Improved Apparatus for Dynamic Column Breakthrough Measurements Relevant to Direct Air Capture of CO₂

Dynamic column breakthrough (DCB) measurements are valuable for characterizing the adsorption of gaseous species by solid sorbents and are typically used for high concentrations of adsorptives, often at elevated temperatures and pressures. However, adsorbents for the direct capture of carbon dioxide from natural air demand measurement capability at low partial pressures of CO₂ at atmospherically relevant temperatures and pressures. We have developed a new apparatus focused on the measurement of DCB curves under typical tropospheric conditions. The new apparatus is described in detail and validated with breakthrough curve measurements. Adsorption capacities are reported at (233.1 to 323.1) K and (351 to 1078) hPa for low carbon dioxide concentrations on 13X zeolite samples on the order of a few hundred milligrams. Measurement uncertainties related to timing, flow, temperature, and concentrations are analyzed and the present results at 273 K, 298 K, and 323 K are compared with static measurements obtained with a manometric adsorption analyzer. In addition, experiments at a typical atmospheric CO₂ concentration of 400 microL · L^-1 have been performed.