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Performance Metrics for Direct Air Capture of Carbon Dioxide


For the Direct Air Capture (DAC) of CO2 from the atmosphere it is important to know how well the materials will perform as sorbents. Current material characterization includes isothermal adsorption measurements, but such information is insufficient to determine the performance. This work aims to define performance metrics based on intrinsic material properties to enable accurate and informative high-throughput screening of materials for use in DAC.


Gray lines connect to form a complex three-dimensional network of shapes with red spheres between them.

A conceptual illustration of a porous crystalline material. The red spheres represent voids where CO2 might collect.

Credit: NIST

Sorbents in Direct Air Capture (DAC) are exposed to the atmosphere, where they adsorb CO2 then are isolated from atmosphere, the CO2 is driven off by heating or pulling vacuum, refreshing the sorbents. This adsorption-refresh cycle depends not only on the competitive adsorption of CO2 with the other atmospheric constituents, but also depends on other material properties such as the specific heat. The performance metrics developed in this work integrate all of these material properties to calculate an idealized performance of the material in a DAC process.

These performance metrics provide critical insight to DAC process engineers for designing DAC facilities, and for selecting materials for use as sorbents in DAC.

Created May 9, 2023