The transport and distribution of reaction products above catalytically active Pt microstructures was studied by spatially resolved scanning mass spectrometry (SMS) in combination with Monte Carlo simulation and fluid dynamics calculations, using the oxidation of CO as test reaction. The spatial gas distribution above the Pt fields was measured via a thin quartz capillary connected to a mass spectrometer. Measurements were performed in two different pressure regimes, being characteristic for ballistic mass transfer and diffusion involving multiple collisions for the motion of CO(2) product molecules between the sample and the capillary tip, and using differently sized and shaped Pt microstructures. The tip height dependent lateral resolution of the SMS measurements as well as contributions from shadowing effects, due to the mass transport limitations between capillary tip and sample surface at close separations, were evaluated and analyzed. The data allow to define measurement and reaction conditions where effects induced by the capillary tip can be neglected ("minimal invasive measurements") and provide a basis for the evaluation of catalyst activities on microstructured model systems, e.g., for catalyst screening or studies of transport effects.

A two-step microreactor for the investigation of glucose oxidation is presented. A model is created to pre-judge the changes in concentrations of the reactants in the straight channels of the microreactor. The structure of the rapid mixingreaction units of the microreactor was optimized, and the optimal parameters were found to be p = 1:3, r = 1:1, and w s = 60 lm. The model and the optimization method can facilitate the design of microreactors.