Full-cycle process for coal gas carbonaceous components based on integrated co 2 absorption and electrocatalysis

Abstract

The present invention relates to the technical field of carbon dioxide capture and utilization of coal gas. Disclosed is a full-cycle process for coal gas carbonaceous components based on integrated CO2 absorption and electrocatalysis. In the present invention carbon dioxide in coal gas is captured by means of a primary amine solution and / or a secondary amine solution, and electrocatalytic reduction is performed on an absorption liquid to prepare a CO / H2 reducing gas. The absorption liquid is regenerated during the electrocatalytic reduction process, thereby achieving integration of carbon dioxide capture and utilization, simplifying the process, and reducing capture energy consumption. An improved electrolysis process is used to accelerate the generation of the CO / H2 reducing gas, which is then mixed with decarbonized coal gas and is returned to a smelting process for recirculation, thereby improving the reductive performance of the recirculated coal gas, replacing coke as a reducing agent, reducing coke usage, reducing carbon emissions, and fully realizing full-cycle utilization of coal gas carbonaceous components.

Description

Coal gas carbon component full cycle process based on CO2 absorption and electric catalysis integration TECHNICAL FIELD

[0001] The application belongs to the technical field of coal gas carbon dioxide capture and utilization, and particularly relates to a coal gas carbon component full cycle process based on CO2 absorption and electric catalysis integration. BACKGROUND

[0002] With the extensive use of fossil fuels and the increase of industrial activities, global carbon dioxide emissions are increasing year by year. In order to alleviate the negative effects of climate change, carbon capture and utilization (CCU) technology is considered as a solution with industrial application potential. Among various CCU technologies, chemical absorption method is concerned due to its strong selectivity and wide range of use, and has become one of the mainstream technologies for post-combustion carbon dioxide capture. However, chemical absorption method needs to go through regeneration and capture compression steps, and the high energy consumption caused by the cumbersome steps, therefore, optimizing the conversion path of carbon dioxide becomes an important key to promote the development of the technology, which needs more attention and investment in technology research and development.

[0003] CN110305704A discloses a system and method for coupling new energy low energy consumption to realize CO2 capture and utilization. The invention combines CO2 capture and utilization by using a solid adsorbent. After the calcium-based absorbent is used as a reaction catalyst to absorb CO2, CO2 methanation is carried out. However, this scheme has low and unstable absorption capacity, and is difficult to apply to the treatment of blast furnace gas.

[0004] CN112981438A discloses a CO2 electrolysis system for synthesizing gas. The method uses an alkaline solution as an electrolyte, preferably an alkali metal bicarbonate (MHCO3) or carbonate (M2CO3) electrolyte. By changing the reaction conditions, synthesis gas is prepared. This method only includes a CO2 utilization process, and needs to continuously introduce pure CO2 gas for electrolysis, which is separated from CO2 capture, has high energy consumption and high cost.

[0005] The coal gas produced in the steel smelting process contains 6-22% CO2. If the coal gas carbon component full cycle can be realized, this measure will undoubtedly help to reduce carbon emissions. However, the CO2 capture methods disclosed in the prior art limit their application in coal gas carbon component full cycle. How to simply and efficiently remove CO2 from coal gas and realize coal gas carbon component full cycle has not been studied in the field. SUMMARY

[0006] The present application aims to provide a coal gas carbon component full cycle process based on CO2 absorption and electrocatalysis integration.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0008] A coal gas carbon component full cycle process based on CO2 absorption and electrocatalysis integration comprises the following steps:

[0009] The coal gas is introduced into an absorption tower containing a primary amine and / or a secondary amine absorption solution for decarburization, and the absorption solution after decarburization (i.e., a carbon-rich solution) is pumped into an electrolytic cell with a cathode loaded with an electrolytic catalyst, CO / H2 reducing gas is generated by electrolysis and regeneration is completed, the regenerated absorption solution (i.e., a carbon-lean solution) is returned to the absorption tower for repeated use, and the generated CO / H2 reducing gas and the decarburized coal gas are returned to the smelting process for continued use.

[0010] 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; 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 coal gas carbon component full cycle process based on CO2 absorption and electrocatalysis integration is shown in FIG. 1.

[0013] Although there is a method for absorbing CO2 by using organic amine and electrolyzing to produce CO / H2 reducing gas in the prior art, the electrocatalyst used in the electrolysis process is a noble metal, and the electrolysis efficiency is slow, and the slow electrolysis efficiency is difficult to process the CO2 absorption liquid in time, which hinders the application of the organic amine absorbing CO2 and electrolyzing to produce CO / H2 reducing gas in the full cycle of the carbon components of the coal gas, the present application improves the electrocatalyst, not only reduces the cost of the electrocatalyst, but also greatly accelerates the electrolysis efficiency of the CO2 absorption liquid, and can realize the cycle of the CO2 absorption liquid, the absorption of CO2 by the absorption liquid of the primary amine and / or secondary amine, the desorption of CO2 by the specific electrocatalyst catalyzing carbamate, the acceleration of the absorption and conversion of CO2, so as to improve the proportion of CO / H2, improve the reduction performance of the circulating coal gas, reduce the coke consumption, reduce the carbon emission, and realize the full cycle utilization of the carbon components of the coal gas.

[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 primary amine and / or secondary amine containing absorption liquid is 1-5 mol / L.

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

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

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

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

[0021] Generally, the CO in the decarburized coal gas accounts for 30-40 vol.%, and the H2 accounts for 3-5 vol.%, after improving the electrolysis process to accelerate the production of CO / H2 reducing gas, the CO in the circulating coal gas accounts for 35-45%, and the H2 accounts for 13-17%, that is, the volume ratio of CO / H2 in the circulating gas should be 2.3-3.4, so as to improve the reduction performance of the circulating coal gas, reduce the coke consumption by 10-30%, reduce the carbon emission by 50-95%, and reduce the capture energy consumption by 100-196 kJ / mol.

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

[0023] The application absorbs CO2 in the coal gas by using the primary amine and / or secondary amine absorption liquid to generate carbamate and protonated amine, breaks the C-N bond of the carbamate in the cathode of the electrolytic cell through the electrocatalytic reaction, and absorbs protons by using the protonated amine to complete the organic amine regeneration process, so that the electrolytic product CO / H2 is reduced into combustible gas, which can be used as energy material for smelting again, the reducibility of the circulating coal gas is improved, the use of coke is reduced, and the smelting cost of the blast furnace is reduced.

[0024] The coal gas carbon component full cycle process based on the CO2 absorption electrocatalysis integration provided by the application not only can realize the full cycle of the carbon component of the coal gas and reduce the carbon emission in the smelting process, but also has no high energy consumption step in the process. The coal gas carbon component full cycle process provided by the application is energy-saving and emission-reducing, and has great popularization and application value. BRIEF DESCRIPTION OF DRAWINGS

[0025] Fig. 1 is a flow chart of the coal gas carbon component full cycle process based on the CO2 absorption electrocatalysis integration provided by the application. DETAILED DESCRIPTION

[0026] The various exemplary embodiments of the application will now be described in detail, which should not be considered as limiting the application, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the application. It should be understood that the terms described in the application are only for describing the particular embodiments, and are not used to limit the application.

[0027] In addition, for the numerical range in the application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value in the stated range, and any other stated value or intermediate value in the stated range is also included in the application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from 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 this application belongs. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application.

[0029] As used herein, the terms “comprise”, “include”, “have”, “contain”, and the like are open-ended terms, i.e., meaning “including but not limited to”.

[0030] The Ag NPs in Comparative Example 1 of the application are self-made products, and the preparation method is as follows:

[0031] Preparation of Ag NPs: 20 mL of 20 mmol·L-1 AgNO3 solution was prepared, and 20 mL of 20 mmol·L-1 NaBH4 solution was prepared. -1Stir the AgNO3 thoroughly, then quickly add 20 mL of 141.6 mmol·L⁻¹ solution. -1 Stir the sodium citrate solution for 10 min, and after it stabilizes, add 25 mL of 30 mmol·L⁻¹ sodium citrate solution. -1 sodium borohydride solution will Ag + Reduce, stir rapidly for 2 hours, filter and wash, and vacuum dry at 60℃ for 6 hours for later use.

[0032] The electrocatalysts in Examples 1-5 and Comparative Example 2 of this invention are self-made products, and the preparation method is as follows:

[0033] First take 0.1 mmol·L -1 The metal oxide was dissolved in 20 mL of water, and 20 mmol·L⁻¹ was added. -1 The precious metal nitrate was quickly stirred until homogeneous, and then 20 mL of 141.6 mmol·L⁻¹ nitrate was added. -1 Stir the sodium citrate solution for 10 min, and after it stabilizes, add 25 mL of 30 mmol·L⁻¹ sodium citrate solution. -1 The sodium borohydride solution was used to reduce the noble metal ions. The mixture was stirred for 2 hours, filtered and washed, and then vacuum dried at 60°C for 6 hours for later use.

[0034] Taking blast furnace smelting as an example:

[0035] First, blast furnace gas is introduced into an absorbent containing primary and / or secondary amines (concentration of 1-5 mol) at a flow rate of 30 L / min to saturate it. The CO2 loading is 0.5-2.5 mol / L. The saturated absorbent is then pumped into an electrolytic cell for electrolysis. The lean solution after electrolysis is recycled back to the absorption tower for reuse. The CO / H2 reducing gas generated by electrolysis, together with the decarbonized blast furnace gas (the decarbonized blast furnace gas contains 30 vol.% CO and 4 vol.% H2), is returned to the blast furnace as circulating gas.

[0036] Preparation of the electrolytic cell: The electrolytic cell adopts a traditional H-type reaction cell. The cathode uses a glassy carbon electrode coated with catalyst as the working electrode, the anode uses a platinum sheet electrode as the counter electrode, the reference electrode is an Ag / AgCl electrode, and the proton exchange membrane is N117. The preparation process of the working electrode 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. The dispersion is ultrasonically dispersed for 30 min. Then, it is dropped onto the bottom of the glassy carbon electrode (10 mm in diameter) using a pipette. After spin coating and drying, the electrocatalyst is loaded onto the bottom of the glassy carbon electrode at a loading of 1 mg / cm³. 2 .

[0037] Example 1

[0038] The 60wt.% Au-40wt.% WO3 is used as the electrocatalyst, 4M AMP is used as the absorption solution, the electrolysis temperature is 50°C, the applied voltage is -1V vs. RHE, the circulating coal gas contains 45vol.% CO and 15vol.% H2, and the CO / H2 volume ratio is 3. Compared with returning the blast furnace only with the decarburized blast furnace gas, the coke consumption can be reduced by 30%, the carbon emission can be reduced by 95%, and the energy consumption is 196 kJ / mol.

[0039] Example 2

[0040] The 20wt.% In-80wt.% ZrO2 is used as the electrocatalyst, 4M MEA is used as the absorption solution, the electrolysis temperature is 10°C, the applied voltage is -1V vs. RHE, the circulating coal gas contains 41vol.% CO and 13vol.% H2, and the CO / H2 volume ratio is 3.1. Compared with returning the blast furnace only with the decarburized blast furnace gas, the coke consumption can be reduced by 10%, the carbon emission can be reduced by 50%, and the energy consumption is 100 kJ / mol.

[0041] Example 3

[0042] The 40wt.% Ag-60wt.% TiO2 is used as the electrocatalyst, 4M AMP is used as the absorption solution, the electrolysis temperature is 40°C, the applied voltage is -1.5V vs. RHE, the circulating coal gas contains 42vol.% CO and 17vol.% H2, and the CO / H2 volume ratio is 2.4. Compared with returning the blast furnace only with the decarburized blast furnace gas, the coke consumption can be reduced by 15%, the carbon emission can be reduced by 40%, and the energy consumption is 120 kJ / mol.

[0043] Example 4

[0044] The 80wt.% In-20wt.% WO3 is used as the electrocatalyst, 2M MEA is used as the absorption solution, the electrolysis temperature is 60°C, the applied voltage is -1V vs. RHE, the circulating coal gas contains 43vol.% CO and 14vol.% H2, and the CO / H2 volume ratio is 3. Compared with returning the blast furnace only with the decarburized blast furnace gas, the coke consumption can be reduced by 20%, the carbon emission can be reduced by 60%, and the energy consumption is 140 kJ / mol.

[0045] Example 5

[0046] The 60wt.% In-40wt.% WO3 is used as the electrocatalyst, 2M EDA is used as the absorption liquid, the electrolysis temperature is 40°C, the applied voltage is -1V vs. RHE, the circulating coal gas contains 44vol.% CO and 15vol.% H2, and the CO / H2 volume ratio is 2.9. Compared with the case where only the decarburized blast furnace gas is returned to the blast furnace, the coke consumption is reduced by 27%, the carbon emission is reduced by 88%, and the energy consumption is 170kJ / mol.

[0047] Comparative Example 1

[0048] Compared with Example 3, the only difference is that the catalyst loaded on the cathode is replaced by the same mass of Ag NPs, the circulating coal gas contains 32vol.% CO and 8vol.% H2, and the CO / H2 volume ratio is 4. Compared with the case where only the decarburized blast furnace gas is returned to the blast furnace, the coke consumption is reduced by 6%, the carbon emission is reduced by 30%, and the energy consumption is 60kJ / mol.

[0049] Comparative Example 2

[0050] Compared with Example 1, the only difference is that the catalyst loaded on the cathode is replaced by the same mass of 10wt.% Au-90wt.% WO3, the circulating coal gas contains 27vol.% CO and 12vol.% H2, and the CO / H2 volume ratio is 2.2. Compared with the case where only the decarburized blast furnace gas is returned to the blast furnace, the coke consumption is reduced by 5%, the carbon emission is reduced by 20%, and the energy consumption is 30kJ / mol.

[0051] The above-described examples only describe the preferred modes of the present application and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those of ordinary skill in the art should fall within the protection scope of the present application as defined by the claims.

Claims

1. A coal gas carbonaceous component full cycle process based on CO2 absorption electrocatalytic integration, characterized in that, The method comprises the following steps: The coal gas is introduced into an absorption tower containing a primary amine and / or a secondary amine absorption solution for decarburization, the absorption solution after decarburization is pumped into an electrolytic cell with a cathode loaded with an electrolytic catalyst, CO / H2 reducing gas is generated by electrolysis and regeneration is completed, the regenerated absorption solution is returned to the absorption tower for repeated use, and the generated CO / H2 reducing gas is returned to a smelting process together with the decarburized coal gas 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; and the carrier is one or more of ZrO2, TiO2 and WO3.

2. The process for integrated electrocatalytic CO2 absorption based total coal gas carbonaceous components recycling according to claim 1, characterized in that, The coal gas includes blast furnace gas or shaft furnace gas.

3. The process for integrated electrocatalytic CO2 absorption based total coal gas carbonaceous components recycling according to claim 1, characterized in that, The primary amine includes monoethanolamine and 2-amino-2-methyl-1-propanol; and the secondary amine includes diethanolamine.

4. The process for integrated electrocatalytic CO2 absorption based total coal gas carbonaceous components recycling according to claim 1, characterized in that, The concentration of the primary amine and / or the secondary amine in the primary amine and / or secondary amine absorption solution is 1-5 mol / L.

5. The process for integrated electrocatalytic CO2 absorption based total coal gas carbonaceous components recycling according to claim 1, characterized in that, The mass fraction of the active component in the electrolytic catalyst is 20-80%.

6. The process for integrated electrocatalytic CO2 absorption based total coal gas carbonaceous components recycling according to claim 1, characterized in that, The temperature during electrolysis is 10-60℃, and the applied voltage is 0-2V vs. RHE.

7. The process for integrated electrocatalytic CO2 absorption based total coal gas carbonaceous components recycling according to claim 1, characterized in that, The CO / H2 reducing gas is discharged above the cathode, mixed with the decarburized coal gas, and returned to the smelting process for recycling.

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