李婉莹, 陈良勇. 化学链甲烷氧化偶联界面反应路径和晶格氧传递的分子动力学模拟[J]. 燃料化学学报(中英文), 2024, 52(6): 820-830. DOI: 10.1016/S1872-5813(23)60412-8
引用本文: 李婉莹, 陈良勇. 化学链甲烷氧化偶联界面反应路径和晶格氧传递的分子动力学模拟[J]. 燃料化学学报(中英文), 2024, 52(6): 820-830. DOI: 10.1016/S1872-5813(23)60412-8
LI Wanying, CHEN Liangyong. Surface reaction and lattice oxygen transfer in chemical looping oxidative coupling of methane: Molecular dynamics simulations[J]. Journal of Fuel Chemistry and Technology, 2024, 52(6): 820-830. DOI: 10.1016/S1872-5813(23)60412-8
Citation: LI Wanying, CHEN Liangyong. Surface reaction and lattice oxygen transfer in chemical looping oxidative coupling of methane: Molecular dynamics simulations[J]. Journal of Fuel Chemistry and Technology, 2024, 52(6): 820-830. DOI: 10.1016/S1872-5813(23)60412-8

化学链甲烷氧化偶联界面反应路径和晶格氧传递的分子动力学模拟

Surface reaction and lattice oxygen transfer in chemical looping oxidative coupling of methane: Molecular dynamics simulations

  • 摘要: 本研究采用分子动力学模拟的方法计算八种金属氧化物催化剂-载氧体CL-OCM反应性能,并对性能最优的Mn2O3开展反应时间和颗粒尺寸的研究。结果表明,适当延长反应时间有利于提高 C2H4 选择性; C/O=1 是Mn2O3的理想尺寸。基于以上结果分析了Mn2O3 CL-OCM界面反应路径和晶格氧传递问题,以揭示反应机理。CH3 *气相二聚化生成C2H6的是CL-OCM最主要的碳偶联路径。除此之外,还存在两条碳偶联路径,均由CH2 *引发。CH3 *与OH*表面结合生成甲醇是CL-OCM副反应的先决步骤,抑制甲醇生成是提高CL-OCM反应C2选择性的关键。晶格氧存在转化,表面晶格氧是甲烷活化的活性氧。晶格氧数量差异及体相晶格氧迁移阻力差异是导致CH4转化率和C2选择性不同的主要原因。该研究为CL-OCM催化剂-载氧体的机理探究提供新的方法。

     

    Abstract: Chemical looping oxidative coupling of methane (CL-OCM) is a promising methodology for ethylene production from methane. This article utilizes molecular dynamic (MD) simulation to assess the performance of eight metal oxide catalytic oxygen carriers in CL-OCM reactions. It also investigates the impact of reaction time and particle size on the efficiency of the most effective Mn2O3 COC. The results indicate that extending the reaction time appropriately enhances C2H4 selectivity and a C/O ratio of 1 is found to be the optimal size for Mn2O3-based CL-OCM. Furthermore, surface reactions and lattice oxygen transfer are analyzed by MD simulation in Mn2O3-based CL-OCM, providing deeply insights into the reaction mechanism. The findings reveal that the gas-phase dimerization of CH3 * to form C2H6 serves as the primary carbon coupling pathway in CL-OCM. In addition, there are two other carbon coupling pathways, both initiated by CH2 *. Methanol formation through surface combination of CH3 * and OH* represents an initial step in CL-OCM side reactions. Therefore, inhibiting methanol formation is crucial for enhancing C2 selectivity in CL-OCM. There exists a transformation of lattice oxygen and surface lattice oxygen plays a key role in methane activation. The quantity of lattice oxygen and difference in bulk lattice oxygen migration resistance are major factors influencing variations CH4 conversion and C2 selectivity. This study provides a new way to reaction mechanism exploration related to CL-OCM catalytic oxygen carriers.

     

/

返回文章
返回