Ultra-violet Treatment as a Strategy for Destruction of Degradation Products from Amine Based Post Combustion CO2 Capture

The amine-based post-combustion capture (PCC) of CO2 is an option being considered for the reduction of anthropogenic CO2 emissions. PCC plants will be attached or retro-fitted to fossil-fuel fired power generating infrastructure (i.e. large stationary point sources) during the transition to renewable energy, which is expected to take place over several decades. Despite being an established technology widely used to remove CO2 from small scale-commercial process such as natural gas sweetening, there are many challenges that must be overcome before large scale implementation of the process can be realised. Some of these challenges include:•Reducing plant capital costs•Reducing the energy required for solvent regeneration/release of captured CO•Reducing solvent degradation in the presence of O2 and other flue gas contaminants, such as NOx and SOx,and•Reducing and understanding the environmental impact i.e. the potential of solvents and solvent degradation products to be released into the environment through off-gases, leaks or spills, and any associated impact this might have.Several recent research articles1-3 have highlighted the propensity of amine-based solvents to undergo certain chemical transformations, both in the condensed and aqueous phases, which produce harmful materials such as nitrosamines and nitramines. The formation and emission of nitrosated amines from the PCC process has not been fully investigated, although it is now the focus of some research agencies in Europe and Australasia. Nitrosamine formation mechanisms are presented in relation to the post- combustion capture of CO2 with aqueous amine solvents. The relative merits of nitrosamine mitigation strategies are also discussed. In particular the susceptibility of several nitrosamines to UV destruction is explored; the results are compared with TD-DFT results which predict excitation energies with good accuracy. The rate of destruction versus UV wavelength is also discussed, with a view to understanding which electronic transition facilitates decompositio