Molecular insights into the role of char-bound hydrogen in char-NO reactions under high pressures: A reactive molecular dynamics simulation study
Molecular insights into the role of char-bound hydrogen in char-NO reactions under high pressures: A reactive molecular dynamics simulation study
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DOI：
10.1016/j.fuel.2021.121997
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发表时间：
2022-01
期刊：
影响因子：
7.4
通讯作者：
Dikun Hong;Ming Lei;S. Yue;Chunbo Wang
中科院分区：
文献类型：
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作者：
Dikun Hong;Ming Lei;S. Yue;Chunbo Wang
本文采用反应分子动力学（ReaxFF MD）模拟研究了加压氧燃料燃烧（POFC）条件下炭结合氢在炭- no反应中的作用。研究了不同压力和温度下炭结合氢对NO的化学吸附、N2的生成、炭-NO反应动力学以及炭结构的影响。结果表明，碳结合氢阻碍了NO的化学吸附，抑制了CN的生成。随着压力的增加，碳结合氢在NO化学吸附中的作用减弱。NO与含h炭反应生成了大量的H2O，证明了炭结合氢为NO转化为N2提供了另一种途径，特别是在高压下。测定了NO与含h炭反应过程中NO的化学吸附活化能为174 kJ/mol， n2的生成活化能为126 kJ/mol。ReaxFF MD模拟结果与以往的实验值和DFT值吻合较好。炭结合氢使NO的化学吸附活化能和n2的生成活化能分别提高了40%和29%。研究了炭结合氢在炭气化和炭结构中的作用。炭结合氢减少了炭的消耗，CO是炭气化的主要产物。炭的O/C和N/C比值结果表明，炭结合氢对CO的解吸影响不大。通过分析炭结构的动态演化，发现炭结合氢抑制N-down化学吸附NO。
In the present work, the role of char-bound hydrogen in char-NO reaction under pressurized oxy-fuel combustion (POFC) conditions was studied using the reactive molecular dynamics (ReaxFF MD) simulations. The effects of char-bound hydrogen on the chemisorption of NO, formation of N2, kinetics of char-NO reaction, and structure of char at different pressures and temperatures were investigated. The results show that the char-bound hydrogen hindered the chemisorption of NO, and inhibited the generation of CN. The role of char-bound hydrogen in the chemisorption of NO weakened with the increase in pressure. Considerable amount of H2O was generated during the reaction of NO with H-containing char, which proves that char-bound hydrogen provided another channel for the conversion of NO to N2, especially at high pressures. The activation energies of the chemisorption of NO and the formation of N2during the reaction of NO with H-containing char were determined to be 174 and 126 kJ/mol, respectively. The ReaxFF MD simulation results were in good agreement with previous experimental and DFT values. The char-bound hydrogen increased the activation energies of the chemisorption of NO and the formation of N2by 40% and 29%, respectively. The role of char-bound hydrogen in char gasification and char structure were also examined. The char-bound hydrogen reduced the consumption of char, and CO was the main product from char gasification. The results of the O/C and N/C ratios of char indicate that char-bound hydrogen had little effect on the desorption of CO. By analyzing the dynamic evolution of char structure, it is found that char-bound hydrogen inhibited N-down chemisorption of NO.