(589c) A Micro-Scale Breakthrough Apparatus for Measurement of Steam Adsorption on CO2 Capture Sorbents

Steam is an important component or purging gas for many carbon capture applications, including direct-air capture, post-, and pre-combustion carbon capture. However, essentially no concentrated (> 5 kPa,a) unary equilibrium data for H₂O exists at temperatures greater than 100^oC. This is in part due to the difficulty of the measurement. In this study, unary steam adsorption equilibrium data were measured at 110^oC up to approximately 1.0 bar partial pressure with a novel steam microscale dynamic column breakthrough (µDCB) apparatus on milligram-scale quantities of adsorbents [1]. The construction of the apparatus is detailed, along with necessary calibrations and validations, to ensure accurate equilibrium measurement. The milligram scale of the apparatus allows for rapid equilibrium measurements. Three adsorbents were considered in this study: an activated carbon (Calgon BPL), an amine-functionalized polymer (Lewatit VP OC 1065), and a metal-organic framework (CALF-20). These three adsorbents all have carbon capture applications involving the adsorption of steam. It was observed that steam adsorbs strongly on all three materials at 110^oC at 1.0 bar partial pressure. The mass balances for adsorption and desorption breakthrough experiments were solved for each experiment, and the loadings agreed well. This suggests that hysteresis is minimal at 110^oC. Activated carbon and Lewatit displayed type-3 isotherm shapes, and CALF-20 displayed a type-5 isotherm shape. Activated carbon and Lewatit were modeled with the GAB isotherm, and CALF-20 was modeled with an appropriate type-5 isotherm. A dynamic column breakthrough simulator was able to predict the µDCB composition breakthrough curves well. Since the experiments were performed under concentrated conditions, interesting adsorption and desorption curves were observed due to the change in effluent flow. These simulations provided appropriate mass and heat transfer parameters for large-scale simulation.

References:

Wilkins, N. S., J. A. Sawada, and Rajendran, A. Ind. Eng. Chem. Res. 61.20 (2022): 7032-7051.