Measuring Spatiotemporal Concentration and Temperature Profiles in a Tubular Fixed‐Bed Reactor for CO 2 Methanation

ABSTRACT In this work, spatiotemporally resolved concentration and temperature profiles were measured in a tubular reactor with a Ni/ catalyst for the methanation process, also considering the intermediate product carbon monoxide. In addition to stationary investigations, the reactor was dynamically operated through transient step changes of the feed from inert to reactive conditions at temperatures between and and a flow rate of and . Spatiotemporal profiles were recorded using a mass spectrometer with a cycle time of and a narrow axial resolution of up to . Consistently, the obtained profiles relaxed to the steady‐state and revealed distinct internal transient kinetic effects. The temporal evolution of the concentration profiles demonstrated the progression of reactant conversion and product formation, accompanied by a temporally changing selectivity through the transient phase and an initial temperature overshoot, attributed to changes in surface coverage during the transient phase. These spatiotemporal measurements provide valuable insights into the internal reactor behavior under transient conditions that cannot be derived from end‐of‐pipe measurements alone, and therefore serve as a robust database for the validation of detailed reactor models and ultimately enhance the understanding of the dynamically operated methanation process.