JP2007291289A - Method for treating plastic material, device for the same, method for producing benzenes and device for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for treating plastic materials capable of obtaining benzenes and reducing chlorine concentration, i.,e., the amount of organic chlorine compounds in decomposition oil produced as a byproduct, a device for the same, a method for producing benzenes and a device for the same. <P>SOLUTION: This method (device) for treating the plastic materials comprises a dissolving process (dissolving vessel 1) of the plastic materials by mixing the plastic material with solvent, a process of extracting and removing water soluble chlorine content (extracting equipment 2) by adding water to the solution obtained in the dissolving process (dissolving vessel 1), and extracting the water soluble chlorine in the solution with water and then removing water, and a process of performing hydrogenolysis reaction (hydrogenolysis reaction equipment 3) by reacting the solution obtained by removing the water soluble chlorine content by the water soluble chlorine content-extracting and removing process (extracting equipment 2), with hydrogen in the presence of a catalyst. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a plastic processing method and a processing apparatus for effectively using plastic waste, and a manufacturing method and a manufacturing apparatus for benzenes.

  As a technique for hydrocracking general waste plastics to obtain benzene or a benzene derivative, that is, benzenes, there is a technique disclosed in Patent Document 1.

In Patent Document 1, hydrogen is added to a liquid monocyclic or polycyclic aromatic compound containing waste plastic that has been liquefied by heating to cause a hydrogenolysis reaction (hydrogenolysis reaction), and the reaction product obtained The product is reacted in the presence of a cyclization catalyst to obtain benzenes.
JP 2003-321682 A

  According to the technique disclosed in Patent Document 1, benzenes can be obtained as a hydrocracking reaction product. However, since chlorine is present in the waste plastic, an aromatic chlorine compound is simultaneously produced as a by-product and removed. It is difficult. There is also a problem that the chlorine concentration of cracked oil, which is one of the products of hydrocracking reaction, becomes high. In particular, there is a problem that a large amount of chlorine is contained in a light fraction or a heavy fraction having a boiling point of 200 ° C. or higher, which is a hydrocracking reaction product. Thus, since various fractions contain a large amount of chlorine, they cannot be used as fuel oil or carbon black oil as they are.

  The present invention has been made in view of the above points, and in addition to obtaining benzenes, a chlorine treatment method in a by-product cracked oil, that is, a plastic treatment method capable of reducing the amount of an organic chlorine compound, and a treatment apparatus thereof, and A process for producing benzenes and a production apparatus therefor are provided.

  In order to solve the above-mentioned problems, the present inventors have made extensive studies. As a result, after dissolving the plastic in the solvent, further adding and mixing water, we found that most of the chlorine was transferred to water, and suppressed the by-production of organochlorine compounds in the subsequent hydrocracking reaction. Thus, it was found that benzenes can be obtained. That is, it is a method of chemical recycling of waste plastics that can greatly reduce the by-product of organochlorine compounds.

The present invention has been made based on the above findings and has the following characteristics.
[1] A melting step of mixing and heating a plastic and a solvent to dissolve the plastic;
Adding water to the solution obtained in the dissolving step, extracting the water-soluble chlorine content in the solution into water, and then removing and removing the water-soluble chlorine content,
A hydrocracking step of performing a hydrocracking reaction by reacting the solution from which water-soluble chlorine content has been removed by the water-soluble chlorine content extracting / removing step with hydrogen in the presence of a catalyst. Plastic processing method.
[2] The plastic processing method according to [1], wherein the plastic contains polystyrene.
[3] The method for treating plastic according to [1] or [2], wherein the solvent is coal tar and / or coal tar distillation fraction.
[4] The plastic processing method according to any one of the above [1] to [3], wherein a reaction product in the hydrocracking step is a benzene.
[5] A dissolving step of mixing and heating polystyrene and a solvent to dissolve the polystyrene;
Adding water to the solution obtained in the dissolving step, extracting the water-soluble chlorine content in the solution into water, and then removing and removing the water-soluble chlorine content,
A hydrocracking step of reacting a solution from which water-soluble chlorine content has been removed by the water-soluble chlorine content extraction / removal step with hydrogen in the presence of a catalyst to obtain a benzene by performing a hydrocracking reaction. A method for producing benzenes, comprising:
[6] The method for producing benzenes according to [5], wherein the polystyrene is waste polystyrene.
[7] A dissolution tank for mixing and heating a plastic and a solvent to dissolve the plastic;
An extractor for removing water after adding water to the solution obtained in the dissolution tank and extracting water-soluble chlorine in the solution into water;
A hydrocracking reactor in which a solution from which water-soluble chlorine has been removed by the extractor and hydrogen are reacted in the presence of a catalyst to perform a hydrocracking reaction;
A plastic processing apparatus comprising: a separation device for separating and recovering a reaction product obtained in the hydrocracking reactor from a solution.
[8] A dissolving tank in which polystyrene and a solvent are mixed and heated to dissolve the polystyrene;
An extractor for removing water after adding water to the solution obtained in the dissolution tank and extracting water-soluble chlorine in the solution into water;
A hydrocracking reactor in which a solution from which water-soluble chlorine has been removed by the extractor and hydrogen are reacted in the presence of a catalyst to perform a hydrocracking reaction;
An apparatus for producing benzene, comprising a separation device for separating and recovering benzenes obtained in the hydrocracking reactor from a solution.

  According to the present invention, even when plastics, particularly waste plastics, are used as raw materials, plastics that can produce benzenes without the by-product of light and heavy fractions containing a large amount of chlorine. And a treatment apparatus thereof, a method of producing benzenes, and a production apparatus thereof are provided.

  The configuration of the present invention is as described above. Hereinafter, each component of the present invention will be described more specifically.

[Dissolution process]
Here, the plastic and the solvent are mixed and heated to dissolve the plastic in the solvent. As the plastic, municipal waste waste plastics containing chlorine such as vinyl chloride resin can be used, and industrial waste, polyethylene, polypropylene, polystyrene alone or a mixture of many of these (waste plastic) May be used. There is no particular need to adjust the particle size of plastic (same for waste plastic; the same applies hereinafter), but it is desirable to crush from the viewpoint of shortening the melting time of the plastic. Moreover, if it is a small amount, it may contain a thermosetting resin or paper.

  The type of the solvent is not limited as long as it can dissolve (fluidize) the plastic and separate from the benzenes to be generated, that is, does not form a plurality of phases. However, a monocyclic, bicyclic or tricyclic aromatic compound (including various derivatives) or a mixture thereof is preferable in terms of compatibility. Above all, each distillation fraction of coal tar can be fluidized with thermosetting resins and papers, so it can be pumped to a treatment tank when mixed with water in the next process, which is extremely suitable. It is. As each distillation fraction of coal tar, not only coal tar (all fractions) but also creosote oil fraction and anthracene oil fraction produced in a coal tar distillation plant can be used. It may contain tar pitch.

  The mixing ratio of the plastic and the solvent is preferably 5 parts by mass / 95 parts by mass to 40 parts by mass / 60 parts by mass, respectively. In the case of 5 parts by mass / 95 parts by mass or less, the plant becomes large with respect to the amount of plastic processed, and the economic efficiency deteriorates. Moreover, when it exceeds 40 mass parts / 60 mass parts, fluidity | liquidity will deteriorate.

  With regard to the conditions for melting the plastic, it may be 150 ° C. or higher. When the temperature exceeds 400 ° C., the compound contained in the plastic or coal tar is polycondensed and the reaction resulting in a pitch fraction becomes remarkable, which is inconvenient in operation. Therefore, 400 ° C. or lower is preferable. Further, if the temperature exceeds 250 ° C., the volatilization of the light fraction becomes remarkable. In this case, it is desirable to perform the dissolution treatment in a sealed container. On the other hand, when the temperature is lower than 150 ° C., the dissolution rate of the plastic is slow and the dissolution tank becomes large.

[Water-soluble chlorine extraction / removal process]
Here, water is added to and mixed with the solution obtained in the dissolution step, and the water-soluble chlorine content in the solution is extracted into water and then removed to remove the water-soluble chlorine content in the solution. Remove. The mixing treatment with water may be either a batch type or a continuous type. The processing temperature is preferably 150 to 250 ° C. When the temperature is lower than 150 ° C., the mixed state is not good, and the rate of transfer of chlorine to water decreases. In addition, a significant increase in the migration rate of the chlorine content cannot be expected even when the temperature exceeds 250 ° C., and since the vapor pressure becomes high, an extremely thick container is required.

  The amount of water added to the solution is preferably 0.1 to 10 times, particularly 1 to 4 times in terms of mass ratio. If the amount of water is small, the phase separation of the solution and water will not work. Further, even if the amount of water is increased, the extraction amount of water-soluble chlorine is not increased, and the extraction container becomes large, which is not economical.

[Hydrolysis process]
Here, the hydrocracking reaction is performed by reacting the solution from which the water-soluble chlorine content has been removed by the water-soluble chlorine content extraction and removal step with hydrogen in the presence of a catalyst. As the catalyst used for the hydrocracking reaction, in the above mixing process, when the chlorine content is largely transferred to water and the feed of the hydrocracking reactor contains almost no chlorine, Co—Mo, Ni— Examples thereof include Mo, Ni—W-based catalysts, and iron catalysts (iron oxide, iron sulfide, iron sulfate, and fired products thereof). These catalysts can be supported on a carrier such as alumina (Al ₂ O ₃ ) or silica (SiO ₂ ) as necessary. However, when a large amount of chlorine is contained in the feed of the hydrocracking reactor, the noble metal component of the catalyst is deteriorated by forming a chloride, so that the catalyst performance is maintained even if it becomes a chloride. It is preferable to use an iron catalyst. In particular, converter dust generated by converter blowing in steelmaking, that is, iron particles of iron oxide, is preferable because solid-liquid separation in the subsequent stage is good. When the catalyst is used as a granular material, the particle size may be normal and may be about 0.01 to 10 mm. This catalyst may be used in any reaction mode such as a fluidized bed, a fixed bed, and a slurry bed.

  Regarding the addition amount of a catalyst, 1-10 mass% is preferable with respect to a solution, and 3-5 mass% is especially suitable. When the amount of the catalyst is small, the hydrocracking reaction is slow, and no significant effect is observed even when the amount exceeds 10% by mass.

  The catalyst may be added from the beginning, or may be added after extracting and removing chlorine.

  The hydrocracking reaction may be performed in either the liquid phase or the gas phase, the reaction temperature is about 300 to 500 ° C, preferably about 400 to 450 ° C, and the pressure is 1.0 to 20.3 MPa (10 to 200). Atmospheric pressure), preferably 5.1 to 10.1 MPa (50 to 100 atmospheres).

  Here, examples of the reaction product in this hydrocracking step include benzenes such as benzene, toluene, xylene, and ethylbenzene.

  Hereinafter, a plastic processing apparatus and a benzene manufacturing apparatus in which the above-described steps are performed will be described. In addition, the said plastic processing apparatus and the manufacturing apparatus of benzene can be set as the same structure.

  FIG. 1 is a schematic view showing an embodiment of a plastic processing apparatus and a benzene production apparatus according to the present invention. However, the apparatus configuration according to the present invention is not limited to the case shown in FIG. Hereinafter, it demonstrates according to this schematic.

  The plastic (same for waste plastic, the same applies hereinafter) 11, coal tar (solvent) 12, and catalyst 13 are mixed and dissolved in the dissolution tank 1. The operation temperature of the dissolution tank 1 is preferably 150 to 400 ° C. for the reason described above. The obtained lysate (solution) is sent to the extractor 2 by a pump.

  In the extractor 2, water is added and stirred. Then, the stirring is stopped, and the plastic / coal tar solution and water are separated using the specific gravity difference. Since water contains a large amount of chlorine, treat it appropriately. On the other hand, the melted plastic / coal tar is fed to the hydrocracking reactor 3. In order to continuously supply the plastic coal coal tar melt to the hydrocracking reactor 3, a plurality of batch type extractors 2 may be provided. In addition, for example, a plurality of partitions are attached to one extractor to provide a function of the mixing region and the stationary region, and overflow of plastic / coal tar lysate and water movement between the mixing region and the stationary region, etc. It does not matter if you do this.

  As described above, the hydrocracking reaction in the hydrocracking reactor 3 may be performed in either a liquid phase or a gas phase, and the reaction temperature is about 300 to 500 ° C, preferably about 400 to 450 ° C. The pressure is about 1.0 to 20.3 MPa (10 to 200 atm), preferably 5.1 to 10.1 MPa (50 to 100 atm). The hydrocracking reactor 3 is supplied with hydrogen or a gas 15 containing hydrogen as a main component. In this case, in the example shown in FIG. 1, in order to improve the economy, most of the gas discharged from the hydrocracking reactor 3 is circulated so that the hydrogen concentration is maintained at a predetermined concentration. A part of the discharged gas is discarded as the exhaust gas 21 and the hydrogen 15 is made up. However, the total amount of hydrogen is newly supplied without circulating the exhaust gas, and the total amount of gas exhausted from the hydrocracking reactor 3 is discarded, used as a heating source for this plant, or for other uses. It may be used.

  In the hydrocracking reactor 3, due to the effect of the added catalyst 13, ethylbenzene is generated mainly by the molecular chain (main chain) cleavage and hydrogenation, and the alkyl chain is decomposed. The disproportionation reaction produces BTXs, methane, ethane and the like. Usually, thermal decomposition alone often produces styrene with an unsaturated alkene on the benzene ring, but here the reaction proceeds mildly and hydrogen atoms are supplied to the main chain scissions. More ethylbenzene with an alkyl chain (saturated hydrocarbon) added to the benzene ring.

  When polyethylene or polypropylene is present, the main chain is mainly broken, so that a gas fraction mainly composed of C3 to C4 is generated. Moreover, a part of thermosetting resin represented by phenol resin other than that, a polyethylene terephthalate, etc. becomes a heavy fraction (a pitch fraction is also included). On the other hand, coal tar often undergoes some hydrogenation and lightening mainly due to reaction with hydrogen in the gas, but a very small portion may produce a pitch fraction due to the polycondensation reaction.

  The liquid product discharged from the hydrocracking reactor 3 is sent to a distillation column (separator) 6 where a gas fraction 22 mainly composed of C3 to C4, a benzene fraction 23, creosote oil and anthracene. It is fractionated into a hydrogenated tar fraction (light fraction) 24 and a heavy fraction 25 corresponding to a lighter oil.

  In FIG. 1, the number of distillation columns (separation devices) 6 is one. However, the fractional distillation may be subdivided by providing an atmospheric distillation column and a vacuum distillation column. The hydrogenated tar fraction (light fraction) 24 may be a product, but a part or all of the hydrogenated tar fraction (light fraction) may be recycled to the dissolution tank 1 and used as the solvent 12.

  FIG. 2 is a schematic view showing an embodiment of another plastic processing apparatus and benzene production apparatus according to the present invention. 1 is different from the embodiment shown in FIG. 1 in that a solid-liquid separator, here a centrifugal separator 5 is provided between the hydrocracking reactor 3 and the distillation column (separation device) 6, and the inorganic substance in the plastic, catalyst The solid content such as is separated and removed. In this case, if the bottom of the distillation column 6 is further squeezed with a vacuum distillation column, a high-quality pitch (hydrogenated pitch) containing no solid content can be obtained.

[Invention Example 1]
Using a reactor of the flow shown in FIG. 2, a mixture of 30% by mass of polystyrene, 35% by mass of polyethylene, 30% by mass of polypropylene, and 5% by mass of vinyl chloride was prepared by simulating municipal waste waste plastic as plastic. did. This mixture was supplied at 9.6 kg / hr to a dissolution tank maintained at 200 ° C., and an anthracene oil of a coal tar fraction was supplied at 22.4 kg / hr as a solvent. As a catalyst which is also a chlorine fixing agent, converter dust was added at a rate of 1.5 kg / hr. The residence time of the dissolution tank was 0.5 hr. The solution of the plastic and anthracene oil was fed to a closed type extractor, and the chlorine content was transferred to hot water at 250 ° C. Two extractors were installed and operated alternately. The dechlorinated plastic and anthracene oil melt was fed to the hydrocracking reactor.

The hydrocracking reactor was subjected to hydrocracking at a temperature of 450 ° C., a reaction pressure of 10.1 MPa (100 atm), and a residence time of 1 hr. At this time, hydrogen gas was supplied at 2.5 Nm ³ / hr. The obtained hydrocracked oil is removed from the residue with a centrifuge, and then sent to a distillation column (separator). A gas fraction mainly composed of C3 to C4, mainly composed of benzenes having a boiling point of up to 200 ° C. Fractions, hydrogenated tar fractions, and hydrogenated pitch fractions. Furthermore, the hydrogenated tar fraction was divided into a fraction having a boiling point of 200 to 300 ° C., a fraction having a boiling point of 300 to 400 ° C., and a fraction having a boiling point of 400 ° C. or more (distillation apparatus not shown).

  The presence of benzenes, that is, BTX (benzene, toluene, xylene), ethylbenzene, etc. was confirmed using a gas chromatograph apparatus for the fraction mainly composed of benzenes. Moreover, the chlorine content contained in each fraction was quantified. The analysis results are shown in Table 1.

[Comparative Example 1]
The same reaction and distillation as in Example 1 of the present invention were carried out except that the plastic and anthracene oil solution having the same composition as in Example 1 of the present invention was not passed through an extractor and dechlorination was not performed, and each fraction was obtained. It was. The same analysis as in the first invention example is performed, and the analysis results are also shown in Table 1.

  From Table 1, it can be seen that the chlorine content of the fraction at 200 ° C. or higher is greatly reduced by using the method of the present invention.

It is explanatory drawing which shows typically the structure of the manufacturing apparatus of benzene which concerns on this invention. It is explanatory drawing which shows typically the structure of the manufacturing apparatus of the other benzenes concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dissolution tank 2 Extractor 3 Hydrocracking reactor 5 Centrifugal separator 6 Distillation tower 11 Plastic 12 Coal tar (solvent)
13 Catalyst 15 Hydrogen or hydrogen-based gas 21 Exhaust gas 22 Gas fraction 23 Benzene fraction 24 Light fraction 25 Heavy fraction 27 Chlorine 28 Residue

Claims (8)

A melting step of mixing and heating a plastic and a solvent to dissolve the plastic;
Adding water to the solution obtained in the dissolving step, extracting the water-soluble chlorine content in the solution into water, and then removing and removing the water-soluble chlorine content,
A hydrocracking step of performing a hydrocracking reaction by reacting the solution from which water-soluble chlorine content has been removed by the water-soluble chlorine content extracting / removing step with hydrogen in the presence of a catalyst. Plastic processing method.   2. The plastic processing method according to claim 1, wherein the plastic contains polystyrene.   3. The plastic processing method according to claim 1, wherein the solvent is coal tar and / or coal tar distillation fraction.   The method for treating plastic according to any one of claims 1 to 3, wherein a reaction product in the hydrocracking step is benzene. A melting step of mixing and heating polystyrene and a solvent to dissolve the polystyrene;
Adding water to the solution obtained in the dissolving step, extracting the water-soluble chlorine content in the solution into water, and then removing and removing the water-soluble chlorine content,
A hydrocracking step of reacting a solution from which water-soluble chlorine content has been removed by the water-soluble chlorine content extraction / removal step with hydrogen in the presence of a catalyst to obtain a benzene by performing a hydrocracking reaction. A method for producing benzenes, comprising:   The method for producing benzenes according to claim 5, wherein the polystyrene is waste polystyrene. A melting tank for mixing and heating a plastic and a solvent to dissolve the plastic;
An extractor for removing water after adding water to the solution obtained in the dissolution tank and extracting water-soluble chlorine in the solution into water;
A hydrocracking reactor in which a solution from which water-soluble chlorine has been removed by the extractor and hydrogen are reacted in the presence of a catalyst to perform a hydrocracking reaction;
A plastic processing apparatus comprising: a separation device for separating and recovering a reaction product obtained in the hydrocracking reactor from a solution. Mixing polystyrene and solvent, heating and dissolving the polystyrene,
An extractor for removing water after adding water to the solution obtained in the dissolution tank and extracting water-soluble chlorine in the solution into water;
A hydrocracking reactor in which a solution from which water-soluble chlorine has been removed by the extractor and hydrogen are reacted in the presence of a catalyst to perform a hydrocracking reaction;
An apparatus for producing benzene, comprising a separation device for separating and recovering benzenes obtained in the hydrocracking reactor from a solution.

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