An overview of the materials and methodologies for CO₂ capture under humid conditions

Abstract

CO₂ capture is one of the cardinal technologies to combat the ever-escalating CO₂ concentration in the atmosphere and to address the global climate change. Among the several strategies employed, adsorption on a porous solid seems to be a promising alternative to conventional CO₂ capture technologies. However, to employ this technology under real-world CO₂ capture conditions, the stability of the adsorbent materials under humid conditions is of paramount importance. To date, several CO₂ sorbent materials have been reported to show remarkable CO₂ uptake capacities both by physical and chemical adsorption. Nevertheless, the stability of many of these superior adsorbents under humid conditions is questionable. This is a key issue that hinders their commercial exploration under real flue gas conditions. The systematic tuning of material properties such as porosity, wettability, and hydrophobicity and functionalization strategies can play a decisive role in enhancing the material stability and CO₂ sorption capacity. Herein, we present a comprehensive review of the trends and innovations in CO₂ capture under humid conditions. Various materials and methodologies employed for CO₂ capture from a humid stream are extensively reviewed. In particular, some of the key strategies such as tuning the hydrophobicity, amine modifications, introduction of polar functional groups, and water enhanced CO₂ uptake are discussed in detail. We believe that the present review can lead this emerging field to develop state-of-the-art materials that can have a potential future in real-world CO₂ capture technologies.