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This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.A nearly isothermal millistructured fixed-bed reactor was used to investigate the kinetics of the selective oxidation of n-butane to maleic anhydride. In addition to the investigation of a broad range of industrially relevant conditions, the focus was on the influence of the reaction products on the kinetics. For this purpose, a saturator for the accurate dosing of the target product MA was developed. The experimental data were used to derive a reaction network comprising the by-products acetic and acrylic acid. Additionally, the inhibition of the associated reactions by reactants and products was investigated.

Detailed modeling of the oxidation of n-butane to maleic anhydride can help improve the process knowledge and facilitate the development of optimization strategies. Unfortunately, none of the kinetics published in the literature can satisfactorily describe the formation of the most important byproducts: CO and CO2. Based on qualitative findings, we derived different kinetic approaches (Eley–Rideal, Langmuir–Hinshelwood, and Mars and van Krevelen). With a mathematical model of the used millistructured fixed-bed laboratory reactor, these were adapted to the experimental results over a wide range of industrially relevant operating conditions. A comparison of the results suggests that the kinetics can be best described with a redox approach, according to Mars and van Krevelen, derived under the assumption of three different active sites. In this context, the aforementioned description of CO/CO2 formation can be significantly improved, even with a simplified reaction network. The key is to include information on the role of the usually neglected byproducts acetic and acrylic acid.

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