Catalytic Membrane Vacuum Regeneration: Enhancing Energy Efficiency and Renewable Compatibility in Direct Air Capture

Abstract

Liquid-based CO2 direct air capture (DAC) is a pivotal technology for mitigating climate change. Energy-intensive CO2 desorption, high regeneration temperatures, and solvent degradation are key challenges. Here, low-temperature catalytic membrane vacuum regeneration (C-MVR) as a promising approach for sustainable and energy-efficient DAC is developed and evaluated. Noncatalytic experiments are conducted using three commercial membrane modules and four green amino acid salts under varying conditions (e.g., temperatures and flowrates). Based on CO2 transfer rates, ultra-thin dense composite membranes and aqueous potassium taurinate (TauK) are the most promising for MVR in DAC applications. For C-MVR trials, commercial ion-exchange resin improves CO2 desorption fluxes by up to 64.4% and reduces thermal energy requirements by up to 39.1%. TauK demonstrates the highest CO2 flux and lowest thermal energy consumption. Parametric analysis of catalyst performance for varying temperatures, catalyst amount, and solvent concentrations is also performed. To minimize any potential precipitation in TauK, potassium carbonate (K2CO3) is added, showing minimal impact on CO2 desorption kinetics and catalyst improvement. The findings of this study highlight the practical applicability of C-MVR using green amino acid salts as a sustainable approach to boost CO2 desorption rate and reduce thermal energy input.