Single pellet profile reactor for measuring concentration and temperature patterns in porous catalyst pellets

Understanding coupled transport and reaction phenomena within porous catalyst pellets is crucial for the optimization of heterogeneous catalytic processes. Nonetheless, experimental access to intra-pellet concentration profiles under industrially relevant conditions remains limited. In this work, we present a second-generation single-pellet profile reactor (SPPR) that enables simultaneous measurement of intra-pellet concentration profiles and surface temperature distributions. The gas composition inside the pellet is measured using a movable sampling capillary and mass spectrometry analysis. The combination of an infrared thermography camera and a conical mirror inside the reactor enables the measurement of catalyst surface temperature. The reactor operates under industrially relevant conditions and allows investigations at different feed temperatures and feed ratios at steady-state. The capabilities of the setup are demonstrated for CO$_2$ methanation on a cylindrical 5 mm Ni/γ-Al$_2$O$_3$ catalyst pellet. Pronounced intra-pellet CO$_2$ concentration gradients are observed despite a stoichiometric educt feed ratio, whereas H$_2$ exhibits only minor gradients throughout the pellet. ... mehrThe infrared camera measurements reveal a surface temperature increase of up to 25 K with pronounced gradients in flow direction. Apart from these axial gradients, the pellet surface temperature is uniform at steady state. The presented reactor provides detailed operando insights into coupled mass and heat transport phenomena at the single-pellet scale and could offer a robust basis of experimental data for future model validation and knowledge-based catalyst optimization.