In contrast, a membrane microstructure reactor through which suspension flows has advantages in terms of reaction technology. It uses membranes for bubble-free gas dosing along the reactor while the catalyst is suspended in the liquid educt or solvent and transported through microchannels:
Scalability. Since there are no free gas bubbles in the flowing suspension and the solids content is low, the distribution of the feed to many parallel channels is less demanding in higher throughput systems.
Enhanced mass transfer. The meandering shape of the channels induces a movement of the catalyst particles transverse to the main flow. This improves the mass transport of the gas from the wall into the core flow and between the core flow and the particles. At the same time, the deposition of particles at the channel bottom is prevented.
Flexibility. It is possible to use the same reactor system for different catalysts/applications. The catalyst can be ejected and regenerated if necessary, and several gases can be fed separately into different areas, creating an additional degree of freedom that can be used to generate specific concentration profiles.
|Fig. 1: Scheme of the membrane reactor through which a catalyst suspension flowing through it. It is suitable for general multiphase reactions in which two gaseous reactants are contacted over a catalyst in the liquid phase and in particular for direct synthesis of hydrogen peroxide (reactants H2, O2).|
The advantages of the concept go hand in hand with the multitude of new degrees of freedom in reaction technology. Accordingly, there are still many basics unexplored as to how such systems can be optimally operated. Within the subproject "Multiphase Catalysis", an understanding of the local transport and reaction phenomena will be developed using the example of hydrogen peroxide direct synthesis by means of novel miniaturized electrochemical and electrical sensors. In addition, location- and time-resolved computer simulations form the basis for a comprehensive qualitative and quantitative understanding of the process.