Influence of Hydrodynamics on Yield and Selectivity in Reactive Bubbly Flows

The conversion of chemical substances with high selectivity and yield is one of the major tasks in Chemical Process Engineering. For the production processes of many bulk chemicals it is necessary to bring gaseous substances in contact with a continuous liquid phase (e.g. oxidation, hydration and chlorination). Despite their importance, multi-scale transport processes with a coupled reaction could not be adequately described so far. Often the assumed reaction rates are including an unknown part of mass transfer in addition to the intrinsic kinetics. Thus, the transferability of models and the predictive forecast of yield and selectivity are very limited. Up to now, there were neither experimental nor numerical tools with sufficiently high spatial and temporal resolution available to determine the uninfluenced reaction rates. The new possibilities for the elucidation of reaction networks and local transport processes as well as for the numerical simulation of gas-liquid interfaces are used in the DFG priority program “Reactive Bubbly Flows” specifically on the systematic analysis of complex technical processes. Therefore new chemical systems with adjustable reaction kinetics have been developed to investigate, how yield and selectivity in bubbly flows is influenced by mass transfer and mixing. New methods for setting defined mixing ratios (micro reactors, turbulence generators), new measurement equipment (e.g. Taylor-Flow Capillaries) and new analytical methods (e.g. Confocal Laserscanning Microscopy,  Resonance Raman) are used to identify the limiting transport phenomena. For the research program experimental and numerical methods are under development and applied to the analysis and calculation of reactive bubbly flows to allow a predictive forecast of yield and selectivity for chemical reactions overlaid with mass transfer limitations. In this presentation the German priority program will be introduced and first results will be presented.