Measurement and analysis of spatial reactor profiles in high temperature catalysis research

Spatial reactor profile measurements are a novel tool in chemical reaction engineering research. In this technique species concentrations or molar flow rates, phase temperatures and spectroscopic information are measured as function of the axial coordinate in a continuous flow tubular reactor. The obtained spatial gradients can be analyzed in terms of kinetic and mechanistic information about the reaction under study. The advantage of the spatial profile technique is that transient data are obtained at steady state and that it can be applied at temperature and pressure conditions relevant for industrial application. After a detailed description of the method various application examples are discussed such as methane catalytic partial oxidation on rhodium and platinum coated foam catalysts, methane oxidative coupling in the gas phase and oxidative dehydrogenation of ethane to ethylene on a supported molybdenum oxide catalyst. It is demonstrated how information about film transport limitation and reaction pathways can be extracted. The importance of spatial reactor profiles for validation of microkinetic models is highlighted for gas phase methane oxidative coupling at elevated pressure. Finally the idea of spatially resolved Raman spectroscopy using an optical fiber sensor is demonstrated and key parameters such as spatial resolution and position accuracy are determined.