Metal carbide and method for producing metal carbide

Abstract

[Problem] To provide a metal carbide and a method for producing a metal carbide with which a bioplastic raw material can be relatively inexpensively and stably supplied. [Solution] One aspect of the present invention provides a metal carbide having a biomass degree of 0.01% to 100% as measured by the 14C isotope measurement method defined in ASTM D6866.

Description

Metal carbide and method for producing metal carbide

[0001] The present invention relates to metal carbides and methods for producing metal carbides.

[0002] In recent years, there has been an increasing demand for bioplastics in order to reduce the burden on the environment. Biopolyethylene has been put on the market as a bioplastic, and it is expected to contribute to reducing carbon dioxide emissions (see Patent Document 1). This biopolyethylene is produced from ethylene obtained using bionaphtha and the like.

[0003] However, bionaphtha is produced from waste materials and residues such as used cooking oil, and its supply is limited. Research is also underway to obtain bioethanol from wood, a non-edible biomass, and then produce ethylene from this bioethanol. However, in both of these cases, the raw materials are denatured by fermentation, making it difficult to significantly reduce costs.

[0004] JP 2010-511634 A

[0005] In view of the above circumstances, the present invention provides a metal carbide that can provide a relatively inexpensive and stable supply of raw materials for bioplastics, and a method for producing the metal carbide.

[0006] According to one aspect of the present invention, a metal carbide as defined in ASTM D6866 is １４ There is provided a metal carbide having a biomass ratio of 0.01% or more and 100% or less as measured by C isotope measurement.

[0007] According to this embodiment, raw materials for bioplastics can be supplied relatively cheaply and stably.

[0008] Hereinafter, embodiments of metal carbide and a method for manufacturing the same will be described. Various features shown in the following embodiments can be combined with each other.

[0009] <Metal Carbide> The metal carbide of this embodiment is defined in ASTM D6866. １４The biomass ratio measured by C isotope measurement is about 0.01% or more and 100% or less. Metal carbide has the chemical formula: MC or MC ２ (M is a metal atom), and is used, for example, as a convenient source of acetylene. Furthermore, acetylene can be used to obtain industrially important compounds (e.g., 2-chloro-1,3-butadiene: chloroprene monomer) that serve as raw materials for various plastics. Therefore, metal carbides having the above-mentioned biomass ratios can provide a relatively inexpensive and stable supply of raw materials for bioplastics.

[0010] Here, the biomass ratio means the ratio of carbon atoms derived from biomass contained in the metal carbide. This biomass ratio is determined by the radiocarbon ( １４ The biomass content can be determined by measuring the amount of C) contained in the metal carbide. １４ Accelerator Mass Spectrometry (AMS), a type of C isotope measurement method, was used to measure the carbon content of all carbon atoms contained in the metal carbide. １４ The percentage of carbon (percent modern carbon: pMC) is measured, and the percentage (content) of carbon atoms derived from biomass is calculated.

[0011] The biomass degree may be about 0.01% or more and 100% or less, preferably about 0.1% or more and 80% or less, and more preferably about 1% or more and 60% or less. If the biomass degree is set to the upper limit or less, the raw material for bioplastics can be supplied more cheaply. On the other hand, if the biomass degree is set to the lower limit or more, it is easier to contribute to the realization of a carbon-recycling society.

[0012] Metal carbides are preferably used to produce acetylene. This is because acetylene (bioacetylene) can be used to produce industrially important compounds that serve as raw materials for various plastics (bioplastics). For example, ethylene can be produced by hydrogenating acetylene, acrylonitrile by reacting acetylene with hydrogen cyanide, vinyl chloride by reacting acetylene with hydrogen chloride, acrylic acid by reacting acetylene with carbon monoxide and water, monovinylacetylene by dimerization of acetylene, vinyl acetate by reacting acetylene with acetic acid, and acetaldehyde by reacting acetylene with water. Acrylic acid can also produce acrylic esters by reacting with alcohols. Acetylene black can also be produced by thermal decomposition of acetylene.

[0013] Metal carbides (especially calcium carbide) are also preferably used to produce calcium nitrous oxide. Calcium nitrous oxide is primarily composed of calcium cyanamide and also contains calcium oxide. After exerting its pesticide effects (insecticidal, herbicidal, and fungicidal effects), calcium cyanamide decomposes into fertilizer components in the soil, leaving no residue and allowing for safe use. Furthermore, calcium nitrous oxide is less likely to be washed away from the soil and exhibits slow release, allowing for reduced frequency and amount of fertilizer application. The use of calcium nitrous oxide not only improves soil acidity but also promotes the decomposition of organic matter, making it easier to create soil suitable for cultivation. Such calcium nitrous oxide can be produced, for example, by absorbing and combining nitrogen with the calcium carbide at high temperatures.

[0014] The metal carbide reacts with pure water to generate acetylene, and the sulfur atom content in the metal carbide is preferably about 100 ppm or less, more preferably about 90 ppm or less, even more preferably about 80 ppm or less, particularly preferably about 50 ppm or less, and may even be 0 ppm. The metal carbide reacts with pure water to generate acetylene, and the phosphorus atom content in the metal carbide is preferably about 1 ppm to 320 ppm, more preferably about 5 ppm to 250 ppm, even more preferably about 10 ppm to 200 ppm, and particularly preferably about 20 ppm to 180 ppm. The metal carbide reacts with pure water to generate acetylene, and the ash content in the metal carbide is preferably about 10% by mass or less, more preferably about 8% by mass or less, even more preferably about 5% by mass or less, particularly preferably about 3% by mass or less, and may be 0% by mass.

[0015] <Method for Producing Metal Carbide> The above-described metal carbide can be produced, for example, by the following method for producing metal carbide. The method for producing metal carbide of this embodiment includes a step of preparing a carbon source containing biomass and a metal source, and a step of heating the carbon source and the metal source in an electric furnace to obtain the above-described metal carbide. Each step will be described below.

[0016] <<Preparation Step>> First, a carbon source containing biomass and a metal source are prepared. Examples of biomass include plant-derived biomass and animal-derived biomass. These waste materials may be used alone or in combination. Examples of plant-derived biomass include felled trees, sawmill waste, chips, and wood such as branches; agricultural crops such as corn, sugarcane, wheat, rice, soybeans, rapeseed, and sorghum; agricultural residues such as rice straw, wheat straw, corn stalks and leaves, coconut shells, and bagasse (sugarcane pomace); grasses (herbaceous plants) such as switchgrass and miscanthus; algae such as seaweed and microalgae; pulp; lignocelluloses such as lignin; fruit peels, seeds, and vegetable oils. Examples of animal-derived biomass include livestock (cattle, pigs, chickens, etc.) manure, livestock by-products such as livestock bones or organs, and animal oils.

[0017] The biomass may be used after separation using a specific method. For example, lignocellulosic biomass may be prepared as the biomass, and insoluble matter containing lignin (lignin-containing components) may be separated and recovered from the lignocellulosic biomass using a dilute sulfuric acid method or a concentrated sulfuric acid method. The biomass may be used as a carbon source as is, or the carbonized product obtained after carbonization may be used as a carbon source. The fixed carbon content in the carbon source can be adjusted, for example, by controlling the temperature (carbonization temperature) during carbonization of the biomass. Specifically, the fixed carbon (carbon atoms) content in the carbon source is preferably about 85% by mass or more, more preferably about 90% by mass or more, even more preferably about 95% by mass or more, and may even be 100% by mass. In this case, metal carbide with a reduced impurity content can be obtained at a high yield. The fixed carbon content in the carbon source can be measured according to JIS M 8812:2006.

[0018] Among the above, non-edible biomass, particularly carbonized non-edible biomass, is preferred as the biomass. This is because the use of non-edible biomass eliminates the need to consider competition with food. In particular, the biomass preferably contains at least one of charcoal, pulp carbonized, lignin carbonized (carbonized lignin-containing component), coconut shell carbonized, bagasse carbonized, and sorghum carbonized. It is more preferred that the biomass contains charcoal and / or pulp carbonized, and even more preferred that the biomass contains charcoal. Charcoal is easy to obtain and easy to handle, and therefore has the advantage that when used in combination with coke, they can be easily mixed uniformly. Furthermore, charcoal and pulp carbonized materials do not contain phosphorus compounds, or contain only small amounts of them, thereby sufficiently reducing the content of impurities such as calcium phosphide (metal phosphide) in the resulting metal carbide. Therefore, when acetylene is produced using such metal carbides, the generation of toxic substances such as phosphine derived from the above impurities can be suitably prevented, and therefore safety is high.

[0019] Among charcoal, it is preferable to use hard charcoal. The use of hard charcoal makes it difficult to crush when mixed with coke or in the subsequent heating step, facilitating more stable production of metal carbide. Specific examples of charcoal include white charcoal, black charcoal, sawdust charcoal, and industrial charcoal. These charcoal may be used alone or in combination of two or more types. Specifically, it is preferable that a sample of 35 mm x 35 mm x 10 mm cut from the carbon source has a crushing strength of about 30 kgf or more as measured in accordance with JIS Z 8841:1993.

[0020] Briquettes and molded charcoal produced by firing briquettes can also be suitably used as carbon sources. Such briquettes can be obtained by pulverizing and sieving biomass in a pulverizer to obtain pulverized biomass, mixing the pulverized biomass with a binder in a mixer, and then molding the mixture in a molding machine. The crushing strength of these carbon sources is preferably about 30 kgf or more, more preferably about 35 kgf or more, and even more preferably about 40 kgf or more. The upper limit of the crushing strength of the carbon source is not particularly limited, but is about 60 kgf. The crushing strength of the carbon source can be, for example, about 30 kgf or more and 60 kgf or less. This can suitably prevent collapse of the carbon source during charging or in an electric furnace.

[0021] Such a carbon source preferably has a volatile content of about 5% by mass or less, more preferably about 4% by mass or less, and even more preferably about 3% by mass or less, as measured in accordance with JIS M 8812:2006. The lower limit of the volatile content of the carbon source is not particularly limited, but is about 0.01% by mass. The volatile content of the carbon source can be, for example, about 0.01% by mass or more and about 5% by mass or less. This can suitably prevent the carbon source from burning during storage, etc. Furthermore, the content of phosphorus atoms in the carbon source is preferably about 200 ppm or less, more preferably about 150 ppm or less, about 100 ppm or less, about 60 ppm or less, more preferably about 50 ppm or less, and even more preferably about 40 ppm or less. In this case, even when acetylene is produced using the obtained metal carbide, the generation of toxic substances such as phosphine can be sufficiently prevented, thereby further improving safety.

[0022] However, if a small amount of phosphorus atoms is contained in the carbon source, the odor of phosphorus compounds derived from calcium phosphide (metal phosphide) can be detected, thereby making it possible to detect the leakage of highly flammable acetylene. From this perspective, safety can also be improved. Specifically, the content of phosphorus atoms in the carbon source is preferably about 0.1 ppm or more, more preferably about 0.5 ppm or more, about 1 ppm or more, about 5 ppm or more, about 10 ppm or more, about 15 ppm or more, or about 20 ppm or more, more preferably about 25 ppm or more, and even more preferably about 30 ppm or more. The content of phosphorus atoms in the carbon source can be, for example, about 0.1 ppm or more and about 200 ppm or less.

[0023] The content of sulfur atoms in the carbon source is preferably 0.1% by mass (1000 ppm) or less, more preferably about 800 ppm or less, even more preferably about 600 ppm or less, particularly preferably about 400 ppm or less, and most preferably about 200 ppm or less. In this case, the generation of hydrogen sulfide can be suppressed, thereby improving safety. The generation of sulfur oxides can also be suppressed, thereby reducing corrosion and other problems in metal carbide and bioplastic production equipment. The lower limit of the content of sulfur atoms in the carbon source is not particularly limited, but is about 50 ppm. The content of sulfur atoms in the carbon source can be, for example, about 50 ppm or more and 1000 ppm or less. The contents of phosphorus atoms and sulfur atoms in the carbon source can be measured in accordance with JIS M 8813:2004.

[0024] The ash content in the carbon source is preferably about 13% by mass or less, more preferably about 10% by mass or less, even more preferably about 5% by mass or less, and particularly preferably about 3% by mass or less. In this case, even if the ash is a compound that is reduced in an electric furnace, the amount is small, which can suitably prevent or suppress wasteful consumption of the carbon source and electricity. It can also reduce the number of times the work of periodically removing (cleaning) the reduced ash accumulated at the bottom of the electric furnace is required. Furthermore, it can also improve the purity of the metal hydroxide by-product generated when acetylene is generated by reacting metal carbide with water. The lower limit of the ash content in the carbon source is not particularly limited and may be 0% by mass. The ash content in the carbon source can be, for example, about 0% by mass or more and 13% by mass or less. Here, ash refers to the inorganic component residue remaining when the carbon source is completely combusted in air (usually at about 550°C or more and 800°C or less). The ash content in the carbon source can be measured in accordance with JIS M 8812:2006.

[0025] On the other hand, examples of the metal source include alkaline earth metal oxides, alkaline earth metal carbonates, alkaline earth metal hydroxides, alkaline earth metal sulfates, and alkaline earth metal chlorides. These metal sources may be used alone or in combination of two or more. The metal source preferably contains an alkaline earth metal oxide, and more preferably contains calcium oxide. Calcium oxide (CaO) can be, for example, calcium carbonate (CaCO ３ Calcium oxide is an unstable substance obtained by thermal decomposition of calcium carbide (CaO) at approximately 900°C. Calcium oxide is therefore suitable as a metal source due to its high reactivity. Suitable metal carbides include calcium carbide, barium carbide, and magnesium carbide.

[0026] <<Heating Step>> Next, the mixture of the carbon source and the metal source is placed in an electric furnace (carbide electric furnace) and heated. This causes the carbon source and the metal source to react with each other to obtain metal carbide. The heating temperature is not particularly limited, but is preferably about 1700°C or higher and 2200°C or lower, and more preferably about 1900°C or higher and 2100°C or lower. The heating time is also not particularly limited, but when the heating temperature is set as above, it is preferably about 2 minutes to 3 hours, and more preferably about 30 minutes to 1.5 hours. Heating under such heating conditions allows the reaction between the carbon source and the metal source to proceed sufficiently.

[0027] The heating atmosphere is preferably an argon atmosphere. This can prevent unnecessary combustion of carbon monoxide and hydrogen generated during the reaction between the carbon source and the metal source. The amount of carbon source is preferably about 30 parts by mass or more and 400 parts by mass or less, more preferably about 50 parts by mass or more and 300 parts by mass or less, and even more preferably about 70 parts by mass or more and 200 parts by mass or less, relative to 100 parts by mass of the metal source. By carrying out the reaction at such an amount ratio, the yield of metal carbide can be sufficiently increased. The carbon source and the metal source are preferably each in a particulate form. This can increase the contact area between the carbon source and the metal source, thereby improving their reaction efficiency.

[0028] The average particle size of the carbon source is not particularly limited, but is preferably about 8 mm to 50 mm, more preferably about 8 mm to 30 mm, and even more preferably about 8 mm to 10 mm. The average particle size of the metal source is also not particularly limited, but is preferably about 8 mm to 50 mm, more preferably about 8 mm to 30 mm, and even more preferably about 8 mm to 10 mm. In this specification, the average particle size refers to the particle size (D50) at which the cumulative value in the volume-based cumulative particle size distribution obtained by laser diffraction scattering method reaches 50%. The laser diffraction scattering method is measured in accordance with the method described in JIS Z 8825:2013 "Particle size analysis - laser diffraction and scattering method."

[0029] When biomass is used as a carbon source and combined with coke, combustion of the biomass, which has a lower ignition temperature than coke, is initiated first, and the heat from this combustion is expected to promote the combustion of the coke. As a result, the heating temperature can be smoothly adjusted to the above-mentioned range in which the reaction between the carbon source and the metal source proceeds smoothly. This effect is particularly pronounced when charcoal is used as a biomass. Charcoal has a high carbon to hydrogen atom ratio, making it suitable for use in combination with coke. Charcoal is also preferred because it has lower electrical conductivity than coke and is less likely to cause electrical short circuits in an electric furnace. Furthermore, the use of charcoal has the advantage of preventing a significant increase in the production cost of metal carbide, since it does not require significant changes to the electric furnace configuration or the addition of new production equipment.

[0030] Prior to the heating (main heating), the mixture may be preheated at a lower temperature than the heating temperature. Preheating can reduce the consumption of the carbon source during the main heating and increase the yield of metal carbide. Examples of fuel for the preheating include charcoal, which has a low ignition temperature among substances contained in the carbon source, and electric furnace gas (a mixed gas of carbon monoxide and hydrogen) emitted during the main heating. Using charcoal as the fuel for the preheating allows for a smooth transition from preheating to the main heating. Using electric furnace gas as the fuel for the preheating can effectively utilize energy while favorably preventing air pollution. Furthermore, by changing the mixing ratio of biomass (charcoal) to coke in the main heating step, the biomass content of the resulting metal carbide can be adjusted within the above range. Therefore, the mass balance method can appropriately respond to fluctuations in demand by simply changing the mixing ratio of biomass to coke according to the demand for biomass.

[0031] Furthermore, the gas containing at least carbon monoxide and hydrogen produced in the electric furnace during this heating step may be recovered. That is, the method for producing metal carbide may further include a step of recovering the gas containing at least carbon monoxide and hydrogen produced in the electric furnace. The recovered carbon monoxide and hydrogen may be used, for example, as an energy source for converting calcium carbonate to calcium oxide or an energy source for converting metal carbide to acetylene, or may be used to convert them into carbon compounds. In the latter case, the method for producing metal carbide may further include a step of reacting at least carbon monoxide with hydrogen to obtain a carbon compound. This allows for the effective use of gas generated in the metal carbide production step. Examples of such carbon compounds include acrylic acid, olefins (jet fuel), and acetylene black. Furthermore, the method may be provided in the following aspects.

[0032] (1) Metal carbide as defined in ASTM D6866 １４ A metal carbide having a biomass ratio of 0.01% or more and 100% or less as measured by a C isotope measurement method.

[0033] (2) The metal carbide according to (1) above, which is used to produce acetylene.

[0034] (3) The metal carbide according to (1) above, which is used to produce calcium carbonate.

[0035] (4) The metal carbide according to any one of (1) to (3) above, wherein the metal carbide reacts with pure water to generate acetylene, and the content of sulfur atoms in the metal carbide is 100 ppm or less.

[0036] (5) The metal carbide according to any one of (1) to (4) above, wherein the metal carbide reacts with pure water to generate acetylene, and the content of phosphorus atoms in the metal carbide is 1 ppm or more and 320 ppm or less.

[0037] (6) The metal carbide according to any one of (1) to (5) above, wherein the metal carbide reacts with pure water to generate acetylene, and the ash content in the metal carbide is 10 mass % or less.

[0038] (7) A method for producing a metal carbide, comprising the steps of: preparing a carbon source containing biomass and a metal source; and heating the carbon source and the metal source in an electric furnace to obtain the metal carbide according to any one of (1) to (6) above.

[0039] (8) The method for producing metal carbide according to (7) above, wherein the content of phosphorus atoms in the carbon source is 200 ppm or less.

[0040] (9) The method for producing metal carbide according to (8) above, wherein the content of the phosphorus atoms in the carbon source is 0.1 ppm or more.

[0041] (10) The method for producing metal carbide according to any one of (7) to (9) above, wherein the ash content in the carbon source is 13 mass % or less.

[0042] (11) The method for producing metal carbide according to any one of (7) to (10) above, wherein the content of sulfur atoms in the carbon source is 0.1 mass % or less.

[0043] (12) The method for producing metal carbide according to any one of (7) to (11) above, wherein the carbon source has a volatile content of 5 mass% or less as measured in accordance with JIS M 8812:2006.

[0044] (13) The method for producing metal carbide according to any one of (7) to (12) above, wherein the content of fixed carbon in the carbon source is 85 mass % or more.

[0045] (14) The method for producing metal carbide according to any one of (7) to (13) above, wherein the biomass contains at least one of charcoal, pulp carbonized material, lignin carbonized material, coconut shell carbonized material, bagasse carbonized material, and sorghum carbonized material.

[0046] (15) In the method for producing metal carbide according to any one of (7) to (14), a sample cut out from the carbon source to a size of 35 mm x 35 mm x 10 mm has a crushing strength of 30 kgf or more as measured in accordance with JIS Z 8841:1993.

[0047] (16) The method for producing metal carbide according to any one of (7) to (15) above, wherein the metal source contains an oxide of an alkaline earth metal.

[0048] (17) The method for producing metal carbide according to any one of (7) to (16) above, further comprising a step of recovering a gas produced in the electric furnace and containing at least carbon monoxide and hydrogen.

[0049] (18) The method for producing metal carbide according to (17) above, further comprising a step of reacting at least the carbon monoxide with the hydrogen to obtain a carbon compound.

[0050] (19) In the method for producing metal carbide according to any one of (7) to (18), the biomass is pulverized and sized using a pulverizer to obtain pulverized biomass, the pulverized biomass and a binder are mixed using a mixer, and then molded using a molding machine to obtain briquettes, and the briquettes are used as the carbon source.

[0051] (20) In the method for producing metal carbide according to any one of (7) to (18) above, lignocellulosic biomass is prepared as the biomass, a lignin-containing component is separated and recovered from the lignocellulosic biomass, the lignin-containing component is carbonized to obtain a lignin-containing component carbonized product, and the lignin-containing component carbonized product is used as the carbon source. Of course, the method is not limited to this.

[0052] Finally, while various embodiments of the present disclosure have been described, they are presented as examples and are not intended to limit the scope of the invention. The novel embodiments may be embodied in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. Such embodiments and modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the inventions and their equivalents as defined in the claims.

[0053] Hereinafter, metal carbide and a method for producing metal carbide will be described in more detail using the following examples and comparative examples, but these are not limited to the following examples.

[0054] 1. Preparation of raw materials <Carbon source> ・White charcoal: "Kishu Binchotan" manufactured by South Sky Co., Ltd. ・Nara black charcoal: "Black charcoal" manufactured by Yachi Forestry Co., Ltd. ・Sawmill charcoal: "Oga Binchotan" manufactured by Pearl Metal Co., Ltd. ・Coconut shell: "PKS (Palm Kernel Shell)" manufactured by Enelabo Japan Co., Ltd. ・Bagasse: "Dried Bagasse" manufactured by Bagasse Garden Co., Ltd. ・Anthracite: Hong Gay charcoal from Vietnam ・Wood chips: "Natural Season Blend Smoking Chips Value Pack" manufactured by Komeri Co., Ltd. The above white charcoal, Nara black charcoal, sawmill charcoal, and anthracite were each crushed and sieved to an average particle size of approximately 10 mm before use. <Calcium source (metal source)> ・Calcium oxide: Calcium oxide, 99.9%, manufactured by Fujifilm Wako Pure Chemical Corporation <Barium source (metal source)> ・Barium carbonate: Barium carbonate, 99.9%, manufactured by Fujifilm Wako Pure Chemical Corporation

[0055] 2. Production of Metal Carbide (Example 1) First, 111 parts by mass of white charcoal as a carbon source and 155 parts by mass of calcium oxide as a calcium source were mixed to obtain a mixture so that the amount of fixed carbon charged was 100 parts by mass. Next, this mixture was placed in a multipurpose high-temperature furnace (manufactured by Fuji Denpa Kogyo Co., Ltd., "Hi-Multi Series") and heated at 2000°C for 1 hour while flowing argon at a rate of 7 L / hr. This produced calcium carbide.

[0056] Example 2: Calcium carbide was obtained in the same manner as in Example 1, except that 133 parts by mass of sawdust charcoal was used as the carbon source. Example 3: Calcium carbide was obtained in the same manner as in Example 1, except that 111 parts by mass of sawdust charcoal was used as the carbon source.

[0057] Example 4: Calcium carbide was obtained in the same manner as in Example 1, except that 56 parts by mass of white charcoal and 59 parts by mass of anthracite were used as the carbon source. Example 5: Calcium carbide was obtained in the same manner as in Example 1, except that 11 parts by mass of white charcoal and 106 parts by mass of anthracite were used as the carbon source.

[0058] Example 6 Calcium carbide was obtained in the same manner as in Example 1, except that 1 part by mass of white charcoal and 116 parts by mass of anthracite were used as the carbon source.

[0059] Example 7 Coconut shells were placed in a multipurpose high-temperature furnace (Fuji Denpa Kogyo Co., Ltd., "High Multi Series") and heated at 800°C while flowing argon at a rate of 7 L / hr until the fixed carbon reached 90% by mass, yielding coconut shell carbide. Next, 111 parts by mass of coconut shell carbide was mixed with 195 parts by mass of calcium oxide as a calcium source to obtain a mixture. This mixture was then placed in a multipurpose high-temperature furnace and heated at 2000°C for 1 hour while flowing argon at a rate of 7 L / hr. This yielded calcium carbide.

[0060] Example 8 Bagasse was placed in a multipurpose high-temperature furnace (Fuji Denpa Kogyo Co., Ltd., "High Multi Series") and heated at 800°C while flowing argon at a rate of 7 L / hr until the fixed carbon content reached 90% by mass, yielding bagasse charcoal. Next, 111 parts by mass of the bagasse charcoal and 195 parts by mass of calcium oxide as a calcium source were mixed to obtain a mixture. This mixture was then placed in a multipurpose high-temperature furnace and heated at 2000°C for 1 hour while flowing argon at a rate of 7 L / hr. This yielded calcium carbide.

[0061] Example 9: The bagasse charcoal obtained in Example 8 was pulverized using a disk mill to obtain bagasse charcoal powder (pulverized bagasse charcoal) with an average particle size of 350 μm. Next, 100 parts by mass of the bagasse charcoal powder and 8 parts by mass of asphalt binder were mixed in a batch mixer until the moisture content reached 7% by mass. This mixture was then molded at a linear pressure of 10 kN / cm using a double-roll molding machine with recesses measuring 34.8 mm x 30 mm x 9.4 mm to obtain bagasse charcoal briquettes. After measuring the crushing strength, 114 parts by mass of the bagasse charcoal briquettes were mixed with 195 parts by mass of calcium oxide as a calcium source to obtain a mixture. This mixture was then placed in a multipurpose high-temperature furnace and heated at 2000 °C for 1 hour while flowing argon at a rate of 7 L / hr. This produced calcium carbide.

[0062] (Example 10) Wood chips were hydrolyzed using a concentrated sulfuric acid method, and then the residue was collected by filtration. The resulting residue was washed with hot water at 80°C, followed by acetone, ethyl acetate, and toluene to obtain wood chip-derived lignin. The obtained wood chip-derived lignin was then placed in a multipurpose high-temperature furnace (Fuji Denpa Kogyo Co., Ltd., "High Multi Series") and heated at 800°C while flowing argon at a rate of 7 L / hr until the fixed carbon reached 90% by mass, thereby obtaining wood chip-derived lignin carbonized material. Next, 111 parts by mass of the wood chip-derived lignin carbonized material and 195 parts by mass of calcium oxide as a calcium source were mixed to obtain a mixture. Next, this mixture was placed in a multipurpose high-temperature furnace and heated at 2000°C for 1 hour while flowing argon at a rate of 7 L / hr. This resulted in calcium carbide.

[0063] Example 11 The wood chip-derived lignin obtained in Example 10 was heated at 300°C to obtain wood chip-derived lignin hemicarbonized. 100 parts by mass of the wood chip-derived lignin hemicarbonized and 8 parts by mass of asphalt binder were mixed using a batch mixer to obtain wood chip-derived lignin hemicarbonized pellets. The wood chip-derived lignin hemicarbonized pellets were then placed in a multipurpose high-temperature furnace (Fuji Denpa Kogyo Co., Ltd., "High Multi Series"), and heated at 800°C under a reduced pressure of 10 Pa at 20 MPa using a press until the fixed carbon reached 90%, thereby obtaining wood chip-derived lignin molded charcoal. Next, 111 parts by mass of the wood chip-derived lignin molded charcoal and 195 parts by mass of calcium oxide as a calcium source were mixed to obtain a mixture. This mixture was then placed in a multipurpose high-temperature furnace and heated at 2000°C for 1 hour while flowing argon at a rate of 7 L / hr. This resulted in calcium carbide.

[0064] Example 12 A mixture was obtained by mixing 111 parts by mass of the wood chip-derived lignin carbonized material obtained in Example 10 with 411 parts by mass of barium carbonate as a barium source. Next, this mixture was placed in a multipurpose high-temperature furnace and heated at 1550°C for 1 hour while flowing argon at a rate of 7 L / hr. As a result, barium carbide was obtained.

[0065] Comparative Example Calcium carbide was obtained in the same manner as in Example 1, except that 118 parts by mass of anthracite was used as the carbon source.

[0066] 3. Measurement 3-1. Measurement of biomass degree The biomass carbon source used in each example and comparative example and the metal carbide obtained in each example and comparative example were measured by accelerator mass spectrometry (AMS) in accordance with ASTM D6866, and the biomass degree was calculated according to the following formula: Biomass degree (%) = Biomass carbon source or metal carbide １４ Mass of C / mass of total carbon atoms in biomass carbon source or metal carbide × 100

[0067] 3-2. Measurement of phosphorus atom and sulfur atom contents in biomass carbon source and anthracite The phosphorus atom and sulfur atom contents (phosphorus content and sulfur content) in the biomass carbon source and anthracite were measured in accordance with JIS M 8813:2004. 3-3. Measurement of carbon atom (fixed carbon) content in biomass carbon source and anthracite The carbon atom content (fixed carbon content) in the biomass carbon source and anthracite was measured in accordance with JIS M 8812:2006.

[0068] 3-4. Measurement of ash content in biomass carbon source The ash content in the biomass carbon source (ash content) was measured in accordance with JIS M 8812:2006. 3-5. Measurement of crushing strength of biomass carbon source The biomass carbon source was molded into a sample measuring 35 mm x 35 mm x 10 mm. The crushing strength of this sample was measured in accordance with JIS Z 8841:1993.

[0069] 3-6. Measurement of phosphorus atom content in metal carbide Acetylene gas was generated from metal carbide in accordance with JIS K 1901:2003. The phosphine content in the acetylene gas (phosphine content) was measured in accordance with JIS K 1901:2003. The phosphorus atom content in the metal carbide (phosphorus content) was calculated from the phosphine content in the acetylene as follows. [wherein Cp is the phosphorus content in the metal carbide, Ap is the phosphine content in the acetylene gas, and Mc is the formula weight of the metal carbide.]

[0070] 3-7. Measurement of sulfur atom content in metal carbide Acetylene gas was generated from metal carbide in accordance with JIS K 1901:2003. The hydrogen sulfide content in the acetylene gas (hydrogen sulfide content) was measured in accordance with JIS K 1901:2003. The sulfur atom content in the metal carbide (sulfur content) was calculated from the hydrogen sulfide content in the acetylene as follows. [wherein Cs is the phosphorus content in the metal carbide, As is the phosphine content in the acetylene gas, and Mc is the formula weight of the metal carbide.]

[0071] 3-8. Measurement of Ash Content in Metal Carbide Calcium hydroxide was obtained by reacting 100 parts by mass of calcium carbide from Examples 1 to 11 and the Comparative Example with 58 parts by mass of pure water. The resulting calcium hydroxide was dried at 150°C until the water content was 0.1% by mass or less. The purity of the calcium hydroxide was measured in accordance with JIS K 8575:2025. Barium hydroxide was obtained by reacting 100 parts by mass of barium carbide from Example 12 with 30 parts by mass of pure water. The resulting barium hydroxide was dried at 150°C until the water content was 0.1% by mass or less. The purity of the barium hydroxide was measured in accordance with JIS K 1417-1992. The ash content in the metal carbide was calculated from the purity of calcium hydroxide or barium hydroxide measured as described above as follows. [where Mc is the formula weight of the metal carbide, Ac is the ash content of the metal carbide, M ＯＨ : Formula weight of metal hydroxide, P ＯＨ : Purity of metal hydroxide.]

[0072] The results are shown in Tables 1 and 2 below.

[0073]

[0074] As shown in Tables 1 and 2, it was confirmed that metal carbides having a biomass content according to the mass balance can be produced.

Claims

1. Metal carbide as specified in ASTM D6866 １４ A metal carbide having a biomass ratio of 0.01% or more and 100% or less as measured by a C isotope measurement method.

2. The metal carbide according to claim 1, which is used to produce acetylene.

3. The metal carbide according to claim 1, which is used to produce calcium carbonate.

4. The metal carbide according to claim 1, wherein said metal carbide reacts with pure water to generate acetylene, and the content of sulfur atoms in said metal carbide is 100 ppm or less.

5. The metal carbide according to claim 1, wherein said metal carbide reacts with pure water to generate acetylene, and the content of phosphorus atoms in said metal carbide is 1 ppm or more and 320 ppm or less.

6. The metal carbide according to claim 1, wherein the metal carbide reacts with pure water to generate acetylene, and the ash content in the metal carbide is 10 mass % or less.

7. A method for producing metal carbide, comprising the steps of: preparing a carbon source containing biomass and a metal source; and heating the carbon source and the metal source in an electric furnace to obtain the metal carbide according to any one of claims 1 to 6.

8. The method for producing metal carbide according to claim 7, wherein the content of phosphorus atoms in the carbon source is 200 ppm or less.

9. The method for producing metal carbide according to claim 8, wherein the content of the phosphorus atoms in the carbon source is 0.1 ppm or more.

10. The method for producing metal carbide according to claim 7, wherein the ash content in the carbon source is 13 mass % or less.

11. The method for producing metal carbide according to claim 7, wherein the content of sulfur atoms in the carbon source is 0.1 mass % or less.

12. The method for producing metal carbide according to claim 7, wherein the carbon source has a volatile content of 5 mass % or less as measured in accordance with JIS M 8812:2006.

13. The method for producing metal carbide according to claim 7, wherein the content of fixed carbon in the carbon source is 85 mass % or more.

14. The method for producing metal carbide according to claim 7, wherein the biomass contains at least one of charcoal, pulp carbonized material, lignin carbonized material, coconut shell carbonized material, bagasse carbonized material, and sorghum carbonized material.

15. The method for producing metal carbide according to claim 7, wherein a sample cut from the carbon source to a size of 35 mm x 35 mm x 10 mm has a crushing strength of 30 kgf or more as measured in accordance with JIS Z 8841:1993.

16. The method for producing metal carbide according to claim 7, wherein the metal source comprises an oxide of an alkaline earth metal.

17. The method for producing metal carbide according to claim 7, further comprising the step of recovering gas produced in the electric furnace and containing at least carbon monoxide and hydrogen.

18. The method for producing metal carbide according to claim 17, further comprising the step of reacting at least the carbon monoxide with the hydrogen to obtain a carbon compound.

19. A method for producing metal carbide according to claim 7, wherein the biomass is pulverized and sized using a pulverizer to obtain pulverized biomass, the pulverized biomass and a binder are mixed using a mixer, and then molded using a molding machine to obtain briquettes, and the briquettes are used as the carbon source.

20. A method for producing metal carbide as described in claim 7, comprising: preparing lignocellulosic biomass as the biomass; separating and recovering lignin-containing components from the lignocellulosic biomass; carbonizing the lignin-containing components to obtain lignin-containing component chars; and using the lignin-containing component chars as the carbon source.

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