Modeling of the Methanation Reaction Under Transient Conditions Based on Spatially and Temporally Resolved Operando DRIFTS Data

In the transient operation of decentralized power-to-gas plants, catalyst dynamics can play a crucial role. For the improved description of such dynamics, the rate affecting step (RAS) approach was developed by Langer et al. Following this approach, in this work, a kinetic model for the methanation reaction over an industrial Ni/Al₂O₃ methanation catalyst was derived and parametrized using data from a unique laboratory reactor. This reactor setup was specifically developed and built within the priority program SPP2080 “DynaKat” (German Research Foundation), aiming to collect spatially and temporally resolved DRIFTS absorbance data of catalyst surface intermediates. This data was used to tune the performance of the derived RAS model and to evaluate its prediction accuracy. For most scenarios investigated, also including sudden variations in feed composition such as H₂ and CO₂ drop out/in scenarios and variations in space velocity, the model describes the changes in surface coverage of formate and adsorbed CO reasonably well. Thus, in this work, a first-of-its-kind methodology for including operando DRIFTS data in a parameter estimation routine for a reaction kinetic model is presented. The results are promising and prove the feasibility of this approach, thereby illustrating future opportunities for its use in high-fidelity reaction kinetic modeling.