Catalytic hybrid solvent regeneration in membrane vacuum processes for direct air capture

Direct Air Capture is a promising climate mitigation technology, but its deployment is limited by high energy demand. This study improves the energy efficiency and sustainability of liquid-based Direct Air Capture by integrating catalytic solvent regeneration and hybrid solvents with a low-temperature membrane vacuum regeneration process. Iron-sulfated zirconia catalysts supported on alumina and silica are synthesized and evaluated, with silica exhibiting superior catalytic performance. An optimal iron-sulfated zirconia to silica ratio of 1:1 reduces relative heat duty by up to 59.7% in the membrane vacuum system. To assess the impact of hybrid solvents on energy consumption, a solvent composed of 3 molar potassium taurinate and 1 molar potassium sarcosinate achieves a 69.1% improvement in CO2 desorption compared to potassium taurinate alone. Finally, combining the optimized hybrid solvent, catalyst, and membrane system at 90 °C reduces thermal energy consumption by 66.8% relative to potassium glycinate, achieving an energy requirement of 2.6 GJ/tCO2. Direct air capture (DAC) removes CO₂ from the atmosphere but remains energy-intensive at scale. Here, the authors integrate catalytic solvent regeneration and hybrid solvents with low-temperature membrane vacuum regeneration, significantly improving the energy efficiency and sustainability of liquid-based DAC systems.