A two-zone model (1D-2Z) for the estimation of the effective reaction rates in monoliths with non-uniform coating is presented in this contribution. The model relies on the idea of splitting the cross section of the coating in two zones that can be modelled as independent zones with diffusion (and simultaneous reaction) in a single direction (1D). One of the zones is considered a slab, while the variable diffusivity model (1D-VD), whose predictive capabilities has been largely tested in previous works for a great variety of kinetic expressions and catalyst geometries, is applied to the other. The performance of the 1D-2Z model, as well as the results from approximate methods from literature are assessed for three kinetic expressions: a first order reaction, as an elementary kinetics, and two more challenging cases defined by Langmuir-Hinshelwood-Hougen-Watson expressions: one of them with a moderate inhibition effect, and the other with such an effect on the verge of the onset of multiple steady states. Square and triangular channel cross-sections presenting different degrees of non-uniform coating are considered. It was found that the 1D-2Z model is highly accurate, leading to errors in the estimation of the effectiveness factors below 8.5% in all the cases analyzed, for the entire range of Thiele modulus. Simultaneously, a noticeable decrease in computational demand can be achieved from the use of the 1D-2Z model, in comparison to the previous simplifying approaches.

此贡献提供了一个两区域模型（1D-2Z），用于估计具有不均匀涂层的整料中的有效反应速率。该模型基于将涂层的横截面分为两个区域的想法，可以将这些区域建模为在单个方向（1D）上具有扩散（和同时反应）的独立区域。其中一个区域被认为是平板，而可变扩散率模型（1D-VD）的预测能力已在先前的工作中针对各种动力学表达式和催化剂几何形状进行了广泛测试，而另一区域则被应用。针对三种动力学表达式，评估了1D-2Z模型的性能以及来自文献的近似方法的结果：一阶反应，作为基本动力学，Langmuir-Hinshelwood-Hougen-Watson表达式定义了另外两个更具挑战性的案例：其中一个具有中等抑制作用，而另一种则对多种稳定状态的发作具有这种作用。考虑呈现不同程度的不均匀涂层的正方形和三角形通道横截面。已发现，在整个Thiele模量范围内，在所有分析的情况下1D-2Z模型都是高度准确的，导致有效性因子的估计误差低于8.5％。同时，与以前的简化方法相比，使用1D-2Z模型可以实现计算需求的显着减少。考虑呈现不同程度的不均匀涂层的正方形和三角形通道横截面。结果发现，在整个Thiele模量范围内，1D-2Z模型的准确性很高，在所有分析情况下，导致有效性因子的估算误差均低于8.5％。同时，与以前的简化方法相比，使用1D-2Z模型可以实现计算需求的显着减少。考虑呈现不同程度的不均匀涂层的正方形和三角形通道横截面。已发现，在整个Thiele模量范围内，在所有分析的情况下1D-2Z模型都是高度准确的，导致有效性因子的估计误差低于8.5％。同时，与以前的简化方法相比，使用1D-2Z模型可以实现计算需求的显着减少。