JP2006199853A - Method for producing light aromatic compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a light aromatic compound from tar or pitch by effectively using hydrogen of a plastic. <P>SOLUTION: The method for producing the light aromatic compound comprises obtaining the light aromatic compound by hydrogeneration reaction of a mixture of tar and pitch with plastic, by which the light aromatic compound may be fractionated by distilling the product which is obtained by the hydrogeneration reaction using a distillation column 3, or the hydrogen is produced by modifying a gas component which is obtained by the distillation using a reformer 4 and the hydrogen may be added to the hydrogeneration reaction step 2. Further, the plastic is preferably waste materials. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for obtaining a light aromatic compound from a heavy aromatic compound such as tar or pitch.

Light aromatic compounds can be used for various uses such as solvents and chemical raw materials (starting materials), and have high utility value. Light aromatic compounds are produced by various methods.
For example, Patent Document 1 discloses a technique for producing a light aromatic compound by using heavy oils (ie, heavy aromatic compounds) such as tar and pitch as raw materials. This technology adsorbs coke precursors and coke obtained by thermal decomposition of heavy oils together with coke adsorbents in the presence of hydrogen to the coke adsorbents in the range of 2 to 10% by mass with respect to the raw oil. And removing the coke precursor and coke obtained in the first step in the presence of activated carbon, an iron compound, and hydrogen. This is a hydrocracking technology (hydrogenation reaction technology) of heavy oils comprising the second step.
Japanese Patent No. 3502499

However, the technique disclosed in Patent Document 1 not only requires expensive hydrogen gas to be produced by a separate process, but also makes the process of hydrogenating a heavy aromatic compound complicated, producing a light aromatic compound. There was a problem that the cost increased.
This invention is made | formed in view of this point, and it aims at providing the method which can manufacture a light aromatic compound cheaply from tar and pitches, using hydrogen contained in a plastics effectively.

  In order to solve the above-mentioned problems, the inventors have made extensive studies. As a result, plastics, tars, and pitches that contain a large amount of hydrogen atoms in the molecule are reduced to lighter hydrogen in an atmosphere of hydrogen-rich gas obtained by the plastic reforming process that has mainly occurred only in molecular chain breakage (ie, It was found that a light aromatic compound can be obtained by hydrogenation reaction.

The gist of the present invention is as follows.
(1) A method for producing a light aromatic compound, wherein a light aromatic compound is obtained by hydrogenating a mixture / dissolved product of tar and / or pitch and plastic.
(2) A method for producing a light aromatic compound according to (1), wherein the product obtained by the hydrogenation reaction is distilled to fractionate the light aromatic compound.
(3) Production of a light aromatic compound characterized in that in (2) above, hydrogen is produced by reforming the gas component obtained by the distillation, and the hydrogen is added to the hydrogenation reaction step. Method.
(4) The method for producing a light aromatic compound according to any one of the above (1) to (3), wherein the plastic is waste.

  If the present invention is applied in producing a light aromatic compound, a process such as steam reforming or thermal decomposition of an organic compound to obtain hydrogen becomes unnecessary.

  According to the present invention, since a gas generation amount can be suppressed without separately providing an expensive hydrogen production apparatus, a light aromatic compound can be produced at low cost and in large quantities.

FIG. 1 is a schematic view showing an embodiment of a light aromatic compound production apparatus to which the present invention is applied (however, the present invention is not limited to FIG. 1). Hereinafter, a description will be given with reference to FIG.
As the plastic 11, a single product such as polyethylene, polypropylene, or polystyrene having a large amount of hydrogen atoms in the molecule, a mixture, or a material containing these plastics as a main component can be used. The plastic 11 may be unused or used (that is, waste). Use of waste plastic is preferable from the viewpoint of preventing environmental pollution as well as reducing the production cost of light aromatic compounds. As the waste plastic, it is preferable to use an industrial waste plastic in terms of avoiding corrosion of the apparatus, but a general waste based resin containing chlorine such as vinyl chloride resin may be used.

The tar 13 and pitch 12 are preferably coal-based, and a creosote oil fraction, anthracene oil fraction, pitch, and the like produced in a coal tar distillation plant are used. These may be used alone or as a mixture. Examples of the catalyst 14 used in the hydrogenation reaction (hereinafter referred to as a hydrogenation reaction catalyst) include iron and converter dust (Fe ₂ O ₃ ). In addition, iron oxide, Co-Mo, Ni-Mo, Ni-W-based catalyst, iron sulfate, and a fired product thereof can be used. These catalysts can be supported on a carrier such as alumina (Al ₂ O ₃ ) or silica (SiO ₂ ) if necessary. When used as a granular material, the particle size may be normal, and may be about 0.1 to 10 mm. This catalyst may be used in any reaction form such as a fluidized bed, a fixed bed, and a slurry bed.

  The raw materials (namely, plastic 11, tar 13, pitch 12, and hydrogenation reaction catalyst 14) are mixed and dissolved in dissolution tank 1. The operation temperature of the dissolution tank 1 is preferably 150 to 250 ° C. When the temperature is lower than 150 ° C, the dissolution rate is slow, and when the temperature exceeds 250 ° C, the amount of evaporation of tar (eg creosote oil, anthracene oil, etc.) increases. The raw material dissolved in this way is sent to the hydrogenation reactor 2 by a pump.

  The hydrogenation reaction may be either liquid phase or gas phase, the reaction temperature is about 300 to 500 ° C, preferably about 350 to 450 ° C, and the pressure is about 1.01 to 20.3 MPa (10 to 200 atmospheres), preferably 5.07 to 10.1. MPa (50-100 atm). The hydrogenation reactor 2 is circulated and supplied with the gas discharged from the reactor plus the hydrogen-rich gas discharged from the reformer 4. In the hydrogenation reactor 2, due to the effect of the added catalyst, a hydrogenation reaction (hydrocracking reaction) occurs with respect to tar and pitch by reaction with hydrogen in the gas. On the other hand, from the waste plastic, hydrogen necessary for hydrogenation of the C3 to C4 components and tar and pitch is generated by breaking the molecular chain.

  The product discharged from the hydrogenation reactor 2 is sent to the distillation column 3 and water corresponding to a gas fraction 25 mainly composed of C3 to C4, lightened creosote oil, anthracene oil and the like. It is fractionated into a hydrogenated tar fraction 21 and a hydrogenated pitch fraction 22 corresponding to a lighter pitch. In FIG. 1, only one distillation column is provided, but an atmospheric distillation column, a vacuum distillation column, or the like may be provided to subdivide the fractional distillation.

The light aromatic compound having a hydrogenated tar fraction of 21 and a hydrogenated pitch fraction of 22 is still a product. The gas fraction 25 mainly composed of C3 to C4 is sent to the reformer 4. In the reformer 4, a monocyclic aromatic compound 23 such as BTXs is generated and a hydrogen rich gas 27 is generated by the cyclization catalyst. BTXs are intermediate products, and the hydrogen rich gas 27 is mixed with the exhaust gas 26 (C3 to C4 components) of the hydrogenation reactor 2 and recycled to the hydrogenation reactor 2. In order to balance the materials, before adding the hydrogen rich gas from the reformer 4, a part of the exhaust gas 26 (C3 to C4 component) of the hydrogenation reactor 2 is withdrawn as off-gas 24, and a heating source such as the dissolution tank 1 It may be used as The cyclization catalyst is a zeolite type such as ZSM-5, ZSM-11, HZSM-5, or HZSM-11 carrying Ga, Zn, or Cu, that is, Ga-ZSM-5, Ga-HZSM-5, etc. Ni-Mo / Al ₂ O ₃ or the like can be used. This cyclization catalytic reaction (cyclization reaction) can also be carried out in a fluidized bed, a fixed bed or the like, and the particle size when used in the form of a granular material may be about 0.1 to 10 mm. The reaction temperature is 350 to 700 ° C, preferably around 500 ° C, and the reaction pressure is 0.1 to 1.01 MPa (1 to 10 atmospheres), preferably 0.10 to 0.20 MPa (1 to 2 atmospheres).

A light aromatic compound was produced from tars and pitches using the apparatus shown in FIG. At that time, a mixture of industrial waste polyethylene, polypropylene and polystyrene was used as the plastic 11. The mixture was fed at 9.6 kg / hr to a dissolving tank maintained at 200 ° C., and tar 13 was supplied with anthracene oil at 28.8 kg / hr and pitch 12 at 9.6 kg / hr. As the hydrogenation reaction catalyst 14, converter dust containing iron oxide as a main component was added at a rate of 288 g / hr. The hydrogenation reaction was carried out at a hydrogenation reactor temperature of 430 ° C., a reaction pressure of 10.1 MPa (100 atm), and a residence time of 1 hour. At this time, a gas having a hydrogen content of about 50% was supplied at 5 Nm ³ / hr. The reaction product was sent to the distillation column 3 and divided into a fraction 25 mainly composed of C3 to C4, a hydrogenated tar fraction (hydrogenated anthracene oil) 21, and a hydrogenated pitch fraction 22. A fraction 25 mainly composed of C3 to C4 was sent to the reformer 4 to obtain BTXs 23 and a hydrogen rich gas 27. A zeolite catalyst (Ga-HZSM-5) was used as the cyclization catalyst, the reaction temperature was 500 ° C., and the residence time was 0.5 min.

  Further, when hydrogenated anthracene oil was examined in detail by a mass spectrometer (GC-MS), in addition to the usual components of anthracene oil, BTXs, indenes, and tetralins that were not present in the original anthracene oil were also found. , Decaline and other light aromatic compounds were newly produced. Similarly, dihydropyrene could be identified and confirmed that pitch softening had occurred.

It is the schematic which shows one Embodiment of the manufacturing apparatus of the light aromatic compound to which this invention is applied.

Explanation of symbols

1 Dissolution tank 2 Hydrogenation reactor 3 Distillation tower 4 Reformer
11 Plastic
12 pitch
13 tar
14 Catalyst for hydrogenation reaction
21 Hydrogenated tar fraction
22 For hydrogenated pitch
23 Monocyclic aromatic compounds
24 off gas
25 Gas fraction
26 exhaust gas
27 Hydrogen rich gas

Claims (4)

  A method for producing a light aromatic compound, wherein a light aromatic compound is obtained by hydrogenating a mixture / dissolved product of tar and / or pitch and plastic.   2. The method for producing a light aromatic compound according to claim 1, wherein the product obtained by the hydrogenation reaction is distilled to fractionate the light aromatic compound.   The method for producing a light aromatic compound according to claim 2, wherein the gas component obtained by the distillation is reformed to produce hydrogen, and the hydrogen is added to the hydrogenation reaction step. The method for producing a light aromatic compound according to any one of claims 1 to 3, wherein the plastic is waste.