Abstract: The nonisothermal effectiveness factor (E. F. ) for reaction with kinetics r = kcm/(1 + Kc)a can be improved by catalysts with nonuniform activity distribution. The optimal distribution function in one-dimensional model with which the E. F. can be maximized is a δ-function which means that the activity of the catalyst should be concentrated on a layer with negligible thickness at a precise location x from the center of pellets. The general equations for predicting the value of x and the maximum E. F. as a function of thermodynamic, kinetic and transport parameters are derived and they can be given explicitly in the case of a = 0, m=a or isothermal reaction. For reactions with positive order kinetics the optimal position of the activity locates on the surface of the pellet in the case of endothermic or weakly exothermic heat of the reactions, and it moves towards the center as the exothermic heat of reaction or the activity energy gets larger. But for negative order or bimolecular Langmuir-Hinshelwood kinetics, it usually locates in the pellets except for severe endothermic or diffusion-control reaction. Both finite thickness of the active layer and a deviation from the optimal location x decrease the value of the E. F. It was shown numerically that the E. F. decreases slightly with an active layer at the inner side of x but seriously at outer side.

摘要： 本文讨论了一维多孔性催化剂颗粒在非等温情况下活性组份的最佳分布.活性组份集中在离颗粒中心某一距离(?)处的无限薄层上可得到最大的有效因子ηmax.该最佳位置决定于非等温效应、传质阻力以及反应速率的相对大小.文中给出了确定该位置和最大有效因子的分析表达式.得到的ηmax皆恒大于或等于一.活性分布偏离最佳分布或活性层厚度增大皆使有效因子减小;且活性层偏向最佳位置的内侧有效因子减小较少、而偏向最佳位置外侧有效因子急剧减小.