Key factors influencing direct CO2 capture from air

Abstract

Excessive CO2 emission into the atmosphere has caused serious climate change that draws global concerns. Direct air capture (DAC) plays a crucial role in reducing atmospheric CO2 concentration and mitigating climate change. In this review, we summarize the latest advances and emerging opportunities in DAC through three key aspects. First, we introduce two different types of air contactors (adsorption- and absorption-based) and their functions, unveiling their critical roles in DAC. Second, we discuss a number of effective capture agents for DAC, including solid adsorbent materials and liquid absorbent solutions, with emphasis on the capture mechanism and efficiency. Third, we present three typical methods for CO2 release and capture agent regeneration that match DAC effectively, including temperature swing, precipitation-phase separation, and electrolysis, focusing on the CO2 release process and energy consumption. In the end, we provide insights into the existing challenges, potential solutions, and future directions for advancing DAC technologies. Keywords: CO2 capture; Direct air capture; Air contactor; Capture agent; Regeneration method.