2024 AIChE Annual Meeting

(43a) Equilibrium and Kinetic Studies of CO2 and H2o Adsorption on Lewatit VP OC 1065 for Direct Air Capture: A Combination of Dynamic Column Breakthrough and Dynamic Vapor Sorption

Authors

Balasubramaniam, B. - Presenter, University of Alberta
Forbes, E., University of Alberta
Picard, C., University of Alberta
Sawada, J., University of Alberta
Rajendran, A., University of Alberta
In recent years, governments and private industries have shown immense interest in the large-scale implementation of direct air capture (DAC) technologies [1,2]. Adsorption-based DAC is preferred as it offers lower energy and higher productivity than alkali scrubbing [3]. There have been multiple modelling studies on using a temperature-vacuum swing adsorption (TVSA) process cycle for DAC [3-6]. However, these studies indicate that the absence of CO2/H2O binary equilibrium data and kinetics of CO2 and H2O sorption impedes reliable process evaluation of DAC sorbents [3, 6]. Measuring these key adsorption characteristics as part of an experimental campaign is the objective of our work.

Due to its commercial availability, the polymeric resin Lewatit VP OC 1065 has been chosen for this study. Single-component isotherms of CO2 and H2O were measured using static experiments. An in-house built micro-scale dynamic column breakthrough (DCB) system using a column with 100 mg of the sorbent was used for the study [7]. Single-component breakthrough experiments for CO2 and H2O at various flow rates, compositions, and temperatures were performed. The equilibrium loadings from the single-component DCB experiments are comparable to the static CO2 loadings with an error of +/- 0.1 mmol/g, establishing the accuracy of the breakthrough system. For binary CO2/H2O measurements, the DCB and dynamic vapour sorption (DVS) were used in tandem. The binary CO2 and H2O loadings were estimated using the DCB by an accurate closure of the mass balance. The kinetics of CO2/H2O sorption were measured in the DVS unit and were used to describe the breakthrough experiments. The binary sorption of CO2 and H2O on Lewatit is an interesting case of co-operative adsorption and hence produces adsorption breakthrough curves that are rarely seen in conventional physisorption systems. We observe that the CO2 loading in the presence of water is higher than the dry CO2 loading as expected from amine-functionalized sorbents. Finally, we fit a modified Toth model to the binary CO2 data collected and simulate a TVSA cycle using the detailed process model employing accurate values for CO2 and H2O equilibrium and kinetics [4,8]. We compare the process performance of Lewatit with and without binary CO2 data highlighting the importance of collecting binary data and kinetics on DAC sorbents. Our work also shows the potential of using small amounts of samples, which would prove beneficial for the characterization of future DAC sorbents.

References:

1. U. S. Department of Energy (DOE), “https://www.energy.gov/articles/biden-harris-administration-announces-12-billion-nations-first-direct-air-capture”, 2023

2. IPCC, “Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II and III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change”, 2023

3. F. Sabatino et al., Joule, vol. 5, pp. 2047–2076, 2021

4. V. Stampi-Bombelli et al., Adsorption., vol. 26, pp. 1183–1197, 2020

5. J. Young et al., Energy Environ. Sci., vol. 14, pp. 5377–5394, 2021

6. B. M. Balasubramaniam et al., Chem. Eng. J., vol. 485, 149568, 2024

7. N. S. Wilkins et al., Ind. Eng. Chem. Res., vol. 61, pp. 7032-7051, 2022

8. R. Haghpanah et al., Ind. Eng. Chem. Res., vol. 52, pp. 4249–4265, 2013