Experimental study on the catalytic effect of AAEMs on NO reduction during coal combustion in O2/CO2 atmosphere
During oxy-fuel combustion, the NO emission can be inhibited by the strongly reductive atmosphere caused by the high proportion of gasification reaction, which is a unique feature that differs from air combustion. The alkali and alkaline earth metals (AAEMs) contained in coal ash can catalyze gasifi...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2024-03-01
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| Series: | Carbon Capture Science & Technology |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2772656823000635 |
| _version_ | 1827321705667756032 |
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| author | Xiaojian Zha Zewu Zhang Long Yang Zhenghong Zhao Fan Wu Xiaoshan Li Cong Luo Liqi Zhang |
| author_facet | Xiaojian Zha Zewu Zhang Long Yang Zhenghong Zhao Fan Wu Xiaoshan Li Cong Luo Liqi Zhang |
| author_sort | Xiaojian Zha |
| collection | DOAJ |
| description | During oxy-fuel combustion, the NO emission can be inhibited by the strongly reductive atmosphere caused by the high proportion of gasification reaction, which is a unique feature that differs from air combustion. The alkali and alkaline earth metals (AAEMs) contained in coal ash can catalyze gasification reactions, promoting the homogeneous reduction process of NO. Besides, AAEMs also suppress NO emission through catalyzing the NO heterogeneous reduction by char (CNO). Both catalytic effects of AAEMs have been studied at relatively low temperatures (below 1000 °C) in a simple atmosphere (pure CO2). However, the catalytic effect of AAEMs on NO reduction is still unclear during oxy-fuel combustion due to the more complex reaction atmosphere, higher reaction temperatures, and the presence of gasification reactions. In this work, the effect of different factors on the catalytic effect of AAEMs under O2/CO2 atmosphere is investigated. Results show that the order of the catalytic effect of AAEMs on NO reduction is Na > K > Ca > Mg, with the highest NO reduction efficiency of 30 % for Na. The catalytic effect of Na on NO reduction weakened as the temperature increases. When the temperature increased from 1373 K to 1573 K, the NO reduction efficiency (ηNO) of Na decreased from 30 % to 6 %. While the catalytic effect of Na on NO reduction strengthened as the oxygen concentration increases. When the O2 concentrations increased from 10 vol.% to 30 vol.%, the ηNO values of Na increased from 27 % to 35 %. The K-Na binary additive is more effective in reducing NO emissions than K and Na alone, with NO reduction efficiency as high as 46.8 % at a K/ Na is 1:2. Besides, the Raman test results reveal that K contributed to the conversion of amorphous carbon into a regular graphite crystal structure. Na disrupted the graphite structure resulting in more defective points appearing in the graphite lattice. These results are expected to provide a theoretical reference and new insights for the reduction of NO emission during oxy-fuel combustion. |
| first_indexed | 2024-03-11T10:46:18Z |
| format | Article |
| id | doaj.art-c47f30cf58f74e40bac5e5e959d6eec3 |
| institution | Directory Open Access Journal |
| issn | 2772-6568 |
| language | English |
| last_indexed | 2024-04-25T01:11:48Z |
| publishDate | 2024-03-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Carbon Capture Science & Technology |
| spelling | doaj.art-c47f30cf58f74e40bac5e5e959d6eec32024-03-10T05:13:29ZengElsevierCarbon Capture Science & Technology2772-65682024-03-0110100159Experimental study on the catalytic effect of AAEMs on NO reduction during coal combustion in O2/CO2 atmosphereXiaojian Zha0Zewu Zhang1Long Yang2Zhenghong Zhao3Fan Wu4Xiaoshan Li5Cong Luo6Liqi Zhang7State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, ChinaCorresponding author.; State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, ChinaState Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, ChinaState Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, ChinaState Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, ChinaState Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, ChinaState Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, ChinaState Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, ChinaDuring oxy-fuel combustion, the NO emission can be inhibited by the strongly reductive atmosphere caused by the high proportion of gasification reaction, which is a unique feature that differs from air combustion. The alkali and alkaline earth metals (AAEMs) contained in coal ash can catalyze gasification reactions, promoting the homogeneous reduction process of NO. Besides, AAEMs also suppress NO emission through catalyzing the NO heterogeneous reduction by char (CNO). Both catalytic effects of AAEMs have been studied at relatively low temperatures (below 1000 °C) in a simple atmosphere (pure CO2). However, the catalytic effect of AAEMs on NO reduction is still unclear during oxy-fuel combustion due to the more complex reaction atmosphere, higher reaction temperatures, and the presence of gasification reactions. In this work, the effect of different factors on the catalytic effect of AAEMs under O2/CO2 atmosphere is investigated. Results show that the order of the catalytic effect of AAEMs on NO reduction is Na > K > Ca > Mg, with the highest NO reduction efficiency of 30 % for Na. The catalytic effect of Na on NO reduction weakened as the temperature increases. When the temperature increased from 1373 K to 1573 K, the NO reduction efficiency (ηNO) of Na decreased from 30 % to 6 %. While the catalytic effect of Na on NO reduction strengthened as the oxygen concentration increases. When the O2 concentrations increased from 10 vol.% to 30 vol.%, the ηNO values of Na increased from 27 % to 35 %. The K-Na binary additive is more effective in reducing NO emissions than K and Na alone, with NO reduction efficiency as high as 46.8 % at a K/ Na is 1:2. Besides, the Raman test results reveal that K contributed to the conversion of amorphous carbon into a regular graphite crystal structure. Na disrupted the graphite structure resulting in more defective points appearing in the graphite lattice. These results are expected to provide a theoretical reference and new insights for the reduction of NO emission during oxy-fuel combustion.http://www.sciencedirect.com/science/article/pii/S2772656823000635Oxy-fuel combustionAAEMsCatalytic reductionNO emissionChar gasification reaction |
| spellingShingle | Xiaojian Zha Zewu Zhang Long Yang Zhenghong Zhao Fan Wu Xiaoshan Li Cong Luo Liqi Zhang Experimental study on the catalytic effect of AAEMs on NO reduction during coal combustion in O2/CO2 atmosphere Carbon Capture Science & Technology Oxy-fuel combustion AAEMs Catalytic reduction NO emission Char gasification reaction |
| title | Experimental study on the catalytic effect of AAEMs on NO reduction during coal combustion in O2/CO2 atmosphere |
| title_full | Experimental study on the catalytic effect of AAEMs on NO reduction during coal combustion in O2/CO2 atmosphere |
| title_fullStr | Experimental study on the catalytic effect of AAEMs on NO reduction during coal combustion in O2/CO2 atmosphere |
| title_full_unstemmed | Experimental study on the catalytic effect of AAEMs on NO reduction during coal combustion in O2/CO2 atmosphere |
| title_short | Experimental study on the catalytic effect of AAEMs on NO reduction during coal combustion in O2/CO2 atmosphere |
| title_sort | experimental study on the catalytic effect of aaems on no reduction during coal combustion in o2 co2 atmosphere |
| topic | Oxy-fuel combustion AAEMs Catalytic reduction NO emission Char gasification reaction |
| url | http://www.sciencedirect.com/science/article/pii/S2772656823000635 |
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