Amine-based sorbents for CO2 capture from air and flue gas-a short review and perspective

摘要

This review briefly examines the current state of amine-based and polymer sorbents as well as highlights the structure of strongly and weakly adsorbed CO2 intermediates on amine-based sorbents and their roles in thermal swing adsorption (TSA) and vacuum swing adsorption (VSA) CO2 capture process. Weakly adsorbed CO2 sites on amine sorbent allow amine sorbents to be regenerated by vacuum evacuation at ambient temperature (i.e., VSA) while strongly adsorbed CO2 sites must be regenerated by heating the sorbent (i.e., TSA). This perspective discusses key issues regarding thermal swing and pressure/vacuum sorbents for CO2 capture, the mechanism of CO2 adsorption on amine sorbents, and the methodology for sorbent development. The perspective also provides a direction for further improving amine sorbents and processes for CO2 capture and suggests that amino-porous and polymer sorbents operated in a vacuum-assisted thermal swing (V/TSA) mode could lead to a cost-effective CO2 capture process. To facilitate the development of effective amine sorbent CO2 capture processes, the design and fabrication of porous sorbents should be considered at various length scales: (i) the structure of amine sites and their neighboring functional groups at a nanometer scale in the sorbent particle to reduce the CO2 binding energy on amine sites, (ii) incorporation of the amine sorbent particles into the internal structure of the adsorber at a centimeter and meter scale, (iii) the mode of the adsorber operation, (TSA/PSA/VSA/TVSA), and (iv) the composition of the CO2-containing feed stream.Mitigating CO2-induced global climate changes calls for cost-effective approaches for capturing CO2. This short review unravels the current limitations of amine-based sorbent and porous polymer for CO2 capture. The perspective offers several thoughts and approaches to address the scientific/technical issues at each level from nanometer to meter scale in the development of sorbent and polymer-based CO2 capture process.