A Recirculating Reactor for Steady-State Kinetic Measurements: Design, Construction, and Testing with CO Oxidation over Pt(111) and Graphene/Pt(111)

We present the design and validation of a recirculating loop reactor that enables steady-state kinetic measurements for heterogeneous catalysis. This reactor is particularly suited for thin films and low surface area catalysts, which are not effectively evaluated in traditional flow reactors. Key improvements over previous recirculating reactors, such as direct heating of the sample with a focused IR lamp and temperature measurement in direct contact with the sample, allow for enhanced sensitivity and better kinetic analysis on samples with a low number of active sites or slow reaction rates. The system incorporates a bypass flow cell, to directly compare reactions on related powder catalysts under similar conditions with a standard plug-flow reactor. We demonstrate the reactor's capabilities by conducting CO oxidation experiments on a Pt(111) single crystal and a passivated, graphene-covered, Pt(111) crystal, highlighting the system’s ability to differentiate catalytic activity measurements in these model systems and compare them with high surface area powder catalysts of similar composition.