The buffered chemostat with non-monotonic response functions

We study how a particular spatial structure with a buffer impacts the number of equilibria and their stability in the chemostat model. We show that the occurrence of a buffer can allow a species to persist or on the opposite to go extinct, depending on the characteristics of the buffer. For non-monotonic response functions, we characterize the buffered configurations that make the chemostat dynamics globally asymptotically stable, while this is not possible with single, serial or parallel vessels of the same total volume and input flow. These results are illustrated with the Haldane kinetic function.Comment: 9th IFAC Symposium on Nonlinear Control Systems (NOLCOS 2013), Toulouse : France (2013

Development of porous material dual-functional reactors for the facile synthesis of sustainable chemicals

In this thesis, the task to improve reactions that are already established or on the brink of commercialization is tackled in three different ways with the help of porous materials to develop dual-functional reactor systems, that improve not only the synthesis reaction itself, like the reaction rate or the selectivity, but also serve a secondary purpose as they improve product separation and longevity or are simultaneously used for waste removal. The first reaction discussed is the methylamine synthesis from methanol and ammonia at high temperatures. The addition of a highly hydrophilic, water removing Na-LTA zeolite membrane led to increased methylation rates in the product distribution. By choosing a size selective catalyst a high selectivity towards the desired product dimethylamine could be achieved, while the extraction of the by-product water pre-emptively decreased the need for post-synthesis product separation. With post-synthesis ion exchange, K-LTA membranes where achieved to further improve the methanol conversion rate. The methanol-to-olefins (MTO) reaction is a promising alternative for small olefin production. By applying the aforementioned Na-LTA to the MTO reaction, the varying product composition could be stabilized over a long period of time, while also providing product separation and an enhanced catalyst longevity. Besides the dualfunctional production/separation reactors, production/decomposition experiments were conducted with the utilization of the (dotted variant) porous monolayer carbon graphene, the durability of the important cocatalyst Cu0 in TiO2 photocatalysis was achieved and improved the yield of hydrogen in photochemical water splitting and facilitated the con-current decomposition of the pollutant 2-chlorophenol