(537b) Process-Characterization of Lewatit VP OC 1065 for Direct Air Capture (DAC) of CO2

With the recent IPCC report and the investment of the United States towards programs aiming at large-scale CO₂ removal from the atmosphere, it is clear that negative emission technologies like Direct Air Capture (DAC) are necessary to meet the 2050 net-zero goals [1,2]. Sabatino et al. concluded that solid sorbents provide better process performance than amine/alkali scrubbing for DAC, although with significant uncertainties [3]. The uncertainties stem from the dearth of information about the CO₂ adsorption kinetics (k_CO2), H₂O equilibria, and binary CO₂-H₂O isotherms on the DAC sorbent. With the availability of this information, process models can be developed to evaluate solid sorbents.

We have chosen the commercially available Lewatit VP OC 1065 as the DAC sorbent for this study. Single-component CO₂ and H₂O equilibrium isotherms at different temperatures were obtained through volumetric measurements. Dynamic column breakthrough (DCB) experiments were performed to estimate k_CO2 at various compositions relevant to DAC. k_CO2 at higher temperatures, i.e., T=120-150°C is necessary since temperature swing adsorption (TSA) cycles are considered for DAC. The DCB experiments were performed under dry simulated air, i.e., 0.04% CO₂ and rest N₂ at T=30°C. The breakthrough curves were fit to a linear driving force (LDF) model to estimate k_CO2. Binary breakthrough experiments with H₂O and CO₂ have been performed and the responses simulated using a dynamic model. A simple adsorption-desorption TSA cycle has been implemented experimentally and modelled using a detailed process model. These experiments provided a basis for validating the models and estimating the energy requirements of a process.

References:

1. IPCC, Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change., 2021

2. U.S.DoE., https://www.energy.gov/articles/biden-administration-launches-35-billion...
3. F. Sabatino, A. Grimm, F. Gallucci, M. van Sint Annaland, G. J. Kramer, and M. Gazzani, “A comparative energy and costs assessment and optimization for direct air capture technologies,” Joule, vol. 5, pp. 2047–2076, 2021