A UHV-Compatible Flow Reactor for Model Catalytic Reactions under Realistic Conditions Combined with Catalyst Cluster Synthesis

The study of model catalysts under complex reaction conditions needs to address several challenges, including high-sensitivity detection, accurate control of reaction pressure and temperature, while ensuring a contamination-free environment. Here, we developed a UHV-compatible flow reactor designed to investigate model catalytic reactions. The reactor is integrated into an existing ultra-high vacuum (UHV) system, which facilitates the synthesis of mass-selected clusters and their controlled deposition on model substrates. The combination of the flow reactor with the preparation system enables catalyst preparation, characterization, and testing without exposure to ambient conditions. The reaction cell features a dual-cup design with a reaction volume of less than 3 ml and is equipped with a near-infrared (NIR) laser heater and a quadrupole mass spectrometer (QMS) for continuous product analysis. The gas handling unit allows for the use of different gas mixtures flowing at various pressures through the reaction cell. The laser heating unit provides precise temperature regulation through programmable heating and cooling profiles. As a proof of concept, catalytic CO oxidation was studied on a Pt(110) single crystal and CeO₂-supported, mass-selected Pt2₀₀ clusters. The results demonstrate distinct reactivity trends, activation temperatures, and hysteresis behavior, highlighting the reactor's functionality for detailed studies in model heterogeneous catalysis.