Solid catalyst for plastic decomposition and method for producing liquid oil

Abstract

To provide a solid catalyst which has excellent plastic decomposition activity even when a catalyst poison coexists.SOLUTION: Provided is a solid catalyst for plastic decomposition comprising a support and ruthenium supported on the support, the support being a composite metal oxide.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a solid catalyst for decomposing plastics and a method for producing a liquid oil. [Background technology]

[0002] Development of chemical recycling is underway, in which polyolefin plastics, such as polyethylene, are decomposed and the resulting liquid oil is reused as fuel or a raw material for chemicals. Known methods for chemical recycling of plastics include thermal decomposition without a catalyst and thermal decomposition using a catalytic cracking catalyst (Patent Documents 1 and 2), but these methods require the decomposition reaction to be carried out at high temperatures of 400°C or higher, which makes them inefficient in terms of energy efficiency. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-221681 [Patent Document 2] Special Publication No. 2011-508808 [Patent Document 3] Japanese Patent Publication No. 2020-185513 Summary of the Invention [Problem to be solved by the invention]

[0004] Furthermore, the hydrocracking of polyolefins using a solid catalyst with a specific specific surface area containing cerium oxide and ruthenium supported on the cerium oxide has been reported (Patent Document 3). According to this method, plastics are decomposed at a reaction temperature of about 250°C. However, the solid catalyst described in Patent Document 3 has the problem that its catalytic activity becomes insufficient in the presence of catalyst poisons such as sulfur compounds and phosphorus compounds. An object of the present invention is to provide a solid catalyst that has excellent plastic decomposition activity even in the presence of a catalyst poison. [Means for solving the problem]

[0005] As a result of extensive research, the present inventors have found that a solid catalyst comprising a carrier and ruthenium supported on the carrier, wherein the carrier is a composite metal oxide, has excellent plastic decomposition activity even in the coexistence of a catalyst poison, and have completed the present invention.

[0006] That is, the present invention provides the following: <1> ~ <8> This provides: <1> A solid catalyst for plastic decomposition (hereinafter also referred to as the solid catalyst of the present invention or the solid catalyst for plastic decomposition of the present invention) comprising a support and ruthenium supported on the support, wherein the support is a composite metal oxide. <2> The composite metal oxide is a composite metal oxide containing zirconium dioxide. <1> The solid catalyst according to claim 1. <3> The composite metal oxide is a composite metal oxide containing zirconium dioxide and at least one selected from oxides of Group 13 metals and oxides of lanthanoids. <1> The solid catalyst according to claim 1. <4> The composite metal oxide is a composite metal oxide containing zirconium dioxide and at least one selected from aluminum oxide, lanthanum (III) oxide, and cerium (IV) oxide. <1> The solid catalyst according to claim 1.

[0007] <5> <1> ~ <4> A method for producing a liquid oil, comprising a hydrocracking step of heat-treating a plastic-containing material in the presence of the solid catalyst according to any one of the above items under a hydrogen atmosphere (hereinafter also referred to as the liquid oil production method of the present invention). <6> The temperature of the heat treatment is in the range of 100°C or higher and 350°C or lower. <5> The manufacturing method described in <7> The plastic-containing material further contains at least one selected from sulfur, sulfur compounds, phosphorus, and phosphorus compounds. <5> or <6> The manufacturing method described in <8> The plastic is a polyolefin. <5> ~ <7> 1. The manufacturing method according to any one of the preceding claims. [Effects of the Invention]

[0008] The solid catalyst of the present invention has excellent plastic decomposition activity even in the presence of a catalyst poison. Therefore, according to the method for producing liquid oil of the present invention, even when materials containing catalyst poisons as well as plastics are used as raw materials, liquid oil can be efficiently obtained from plastics. DETAILED DESCRIPTION OF THE INVENTION

[0009] <Solid catalyst> The solid catalyst for decomposing plastics of the present invention comprises a support and ruthenium supported on the support, and is characterized in that the support is a composite metal oxide. "Solid catalyst for decomposing plastics" means a solid catalyst used for decomposing plastics.

[0010] "Composite metal oxide" refers to a combination of two or more metal oxides. As the metal oxide, oxides of metals of Groups 2 to 13 are preferred, and oxides of Group 2 metals such as magnesium oxide (MgO) and calcium oxide (CaO); oxides of lanthanoids such as lanthanum (III) oxide (La2O3) and cerium (IV) oxide (CeO2); oxides of Group 4 metals such as zirconium dioxide (ZrO2) and titanium (IV) oxide (TiO2); and oxides of Group 13 metals such as aluminum oxide (Al2O3) and gallium oxide (Ga2O3) are more preferred. From the viewpoints of reaction efficiency, catalyst toxicity resistance, and the like, the composite metal oxide is preferably a composite metal oxide containing an oxide of a Group 4 metal, more preferably a composite metal oxide containing zirconium dioxide, even more preferably a composite metal oxide containing zirconium dioxide and at least one selected from oxides of Group 13 metals and oxides of lanthanoids, and even more preferably a composite metal oxide containing zirconium dioxide and at least one selected from aluminum oxide, lanthanum (III) oxide, and cerium (IV) oxide. When the plastic content (raw plastic) contains sulfur and / or sulfur compounds as a catalyst poison, from the viewpoints of reaction efficiency, catalyst toxicity resistance, etc., a composite metal oxide containing zirconium dioxide and at least one selected from aluminum oxide and cerium (IV) oxide is preferred, and a composite metal oxide containing zirconium dioxide and aluminum oxide is more preferred. When the plastic content (raw plastic) contains phosphorus and / or a phosphorus compound as a catalyst poison, a composite metal oxide containing zirconium dioxide and lanthanum (III) oxide is preferred from the standpoints of reaction efficiency, catalyst toxicity resistance, etc.

[0011] From the viewpoints of reaction efficiency, catalyst toxicity resistance, reduction in gas component generation, etc., the content of the composite metal oxide is preferably 70% by mass or more and 99% by mass or less, more preferably 80% by mass or more and 98% by mass or less, and particularly preferably 90% by mass or more and 97% by mass or less, relative to 100% by mass of the total mass of the solid catalyst. The content of the composite metal oxide can be calculated, for example, from the theoretical charged amount.

[0012] When the solid catalyst of the present invention contains an oxide of a Group 4 metal (preferably zirconium dioxide (ZrO)) as a composite metal oxide, the content of the oxide of the Group 4 metal is preferably from 1 to 95 mass%, more preferably from 5 to 90 mass%, and particularly preferably from 9 to 87 mass%, relative to the total mass of the solid catalyst (100 mass%), from the viewpoints of reaction efficiency, catalyst toxicity resistance, reduction in gas component generation, etc.

[0013] When the solid catalyst of the present invention contains at least one selected from oxides of Group 13 metals and oxides of lanthanoids (preferably at least one selected from aluminum oxide, lanthanum (III) oxide, and cerium (IV) oxide) as a composite metal oxide, the content of the at least one selected from oxides of Group 13 metals and oxides of lanthanoids is preferably from 1 to 94 mass%, more preferably from 4 to 90 mass%, and particularly preferably from 8 to 86 mass%, relative to the total mass of the solid catalyst (100 mass%), from the viewpoints of reaction efficiency, catalyst toxicity resistance, reduction in gas component generation, and the like.

[0014] When the solid catalyst of the present invention contains, as the composite metal oxide, an oxide of a Group 4 metal (preferably zirconium dioxide (ZrO)) and at least one or more oxides selected from oxides of Group 13 metals and oxides of lanthanoids (preferably at least one or more selected from aluminum oxide, lanthanum (III) oxide, and cerium (IV) oxide), the mass ratio of the content of the at least one or more oxides selected from oxides of a Group 13 metal and oxides of a lanthanoid to the oxide of the Group 4 metal [(oxide of a Group 4 metal) / (at least one or more oxides selected from oxides of a Group 13 metal and oxides of a lanthanoid)] is preferably from 0.01 to 20, more preferably from 0.05 to 17.5, even more preferably from 0.075 to 15, and particularly preferably from 0.1 to 11, from the viewpoints of reaction efficiency, catalyst toxicity resistance, reduction in generation of gas components, and the like.

[0015] The amount of ruthenium supported is preferably 1% by mass or more and 30% by mass or less, more preferably 2% by mass or more and 20% by mass or less, and particularly preferably 3% by mass or more and 10% by mass or less, relative to 100% by mass of the total mass of the solid catalyst, from the viewpoints of reaction efficiency, catalyst toxicity resistance, reduction in gas component generation, ruthenium particle size, and the like. The amount of ruthenium supported on the solid catalyst can be calculated, for example, from the theoretical charged amount.

[0016] The mass ratio of ruthenium to the composite metal oxide [(ruthenium) / (composite metal oxide)] is preferably 0.005 or more and 1 or less, more preferably 0.0075 or more and 0.5 or less, even more preferably 0.01 or more and 0.3 or less, and particularly preferably 0.03 or more and 0.1 or less, from the viewpoints of reaction efficiency, catalyst toxicity resistance, reduction in gas component generation, and the like.

[0017] The specific surface area of ​​the solid catalyst of the present invention is 10 m from the viewpoints of reaction efficiency, catalyst toxicity resistance, supported ruthenium particle size, etc. 2 / g or more 1000m 2 / g or less is preferable, and 10m 2 / g or more 500m 2 / g or less is more preferable, and 20m 2 / g or more 300m 2 / g or less is more preferable. The specific surface area of ​​the solid catalyst can be determined by the BET method, for example, using a fully automatic specific surface area measuring device (trade name: Gemini VII2360, manufactured by Shimadzu Corporation).

[0018] The solid catalyst of the present invention has excellent plastic decomposition activity even in the presence of catalyst poisons. It is useful for producing liquid oils, particularly liquid oils having 5 to 21 carbon atoms. It also exhibits plastic decomposition activity even under low-temperature conditions, and the catalyst can be easily recovered and regenerated after the reaction is complete. The solid catalyst can be easily recovered by filtration, and can be reused for plastic decomposition by washing with an organic solvent.

[0019] The solid catalyst of the present invention can be produced by appropriately combining known catalyst production methods (for example, JP-A-2020-185513, U.S. Patent No. 4,556,477, etc.), except that ruthenium is supported on a composite metal oxide carrier. The method for producing the solid catalyst may include, for example, a method including a supporting step of supporting ruthenium on a composite metal oxide and a heat treatment step of heat-treating the product obtained in the supporting step. Furthermore, a calcination step of calcining the composite metal oxide may be carried out prior to the supporting step.

[0020] The composite metal oxide to be used may be a commercially available product or one prepared according to a conventional method. The firing temperature in the firing step is preferably in the range of 500°C to 1500°C, more preferably in the range of 600°C to 1000°C. The firing step is preferably carried out in an air atmosphere or a nitrogen atmosphere. The firing time in the firing step is preferably 0.1 to 1440 hours, more preferably 0.5 to 720 hours. The means for firing the composite metal oxide is not particularly limited, but examples include a method of firing in a firing furnace and a method of firing in a tubular flow device.

[0021] The supporting step may involve, for example, mixing a composite metal oxide with ruthenium. The method for this mixing is not particularly limited, but for example, a composite metal oxide that has been calcined as necessary may be mixed with a ruthenium precursor solution, Ru(NO)(NO). 3-x (OH) x The ruthenium content is preferably 0.1 to 15 mass %, more preferably 0.3 to 10 mass %, and particularly preferably 0.5 to 5 mass %, relative to the total mass of the ruthenium precursor solution (100 mass %). The method for heat-treating the product obtained in the supporting step includes heating and drying in an air atmosphere or a nitrogen atmosphere, followed by heat-treating in a hydrogen atmosphere or a nitrogen atmosphere. The heating temperature in this heat-treatment step is preferably in the range of 200°C to 1000°C, more preferably in the range of 300°C to 800°C, from the viewpoints of reaction efficiency, catalyst toxicity resistance, ruthenium particle size, etc. The heating time in the heat-treatment step is preferably 0.25 hours or more, more preferably 0.5 hours or more. The means for heat-treating the product obtained in the supporting step is not particularly limited, but examples thereof include a method of heat-treating in a calcination furnace and a method of heat-treating in a tubular flow device.

[0022] <Method for producing liquid oil> The method for producing a liquid oil of the present invention comprises a hydrocracking step in which a plastic-containing material is heat-treated in the presence of the solid catalyst of the present invention under a hydrogen atmosphere. The plastic-containing material may be any material that contains plastic. The plastic content is preferably 50% by mass or more and 100% by mass or less, more preferably 75% by mass or more and 99.99% by mass or less, and particularly preferably 90% by mass or more and 99.99% by mass or less, based on the total mass of the plastic-containing material (100% by mass). The melting point of the plastic is preferably 250°C or lower, more preferably in the range of 100°C or higher and 180°C or lower. Examples of plastics include polyolefins such as polyethylene (PE) and polypropylene (PP); polyvinyl chloride (PVC); polyethylene terephthalate (PET); polycarbonate (PC); polyamide (PA); and epoxy resins. These plastics account for the majority of waste plastics. Among these plastics, hydrocarbon-based plastics are preferred, polyolefins are more preferred, and polyethylene is particularly preferred. Examples of polyethylene include low-density polyethylene, high-density polyethylene, and medium-density polyethylene.

[0023] The plastic-containing material preferably further contains a catalyst poison in addition to the plastic. According to the present invention, even if the plastic-containing material contains a catalyst poison in addition to the plastic, liquid oil can be efficiently obtained from the plastic. The catalyst poison is preferably at least one selected from sulfur (element), sulfur compounds, phosphorus (element), and phosphorus compounds. Examples of sulfur compounds include hydrogen sulfide; sulfur dioxide; sulfur trioxide; thiols such as methanethiol, ethanethiol, propanethiol, thiophenol, and 2-mercaptobenzimidazole; sulfides such as methyl sulfide, ethyl sulfide, and propyl sulfide; thiophene; dialkyl-3,3'-thiodipropionates such as dilauryl-3,3'-thiodipropionate, ditridecyl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, and distearyl-3,3'-thiodipropionate; and pentaerythritol tetrakis[3-laurylthiopropionate]. Examples of phosphorus compounds include phosphinic acid; phosphine; inorganic phosphine oxides such as phosphoric acid, phosphorous acid, and phosphine oxide (HOP); phosphite esters such as trimethyl phosphite, triethyl phosphite, tributyl phosphite, tridecyl phosphite, trilauryl phosphite, tristearyl phosphite, triphenyl phosphite, tricresyl phosphite, and trisnonylphenyl phosphite; phosphate esters such as trimethyl phosphate, triethyl phosphate, and triphenyl phosphate; trialkyl phosphines such as trimethyl phosphine and triethyl phosphine; and triaryl phosphines such as triphenyl phosphine.

[0024] The content of the catalyst poison is preferably 0.01 ppm or more and 500,000 ppm or less, and more preferably 0.1 ppm or more and 200,000 ppm or less, based on the total mass of the plastic content. When the plastic-containing material contains at least one selected from sulfur, sulfur compounds, phosphorus, and phosphorus compounds as a catalyst poison, the total content of at least one selected from sulfur, sulfur compounds, phosphorus, and phosphorus compounds is preferably 0.001 ppm or more and 50,000 ppm or less, more preferably 0.01 ppm or more and 20,000 ppm or less, in terms of sulfur atoms or phosphorus atoms, relative to the total mass of the plastic-containing material.

[0025] The plastic content may include plasticizers, colorants, etc. in addition to plastics and catalyst poisons. Specific examples of such plastic-containing materials include waste plastics (for example, waste plastics derived from discarded home appliances, discarded containers, discarded packaging, etc.).

[0026] The amount of the solid catalyst of the present invention used in the hydrocracking step is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 6 parts by mass, per 100 parts by mass of plastic, from the viewpoints of reaction efficiency, catalyst toxicity resistance, etc. When the plastic-containing material contains at least one or more catalyst poisons selected from sulfur, sulfur compounds, phosphorus, and phosphorus compounds, the amount of the solid catalyst of the present invention used (in ruthenium equivalent) is, from the viewpoints of reaction efficiency, catalyst toxicity resistance, etc., preferably 20 moles or more and 10,000 moles or less, more preferably 50 moles or more and 1,000 moles or less, even more preferably 100 moles or more and 750 moles or less, and particularly preferably 150 moles or more and 500 moles or less, per 100 moles of the total sulfur atom or phosphorus atom equivalent of at least one or more catalyst poisons selected from sulfur, sulfur compounds, phosphorus, and phosphorus compounds. From the viewpoints of reaction efficiency, energy efficiency, prevention of sintering of ruthenium particles, etc., the temperature of the heat treatment in the hydrocracking step is preferably in the range of 100° C. or higher and 350° C. or lower, more preferably in the range of 120° C. or higher and 325° C. or lower, even more preferably in the range of 140° C. or higher and 300° C. or lower, and particularly preferably in the range of 160° C. or higher and 250° C. According to the present invention, liquid oil can be produced from plastic even at such low temperatures, and in this case, energy efficiency is particularly excellent. The hydrocracking step is preferably a heat treatment under hydrogen pressure conditions. From the viewpoint of reaction efficiency, the hydrogen pressure in the hydrocracking step is preferably normal pressure to 30 MPa, more preferably 1 to 10 MPa, and particularly preferably 5 to 6 MPa. The reaction time for the hydrocracking step is preferably 0.1 hours or more and 100 hours or less, more preferably 1 hour or more and 72 hours or less. Furthermore, according to the liquid oil production method of the present invention, even when a material containing a catalyst poison is used as raw material together with the plastic, liquid oil can be efficiently obtained from the plastic. The present invention is particularly suitable for producing liquid oil having 5 to 21 carbon atoms. [Example]

[0027] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0028] (Example 1 Solid Catalyst) Ru / La2O3-ZrO2 was prepared by the incipient-wetness method. (1) 0.9542 g of La2O3-ZrO2 (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd. (mass ratio [(ZrO2) / (La2O3)] = 91 / 9)) was added to a 100 mL beaker. 3.3251 g of Ru(NO)(NO3)3 solution (manufactured by Sigma-Aldrich, Ru: 1.5%; hereinafter, also referred to as Ru precursor solution) was added to a 5 mL sample bottle. (2) Next, while the La2O3-ZrO2 was heated to a temperature in the range of 353 to 363 K using a hot stirrer, the Ru precursor solution was added little by little and mixed thoroughly based on the incipient-wetness method to allow the Ru precursor solution to be supported. (3) After removing the moisture on a hot stirrer, the mixture was dried overnight in an oven at 383 K and then calcined at 573 K for 1 hour (heating rate: 20 K / min) in a nitrogen atmosphere to obtain Ru / La2O3-ZrO2 (loading amount: 5 mass%).

[0029] (Example 2 Solid Catalyst) Ru / ZrO2-Al2O3 was prepared by the incipient-wetness method. (1) 0.9542 g of ZrO2-Al2O3 (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd. (mass ratio [(ZrO2) / (Al2O3)] = 10 / 90)) was added to a 100 mL beaker. 3.3251 g of Ru precursor solution was added to a 5 mL sample bottle. Next, Ru / ZrO2-Al2O3 (loading amount: 5 mass %) was obtained by carrying out the same operations as in (2) and (3) of Example 1, except that La2O3-ZrO2 was changed to ZrO2-Al2O3.

[0030] (Example 3 Solid Catalyst) Ru / ZrO2-CeO2 was prepared by the incipient-wetness method. (1) 0.9542 g of ZrO2-CeO2 (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd. (mass ratio [(ZrO2) / (CeO2)] = 15.2 / 84.8)) was calcined at 1073 K for 3 hours in a nitrogen atmosphere and added to a 100 mL beaker. 3.3251 g of Ru precursor solution was also added to a 5 mL sample bottle. Next, Ru / ZrO2-CeO2 (loading amount: 5 mass%) was obtained by carrying out the same operations as in (2) to (3) of Example 1, except that La2O3-ZrO2 was replaced with the ZrO2-CeO2 obtained above.

[0031] (Comparative Example 1: Solid Catalyst) Ru / CeO2 was prepared by the incipient-wetness method. (1) Specifically, CeO2 (HS manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) was calcined at 873 K for 3 hours in a nitrogen atmosphere, and 0.9542 g of this CeO2 was added to a 100 mL beaker. Also, 3.3251 g of the Ru precursor solution was added to a 5 mL sample bottle. (2) Next, while heating CeO2 to a temperature in the range of 353 to 363 K using a hot stirrer, the Ru precursor solution was added little by little and mixed thoroughly based on the incipient-wetness method to allow the Ru precursor solution to be supported. (3) After removing the moisture on a hot stirrer, the sample was dried overnight in an oven at 383 K and then calcined at 573 K for 1 hour (heating rate: 20 K / min) in a nitrogen atmosphere to obtain Ru / CeO (loading amount: 5 mass%).

[0032] (Test Example 1) Hydrogenolysis of polyethylene was carried out in the presence of ethyl sulfide as a catalyst poison. That is, the types and amounts of solid catalysts shown in Table 1, polyethylene (M n =1700, M w 3.4 g of ethanol (=4000), ethyl sulfide in the amount shown in Table 1, and a glass stirrer were placed in an inner glass cylinder and introduced into the reactor. Next, the reactor was purged with hydrogen (1 MPa) three times, and hydrogen was introduced so that the hydrogen pressure during the reaction was 6 MPa. After that, the temperature was raised to 240°C, and once it reached 240°C, it was heated for the time shown in Table 1. The reactor was then cooled to room temperature in a water bath, and all gas was removed from the reactor using a gas bag. 40 μL of dichloromethane was introduced into the gas bag containing the gas as an internal standard. Additionally, 100 mg of 9,10-dihydroanthracene was dissolved in 10 g of mesitylene as an internal standard and added to the reactor to recover the liquid phase. If any solid remained, ultrasonic irradiation was performed at approximately 303 K for 10 minutes. The GC sample was filtered through a membrane filter and collected. The solid was also recovered by vacuum filtration and weighed. The recovered gas (vapor phase) and liquid phase were analyzed using a GC-FID (Shimadzu GC-2014). The conversion rate (%) and the yield (%) of C5-21 liquid oil are shown in Table 1. The conversion rate was calculated by considering the solid component remaining after the reaction as the unreacted substrate.

[0033] [Table 1]

[0034] (Test Example 2) Hydrogenolysis of polyethylene was carried out in the presence of triphenyl phosphite as a catalyst poison. That is, polyethylene hydrocracking was carried out in the same manner as in Test Example 1, except that the types and amounts of the solid catalyst and catalyst poison (triphenyl phosphite) were changed to those shown in Table 2. The conversion rate (%) and the yield (%) of C5-21 liquid oil are shown in Table 2.

[0035] [Table 2]

[0036] (Test Example 3) Hydrogenolysis of polyethylene was carried out using the solid catalysts of Examples 1 to 3 without adding ethyl sulfide or triphenyl phosphite as catalyst poisons. That is, except that the type and amount of the solid catalyst were changed to those shown in Table 3 and ethyl sulfide was not used, hydrocracking of polyethylene was carried out in the same manner as in Test Example 1. The conversion rate (%) and the yield (%) of C5-21 liquid oil are shown in Table 3.

[0037] [Table 3]

Claims

1. A solid catalyst for decomposing plastics, comprising a support and ruthenium supported on the support, the support being a composite metal oxide.

2. 2. The solid catalyst according to claim 1, wherein the composite metal oxide is a composite metal oxide containing zirconium dioxide.

3. 2. The solid catalyst according to claim 1, wherein the composite metal oxide comprises zirconium dioxide and at least one selected from the group consisting of oxides of Group 13 metals and oxides of lanthanoids.

4. 2. The solid catalyst according to claim 1, wherein the composite metal oxide is a composite metal oxide containing zirconium dioxide and at least one selected from the group consisting of aluminum oxide, lanthanum (III) oxide, and cerium (IV) oxide.

5. A method for producing a liquid oil, comprising a hydrocracking step of heat-treating a plastic-containing material in the presence of the solid catalyst according to any one of claims 1 to 4 under a hydrogen atmosphere.

6. The method according to claim 5 , wherein the temperature of the heat treatment is in the range of 100° C. or more and 350° C. or less.

7. The method according to claim 5, wherein the plastic-containing material further contains at least one selected from the group consisting of sulfur, sulfur compounds, phosphorus, and phosphorus compounds.

8. The method of claim 5 , wherein the plastic is a polyolefin.

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