Removal of CO₂ Capture Solvent Contaminants and Degradation Products Using Activated Carbon

Managing solvent contamination during postcombustion carbon capture is necessary to avoid or reduce potential adverse economic, environmental, and human-health impacts due to solvent degradation and rejuvenation processes. While elimination of these contaminants would be an ideal scenario, a more practical strategy involves solvent cleaning during operation. To assess the ability of activated carbon for solvent cleaning, seven different commercial activated carbons were selected and tested on a heavily degraded amine solvent from the University of Kentucky’s Field Pilot Carbon Capture unit. This assessment included a detailed contaminant analysis which showed some success in removal of common heat stable salts (HSS) and polymeric amine compounds from the solvent ranging from 10 and 30%, respectively, using coal-based activated carbons. The activated carbon treatment was also effective at removing corrosion metals including Fe, Ni, and Zn as well as flue contaminants Se and Pb. The leaching of several metals, including As, Cu, and V, from the activated carbon into the solvent was also observed, especially from the coal-based activated carbons. The activated carbon treatments showed some additional benefits in terms of reduction of the solvent viscosity by up to 30% and removal of upward of 50% of the aldehydes present. The results show that activated carbon treatments may be better suited in a multistep solvent management strategy rather than as a stand-alone treatment. Our proposal would be to use activated carbon treatments as part of a two-phase approach along with thermal reclaiming.