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This contribution presents the results of continued investigations on the production of hydrogen by means of pyrolysis in a liquid metal bubble column reactor, as developed at the Karlsruhe Institute of Technology in recent years. Part I of this contribution described the motivation and the methodology of this study, as well as a significant scale-up, and discussed its results for pure methane pyrolysis. Here in part II, two additional experimental campaigns with methane–ethane mixtures (MEMs) and high-calorific natural gas (nGH) will be presented and discussed for the first time, using the up-scaled liquid metal bubble column reactor. It could be proven that an MEM as the feed gas led to an increase in methane conversion at low temperatures, which is consistent with the literature data. The nGH pyrolysis confirms this trend and also results in a significant rise in methane conversion compared to pure methane pyrolysis. Furthermore, the nGH pyrolysis leads to an increased methane conversion even at higher temperatures compared to MEM pyrolysis. Additionally, both MEM and nGH pyrolysis also showed a shift in the formation of by-products toward lower temperatures.

Angewandte Chemie / International edition e202218850 (2023). doi:10.1002/anie.202218850 special issue: "Hot Topic: Water Splitting", Published by Wiley-VCH, Weinheim

This work investigates a direct transfer of dispersed particles into another dispersion medium. The transfer is realized by layering the suspension above a second, non-miscible liquid. The particles are then transferred by centrifugation or mere sedimentation. The transfer is, unlike a liquid-liquid extraction, not only driven by thermodynamic effects such as favorable solubility, but is based on an additional mechanical work input. Here the transfer of a colloidal particle system is discussed on the example of SiO2 particle dispersions with regards to the influence of particle size, viscosity, density and an emphasis on the effects of interfacial forces. For small particles it was found that hydrophilic and hydrophobic forces dominate and hinder the transfer as particles adsorb to the interface, which can be countered by an increase of centrifugation forces or reduction of surface forces with surfactants. The transfer is described in detail with a model to lay out the influence of all parameters, revealing a threshold size for a successful transfer at given conditions. The model is applied and tested on different SiO2 suspensions for verification.