Investigations on the co-adsorption behaviour of humid gas mixtures

• Applicant: Dr.-Ing. Carsten Wedler
• Subject Area: Technical Thermodynamics
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 497236263

In order to capture CO2 from, e.g., industrial exhaust gas streams or directly from ambient air, adsorption processes are used to separate CO2 from gas mixtures in many climate change relevant applications such as direct air capture (DAC) or carbon capture and storage (CCS). In most cases, gas mixtures, such as CO2-rich exhaust gas from power plants, contain water vapour, which has a considerable influence on the adsorption properties of the other gas components. Therefore, the design of adsorption processes requires detailed investigations on the occurring co-adsorption mechanism for the selected adsorbent-gas mixture system. However, experimental investigations on co-adsorption are not trivial, whereby investigations with dry gas mixtures are still considerably easier to implement than with humid gas mixtures. Therefore, in many experimental investigations, the water vapour is omitted, which results in the experimental data having considerable uncertainty. So far, various methods for measuring the co-adsorption of humid gas mixtures have been described in the scientific literature, but none of them has yet been established as a standard method. Since the measurements are demanding, the experimental database in the literature on the co-adsorption of humid gas mixtures is insufficient. Therefore, the first objective of this project is to develop and establish a standard method, which is based on the gravimetric adsorption measurement method and enables the investigation of the co-adsorption of humid gas mixtures with different and reproducible water vapour contents. This method will be used to investigate adsorption equilibria of binary, ternary, and quaternary humid gas mixtures on two differently structured adsorbents. The resulting data will be used to model the adsorption equilibria. Two models for humid gas mixtures known from the literature will be applied, but it is known that they do not consider interactions between the different gas molecules. Therefore, this project will also investigate whether a more complex model for humid gas mixtures can be adapted, which is based on the lattice density functional theory.

• DFG Programme: WBP Fellowship
• International Connection: United Kingdom
• Host: Dr. Ronny Pini