JPH1192769A - Method for liquefying plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently liquefy a plastics mixture, esp. one contg. polyolefin and polystyrene by thermally decomposing the mixture in the presence of a solid acid catalyst previously brought into contact with a hydrocarbon gas. SOLUTION: A mixture of thermoplastic resins or thermosetting resins contg. polyolefin and polystyrene as the main ingredients is liquefied by the thermal decomposition at from room temp. to 200 deg.C for 1 min to 30 hr in the presence of a solid acid catalyst which has been brought into contact with a hydrocarbon gas (e.g. an aliph. satd. hydrocarbon, an aliph. unsatd. hydrocarbon, or an arom. hydrocarbon) or with a decomposition gas generated in the thermal decomposition of plastics. The thermal decomposition is pref. conducted at 150-600 deg.C for 0.1 min to 5 hr, and the amt. of the catalyst used is pref. 0.01-20 wt.% of the plastics mixture. An oily product obtd. by the thermal decomposition can be used as a fuel, a raw material, etc., and the catalyst can be contained in the product or can be separated, recovered, and reused.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for converting a plastic, particularly a mixed plastic containing polyolefin and polystyrene, into oil by subjecting it to thermal decomposition to obtain an oily substance.

[0002]

2. Description of the Related Art As a method for thermally decomposing plastic to oil, there is known a method in which a mixture of plastic and a solid acid catalyst such as silica-alumina, zeolite or the like is heated from room temperature to an oil-forming temperature (for example, see, for example). JP-A-48-967
Nos. 48-43075 and 59-111815). Such a solid acid catalyst is said to be highly effective in oiling plastics containing polyolefins such as polyethylene and polypropylene.

[0003] However, in the conventional method, the catalytic activity was not sufficient, and the oiling rate was insufficient. In particular, when a mixed plastic in which polystyrene is contained in a plastic containing a polyolefin such as polyethylene or polypropylene is oiled, the activity of the catalyst is reduced, so that the oil cannot be efficiently oiled.

Japanese Patent Application Laid-Open No. 49-20284 discloses that, as a catalyst, Kanuma soil is mixed with polyethylene, polystyrene, polypropylene and a mixed plastic having a vinyl chloride ratio of 3/3/2/2, and then heated to oil. When you do
It is shown that the activity of the catalyst is reduced as compared with the case of oiling polyethylene or polypropylene alone. The catalyst with reduced activity has carbon adhered to its surface, and a method for regenerating the deteriorated catalyst by firing at 600 ° C. is described.

[0005] On the other hand, Japanese Patent Application Laid-Open No. 6-220458 discloses that, when polystyrene is converted into oil, the melt is thermally decomposed to separate and remove gas components, and then the oil is gasified in a heating furnace to contact the catalyst. A method for reducing the weight is shown. In this method, a light gas component generated in the first thermal decomposition is removed, thereby preventing the gas component from being further decomposed into a lighter component by the catalyst and reducing the production amount of oil. For this reason, no consideration is given to a reduction in the activity of the catalyst during the oiling of the mixed plastic.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for liquefying a plastic which can be efficiently liquefied,
In particular, it is an object of the present invention to propose a method for oiling plastics, which can efficiently oilify mixed plastics containing polystyrene in addition to polyolefin.

[0007]

SUMMARY OF THE INVENTION The present invention relates to the following method for liquefying plastic. 1) A method for liquefying a plastic, which comprises contacting a solid acid catalyst with a hydrocarbon gas in advance in a method for thermally decomposing a plastic in the presence of a solid acid catalyst. (2) The method according to the above (1), wherein the hydrocarbon gas to be brought into contact with the solid acid catalyst is a gas generated by thermal decomposition of the plastic. (3) The method according to the above (1) or (2), wherein the solid acid catalyst is a silica-alumina catalyst. (4) The method according to any one of the above (1) to (3), wherein the plastic is a mixed plastic containing polyolefin and polystyrene.

[0008] In the present invention, the plastic to be oiled is not particularly limited, and may be either a thermoplastic resin or a thermosetting resin, but those containing a polyolefin, particularly those containing a polyolefin as a main component. Suitable as. Examples of the thermoplastic resin include polyolefin (PO) such as polyethylene (PE) and polypropylene (PP), polystyrene (PS), high-impact polystyrene (HIPS), ABS resin, ethylene-vinyl acetate copolymer resin (EVA), Vinyl chloride (PV
C), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyamide (PA,
Nylon) and polycarbonate (PC). The thermosetting resin is a phenolic resin,
Melamine resin, urea resin, alkyd resin, polyurethane (PU) and the like can be mentioned. These plastics may be used alone or as a mixture of two or more.

Among the above-mentioned plastics, polyolefins such as polyethylene and polypropylene and mixtures thereof, or polyolefins such as these,
Mixtures of plastics (mixed plastics) containing, by weight, preferably 70-90% by weight and polystyrene 40-1% by weight, preferably 30-10% by weight, are suitable.

[0010] Plastics to be oiled include waste plastics contained in municipal waste, industrial waste and the like. Such waste plastics are generally discharged in a state in which various plastics are mixed, but such mixed plastics may be sorted out in advance, or oiled without being sorted.

[0011] Plastics to be oiled include waxes, rubbers, elastomers and the like in addition to those classified as so-called resins. Specific examples thereof include the following. -Ethylene waxy polymer or grease-like polymer. -A propylene-based wax-like polymer or grease-like polymer, for example, atactic polypropylene. A synthetic rubber, for example, ethylene-propylene copolymer rubber (EPM), ethylene-propylene-non-conjugated diene copolymer rubber (EPDM), styrene-butadiene copolymer rubber (SBR), butadiene-acrylonitrile copolymer rubber (NBR), Chloroprene rubber (CR), polyisoprene rubber (IR), butyl rubber (IIR), polybutadiene rubber (BR) and cross-linked products (vulcanizates) thereof, thermoplastic elastomers, such as ethylene-propylene-non-conjugated diene copolymer rubber / Partially crosslinked products of polyethylene compositions, hydrides of styrene-butadiene copolymers and synthetic “hydrocarbon resins” such as “petroleum resins”.

As the solid acid catalyst used in the present invention, any solid acid catalyst having an action of promoting the lightening (low molecular weight) of polyolefin in a heated state can be used without limitation. Examples of the solid acid catalyst used in the present invention include the following: ◆ crystalline silica-alumina, amorphous silica-alumina,
◆ Alumina oxide (alumina), silicon oxide (silica); ◆ Silica magnesia, zinc oxide, bauxite; ◆ Natural soil (acid clay, activated clay, Kanuma clay pumice, Imaichi pumice, Shichihonzakura pumice, Akadama clay, volcanic ash, (Moka pumice, Yugi pumice); ◆ Heavy metal oxides such as iron oxide, copper oxide, nickel oxide, molybdenum oxide and the like.

In the present invention, among the solid acid catalysts described above,
A silica-alumina solid acid catalyst is preferred. The catalyst is a catalyst mainly composed of silica / alumina, specifically, crystalline silica / alumina (zeolite), amorphous or low-crystalline synthetic silica / alumina, amorphous minerals such as allophane, Examples include dealuminated Y-type zeolites.

[0014] Silica-alumina is a composite oxide of silica and alumina, also called aluminosilicate, which includes naturally occurring clays, minerals, and synthetic zeolites. In the present invention, in particular, amorphous silica-alumina is used. And SiO2 / Al2O3 (weight ratio) is 90/10 to 40/6
0; amorphous synthetic silica-alumina; allophane; natural silica-alumina selected from acid clay and activated clay.

The above-mentioned allophane (allophane or allophane) is also referred to as “allophen”, is a hydrated silicate mineral of aluminum, and has a composition formula p
SiO2.qAl2O3.rH2O (p: q = 1-2: 1)
An amorphous or latent crystalline compound represented by This allophane is contained in soil derived from volcanic ash, and can be used in either amorphous or hollow spherical form. Specific examples of such allophanes include Kanuma soil, Imaichi pumice, Ishikigawa pumice, Hanno pumice, Hayaki pumice, Shichinohe pumice,
Moka pumice, Iijima miso soil, Otani clay, etc. Commercial products such as Secard (Allophane, trademark, manufactured by Shinagawa Kasei) can also be used, and these allophane can be obtained at low cost.

Acid clay is a white clay mainly containing montmorillonite, and is a mineral exhibiting acidity due to base unsaturation.
Activated clay is a mineral whose activity is enhanced by acid treatment of clay mainly containing montmorillonite. Zeolite is Si
A mineral having a three-dimensional crystal structure of O2 and Al2O3,
There are naturally occurring and synthetic ones, and both can be used.

In order to convert the plastic into oil by the method of the present invention, the solid acid catalyst is exposed to hydrocarbon gas in advance, and then the plastic is catalytically pyrolyzed. The contact temperature of the hydrocarbon gas is from room temperature to 200 ° C, preferably from room temperature to 100 ° C. The contact time is usually 1 minute to 30 hours, preferably 5 minutes to 20 hours.

The hydrocarbon gas includes ethane, propane,
Any of aliphatic saturated hydrocarbons such as butane and hexane, aliphatic unsaturated hydrocarbons such as ethylene, propylene, butene, hexene, octene and decene, and aromatic hydrocarbons such as benzene, toluene and xylene can be used. These may be used alone or in combination for contact exposure.

Further, a decomposition gas generated by thermal decomposition of the plastic may be exposed to contact. Examples of the decomposed gas include a decomposed gas generated by thermally decomposing a system made of a polyolefin such as polyethylene, polypropylene, and polybutene, or a plastic made of a hydrocarbon such as polystyrene, alone or in combination. The decomposition temperature is usually from 150 to 600C, preferably from 250 to 500C. In generating a decomposition gas by thermal decomposition, the thermal decomposition may be performed in the presence of a solid acid catalyst or may be performed without using a solid acid catalyst.

When the solid acid catalyst is brought into contact with the pyrolysis gas, the cracked gas previously collected may be brought into contact with the solid acid catalyst. For example, the solid acid catalyst may be placed at the inlet of the gas collector. It is preferable that the gas is collected and the solid acid catalyst is brought into contact with the solid acid catalyst at the same time, since the time for adjusting the catalyst of the present invention can be reduced.

In order to convert plastic into oil by the method of the present invention, the plastic is contacted in the presence of the solid acid catalyst which has been previously contacted with the hydrocarbon gas or a cracking gas generated by thermal decomposition of the plastic. Decomposes thermally. As a result, the plastic oils and an oil is obtained. Decomposition temperature is 150 to 600 ° C, preferably 250 to
It is desirable to set the reaction time to 500 ° C. and the reaction time to 0.1 min to 5 hr. The atmosphere of the reaction system may be any atmosphere as long as the reaction is not hindered. For example, the decomposition can be performed in a nitrogen atmosphere. The amount of the solid acid catalyst used is 0.01 to 20% by weight, preferably 0.1 to 20% by weight based on the weight of the plastic.
It is desirable that the content be 1 to 10% by weight.

The reactor used for the thermal decomposition of the plastic may be any type such as a tank type, a screw type, a pipe type and the like. As a specific example of the cracking reaction device, a plastic to be oiled is placed at 300 to 600 ° C., preferably 400 to 5 ° C. in a tubular cracking furnace provided with a conveying screw in the tube.
There is an apparatus provided with a mechanism for heating to 00 ° C. Since this type of decomposition reactor has a continuous decomposition capability, it is suitable for a treatment facility where a large amount of plastic is constantly (continuously) accumulated.

As described above, in the method of the present invention, the plastic can be efficiently converted to oil by contacting the plastic with a solid acid catalyst which has been subjected to a gas contact treatment in advance and thermally decomposing the plastic. In particular, even when a mixed plastic containing polystyrene in addition to polyolefin is oiled, the oil can be efficiently oiled.

The oil obtained by the method of the present invention can be used for fuels, raw materials, and any other uses.
The catalyst may be mixed with the oily substance, but may be separated and recovered for reuse.

[0025]

According to the method for oiling plastics of the present invention, the plastics are thermally decomposed in the presence of a solid acid catalyst which has been previously contacted with a hydrocarbon gas. Even if it is a mixed plastic containing polyolefin and polystyrene, oiling can be efficiently performed.

[0026]

Next, an embodiment of the present invention will be described. Example 1 As a solid acid catalyst, silica-alumina [catalyzed silica alumina HA manufactured by Catalyst Chemical Industry Co., Ltd., crystallinity = 0]
%, Weight ratio of SiO2 / Al2O3 = 71/29, surface area (BET) = 510 m <2> / g], and then pulverized to separate particles having a particle size of 18 to 50 mesh. The resulting catalyst is abbreviated as HA catalyst.

Toluene was heated to 60 ° C., and 0.3 g of the HA catalyst was put into a system in which the inside of the system was saturated with toluene vapor, and brought into contact with the toluene vapor for 3 hours. This operation increased the weight of the HA catalyst by 7% when used in the pyrolysis reaction. Next, 10 g of a mixed plastic (weight ratio of PE / PP / PS = 50/20/30) containing high-density polyethylene, polypropylene and polystyrene was put into a quartz reactor having an internal volume of 200 ml with a distillate receiver, and the inside of the reactor was filled. Was replaced with nitrogen. The mixture was heated to 350 ° C. under normal pressure and melted, and the entire amount of the above gas-contacted HA catalyst (0.302 g) was added.
Thereafter, the temperature was raised to 430 ° C. Immediately, oily decomposition products began to distill, 8 ml of oil distilling out in 6 minutes. 8ml
The average distillation rate before distillation is 1.33 ml / min
It is. The amount of oil distilled as a result of the reaction was 6.68 g, and the amount of residue remaining in the reactor was 2.67 g.

Example 2 A mixed plastic containing high-density polyethylene, polypropylene and polystyrene was placed in a 200 ml quartz reactor equipped with a distillate receiver in which 0.3 g of HA catalyst was set at the inlet of a Tedlar bag gas collector. (PE / PP / PS
(Weight ratio = 50/20/30) of 10 g, and the inside of the reactor was replaced with nitrogen. After heating and melting at 350 ° C. at normal pressure, 0.3 g of HA catalyst was added, and then the temperature was raised to 430 ° C. When 8 ml of distillate was obtained, the HA catalyst set at the inlet of the gas collector was removed. 350 ml of the decomposed gas was collected in the collector for 8 minutes. This operation increased the weight of the HA catalyst by 13% when used in the pyrolysis reaction. Next, 10 g of the same mixed plastic as in Example 1 was heated and melted at 350 ° C., and the entire amount (0.338 g) of the gas-treated HA catalyst was added. Thereafter, the temperature was raised to 430 ° C. Immediately, oily decomposition products began to distill, 8 ml of oil distilling out in 5 minutes. The average distillation rate until 8 ml is distilled is 1.60 ml / min. The amount of oil distilled as a result of the reaction was 6.80 g, and the amount of residue remaining in the reactor was 2.55 g.

Example 3 A mixed plastic containing high-density polyethylene, polypropylene, polystyrene and ABS resin (PE / PP / P
(S / ABS weight ratio = 50/20/30/5) 10.5
g of the catalyst was melted by heating to 350 ° C., and then 3.036 g of an HA catalyst prepared in advance by gas contact in the same manner as in Example 2 was added, and then the temperature was raised to 430 ° C. Immediately, oily decomposition products began to distill, 8 ml of oil distilling in 33.4 minutes. The average distillation speed until 8ml is distilled is 0.24m
1 / min. 6.64 g of oil distilled as a result of the reaction,
The amount of residue remaining in the reactor was 3.25 g.

Comparative Example 1 10 g of the same mixed plastic as in Example 1 was added at normal pressure to 35 g.
After heating and melting to 0 ° C, 0.3 g of the HA catalyst was added, and then the temperature was raised to 430 ° C. Immediately, oily decomposition products began to distill, and 8 ml of oil distilled over in 6.7 minutes. The average distillation rate until 8 ml is distilled is 1.19 ml / min. The amount of oil distilled as a result of the reaction was 6.72 g, and the amount of residue remaining in the reactor was 2.75 g.

Comparative Example 2 10.5 g of the same mixed plastic as in Example 3 was heated and melted at 350 ° C. under normal pressure, and 0.3 g of an HA catalyst was added.
Thereafter, the temperature was raised to 430 ° C. Immediately, oily decomposition products began to distill, 8 ml of oil distilling out in 48 minutes. 8m
The average distillation rate until distillation is 0.167 ml / m
in. The amount of oil distilled as a result of the reaction was 6.69 g, and the amount of residue remaining in the reactor was 3.11 g.

From the above results, it can be seen that the example in which the solid acid catalyst prepared by preliminarily subjecting the mixed plastic to gas contact treatment and then thermally decomposed was subjected to the solid acid catalyst not subjected to gas contact treatment with the mixed plastic. It can be seen that the oil-promoting effect is higher than that of the comparative example in which thermal decomposition was performed.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Daisuke Fukuoka 6-1-2, Waki, Waki-cho, Kuga-gun, Yamaguchi Prefecture Inside Mitsui Petrochemical Industry Co., Ltd.

Claims (4)

[Claims] 1. A method for thermally decomposing a plastic in the presence of a solid acid catalyst, wherein the solid acid catalyst is brought into contact with a hydrocarbon gas in advance. 2. The method according to claim 1, wherein the hydrocarbon gas to be brought into contact with the solid acid catalyst is a gas generated by thermal decomposition of the plastic. 3. The method according to claim 1, wherein the solid acid catalyst is a silica-alumina catalyst. 4. The method according to claim 1, wherein the plastic is a mixed plastic containing polyolefin and polystyrene. [0001]