DBN-based molecular solvents for highly efficient and reversible CO2 capture

Abstract

Reducing greenhouse gas emissions is a crucial step in mitigating global warming. Carbon dioxide (CO2) represents one of the most pivotal greenhouse gases contributing to climate change. Many researchers are actively engaged in the development of effective and reversible CO2 absorbents to control and reduce CO2 gas emissions. In this paper, we synthesized a series of molecular solvents (MSs) based on the superbase 1,5-diazabicyclo [4.3.0]-5-nonene (DBN) and used them for CO2 capture. The CO2 capture capacity of MSs composed of DBN and different alcohols was systematically investigated, with DBN-Methanol (1:1.25) demonstrating superior absorption performance by achieving a maximum absorption capacity of 0.263 g CO2/g MS. The effects of temperature, pressure, the molar ratio of the hydrogen bond acceptor (HBA) to hydrogen bond donor (HBD), and moisture on the absorption process were studied. The experimental results were corroborated by NMR spectra analysis and FTIR spectra analysis, confirming that these MSs can effectively react with CO2 to produce carbonate and carbamate compounds through synergistic absorption involving hydroxyl group as primary component and amino group as secondary component. In addition, it is worth noting that the MSs studied in this work exhibit only glass transition at low temperatures and transform into ionic liquids (ILs) after capturing CO2, resulting in a significant increase in conductivity and demonstrating considerable electrochemical potential.