Direct Air Carbon Capture and Recovery Utilizing Alkaline Solution Circulation

Abstract

Direct air capture (DAC) represents a promising technology for mitigating climate change by extracting CO2 from the atmosphere. This study introduces a novel application for effective CO2 capture from dispersed emission sources, integrated with a liquid electrolysis system to improve capture cycle efficiency. By focusing on distributed sources, the DAC application overcomes the constraints of traditional stationary CO2 capture methods. It employs a thin-layer moving bed spray and air convection to capture CO2 in lean liquid, which converts into rich trap liquid when the carbonate concentration exceeds a certain threshold. Electrolysis is then used to recover the lean liquid. This design allows for quick, energy-efficient CO2 absorption even under low partial pressure conditions (462 ppm). The technology is designed to facilitate significant CO2 capture while concurrently generating high-purity hydrogen and collecting carbon dioxide. By reusing the capture liquid, an integrated capture and desorption process is realized. In a test with 1 M KOH as a lean trap solution and a wind speed of 9 m/s, a rich trap solution was obtained after 13 h, lowering the CO2 concentration at the outlet by 97 ppm compared to the input air, demonstrating the device’s effectiveness.