Early Events of the Carburization of Fe Nanoparticles in Ethylene Pyrolysis: Reactive Force Field Molecular Dynamics Simulations
Early Events of the Carburization of Fe Nanoparticles in Ethylene Pyrolysis: Reactive Force Field Molecular Dynamics Simulations
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DOI：
10.1021/acs.jpcc.8b01481
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发表时间：
2018-05
影响因子：
3.7
通讯作者：
Xiangyang Wang;Xianggui Xue;Chaoyang Zhang
中科院分区：
文献类型：
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作者：
Xiangyang Wang;Xianggui Xue;Chaoyang Zhang
烃类热解过程中过渡金属的渗碳是石化工业中常见的腐蚀现象。然而，渗碳机制的早期事件仍不清楚。通过反应性ReaxFF力场分子动力学模拟，揭示了Fe纳米颗粒在乙烯（C2H4）热解过程中渗碳的早期阶段。结果表明，C2H4在铁表面的化学吸附和离解是渗碳腐蚀的关键步骤。首先，C2H4分子被化学吸附在Fe纳米颗粒表面。之后，通过C-H键断裂，C2H4发生连续脱氢生成C2Hx （x = 0-3）。最后得到非晶富c碳化物FeC3.39。碳化物的形成过程分为四个连续重复的阶段，包括纳米铁表面C2H4的化学吸附和脱氢，纳米铁表面和纳米铁内部C2Hx的扩散和聚合形成短碳链。
The carburization of transition metals in hydrocarbon pyrolysis is a common corrosion phenomenon in the petrochemical industry. Nevertheless, early events of carburization mechanism remain still unclear. The present work reveals the details at earlier stages of the Fe nanoparticles carburization in ethylene (C2H4) pyrolysis with reactive ReaxFF force field molecular dynamics simulations. Our results show that the chemisorption and dissociation of C2H4 on Fe surfaces are crucial steps to the carburization corrosion. First of all, C2H4 molecules are chemically adsorbed on the surface of the Fe nanoparticle. Afterward, continuous dehydrogenation of C2H4 occurs by C–H bond break to form C2Hx (x = 0–3). And finally, an amorphous C-rich carbide FeC3.39 is obtained. The carbide formation proceeds in four sequential and repetitive stages, including chemisorption and dehydrogenation of C2H4 on the surface of the Fe nanoparticle, diffusion and polymerization of C2Hx to form short C chains on the surface and in the ...