Parameter Optimization of the Direct Air Capture (DAC) Process to Achieve Net Zero Emission Targets

Direct Air Capture (DAC) technology has gained recognition as an effective method for reducing atmospheric carbon dioxide (CO₂) levels. This study emphasizes the optimization of critical process parameters to improve the efficiency of aqueous hydroxide-based DAC systems while lowering operational costs. Aspen Plus simulations were employed to model the process flow, pinpoint key reaction mechanisms, and evaluate how different operating conditions influence CO₂ capture efficiency. A sensitivity analysis explored the impact of variables such as air contactor parameters, solvent concentration, temperature, pressure, and moisture content on system performance. The results demonstrated that adjusting the Ca (OH)₂ flow rate to 760 t.h-1 achieves a 75% CO₂ capture rate at the air contactor, while maintaining an inlet air pressure of 1.1 atm enhances absorption. The CO2 capture rate increased gradually with the increase of inlet air temperature. The highest CO2 capture rate of 92% is given at 40°C, and 4% H2O content is in the inlet air. However, the impact of the moisture content is negligible. Furthermore, structured packing materials like BX packing outperformed Mellapak 250Y and Mellapak 350Y in efficiency. These insights support the development of economical DAC strategies, advancing technologies for carbon removal to achieve net-zero emissions.