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摘要: 基于量子化学密度泛函理论和过渡态理论研究了含酮基团对煤焦异相还原NO的影响及其产物发生氧脱附的微观反应机理。计算结果表明，NO更易于吸附在含酮基团煤焦表面。椅形含酮基团强化了煤焦异相还原NO；锯齿形含酮煤焦表面与NO异相反应决速步能垒值（495.45 kJ/mol）大于锯齿形纯碳基煤焦表面与NO决速步能垒值（331.32 kJ/mol），基于锯齿形含酮煤焦模型中的氧浓度不在利于NO还原的范围内而不易于NO的还原。中间产物P1在无CO存在情况下，较纯碳基煤焦表面更易于发生氧脱附而产生表面缺陷；在CO存在条件下，含酮煤焦表面为氧脱附过程提供自由活性位点，降低了过程能垒消耗。Abstract: Based on the density functional theory of quantum chemistry and transition state theory, reaction mechanism of heterogeneous reaction of ketone char with NO and oxygen desorption of the products were examined. The results indicate that NO is more easily adsorbed on surface of the ketone char. The ketone group of armchair enhances the char heterogeneous reduction of NO; On account of oxygen concentration in the ketone of zigzag char may not be within the range where is beneficial to reduction of NO, the energy barrier value of heterogeneous reduction of ketone coal char and NO (495.45kJ/mol) is higher than that of the pure carbon-based char and NO (331.32 kJ/mol). Without the presence of CO, the P1 of intermediate products is more prone to oxygen desorption than the pure carbon-based char, and surface defects are produced. With the presence of CO, the ketone char provides surface free active sites for the oxygen desorption process, which reduces energy barrier of the process.
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Key words:
- ketone group /
- NO /
- CO /
- surface defect /
- oxygen desorption
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图 2 NO在armchair形含酮煤焦表面的吸附结构示意图
Figure 2 Adsorption configurations of NO on ketone of armchair char surface
(a): N1-down-C3-CS(Eads=-376.21 kJ/mol); (b): N2O2-side-on-CS(Eads=-606 kJ/mol)
图 3 armchair形含酮煤焦与NO反应路径示意图
Figure 3 Diagram of reaction path between ketone of armchair char and NO
图 4 armchair形含酮煤焦异相还原NO的反应势能
Figure 4 Potential energy of heterogeneous reduction of ketone of armchair char and NO
图 5 NO在zigzag形含酮煤焦表面吸附结构示意图
Figure 5 Adsorption configurations of NO on ketone of zigzag char surface
(a): O1-down-CS(Eads=-663.05 kJ/mol); (b): O2-down-CS(Eads=-89.27 kJ/mol)
图 6 zigzag形含酮煤焦表面与NO反应路径示意图
Figure 6 Diagram of reaction path between ketone of zigzag char and NO
图 7 zigzag形含酮煤焦异相还原NO的反应势能
Figure 7 Potential energy of heterogeneous reduction of ketone of zigzag char and NO
图 8 P1发生表面缺陷以及CO存在条件下的氧脱附机理示意图
Figure 8 Surface defects of P1 and the mechanism of oxygen removal with the presence of CO
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[1] 肖韡, 李宇, 肖萌, 王俊超, 范卫东.高温下氧气氛对煤焦还原NO影响机理研究[J].锅炉技术, 2011, 42(5):1-6. http://or.nsfc.gov.cn/bitstream/00001903-5/66967/1/1000002161153.pdfXIAO Wei, LI Yu, XIAO Meng, WANG Jun-chao, FAN Wei-dong. Influence mechanism of oxygen concentration on heterogeneous reduction of nitric oxide by char under high temperature[J]. Boil Technol, 2011, 42(5):1-6. http://or.nsfc.gov.cn/bitstream/00001903-5/66967/1/1000002161153.pdf [2] AND H G, FAN L S. Reduction of nitric oxide from combustion flue gas by bituminous coal char in the presence of oxygen[J]. Ind Eng Chem Res, 2003, 42(12):2536-2543. doi: 10.1021/ie020693n [3] DONG L, GAO S Q, SONG W L, XU G W. Experimental study of NO reduction over biomass char[J]. Fuel Process Technol, 2007, 88(7):707-715. doi: 10.1016/j.fuproc.2007.02.005 [4] 张秀霞. 焦炭燃烧过程中氮转化机理与低NOx燃烧技术的开发[D]. 杭州: 浙江大学, 2012. http://www.wanfangdata.com.cn/details/detail.do?_type=degree&id=Y2215089ZHANG Xiu-xia. Nitrogen conversion mechanism during char combustion and develepment of low NOx technology[D]. Hangzhou: Zhejiang University, 2012. http://www.wanfangdata.com.cn/details/detail.do?_type=degree&id=Y2215089 [5] 高正阳, 杨维结, 阎维平.煤焦催化HCN还原NO的反应机理[J].燃料化学学报, 2017, 45(9):1043-1048. http://manu60.magtech.com.cn/rlhxxb/CN/abstract/abstract19083.shtmlGAO Zheng-yang, YANG Wei-jie, YAN Wei-ping. Reaction mechanism of NO reduction with HCN catalyzed by char[J]. J Fuel Chem Technol, 2017, 45(9):1043-1048. http://manu60.magtech.com.cn/rlhxxb/CN/abstract/abstract19083.shtml [6] FRANKCOMBE T J, BHATIA S K, SMITH S C. Ab initio modelling of basal plane oxidation of graphenes and implications for modelling char combustion[J]. Carbon, 2002, 40(13):2341-2349. doi: 10.1016/S0008-6223(02)00147-1 [7] CHEN N, YANG R T. Ab initio molecular orbital calculation on graphite selection of molecular system and model chemistry[J]. Carbon, 1998, 36(7/8):1061-1070. https://www.sciencedirect.com/science/article/pii/S0008622302003810 [8] FRANCES H Y, RALPH T Y. Ab initio molecular orbital study of adsorption of atomic hydrogen on graphite:Insight into hydrogen storage in carbon nanotubes[J]. Carbon, 2002, 40(3):437-444. doi: 10.1016/S0008-6223(01)00199-3 [9] 朱恒毅. 煤燃烧过程中氮转化机理的量子化学研究[D]. 北京: 华北电力大学, 2016. http://www.wanfangdata.com.cn/details/detail.do?_type=degree&id=Y3114426ZHU Heng-yi. Quantum chemistry research on nitrogen conversion mechanism during the combustion process of coal[D]. Bejing: North China Electric Power University, 2016. http://www.wanfangdata.com.cn/details/detail.do?_type=degree&id=Y3114426 [10] CHEN N, YANG R T. Ab initio molecular orbital study of the unified mechanism and pathways for gas-carbon reactions[J]. J Phys Chem A, 1998, 102(102):6348-6356. https://www.researchgate.net/publication/231662110_Ab_Initio_Molecular_Orbital_Study_of_the_Unified_Mechanism_and_Pathways_for_Gas-Carbon_Reactions [11] ZHANG X X, ZHOU Z J, ZHOU J H, LIU J Z, CEN K F. Density functional study of no desorption from oxidation of nitrogen containing char by O2[J]. Combust Sci Technol, 2012, 184(4):445-455. doi: 10.1080/00102202.2011.648031 [12] HE P, ZHANG X B, PENG X L, JIANG X M, WU J, CHEN N C. Interaction of elemental mercury with defective carbonaceous cluster[J]. J Hazard Mater, 2015, 300:289-297. doi: 10.1016/j.jhazmat.2015.07.017 [13] SANDER M, RAJ A, INDERWILDI O, KRAFT M, KURETI S, BOCKHORN H. The simultaneous reduction of nitric oxide and soot in emissions from diesel engines[J]. Carbon, 2009, 47(3):866-875. doi: 10.1016/j.carbon.2008.11.043 [14] DA COSTA L M, STOYANOV S R, GUSAROV S, TAN X, GRAY M R, STYKER J M. Density functional theory investigation of the contributions of π-π stacking and hydrogen-bonding interactions to the aggregation of model asphaltene compounds[J]. Energy Fuels, 2012, 26(5):2727-2735. doi: 10.1021/ef202010p [15] SUN F, ZHANG J X, TIAN Y. Calculation of alloying effect of Ruthenium in Ni-based single-crystal superalloys[J]. Comput Mater Sci, 2012, 60(3):163-167. https://www.sciencedirect.com/science/article/pii/S0927025612001966 [16] GAO Z Y, YANG W J, DING X L, GANG L, Y W P. Support effects in single atom iron catalysts on adsorption characteristics of toxic gases (NO2, NH3, SO3 and H2S)[J]. Appl Surf Sci, 2018, 36(7/8):1061-1070. https://www.researchgate.net/publication/322944354_Support_effects_on_adsorption_and_catalytic_activation_of_O2_in_single_atom_iron_catalysts_with_graphene-based_substrates [17] RADOVIC L R, CAMILA V, MORA V, ADOLFO J A, SALGADO C, ANTONIO B. Graphene functionalization:Mechanism of carboxyl group formation[J]. Carbon, 2018, 40(3):437-444. https://www.sciencedirect.com/science/article/pii/S0008622317313453 [18] 朱恒毅.煤焦热解过程中产生NH3的量子化学研究[J].煤炭转化, 2017, 40(6):6348-6356. http://www.oalib.com/paper/4967661ZHU Heng-yi. Quantum chemistry study on NH3 formation in the process of char pyrolysis[J]. Coal Conv, 2017, 40(6):6348-6356. http://www.oalib.com/paper/4967661 [19] ZHANG H, LIU J X, LIU J G, LUO L, JIANG X M. DFT study on the alternative NH3 formation path and its functional group effect[J]. Fuel, 2018, 184(4):445-455. https://www.sciencedirect.com/science/article/pii/S0016236117313935 [20] ZHANG H, JIANG X M, LIU J X, SHEN J. Application of density functional theory to the nitric oxide heterogeneous reduction mechanism in the presence of hydroxyl and carbonyl groups[J]. Energy Convers Manage, 2014, 300:289-297. https://www.sciencedirect.com/science/article/pii/S0196890414002684 [21] CHAPARALA S V, RAJ A. Reaction mechanism for the oxidation of zigzag site on polycyclic aromatic hydrocarbons in soot by O2[J]. Combust Flame, 2016, 165(1):21-33. https://www.sciencedirect.com/science/article/pii/S0010218012001848 [22] SINGH R I, MEBEL A M, FRENKLACH M. Oxidation of graphene-edge six-and five-member rings by molecular oxygen[J]. J Phys Chem A, 2015, 119(28):7528-7547. doi: 10.1021/acs.jpca.5b00868 -
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