Project abstract

Due to the high ratio of heat transfer surface to reaction volume in structured apparatus, not only optimum heat dissipation from the FT synthesis can be guaranteed, but also a relatively fast change of the reactor temperature can be achieved. In this way, it is conceivable that fluctuations in volume flow and composition can be compensated for by different material flows of CO2 (source-dependent fluctuation) and H2 (electricity fluctuation in electrolysis) and thus in the synthesis gas feed used (assumed to be reverse water gas conversion). For example, complete hydrogen consumption must be avoided in order to prevent coking of the catalyst. Due to the high space-time yield and the very short residence time in the microstructured reactors, it can also be expected that changing boundary conditions on the catalyst will be reflected more strongly in the product composition.

As part of the Helmholtz research, a continuous process line consisting of reverse water gas conversion, FT synthesis and hydrocracking with a total throughput of 20 l/min was built up. The relatively high throughput for the laboratory allows at least a minute-by-minute sampling of liquid products, which is necessary for dynamic experiments for the FT stage. For this purpose, the plant components are designed to be individually operable. Due to the complexity of the material composition of the products from the FT synthesis, basic considerations for sampling and the analytical method were first discussed in order to avoid longer dead times between reactor and sampling and to acquire important parameters of the material composition quickly. In addition to experimental investigations with dynamically changing substance compositions, flow and temperature, accompanying simulations of the reactor and the transport processes as well as catalysis are carried out in order to facilitate the interpretation of the experimental results. Special attention is also paid to the interaction of parameter variation and catalyst deactivation in order to develop suitable control strategies or catalyst alternatives to avoid deactivation. A cooperation with in-operando spectroscopy on the catalysts used with the help of synchrotron radiation has been established at KIT in cooperation with the Grunwaldt working group to investigate the causes of deactivation.