(267f) On the Effectiveness Factor Modeling for Mass Transfer-Limited Reaction Networks in Industrial Catalysis

Bo Jin, Xiaoxiang Zhu, and Willian R. Licht

Steam-methane reforming (SMR) is an important industrial catalysis application and much work has been devoted to studying the reaction kinetics both at the molecular level and the macroscopic scales. Bridging the micro- and macroscopic activities in the catalyst is the mass transfer from the process gas into/out of the catalyst particles. Reforming reactions at high temperature are so fast that the systems are diffusion limited even at extremely fine laboratory scales which attempt to probe the intrinsic reaction kinetics. As a result, accurate incorporation of the mass transfer factors strongly affect the quantification of intrinsic reaction kinetics, the catalyst performance, and furthermore the design of reforming plants.

While a full reaction-diffusion model could be numerically solved for the coupled SMR reaction network to quantify the effectiveness factor accurately, such an approach is prohibited in practical applications due to the need of numerous iterations and the high computational cost. In this work, we present a novel approach based on perturbation analysis to analytically derive the solution of effectiveness factor for the SMR reaction network. With little computational cost, the algebraic analytical solution closely matches the numerical solution of the full diffusion-reaction model. The analytical solution is incorporated and demonstrated in a reformer tube simulation. Enabled by the analytical solution, parameter estimation in lab-conducted measurements as well as programs for plant engineering and design can efficiently and correctly take into account the mass transfer limitations in the catalyst. The approach presented here is generic and also applicable to other reaction networks.