Steam adsorption equilibrium data at 110°C on an activated carbon, Lewatit VP OC 1065, and CALF-20 using a microscale dynamic column breakthrough apparatus

Steam adsorption equilibrium data is important for many carbon capture applications, including direct-air capture, point-source, and pre-combustion carbon capture. However, there is a dearth of concentrated unary equilibrium data for H2O at temperatures greater than 100°C. In this study, unary steam adsorption equilibrium data was measured at 110°C and up to approximately 1.0 bar partial pressure with a steam microscale dynamic column breakthrough (μDCB) apparatus using a milligram quantities of adsorbent. These partial pressures are equivalent to those used in industrial carbon capture processes. The construction of the apparatus is detailed, along with the necessary calibrations and validations to ensure accurate equilibrium measurement. 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). It was observed that steam adsorbs strongly on all three materials at 110°C. 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 the cubic-Langmuir isotherm. The 110°C data was compared against H2O equilibrium data collected at 25°C as a function of relative pressure. An in-house dynamic column breakthrough simulator coded in MATLAB was able to predict the μDCB composition breakthrough curves well for all three materials. The data obtained from the steam breakthrough experiments has important process implications and highlights the need to measure steam adsorption data for any proposed carbon capture material.