Sorption direct air capture with CO2 utilization

Abstract

Direct air capture (DAC) is gathering momentum since it has vast potential and high flexibility to collect CO₂ from discrete sources as “synthetic tree” when compared with current CO₂ capture technologies, e.g., amine based post-combustion capture. It is considered as one of the emerging carbon capture technologies in recent decades and remains in a prototype investigation stage with many technical challenges to be overcome. The objective of this paper is to comprehensively discuss the state-of-the-art of DAC and CO₂ utilization, note unresolved technology bottlenecks, and give investigation perspectives for commercial large-scale applications. Firstly, characteristics of physical and chemical sorbents are evaluated. Then, the representative capture processes, e.g., pressure swing adsorption, temperature swing adsorption and other ongoing absorption chemical loops, are described and compared. Methods of CO₂ conversion including synthesis of fuels and chemicals as well as biological utilization are reviewed. Finally, techno-economic analysis and life cycle assessment for DAC application are summarized. Based on research achievements, future challenges of DAC and CO₂ conversion are presented, which include providing synthesis guidelines for obtaining sorbents with the desired characteristics, uncovering the mechanisms for different working processes and establishing evaluation criteria in terms of technical and economic aspects.