Ni-Catalyzed steam methane reforming (SMR) is widely used in energy and chemical engineering, but the confusion about vastly different SMR kinetic data has lasted for half a century. Towards solving the puzzle, the intrinsic mechanism of SMR is examined by performing density functional theory computations and transition state theory analyses on 80 elementary reaction steps involved in SMR over Ni(111). A microkinetic model is developed by combining the thermochemical data of the elementary reactions with a continuous stirring tank reactor model. The microkinetic model is used to investigate the reaction pathways, the rate determining steps and the abundances of surface species. Reaction rates predicted by the microkinetic model are in good agreement with the experimental data obtained under very different temperature and pressure conditions. An analytical expression of the SMR rate is derived based on the dominant reaction pathway and the abundances of surface species. The rate equation is verified to accurately reflect the microkinetic modeling. Applying the analytical rate equation yields a coherent explanation of the seemingly incompatible experimental data on the reaction orders of CH₄, H₂O and H₂ and the activation energy of SMR. The rate equation is very useful for the optimization of the operating conditions of SMR.

中文翻译：

---

基本反应路径研究和推导的宏观动力学模型，用于统一理解镍催化的蒸汽甲烷重整

镍催化的蒸汽甲烷重整（SMR）在能源和化学工程中得到了广泛的应用，但是有关千篇一律的SMR动力学数据的混淆已经持续了半个世纪。为了解决这个难题，通过对Ni（111）上SMR涉及的80个基本反应步骤进行密度泛函理论计算和过渡态理论分析，研究了SMR的内在机理。通过将基本反应的热化学数据与连续搅拌釜反应器模型相结合，建立了微动力学模型。微动力学模型用于研究反应途径，速率确定步骤和表面物种的丰度。通过微动力学模型预测的反应速率与在非常不同的温度和压力条件下获得的实验数据高度吻合。基于主要的反应途径和表面物质的丰度，得出SMR速率的分析表达式。速率方程被验证以准确反映微动力学模型。应用分析速率方程可对CH的反应阶数看似不相容的实验数据做出连贯的解释_{如图4所示}，H ₂ O和H ₂与SMR的活化能有关。速率方程对于优化SMR的工作条件非常有用。