(381e) Methods for Characterizing Sorbents for Direct Air Capture and Post-Combustion Carbon Capture

There is currently great interest in the development of carbon capture technology, with adsorption by porous materials being one of the main methods under serious consideration. Carbon capture involves the removal of CO₂ from a gas mixture, with the details defined by the specific carbon capture method. Direct air capture (DAC) is the removal of CO₂ from atmospheric air and therefore requires CO₂ adsorption at low concentrations, around 400 ppm, from a complex gas mixture (air) at ambient pressure. Post-combustion carbon capture, meanwhile, is the removal of CO₂ from point sources, typically fossil fuel power plants. In this case, CO₂ must be adsorbed from a flue gas, consisting mainly of N₂, with varying levels of other minor contaminants, and CO₂ at an approximate concentration of 15%. CO₂ adsorption from an 85/15 mixture of N₂/CO₂ at ambient pressure has therefore become the standard under which sorbents for post-combustion carbon capture are typically studied. Recent work has identified significant gaps in the data on adsorbent properties required for process modelling and design in the case of DAC [1], but there are also more general challenges associated with characterizing adsorbents for gas separations, which apply to both DAC and post-combustion carbon capture [2]. Characterizing adsorbents for DAC is complicated by the presence of water in atmospheric air and the resultant competitive adsorption between H₂O and CO₂. In this poster, we consider the relative merits of various adsorption measurement methods for characterizing sorbents for DAC and post-combustion carbon capture, and present example data on some representative materials.

References

[1] M.-Y. Low, L. V. Barton, R. Pini & C. Petit, 2023, Analytical review of the current state of knowledge of adsorption materials and processes for direct air capture, Chem. Eng. Res. Design 189, 745-767

[2] D. P. Broom, 2023, Characterizing adsorbents for gas storage and separation, Adsorption DOI:10.1007/s10450-023-00424-9