Modelling the phosphorus dynamics of VPO catalyst during n-butane oxidation: A μ-reactor study

Production of maleic anhydride from n-butane is carried out in large fixed-bed reactors, which face a multitude of challenges, amongst them the removal of heat produced by the reaction, alongside a transient increase in activity due to phosphorus loss from the catalyst, causing a shift in selectivities and loss in target product yield. Improved modelling can aid in a better understanding of the involved processes, such that operating policies can be optimized. However, this necessitates the coupling of models for all subprocesses, that are parameterised independently of one another. To date, especially the phosphorus dynamics are not well understood and lack models to describe them. Experiments involving mu -reactor phosphorus dosing under transport limitation-free conditions are reported, investigating the underlying mechanisms of the phosphorus dynamics. Based on this data, an activity model comprising only four parameters is developed. Results indicate that a site-blocking mechanism plays a role in the phosphorus dynamics.