A method for preparing calcium carbide using by-product carbon from acetylene production through thermal cracking of methane

Abstract

The present invention discloses a method for preparing calcium carbide using byproduct carbon from the thermal cracking of methane to produce acetylene. The method comprises: mixing the byproduct carbon from the thermal cracking of methane to produce acetylene, a calcium source, and a catalytic binder, pressing and forming the mixture, drying the mixture, and then heating the mixture under an inert atmosphere to produce calcium carbide. The binder comprises at least one of potassium humate, sodium humate, calcium humate, magnesium humate, calcium carboxymethyl cellulose, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, sodium lignin sulfonate, potassium lignin sulfonate, magnesium lignin sulfonate, and calcium lignin sulfonate. The present invention bonds the nanoscale byproduct carbon with the catalytic binder. The metal ions in the binder catalyze the reaction, promoting the production of calcium carbide, thereby repurposing the byproduct carbon as a resource.

Description

Technical Field

[0001] The present invention relates to the technical field of by-product carbon treatment, and in particular to a method for preparing calcium carbide by utilizing by-product carbon produced by thermal cracking of methane to produce acetylene. Background Art

[0002] Acetylene (C2H2) is a key raw material for the chemical industry. Thermal cracking of methane is one of the primary routes for its industrial production, but this process produces a significant amount of byproduct carbon. Currently, the industry typically disposes of this byproduct by incineration, a method that typically requires expensive combustion equipment and can also cause secondary carbon dust pollution.

[0003] The resource utilization of by-product carbon is a highly promising development direction. By-product carbon has the following characteristics: a complex composition, containing various carbon structures such as amorphous carbon and graphitic carbon, and the presence of organic matter on its surface, such as polycyclic aromatic hydrocarbons; and a powdery, fine particle size, reaching the nanometer scale. These characteristics make its removal difficult and uneconomical. The development of efficient and clean conversion technologies for by-product carbon requires full consideration of these characteristics.

[0004] Calcium carbide (primarily calcium carbide, CaC2) is a key product in the coal chemical industry and a key raw material for acetylene production and downstream derivative synthesis. Calcium carbide is primarily produced using the electric arc method. The traditional process involves adding a mixture of lump coke (5-30 mm) and calcium oxide (5-30 mm) to an electric furnace. The mixture reacts under high temperatures (above 2000°C) generated by the electric arc. The generated CO gas is discharged from the upper furnace, while the molten CaC2 is discharged from the furnace bottom. The product is then cooled and crushed to obtain the finished product.

[0005] The new electric arc method involves reacting pulverized coal with a calcium-based material at high temperature in an electric arc furnace. For example, patent specification CN106241810A discloses a method for producing calcium carbide, comprising the following steps: A. pyrolyzing coal in a pyrolysis furnace to produce pyrolytic carbon at a temperature of T1, which is then discharged from the pyrolytic carbon outlet of the pyrolysis furnace; B. feeding the pyrolytic carbon into a kneading and briquetting device through the raw material inlet of the kneading and briquetting device, and also feeding quicklime at a temperature of T2 and a binder at a temperature of T3 into the kneading and briquetting device; within the kneading and briquetting device, the pyrolytic carbon, quicklime, and binder are uniformly mixed, kneaded, and briquette into pellets, which are then discharged through the pellet outlet of the kneading and briquetting device; and C. feeding the pellets into a calcium carbide furnace through the pellet inlet of the calcium carbide furnace, where calcium carbide production occurs. The binder used in this patented technology is one or more of coal tar, asphaltene, anthracene oil, tire powder, rubber powder, plastic particles, phosphoric acid, phosphates, phenolic resin, and epoxy resin. However, pulverized coal contains a large amount of ash, and the inorganic substances in the ash produce carbide slag, which is difficult to recycle, thereby generating a large amount of solid waste and increasing the environmental burden.

[0006] Patent specification CN103708458A discloses a method for preparing calcium carbide, comprising: pyrolyzing waste tires to produce high-temperature oil and gas, iron wire, and nano-sized tire carbon black; mixing the nano-sized tire carbon black with a calcium-based raw material to obtain a mixture; shaping the mixture to obtain a bulk feedstock; and smelting the bulk feedstock in an electric arc furnace to obtain calcium carbide, wherein the smelting is performed at 1400-1750 degrees Celsius for 5-45 minutes. The resulting calcium carbide product has a gas emission of up to 290 L / kg. This patented technology uses nano-sized tire carbon black, whose composition and characteristics differ significantly from the by-product carbon produced by the present invention.

[0007] At present, there is no mature technology for efficiently preparing high-quality calcium carbide using the by-product carbon from the thermal cracking of methane to produce acetylene. The main reason is that the by-product carbon has a high degree of graphitization, which makes the material highly inert to reaction. Summary of the Invention

[0008] In response to the above-mentioned technical problems and the shortcomings in the field, the present invention provides a method for preparing calcium carbide using by-product carbon from the thermal cracking of methane to produce acetylene. By adding a catalytic binder, nano-scale by-product carbon is mixed with a calcium source and then pressed into shape. At the same time, the metal ions (potassium, sodium, calcium, magnesium) in the binder can play a catalytic role, promoting the conversion of by-product carbon into calcium carbide, breaking through the reaction inertness barrier of the by-product carbon, and realizing the preparation of calcium carbide from the by-product carbon. This can not only solve the problem of solid waste disposal of by-product carbon from the thermal cracking of methane to produce acetylene, but also generate high-value-added calcium carbide. In addition, the calcium carbide slag produced by the hydrolysis of the obtained calcium carbide to produce acetylene is ash-free and can be recycled and used again to produce acetylene together with the by-product carbon, forming a complete closed loop of resource utilization.

[0009] The specific technical solutions are as follows:

[0010] See also Figure 1 A method for preparing calcium carbide using by-product carbon from the thermal cracking of methane to produce acetylene, comprising: mixing the by-product carbon from the thermal cracking of methane to produce acetylene, a calcium source, and a catalytic binder, pressing and forming the mixture, drying the mixture, and then heating the mixture under an inert atmosphere to obtain calcium carbide;

[0011] The binder includes at least one of potassium humate, sodium humate, calcium humate, magnesium humate, calcium carboxymethyl cellulose, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, sodium lignin sulfonate, potassium lignin sulfonate, magnesium lignin sulfonate, and calcium lignin sulfonate, and preferably includes at least one of calcium humate, calcium carboxymethyl cellulose, and calcium lignin sulfonate. The preferred binder can make the obtained calcium carbide have a higher gas generation rate and the reaction conditions such as the temperature required for preparing calcium carbide more mild.

[0012] The by-product carbon from the thermal cracking of methane to produce acetylene is different from other carbon sources. Its main component is carbon black, and it also contains a small amount of amorphous carbon and organic carbon species adsorbed on the surface (such as carbon deposit compounds such as polycyclic aromatic hydrocarbons). The particle size is nanometer-scale and it contains almost no ash. In theory, it can avoid the problem of carbide slag impurities and improve recycling efficiency.

[0013] The by-product carbon from the thermal cracking of methane to produce acetylene is considered by the industry to be a waste that cannot be directly used for calcium carbide synthesis due to its complex composition and high degree of graphitization. The present invention achieves efficient conversion of the by-product carbon into calcium carbide through the coordinated design of a specific binder system and process technology, and constructs a closed-loop circulation system, solving the problem of incompatibility between the physical properties of the by-product carbon and the calcium carbide production process. The present invention converts the by-product carbon from the thermal cracking of methane to produce acetylene into calcium carbide, which not only solves the problem of solid waste disposal of the by-product carbon, but also generates high-value-added calcium carbide, achieving efficient resource utilization.

[0014] The binder used in this invention is not a single binding medium; its unique feature lies in the synergistic effect of the organic carrier and metal ions. The metal ions (K, Na, Mg, and Ca) in the binder are pre-dispersed by the organic carrier to form nano-active sites. Furthermore, potassium humate, sodium humate, calcium humate, magnesium humate, calcium carboxymethyl cellulose, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, sodium lignin sulfonate, potassium lignin sulfonate, magnesium lignin sulfonate, and calcium lignin sulfonate have low melting points, and the liquid phase formed upon melting facilitates improved raw material contact. Humic acid contains carboxyl and phenolic hydroxyl groups, carboxymethyl cellulose contains carboxymethyl groups, and lignin sulfonic acid contains sulfonic acid groups. These functional groups, through chelation or ion exchange, secure the metal ions (K, Na, Mg, and Ca) as highly dispersed active sites, activating the by-product carbon, thereby promoting the reaction of the highly graphitized by-product carbon with a calcium source to form calcium carbide. This overcomes the reaction inertness barrier of methane cracking by-product carbon due to its high degree of graphitization, enabling resource utilization of the by-product carbon.

[0015] In some embodiments, in the method of preparing calcium carbide using by-product carbon from the thermal cracking of methane to produce acetylene, the calcium source may include one or a mixture of calcium carbonate, calcium oxide, calcium hydroxide, cyanamide waste residue, and calcium carbide slag.

[0016] In some embodiments, in the method of preparing calcium carbide using by-product carbon from the thermal cracking of methane to produce acetylene, based on the total mass of the calcium source and the by-product carbon from the thermal cracking of methane to produce acetylene as 100%, the mass proportion of the binder can be 1% to 20%, for example, 5%, 10%, 15%, etc.

[0017] The present invention makes adaptive adjustments to the ratio of by-product carbon and calcium source based on the special selection and dosage limitation of the binder.

[0018] In some embodiments, in the method of preparing calcium carbide using by-product carbon from the thermal cracking of methane to produce acetylene, the mass ratio of the calcium source to the by-product carbon from the thermal cracking of methane to produce acetylene can be 2~5:1, for example 3:1, 4:1, etc.

[0019] In the present invention, the inert atmosphere refers to an atmosphere that does not participate in the reaction, such as one or more combinations of nitrogen (N2) atmosphere, argon and other rare gas atmospheres, etc.

[0020] The method of the present invention utilizes a catalytic binder, significantly reducing the temperature required for the heating reaction between the byproduct carbon and a calcium source to produce calcium carbide. In some embodiments, the method of preparing calcium carbide using the byproduct carbon from the thermal cracking of methane to produce acetylene can be performed at a heating temperature of 1000-1800°C, for example, 1500°C.

[0021] In some embodiments, in the method for preparing calcium carbide using the by-product carbon from the thermal cracking of methane to produce acetylene, the heating time can be 30 to 90 minutes, for example, 60 minutes.

[0022] The method for preparing calcium carbide using the by-product carbon from the thermal cracking of methane to produce acetylene, wherein the gas emission of the calcium carbide is not less than 260 L / kg, further not less than 270 L / kg, and exemplarily between 270 and 295 L / kg.

[0023] The method for preparing calcium carbide using by-product carbon from the thermal cracking of methane to produce acetylene is described. The calcium carbide is ash-free, and the carbide slag obtained by hydrolyzing the carbide to produce acetylene has calcium hydroxide as the main component, which also does not contain ash and can be directly recycled as a calcium source. In some embodiments, the method for preparing calcium carbide using by-product carbon from the thermal cracking of methane to produce acetylene also includes a carbide slag recycling process. The carbide slag recycling process includes: using the carbide slag produced after the calcium carbide is hydrolyzed to obtain acetylene gas as part or all of the calcium source, mixing it with the by-product carbon from the thermal cracking of methane to produce acetylene and a catalytic binder, pressing and molding, drying, and then heating in an inert atmosphere to obtain calcium carbide.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention proposes a method for preparing calcium carbide using by-product carbon from the thermal cracking of methane to produce acetylene. After the methane cracking by-product carbon is mixed with a calcium source through a catalytic binder, the activity of the mixed raw materials is increased, breaking through the reaction inertness barrier caused by the high degree of graphitization of the methane cracking by-product carbon. The by-product carbon and calcium sources such as calcium carbonate are converted into high-value-added calcium carbide. In addition, the carbide slag produced by the hydrolysis of the obtained calcium carbide to produce acetylene is ash-free and can be recycled and used again to produce acetylene together with the by-product carbon, forming a complete closed loop of resource utilization. The method of the present invention solves the problem of solid waste disposal of the by-product carbon and realizes the resource utilization of the by-product carbon. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the method for preparing calcium carbide using the by-product carbon produced by thermal cracking of methane to produce acetylene.

[0027] Figure 2 1 is a relationship diagram between the gas evolution of the calcium carbide obtained in Examples 1 to 4 and the binder humate. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings and specific examples. It should be understood that these examples are intended to illustrate the present invention and are not intended to limit the scope of the invention. The operating methods in the following examples where no specific conditions are specified are generally performed under conventional conditions or as recommended by the manufacturer.

[0029] In the following examples, an appropriate amount of calcium carbide product is added with water to measure the volume of acetylene gas and calculate the carbide gas production. Calcium carbide gas production is defined as the volume of acetylene gas generated per unit mass of calcium carbide when it reacts with water. It is a key indicator of calcium carbide quality and production efficiency.

[0030] Example 1:

[0031] Using cyanamide waste residue as a calcium source, the calcium source and by-product carbon powder are mixed with a binder calcium humate at a mass ratio of 4:1. The amount of the binder accounts for 5wt% of the sum of the amount of the calcium source and the by-product carbon to prepare a mixed raw material. The mixed raw material is pressed into shape and then dried to obtain a sample raw material. The sample is placed in a reaction chamber, N2 is introduced into the reaction chamber and heated to 1500°C for 60 min to obtain a calcium carbide product. The product is tested for gas emission and its gas emission volume reaches 295 L / kg. Figure 2 shown.

[0032] Example 2:

[0033] Using cyanamide waste residue as a calcium source, the calcium source and by-product carbon powder are mixed with a binder potassium humate at a mass ratio of 4:1. The amount of the binder accounts for 5wt% of the sum of the amount of the calcium source and the by-product carbon to prepare a mixed raw material. The mixed raw material is pressed into shape and then dried to obtain a sample raw material. The sample is placed in a reaction chamber, N2 is introduced into the reaction chamber and heated to 1500°C for 60 min to obtain a calcium carbide product. The product is tested for gas emission and its gas emission volume reaches 285 L / kg. Figure 2 shown.

[0034] Example 3:

[0035] Using cyanamide waste residue as a calcium source, the calcium source and by-product carbon powder are mixed with a binder sodium humate at a mass ratio of 4:1. The amount of the binder accounts for 5wt% of the sum of the amount of the calcium source and the by-product carbon to prepare a mixed raw material. The mixed raw material is pressed into shape and then dried to obtain a sample raw material. The sample is placed in a reaction chamber, N2 is introduced into the reaction chamber and heated to 1500°C for 60 min to obtain a calcium carbide product. The product is tested for gas emission and its gas emission volume reaches 279 L / kg. Figure 2 shown.

[0036] Example 4:

[0037] Using cyanamide waste residue as a calcium source, the calcium source and by-product carbon powder are mixed with a binder magnesium humate at a mass ratio of 4:1. The amount of the binder accounts for 5wt% of the sum of the amount of the calcium source and the by-product carbon to prepare a mixed raw material. The mixed raw material is pressed into shape and then dried to obtain a sample raw material. The sample is placed in a reaction chamber, N2 is introduced into the reaction chamber and heated to 1500°C for 60 min to obtain a calcium carbide product. The product is tested for gas emission and its gas emission volume reaches 271 L / kg. Figure 2 shown.

[0038] Example 5:

[0039] Calcium carbonate was used as a calcium source. The calcium source and by-product carbon powder were mixed in a 4:1 mass ratio with sodium lignin sulfonate as a binder. The binder amount accounted for 5 wt% of the total amount of calcium source and by-product carbon. The mixed raw material was pressed into shape and then dried to obtain a sample. The sample was placed in a reaction chamber, which was then heated to 1500°C for 60 minutes under nitrogen. This produced a calcium carbide product. Gas generation testing revealed a gas emission of 283 L / kg.

[0040] Example 6:

[0041] Cyanamide waste residue was used as a calcium source. The calcium source and by-product carbon powder were mixed with potassium lignin sulfonate as a binder at mass ratios of 2:1, 3:1, 4:1, and 5:1, respectively. The binder amount accounted for 5 wt% of the total amount of calcium source and by-product carbon. Each mixed raw material was pressed into shape and then dried to obtain the sample raw materials. Each sample was placed in a reaction chamber and heated to 1500°C under a nitrogen atmosphere for 60 minutes to synthesize the calcium carbide product.

[0042] After all the carbide products obtained above are hydrolyzed to release acetylene gas, the resulting by-product carbide slag slurry is collected, filtered, and dried to obtain dry carbide slag. This ash-free carbide slag, primarily composed of calcium hydroxide, can be directly used as a calcium source for carbide production, achieving recycling. The carbide slag used as the calcium source is mixed with by-product carbon powder in a 4:1 mass ratio using potassium lignin sulfonate as a binder, with the binder amount accounting for 5 wt% of the combined calcium source and by-product carbon to prepare a mixed raw material. The mixed raw material is pressed into shape and then dried to obtain a sample raw material. The sample is placed in a reaction chamber, which is then purged with nitrogen and heated to 1500°C for 60 minutes to obtain a carbide product. Gas generation testing of the product reveals a gas emission of 271 L / kg.

[0043] The calcium carbide products prepared by the method of the present invention all meet the requirements of the national standard (GB10665-2004) for qualified calcium carbide products (gas generation volume ≥ 260 L / kg).

[0044] In summary, the by-product carbon from the thermal cracking of methane to produce acetylene is nano-dispersed and has a high degree of graphitization, so it cannot be converted into calcium carbide using existing calcium carbide synthesis methods and equipment. Through the method of the present invention, the nano-scale by-product carbon is bonded together by a catalytic binder. The metal ions in the binder can catalyze the reaction and promote the formation of calcium carbide, thereby solving the problem of resource utilization of the by-product carbon.

[0045] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for preparing calcium carbide using carbon produced as a by-product of acetylene production from methane thermal cracking, characterized in that: include: By-product carbon from the thermal cracking of methane to produce acetylene, a calcium source, and a catalytic binder are mixed, pressed into shape, dried, and then heated under an inert atmosphere to obtain calcium carbide; the mass ratio of the calcium source to the by-product carbon from the thermal cracking of methane to produce acetylene is 2-5:1; and the mass proportion of the binder is 1%-20% based on the total mass of the calcium source and the by-product carbon from the thermal cracking of methane to produce acetylene being 100%; The binder is at least one of calcium humate, calcium carboxymethyl cellulose, and calcium lignin sulfonate.

2. The method according to claim 1, characterized in that The calcium source includes one or a mixture of calcium carbonate, calcium oxide, calcium hydroxide, cyanamide waste residue, and carbide slag.

3. The method according to claim 1, characterized in that The inert atmosphere is one or more combinations of nitrogen and argon.

4. The method according to claim 1, wherein The heating temperature is 1000-1800°C.

5. The method according to claim 1, wherein The heating time is 30 to 90 minutes.

6. The method according to claim 1, characterized in that The calcium carbide is ash-free and has a gas generation capacity of 270-295 L / kg.

7. The method according to claim 1 or 6, characterized in that The method also includes a carbide slag recycling process, which includes: using the carbide slag produced after hydrolyzing the carbide to obtain acetylene gas as part or all of the calcium source, mixing it with the by-product carbon produced by thermal cracking of methane to produce acetylene and a catalytic binder, pressing and molding, drying, and then heating in an inert atmosphere to obtain calcium carbide.

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