Gas Phase Oxidation of Monoethanolamine (MEA) with OH Radical and Ozone: Kinetics, Products, and Particles

Monoethanolamine (MEA) is currently the benchmark solvent in carbon capture and storage (CCS), a technology aimed at reducing CO₂ emissions in large combustion industries. To accurately assess the environmental impact of CCS, a sound understanding of the fate of MEA in the atmosphere is necessary. Relative and absolute rate kinetic experiments were conducted in a smog chamber using online proton transfer reaction mass spectrometry (PTR-MS) to follow the decay of MEA. The room temperature (295 ± 3K) kinetics of oxidation with hydroxyl radicals from light and dark sources yield an average value of (7.02 ± 0.46) × 10^–11 cm³ molec^–1 s^–1, in good agreement with previously published data. For the first time, the rate coefficient for MEA with ozone was measured: (1.09 ± 0.05) × 10^–18 cm³ molec^–1 s^–1. An investigation into the oxidation products was also conducted using online chemical ionization mass spectrometry (CI-TOFMS) where formamide, isocyanic acid as well as higher order products including cyclic amines were detected. Significant particle numbers and mass loadings were observed during the MEA oxidation experiments and accounted for over 15% of the fate of MEA-derived nitrogen