A method for producing carbon monoxide from carbon dioxide using plasma
By using graphite electrode arc plasma technology to react carbon dioxide with a carbon source to generate carbon monoxide at high temperatures, the problems of high energy consumption and complex products in existing technologies have been solved, realizing the generation and industrial application of pure CO.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SINOSTEEL EQUIP & ENG
- Filing Date
- 2024-04-02
- Publication Date
- 2026-06-30
Smart Images
Figure CN118270786B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of chemical gasification technology, and in particular relates to a method for producing carbon monoxide from carbon dioxide using plasma. Background Technology
[0002] Steel, cement, and thermal power are major industrial carbon emitters, making carbon dioxide capture and utilization a top priority. However, the current common practice is to collect carbon dioxide and then release it, without truly achieving the goal of utilization.
[0003] In the chemical industry, CO, as a major component of syngas and various coal gases, is an important raw material for synthesizing a series of basic organic chemical products and intermediates. Almost all basic chemical products can be produced from CO, such as alcohols, acids, anhydrides, esters, ethers, alkanes, and alkenes. As a reducing agent in metallurgy, CO is a primary raw material for blast furnace ironmaking; due to its exothermic reaction characteristics, both blast furnaces and vertical shaft furnaces are indispensable. CO is also a fuel gas in industrial production, playing a crucial role in ensuring the heating of steel rolling furnaces and boiler power generation. Furthermore, carbon monoxide (CO) is commonly used in daily life as a fixative and preservative, such as for fruits, vegetables, and rice, and especially for preserving sashimi; it is also used as a color fixative to give meat a glossy finish. Therefore, carbon monoxide (CO) is a major basic raw material gas in industry, playing a vital role in the national economy. Developing an effective method to reduce carbon dioxide emissions has become an urgent task. Utilizing CO2 to produce CO can achieve the goals of energy storage, carbon sequestration, carbon reduction, and integrated chemical production. Plasma technology, as a highly efficient and environmentally friendly energy technology, provides a new pathway for converting carbon dioxide into carbon monoxide. However, existing plasma-assisted CO conversion methods often require the participation of H2 or CH4 and are carried out under catalytic conditions. The resulting products are mixtures, not a single CO gas. Furthermore, the plasma is mostly obtained using microwave or plasma torch methods, which cannot meet the requirements of industrial production.
[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention
[0005] To address the technical problems of existing technologies that require continuous high temperatures above 700°C to produce CO using only the reaction of C and CO2, which utilizes fossil fuels and introduces new carbon emissions and inefficient energy use, and the need for additional gas separation and purification equipment in other conversion methods, leading to difficulties in industrial CO2 conversion and low utilization rates, this paper proposes a method for producing carbon monoxide from carbon dioxide using plasma.
[0006] The first aspect of the present invention provides a method for producing carbon monoxide from carbon dioxide using plasma. CO2 and a dry carbon source are injected into the arc plasma of a graphite electrode, and an oxidation-reduction reaction occurs at a temperature above 700°C to generate CO.
[0007] The chemical reaction for producing carbon monoxide (CO) from carbon dioxide (CO2) is relatively simple. Mainly, below 100℃, CO2 and C are stable and cannot produce CO. CO can only be produced by heating under standard atmospheric pressure with a certain amount of energy.
[0008] In some embodiments, the carbon source is carbon powder or coal powder.
[0009] In some embodiments, the mass percentage of moisture in the carbon powder or coal powder is <1% to prevent the reactions C+H2O=CO+H2 and CO+H2O=CO2+H2 from occurring, thereby reducing the conversion efficiency of CO2 to CO.
[0010] In some embodiments, the fixed carbon content of the pulverized coal is above 80%.
[0011] In some embodiments, the particle size of the carbon powder or coal powder is less than 2 mm. Fine particle size facilitates injection, avoids nozzle clogging, and increases the specific surface area of the material, increasing the reaction contact area and promoting rapid reaction.
[0012] In some embodiments, the carbon powder or coal powder is injected into the arc plasma of the graphite electrode via a carrier, wherein the carrier is a CO2 carrier.
[0013] In some embodiments, the gas-solid ratio of the CO2 carrier to the graphite or pulverized coal is 10 to 40.
[0014] In some embodiments, the arc plasma is prepared by a plasma furnace, which is a sealed furnace with a metal bottom electrode as the anode and a hollow graphite electrode as the cathode. The furnace body is constructed of high-temperature resistant refractory material, and the furnace body must not only withstand high temperatures but also bear a certain pressure and resist gas erosion.
[0015] In some embodiments, the hollow graphite electrode is used to spray carbon powder or coal powder, and the gas pressure is 0.1 to 0.7 MPa when CO2 carrier gas is injected into the plasma furnace.
[0016] In some embodiments, the amount of CO2 carrier is 1 / 3 of the total amount of CO2 gas, and the remaining 2 / 3 of the CO2 gas is heated and blown into the plasma furnace tangentially to avoid extinguishing the plasma torch flame.
[0017] The principle upon which this invention is based is:
[0018] Plasma is a macroscopically electrically neutral gas composed of positively charged ions, negatively charged ions, and electrons. Under the influence of a high current, CO2 is ionized. The CO2 gas in an ion discharge state reacts with injected carbon powder (C) under high temperature and energy, resulting in a series of reactions. Excess carbon powder (C) ensures that the product is entirely CO gas. Under high temperature or a specific electromagnetic field, CO2 gas molecules can be partially or completely ionized to form plasma. Plasma has high chemical reactivity; under its influence, carbon dioxide molecules are activated and transformed into reactive groups. These reactive groups, through a series of reactions, are ultimately converted into stable carbon monoxide molecules (CO). The specific reaction equations are as follows:
[0019] CO2 + e → CO2 + e-
[0020] CO2 + e- → CO + O
[0021] 2O→O2
[0022] C + O2 → CO
[0023] The final reaction equation is: CO2 + C = 2CO + 75.0 GJ / kmol
[0024] Compared with existing technologies, the technical effects achieved by this invention are as follows:
[0025] (1) This invention utilizes the efficient heating method of electric arc plasma, the flexible technical approach, and the concentrated energy density to impart a certain amount of energy to carbon dioxide. With the addition of excess carbon powder or coal powder of a certain particle size, all CO2 is coupled into carbon monoxide, which is used as a raw material for chemical production to achieve the purpose of carbon fixation. If the gas at the outlet end is used for iron and steel metallurgy, it can be directly blown into the blast furnace or vertical furnace without purification treatment for the reduction of iron oxides. If CO is used for chemical industry, it needs to be purified and then sent to the CO gas holder for storage for chemical use.
[0026] (2) This invention strictly controls the moisture content of carbon powder and coal powder to avoid the participation of water vapor and prevent reactions such as C + H₂O = CO + H₂ and CO + H₂O = CO₂ + H₂. On the one hand, the presence of water molecules reduces the conversion rate of captured CO₂; on the other hand, hydrogen has a molecular weight of only 2, making it the lightest gas in nature, with a standard density (0℃, 101.325KPa) of 0.0899 kg / m³. 3 With a relative density (air, 0℃, 101.325 kPa) of 0.07, it is extremely prone to leakage. Leaked hydrogen will accumulate at the top of the space, hindering subsequent storage and transportation. In contrast, pure carbon monoxide (CO) under standard conditions is a colorless and odorless gas with a relative molecular mass of 28.01 and a density of 1.25 kg / m³. 3It has a density slightly less than air, and its density is 14 times that of hydrogen. Compared to CO and H2, this invention captures all CO2 and converts it into pure CO, which is more conducive to subsequent storage, transportation and use.
[0027] (3) The present invention uses inexpensive graphite electrodes, which have stable performance and long service life, enabling long-cycle operation. It adopts electric arc plasma heating to achieve electrification, which can be flexibly started and stopped, meeting the requirements of industrial production. It can also flexibly utilize green energy, such as wind power and photovoltaic power, to achieve carbon-negative operation. In addition, the graphite electrodes also play the role of raw materials, participating in the reaction of carbon dioxide, which is conducive to the complete conversion of CO2.
[0028] (4) The reaction of CO2 with C upon heating can be calculated using heat load:
[0029] The feed consists of pure CO2 and C, at a temperature of 40°C and a pressure of 7 bar. Ignoring pressure drop, the product yields 1000 m³. 3 Producing carbon monoxide (CO) gas at 1000℃ requires 12.34 MW of energy, equivalent to 1.2 kWh of electricity per cubic meter of CO gas. This is significantly less than the 4.6 kWh required per cubic meter for hydrogen electrolysis, making its economic advantages obvious. Compared to the cost of 0.7 yuan per cubic meter for coal gasification, it also demonstrates high feasibility. This invention not only eliminates carbon dioxide (CO2) but also stores surplus electrical energy, reducing investment and providing the most basic C1 raw material for chemical products. It has significant practical implications for low-carbon, carbon reduction, and carbon sequestration. Attached Figure Description
[0030] Figure 1 This is a process flow diagram and application scenario illustration for producing CO from CO2 by heating C;
[0031] Figure 2 This is a Gibbs free energy equilibrium diagram at different temperatures. Detailed Implementation
[0032] The technical solution of the present invention will be described below with reference to the accompanying drawings and specific embodiments. It should be understood that the one or more steps mentioned in the present invention do not preclude the existence of other methods and steps before or after the combined steps, or that other methods and steps may be inserted between these explicitly mentioned steps. It should also be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Unless otherwise stated, the numbering of each method step is only for the purpose of identifying each method step, and not for limiting the order of each method or limiting the scope of the present invention. Changes or adjustments to their relative relationships, without substantial changes to the technical content, can also be considered as within the scope of the present invention.
[0033] The raw materials and instruments used in the examples are not subject to any specific restrictions on their source; they can be purchased from the market or prepared according to conventional methods known to those skilled in the art.
[0034] Example 1
[0035] The chemical reaction for producing carbon monoxide (CO) from carbon dioxide (CO2) is relatively simple. Mainly, below 100℃, CO2 and C are stable and cannot produce CO. A certain amount of energy must be supplied, and heating under standard atmospheric pressure is required to produce CO. Figure 2 It can be seen that when the temperature exceeds 100℃, the reaction proceeds in a direction favorable to the formation of CO, and when the temperature exceeds 600℃, most of it is already carbon monoxide (CO).
[0036] like Figure 1 As shown, industrially captured carbon dioxide (CO2) gas is introduced into a plasma furnace. The plasma is excited by an electric field. Under the action of the plasma, the CO2 molecules are activated and transformed into active groups. By controlling the reaction conditions, the active groups react with carbon powder to transform into stable carbon monoxide (CO) molecules.
[0037] Specifically, the electrical control system 3 uses a 2MW power supply system at 40℃ for 1000m 3 / h of CO2 carrier loaded with dried toner, with 2000m 3 CO2 gas at a rate of / h is simultaneously bubbled into plasma furnace 1 and reacted at a temperature above 700℃. After the reaction, 6000m³ of CO2 gas can be generated. 3 CO gas, at a temperature of 1000℃, is produced at a rate of / h. The heat generated is exchanged with the CO2 carrier in heat exchanger 2, preheating the CO2. The preheated CO2 then continues the reaction, achieving efficient heat utilization. The generated CO gas can be directly injected into the tuyeres of blast furnace 6 without purification, thus saving coke. Alternatively, it can be directly blown into the direct reduction shaft furnace 7 to react with pellets to produce sponge iron. After further purification in purifier 4, the CO is collected in gas holder 5 and used as raw material gas in chemical production. The entire process is simple and reliable. The CO, after reduction and reaching a temperature of 1000℃, can be directly blown into the direct reduced iron production process in the shaft furnace as the reduction process gas, which can meet the full-load operation of an annual production capacity of 30,000 tons of direct reduced iron.
[0038] The carbon powder has a particle size of less than 2mm and a moisture content of less than 1% by mass. The molar ratio of CO2 to carbon powder is 1:1, or the weight ratio is 3:11. The gas pressure inside the plasma furnace is ≥0.2MPa. The plasma furnace is cylindrical, and the non-carrier CO2 is blown in along the tangential direction of the graphite electrode of plasma furnace 1 to avoid blowing out the plasma torch flame. The power supply uses surplus wind and solar power. Combined with the high efficiency, long lifespan, and lack of extensive cooling characteristics of the graphite electrode arc plasma, it can achieve long-cycle operation and flexible start-stop, meeting the requirements of industrial production.
[0039] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.
Claims
1. A method for producing carbon monoxide from carbon dioxide using plasma, characterized in that, CO2 and a dry carbon source are injected into the arc plasma of a graphite electrode. At a temperature above 700°C, a redox reaction occurs to generate CO. The electric arc plasma is prepared by a plasma furnace, which is a closed furnace with a metal bottom electrode as the anode and a hollow graphite electrode as the cathode. The carbon source is carbon powder or coal powder. The hollow graphite electrode is used to spray carbon powder or coal powder. The carbon powder or coal powder is sprayed into the arc plasma of the graphite electrode through a carrier. The carrier is a CO2 carrier. When CO2 carrier gas is sprayed into the plasma furnace, the gas pressure is 0.1~0.7MPa. The amount of CO2 carrier is 1 / 3 of the total amount of CO2 gas, and the remaining 2 / 3 of the CO2 gas is heated and blown into the plasma furnace along the tangential direction of the plasma furnace.
2. The method according to claim 1, characterized in that, The mass percentage of moisture in the carbon powder or coal powder is <1%.
3. The method according to claim 1, characterized in that, The fixed carbon content of the pulverized coal is above 80%.
4. The method according to claim 1, characterized in that, The particle size of the carbon powder or coal powder is less than 2 mm.
5. The method according to claim 1, characterized in that, The gas-solid ratio of the CO2 carrier to the graphite or pulverized coal is 10 to 40.