DFT study on NO reduction with CO catalyzed by CaO in carbonation stage of calcium looping process
Global CO2 concentration rapidly increases over the past few centuries, particularly in recent decades, and the greenhouse effect is sharply accelerated by the increase of CO2 emissions. CO2 emissions are mainly produced from fossil fuel combustion, in particular coal-fired power plants. Calcium loo...
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| Format: | Article |
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Editorial Office of Journal of China Coal Society
2023-10-01
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| Series: | Meitan xuebao |
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| Online Access: | http://www.mtxb.com.cn/article/doi/10.13225/j.cnki.jccs.2022.1754 |
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| author | Leizhe CHU Shoubing CHAI Yingjie LI |
| author_facet | Leizhe CHU Shoubing CHAI Yingjie LI |
| author_sort | Leizhe CHU |
| collection | DOAJ |
| description | Global CO2 concentration rapidly increases over the past few centuries, particularly in recent decades, and the greenhouse effect is sharply accelerated by the increase of CO2 emissions. CO2 emissions are mainly produced from fossil fuel combustion, in particular coal-fired power plants. Calcium looping, i.e. the carbonation/calcination cycles of CaO, is one of the most promising CO2 capture technologies for coal-fired power plant. At the same time, coal-fired power plants are also one of the main sources of NOx emissions. CO can be used as a reducing agent for NO due to its low cost and low toxicity. CaO is a suitable catalyst for NO reduction by CO. The combustion of biomass is used to provide the required energy for the decomposition of CaCO3 in the calciner. Few unburned char and CaO flow into the carbonator, where the unburned char reacts with O2 in the flue gas to generate CO. Thus, the simultaneous NO removal and CO2 capture in the carbonator of the calcium looping process can be realized. However, the reaction mechanism of the effect of CaO on NO removal by CO in the carbonation stage is unclear. The mechanism of NO reduction with CO catalyzed by CaO in the carbonation stage is investigated by the density functional theory (DFT) calculations. The structural, adsorption, and reaction path parameters, including atomic layout, bond length, adsorption energy, and energy barrier of CO and NO molecules on the CaO (100) surface, are determined. The optimal adsorption sites of CO and NO molecules on the CaO (100) surface are O-top sites, and the adsorption energies are −0.35 and −0.79 eV, respectively. The CO and NO adsorption energies on the CaO (100) surface in the presence of CO2 are −0.36 and −0.20 eV, respectively. The co-adsorption of CO and NO molecules appears feasible on the CaO (100) surface, while CO2 exhibits obvious inhibition for the co-adsorption. The reaction path of NO reduction by CO on the CaO (100) surface undergoes two elementary reaction stages: CO2 formation and adsorption, and N2 generation. Finally, one N2 molecule and three \begin{document}${\rm{CO}}_3^{2-} $\end{document} ions are formed, with a total energy barrier of 11.08 eV. CO2 formation and adsorption (R→IM1→IM2) are the rate-determining steps of the whole reaction process. |
| first_indexed | 2024-03-09T01:22:17Z |
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| id | doaj.art-2c96bbe24edf4f59b46d7106b1515578 |
| institution | Directory Open Access Journal |
| issn | 0253-9993 |
| language | zho |
| last_indexed | 2024-03-09T01:22:17Z |
| publishDate | 2023-10-01 |
| publisher | Editorial Office of Journal of China Coal Society |
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| series | Meitan xuebao |
| spelling | doaj.art-2c96bbe24edf4f59b46d7106b15155782023-12-10T09:33:28ZzhoEditorial Office of Journal of China Coal SocietyMeitan xuebao0253-99932023-10-0148114205421210.13225/j.cnki.jccs.2022.17542022-1754DFT study on NO reduction with CO catalyzed by CaO in carbonation stage of calcium looping processLeizhe CHU0Shoubing CHAI1Yingjie LI2Shuifa Group Co., Ltd., Jinan 250101, ChinaSchool of Energy and Power Engineering, Shandong University, Jinan 250061, ChinaSchool of Energy and Power Engineering, Shandong University, Jinan 250061, ChinaGlobal CO2 concentration rapidly increases over the past few centuries, particularly in recent decades, and the greenhouse effect is sharply accelerated by the increase of CO2 emissions. CO2 emissions are mainly produced from fossil fuel combustion, in particular coal-fired power plants. Calcium looping, i.e. the carbonation/calcination cycles of CaO, is one of the most promising CO2 capture technologies for coal-fired power plant. At the same time, coal-fired power plants are also one of the main sources of NOx emissions. CO can be used as a reducing agent for NO due to its low cost and low toxicity. CaO is a suitable catalyst for NO reduction by CO. The combustion of biomass is used to provide the required energy for the decomposition of CaCO3 in the calciner. Few unburned char and CaO flow into the carbonator, where the unburned char reacts with O2 in the flue gas to generate CO. Thus, the simultaneous NO removal and CO2 capture in the carbonator of the calcium looping process can be realized. However, the reaction mechanism of the effect of CaO on NO removal by CO in the carbonation stage is unclear. The mechanism of NO reduction with CO catalyzed by CaO in the carbonation stage is investigated by the density functional theory (DFT) calculations. The structural, adsorption, and reaction path parameters, including atomic layout, bond length, adsorption energy, and energy barrier of CO and NO molecules on the CaO (100) surface, are determined. The optimal adsorption sites of CO and NO molecules on the CaO (100) surface are O-top sites, and the adsorption energies are −0.35 and −0.79 eV, respectively. The CO and NO adsorption energies on the CaO (100) surface in the presence of CO2 are −0.36 and −0.20 eV, respectively. The co-adsorption of CO and NO molecules appears feasible on the CaO (100) surface, while CO2 exhibits obvious inhibition for the co-adsorption. The reaction path of NO reduction by CO on the CaO (100) surface undergoes two elementary reaction stages: CO2 formation and adsorption, and N2 generation. Finally, one N2 molecule and three \begin{document}${\rm{CO}}_3^{2-} $\end{document} ions are formed, with a total energy barrier of 11.08 eV. CO2 formation and adsorption (R→IM1→IM2) are the rate-determining steps of the whole reaction process.http://www.mtxb.com.cn/article/doi/10.13225/j.cnki.jccs.2022.1754calcium loopingcarbonation stageco2 captureno reduction by codensity functional theory |
| spellingShingle | Leizhe CHU Shoubing CHAI Yingjie LI DFT study on NO reduction with CO catalyzed by CaO in carbonation stage of calcium looping process Meitan xuebao calcium looping carbonation stage co2 capture no reduction by co density functional theory |
| title | DFT study on NO reduction with CO catalyzed by CaO in carbonation stage of calcium looping process |
| title_full | DFT study on NO reduction with CO catalyzed by CaO in carbonation stage of calcium looping process |
| title_fullStr | DFT study on NO reduction with CO catalyzed by CaO in carbonation stage of calcium looping process |
| title_full_unstemmed | DFT study on NO reduction with CO catalyzed by CaO in carbonation stage of calcium looping process |
| title_short | DFT study on NO reduction with CO catalyzed by CaO in carbonation stage of calcium looping process |
| title_sort | dft study on no reduction with co catalyzed by cao in carbonation stage of calcium looping process |
| topic | calcium looping carbonation stage co2 capture no reduction by co density functional theory |
| url | http://www.mtxb.com.cn/article/doi/10.13225/j.cnki.jccs.2022.1754 |
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