JPH0832889B2 - Treatment method for polystyrene waste - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for treating polystyrene waste, and in particular, a method for obtaining a high-octane gasoline base material and a high-value-added chemical raw material from polystyrene waste in high yield. Regarding

(Prior Art) It is well known that the treatment of waste has become a social problem with the increase in the production amount of plastics in recent years.
Depending on the type of plastic, the technological development of its reuse has reached the stage of practical use.

However, the recycling technology of polyolefin plastics, which is said to occupy about half of the production of thermoplastics in Japan, has not achieved sufficient practical effects except for small-scale reuse such as molding material. Not in.

Polystyrene, particularly expanded polystyrene, is used in large quantities as various food containers and the like because it is inexpensive and has excellent heat retention, but most of them are actually discarded.

(Problems to be Solved by the Invention) An object of the present invention is to provide an effective utilization method of polystyrene waste, and in particular, aromatic polystyrene which is useful as a raw material for high octane gasoline and high value-added chemicals from polystyrene waste. It is to provide a method for producing hydrogen oil in a high yield.

(Means for Solving the Problems) The present invention melts polystyrene waste, heats the melt to thermally decompose it in a liquid phase, and
A method for treating polystyrene waste is characterized in that catalytic conversion is carried out in a packed bed of zeolite having a constraint coefficient of 12 to produce and obtain aromatic hydrocarbon oil.

The polystyrene waste used in the method of the present invention is a film,
Although wastes in any form such as sheets and molded products may be used, wastes of expanded polystyrene products are particularly preferably used. These are usually pulverized by an appropriate means and then continuously supplied to the pyrolysis reaction tank as they are or while being heated and softened and melted by using an extruder or the like. It is desirable to soften and melt what is crushed afterwards.

In the method of the present invention, the essence is that the first-stage decomposition is carried out in the molten liquid phase of polystyrene. The heating temperature of the first-stage thermal decomposition reaction tank is preferably 200 to 450 ° C, and particularly preferably 250 to 400 ° C. The first-stage thermal decomposition reaction proceeds only by maintaining the molten polystyrene at a predetermined temperature condition, but it is also possible to use stirring in combination or to allow inorganic porous particles and the like to coexist in the reaction system. As the inorganic porous granular material, if it does not deform or deteriorate under the reaction conditions, its type, size, etc. are not particularly limited, but the size is usually 1 to 10 mm or so. preferable. Specific examples of such porous granular material include natural zeolite, bauxite, red mud and the like.

Thus, the vaporous products produced in the first-stage pyrolysis reaction tank are successively passed through the packed bed of zeolite and catalytically converted.

In the present invention, it is essential to use zeolite having a constraint coefficient in the range of 1 to 12 as a catalyst in the gas phase catalytic conversion in the second stage. The constraint index is defined, for example, in US Pat. No. 4,016,218.

Specific examples of such type of zeolite include ZSM-5, ZSM-
There are 11, ZSM-12, ZSM-23, ZSM-35, ZSM-38, ZSM-48 and the like, and ZSM-5 is particularly preferably used. ZSM-5 is a crystalline zeolite having the following lines in the synthesized state in its X-ray diffraction pattern.

Lattice plane spacing Relative strength 11.2 ± 0.2 S 10.1 ± 0.2 S 3.86 ± 0.08 VS 3.72 ± 0.08 S 3.66 ± 0.05 M Such zeolites are usually used in acid form (the original alkali metal is replaced with H), but it is necessary. Correspondingly, one having platinum or other metal is also used. Such zeolites usually have a particle size on their own or with a carrier such as alumina.
It is used after being molded into an arbitrary shape of about 0.1 to 10 mm.

This second-stage catalytic conversion reaction is 200-400 in normal operation.
C., preferably at a temperature of 250 to 350.degree. Such low temperature operation is unexpected from the conventional knowledge. The use of such a low temperature brings not only economical efficiency but also effects such as suppression of undesirable side reactions.

The use of the above-mentioned zeolite not only allows reduction of temperature conditions and stable continuous operation, but also has a remarkable effect on improvement of product quality and yield. Moreover, the effect is maintained even if this catalyst is regenerated and reused. The maintenance of the effect associated with this regeneration is particularly remarkable in the method of the present invention. Even a regenerated catalyst used in another reaction can be effectively used in the method of the present invention.

By the method of the present invention, aromatic hydrocarbon oil can be obtained in high yield. The components are mostly benzene, toluene and xylene isomers (o-, m- and p-xylene and ethylbenzene). These are called BTX and all have high utility value in the petrochemical industry. Therefore, it can be used as a raw material for chemicals after being separated into each component as necessary, and can be effectively used as a high-octane gasoline base material because of its component characteristics.

(Example) Next, this invention is demonstrated based on an Example. FIG. 1 is a sectional view of the apparatus used in the examples.

A used expanded polystyrene container having an expansion ratio of about 50 times was cut into small pieces, treated with steam at about 130 ° C. to remove air, and the resulting reduced pieces were crushed to about 5 mm. 8 kg of this pulverized product was put into the primary pyrolysis tank 2 having a height of about 65 cm from the raw material inlet 1 and heated and melted. When the temperature was raised at 10 ° C./minute, a gaseous product due to thermal decomposition started to be generated at about 310 ° C. and moved to the secondary thermal decomposition tank 3. The liquid temperature in the primary pyrolysis tank was maintained near 350 ° C and the reaction was continued at LHSV 0.9-1.3. The heating was performed with a gas burner provided at the bottom. The secondary pyrolysis tank 3 was filled with about 500 g of H type ZSM-5 having a particle size of about 3 mm. The produced gas was introduced into the cooler from the upper portion of the secondary thermal decomposition tank 3 to obtain a liquid product.

The heating was stopped when the liquid temperature in the first thermal decomposition tank 2 reached 370 ° C. The same operation as above was repeated twice more in the state where a part of the residue remained in the primary thermal decomposition tank.

As a result of three operations, the yield of the liquid product was 91%, and the others were gas (about 5%) and residue (about 4%).

As a result of analyzing the liquid product, benzene 3%, toluene
13%, 50% C8 consisting mainly of ethylbenzene, and the balance was mainly other aromatic hydrocarbons and partly paraffinic hydrocarbons.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of an apparatus used for carrying out the method of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C07C 5/22 15/02 C08J 11/10 CET // C07B 61/00 300 (72) Inventor Saito Kiyoshi, 17-21, Nijokanto Nijo 17-2, Toyohira-ku, Sapporo, Hokkaido (72) Inventor, Takashi Fukuda 2-17-1, Tsukikanto Nijo 17-2, Toyohira-ku, Sapporo, Hokkaido In the laboratory (72) Satoshi Suzuki Satoshi Nijo 17-2-1, Tsukikanto, Toyohira-ku, Sapporo, Hokkaido Inside the Hokkaido Industrial Development Laboratory (72) Inventor Masakazu Abe 88 Uekino Ueno, Antomi-cho, Shishiwa-gun, Hyogo Inside Fujitec Co., Ltd. (72) Inventor Toshio Hirota 791-51 Kanagaya, Asahi-ku, Yokohama-shi, Kanagawa Examiner Makiko Iwase (56) References 51-89504 (JP, A) JP Akira 60-49086 (JP, A) JP Akira 49-41322 (JP, A) JP Akira 50-5335 (JP, A)

Claims (6)

[Claims] 1. A polystyrene waste is melted, and the melt is heated to be thermally decomposed in a liquid phase.
A process for treating polystyrene waste, which comprises subjecting a zeolite packed bed having a constraint coefficient in the range of ~ 12 to catalytic conversion at a temperature in the range of 200 to 400 ° C to produce and obtain an aromatic hydrocarbon oil. 2. A process according to claim 1, wherein the melt liquid phase pyrolysis temperature is in the range of 200 to 450 ° C. 3. The method according to claim 1, wherein the zeolite is ZSM-5. 4. The method according to claim 1, wherein the particle size of the zeolite is 0.1 to 10 mm. 5. The method according to claim 1, wherein the polystyrene waste is expanded polystyrene. 6. The method according to claim 5, wherein the expanded polystyrene waste is defoamed, ground and then melted.