Process modelling of Direct Air Capture (DAC) of CO2 using solid amine sorbents

This paper presents a fixed bed reactor system to capture CO2 from ambient air via Temperature Vacuum Swing Adsorption (TVSA) cycles employing Lewatit® VP OC 1065 amine-functionalized adsorbents. Firstly, a model describing CO2 mixture flow, mass, and heat transfer with adsorption isotherm model is developed in Aspen Adsorption environment to study the performance of DAC processes with TVSA. Then, a single adsorption column is simulated to study both adsorption and breakthrough curves, and the model is validated with literature results. Secondly, a full DAC model with TVSA cycle is developed and the results are compared to TVSA cycle with a steam purge in literature to validate the reliability and simulation capabilities of the software tool. Lastly, a model of a process capturing 1.1 kilograms of CO2 per day is developed as a base case, and studies on the energy requirements, capital, and operating costs of the DAC system are conducted. In addition, sensitivity studies on the model parameters are carried out. This work stands as one of the first identified modelling studies of TVSA-based Direct Air Capture and serves as a basis to analyze the feasibility of DAC system deployment and its relevance in comparison to CO2 capture from point sources.