Assessment of a Direct Air Capture Process Scale-Up

This article presents a novel DAC process based on a solid sorbent material, in a continuous cycle of adsorption and regeneration. The silica-based sorbent is functionalized to provide a large specific area on a small volume, which allows to fix the CO2 molecules present in the treated gas quickly and efficiently. By modifying the surrounding pressure and temperature conditions of the material in a low vacuum steam stripping process, the captured CO2 is then released in concentrated form. The captured CO2 can then be utilized or sequestered, as the regenerated material can be reused for other adsorption and regeneration cycles. The article uses results from laboratory experiments performed at the gram scale of captured CO2 to examine system scale-up to the kilogram scale, for a fixed-bed reactor design. The reactor design was chosen for its mechanical simplicity, its inherent plug flow, allowing for high sorbent working capacity, and its absence of particle attrition [5]. Scale-up effects, such as adsorption and regeneration capacities, adsorption and regeneration kinetics and cycling effects on both effective quantity of captured CO2 and material degradation, are evaluated and presented. The analysis demonstrates the effect of the scale-up on global process performance in both adsorption and regeneration. It allows for the creation of a case study and mitigates the risks going forward with a bigger scale.