WO2007126121A1

WO2007126121A1 - Method for processing plastic and apparatus therefor

Info

Publication number: WO2007126121A1
Application number: PCT/JP2007/059406
Authority: WO
Inventors: Joichi Takenaka; Kunio Miyazawa
Original assignee: Jfe Chemical Corporation
Priority date: 2006-04-27
Filing date: 2007-04-25
Publication date: 2007-11-08

Abstract

Disclosed is a method for processing a plastic, which comprises a step for dissolving a plastic having a benzene ring into a solvent which is poorly soluble in water, a step for hydrocracking the thus-obtained solution of the plastic having a benzene ring, a step for fractionating the product obtained in the hydrocracking step, and a step for thermally decomposing at least a part of the heavy distillate obtained in the fractionating step. Benzenes, which are extremely useful in chemical industries and pharmaceutical industries, can be produced by this method by using a waste plastic which contains at least a benzene ring-containing plastic, as a raw material. In addition, other by-produced cracked oils can be effectively utilized.

Description

Plastic processing method and apparatus

TECHNICAL FIELD The present invention relates to a method and apparatus for treating a plastic having a benzene ring. In particular, waste plastics that contain at least plastics with a benzene ring.

As a raw material, it is related to plastic processing methods and equipment for obtaining benzenes that are extremely useful in the chemical and pharmaceutical industries, and at the same time, effectively using other by-product cracked oils.

Background art

Technologies for decomposing benzene ring-containing plastics such as polystyrene to obtain benzene or benzene derivatives (hereinafter also referred to as benzenes) include technologies based on thermal decomposition (thermal decomposition method), or thermal decomposition in a hydrogen atmosphere. Technology (hydrocracking). As an example of the thermal decomposition method, in Japanese Patent Application Laid-Open No. 9-13048, waste plastic containing expanded polystyrene (polystyrene) is thermally decomposed to obtain benzene such as styrene. , 'However, it is difficult to strictly control the decomposition reaction in the thermal decomposition method. Therefore, if expanded polystyrene is used as the raw material, alkanes such as ethane, ethylene, alkenes, although benzene, toluene, and xylene are less powerful. As a by-product is produced, carbon solids called so-called coatus are produced as much as 15% by mass. The yield of liquid substances containing is about 80 mass. /. It will be about. Moreover, since liquid substances contain a lot of substances other than benzenes, the actual yield of benzenes is 80 mass. /. It is estimated that the yield of benzens is less than 70% by mass in the case of hydrocracking, where the amount of coatas produced is as low as 5% by mass.

That is, in the thermal decomposition method, even if it is assumed that the main chain of polystyrene is decomposed into a gaseous substance, about 20% by mass of the total benzene ring of polystyrene is a by-product other than benzenes. It is clear from the material balance that chemical recycling of the benzene ring ^ / cannot be said to be highly efficient.

On the other hand, as an example of hydrocracking method, Hokkaido Industrial Development Laboratory Report No. 15, page 79 (1 977) discloses a hydrocracking method of polystyrene waste in the presence of zinc chloride catalyst. . However, the yield of benzenes (alkylbenzenes) is 70 mass. / Stops at ₀ .

In JP-A-2003-321682, a liquid monocyclic or polycyclic aromatic compound containing waste plastic that has been liquefied by heating is hydrogenated and decomposed, and the resulting reaction product is used as a cyclization catalyst. Benzenes are obtained by reaction in the presence. These hydrocracking methods increase the yield of benzenes compared to the pyrolysis method.

However, in any of the above decomposition methods, waste plastics usually contain chlorine-containing polymers such as polychlorinated butyl and chlorine compounds derived from sodium chloride. Even so, the heavy fraction contains various chlorine compounds such as by-product chlorine compounds, so there is no use for the heavy fraction and it is difficult to dispose of it.

¾ There was.

The present invention has been made in view of such a point, and it is possible to obtain benzenes in a high yield from a plastic having a benzene ring and to effectively use other by-product decomposition oil. It is an object of the present invention to provide a plastic processing method and apparatus. Disclosure of the invention

That is, the present invention includes a step of dissolving a plastic having a benzene ring in a solvent hardly soluble in water, a step of hydrocracking the obtained plastic solution having a benzene ring, and a product of the hydrocracking step. A process for treating plastics, and a process for thermally decomposing at least a part of the heavy fraction of the fractionation process.

In this plastic processing method, it is preferable to further include a dechlorination step before the fractionation step. Among these, the dechlorination is more preferably centrifugal separation or water washing.

In any of the plastic processing methods described above, it is preferable that the thermal decomposition is at least a partial coating of the heavy fraction.

Alternatively, it is preferable that the pyrolysis is carried out by charging at least a part of the heavy fraction into a coke oven and coking with coal, wherein ffl of the coke oven charge is More preferably, at least a portion of the heavy fraction is mixed with the coal. Further, it is more preferable that the temperature at which at least a part of the heavy fraction is mixed with the coal is 20 to 100 ° C. Further, it is more preferable to use a molded mixture of at least a part of the heavy fraction described in this paragraph and the coal. .

Alternatively, it is more preferable that the pyrolysis is carried out in a step of reforming the coal by mixing at least a part of the heavy fraction with the coal and heating it. ..

Furthermore, in any of the plastic processing methods described above, it is preferable that the thermal decomposition is performed at 400 to 600 ° C. .

In any of the above plastic processing methods, the boiling point of the heavy fraction is It is preferably 3 30 ° C or higher.

In general, in any of the above-described methods for treating plastics, it is preferable that the plastics have a benzene ring and are a mixture of a plastic having a benzene ring and another plastic.

In any of the above plastic processing methods, the plastic having a benzene ring is preferably a waste plastic containing at least a plastic having a benzene ring.

Furthermore, in any of the above-described methods for treating plastics, it is preferable that the plastics have a benzene ring and the plastic contains at least polystyrene.

In any of the above plastic processing methods, the solvent is preferably at least one selected from the group consisting of coal tar and coal tar distillation fraction.

Furthermore, in any of the plastic processing methods described above, the product of the hydrocracking step is preferably a benzene.

The present invention also includes a dissolution tank equipped with a stirrer and a heating device up to 250 ° C., a pressure reaction vessel capable of withstanding 120 kg / cm ² G at 500 ° C., a fractionator, and It is also a plastic processing equipment equipped with a pyrolysis tank that is resistant to hydrogen chloride and chlorine gas.

The plastic processing apparatus preferably further includes either a centrifuge or a separator equipped with a heating device and a water injection device up to 25 ° C. before the fractionator. .

Furthermore, in any of the plastic processing apparatuses described above, the pyrolysis tank is at least one selected from the group consisting of a coke oven, a coker, and a coal reforming furnace. It is preferable. Further, the present invention provides a hydrolyzing process in which a plastic and a solvent are mixed and heated to dissolve the plastic, and the plastic solution obtained in the dissolving process is hydrocracked in the presence of a catalyst. A hydrocracking step for carrying out the reaction, a distilling step for distilling the hydrocracking reaction product produced in the hydrocracking step to obtain a heavy fraction, and a heavy fraction obtained in the distillation step It is also a plastic processing method characterized by having a pyrolysis step of thermally decomposing. Brief Description of Drawings

FIG. 1 is a schematic explanatory view showing an embodiment of the plastic processing apparatus of the present invention. FIG. 2 is a schematic explanatory view showing one embodiment of a manufacturing apparatus for another plastic processing apparatus according to the present invention.

FIG. 3 is a schematic explanatory view showing an embodiment of a manufacturing apparatus for another plastic processing apparatus according to the present invention.

FIG. 4 is a schematic explanatory view showing an embodiment of a manufacturing apparatus for another plastic processing apparatus according to the present invention.

FIG. 5 is a schematic explanatory view showing an embodiment of a manufacturing apparatus for another plastic processing apparatus according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

In order to solve the above-mentioned problems, the present inventors have improved the hydrocracking method and effective use of cracked oil produced as a by-product, particularly heavy fractions, for a mixed plastic having a benzene ring-containing plastic. It was investigated. As a result, the heavy fraction is thermally decomposed, We found a method that can convert it into chlorides such as Zen, Kotas and hydrogen chloride. However, it was found that these conversion products can be recovered individually, so that the yield of benzenes can be improved and the heavy fraction can be effectively used.

In other words, if a mild hydrogenation angle reaction is performed, the heavy fraction in cracked oil becomes a liquid with abundant hydrogen content and low viscosity, and can be easily pyrolyzed by a simple process. Furthermore, it is possible to modify poor coal with compounds that easily donate hydrogen, that is, hydrophenanthrene and its derivatives, hydroanthracene and its derivatives, and hydropyrene and its derivatives. In addition, it is possible to increase the recovery of benzenes by coking heavy fractions with a coker, and to obtain the knowledge that the resulting coke can be properly disposed of in an integrated steelworks sintering machine, coke oven, or blast furnace. It was. The method of the present invention is also optimal for chemical recycling of waste plastics with a large amount of benzene recovered.

The present invention has been made based on these findings.

The plastic having a benzene ring of the present invention includes a benzene ring as a part of the polymer structure, and, as is apparent from the gist of the present invention, a ring-closing reaction (such as heating and z or hydrogenolysis reaction). Also included are polymers that can form benzene rings as part of the polymer structure by cyclization reactions) and Z or cleavage reactions. The benzene ring contained may be contained in the polymer main chain or in the polymer side chain. The benzene ring may have a substituent. Examples of polymers that contain a benzene ring as part of the polymer structure include polystyrenes, polyethylene terephthalates, polycarbonates, phenol resins, xylene resins, ABS resins, polysulfones, and polyethylene. Examples include lenoxides.

Furthermore, according to the method of the present invention, the heavy fraction obtained can be effectively used. The plastic having a benzene ring may be a mixture of a plastic having a benzene ring and another plastic.

Further, the plastic having a benzene ring applicable to the present invention may be an unused plastic or a plastic after being used for some purpose. From the perspective of resource reuse, it is preferable to use plastic that has been used and discarded (hereinafter also referred to as waste plastic). That is, in the present invention, as the plastic having the benzene ring, a plastic that contains at least a plastic having a benzene ring can be suitably used.

Any of the plastics having the benzene ring is more preferably a plastic containing at least polystyrene. As the benzene ring-containing plastic, in addition to industrial waste, a mixture of polyethylene and polypropylene can be used. In addition, waste plastics well known as municipal waste often contain chlorine-containing plastics such as polyvinyl chloride and polyvinylidene chloride, but such mixed plastics may also be used. The typical composition (% by weight) of waste plastic is as follows: polyethylene: 20 to 40%, polypropylene: 10 to 20%, polystyrene: 10 to 40% polyethylene terephthalate: 5 to 10 %, Polysalt {Vinolein resin. Polyvinylidene chloride resin: 1 to 10%, and other impurities: 1 to 10%. No special adjustment of the particle size of the benzene ring-containing plastic is required, but it is desirable to use crude oil because the dissolution time is shortened. Moreover, if it is a small amount, it may contain a thermosetting resin or paper.

瞧? Process]

The solvent is hardly soluble in water and contains a benzene ring-containing plastic or this. It is not particularly limited as long as it can dissolve or fluidize the mixed plastic (hereinafter also referred to as plastic or mixed plastic). The water-insoluble solvent referred to in the present application includes water-insoluble solvents. The solvent is preferably a monocyclic, bicyclic or tricyclic aromatic compound and various derivatives thereof, or a mixture thereof from the viewpoint of compatibility with plastics. In particular, each fraction of coal tar can also be used to fluidize thermosetting resins and papers, making it possible to pump up waste plastic containing benzene ring-containing plastic into the hydrocracking reactor. Is preferred. For each coal tar fraction, coal tar (all fractions), creosote oil fractions produced in a coal tar distillation plant, anthracene oil fractions, etc. can be used. You may contain. The mixing ratio of the benzene ring-containing plastic or the mixed plastic containing it with respect to the solvent is preferably 5 parts by mass Z 95 5 parts by mass to 40 parts by mass / 60 parts by mass. 5 parts by mass / 9 As the treatment amount increases at 5 parts by mass or more, the economy improves. Further, 40 parts by mass or less of Z 60 parts by mass is more advantageous for fluidity.

Regarding the conditions for dissolving the plastic, it is preferable to dissolve it by heating to 150 ° C or higher. Heating to 150 ° C or higher is more economical because the plastic has a higher dissolution rate and can be dissolved in a smaller dissolution tank. However, from the point of view of operation, temperatures below about 400 ° C are sufficient. In addition, if the temperature exceeds 250 ° C., the light fraction will be volatilized significantly. In this case, it is desirable to perform the dissolution treatment in a sealed container.

In this process, when heat treatment is performed, if the waste plastic contains chlorine-containing plastics such as polychlorinated butyl, a decomposition reaction occurs in all or part of the chlorine-containing plastics, and chlorine compounds such as hydrogen chloride are also generated. It may occur.

[Hydrolysis process] In this step, the benzene ring-containing plastic solution obtained in the dissolution step is reacted with hydrogen to decompose the plastic (hereinafter also referred to as a hydrogenolysis reaction). In the hydrocracking reaction, the solvent may be decomposed at the same time. Even in this process, if waste plastic, which is a mixed plastic, contains chlorine-containing plastics such as polychlorinated butyl, all or part of the chlorine-containing plastic also undergoes a decomposition reaction, and chlorine compounds such as hydrogen chloride are also produced. May occur.

The hydrocracking reaction is preferably performed in the presence of a catalyst.

As the catalyst to be used, when the concentration of the chlorine compound is low, that is, in many cases using industrial waste plastic as a raw material, a Co—Mo, Ni—Mo, Ni—W catalyst, or iron Catalyst (iron oxide, iron sulfide, iron sulfate and its calcined product). These catalysts can be supported on a support such as alumina (A 1 ₂ 0 ₃ ), silica (S i 0 ₂ ), or zeolite if necessary.

On the other hand, when waste plastic such as municipal waste (general waste) is used as a raw material instead of industrial waste, it contains chlorine in the order of%, so the precious metal component of the catalyst deteriorates by forming chloride. End up. Therefore, in such a case, an iron-based catalyst that has catalytic performance even if it becomes a chloride is preferable. Typical examples of iron-based catalysts include iron ore and converter dust. When using with granular materials, it is usually the common particle size 0.;! ~ 10mm is enough. This catalyst may be used in any reaction mode such as a fluidized bed, a fixed bed, or a slurry bed.

The mixing ratio of plastic: solvent: catalyst supplied to the hydrocracking reactor is preferably 5: 94: 1 to 36:54:10 by mass ratio.

The catalyst may be added before the dissolution step.

The hydrocracking reaction may be carried out in either liquid phase or gas phase, and the reaction temperature is 300. About 500 ° C, preferably 400-450. About C, the pressure is about 1.0 to 2 p. 3 MPa (10 to 200 atmospheres), preferably 5.1 to 10. IMP a (50 to: LOO atmosphere).

According to the method of the present invention, examples of the reaction product in the hydrocracking step include benzenes such as benzene, toluene, xylene and ethylbenzene.

[Fractionation process].

In this step, the product obtained in the hydrocracking step is fractionated to obtain useful components such as benzenes and cracked oil. The product of the hydrocracking step may include the solvent used and its cracked product. More specifically, hydrogenated tar fractions (light fractions) corresponding to lighter gas fractions mainly composed of C3 to C4, benzene fractions, creosote oil and anthracene oil, etc. , And heavy fractions. This heavy fraction preferably has a boiling point of 330 ° C or higher.

[Pyrolysis process]

In this step, at least a part of the heavy fraction obtained by the above fractionation is pyrolyzed to further effectively use the heavy fraction. A preferable thermal decomposition temperature is 400 to 600 ° C. Note that this pyrolysis temperature is the temperature when passing through the region of 400 to 600 ° C, such as when charging directly into a coke oven or mixed with coal. It does not matter even if the temperature is higher after pyrolysis.

The various pyrolysis methods are described below.

(a) At least a part of the heavy fraction is converted into a powder and thermally decomposed.

'For example, at least a part of the heavy fraction can be charged together and pyrolyzed to obtain coatas, and at the same time, benzenes such as BTX (benzene, toluene, xylene) can be increased. it can. (b) At least a part of the heavy fraction is charged into a coke oven and pyrolyzed together with the coking of coal.

The method for charging the heavy fraction into the coke oven is not particularly limited. That is, the heavy fraction may be charged directly into a coke oven, or mixed with coal to be coked and charged together with the coal.

Moreover, when mixing a heavy fraction and coal, it is more preferable to shape | mold. The forming is possible, for example, by a method of producing bean charcoal. When the particle size of the coal is about 3 mm or less, the contact efficiency between the inorganic matter and the heavy fraction in the coal is improved, and the rate of formation of chloride is increased. There are no particular restrictions on the mixing temperature and molding temperature of the heavy fraction and coal, but 20-100 ° C is preferable, and 20-80 ° C is more preferable in terms of improving the fluidity of the heavy fraction. It is. When the temperature is 100 ° C or lower, it is easy to suppress the volatilization of components, and it is easy to maintain a good working environment.

In the case of forming, the coal has a higher density of coal particles, so the coking property is improved, that is, the coal is reformed. In addition, chlorine such as hydrogen chloride (HC 1) generated by thermal decomposition of heavy fractions during high-temperature dry distillation in the Kotas furnace is trapped by inorganic substances in the coal, for example, becoming stable chlorides. This means that most of the chlorine contained in the heavy fraction reacts with inorganic matter in the coal - to form a Na C l, KC 1, C a C l 2, stable chlorides such as Mg C 1 ₂ . For this reason, it is difficult to generate harmful substances that corrode equipment such as salt and hydrogen (HC 1) even at high temperature carbonization in a coke oven.

(c) At least a part of the heavy fraction is mixed with coal and heated to thermally decompose while reforming the coal.

'It is preferable to use inferior coal and / or non-coking coal as the coal. In addition, the degree of coalification (R.) of the inferior quality coal is R. <0.68. The degree of coalification (R.) of the non-slightly caking coal is 0.68 to 0.80. The degree of coalification is the ratio of reflected light when the coal is irradiated with light, and is measured according to JISM 8816.

Here, when waste plastic is used as the raw material plastic, the heavy fraction is enriched with chlorine, and as such, no use can be found. Therefore, in the present invention, the heat treatment is performed by mixing with the inferior coal that does not become the raw material for Kotas, or the non-slightly caking coal that does not become the raw material for Kotas alone. The heat treatment is preferably performed at 300 to 500 ° C, particularly 350 to 450 ° C. When the temperature is 300 ° C or higher, reforming is likely to occur, and when the temperature is 500 ° C or lower, the operation is advantageous. The atmosphere should be a nitrogen atmosphere or a reducing atmosphere, and the reaction pressure should be 0.1 to 15.2 MPa (1 to 150 atmospheres). In addition, a hydrogen atmosphere is preferable because the reforming effect is further improved. Even with this heat treatment, most of the chlorine contained in the heavy fraction reacts with the inorganic substances present in the poor coal and non-slightly caking coal, resulting in NaC l, KC 1, CaC l ₂ , Mg C 1 ₂ Forms stable chlorides. For this reason, it is difficult to generate harmful substances that corrode equipment such as hydrogen chloride (HC 1) even in high temperature distillation in a coke oven. Inferior coal and non-slightly caking coal react with the heavy fraction, and become coal (modified coal) of almost the same quality as coking coal for coke production. This makes it possible to effectively use inferior or non-coking coal.

In the present invention, it is preferable to further add a dechlorination step before the fractional distillation step. The dechlorination referred to in the present invention is to remove a chlorine compound from the product of the hydrocracking process. For this purpose, it is natural to remove the chlorine compound in the form of a molecule when removing it, and it is removed as a c 1 -ion and its counter ion. From the point of view, the molecule containing chlorine is missing. Including cases that can be seen. Specifically, gravity precipitation, hydrocyclone, centrifugation, or water washing by liquid-liquid extraction can be exemplified as the dechlorination method.

If the method of the present invention is mainly applied to the reuse of resources, that is, chemical recycling of waste plastics, waste plastics containing benzene ring-containing plastics are used as raw materials for this effort. Recommended. However, such waste plastics often contain chlorine-containing plastics such as polychlorinated butyl, and all or one of the chlorine-containing plastics is used in the above-described dissolution process and Z or hydrocracking process. Some parts are also decomposed to generate chlorine compounds such as hydrogen chloride. 'Or, such waste plastics often contain alkali salt such as soy sauce, miso, and salt. Therefore, in the method of the present invention, it is preferable to provide either a centrifugation step or a water washing step as the dechlorination step.

[Centrifuge separation process]

By installing a solid-liquid separator between the hydrocracking step and the fractionating step, here, a centrifugal separation step, the solid content such as chlorine and catalyst in the plastic solution is separated as a residue. Can be removed. Through this step, a high-quality pitch (hydrogenated pitch) free from solids can be obtained by further reducing-pressure distillation of the bottom oil of the fractional distillation.

[Water washing process]

In this step, water is added to and mixed with the plastic solution obtained in the dissolution step or hydrocracking step, and the water-soluble chlorine content in the solution or the water-soluble chlorine suspended in the solution is mixed. After extracting the water into water, it is removed by liquid separation. Specifically, a water washing process by liquid-liquid extraction can be exemplified.

The mixing treatment with water in this step may be either batch type or continuous type. processing The temperature is preferably 1550 to 2550 ° C. If it is 1500 ° C or higher, the mixed state becomes better and the transfer of chlorine to water becomes easier. In addition, since the cleaning efficiency is saturated even at high temperatures, it is economically appropriate to be 2500 ° C or less.

The amount of water added to the solution is preferably from 0.1 to: L 0 times, particularly 1 to 4 times by weight. If it is 0.1 times or more, the operation of phase separation of the solution and water is easy. In addition, even if the amount of water is increased, the extraction amount of water-soluble chlorine is saturated, so it may be about 10 times economically.

In the method of the present invention, most of the chlorine content is removed by the above-described centrifugal separation step or water washing step. Therefore, in the next fractionation step, the boiling point of 33 ° C. or higher is extremely low. A heavy fraction is obtained. In the conventional method without a centrifugal separation process or a water washing process, it is necessary to increase the distillation temperature when attempting to remove chlorine compounds contained in heavy fractions having a boiling point of 330 ° C or higher by distillation. . When the distillation temperature is raised, polycondensation due to heat occurs, and the aromatic compound becomes heavier, that is, has a higher boiling point, so that it cannot be distilled off and is difficult to separate and recover by distillation. Hereinafter, an apparatus suitable for the above-described plastic processing will be described. The plastic processing apparatus and the benzene production apparatus may have the same configuration. That is, the present application includes a dissolution tank equipped with a stirrer and a heating device up to 250 ° C., a pressure reaction vessel capable of withstanding 120 kg / cm ² G at 500 ° C., a fractionator, and a chloride. An invention of a plastic processing apparatus provided with a thermal decomposition tank resistant to hydrogen and chlorine gas is also provided.

FIG. 1 is a schematic explanatory view showing an embodiment of the plastic processing apparatus of the present invention. However, the present invention is not limited to FIG. The following description is based on the drawings. Benzene ring-containing plastics (hereinafter also applicable to mixed plastics or waste plastics containing benzene ring-containing plastics) 11, coal tar (solvent) 12, and catalyst 13 are agitator (not shown) and 2 5 Heating device up to 0 ° C

It is mixed and dissolved in a dissolution tank 1 equipped with (not shown). The heating temperature of the dissolution tank is preferably 1550 to 400 ° C. The solution of the benzene ring-containing plastic obtained here is a pressure reactor (also called a hydrocracking reactor) that can withstand 120 kg / cm¾ at 500 ° C with a pump (not shown) 3 The liquid is sent to

In addition, hydrogen or a gas containing hydrogen as a main component is supplied to the pressure reaction vessel 3. At this time, in FIG. 1, the majority of the gas discharged from the pressure reaction vessel 3 is circulated in order to improve economic efficiency, and a part of the gas is discarded as the exhaust gas 21 so as to maintain the hydrogen concentration at a predetermined concentration. I'm trying to make 15 up. However, do not circulate the exhausted gas, use it as a heating source for this plant, discard the entire amount of gas discharged from the pressure reaction vessel 3 while supplying a new amount of hydrogen, or use it for other purposes. You can also. In the pressure reaction vessel 3, if the waste plastic contains polystyrene, the molecular chain (main chain) is broken and hydrocracking reaction occurs mainly due to the effect of the catalyst 13 to produce ethylbenzene. Furthermore, BTXs (benzene, toluene, xylene, etc.), methane, ethane, etc. are generated by the decomposition of the alkyl chain of ethylbenzene and the disproportionation reaction of the product. The conventional thermal decomposition of plastics alone often produces styrene with an unsaturated alkene on the benzene ring. However, in the hydrocracking reaction of the present invention, the reaction proceeds mildly, and hydrogen atoms are supplied to the main chain cleavage part of the polystyrene, whereby an alkyl chain (saturated hydrocarbon) is added to the benzene ring. More ethylbenzene is used. In addition, the alkyl group of ethylbenzene is a single bond and is more easily cleaved than the double bond of styrene, which increases the yield of benzene and toluene. The

In addition, when polyethylene or polypropylene is present, the main chain is mainly broken, so that mainly C 3 to C 4 gas fractions are produced.

In addition, other thermosetting resins such as phenol resin, polyethylene terephthalate, etc. become benzenes by hydrocracking, and some become heavy oils (including pitches). On the other hand, coal tar used as a solvent is partly decomposed and lightened by reaction with hydrogen in the gas, but a part of it may produce pitch fraction due to polycondensation reaction. At this time, chlorine reacts with a monocyclic aromatic compound formed by hydrogenolysis of a plastic, and an aromatic compound such as a monocyclic, bicyclic or tricyclic ring in a solvent, and 0.1 to 0.00. About 2% by mass of aromatic chlorine compounds are by-produced, and the concentration of organochlorine compounds in cracked oil increases.

The liquid product discharged from the pressure reaction vessel 3 is sent to a distillation column (fractional distillation column) 6 where C 3 to C 4 gas fraction 22, BTX fraction 23, light fraction 24, heavy fraction Fractionated to 25. In FIG. 1, the number of distillation columns 6 is one, but fractional distillation may be subdivided by providing an atmospheric distillation column and a vacuum distillation column. As the distillation column, ordinary ones such as an atmospheric distillation column and a vacuum distillation column (vacuum distillation column) can be used. In addition, in order to recover the purified benzenes from the benzene fraction, a purification device such as a dedicated distiller may be provided. If the light fractions 24 contain organochlorine compounds, their boiling points are not so high that they can be easily removed by precision distillation. That is, since the organochlorine compound has a low boiling point, it can be fractionated without polycondensation in distillation.

On the other hand, as described above, the heavy fraction 25 is concentrated in chlorine, and as such, no use can be found.

However, the heavy fraction fractionated in the distillation tower is hydrogenated in the hydrocracking reaction and contains hydrogen. The amount is increasing, that is, the molecular structure with many hydrogen atoms in the molecule, that is,

H / C (ratio of hydrogen atom to carbon atom) is getting bigger. Therefore, if the heavy fraction is pyrolyzed, it is possible to increase the production of light fractions such as benzenes. At the same time, it is possible to obtain coatas. In comparison, the amount is very short.

Therefore, the apparatus of the present invention has a thermal decomposition tank 7 having resistance to hydrogen chloride and chlorine gas for effectively using the heavy fraction. Among these, it is preferable that the pyrolysis tank 7 is a plastic processing apparatus that is at least one selected from the group consisting of a coker, a coke oven, and a coal reforming furnace. The temperature in the pyrolysis tank 7 is preferably 400 to 600 ° C. For example, the 'heavy fraction 25 is sent to a pyrolysis tank 7 such as a coker, and discharged as a cracked BTX fraction 28 and a coatas 26.

In Fig. 1, an optional washing tower 9 is also installed. Decomposition BTX fraction 28 contains hydrogen chloride derived from chlorine originally present in heavy fraction 25 (generated by decomposition in pyrolysis tank 7) 27. To remove it. As the cleaning liquid used in the cleaning tower 9, water, sodium hydroxide, potassium hydroxide, or the like can be used. Since the chlorine concentration of the Cotas 26 obtained in this way is significantly reduced, it can be properly disposed as a raw material in existing processes such as sintering machines, coke ovens, or blast furnaces.

FIG. 2 is a schematic view showing an embodiment of another plastic processing apparatus according to the present invention. A difference from the embodiment shown in FIG. 1 is an example in which a coke oven is used as the pyrolysis tank 7 although the washing tower 9 is not provided. In this equipment, the heavy fraction 25 is supplied to the pyrolysis tank (coatus furnace) 7 together with the coal 16 and pyrolyzed in the coal-coating process. The obtained Kotas 26 is supplied to blast furnaces and used as a raw material for iron making. FIG. 3 is a schematic view showing an embodiment of another plastic processing apparatus according to the present invention. A difference from the embodiment shown in FIG. 2 is an example in which a coal mixer 8 is used instead of the pyrolysis tank 7. It is a device that obtains coal 31 that constitutes blended coal by mixing heavy fraction 25 obtained in the fractionation step together with non-slightly caking coal 16 with coal mixer 8. The obtained coal is separately added to the blended coal and pyrolyzed in a coke oven (not shown).

In the present invention, heavy fraction 25 and coal 16 can be mixed in coal mixer 8 and molded as necessary to reform coal (non-slightly caking coal) 16.

The present application also provides an invention of a plastic processing apparatus further provided with either a centrifuge or a separator equipped with a heating device and a water injection device up to 250 ° C. before the fractionator. To do. .

FIG. 4 is a schematic view showing an embodiment of another plastic processing apparatus according to the present invention. The difference from the embodiment shown in FIG. 2 is that a liquid one-liquid extractor 2 is provided as a water washing device between the pressure reaction vessel 3 and the distillation column 6 and the hydrogenolysis reaction generated in the pressure reaction vessel 3 is performed. The removal of water-soluble chlorine content 27 in the product is performed. By adding and mixing water to the hydrocracking reaction product, Na a C 1, KC 1, Fe C 1 _2, etc. in the hydrocracking reaction product are greatly transferred to the water phase. Separation and removal of water with transferred chlorine content reduces the amount of chlorine contained in hydrocracked oil. Therefore, in the heat treatment process, the ratio of forming stable chlorides is higher than in the case of FIG. 2, which is preferable.

FIG. 5 is a schematic view showing an embodiment of another plastic processing apparatus according to the present invention. The difference from the embodiment shown in FIG. 2 is that a centrifugal separator 5 is provided between the pressure reaction vessel 3 and the distillation column 6, and the hydrogen content in the hydrocracking reaction product produced in the pressure reaction vessel 3 is different. 2 7 is to be removed. The product of hydrocracking reaction is normal temperature due to low viscosity However, it is preferable to supply at 200 ° C. for centrifugal separation at a high temperature because the separation efficiency is further improved. Chlorine content 27 is separated as the residue from the centrifugal separator 5, and a hydrocracking reaction product with reduced chlorine content is obtained as the supernatant. The supernatant hydrocracking reaction product is sent to the distillation column 6 where C 3 to C 4 gas fraction 2 2, BTX containing BTX fraction 2 3, light fraction 2 4, heavy It is fractionated into mass fractions 25. The heavy fraction 25 with less chlorine content is placed in the pyrolysis tank 7. Example

[Invention Example 1]

The processing apparatus shown in FIG. 5 was used. Waste plastic recovered from the fish market is supplied to dissolution tank 1 held at 200 ° C at 9.6 kg / hr, and anthracene oil in the coal tar fraction is 22.4 kgZr as a solvent. Supplied. Was added converter dust (F e ₂ 〇 ₃₎ at a rate of 1.5kgZhr as a catalyst. The hydrogenation reaction was performed at a temperature of 450 ° C, a reaction pressure of lO.lMPa (100 atm), and a residence time of 1 hr. At this time, hydrogen gas 15 was supplied at 2.5 Nm ³ Zlir. After removing the residue from the reaction product with a centrifugal separator 5, the supernatant is sent to a distillation column (fractional distillation column) 6 and a fraction mainly composed of BTX having a boiling point up to 1 80¾ (BTX fraction) 2 3. Divided into light fraction 24 with a boiling point of 180-330 ° C and heavy fraction 25 with a boiling point of 330 ° C or higher. The heavy fraction 25 was supplied to a coker (pyrolysis tank 7) and pyrolyzed at 500 ° C to obtain a decomposed BTX fraction (not shown) and coatas 26. Chlorine content in the resulting Kotasu is 0.03 mass ^_0/0, were subjected to the original family of sintering machines. ,

On the other hand, the decomposed BTX fraction was gas-washed in a washing tower (not shown) using a sodium hydroxide aqueous solution as a washing liquid. Removes hydrogen chloride contained in the washing tower. The BTX fraction (not shown) was combined with the BTX fraction 23 distilled from the distillation column 6 and purified with a small distillation column to collect benzenes. Table 1 shows the amount of benzene recovered. On the other hand, as Comparative Example 1, the same hydrocracking and distillation operations as in Invention Example 1 were performed except that the heavy fraction was not pyrolyzed. The amount of benzene recovered in this case is also shown in Table 1.

[Invention Example 2]

Using a flow of processing apparatus shown in FIG. 2, to simulate the waste plastic City巿waste as plastic, polystyrene 3 0 mass ^_0/0, polyethylene 35 weight ^_0/0, polypropylene 3 0 mass ^_0/0 And a mixture 11 of 5% by weight of butyl chloride was prepared. This mixture was supplied at 9.6 kg / Υι r to dissolution tank 1 maintained at 200 ° C., and anthracene oil from the coal tar fraction was supplied at 22.4 kg ghr as solvent 12. Converter dust as a catalyst 1 3 (F e ₂ 〇 ₃ main component) was added 1 at a rate of 5 kg Z hr.

The hydrocracking was carried out at a temperature of 4500 ° C in the pressure reaction vessel 3, a reaction pressure of 10 IMP a (100 atm), and a residence time of 1 hr. At this time, hydrogen gas 15 was supplied at 2.5 Nm Vhr. The reaction product (cracked oil) is sent to the distillation column 6 and a C 3 to C 4 gas fraction 2 2, a fraction containing benzenes with a boiling point up to 200 ° C. (benzene fraction) 2 3 It was divided into a light fraction 24 having a boiling point of 200-330 ° C and a heavy fraction 25 having a boiling point of 330 ° C or higher.

Since heavy fraction 25 was discharged at 1 6. O kg / hr, 10.00 O kg / It was added at hr and introduced into the heat treatment tank 7. The residence time was 1 hour at 400 ° C, reforming the inferior coal, and fixing the chlorine in the heavy fraction in a stable state.

The heat-treated product (modified coal) obtained was subjected to X-ray photoelectron spectroscopy and X-ray diffractometer. analyzed. The N a C 1 to modified _{coal, KC 1, F eC l 2} , Ca C l 2, chlorine as such Mg C 1 ₂ was confirmed to exist in a stable state.

Also, the following test was conducted on the reformed coal. First, there are two types of blending: caking coal base blended coal with 10% by weight modified coal as Invention Example 2 and 10% by weight non-modified coal with Comparative Example 2. Charcoal was made. The base blended coal is as shown in Table 2. Coalization degree (Ro), Gisela maximum fluidity (MF), and total inert

It was prepared by mixing (TI), ash, and coal (coking coal for coke) of four brands (A Coal, B Coal, C Coal, and D Coal). A can firing test was conducted for each blended coal. That is, after 7 hours of dry distillation in a coke oven with a furnace temperature of 1100 ° C :; The packing density of the coal blend was 0. 8TZ m ^3. After preparing the coatus in this way, the drum strength (DI ³ ° ₁₅ ) of the coatus was measured according to JIS. Table 3 shows the measurement results. The can firing test is a firing test using a rectangular steel can (20 liters in volume) that has two sides that are almost the same length as the 45-cm furnace width of the actual Kotas furnace. .

As shown in Table 3, the drum strength of Invention Example 2 is improved as compared with that of Comparative Example 2, indicating that the inferior coal has been modified.

[Invention Example 3]

Using a flow of processing apparatus shown in FIG. 3, to simulate the waste plastic in municipal waste as plastic, polystyrene 30 mass ^_0/0, polyethylene 35 weight ^_0/0, polypropylene 30 wt%, and chloride Bulle 5 mass ^_0/0 mixture 11 was prepared. This mixture was fed at 9.6 kgZlir to a dissolution tank maintained at 200 ° C., and an anthracene oil of a coal tar fraction as solvent 12 was fed at 22.4 kgZhr. Converter dust as a catalyst 13 (F e ₂ 〇. Main component) was added 1 at a rate of 5 kg / hr. The hydrocracking was performed at a temperature of 450 ° C, a reaction pressure of 10. IMP a (100 atm), and a residence time of 1 hr. At this time, hydrogen gas 15 was supplied at 2.5 Nm ′ ³ / hr. The reaction product (cracked oil) is sent to the distillation tower 6 and the gas fraction 22 of C3 to C4, the fraction containing benzene having a boiling point up to 200 ° C (benzene fraction) 23, the boiling point 200 to 200 Divided into light fraction 24 at 330 ° C and heavy fraction 25 with boiling point above 330 ° C.

Since heavy fraction 25 was distilled at 16. O kg / r, mixed heavy fraction 25 and coal (wheatbank coal from South Africa, ground to 60 JIS mesh) 16 Introduced into a coal mixer 8 that also serves as a molding machine. The heavy fraction was 80 ° C to improve transportability, but the molding temperature was room temperature (20-30 ° C), and an amount of 10% by mass was added to the coal.

Two types of blended coal were produced: a mixture of caking coal base blended with 10% by weight modified coal as Invention Example 3, and a blend of 10% by weight Witbank coal as Comparative Example 3. . The base blended coal has four grades (Coal A, B Coal, Coal Degree (Ro), Gisser Maximum Fluidity (MF), Total Inert (TI), and Ash (as well as blending ratio) shown in Table 2. Coal (coking coal for Cotas) was prepared by mixing C coal and D coal. A can firing test was conducted on 15 kg of each blended coal. In other words, after 7 hours of dry distillation in a coke oven with a furnace temperature of 1100 ° C, the water was discharged from the furnace and sprinkled with fire. The packing density of the blended coal was 0.8 T / m ³ . After preparing the coatus in this way, the drum strength (DI ³ ° ₁₅ ) of coatus was measured according to JIS. Table 4 shows the measurement results.

In Invention Example 3, the concentration of hydrogen chloride contained in the gas generated during dry distillation was measured. For the measurement, all the generated gas is collected in one container and the dry distillation is completed. And then analyzed. The measurement results of hydrogen chloride concentration are also shown in Table 4.

Furthermore, as Comparative Example 4, the same blended coal and heavy fraction as in Comparative Example 3 (0.15 kg, the same as the amount present in the blended coal of Inventive Example 3) were placed separately and subjected to the can firing test. The amount of hydrogen chloride generated by thermal decomposition at 1100 ° C, the same as the furnace temperature, was investigated. The heating rate was the same at 3 ° C Zmin. Table 4 shows the analysis results.

As shown in Table 4, the drum strength of Invention Example 3 is higher than that of Comparative Example 3, indicating that the coal is being reformed. Further, from Table 4, in the invention example 3, the majority of the chlorine contained in the heavy fraction reacts with inorganic matter in the coal, N a C 1, KC 1 , C a C 1 2, Mg C 1 2 , etc. It can be seen that the amount of hydrogen chloride that corrodes the equipment is reduced by forming stable chlorides.

table 1

Invention Example 1 Comparative Example 1

Benzene recovery 11.5 Kg / hr 9.8 Kg / hr d d

Table 2 0 0

Viscosity $ riJ Ro MF TI

(%) (ddpm) (%) (%) Mixing ratio (mass%)

A gray 21222 17.9 8. 8 15

B Charcoal 1.2 F 39 9. 7 32

C charcoal 1.22 54 36.2 7. 5 23

D charcoal 513 3 C1.0 6.3 30 Base coal 1.10 234 31.4 8.0

(Weighted average) Table 3

Invention Example 2 Comparative Example 2

DI ³⁰ ₁₅ 91. 1 80.3

Table 4

(ppm

Industrial applicability

According to the present invention, a benzene ring-containing plastic, particularly a waste plastic containing at least a benzene ring-containing plastic, is used as a raw material, and at the same time, benzenes that are extremely useful in the chemical industry and the pharmaceutical industry are obtained. This makes it possible to effectively use other cracked oils. Therefore, it can contribute widely to industry as chemical recycling of waste plastic.

Claims

The scope of the claims

1. a step of dissolving a plastic having a benzene ring in a solvent hardly soluble in water; a step of hydrocracking the obtained plastic solution having the benzene ring; fractionating a product of the hydrocracking step A process; and

Pyrolyzing at least a portion of the heavy fraction of the fractionation step;

A method for processing plastic.

2. The plastic treatment method according to claim 1, further comprising a dechlorination step before the fractionation step.

3. The method for treating plastic according to claim 2, wherein the dechlorination is performed by centrifugation.

4. The method for treating plastic according to claim 2, wherein the dechlorination is washing with water.

5. The method for treating plastic according to claim 1, wherein the thermal decomposition is coking of at least a part of the heavy fraction.

6. The method for treating plastic according to claim 1, wherein the thermal decomposition is performed together with coal coalification by charging at least a part of the heavy fraction into a coke oven.

7. The plastic processing method according to claim 6, wherein at least a part of the heavy fraction is mixed with the coal before charging the coke oven.

8. The method for treating plastic according to claim 7, wherein the temperature at which at least a part of the heavy fraction is mixed with the coal is 20 to 100 ° C.

9. The method for treating a plastic according to claim 7 or 8, wherein a mixture of at least a part of the heavy fraction and the coal is formed.

10. The method for treating plastic according to claim 2, wherein the thermal decomposition is performed in a step of modifying at least a part of the heavy fraction with coal and heating to reform the coal.

11. The method for treating plastic according to claim 1, wherein the thermal decomposition is performed at 400 to 600 ° C.

12. The method for treating plastic according to claim 1, wherein the boiling point of the heavy fraction is 330 ° C or higher.

13. The plastic treatment method according to claim 1, wherein the plastic having a benzene ring is a mixture of a plastic having a benzene ring and another plastic.

14. The plastic treatment method according to claim 1, wherein the plastic having a benzene ring is waste plastic containing at least a plastic having a benzene ring.

15. The plastic processing method according to claim 1, wherein the plastic having a benzene ring is a plastic containing at least polystyrene.

16. The method for treating plastic according to claim 1, wherein the solvent is at least one selected from the group consisting of coal tar and coal tar distillation fraction.

17. The method for treating a plastic according to claim 1, wherein the product of the hydrocracking reaction step is benzene.

18. Dissolution tank with stirrer and heating device up to 250 ° C;

Pressure reactor capable of withstanding 120Kg / cm ² G at 500 ° C;

A fractionator; and

Thermal cracking tank resistant to hydrogen chloride and chlorine gas;

Plastic processing equipment with.

19. The plastic processing apparatus according to claim 18, further comprising a centrifuge before the fractionator.

20. Before the fractionator, place a separator equipped with a heating device up to 250 ° C and a water injection device. The plastic processing apparatus according to claim 18, further provided.

21. The plastic processing apparatus according to claim 18, wherein the pyrolysis tank is at least one selected from the group consisting of a coke oven, a coker and a coal reforming furnace.

2 2. A melting step in which the plastic and solvent are mixed and heated to dissolve the plastic,

Hydrocracking reaction of the plastic solution obtained in the dissolving step in the presence of a catalyst to perform hydrocracking reaction; and

A distillation process in which a hydrocracking reaction product produced in the hydrocracking process is distilled to obtain a heavy fraction;

And a pyrolysis step of pyrolyzing the heavy fraction obtained in the distillation step.