A full circulation process of coal gas carbonaceous components based on integrated CO2 absorption and electrocatalysis

Abstract

The present invention discloses a full-circulation process for the carbonaceous components of coal gas based on integrated CO2 absorption and electrocatalysis, belonging to the technical field of coal gas carbon dioxide capture and utilization. The present invention captures carbon dioxide from coal gas using a primary and / or secondary amine solution, electrocatalytically reduces the absorption liquid to produce CO / H2 reducing gas, and regenerates the absorption liquid during the electrocatalytic reduction process, achieving integrated carbon dioxide capture and utilization, streamlining the process, and reducing capture energy consumption. An improved electrolysis process is used to accelerate the production of CO / H2 reducing gas, which is then mixed with decarbonized coal gas and returned to the smelting process for recycling, thereby improving the reduction performance of the circulating coal gas. This replaces coke as a reducing agent, reducing coke usage and carbon emissions, and fully realizing the full recycling of the carbonaceous components of coal gas.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal gas carbon dioxide capture and utilization, and specifically relates to a coal gas carbonaceous component full circulation process based on integrated CO2 absorption and electrocatalysis. Background Art

[0002] With the widespread use of fossil fuels and the increase in industrial activities, global carbon dioxide emissions are increasing year by year. In order to mitigate the negative impacts of climate change, carbon capture and utilization (CCU) technology is considered to be a solution with potential for industrial application. Among various CCU technologies, chemical absorption has attracted much attention due to its strong selectivity and wide range of applications, and has become one of the mainstream technologies for capturing carbon dioxide after combustion. However, the chemical absorption method requires steps such as regeneration and capture compression. The cumbersome steps result in high energy consumption. Therefore, optimizing the conversion pathway of carbon dioxide has become an important key to promoting the development of this technology, and it needs to receive more attention and investment in technology research and development.

[0003] CN110305704A discloses a system and method for CO2 capture and utilization that utilizes new energy sources and low energy consumption. This invention combines CO2 capture and utilization using a solid adsorbent. The method uses a calcium-based absorbent as a catalyst to absorb CO2 and then methanize it. However, this solution has a low absorption capacity and is unstable, making it difficult to apply to blast furnace gas treatment.

[0004] CN112981438A discloses a CO2 electrolysis system for producing synthesis gas. The method uses an alkaline solution as an electrolyte, preferably an alkali metal bicarbonate (MHCO3) or carbonate (M2CO3) electrolyte, and produces synthesis gas by changing the reaction conditions. The method only includes a CO2 utilization process and requires continuous introduction of pure CO2 gas for electrolysis and separation from the CO2 capture phase, resulting in high energy consumption and high cost.

[0005] The coal gas produced during the steel smelting process contains 6 to 22% CO2. If the full circulation of the carbonaceous components of the coal gas can be achieved, this measure will undoubtedly help reduce carbon emissions. However, the CO2 capture methods disclosed in the existing technology limit their application in the full circulation of the carbonaceous components of the coal gas. There is no relevant research in this field on how to simply and efficiently remove CO2 from the coal gas and achieve the full circulation of the carbonaceous components of the coal gas. Summary of the Invention

[0006] The present invention aims to provide a full-circulation process for the carbonaceous components of coal gas based on integrated CO2 absorption and electrocatalysis. This process captures carbon dioxide using a primary and / or secondary amine solution, reducing regeneration energy consumption. The captured solution is then used as an electrolyte for electrolysis, combining carbon dioxide capture and absorption to achieve integrated carbon dioxide capture and utilization. In the blast furnace reaction, the coal gas is directly captured with organic amines and then electrolyzed in situ. An improved electrolysis process is then used to accelerate the mixing of CO / H2 reducing gas with the decarbonized coal gas, which is then returned to the smelting process for recycling. This improves the reducing properties of the circulating coal gas, replaces coke as a reducing agent, reduces coke usage, reduces carbon emissions, and fully realizes the full recycling of the carbonaceous components of coal gas.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A full-cycle process for carbonaceous components of coal gas based on integrated CO2 absorption and electrocatalysis, comprising the following steps:

[0009] The coal gas is passed into an absorption tower containing a primary amine and / or secondary amine absorption liquid for decarbonization. The decarbonized absorption liquid (i.e., carbon-rich solution) is pumped into an electrolytic cell with an electrolytic catalyst loaded on the cathode, where CO / H2 reducing gas is generated by electrolysis and regeneration is completed. The regenerated absorption liquid (i.e., carbon-depleted solution) is returned to the absorption tower for reuse, and the generated CO / H2 reducing gas and the decarbonized coal gas are returned together to the smelting process for continued use;

[0010] The electrolytic catalyst consists of an active component and a carrier, wherein the active component is one or more of In, Au and Ag; and the carrier is one or more of ZrO2, TiO2 and WO3.

[0011] In, Au, and Ag are noble metals that tend to generate CO.

[0012] The flow chart of the full cycle process of coal gas carbonaceous components based on CO2 absorption and electrocatalysis integration is shown in Figure 1 .

[0013] Although there is a method in the prior art of using organic amines to absorb CO2 and electrolyze to produce CO / H2 reducing gas, the electrocatalyst used in the electrolysis process is a precious metal, and the electrolysis efficiency is slow. The slow electrolysis efficiency makes it difficult to timely process the CO2 absorption liquid, which hinders the application of organic amines to absorb CO2 and electrolyze to produce CO / H2 reducing gas in the full circulation of coal gas carbonaceous components. The present invention improves the electrocatalyst, which not only reduces the cost of the electrocatalyst, but also greatly accelerates the electrolysis efficiency of the CO2 absorption liquid, and can realize the circulation of the CO2 absorption liquid. The absorption liquid of primary amine and / or secondary amine is used to absorb CO2, and then a specific electrocatalyst is used to catalyze the desorption of CO2 by carbamate, thereby accelerating the absorption and conversion of CO2, thereby increasing the CO / H2 ratio, improving the reduction performance of the circulating coal gas, reducing the amount of coke used, reducing carbon emissions, and realizing the full recycling of coal gas carbonaceous components.

[0014] Preferably, the coal gas includes blast furnace gas or shaft furnace gas.

[0015] Preferably, the primary amine includes monoethanolamine (MEA) and 2-amino-2-methyl-1-propanol (AMP); and the secondary amine includes diethanolamine (EDA).

[0016] Preferably, the concentration of the primary amine and / or secondary amine in the absorption liquid containing the primary amine and / or secondary amine is 1 to 5 mol / L.

[0017] Preferably, the mass fraction of the active component in the electrolytic catalyst is 20 to 80%.

[0018] Preferably, during the electrolysis process, the temperature is 10-60° C., and the applied voltage is 0-2 V vs. RHE.

[0019] Preferably, the CO / H2 reducing gas is discharged above the cathode, mixed with the decarbonized coal gas and returned to the smelting process for recycling.

[0020] Preferably, the CO / H2 reducing gas is discharged above the cathode, mixed with the decarbonized coal gas and returned to the smelting process for recycling.

[0021] Usually, CO accounts for 30-40 vol.% and H2 accounts for 3-5 vol.% in the coal gas after decarbonization. After improving the electrolysis process to accelerate the production of CO / H2 reducing gas, the CO proportion in the circulating coal gas is 35-45%, and the H2 proportion is 13-17%. That is, the CO / H2 volume ratio in the circulating gas should be 2.3-3.4, thereby improving the reduction performance of the circulating coal gas, which can reduce the coke consumption by 10-30%, reduce carbon emissions by 50-95%, and reduce the capture energy consumption by 100-196 kJ / mol.

[0022] The beneficial technical effects of the present invention are as follows:

[0023] The present invention absorbs CO2 in coal gas through an absorption liquid containing primary amine and / or secondary amine to generate carbamate and protonated amine, breaks the CN bond of the carbamate through an electrocatalytic reaction in the cathode of the electrolytic cell, and simultaneously the protonated amine absorbs protons to complete the organic amine regeneration process, which is returned to the absorption tower for reuse. The electrolysis product CO / H2 reducing gas is a combustible gas and can be reused as an energy material for smelting, thereby improving the reducing property of the circulating coal gas, thereby reducing the use of coke and reducing the blast furnace smelting cost.

[0024] The present invention provides a comprehensive carbonaceous component recycling process for coal gas, based on integrated CO2 absorption and electrocatalysis. This process not only fully recycles the carbonaceous components of coal gas, reducing carbon emissions during the smelting process, but also eliminates high-energy-consuming steps. This comprehensive carbonaceous component recycling process for coal gas, which offers significant energy savings and emission reductions, has significant potential for widespread application. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a flow chart of the full circulation process of coal gas carbonaceous components based on integrated CO2 absorption and electrocatalysis of the present invention. DETAILED DESCRIPTION

[0026] Various exemplary embodiments of the present invention are now described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention.

[0027] In addition, for numerical ranges in the present invention, it is understood that each intervening value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any stated value or stated range, and any other stated value or intervening value in the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention.

[0029] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0030] The Ag NPs in Comparative Example 1 of the present invention are homemade products, and the preparation method is as follows:

[0031] Preparation of Ag NPs: Prepare 20 mL of 20 mmol·L -1AgNO3 was stirred evenly and 20mL141.6mmol·L was quickly added -1 The sodium citrate solution was stirred for 10 min, and after stabilization, 25 mL of 30 mmol·L -1 Sodium borohydride solution to Ag + Reduce, stir rapidly for 2 h, filter and wash, and vacuum dry at 60 °C for 6 h for later use.

[0032] The electrocatalysts in Examples 1 to 5 of the present invention and Comparative Example 2 are homemade products, and the preparation method is as follows:

[0033] First, take 0.1mmol·L -1 The metal oxide was dissolved in 20 mL of water and 20 mmol·L -1 The precious metal nitrate was stirred quickly and evenly, and 20 mL of 141.6 mmol·L -1 Stir the sodium citrate solution for 10 min, and add 25 mL of 30 mmol·L -1 The noble metal ions were reduced with sodium borohydride solution, stirred for 2 h, filtered and washed, and vacuum dried at 60 °C for 6 h for later use.

[0034] Take blast furnace smelting as an example:

[0035] First, blast furnace gas is introduced into an absorption liquid containing primary amine and / or secondary amine (concentration is 1-5 mol) at a flow rate of 30 L / min to achieve saturated absorption, wherein the CO2 loading amount is 0.5-2.5 mol / L. The saturated absorption liquid is pumped into an electrolytic cell for electrolysis, and the lean liquid after electrolysis is circulated back to the absorption tower for recycling. The CO / H2 reducing gas generated by electrolysis and the decarbonized blast furnace gas (CO accounts for 30 vol.%, H2 accounts for 4 vol.%) are returned to the blast furnace as circulating gas for use.

[0036] Preparation of the electrolytic cell: The electrolytic cell adopts a traditional H-type reaction cell, a glassy carbon electrode coated with a catalyst is used as the working electrode at the cathode, a platinum electrode is used as the counter electrode at the anode, an Ag / AgCl electrode is used as the reference electrode, and the proton exchange membrane is N117. The working electrode preparation process is as follows: first, the prepared electrocatalyst is ultrasonically dispersed in a mixed dispersion of deionized water, isopropanol, and 5 wt.% Nafion in a volume ratio of 1:1:0.01, ultrasonicated for 30 minutes, and then dropped onto the bottom of a glassy carbon electrode (10 mm in diameter) with a pipette. After spin coating, it is dried to load the electrocatalyst on the bottom of the glassy carbon electrode. The electrocatalyst loading is 1 mg / cm 2 .

[0037] Example 1

[0038] Using 60wt.% Au-40wt.% WO3 as the electrocatalyst, 4MAMP as the absorption liquid, the electrolysis temperature is 50℃, the applied voltage is -1V vs.RHE, CO accounts for 45vol.%, H2 accounts for 15vol.%, and the CO / H2 volume ratio is 3. Compared with using only decarbonized blast furnace gas to return to the blast furnace, it can reduce the coke consumption by 30%, reduce carbon emissions by 95%, and reduce energy consumption by 196kJ / mol.

[0039] Example 2

[0040] 20wt.% In-80wt.% ZrO2 was used as the electrocatalyst, 4M MEA was used as the absorption liquid, the electrolysis temperature was 10°C, the applied voltage was -1V vs. RHE, CO accounted for 41vol.%, H2 accounted for 13vol.%, and the CO / H2 volume ratio was 3.1. Compared with using only decarbonized blast furnace gas to return to the blast furnace, it can reduce the coke consumption by 10%, reduce carbon emissions by 50%, and reduce energy consumption by 100kJ / mol.

[0041] Example 3

[0042] 40wt.% Ag-60wt.% TiO2 was used as the electrocatalyst, 4MAMP was used as the absorption liquid, the electrolysis temperature was 40°C, the applied voltage was -1.5V vs. RHE, CO accounted for 42vol.%, H2 accounted for 17vol.%, and the CO / H2 volume ratio was 2.4. Compared with using only decarbonized blast furnace gas to return to the blast furnace, it can reduce the coke consumption by 15%, reduce carbon emissions by 40%, and reduce energy consumption by 120kJ / mol.

[0043] Example 4

[0044] 80wt.% In-20wt.% WO3 is used as the electrocatalyst, 2M MEA is used as the absorption liquid, the electrolysis temperature is 60℃, the applied voltage is -1V vs.RHE, CO accounts for 43vol.%, H2 accounts for 14vol.%, and the CO / H2 volume ratio is 3. Compared with using only decarbonized blast furnace gas to return to the blast furnace, it can reduce the coke consumption by 20%, reduce carbon emissions by 60%, and reduce energy consumption by 140kJ / mol.

[0045] Example 5

[0046] 60wt.% In-40wt.% WO3 was used as the electrocatalyst, 2M EDA was used as the absorption liquid, the electrolysis temperature was 40°C, the applied voltage was -1V vs. RHE, CO accounted for 44vol.%, H2 accounted for 15vol.%, and the CO / H2 volume ratio was 2.9. Compared with using only decarbonized blast furnace gas to return to the blast furnace, it can reduce the coke consumption by 27%, reduce carbon emissions by 88%, and reduce energy consumption by 170kJ / mol.

[0047] Comparative Example 1

[0048] Compared with Example 3, the only difference is that the catalyst loaded on the cathode is replaced with Ag NPs of equal mass, CO accounts for 32 vol.%, H2 accounts for 8 vol.%, and the CO / H2 volume ratio is 4. Compared with using only decarbonized blast furnace gas to return to the blast furnace, it can reduce the amount of coke by 6%, reduce carbon emissions by 30%, and reduce energy consumption by 60 kJ / mol.

[0049] Comparative Example 2

[0050] Compared with Example 1, the only difference is that the catalyst loaded on the cathode is replaced with an equal mass of 10wt.% Au-90wt.% WO3, CO accounts for 27vol.%, H2 accounts for 12vol.%, and the CO / H2 volume ratio is 2.2. Compared with only using decarbonized blast furnace gas to return to the blast furnace, it can reduce the amount of coke by 5%, reduce carbon emissions by 20%, and reduce energy consumption by 30kJ / mol.

[0051] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A full circulation process of coal gas carbonaceous components based on integrated CO2 absorption and electrocatalysis, characterized in that: The following steps are involved: The coal gas is passed into an absorption tower containing primary amine and / or secondary amine absorption liquid for decarbonization. After decarbonization, the absorption liquid is pumped into an electrolytic cell with an electrolytic catalyst loaded on the cathode, where CO / H2 reducing gas is generated by electrolysis and regeneration is completed. The regenerated absorption liquid is returned to the absorption tower for reuse, and the generated CO / H2 reducing gas and the decarbonized coal gas are returned to the smelting process for continued use. The electrolytic catalyst is composed of an active component and a carrier, wherein the active component is one or more of In, Au and Ag; the carrier is one or more of ZrO2, TiO2 and WO3; The mass fraction of the active component in the electrolytic catalyst is 20 to 80%; The electrolytic catalyst is loaded on the cathode in a manner of preparing the electrolytic catalyst into a dispersion liquid and coating the dispersion liquid on the bottom of the cathode.

2. The full circulation process of coal gas carbonaceous components based on integrated CO2 absorption and electrocatalysis according to claim 1 is characterized in that: The coal gas includes blast furnace gas or shaft furnace gas.

3. The full circulation process of coal gas carbonaceous components based on integrated CO2 absorption and electrocatalysis according to claim 1 is characterized in that: The primary amines include monoethanolamine and 2-amino-2-methyl-1-propanol; the secondary amines include diethanolamine.

4. The full circulation process of coal gas carbonaceous components based on integrated CO2 absorption and electrocatalysis according to claim 1 is characterized in that: The concentration of the primary amine and / or secondary amine in the absorption liquid containing the primary amine and / or secondary amine is 1-5 mol / L.

5. The full circulation process of coal gas carbonaceous components based on integrated CO2 absorption and electrocatalysis according to claim 1 is characterized in that: During the electrolysis process, the temperature is 10-60° C., and the applied voltage is 0-2 V vs. RHE.

6. The full circulation process of coal gas carbonaceous components based on integrated CO2 absorption and electrocatalysis according to claim 1 is characterized in that: The CO / H2 reducing gas is discharged above the cathode, mixed with the decarbonized coal gas and returned to the smelting process for recycling.

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