多孔催化颗粒积碳消除行为的孔隙尺度模拟

为明晰多孔催化颗粒消碳再生过程中微观孔隙结构与积碳分布特性之间的内在关系，基于格子玻尔兹曼方法、耦合固相更新方法构建消碳反应的孔隙尺度模型，研究孔隙尺度上积碳消除行为引起的孔隙结构的动态演变过程，分析气体稀薄效应下的消碳行为，评估不同孔径和消碳速率对消碳反应特性和传质特性的影响。结果表明：简单孔隙内积碳均匀分布条件下，消碳反应导致轴向产生扩张的孔隙结构，黏性流动的贡献更加显著；消碳过程减弱了气体稀薄效应，降低了传质速率和反应速率；“大孔”和“小孔”内均匀分布的积碳，更容易被均匀地消除，而“中孔”内积碳，入口效应更加显著；高气体稀薄效应和高反应速率下，消碳反应导致简单孔隙结构演变对黏性流动的促进作用比努森扩散更加显著；复杂的随机孔隙结构，同样存在入口效应，并且积碳消除会导致钟型孔径分布的均匀性增强。

Pore scale simulation of coke removal behavior inside a porous catalytic particle

To clarify the relationship between microscopic pore structure and coke distribution during the coke removal and regeneration process of porous catalytic particles, the lattice Boltzmann method coupled with the solid-phase renewal method is developed and the pore-scale model of carbon removal is established to investigate the dynamic evolution of pore structures owing to carbon removal behavior at the pore-scale. Meanwhile, the effects of pore size and coke removal rate on the coke removal reaction characteristics and mass transfer properties are evaluated. The results reveal that the coke removal reaction leads to the axial expanding pore structure and the contribution of viscous flow becomes more significant. The coke removal process weakens the gas rarefaction effect and reduces the mass transfer rate and reaction rate. The coke in the large pore and small pore is easier for the uniform elimination. In contrast, the entrance effect is more significant in the medium pore. Under the condition of high rarefaction effect and high reaction rate, the coke removal reaction impact on viscous flow is more significant in contrast to the Knudsen diffusion. The entrance effect also exists for complex random pore structure and coke removal enhances the uniformity of pore size distribution.