A method for producing hydrogen by methane cracking
By using Fe-Al catalysts prepared from red mud, the problems of deactivation and carbon dioxide emissions of iron-based catalysts have been solved, achieving efficient methane cracking for hydrogen production and the generation of high-value-added carbon by-products, thus achieving the effects of environmentally friendly and efficient hydrogen production and solid waste resource utilization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN INSTITUTE OF CHEMICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2024-12-04
- Publication Date
- 2026-06-05
AI Technical Summary
Existing iron-based catalysts are prone to deactivation during methane cracking for hydrogen production, exhibiting insufficient catalytic activity and stability, and traditional hydrogen production methods also suffer from carbon dioxide emissions.
A Fe-Al composite catalyst derived from red mud was used to prepare a catalyst through specific pretreatment and modification activation steps. The catalyst was used for methane cracking reaction to generate hydrogen and solid carbon byproducts. The reaction conditions were optimized to be 600–1000 °C, 0.1–0.5 MPa and space velocity of 3000–15000 ml·g⁻¹·h⁻¹.
It achieves a high methane conversion rate of over 90%, with no carbon dioxide emissions. The generated solid carbon byproducts have high added value and can be used for energy storage and conductive materials, realizing environmentally friendly and efficient hydrogen production and the value utilization of industrial solid waste resources.
Smart Images
Figure CN122144660A_ABST
Abstract
Description
Technical Field
[0001] This application relates to a method for producing hydrogen from methane through cracking, which belongs to the field of chemical engineering. Background Technology
[0002] Hydrogen, as a clean energy source and industrial feedstock, is in ever-increasing demand. Traditional hydrogen production methods, such as steam reforming, often involve significant carbon dioxide emissions, posing a substantial carbon pollution problem. Methane pyrolysis, a carbon dioxide-free hydrogen production method, decomposes methane (CH₂) into hydrogen and solid carbon, avoiding carbon dioxide generation. Current research indicates that using metal catalysts can significantly improve the reaction efficiency of methane pyrolysis, especially iron-based catalysts, which exhibit excellent catalytic performance. However, single iron-based catalysts are prone to deactivation during long-term use, and their catalytic activity and stability still need improvement. Therefore, developing a methane pyrolysis method using an iron-aluminum composite catalyst derived from red mud solid waste to improve catalyst activity and reduce costs, thereby realizing the valuable utilization of solid waste resources, has significant research and application value. Summary of the Invention
[0003] The purpose of this invention is to provide a method for producing hydrogen by catalytic cracking of methane using an Fe-Al composite catalyst derived from red mud solid waste. By improving the activity of the catalyst, a higher methane conversion rate can be achieved, while obtaining high-value-added solid carbon byproducts.
[0004] According to one aspect of this application, a method for producing hydrogen from methane by cracking is provided, comprising the following steps:
[0005] In the reactor, methane is contacted with a solid waste catalyst and reacted to produce hydrogen and solid carbon materials.
[0006] The solid waste catalyst is prepared using red mud as raw material.
[0007] The reaction temperature is 600–1000℃;
[0008] The space velocity of the reaction is 3000–15000 ml·g. -1 ·h -1 .
[0009] The reaction is carried out at a pressure of 0.1–0.5 MPa.
[0010] The solid waste catalyst is obtained through the following steps: including a pretreatment stage and a modification and activation stage;
[0011] The pretreatment stage includes: washing the Bayer red mud to remove surface deposits and soluble salts, and drying it with hot air or natural sun drying to obtain dried red mud; and grinding the dried red mud into red mud powder using a ball mill or other pulverizing equipment.
[0012] The modification and activation stage includes: mixing red mud powder with dilute sulfuric acid or dilute hydrochloric acid with pH = 5.5-6, and carrying out a leaching reaction at 50-70℃ to dissolve some impurities and expose the surface of active metal oxides. After filtration, the mixture is washed and filtered 5 times with deionized water until the filtrate is approximately neutral. The mixture is then allowed to stand and dry at room temperature for 24 hours, and then calcined at 700℃ for 6 hours in a calcination furnace. After high-temperature calcination, a small amount of water is added in the form of a spray, and the mixture is granulated to 40-80 mesh by rolling and sieving to obtain shaped catalyst particles. The shaped catalyst particles are then dried again in a drying oven at 110℃ to obtain the red mud-based Fe-Al catalyst, i.e., the solid waste catalyst.
[0013] Specifically, a sufficient amount of methane-rich gas is introduced into the reactor, and an Fe-Al catalyst is placed in the bed. The reactor is heated to a temperature range of 600℃ to 1000℃ to efficiently catalyze methane cracking. During this process, the maximum methane conversion rate exceeds 90%. The main product is hydrogen, and the byproduct is elemental carbon. The solid carbon byproduct can be used in battery materials, conductive materials, or other industrial applications.
[0014] The reaction equation is: CH4→C+2H2;
[0015] The reactor can be a fixed-bed reactor or a fluidized-bed reactor.
[0016] The main gaseous products of the reaction are hydrogen and a small amount of methane, which can be separated and purified to obtain high-purity hydrogen.
[0017] This invention provides a method for hydrogen production from methane via cracking using an Fe-Al catalyst derived from metallurgical solid waste. By optimizing the catalyst composition and reaction conditions, a highly efficient and environmentally friendly hydrogen production process is achieved, while simultaneously producing high-value-added solid carbon materials. The beneficial effects of this invention are as follows:
[0018] (1) High-efficiency hydrogen production: The Fe-Al composite catalyst of the present invention can achieve high-efficiency methane cracking in the temperature range of 600℃ to 1000℃, with a maximum methane conversion rate of over 90%.
[0019] (2) Environmentally friendly and low-carbon: Compared with the traditional steam reforming method for hydrogen production, the process of the present invention does not produce carbon dioxide during the hydrogen production process, and has a significant carbon emission reduction effect.
[0020] (3) Environmental friendliness of catalyst source: The main elements and proportions of the Fe-Al composite catalyst can be derived from industrial solid waste such as red mud. This realizes the value utilization of industrial solid waste.
[0021] (4) Solid carbon byproducts: The elemental carbon generated during the reaction process has good electrical conductivity and structural properties as a solid carbon material. It can be used as a high-value-added product such as energy storage and conductive materials, further improving the economic benefits of the process. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of the production process of the present invention. Detailed Implementation
[0023] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0024] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.
[0025] Preparation Example 1
[0026] Take 50g of Bayer red mud, wash and filter it in deionized water, and dry it in an oven at 110℃ for 6 hours to remove moisture. Grind the dried red mud in a ball mill for 30 minutes, then pass it through a 100-mesh sieve to collect the fine powder. Place the red mud powder in a 500mL beaker, add 250mL of hydrochloric acid solution with a pH of 5–5.5, and stir magnetically for 60 minutes to remove calcium and other soluble impurities. After the reaction, filter with filter paper. Wash the solid repeatedly with deionized water until the filtrate is nearly neutral (pH 6.5–7.0), obtaining approximately 40g of filter residue. After static drying, calcine the residue in a calcination furnace at a temperature increased to 700℃ at 5℃ / min and held for 6 hours. Allow the calcined product to cool naturally to room temperature. Prepare microspheres with a diameter of approximately 1–2mm using a spray-drying method. Further dry the particles in an oven at 80℃ for 12 hours to obtain the final Fe-Al catalyst.
[0027] Example 1
[0028] Methane-rich gas was introduced into a fixed-bed reactor at a flow rate of 10 m³ / h. 3 The catalyst bed is Fe-Al catalyst with a molar ratio of three metal elements of 10:4:3 and a packing density of g / h. The reactor is heated to 800℃, where methane undergoes a cracking reaction on the surface of the Fe-Al catalyst to produce hydrogen and solid carbon. The methane conversion rate is approximately 90%, and the annual hydrogen production is approximately 140,000 cubic meters.
[0029] Example 2
[0030] Methane-rich gas was introduced into a fixed-bed reactor at a flow rate of 20 m³ / h. 3The reactor has a capacity of g / h and uses a Fe-Al catalyst bed with a molar ratio of 10:6:3 for the three metal elements. When the reactor is heated to 700℃, methane undergoes a cracking reaction on the surface of the Fe-Al catalyst at this temperature, producing hydrogen and solid carbon. The methane conversion rate is approximately 80%, and the annual hydrogen production is approximately 250,000 cubic meters.
[0031] Example 3
[0032] Methane-rich gas was introduced into the fluidized bed reactor at a flow rate of 5 m³ / h. 3 The feed rate is g / h, fed from the bottom of the reactor, and the hydrogen product is discharged from the top. The fluidized bed is an Fe-Al catalyst with a molar ratio of the three metal elements of 10:4:3. The reactor is heated to 900℃, at which temperature methane undergoes a cracking reaction on the surface of the Fe-Al catalyst to produce hydrogen and solid carbon. The methane conversion rate is about 90%, and the annual hydrogen production is about 70,000 cubic meters.
[0033] Example 4
[0034] Methane-rich gas was introduced into the fluidized bed reactor at a flow rate of 8 m³ / h. 3 The reactor feeds at a rate of g / h from the bottom, with hydrogen products exiting from the top and spent catalyst and byproduct elemental carbon exiting from the bottom. The fluidized bed is an Fe-Al catalyst with a molar ratio of 10:2:3 for the three metal elements. The reactor is heated to 1000℃, at which temperature methane undergoes a cracking reaction on the surface of the Fe-Al catalyst, producing hydrogen and solid carbon. The methane conversion rate is approximately 80%, and the annual hydrogen production is approximately 100,000 cubic meters.
[0035] Example 5
[0036] Methane-rich gas was introduced into the fluidized bed reactor at a flow rate of 50 m³ / h. 3 The reactor feeds at a rate of g / h from the bottom, with hydrogen products exiting from the top and spent catalyst and byproduct elemental carbon exiting from the bottom. The fluidized bed is an Fe-Al catalyst with a molar ratio of 10:4.4:3 for the three metal elements. The reactor is heated to 950°C, at which temperature methane undergoes a cracking reaction on the surface of the Fe-Al catalyst, producing hydrogen and solid carbon. The methane conversion rate is approximately 90%, and the annual hydrogen production is approximately 700,000 cubic meters.
[0037] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. A method for producing hydrogen from methane through cracking, characterized in that, Includes the following steps: In the reactor, methane is contacted with a solid waste catalyst and reacted to produce hydrogen and solid carbon materials. The solid waste catalyst is prepared using red mud as raw material.
2. The method according to claim 1, characterized in that, The reaction temperature is 600–1000℃; The space velocity of the reaction is 3000–15000 ml·g. -1 ·h -1 .
3. The method according to claim 1, characterized in that, The reaction is carried out at a pressure of 0.1–0.5 MPa.
4. The method according to claim 1, characterized in that, The solid waste catalyst is obtained through the following steps: including a pretreatment stage and a modification and activation stage; The pretreatment stage includes: washing the Bayer red mud to remove surface deposits and soluble salts, and drying it with hot air or natural sun drying to obtain dried red mud; and grinding the dried red mud into red mud powder using a ball mill or other pulverizing equipment. The modification and activation stage includes: mixing red mud powder with dilute sulfuric acid or dilute hydrochloric acid with pH = 5.5-6, and carrying out a leaching reaction at 50-70℃ to dissolve some impurities and expose the surface of active metal oxides. After filtration, the mixture is washed and filtered 5 times with deionized water until the filtrate is approximately neutral. The mixture is then allowed to stand and dry at room temperature for 24 hours, and then calcined at 700℃ for 6 hours in a calcination furnace. After high-temperature calcination, a small amount of water is added in the form of a spray, and the mixture is granulated to 40-80 mesh by rolling and sieving to obtain shaped catalyst particles. The shaped catalyst particles are then dried again in a drying oven at 110℃ to obtain the red mud-based Fe-Al catalyst, i.e., the solid waste catalyst.