Method for treating rubber composition

Abstract

The purpose of the present invention is to provide a treatment method by which a rubber composition can be efficiently decomposed and which makes it possible to attain a reduction in waste amount and the utilization / high-level utilization of resources. This method for treating a rubber composition includes heating the rubber composition to generate a gas including one or more gases selected from the group consisting of hydrogen, carbon monoxide, and carbon dioxide and bringing a catalyst into contact with the rubber composition and / or the gas, wherein the catalyst is either waste containing a metallic element or unutilized resources containing a metallic element.

Description

Method for processing rubber compositions

[0001] The present invention relates to a method for processing rubber compositions.

[0002] In rubber products, chemical reactions and interactions with various compounding agents, including intermolecular crosslinking, are considered essential for the rubber's characteristic viscoelasticity. However, these chemical reactions and interactions are one of the reasons why material recycling and chemical recycling of rubber products are difficult.

[0003] Furthermore, it is difficult to use general recycling processes applicable to resins when recycling rubber products. There are several reasons for this, but the biggest reason in the case of vulcanized rubber is that the manufacturing process requires a process of covalently crosslinking polymers. Unless intermolecular crosslinking is eliminated, recycled rubber products cannot have the same quality as virgin rubber. Currently available recycled rubber is used by processing it to the point where it can be mixed with virgin rubber through non-selective molecular cleavage using physical or chemical methods. For example, Patent Document 1 describes a method of desulfurizing sulfur-crosslinked rubber by contacting it with hydrogen plasma. Also, Patent Document 2 describes that chemical products can be manufactured by thermal decomposition and hydrodecomposition of rubber waste such as waste tires.

[0004] On the other hand, ash, seashells, and oyster shells are used in agriculture as fertilizers and soil conditioners, and in construction and civil engineering as aggregates for cement.

[0005] Japanese Patent Publication No. 2025-031051 Japanese Patent Publication No. 2023-109380

[0006] However, the recycled material obtained from rubber using the method described in Patent Document 1 has inferior performance compared to virgin material, and this method is not practical for achieving horizontal recycling such as PET bottles. Furthermore, rubber gasification, such as the method described in Patent Document 2, has the problem of being slower and more time-consuming compared to the gasification of materials other than rubber, such as plastics and biomass. For this reason, research into rubber gasification has not progressed and it has not been put into practical use. Moreover, since large amounts of ash are produced in various industries and households, new uses are being sought in addition to existing uses. The present invention aims to provide a processing method that can efficiently decompose rubber compositions and also realize waste reduction and the effective utilization and advanced use of resources.

[0007] The present invention provides the following [1] to

[22] : [1] A method for treating a rubber composition, comprising heating the rubber composition to generate a gas containing one or more elements selected from the group consisting of hydrogen, carbon monoxide and carbon dioxide, and contacting the rubber composition and / or the gas with a catalyst, wherein the catalyst is waste or unused resources containing a metal element. [2] The method according to [1], wherein the metal element contains an alkali metal element and / or an alkaline earth metal element. [3] The method according to [2], wherein the alkali metal element contains sodium and / or potassium. [4] The method according to [2], wherein the alkaline earth metal contains calcium and / or magnesium. [5] The method according to any one of [1] to [4], wherein the catalyst contains one or more elements selected from the group consisting of metal chlorides, oxides, carbonates, hydroxides, nitrates and sulfates. [6] The method according to any one of [1] to [5], wherein the waste is waste containing calcium carbonate and / or calcium oxide. [7] The method according to any one of [1] to [6], wherein the waste comprises one or more selected from the group consisting of seashells, eggshells, ash, and coral. [8] The method according to any one of [1] to [7], wherein the heating temperature is 600°C or higher. [9] The method according to any one of [1] to [8], wherein the weight ratio of hydrogen gas to the gas is 20 to 70% by weight.

[10] The method according to any one of [1] to [9], wherein the rubber composition is a rubber composition containing carbon black.

[11] The method according to any one of [1] to

[10] , wherein the rubber composition is rubber waste.

[12] The method according to any one of [1] to

[11] , wherein a catalyst is added to the rubber composition and the resulting mixture is heated.

[13] The method according to any one of [1] to

[11] , wherein the rubber composition is introduced into a heating device containing a catalyst and the rubber composition is heated together with the catalyst.

[14] The method according to any one of [1] to

[11] , wherein the rubber composition is introduced into a fluidized bed heating apparatus equipped with a fluidized medium containing a catalyst, and the rubber composition is heated together with the catalyst.

[15] The method according to any one of [1] to

[11] , wherein the rubber composition is introduced into a fluidized bed heating apparatus equipped with a mixture of a catalyst and fluidized sand, and the rubber composition is heated together with the catalyst.

[16] The method according to any one of [1] to

[11] , wherein the catalyst is brought into contact with a gas.

[17] A method for recycling a rubber composition, comprising heating the rubber composition to generate a gas containing one or more selected from the group consisting of hydrogen, carbon monoxide, and carbon dioxide, and contacting the rubber composition and / or the gas with a catalyst, wherein the catalyst is waste or unused resources containing metal elements.

[18] The method according to

[17] , further comprising purifying the generated gas to obtain a purified gas, and / or synthesizing a recycled material from the gas.

[19] The method according to

[18] , further comprising culturing the generated gas and / or the purified gas with microorganisms to synthesize a recycled material which is one or more selected from the group consisting of isoprene-containing terpenes, polyisoprenes, ethanol, methane, and methanol.

[20] The method according to

[18] , further comprising burning the generated gas and / or the purified gas and utilizing the combustion energy as fuel.

[21] A method for producing gas, comprising heating a rubber composition to generate a gas containing one or more elements selected from the group consisting of hydrogen, carbon monoxide, and carbon dioxide, and contacting the rubber composition and / or gas with a catalyst, wherein the catalyst is waste or unused resources containing metal elements.

[22] A method for producing recycled materials, comprising heating a rubber composition to obtain a gas containing one or more elements selected from the group consisting of hydrogen, carbon monoxide, and carbon dioxide, contacting the rubber composition and / or gas with a catalyst, and synthesizing recycled materials from the generated gas, wherein the catalyst is waste or unused resources containing metal elements.

[0008] According to the processing method of the present invention, the gasification of the rubber composition can be promoted by using a catalyst (for example, the gasification start temperature can be lowered), thus enabling efficient processing of the rubber composition. Furthermore, since waste containing metal elements or unused resources are used as the catalyst, waste reduction and the effective utilization and advanced use of resources can be achieved.

[0009] Figure 1 is a graph showing the results of the gas analysis test in the example.

[0010] [1. Rubber Composition] The subject of the present invention is a rubber composition. The rubber composition may be any composition containing at least a rubber component, or it may be a rubber component alone. The rubber component may be natural rubber or synthetic rubber, and examples include polyisoprene, hydrogenated polyisoprene, polybutadiene, styrene-butadiene copolymer, isobutylene-isoprene copolymer, ethylene-propylene copolymer, ethylene-propylene-diene ternary copolymer, silicone, etc. The rubber component may be vulcanized rubber or unvulcanized rubber.

[0011] The rubber composition may contain components other than rubber. Examples of such components include reinforcing materials such as carbon black, talc, mica, and silica, and inorganic metals such as iron, aluminum, copper, tin, lead, zinc, gold, silver, and stainless steel. Of these, carbon black is often added in large quantities to general rubber products and is a factor in gasification delay (for example, by increasing the temperature required for gasification). The rubber composition may be a substantially mixed and integrated mixture of rubber components and other components, or it may be a so-called rubber-based composite component (such as vibration-damping rubber, hoses, tires, wire harnesses) that includes a rubber component mainly composed of rubber and a component mainly composed of other components.

[0012] The rubber composition is preferably rubber waste. In this specification, rubber waste refers to unwanted rubber compositions, and does not include used products, surplus products (including raw materials and intermediates), substandard products, or waste from industrial production. Examples of rubber waste include used tires; used engine mounts, suspension bushings, rubber hoses, muffler hangers, rubber stoppers, vibration-damping rubber, sealing materials, belt materials, dampers for housing, and waste from photocopiers such as rolls and blades; rubber scraps such as cutting scraps and ebonite scraps; and waste from rubber-related industries (rubber production, rubber recycling, etc.) (for example, by-products such as charred materials generated in rubber manufacturing and carbon residues generated in rubber thermal decomposition), and includes waste materials classified as waste plastics.

[0013] [2. Method for Processing the Rubber Composition] The method for processing the rubber composition includes heating the rubber composition to generate a gas containing one or more elements selected from the group consisting of hydrogen, carbon monoxide, and carbon dioxide, and contacting the rubber composition and / or the gas with a catalyst. The following describes each step accordingly.

[0014] [2.1 Heating of Rubber Composition] The heating conditions for the rubber composition are not particularly limited, but according to one embodiment, the heating temperature is preferably 600°C or higher, 650°C or higher, more preferably 700°C or higher, 750°C or higher, and even more preferably 800°C or higher, 850°C or higher, 900°C or higher, and 950°C or higher. This allows the rubber composition to be thermally decomposed. The upper limit is preferably 1300°C or lower, more preferably 1200°C or lower, and even more preferably 1150°C or lower, 1100°C or lower, 1050°C or lower, and 1000°C or lower. This increases the amount of hydrogen, carbon monoxide, carbon dioxide, etc. produced and improves the gasification efficiency. Therefore, temperatures of 600 to 1300°C and 650 to 1300°C or higher are preferred, 700 to 1200°C and 750 to 1200°C are more preferred, and 800 to 1150°C, 850 to 1100°C, 900 to 1050°C, and 950 to 1000°C are even more preferred.

[0015] Heating is preferably carried out under a reducing atmosphere. In this specification, heating under a reducing atmosphere means that oxygen (O) in the system is reduced. ２ ), hydrogen (H ２ ), carbon dioxide (CO ２ ), and water (H ２ This means adjusting the amount of at least one of the following to accelerate chemical reactions and regulate oxidation-reduction within the system. For example, by supplying oxygen, water, carbon dioxide, etc., to the system and adjusting their ratio, the chemical reactions of the rubber composition can be accelerated, and as a result, the total amount of generated gas can be increased. Furthermore, by utilizing surplus products and exhaust gases for supply to the system, operating efficiency can be improved and carbon dioxide emissions can be reduced. On the other hand, the reduction of the rubber composition can be accelerated, and the proportion of hydrogen gas in the total gas volume can be increased.

[0016] Heating may be performed intermittently or continuously, multiple times. This allows for the acquisition of a high-purity gas and improves gasification efficiency.

[0017] The gas produced by heating is hydrogen (H ２ ), carbon monoxide (CO) and carbon dioxide (CO) ２ It contains one or more selected from the group consisting of ). The ratio of hydrogen, carbon monoxide, and carbon dioxide is not particularly limited, but the ratio of hydrogen gas to the total amount of gas is preferably 20 to 70% by weight, more preferably 25 to 65% by weight, and even more preferably 30 to 60% by weight. The gas obtained in the heating step may contain other components other than hydrogen, carbon monoxide, and carbon dioxide. Examples of other components include hydrocarbons (e.g., C1 to C4 organic component gases (e.g., methane gas, ethylene gas, ethane gas, propylene gas, propane gas, isobutane gas, n-butane gas), acetylene gas, and other hydrocarbon gases), hydrogen sulfide gas, sulfur oxide gas, hydrogen chloride gas, nitrogen oxide gas, oxygen gas, oil, tar, and soot. It is preferable that the content of other components be low, and more preferably substantially absent (e.g., 10% by weight or less, 8% by weight or less, 5% by weight or less, 3% by weight or less, 1% by weight or less, 0.1% by weight or less, 0.01% by weight or less, below the detection limit).

[0018] [2.2 Contact of catalyst with rubber composition and / or gas] The catalyst contains a metal element and is a waste or underutilized resource. By using such a substance as a catalyst, the gasification of the rubber composition can be promoted.

[0019] Any element with metallic properties can be used as a metallic element, such as alkali metals, alkaline earth metals, or transition elements, with alkali metals and alkaline earth metals being preferred. Examples of alkali metals include sodium, potassium, lithium, rubidium, and francium, with sodium and potassium being preferred. Examples of alkaline earth metals include magnesium, calcium, beryllium, strontium, barium, and radium, with magnesium and calcium being preferred. Examples of transition elements include manganese, iron, copper, titanium, zinc, cobalt, nickel, scandium, vanadium, and chromium, with manganese and iron being preferred. These metallic elements may exist in their elemental form, or they may be bonded with other elements through ionization or other means. Other elements include carbon, oxygen, silicon, phosphorus, sulfur, chlorine, and nitrogen. Examples of compounds formed by bonding with metallic elements include chlorides, carbonates, hydroxides, nitrates, sulfates, and oxides (e.g., calcium carbonate, calcium oxide).

[0020] The waste and unused resources may contain metallic elements, and their origin and source are not particularly limited (for example, they may be industrial waste and unused resources such as by-products, residues, and surplus raw materials in the manufacturing and processing processes of intermediate or final products in agriculture, industry, etc., or they may be waste and unused resources such as household garbage and expired products). Furthermore, their form is not particularly limited to solid or liquid. Examples of solids include powders (for example, shell powder such as oyster shell powder, and ash). This allows for efficient contact between the rubber composition and the catalyst, thereby increasing the gas generation efficiency.

[0021] Examples of waste and underutilized resources containing metallic elements include seashells (e.g., oyster shell powder), eggshells (e.g., eggshell powder), and ash (e.g., wood ash, straw ash, volcanic ash, diatomaceous earth ash; unutilized biomass, biomass waste, incineration ash derived from scraps; incineration ash discharged from factories, power plants, etc.), and coral. One, two, or all of seashells, ash, and eggshells are preferred, with ash being more preferred. In other embodiments, one, two, or all of oyster shell powder, eggshell powder, and ash are preferred, one or more selected from oyster shell powder, eggshell powder, wood ash, wood ash, and straw ash are more preferred, one or more selected from eggshell powder, wood ash, wood ash, and straw ash are even more preferred, and one or more selected from wood ash, wood ash, and straw ash are even more preferred.

[0022] Other catalysts may be used in combination with the catalyst described above. Examples of other catalysts include nickel-based catalysts such as nickel and nickel oxide, ruthenium-based catalysts, iron-based catalysts, cobalt-based catalysts, titanium-based catalysts, and oxide-based catalysts.

[0023] The catalyst can be brought into contact with either the rubber composition, the generated gas, or both in an effective amount. Examples of its use in the heating process include contacting and / or mixing the rubber composition and the catalyst before heating; adding the catalyst after heating the rubber composition (during heating to a desired temperature, or after reaching a desired temperature) and bringing it into contact and / or mixing it with the rubber composition; and adding the catalyst after heating the catalyst (during heating to a desired temperature, or after reaching a desired temperature) and bringing it into contact and / or mixing it with the rubber composition. An example of its use in the recovery process is bringing the catalyst into contact with the recovered gas continuously or sequentially.

[0024] [2.3 Heating Equipment] The above process can be carried out using a heating equipment. Examples of heating and recovery equipment include fluidized bed type, jet bed type, kiln type, shaft type, and fixed bed type heating and recovery equipment (e.g., gasification furnaces); and extruders equipped with gas recovery means, with fluidized bed type heating and recovery equipment being preferred. This can increase reaction efficiency and achieve efficient gasification. Examples of fluidized bed type heating and recovery equipment include equipment equipped with a fluidized bed composed of a fluidized medium (e.g., fluidized sand) and a gas recovery channel. When a catalyst is used in the process, the timing of its addition is not particularly limited. For example, the following addition methods are possible: adding the catalyst to the rubber composition before heating and mixing, then introducing the resulting mixture into the heating equipment and heating it; storing the catalyst in the heating equipment and introducing the rubber composition into it and heating it; and contacting the catalyst with the gas generated in the heating equipment.

[0025] When using a heating device, the catalyst may be pre-installed in the heating device (for example, inside the heating furnace or inside the gas recovery channel), or the catalyst may be added to the rubber composition before it is introduced into the heating device, or to the gas after it has been recovered from the device, or both. For example, one method is to mix the catalyst with a fluidized medium such as fluidized sand in a fluidized bed heating device, and then introduce the rubber composition into the device and heat the rubber composition together with the catalyst. Alternatively, the catalyst and rubber composition may be mixed to prepare a mixture, and the resulting mixture may be introduced into the heating device and heated. Furthermore, for example, a catalyst layer containing the catalyst may be pre-installed in any part of the gas channel of the heating device, and the gas may come into contact with the catalyst by passing through the catalyst layer as it flows through the channel.

[0026] [2.4 Applications] According to the processing method of the present invention, gasification can be promoted by using a catalyst (for example, the gasification start temperature can be lowered), so rubber compositions can be processed efficiently. Therefore, it can be used for recycling rubber compositions.

[0027] [3. Recycling Methods] Examples of recycling methods using the above processing methods include gas production methods and recycled material production methods.

[0028] [3.1 Method for Producing Gas] According to the above processing method, a gas containing one or more elements selected from the group consisting of hydrogen, carbon monoxide, and carbon dioxide can be produced. The produced gas can be used in various industries. Examples of applications include power generation, production of renewable fuels (heat sources) (e.g., fuel for transport vehicles such as automobiles, ships, and aircraft, and industrial fuel for heating furnaces, etc.), and production of recycled materials.

[0029] The gas obtained by the above processing method may be subjected to a purification treatment. This can reduce the impurity content and increase the proportions of hydrogen, carbon monoxide, and carbon dioxide, preferably increasing the proportion of hydrogen. Examples of purification treatments include gas purification treatments such as absorption treatment with a solution, adsorption treatment on a solid, and permeation treatment on a membrane, and appropriate methods and conditions can be selected.

[0030] [3.2 Method for Producing Recycled Materials] Various recycled materials can be produced using the gas produced by the above processing method as a raw material. Examples of recycled materials include hydrocarbons such as methane, ethane, and naphtha; alcohols such as methanol and ethanol; terpenes such as isoprene; ammonia; and various polymer compounds (e.g., polyisoprenes) that utilize these as raw materials.

[0031] In the production of recycled materials, organic chemical reactions and microorganisms can be used, but the use of microorganisms is preferred. It is preferable to use at least microorganisms capable of producing recycled materials or their raw materials by utilizing (assimilating) the above-mentioned gases. Examples include photosynthetic bacteria such as acetic acid-producing bacteria and microalgae, hydrogen bacteria, isoprene, and butadiene-producing bacteria. Specifically, these include Moorella (e.g., Moorella thermoacetica), Clostridium (e.g., Clostridium autoethanogenum, Clostridium ljungdahlii, Clostridium carbonixidivorans), Ruminococcus, Acetobacterium (e.g., Acetobacterium woodii), and Eubacterium (e.g., Eubacterium) Examples include limosum, butyribacterium (e.g., Butyribacterium methylotropicum), oxobacter, Methanosarcina, Desulfotomaculum, and Saccharomyces. Furthermore, examples include microorganisms into which genes related to the production of recycled materials or their raw materials (e.g., isoprene synthase genes) have been introduced (e.g., Escherichia coli, methane-assimilating bacteria (e.g., Methylococcus, Methylomonas, Methylosinus, Methylocystis, Methylobacter, Methylobacterium, Methylocella, Methylocystis, Methylocapsa, Methylacidiphilum, Methylocida, Methylibium, Methylomicrobium bacteria)). The culture conditions for the microorganisms should be appropriately set to conditions suitable for the growth of the microorganisms used.

[0032] [3.3 Method of utilizing combustion energy] The gas produced by the above processing method can be used as fuel for power generation, heating furnaces, etc., due to its combustion energy. For example, in the case of power generation, the combustion energy can be used to drive a gas turbine.

[0033] The present invention will be described by way of examples. The following examples show an example of the present invention and do not limit the present invention.

[0034] Example 1 and Comparative Example 1 (Gasification Test) A dish-shaped alumina sample cup (alumina boat) was spread with rubber pieces (NR rubber (vulcanized rubber)) (total weight: 25 mg), and 25 mg of wood ash (component ratio (average value of elemental analysis at three sites) is as shown in Table 1) was placed thereon to cover the rubber pieces (rubber pieces: wood ash (mass ratio)=1:1, total 50 mg). TG-DTA measurement was performed in an atmosphere into which water vapor was introduced (using a thermogravimetry-differential thermal analyzer (STA2500 (manufactured by NETZSCH))). The temperature conditions were set as increasing at 20°C / min to 1000°C, followed by holding at 1000°C for 60 minutes. The atmosphere conditions were H ２ O: 10 vol%, N ２ : 90 vol% (Example 1). On the other hand, the measurement was carried out in the same manner as in Example 1 except that only rubber pieces were placed in the sample cup (Comparative Example 1).

[0035]

[0036] As a result, the gasification starting temperature in Example 1 was about 800°C, which was lowered by 100°C or more compared to about 900°C in Comparative Example 1 (Table 2). While wood ash contains various metal elements, the content of these metal elements in the rubber composition is relatively small, so it is presumed that in Example 1, the addition of wood ash allowed the metal elements to act to promote gasification.

[0037]

[0038] Reference Examples 1 to 3 (Examination of Catalyst Candidates) Elemental analysis was performed on straw ash, plant ash, and oyster shell powder (Table 3)

[0039]

[0040] All samples contain various metal elements, and the same catalytic effect as that of the wood ash used in Example 1 can be expected.

[0041] Examples 2 to 3 and Comparative Examples 2 to 4 (Gas Analysis Test) In order to confirm the effect of adding wood ash and oyster shell powder on the thermal decomposition of rubber, a gas analysis test after thermal decomposition was performed according to the following procedure.

[0042] As a pyrolysis apparatus, a pyrolysis apparatus equipped with an alumina core tube (inner diameter 50 mm × length 1500 mm) and a horizontal tubular furnace provided so as to cover the central portion in the length direction of the core tube was prepared. The temperature of the core tube was raised to 1000°C by the horizontal tubular furnace and maintained, and N from a cylinder was supplied into the core tube from one end side (inlet side) of the core tube ２ gas was supplied under the control of an MFC, and distilled water was also supplied as water vapor via a vaporizer, whereby the inside of the core tube was adjusted to 10% by volume of water vapor and O ２ gas 0% by volume, N ２ gas 90% by volume, H ２ O gas was adjusted to an atmosphere (reducing atmosphere) of 10% by volume. The atmosphere flow rate was 5 L / min.

[0043] Rubber particles having a maximum length of about 1.5 cm (same as in Example 1) spread on an alumina boat (same as in Example 1) (Comparative Examples 2 and 5), and those sprinkled with wood ash or oyster shell powder so as to cover the rubber particles (Examples 2 and 3), and those with wood ash or oyster shell powder spread on an alumina boat without placing rubber particles (Comparative Examples 3 and 4) were prepared, and each of these (the weight of the sample on the alumina boat was 2 g in all cases) was inserted into the core tube (and the horizontal tubular furnace) from the inlet side of the core tube, heated to 1200°C at a heating rate of 10°C / min, and pyrolyzed for 21 minutes to be gasified.

[0044] The produced gas generated as a result of pyrolysis and gasification of each sample was led out from the other end side (outlet side) of the core tube and collected in a gas bag by a pump. The weight of the produced gas obtained from each sample was measured, and analysis was performed by the following analysis method (Table 4, Figure 1).

[0045] [Method for analyzing produced gas] H ２ , CO, CO ２ : gas chromatography (TCD)

[0046]

[0047] [Footnote to Table 4] *1: Total amount of Comparative Examples 2 and 3 *2: Total amount of Comparative Examples 2 and 4

[0048] The amount of gas generated in Examples 2 and 3 (rubber with wood ash and oyster shells added) was considerably higher than in Comparative Example 2 (rubber alone). This suggests that the wood ash and oyster shells acted as catalysts to accelerate the reaction, resulting in increased carbon gasification.

[0049] The fact that Comparative Examples 3 and 4 (wood ash alone and oyster shells alone) produced zero or only a small amount of gas, and that the gas production in the two reference examples (comparative examples 2 and 3, and the combined amount of comparative examples 2 and 4) was largely less than that of Examples 2 and 3, indicates that the effects in Examples 2 and 3 were unexpectedly significant.

[0050] The results of the above examples demonstrate that the present invention enables the gasification of rubber compositions at lower temperatures using a catalyst, thereby promoting the recycling of rubber compositions while further reducing the environmental impact.

Claims

1. A method for treating a rubber composition, comprising: heating the rubber composition to generate a gas containing one or more elements selected from the group consisting of hydrogen, carbon monoxide, and carbon dioxide; and contacting the rubber composition and / or gas with a catalyst, wherein the catalyst is waste or unused resources containing metallic elements, and the waste or unused resources containing metallic elements include ash.

2. The method according to claim 1, wherein the metallic element includes an alkali metal element and / or an alkaline earth metal element.

3. The method according to claim 2, wherein the alkali metal element includes sodium and / or potassium.

4. The method according to claim 2, wherein the alkaline earth metal comprises calcium and / or magnesium.

5. The method according to any one of claims 1 to 4, wherein the catalyst comprises one or more selected from the group consisting of metal chlorides, oxides, carbonates, hydroxides, nitrates, and sulfates.

6. The method according to any one of claims 1 to 5, wherein the waste is waste containing calcium carbonate and / or calcium oxide.

7. The method according to any one of claims 1 to 6, wherein the waste further comprises one or more selected from the group consisting of seashells, eggshells, and coral.

8. The method according to any one of claims 1 to 7, wherein the heating temperature is 600°C or higher.

9. The method according to any one of claims 1 to 8, wherein the weight ratio of hydrogen gas to the gas is 20 to 70% by weight.

10. The method according to any one of claims 1 to 9, wherein the rubber composition is a rubber composition containing carbon black.

11. The method according to any one of claims 1 to 10, wherein the rubber composition is rubber waste.

12. The method according to any one of claims 1 to 11, comprising adding a catalyst to a rubber composition and heating the resulting mixture.

13. The method according to any one of claims 1 to 11, wherein a rubber composition is introduced into a heating device containing a catalyst, and the rubber composition is heated together with the catalyst.

14. The method according to any one of claims 1 to 11, comprising introducing a rubber composition into a fluidized bed heating apparatus equipped with a fluidized medium containing a catalyst, and heating the rubber composition together with the catalyst.

15. The method according to any one of claims 1 to 11, wherein a rubber composition is introduced into a fluidized bed heating apparatus equipped with a mixture of a catalyst and fluidized sand, and the rubber composition is heated together with the catalyst.

16. The method according to any one of claims 1 to 11, wherein a catalyst is brought into contact with a gas.

17. A method for recycling a rubber composition, comprising heating the rubber composition to generate a gas containing one or more elements selected from the group consisting of hydrogen, carbon monoxide, and carbon dioxide, and contacting the rubber composition and / or gas with a catalyst, wherein the catalyst is waste or unused resources containing metallic elements, and the waste or unused resources containing metallic elements include ash.

18. The method according to claim 17, further comprising purifying the generated gas to obtain purified gas, and / or synthesizing recycled material from the gas.

19. The method according to claim 18, further comprising culturing the generated gas and / or purified gas with microorganisms to synthesize a recycled material which is one or more selected from the group consisting of isoprene-containing terpenes, polyisoprenes, ethanol, methane, and methanol.

20. The method according to claim 18, further comprising burning the generated gas and / or purified gas and utilizing the combustion energy as fuel.

21. A method for producing gas, comprising heating a rubber composition to generate a gas containing one or more elements selected from the group consisting of hydrogen, carbon monoxide, and carbon dioxide, and contacting the rubber composition and / or gas with a catalyst, wherein the catalyst is waste or unused resources containing metal elements, and the waste or unused resources containing metal elements include ash.

22. A method for producing recycled material, comprising: heating a rubber composition to obtain a gas containing one or more elements selected from the group consisting of hydrogen, carbon monoxide, and carbon dioxide; contacting the rubber composition and / or gas with a catalyst; and synthesizing recycled material from the generated gas, wherein the catalyst is waste or unused resources containing metal elements, and the waste or unused resources containing metal elements include ash.

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