(320a) Intensified Direct Air Capture Process Using Aqueous Amino Acid Solvents with Low Regeneration Temperature

Aqueous amino acids, such as potassium sarcosinate (K-SAR), have emerged as high-performance direct air capture (DAC) solvents due to their low volatility, high CO₂ capacity, rapid CO₂ uptake kinetics, low-temperature and energy of regeneration requirements at 110 °C, and because they are environmentally friendly solvents. Our study focuses on enhancing DAC efficiency through an intensified process employing a high-flux air-liquid contactor, catalytic regeneration and sub-ambient solvent formulation to improve DAC plant economics. We developed a low-cost, corrosion-resistant high-flux DAC (HiDAC) contactor exhibiting excellent compatibility with K-SAR, showcasing remarkable CO₂ capture rates and efficiencies within a compact configuration. Subsequently, catalytic regeneration was adopted to reduce the energy burden of solvent regeneration. A TiO₂ solid catalyst demonstrated significant improvements in CO₂ desorption rates and cumulative CO₂ removal at lower regeneration temperatures, leading to a substantial reduction in the overall regeneration energy requirements due to reductions in the sensible and vaporization heats. To address potential sub-freezing DAC conditions, we applied anti-freezing solvent formulations and investigated the performance of K-SAR at sub-freezing temperatures. We explored the efficacy of ethylene glycol additives in preventing solvent freezing, revealing promising CO₂ fluxes across a wide temperature range. Finally, our study offers a comprehensive technoeconomic analysis of these intensified DAC approaches, providing insights into their feasibility and potential for widespread adoption. By integrating advanced materials and innovative processes, we aim to contribute to the development of more sustainable and cost-effective DAC solutions, crucial for combating climate change.