Capturing CO₂ at the point by using TSA with electrically heated adsorbents
Carbon Capture and storage (CCS) and utilization (CCU) are considered as essential part for many industrial countries in the EU and beyond on the way to meet climate targets. Following this strategy involves CO2 capturing technologies that cause no or low greenhouse gas emissions themselves. As a technology for emission-free CO2-capture researchers from RWTH Aachen University, DWI — Leibniz-Institute for Interactive Materials, Aachen and University of Duisburg-Essen developed a resistively heated spiral wound module for temperature swing adsorption (TSA) [1].
CO2 capturing methods
In general, four different capture technologies are known for separating CO2 from fuel gases, other exhaust air streams or process streams. These are absorption, adsorption, membrane separation and cryogenic separation.
Explained in simple terms, absorption processes make use of liquids that absorb CO2 physically or chemically, in adsorption processes the ability of solvents to attach CO2 is used, and in membrane processes the gas separation either takes place due to different solubilities and diffusivities of gases in dense membranes or a porous, hydrophobic membrane serves as contact medium between the gas to be treated and a liquid absorbent (membrane contactor process). Cryogenic gas separation is the process of cooling a gas mixture to very low temperatures so that its components liquefy at different boiling points and can then be separated, typically by fractional distillation.
A more detailed overview of the CO2 separation technologies is given by Madejski et al., as an example [2].
Each technology comes in different variants, most systems do not have a technology readiness level suitable for commercial demonstration or normal commercial service, as Karayil et al. state in their study [3]. In this study they analysed the four technologiy options in terms of technologigal, social, geo-political, economic, and environmental aspects. For this they used the TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) method.
The data in the following table are taken from the study [2] and provide an overview of the currently achievable CO2 capture rates and energy consumption figures for the four technology variants.
| Type of Capture Technology | CO₂ capture rate | Overall Energy Consumption |
| Absorption | 60 — 95 % | 2.3 — 9.2 GJ/tCO2 |
| Adsorption | 80 — 95 % | 4 — 6 GJ/tCO2 |
| Membrane | 60 — 90 % | 0.5 — 6 GJ/tCO2 |
| Cryogenic | 85 — 99,99 % | 2.4 — 5.2 GJ/tCO2 |
Electrifying temperature swing adsorption
Coming back to the study carried out by Esch et al. [1], it should be mentioned that adsorption processes operate cyclically with alternating adsorption and desorption. Adsorption is facilitated by elevating the pressure or lowering the temperature, while desorption takes place at lower pressure or higher temperature.
For the case of temperature swing adsorption heating is normally carried out by purging the adsorber column with heated gas or steam. As this is generated by burning fossil fuel combustion in most cases, electrifying the heating process would offer the option to use emission-free electric energy.
Coming back to the study carried out by Esch et al. [1], it should be mentioned that adsorption processes operate cyclically with alternating adsorption and desorption. Adsorption is facilitated by elevating the pressure or lowering the temperature, while desorption takes place at lower pressure or higher temperature.
For the case of temperature swing adsorption heating is normally carried out by purging the adsorber column with heated gas or steam. As this is generated by burning fossil fuel combustion in most cases, electrifying the heating process would offer the option to use emission-free electric energy.
The researchers invented an adsorptive medium that can be heated resistively. As adsorbing medium a non-woven carbon fabric was impregnated with polyethyleneimine (PEI). This impregnated fabric was implied into a spiral-wound module, a design that is well-known for membrane applications.
The researchers analyzed the electrical conductivity and resisistive heating behaviour as well als the gravimetric CO2 adsorption and desorption behavior with samples of the impregnated carbon fabric.
The spiral wound module was tested with respect to its temperature behavior and CO2 capture efficiency under dynamic conditions. As test gas 15 % CO2 in N2 was used. Although the CO2 working capacity under dynamic flow conditions in the module was lower than with the flat adsorbing sheet, the authors of the study are optimistic to establish this type of module for emission-free gas separation processes at industrial scale. To achieve this target, further research will be carried out to identify und screen conductive subtrates with higher internal porosity and to use thinner, more uniform PEI coatings to facilitate CO2 uptake and mitigate diffusion limitations within the module.
References
[1] Esch, C.; Mehltretter, M.; Neese, J.; Herrmann, S.; Ryapushkin, R.; Linnartz, C.J.; Wessling, M. Resitively heated spiral wound module for temperature swing adsorption of CO2. Chemical Engineering Journal 524 (2025) 168727. https://doi.org/10.1016/j.cej.2025.168727https://doi.org/10.1016/j.cej.2025.168727.
[2] Madejski, P.; Chmiel, K.; Subramanian, N.; Ku´s, T. Methods and Techniques for CO2 Capture: Review of Potential Solutions and Applications in Modern Energy Technologies. Energies 2022, 15, 887. https://doi.org/10.3390/en15030887. [3] Karayil, A.; Elseragy, A.; A. M. Aliyu, A. M.: An Assessment of CO2 Capture Technologies towards Global Carbon Net Neutrality. Energies 2024, 17, 1460. https://doi.org/10.3390/en17061460.