3,000 G can be adopted. . However, G here is gravitational acceleration. ≪Effect of the invention≫ When the raw material of the present invention is used, JP-A-56-
Not only can the distillation operation under severe conditions as disclosed in Publication No. 167788 be omitted, but the viscosity of the reactant is relatively low due to the large amount of low molecular weight aromatic hydrocarbon components, and the pipe transfer and stirring of raw materials is sufficient. Not only is it easy to carry out, but also the removal of solid matter is easy, and the reaction time required to produce optically anisotropic pitches can be shortened compared to conventional methods. Furthermore, the optically anisotropic pitch produced using the raw material of the present invention contains an optically anisotropic phase of 90% to 100% by volume, is substantially homogeneous, and has an extremely low softening point. Has excellent properties. Therefore, complicated and costly steps such as high-temperature filtration of infusible substances, extraction of solvent, and removal of catalyst, which are required in the conventional method, are not required. Regarding melt-spinning of carbon fibers, the spinning temperature (the maximum temperature that must be applied to the pitch during the spinning process) can be within the range of approximately 290℃ to approximately 360℃, which eliminates problems such as the generation of decomposed gas. The advantages of the present invention from an industrial perspective are that not only is there no problem, but high-performance yarn can be easily spun without yarn breakage, and there is less energy loss due to heating. It is enormous. Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. Example 1 Distillation in a catalytic cracker after catalytic cracking
℃, the initial boiling point is 204℃, the 25% by weight distillation point is 400℃, the 70% by weight distillation point is 450℃, and the 90% by weight distillation point is 510℃ (all of these temperatures are (This is the normal pressure equivalent value of the distillation temperature measured during vacuum distillation operation)
The distillation operation in the catalytic cracker is controlled so that the boiling point is 204℃~400℃ and the aromatic carbon fraction fa
A mixture was prepared consisting of 25% by weight of a hydrocarbon fraction with a boiling point of 0.43 and 75% by weight of a catalytic cracker residual oil with a boiling point of 400° C. or higher, and was used as a feedstock without further distillation. 400 grams of this raw material was placed in a 500 ml stainless steel reaction vessel, and a thermal decomposition polycondensation reaction was carried out at 430°C for 2 hours. During the reaction, nitrogen gas was passed through the surface of the liquid phase at a rate of 2/min as an inert gas, and the mixture was thoroughly stirred with a stirring blade. After the reaction, take 50 ml of the pitsuchi (hereinafter referred to as βRP) that remained in the container and have an optically anisotropic phase content (hereinafter referred to as AP%) of 10% by volume or more into a glass beaker, and place it in a matzuru in a nitrogen gas atmosphere. After standing in a furnace at about 380°C for 2 hours to separate the optically anisotropic phase, it was cooled to room temperature and solidified.
Next, the glass beaker was broken and separated into an upper layer containing a large amount of optically isotropic phase and a lower layer containing a large amount of optically anisotropic phase. The AP% of the lower optically anisotropic phase is
100%, softening point is 268℃, "O", "A",
The content of "B" and "C" is 11.7% by weight, respectively.
They were 28.6% by weight, 25.2% by weight, and 34.5% by weight.
10 grams of the optically anisotropic pitch obtained in this way was filled into a small spinning machine, and while the temperature was raised, nitrogen gas was added to the spinning machine.
It was pressurized to 100 mmHg, extruded through a nozzle with a diameter of 0.3 mm, and wound at a linear speed of 600 m/min with a bobbin installed at the bottom. The temperature at which the frequency of yarn breakage is the minimum was found in the spinning temperature range of about 330°C to about 370°C, and the frequency of yarn breakage at that temperature was evaluated. For comparison, similar experiments were conducted when the raw material was distilled to 400°C, that is, 100% catalytic cracker residual oil, and when the raw material was distilled to 450°C. We also compared the three. However, in the former comparison experiment, the pyrolysis polycondensation reaction time was set to 2.5 hours. Tables 1 and 2 show the comparison results. As is clear from these tables, when the raw materials of the present invention are used, they are quinoline-insoluble components.
Since an optically anisotropic pitch with a low content of the "C" component was obtained, the softening point of the optically anisotropic pitch was low and the frequency of thread breakage was reduced, which was extremely good.

【table】

[Table] Example 2 As a raw material for the present invention, the initial boiling point was 204°C and 35% by weight.
The distillation point is 400°C, the 90% by weight distillation point is 534°C (these temperatures are normal pressure equivalent values, as in Example 1), and the distillate at 400°C is A mixture of 35% by weight of a hydrocarbon fraction with a boiling point of 204°C to 400°C with an aromatic carbon fraction fa of 0.56 and 65% by weight of catalytic cracker residual oil with a boiling point of 400°C or higher is used as a raw material without further distillation. Pitch was obtained in the same manner as in Example 1, except that it was used. The obtained pitches were as shown in Table 4.
The optically anisotropic phase was 100% (AP% in the table is 100) and the softening point was low, and the spinning properties of the carbonaceous pitch were also extremely excellent.

【table】

[Table] Example 3 The raw material of the present invention has an initial boiling point of 204°C, a 18% by weight distillation point of 400°C, and a 90% by weight distillation point of 527°C (these temperatures are the same as in Example 1). The distillation operation in the catalytic cracker is controlled so that the distillation operation in the catalytic cracking apparatus is controlled so that 18 weight hydrocarbon fractions with a boiling point of 204°C to 400°C and an aromatic carbon fraction fa of 0.57 are obtained. % and 82% by weight of catalytic cracker residual oil with a boiling point of 400°C or higher was prepared in the same manner as in Example 1, except that it was used as a raw material without further distillation. A directional pitch was obtained.

【table】

[Table] As is clear from the results in Table 6, the raw material of the present invention containing 18% by weight of hydrocarbon fraction below 400°C is
100% optically anisotropic phase due to thermal decomposition polycondensation reaction
It is possible to provide a carbonaceous pitch with a low softening point, and the spinning properties of the carbonaceous pitch are also significantly superior compared to when raw materials from which hydrocarbon fractions below 400°C are removed are used. Something has been proven.

Claims (1)

[Claims] 1. About 50% to about 87% by weight of residual oil from a catalytic cracker with a boiling point of about 400°C or higher and an aromatic carbon fraction fa.
0.4 or more and consists of about 13% to about 50% by weight of a hydrocarbon fraction having a boiling point of about 200°C to about 400°C, and 90% by weight or more of a component having a boiling point of about 540°C or less A raw material for producing an optically anisotropic pitch characterized by: 2 The residual oil from the catalytic cracker with a boiling point of about 400°C or higher is about 60% to about 85% by weight, and the boiling point is about 200°C to about 85% by weight.
Approximately 15% by weight of hydrocarbon fraction with a boiling point of 400°C
~40% by weight of a raw material for producing an optically anisotropic pitch according to claim 1. 3. A raw material for producing the optically anisotropic pitch according to claim 1 or 2, which has an aromatic carbon fraction fa of 0.5 or more.