JP7304615B2 - Solid catalyst, method for producing same, method for producing oil - Google Patents

Description

TECHNICAL FIELD The present invention relates to a solid catalyst, a method for producing the same, and a method for producing an oil.

Development of a method for decomposing polyolefin plastics such as polyethylene into oil and reusing them as liquid fuels and the like is underway. Regarding the method of converting such polyolefin plastics to oil, the development of catalysts suitable for oil conversion is underway.

For example, a method of hydrocracking squalane and alkane using a ruthenium (Ru) catalyst is known (see, for example, Non-Patent Document 1). A method of producing algae-derived gasoline fuel using a ruthenium (Ru) catalyst is also known (see, for example, Non-Patent Document 2). Furthermore, a method for producing squalane and algae-derived branched hydrocarbons having 30 carbon atoms using a ruthenium (Ru) catalyst is known (see, for example, Non-Patent Document 3).

Regioselectivity and Reaction Mechanism of Ru-Catalyzed Hydrogenolysis of Squalane and Model Alkanes, Yoshinao Nakagawa, Shin-ichi Oya, Daisuke Kanno, Yoshi ke Nakaji, Masazumi Tamura, and Keiichi Tomishige, Chem Sus Chem 2017, 10, 189-198, DOI: 10 .1002/cssc. 201601204 Production of Gasoline Fuel from Alga-Derived Botryococcene by Hydrogenolysis over Ceria-Supported Ruthenium Catalyst, Yosuke Nakaji, Shin-ichi Oya, Hideo Watanabe, Makoto M.; Watanabe, Yoshinao Nakagawa, Masazumi Tamura, and Keiichi Tomishige, Chem Cat Chem 2017, 9, 2701-2708, DOI: 10.1002/cctc. 201700200 Catalytic Production of Branched Small Alkanes from Biohydrocarbons, Shin-ichi Oya, Daisuke Kanno, Hideo Watanabe, Masazumi Tamura, Yoshinao Nakagawa, and Keiichi Tomishige, Chem Sus Chem 2015, 8, 2472-2475, DOI: 10.1002/cssc. 201500375

However, conventional catalysts have problems in that collection and regeneration after completion of the reaction are complicated, and the reaction temperature during the catalytic reaction is high (400° C. or higher).

The present invention has been made in view of the above circumstances, and is a solid catalyst that can be easily recovered and regenerated after the completion of the reaction and can lower the reaction temperature during the catalytic reaction than before, and a method for producing the same. An object of the present invention is to provide a method for producing an oil.

The present invention has the following aspects.
[1] A solid catalyst used for a decomposition reaction of polyolefin, comprising a carrier made of a metal oxide and ruthenium supported on the carrier, and having a specific surface area of 10 m ² /g or more and 1000 m ² /g or less. wherein the metal oxide is at least one selected from the group consisting of cerium oxide, silicon oxide, magnesium oxide, titanium oxide and zirconium oxide.
[2] The solid catalyst according to [1], wherein the supported amount of ruthenium is 1% by mass or more and 30% by mass or less .
[3] A method for producing a solid catalyst used in a decomposition reaction of polyolefin, comprising the steps of calcining a metal oxide at 600° C. or more and 1500° C. or less in an air atmosphere; and heat-treating at 200° C. or higher and 1000° C. or lower in a nitrogen atmosphere, wherein the metal oxide is at least one selected from the group consisting of cerium oxide, silicon oxide, magnesium oxide, titanium oxide and zirconium oxide. A method for producing a solid catalyst that is a seed .
[ 4 ] A method for producing an oily substance, comprising the steps of bringing the solid catalyst according to [1] or [2] into contact with a plastic having a melting point of 250°C or lower, and heat-treating the plastic at 100°C or higher under hydrogen .

According to the present invention, it is possible to provide a solid catalyst, a method for producing the same, and a method for producing an oily substance, which are easy to recover and regenerate after the completion of the reaction, and which can lower the reaction temperature during the catalytic reaction. can.

In Experimental Example 20, the relationship between the reaction time and the conversion rate, the relationship between the reaction time and the yield of the gas having 1 to 4 carbon atoms, the relationship between the reaction time and the yield of the oily substance having 5 to 21 carbon atoms, the reaction time and the carbon FIG. 2 is a diagram showing the relationship between the yield of oils having a number of 22-45 and the relationship between the reaction time and the yield of oils having 15-45 carbon atoms. FIG. 10 is a diagram showing the results of analyzing the recovered gas (vapor phase) and liquid phase using a gas chromatograph/flame ionization detector (GC-FID) for each predetermined reaction time in Experimental Example 20. FIG. 2 is a diagram showing the results of analyzing the gas (vapor phase) and liquid phase recovered after the completion of the reaction in Experimental Examples 1 and 21 using a gas chromatograph/flame ionization detector (GC-FID). FIG. 13 shows the results of ¹³ C NMR measurement on the sample of Experimental Example 22; FIG. 13 shows the results of ¹³ C NMR measurement of the sample of Experimental Example 23. FIG. FIG. 10 is a diagram showing the results of X-ray diffraction (XRD) measurement of the solid catalyst (Ru/CeO ₂ ) before and after the decomposition reaction in Experimental Example 28; FIG. 10 is a diagram showing the results of X-ray diffraction (XRD) measurement of a solid catalyst (Ru/CeO ₂ ) in Experimental Example 30; FIG. 8 is an enlarged view of a part of FIG. 7;

Embodiments of the solid catalyst of the present invention, the method for producing the same, and the method for producing an oily product will be described.
It should be noted that the present embodiment is specifically described for better understanding of the gist of the invention, and does not limit the invention unless otherwise specified.

[Solid catalyst]
The solid catalyst of the present embodiment contains a carrier made of a metal oxide and ruthenium (Ru) supported on the carrier, and has a specific surface area of 10 m ² /g or more and 1000 m ² /g or less.
The specific surface area of the solid catalyst of the present embodiment is 10 m ² /g or more and 1000 m ² /g or less, preferably 10 m ² /g or more and 500 m ² /g or less, and 20 m ² /g or more and 300 m ² /g or less. is more preferable.
If the specific surface area is less than 10 m ² /g, the activity of the solid catalyst is lowered. On the other hand, when the specific surface area exceeds 1000 m ² /g, the activity of the solid catalyst is lowered.

The specific surface area (unit: m ² /g) of the solid catalyst of the present embodiment is the BET specific surface area determined by the BET method.
Examples of the method for measuring the specific surface area of the solid catalyst include the BET method using a fully automatic specific surface area measuring device (trade name: Gemini VII2360, manufactured by Shimadzu Corporation).

In the solid catalyst of the present embodiment, the amount of ruthenium supported is preferably 1% by mass or more and 30% by mass or less, and 3% by mass or more and 10% by mass or less, out of 100% by mass of the total mass of the solid catalyst. is more preferred.
If the supported amount of ruthenium is 1% by mass or more, the solid catalyst is excellent in activity. On the other hand, when the supported amount of ruthenium is 30% by mass or less, the solid catalyst exhibits excellent activity, and the gas component does not increase in the decomposition of plastic using the solid catalyst.

In the solid catalyst of the present embodiment, the supported amount of ruthenium is calculated from the theoretical charged amount.

In the solid catalyst of the present embodiment, the metal oxide is selected from the group consisting of cerium oxide (CeO ₂ ), silicon oxide (SiO ₂ ), magnesium oxide (MgO), titanium oxide (TiO ₂ ) and zirconium oxide (ZrO ₂ ). At least one selected is preferable, and cerium oxide (CeO ₂ ) is more preferable from the viewpoint of selectivity. These metal oxides may be used individually by 1 type, and may be used in combination of 2 or more type.

The solid catalyst of the present embodiment is brought into contact with a plastic having a melting point of 250° C. or less, and the plastic is heat-treated under hydrogen to decompose the plastic and produce an oil such as wax or lubricating oil. It is suitably used for the production method of

When the solid catalyst of the present embodiment is used in the decomposition reaction of plastics, it is easy to recover and regenerate after the completion of the reaction, and the reaction temperature during the catalytic reaction can be made lower than before. That is, the solid catalyst of the present embodiment can be easily recovered by filtration after being used for the decomposition reaction of plastics. In addition, since the solid catalyst of the present embodiment is hardly deteriorated even when used in a plastic decomposition reaction, it can be used again as a plastic decomposition catalyst by washing with an organic solvent after recovery. Furthermore, since the solid catalyst of the present embodiment can lower the reaction temperature during the catalytic reaction, it is possible to reduce the energy (calorie) required for the plastic decomposition reaction.

[Method for producing solid catalyst]
The method for producing the solid catalyst of the present embodiment is a method for producing the above-described solid catalyst of the present embodiment.
The method for producing a solid catalyst of the present embodiment includes a step of calcining a metal oxide at 600° C. or higher and 1500° C. or lower in an air atmosphere (hereinafter referred to as “first step”); and ruthenium in a nitrogen atmosphere at 200° C. or higher and 1000° C. or lower (hereinafter referred to as “second step”).

In the first step, the temperature for sintering the metal oxide is 600° C. or higher and 1500° C. or lower, preferably 600° C. or higher and 1000° C. or lower, in an air atmosphere.
If the temperature for calcining the metal oxide is less than 600°C, the activity of the solid catalyst is lowered. On the other hand, when the temperature for calcining the metal oxide exceeds 1500° C., the activity and selectivity of the solid catalyst are lowered.

In the first step, the time for firing the metal oxide within the above temperature range is preferably 0.5 hours or longer, more preferably 1 hour or longer.
If the time for calcining the metal oxide is less than 0.5 hours, the crystallinity of the metal oxide is lowered and the activity of the solid catalyst is lowered.

The method (means) for firing the metal oxide is not particularly limited, but examples thereof include a method of firing in a firing furnace and a method of firing in a tubular flow device.

As the metal oxide, at least one selected from the group consisting of cerium oxide (CeO ₂ ), silicon oxide (SiO ₂ ), magnesium oxide (MgO), titanium oxide (TiO ₂ ) and zirconium oxide (ZrO ₂ ). It is preferable to use These metal oxides may be used individually by 1 type, and may be used in combination of 2 or more type.

In the second step, the method of mixing the metal oxide and ruthenium baked in the first step is not particularly limited, but for example, Ru(NO) (NO ₃ ) _3-x (OH) _x is mixed, the mixture is heated under a nitrogen atmosphere, dried, and then heat-treated under a nitrogen atmosphere.

In the second step, the temperature for heat-treating the mixture of metal oxide and ruthenium in a nitrogen atmosphere is 200° C. or higher and 1000° C. or lower, preferably 300° C. or higher and 800° C. or lower.
When the mixture is heat-treated at a temperature lower than 200°C, the activity of the solid catalyst is lowered. On the other hand, when the mixture is heat-treated at a temperature exceeding 1000° C., the activity and selectivity of the solid catalyst are lowered.

In the second step, the time for heat-treating the mixture within the above temperature range is preferably 0.5 hours or longer, more preferably 1 hour or longer.
If the mixture is heat treated for less than 0.5 hours, insufficient catalyst formation will result.

The method (means) for heat-treating the mixture is not particularly limited, but examples thereof include heat-treating in a kiln and heat-treating in a tubular flow device.

According to the method for producing a solid catalyst of the present embodiment, the metal oxide is calcined at 600° C. or more and 1500° C. or less in an air atmosphere, and the mixture of the calcined metal oxide and ruthenium is heated to 200° C. or more in a nitrogen atmosphere. Since the heat treatment is performed at 1000° C. or less, a solid catalyst containing a metal oxide carrier and ruthenium supported on the carrier and having a specific surface area of 10 m ² /g or more and 1000 m ² /g or less is obtained.

[Method for producing oil]
The method for producing an oily product of the present embodiment includes the steps of bringing the solid catalyst of the present embodiment into contact with plastic having a melting point of 250° C. or lower and heat-treating the plastic at 100° C. or higher under hydrogen.

The plastic in the method for producing an oily substance of the present embodiment is not particularly limited as long as it has a melting point of 250° C. or less. Examples include vinyl chloride (PVC), polyethylene terephthalate (PET), polycarbonate (PC), polyamide (PA), epoxy resin, and the like. These plastics make up the majority of waste plastics. Among these plastics, polyolefins, which are hydrocarbon plastics, are preferred.

In the step of heat-treating the plastic, the amount of the solid catalyst added to 100 parts by mass of the plastic is preferably 0.01 parts by mass or more and 10 parts by mass or less, more preferably 0.1 parts by mass or more and 5 parts by mass or less. preferable.
If the amount of solid catalyst added is less than 0.01 parts by mass, sufficient catalytic activity cannot be obtained. On the other hand, if the amount of the solid catalyst added exceeds 10 parts by mass, the cost of the catalyst becomes very high.

In the step of heat-treating the plastic under hydrogen, the temperature at which the plastic is heat-treated under hydrogen in an air atmosphere is 100°C or higher, preferably 150°C or higher, and more preferably 160°C or higher and 250°C or lower. .
If the temperature for heat-treating the plastic under hydrogen is less than 100°C, sufficient catalytic activity cannot be obtained.
Note that heat treatment under hydrogen means heat treatment under hydrogen pressurization conditions.

In the step of heat-treating the plastic under hydrogen, the time for heat-treating the plastic under hydrogen within the above temperature range is preferably 0.1 hour or more and 100 hours or less, and preferably 1 hour or more and 72 hours or less. more preferred.

According to the method for producing an oily substance of the present embodiment, the solid catalyst of the present embodiment is brought into contact with a plastic having a melting point of 250° C. or lower, and the plastic is hydrothermally treated at 100° C. or higher. It is possible to produce oils such as

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to experimental examples, but the present invention is not limited to the following experimental examples.

[Experimental example 1]
(Production of solid catalyst)
Cerium oxide (CeO ₂ ) (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) was calcined at 873 K (600° C.) for 3 hours in an air atmosphere.
0.95 g of cerium oxide after firing and 3.33 g of Ru(NO)(NO ₃ ) _3-x (OH) _x (ruthenium content: 1.5% by mass, manufactured by Aldrich) as a ruthenium (Ru) precursor solution The mixture is dried at 383 K (110) ° C. for 12 hours under a nitrogen atmosphere, and then heat-treated at 573 K (300 ° C.) for 1 hour under an air atmosphere to obtain 5 mass of ruthenium. % of solid catalyst (Ru/CeO ₂ ) was obtained. The solid catalyst (Ru/CeO ₂ ) is hereinafter referred to as Ru/CeO ₂ catalyst.

(decomposition reaction)
100 mg of the resulting Ru/CeO ₂ catalyst, 3.4 g of low density polyethylene (number average molecular weight Mn=1700) and a glass stirrer tip were charged into the reactor.
Then, after the inside of the reaction vessel was replaced with hydrogen three times, hydrogen was introduced into the reaction vessel so that the internal pressure of the reaction vessel was 6 MPa, and the reaction vessel was sealed.
Next, the temperature in the reaction vessel is raised to 513 K (240° C.) over 1 hour, and 1 hour after the start of heating, that is, when the temperature in the reaction vessel (reaction temperature) reaches 513 K (240° C.) was taken as a reaction time of 0 hours (at the start of the reaction).
During the reaction, the Ru/ _CeO2 catalyst and the low-density polyethylene were stirred by rotating a glass stirrer tip at a speed of 450 rpm. The reaction time (time to continue stirring and time to maintain the reaction temperature) was 5 hours.
After the reaction time (5 hours) had passed, the reaction vessel was cooled to room temperature using a water bath.
From the reaction vessel after cooling, the entire amount of gas (vapor phase) was taken out into a gas bag. After that, 80 μL of dichloromethane was introduced as an internal standard into the gas bag containing the gas.
Further, from the reaction vessel after cooling, the liquid phase was recovered using mesitylene in an autoclave charged with 100 mg of 9,10-dihydroanthracene as an internal standard.
The recovered gas (gas phase) and liquid phase were analyzed using a gas chromatograph/flame ionization detector (GC-FID) (trade name: GC-2014, manufactured by Shimadzu Corporation). Table 1 shows the results.
Further, a solid was recovered from the reaction vessel after cooling by filtration under reduced pressure, and the mass of the solid was measured.

[Experimental example 2]
(Production of solid catalyst)
The experiment was carried out except that 0.95 g of cerium oxide after firing and 0.58 g of Ir(NO ₃ ) ₄ (iridium content 8.63% by mass, manufactured by Furuya Metal Co., Ltd.), which is an iridium (Ir) precursor solution, were used. Analogously to Example 1, an Ir/CeO ₂ catalyst containing 5% by weight of iridium was obtained.

(decomposition reaction)
Low-density polyethylene was decomposed in the same manner as in Experimental Example 1 except that Ir/CeO ₂ was used as a solid catalyst and the reaction temperature was 513 K (240° C.) or 533 K (260° C.). When the reaction temperature was 260°C, the reaction time was 24 hours. Table 1 shows the results.

[Experimental example 3]
(Production of solid catalyst)
Except that 0.95 g of cerium oxide after firing and 0.55 g of Rh(NO ₃ ) ₃ (rhodium content 9.16% by mass, manufactured by Wako Pure Chemical Industries, Ltd.), which is a rhodium (Rh) precursor solution, were used. A Rh/CeO ₂ catalyst containing 5% by mass of rhodium was obtained in the same manner as in Experimental Example 1.

(decomposition reaction)
Low-density polyethylene was decomposed in the same manner as in Experimental Example 2 except that Rh/CeO ₂ was used as a solid catalyst and the reaction temperature was 513 K (240° C.) or 533 K (260° C.). Table 1 shows the results.

[Experimental example 4]
(Production of solid catalyst)
0.95 g of cerium oxide after firing and 1.10 g of Pt(NH ₃ ) ₂ (NO ₂ ) ₂ (platinum content 4.564% by mass, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.), which is a platinum (Pt) precursor solution, A Pt/CeO ₂ catalyst containing 5% by mass of platinum was obtained in the same manner as in Experimental Example 1, except that it was used.

(decomposition reaction)
Low-density polyethylene was decomposed in the same manner as in Experimental Example 2 except that Pt/CeO ₂ was used as a solid catalyst and the reaction temperature was 513 K (240° C.) or 533 K (260° C.). Table 1 shows the results.

[Experimental example 5]
(Production of solid catalyst)
Except that 0.95 g of cerium oxide after firing and 0.99 g of Pd(NO ₃ ) ₂ (palladium content: 5.03% by mass, manufactured by NE Chemcat), which is a palladium (Pd) precursor solution, were used. A Pd/CeO ₂ catalyst containing 5% by mass of palladium was obtained in the same manner as in Experimental Example 1.

(decomposition reaction)
Low-density polyethylene was decomposed in the same manner as in Experimental Example 2 except that Pd/CeO ₂ was used as a solid catalyst and the reaction temperature was 513 K (240° C.) or 533 K (260° C.). Table 1 shows the results.

[Experimental example 6]
(Production of solid catalyst)
Same as Experimental Example 1, except that 0.95 g of cerium oxide after firing and 0.19 g of Cu(NO ₃ ) _{2.3H 2} O (manufactured by Wako Pure Chemical Industries, Ltd.), which is a copper (Cu) precursor solution, were used. Similarly, a Cu/CeO ₂ catalyst containing 5% by weight of copper was obtained.

(decomposition reaction)
Low-density polyethylene was decomposed in the same manner as in Experimental Example 2 except that Cu/CeO ₂ was used as a solid catalyst and the reaction temperature was 513 K (240° C.) or 533 K (260° C.). Table 1 shows the results.

[Experimental example 7]
(Production of solid catalyst)
Same as Experimental Example 1, except that 0.95 g of cerium oxide after firing and 0.25 g of Co(NO ₃ ) _{2.6H 2} O (manufactured by Wako Pure Chemical Industries, Ltd.), which is a cobalt (Co) precursor solution, were used. Similarly, a Co/CeO ₂ catalyst containing 5% by weight of cobalt was obtained.

(decomposition reaction)
Low-density polyethylene was decomposed in the same manner as in Experimental Example 2, except that Co/CeO ₂ was used as the solid catalyst and the reaction temperature was 513 K (240° C.) or 533 K (260° C.). Table 1 shows the results.

[Experimental example 8]
(Production of solid catalyst)
Same as Experimental Example 1, except that 0.95 g of cerium oxide after firing and 0.25 g of Ni(NO ₃ ) _{2.6H 2} O (manufactured by Wako Pure Chemical Industries, Ltd.), which is a nickel (Ni) precursor solution, were used. Similarly, a Ni/CeO ₂ catalyst containing 5% by weight of nickel was obtained.

(decomposition reaction)
Low-density polyethylene was decomposed in the same manner as in Experimental Example 2 except that Ni/CeO ₂ was used as the solid catalyst and the reaction temperature was 513 K (240° C.) or 533 K (260° C.). Table 1 shows the results.

In Table 1, Entry 1 is Experimental Example 1, Entries 2 and 3 are Experimental Example 2, Entries 4 and 5 are Experimental Example 3, Entries 6 and 7 are Experimental Example 4, Entries 8 and 9 are Experimental Example 5, Entries 10 and 11 are Experimental Example 6, Entries 12 and 13 are Experimental Example 7, and Entries 14 and 15 are Experimental Example 8.
Also, in Table 1, Temp. is the reaction temperature (K), Time is the reaction time (h), Yield is the yield (%-C), Conversion is the conversion rate (%-C), Carbon balance is the material balance (%-C), Number of cleavages is Cleavage number, Gas is C 1-4 gas generated by decomposition of low density polyethylene, Liquid fuels (fuel useful material) is C 5-21 oily substance generated by decomposition of low density polyethylene, Heavy oil (heavy oil) The crude oil) is an oil having 22 to 45 carbon atoms produced by decomposing low density polyethylene, and the lubricating oil (base lubricating oil) is an oil having 15 to 45 carbon atoms produced by decomposing low density polyethylene. For gases, useful fuels, and heavy oil, the number of carbon atoms was determined by boiling point. Also, the number of carbon atoms in the lubricating oil base was determined according to CAS: 72623-86-0.

Yield is expressed by the following formula (1), Conversion is expressed by the following formula (2), Carbon balance is expressed by the following formula (3), and Number of cleavages is expressed by the following formula. It is defined by formula (4).

The substrate is a plastic that decomposes using a solid catalyst, and in this experimental example it is low-density polyethylene.

From the results in Table 1, it was found that ruthenium exhibits high activity in the decomposition reaction of low-density polyethylene. In contrast, rhodium, platinum, palladium, copper, cobalt and nickel were found to be inactive in the decomposition reaction of low-density polyethylene.
In addition, iridium, which generally shows activity in hydrogenation decomposition of hydrocarbons, did not show activity at 513 K (240 ° C.), but slightly It was found that the reaction proceeded.

[Experimental example 9]
(decomposition reaction)
A low-density decomposed polyethylene. Table 2 shows the results.

[Experimental example 10]
(Production of solid catalyst)
Silicon oxide (SiO ₂ ) (manufactured by Fuji Silysia Chemical Co., Ltd.) was baked at 973 K (700° C.) for 1 hour.
0.95 g of silicon oxide (SiO ₂ ) after sintering and Ru(NO)(NO ₃ ) _3-x (OH) _x (ruthenium content: 1.5% by mass, manufactured by Aldrich) as a ruthenium precursor solution3. The mixture was dried at 383 K (110° C.) for 12 hours in an air atmosphere, and then heat-treated at 473 K (200° C.) for 1 hour in a nitrogen atmosphere to convert ruthenium to 5. A Ru/SiO ₂ catalyst containing wt % was obtained.

(decomposition reaction)
Low density polyethylene was degraded in the same manner as in Experimental Example 1, except that a Ru/ _SiO2 catalyst was used and the reaction time was 8 hours. Table 2 shows the results.

[Experimental example 11]
(Production of solid catalyst)
Magnesium oxide (MgO) (manufactured by Ube Industries, Ltd.) was fired at 973K (700°C) for 1 hour.
0.95 g of calcined magnesium oxide (MgO) and 3.33 g of Ru(NO)(NO ₃ ) _3-x (OH) _x (ruthenium content: 1.5% by mass, manufactured by Aldrich) as a ruthenium precursor solution The mixture is dried at 383 K (110 ° C.) for 12 hours in an air atmosphere, and then heat-treated at 473 K (200 ° C.) for 1 hour in a nitrogen atmosphere to obtain 5 mass of ruthenium. % of Ru/MgO catalyst was obtained.

(decomposition reaction)
Low-density polyethylene was decomposed in the same manner as in Experimental Example 1 except that a Ru/MgO catalyst was used and the reaction time was 4 hours. Table 2 shows the results.

[Experimental example 12]
(Production of solid catalyst)
Titanium oxide (TiO ₂ ) (manufactured by Nippon Aerosil Co., Ltd.) was sintered at 973 K (700° C.) for 1 hour.
0.95 g of calcined titanium oxide (TiO ₂ ) and Ru(NO)(NO ₃ ) _3-x (OH) _x (ruthenium content: 1.5% by mass, manufactured by Aldrich), which is a ruthenium precursor solution3. The mixture was dried at 383 K (110° C.) for 12 hours in an air atmosphere, and then heat-treated at 473 K (200° C.) for 1 hour in a nitrogen atmosphere to convert ruthenium to 5. A Ru/TiO ₂ catalyst containing wt % was obtained.

(decomposition reaction)
Low density polyethylene was degraded in the same manner as in Experimental Example 1, except that a Ru/TiO ₂ catalyst was used and the reaction time was 4 hours. Table 2 shows the results.

[Experimental example 13]
(Production of solid catalyst)
Zirconium oxide (ZrO ₂ ) (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) was fired at 973 K (700° C.) for 1 hour.
0.95 g of calcined zirconium oxide (ZrO ₂ ) and a ruthenium precursor solution Ru(NO)(NO ₃ ) _3-x (OH) _x (ruthenium content 1.5% by mass, manufactured by Aldrich)3. The mixture was dried at 383 K (110° C.) for 12 hours in an air atmosphere, and then heat-treated at 473 K (200° C.) for 1 hour in a nitrogen atmosphere to convert ruthenium to 5. A Ru/ZrO ₂ catalyst containing wt % was obtained.

(decomposition reaction)
Low density polyethylene was degraded in the same manner as in Experimental Example 1, except that a Ru/ZrO ₂ catalyst was used and the reaction time was 4 hours. Table 2 shows the results.

In Table 2, Entry 1 is Experimental Example 9, Entry 2 is Experimental Example 1, Entry 3 is Experimental Example 10, Entry 4 is Experimental Example 11, Entry 5 is Experimental Example 12, and Entry 6 is Experimental Example 13.
Moreover, in Table 2, Support is a solid catalyst, and the others are the same as in Table 1.

From the results in Table 2, the progress of hydrogenolysis of low-density polyethylene was confirmed regardless of the type of carrier.
Experimental Example 1 using cerium oxide as a carrier has a very low yield of C 1-4 gases, and a yield of C 5-21 oils useful as liquid fuels is lower than other Experimental Examples. It turns out there are many. Moreover, it was found that Experimental Example 1 yielded a higher yield of C15-45 oils useful as lubricating oil base materials than other Experimental Examples.
Since the number of cleavages is calculated based on the number of molecules, the number of cleavages increases when a low-molecular-weight product is obtained. Therefore, the number of times of cleavage increased in the experimental examples using carriers other than cerium oxide with high gas selectivity.
From the above results, it is considered that the Ru/ _CeO2 catalyst is the most suitable catalyst for cracking low density polyethylene.

[Experimental example 14]
(Production of solid catalyst)
Cerium oxide (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) was fired at 873 K (600° C.) for 3 hours.
0.95 g of cerium oxide after firing and 0.666 g of Ru(NO)(NO ₃ ) _3-x (OH) _x (ruthenium content: 1.5% by mass, manufactured by Aldrich), which is a ruthenium precursor solution, were mixed. Then, the mixture is dried at 383 K (110 ° C.) for 12 hours in an air atmosphere, and then heat-treated at 473 K (200 ° C.) for 1 hour in a nitrogen atmosphere to obtain Ru containing 1% by mass of ruthenium. /CeO ₂ catalyst was obtained.

(decomposition reaction)
Low density polyethylene was decomposed in the same manner as in Experimental Example 1, except that 500 mg of the resulting Ru/CeO ₂ catalyst was used. Table 3 shows the results.

[Experimental example 15]
(Production of solid catalyst)
Cerium oxide (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) was fired at 873 K (600° C.) for 3 hours.
0.95 g of cerium oxide after firing and 1.998 g of Ru(NO)(NO ₃ ) _3-x (OH) _x (ruthenium content 1.5% by mass, manufactured by Aldrich), which is a ruthenium precursor solution, were mixed. Then, the mixture is dried at 383 K (110° C.) for 12 hours in an air atmosphere, and then heat-treated at 473 K (200° C.) for 1 hour in a nitrogen atmosphere to obtain Ru containing 3% by mass of ruthenium. /CeO ₂ catalyst was obtained.

(decomposition reaction)
Low-density polyethylene was decomposed in the same manner as in Experimental Example 1, except that 167 mg of the resulting Ru/CeO ₂ catalyst was used. Table 3 shows the results.

[Experimental example 16]
(Production of solid catalyst)
Cerium oxide (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) was fired at 873 K (600° C.) for 3 hours.
0.95 g of cerium oxide after firing and 2.664 g of Ru(NO)(NO ₃ ) _3-x (OH) _x (ruthenium content 1.5% by mass, manufactured by Aldrich), which is a ruthenium precursor solution, were mixed. Then, the mixture is dried at 383 K (110 ° C.) for 12 hours in an air atmosphere, and then heat-treated at 473 K (200 ° C.) for 1 hour in a nitrogen atmosphere to obtain Ru containing 4% by mass of ruthenium. /CeO ₂ catalyst was obtained.

(decomposition reaction)
Low density polyethylene was decomposed in the same manner as in Experimental Example 1, except that 125 mg of the resulting Ru/CeO ₂ catalyst was used. Table 3 shows the results.

[Experimental example 17]
(Production of solid catalyst)
Cerium oxide (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) was fired at 873 K (600° C.) for 3 hours.
0.95 g of cerium oxide after firing and 2.997 g of Ru(NO)(NO ₃ ) _3-x (OH) _x (ruthenium content 1.5% by mass, manufactured by Aldrich), which is a ruthenium precursor solution, were mixed. Then, the mixture is dried at 383 K (110 ° C.) for 12 hours in an air atmosphere, and then heat-treated at 473 K (200 ° C.) for 1 hour in a nitrogen atmosphere to obtain 4.5% by mass of ruthenium. A Ru/CeO ₂ catalyst containing

(decomposition reaction)
Low density polyethylene was decomposed in the same manner as in Experimental Example 1, except that 111 mg of the resulting Ru/CeO ₂ catalyst was used. Table 3 shows the results.

[Experimental example 18]
(Production of solid catalyst)
Cerium oxide (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) was fired at 873 K (600° C.) for 3 hours.
0.95 g of cerium oxide after firing and 4.995 g of Ru(NO)(NO ₃ ) _3-x (OH) _x (ruthenium content 1.5% by mass, manufactured by Aldrich), which is a ruthenium precursor solution, were mixed. Then, the mixture is dried at 383 K (110 ° C.) for 12 hours in an air atmosphere, and then heat-treated at 473 K (200 ° C.) for 1 hour in a nitrogen atmosphere to reduce ruthenium to 7.5% by mass. A Ru/CeO ₂ catalyst containing

(decomposition reaction)
Low density polyethylene was decomposed in the same manner as in Experimental Example 1, except that 67 mg of the resulting Ru/CeO ₂ catalyst was used. Table 3 shows the results.

[Experimental example 19]
(Production of solid catalyst)
Cerium oxide (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) was fired at 873 K (600° C.) for 3 hours.
0.95 g of cerium oxide after firing and 6.66 g of Ru(NO)(NO ₃ ) _3-x (OH) _x (ruthenium content 1.5% by mass, manufactured by Aldrich), which is a ruthenium precursor solution, are mixed. Then, the mixture is dried at 383 K (110 ° C.) for 12 hours in an air atmosphere, and then heat-treated at 473 K (200 ° C.) for 1 hour in a nitrogen atmosphere to obtain Ru containing 10% by mass of ruthenium. /CeO ₂ catalyst was obtained.

(decomposition reaction)
Low density polyethylene was decomposed in the same manner as in Experimental Example 1, except that 50 mg of the resulting Ru/CeO ₂ catalyst was used. Table 3 shows the results.

In Table 3, Ru loading amount is the amount of ruthenium carried, Catalyst amount is the amount of solid catalyst used for decomposing low density polyethylene, and others are the same as in Table 1.
In Table 3, Experimental Example 14 when the Ru loading amount is 1 wt% (mass%), Experimental Example 15 when the Ru loading amount is 3 wt% (mass%), and Ru loading amount of 4 wt% (mass%) is Experimental Example 16, when Ru loading amount is 4.5 wt% (mass%), Experimental Example 17, when Ru loading amount is 5 wt% (mass%), Experimental Example 1, Ru loading amount is 7.5 wt% ( %), Experimental Example 18, and Experimental Example 19 when the Ru loading amount is 10 wt% (mass%).
In Experimental Examples 14 to 19, the amount of solid catalyst was increased or decreased in order to equalize the amount of metal during the reaction.

From the results in Table 3, a difference in catalytic activity was observed even though the amount of supported metal was uniformed by changing the amount of solid catalyst. It was found that when the supported amount of ruthenium is from 1 mass % to 5 mass %, the conversion rate increases with the supported amount, but the conversion rate decreases when the supported amount is further increased. On the other hand, when the supported amount of ruthenium exceeded 5% by mass, ruthenium agglomerated on the surface of CeO ₂ as a support, increasing the particle size of the solid catalyst, etc., and reducing the catalytic activity.
From the above results, it is considered that the case where the amount of ruthenium supported is 5% by mass is optimal from the viewpoint of hydrogenation resolution and catalyst structure.

[Experimental example 20]
Low-density polyethylene was decomposed in the same manner as in Experimental Example 1 except that the Ru/CeO ₂ catalyst produced in Experimental Example 1 was used, the reaction temperature was 513 K (240 ° C.), and the reaction time was 1 to 24 hours. , investigated the time course of the degradation reaction in low-density polyethylene. The results are shown in Table 4 and Figures 1 and 2.

The notation in Table 4 is the same as in Table 1. FIG. 1 shows the relationship between reaction time and conversion rate, the relationship between reaction time and yield of gas having 1 to 4 carbon atoms, the relationship between reaction time and yield of oily product having 5 to 21 carbon atoms, and the relationship between reaction time and carbon number. FIG. 2 is a diagram showing the relationship between the yield of oils having 22 to 45 carbon atoms and the relationship between the reaction time and the yield of oils having 15 to 45 carbon atoms. FIG. 2 is a diagram showing the results of analyzing the collected gas (vapor phase) and liquid phase at predetermined reaction times using a gas chromatograph/flame ionization detector (GC-FID).
From the results in Table 4 and FIG. 1, the conversion rate increased with the reaction time, and the conversion rate reached 100%-C at the reaction time of 8 hours. At this time, no residual solid was found.
In addition, from the results of FIG. 2, as the conversion rate increases, heavy oil, which is an oily substance with 22 to 45 carbon atoms that can be detected with a gas chromatograph/flame ionization detector (GC-FID) was found to increase.
The yield of C 5-21 oils (useful fuel) in a reaction time of 8 hours is 83.7%-C, and the yield of C 15-45 oils (lubricating oil base) is 36. .3%-C with a yield of C1-4 gases of less than 10%-C. When the reaction time is longer than 8 hours, the yield of C 1-4 gases and the number of cleavages increase, and C 5-21 oils (useful fuels) and C 15-45 oils. It was found that the yield of (lubricating oil base) decreased.

[Experimental example 21]
(Production of solid catalyst)
0.95 g of unfired H-USY (manufactured by Tosoh Corporation) and Pt(NH ₃ ) ₂ (NO ₂ ) ₂ (platinum content 4.564% by mass, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) which is a platinum precursor solution .22 g, the mixture is dried at 383 K (110° C.) for 12 hours in an air atmosphere, and then heat-treated at 473 K (200° C.) for 1 hour in a nitrogen atmosphere to convert platinum to A Pt/H-USY catalyst containing 1% by mass was obtained.

(decomposition reaction)
Low-density polyethylene was decomposed in the same manner as in Experimental Example 1, except that a Pt/H-USY catalyst was used, the reaction temperature was 533 K (260° C.), and the reaction time was 24 hours. Results are shown in Table 5 and FIG.

In Table 5, Catalyst is a solid catalyst, and others are the same as in Table 1. FIG. 3 shows the results of analyzing the gas (vapor phase) and liquid phase collected after the reaction in Experimental Examples 1 and 21 using a gas chromatograph/flame ionization detector (GC-FID). It is a diagram.
From the results in Table 5, in Experimental Example 21 using the Pt/H-USY catalyst, the oils having 22 to 45 carbon atoms (heavy oil) and the oils having 15 to 45 carbon atoms (lubricating oil base) were completely eliminated. I found that it doesn't generate
Further, from the results of FIG. 3, it was found that no C 15 to 45 oil (lubricating oil base) was produced at all.
Further, when comparing the residual solid after the reaction in Experimental Example 1 and the residual solid after the reaction in Experimental Example 21, although the residual solid was softened in Experimental Example 1, in Experimental Example 21, it was a hard solid similar to the substrate. was left. Therefore, in Experimental Example 21, by chain-cutting the C—C bonds from the ends of the low-density polyethylene molecules, oils with 22 to 45 carbon atoms (heavy oils) and oils with 15 to 45 carbon atoms (lubricating oil base) was not generated at all.

[Experimental example 22]
(decomposition reaction)
Low-density polyethylene was decomposed in the same manner as in Experimental Example 1, except that the reaction time was 8 hours. A nuclear magnetic resonance (NMR) spectrum ( ¹³ C) was measured for the sample after the reaction (conversion rate of 100%-C).
The results are shown in Tables 6 and 7 and FIG.

[Experimental example 23]
(decomposition reaction)
Low-density polyethylene was decomposed in the same manner as in Experimental Example 22, except that the reaction time was 42 hours. A nuclear magnetic resonance (NMR) spectrum ( ¹³ C) was measured for the sample after the reaction (conversion rate of 100%-C).
The results are shown in Tables 6 and 7 and FIG.

In Table 6, Catalyst is a solid catalyst, and others are the same as in Table 1. In Table 7, Amount of each products in carbon number 6 is the ratio of each product with 6 carbon atoms, and Selectivity to each products in carbon number 6 is the selectivity of each product with 6 carbon atoms. FIG. 4 is a diagram showing the results of ¹³ C NMR measurement for the sample of Experimental Example 22. FIG. FIG. 5 is a diagram showing the results of ¹³ C NMR measurement for the sample of Experimental Example 23. FIG.

From the results in Tables 6 and 7 and FIGS. 4 and 5, it was confirmed that in Experimental Example 22, almost a single linear product was obtained. On the other hand, in Experimental Example 23, it was confirmed that isomerization proceeded.

[Experimental example 24]
(decomposition reaction)
Low-density polyethylene (number average molecular weight Mn=7700) was decomposed in the same manner as in Experimental Example 1, except that the reaction time was 12 hours. Table 8 shows the results.

[Experimental example 25]
(decomposition reaction)
High-density polyethylene was decomposed in the same manner as in Experimental Example 1, except that the reaction time was 10 hours. Table 8 shows the results.

In Table 8, the substrate is the plastic to be decomposed, and the others are the same as in Table 1. Table 8 also shows the results of Experimental Example 22.
From the results in Table 8, it was confirmed that equivalent results can be obtained with low-density polyethylene by changing the reaction time (longer reaction time if the molecular weight is large) regardless of the molecular weight. rice field. In high-density polyethylene, the yield of gas was high and the yield of oils with 15 to 45 carbon atoms (base lubricating oil) was low. The yield of (fuel useful material) was over 80%-C.

[Experimental example 26]
(reuse experiment)
To confirm the durability of the Ru/ _CeO2 catalyst, a reuse experiment of the Ru/ _CeO2 catalyst was performed.
Low-density polyethylene was decomposed in the same manner as in Experimental Example 1, except that the reaction time was 8 hours.
After completion of the reaction, the recovered gas (vapor phase) and liquid phase were analyzed in the same manner as in Experimental Example 1.
Further, the solid catalyst after completion of the reaction was recovered by centrifugation, washed with hexane three times, and then dried for 12 hours.
If the amount of solid catalyst after drying is less than the predetermined amount of 100 mg, add a new Ru/ _CeO2 catalyst to make up for the shortfall to make the amount of solid catalyst 100 mg, and then crack the low-density polyethylene again. did
The above decomposition and washing were repeated 5 times. Table 9 shows the results.

In Table 9, Usage Time is the number of decomposition experiments, and the others are the same as in Table 1.
From the results in Table 9, although there are some errors, the solid catalyst did not deactivate and showed constant results. Therefore, it was confirmed that the Ru/CeO ₂ catalyst is a reusable catalyst and highly durable.

In addition, before and after the decomposition reaction, X-ray diffraction (XRD) measurement of the Ru/CeO ₂ catalyst was performed in order to confirm whether the structure of the Ru/CeO ₂ catalyst had changed. The results are shown in FIG.
The samples used for the measurement were CeO ₂ as a carrier and Ru/CeO ₂ catalyst that had undergone a reduction treatment (heat treatment at 513 K (240° C.) for 1 hour) assuming a Ru/CeO ₂ catalyst before reaction. , used a Ru/CeO ₂ catalyst that had undergone a recycling treatment as described above.
Since the Ru/CeO ₂ catalyst is a catalyst in which ruthenium having a particle size of 1.5 nm or less is highly dispersedly supported, it is difficult to observe a peak in X-ray diffraction (XRD). Since the three diffraction patterns shown in FIG. 6 are similar and no ruthenium peak is observed, it is considered that ruthenium is not aggregated even after the decomposition reaction and is supported in a highly dispersed manner.

[Experimental example 27]
(Production of solid catalyst)
Cerium oxide (CeO ₂ ) (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) is fired for 3 hours at 873K (600°C), 973K (700°C), 1073K (800°C) or 1273K (1000°C) in an air atmosphere. bottom. Moreover, the specific surface area of the obtained cerium oxide was determined by the BET method. A fully automatic specific surface area measuring device (trade name: Gemini VII2360, manufactured by Shimadzu Corporation) was used to measure the specific surface area of cerium oxide.
0.95 g of cerium oxide after firing and 3.33 g of Ru(NO)(NO ₃ ) _3-x (OH) _x (ruthenium content 1.5% by mass, manufactured by Aldrich), which is a ruthenium precursor solution, were mixed. The mixture was dried at 110° C. for 12 hours in an air atmosphere and then heat-treated at 300° C. for 1 hour in a nitrogen atmosphere to obtain a Ru/CeO ₂ catalyst containing 5% by mass of ruthenium. rice field.

(decomposition reaction)
Low-density polyethylene was decomposed in the same manner as in Experimental Example 1 using the Ru/CeO ₂ catalyst obtained. Table 10 shows the results.

In Table 10, Entry 1 has a cerium oxide firing temperature of 873 K (600 ° C.) and a nitrogen atmosphere when supporting ruthenium on cerium oxide. The atmosphere for supporting ruthenium on cerium is an air atmosphere. Entry 3 has a firing temperature of 973 K (700° C.) for cerium oxide, and the atmosphere for supporting ruthenium on cerium oxide is a nitrogen atmosphere. The sintering temperature is 1073K (800°C), and the atmosphere for supporting ruthenium on cerium oxide is a nitrogen atmosphere. A nitrogen atmosphere.

The Ru/ _CeO catalyst in Entry 2 has a particle size of about 7 nm, and the Ru/ _CeO catalyst in Entry 1 has a ruthenium particle size of 1.5 nm. presumably decreased. Since cerium oxide is the only support capable of supporting ruthenium in a highly dispersed manner, it is believed that the particle size of ruthenium has a great effect on the decomposition of low-density polyethylene.
The Ru/CeO ₂ catalyst of Entry 3 had a cerium oxide specific surface area of 58.7 m ² /g. The Ru/CeO ₂ catalyst of Entry 4 had a cerium oxide specific surface area of 43.4 m ² /g. The Ru/CeO ₂ catalyst of Entry 5 had a cerium oxide specific surface area of 15.4 m ² /g. Thus, as the firing temperature of cerium oxide increases, the specific surface area decreases. It was confirmed that the conversion rate increased by decreasing the specific surface area of cerium oxide. Therefore, it was suggested that by adjusting the specific surface area of cerium oxide, a more highly active solid catalyst could be obtained.

[Experimental example 28]
(Production of solid catalyst)
Cerium oxide (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) is heated at 773 K (500° C.), 873 K (600° C.), 1073 K (800° C.), 1273 K (1000° C.) or 1373 K (1100° C.) in an air atmosphere. Baked for hours. Moreover, the specific surface area of the obtained cerium oxide was determined by the BET method. A fully automatic specific surface area measuring device (trade name: Gemini VII2360, manufactured by Shimadzu Corporation) was used to measure the specific surface area of cerium oxide.
0.95 g of cerium oxide after firing and 3.33 g of Ru(NO)(NO ₃ ) _3-x (OH) _x (ruthenium content 1.5% by mass, manufactured by Aldrich), which is a ruthenium precursor solution, were mixed. The mixture was dried at 110° C. for 12 hours in an air atmosphere and then heat-treated at 300° C. for 1 hour in a nitrogen atmosphere to obtain a Ru/CeO ₂ catalyst containing 5% by mass of ruthenium. rice field.

X-ray diffraction (XRD) measurements and H ₂ adsorption of the resulting Ru/CeO ₂ catalyst were performed. 100 mg of catalyst was reduced at 573 K (300° C.) for 1 hour followed by H ₂ adsorption at room temperature. Since adsorption as a hydrogen (H) atom is assumed, the dispersity is defined by the following formula (5).
Dispersity = 2 x (amount of hydrogen adsorption)/(amount of Ru in catalyst) (5)
The results are shown in Table 11 and Figures 7 and 8.

In Table 11, Calcination Temperature is the calcination temperature of cerium oxide, BET Surface Area of CeO ₂ is the BET specific surface area of cerium oxide, Ru amount in catalyst is the amount of ruthenium supported in the Ru/CeO ₂ catalyst, and Ru particle size by XRD is X. The particle size of ruthenium obtained by line diffraction measurement, H ₂ chemisorption is the amount of hydrogen chemisorption in the Ru/CeO ₂ catalyst, Dispersion is the degree of dispersion defined by the above formula (5), Ru particle size by H ₂ chemisorption is the particle size of ruthenium obtained by _H2 adsorption.
From the results in Table 11, it was found that when the firing temperature of cerium oxide is 1073 K (800° C.) or higher, the particle size of ruthenium increases and the chemical adsorption amount of hydrogen decreases. A decrease in the amount of hydrogen chemisorption implies a decrease in the surface amount of Ru in the Ru/ _CeO2 catalyst.

FIG. 7 shows the results of X-ray diffraction (XRD) measurements of the Ru/CeO ₂ catalyst. FIG. 8 is an enlarged view of a part of FIG.
The results in FIGS. 7 and 8 provide information about the state of dispersion of Ru and information about the particle size of the Ru/CeO ₂ catalyst particles.

[Experimental example 29]
(Production of solid catalyst)
Cerium oxide (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) was fired at 873 K (600° C.), 1073 K (800° C.) or 1273 K (1000° C.) for 3 hours in an air atmosphere. Moreover, the specific surface area of the obtained cerium oxide was determined by the BET method. A fully automatic specific surface area measuring device (trade name: Gemini VII2360, manufactured by Shimadzu Corporation) was used to measure the specific surface area of cerium oxide.
Thereafter, in the same manner as in Experimental Example 1, a Ru/CeO ₂ catalyst containing 5% by mass of ruthenium was obtained.

(decomposition reaction)
Low-density polyethylene was decomposed in the same manner as in Experimental Example 1 using the Ru/CeO ₂ catalyst obtained.
Ru/CeO ₂ catalyst using cerium oxide calcined at 873 K (600 ° C.), (Entry 1) reaction temperature of 513 K (240 ° C.), reaction time of 8 hours, (Entry 2) reaction temperature of 493 K (220 ° C.), The reaction time was 48 hours, (Entry 3) the reaction temperature was 473 K (200°C), and the reaction time was 144 hours.
Ru/CeO ₂ catalyst using cerium oxide calcined at 1073 K (800 ° C.), (Entry 4) reaction temperature of 513 K (240 ° C.), reaction time of 5 hours, (Entry 5) reaction temperature of 493 K (220 ° C.), The reaction time was 30 hours, (Entry 6) the reaction temperature was 473 K (200°C), and the reaction time was 90 hours.
Ru/CeO ₂ catalyst using cerium oxide calcined at 1273 K (1000 ° C.), (Entry 7) reaction temperature of 513 K (240 ° C.), reaction time of 4 hours, (Entry 8) reaction temperature of 493 K (220 ° C.), The reaction time was 24 hours, (Entry 9) the reaction temperature was 473 K (200°C), and the reaction time was 72 hours.
Table 12 shows the results.

In Table 12, Calc. Temp. is the firing temperature of cerium oxide, BET Surf. Area is the BET specific surface area of cerium oxide, Conv. is the conversion rate (%-C), C.I. B. is material balance (%-C), Activity is catalytic activity, and others are the same as in Table 1.

From the results in Table 12, Entry2 and Entry3 yielded results equivalent to Entry1.
In addition, Entry 5 and Entry 6 have a slightly higher yield of C 1-4 gas than Entry 4, and a lower yield of C 22-45 oil (heavy oil). It was found that the yield of oil (fuel useful material) was improved.
In addition, Entry 8 and Entry 9 have a slightly higher yield of C 1-4 gas than Entry 7, and a lower yield of C 22-45 oil (heavy oil), but C 5-21 It was found that the yield of oil (fuel useful material) was improved.

[Experimental example 30]
(decomposition reaction)
100 mg or 200 mg of the Ru/CeO ₂ catalyst similar to Experimental Example 1, 3.4 g of polypropylene (number average molecular weight Mn=5000), and a glass stirrer tip were charged into the reactor.
Thereafter, polypropylene was decomposed in the same manner as in Experimental Example 1 except that the reaction time was set to 72 hours, 75 hours, 96 hours or 120 hours. The results are shown in Table 13.

In Table 13, Entry 1 has a Ru/CeO ₂ catalyst amount of 100 mg and a reaction time of 75 hours, Entry 2 has a Ru/CeO ₂ catalyst amount of 100 mg and a reaction time of 96 hours, and Entry 3 has a Ru/CeO ₂ catalyst amount of 100 mg, reaction time is 120 hours, entry 4 is Ru/ _CeO2 catalyst amount of 200 mg, reaction time is 72 hours, entry 5 is Ru/ _CeO2 catalyst amount of 200 mg, reaction time is 96 hours, others are Table 12 is similar to

From the results in Table 13, in Entry 4, the yield of C5-C21 oily substance (useful fuel substance) was the highest at the reaction time of 72 hours. In Entry 4, the yield of C 5-21 oils (fuel useful substances) is 72.2%-C, while the yield of C 1-4 gases is 21.0%-C. , it seems preferable to stop the reaction shortly before 100.0%-C conversion.
Also, the activity of the catalyst was 0.004 μmol/g/h in Entry 4. This value was obtained under conditions where the yield was maximized in the decomposition of low-density polyethylene (the amount of Ru/ _CeO2 catalyst was 100 mg, the amount of low-density polyethylene was 3.4 g, the hydrogen pressure was 6 MPa, and the reaction temperature was 513 K (240°C). , reaction time of 8 hours), the value was 1/10 of the activity of the catalyst (0.050 μmol/g/h).

[Experimental example 31]
(Production of solid catalyst)
Cerium oxide (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) was calcined at 873 K (600° C.) for 5 hours or at 1073 K (800° C.) for 4 hours in an air atmosphere.
Moreover, the specific surface area of the obtained cerium oxide was determined by the BET method. A fully automatic specific surface area measuring device (trade name: Gemini VII2360, manufactured by Shimadzu Corporation) was used to measure the specific surface area of cerium oxide.
A Ru/CeO ₂ catalyst containing 5% by mass of ruthenium was obtained in the same manner as in Experimental Example 1 using two types of cerium oxide with different calcination temperatures.

(decomposition reaction)
Low-density polyethylene was decomposed in the same manner as in Experimental Example 1 using the Ru/CeO ₂ catalyst obtained. The results are shown in Table 14.

[Experimental example 32]
(Production of solid catalyst)
Zirconium oxide (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) was fired at 873 K (600° C.) for 4 hours.
Also, the specific surface area of the resulting zirconium oxide was determined by the BET method. A fully automatic specific surface area measuring device (trade name: Gemini VII2360, manufactured by Shimadzu Corporation) was used to measure the specific surface area of zirconium oxide.
Thereafter, a Ru/ZrO ₂ catalyst containing 5% by mass of ruthenium was obtained in the same manner as in Experimental Example 1 using calcined zirconium oxide and uncalcined zirconium oxide.

(decomposition reaction)
Low-density polyethylene was decomposed in the same manner as in Experimental Example 1 using the Ru/ZrO ₂ catalyst obtained. The results are shown in Table 14.

In Table 14, Entry 1 uses a Ru/CeO ₂ catalyst containing cerium oxide calcined at 873 K (600°C), and Entry 2 uses a Ru/CeO ₂ catalyst containing cerium oxide calcined at 1073 K (800°C). _{The Ru/ZrO 2 catalyst} containing zirconium oxide calcined at 873 K (600° C.) was Entry 4. In Table 14, Calculation Temperature of support is the calcination temperature of cerium oxide and zirconium oxide, BET surface area is the BET specific surface area of cerium oxide and zirconium oxide, and the others are the same as in Table 1.

From the results of Table 14, in Entry 1 to 3, the yield of C 5 to 21 oil (fuel useful substance) is high, and in Entry 4, the yield of C 5 to 21 oil (fuel useful substance) is high. found to be low. It was also found that in Entry 1 to 3, the yield of gas with 1 to 4 carbon atoms was low, and in Entry 4, the yield of gas with 1 to 4 carbon atoms was high.

Claims (4)

A solid catalyst used for the decomposition reaction of polyolefin,
A carrier made of a metal oxide and ruthenium supported on the carrier,
a specific surface area of 10 m ² /g or more and 1000 m ² /g or less ;
The solid catalyst, wherein the metal oxide is at least one selected from the group consisting of cerium oxide, silicon oxide, magnesium oxide, titanium oxide and zirconium oxide. 2. The solid catalyst according to claim 1, wherein the supported amount of ruthenium is 1% by mass or more and 30% by mass or less. A method for producing a solid catalyst used in a polyolefin decomposition reaction, comprising:
a step of firing the metal oxide at 600° C. or higher and 1500° C. or lower in an air atmosphere;
and heat-treating the mixture of the fired metal oxide and ruthenium at 200° C. or more and 1000° C. or less in a nitrogen atmosphere ;
The method for producing a solid catalyst, wherein the metal oxide is at least one selected from the group consisting of cerium oxide, silicon oxide, magnesium oxide, titanium oxide and zirconium oxide. 3. A method for producing an oily substance, comprising the steps of bringing the solid catalyst according to claim 1 or 2 into contact with a polyolefin having a melting point of 250° C. or lower, and heat-treating the polyolefin at 100° C. or higher under hydrogen.

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