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A top-down kinetic modeling methodology is proposed using the in-house developed software tool ‘KASTER’. As a case study, it is applied in the assessment of methane steam reforming (MSR) kinetics on a Ni catalyst, including water-gas shift (WGS) as a side-reaction. The complexity of the reaction mechanism is gradually enhanced, leading ultimately, to a microkinetic model. The reactor equations are solved in a transient manner, preventing the crucial numerical challenges encountered in the steady-state solution. The model providing the best balance between detail and significance was found to be of the Langmuir-Hinshelwood-Hougen-Watson (LHHW) type accounting for dissociative adsorption. In this model, the rate-determining steps of MSR and WGS are CO formation and COOH formation, respectively. While the microkinetic variant indicated that both CH dissociative adsorption and CO formation are kinetically relevant steps in MSR, CO formation is found to be rate determining at 923 K using the adopted methodology.

A top‐down methodology for kinetic model construction including regression against experimental data is proposed using “KASTER.” As a case study, it is applied in the assessment of methane steam reforming (MSR) including water–gas shift (WGS) on a Ni catalyst at 923 K. The degree of detail in the reaction mechanism and the corresponding model is gradually enhanced, typically ranging from a simple power law to a microkinetic model. The reactor equations are solved transiently, preventing the numerical challenges encountered in the steady‐state solution, particularly for microkinetic models. The microkinetic variant indicated that CH4 dissociative adsorption and CO formation are kinetically relevant steps in MSR, while COOH formation is rate‐determining in WGS. However, the model providing the best balance between detail accounted for and parameter significance corresponded to a Langmuir–Hinshelwood–Hougen–Watson (LHHW) mechanism accounting for dissociative adsorption, with CO formation and COOH formation as rate‐determining steps for MSR and WGS, respectively.

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