The effect of biomass ashes and potassium salts on MEA degradation for BECCS

This study investigates the comparative impact of inherently different biomass and coal ashes on the laboratory and pilot scale degradation of 30 wt% aqueous monoethanolamine (MEA), relevant to post-combustion CO ₂ capture. Thermal and oxidative degradation experiments were carried out at 135 °C and 40 °C respectively with CO ₂ loading (0.5 mol _CO2/mol _MEA), with and without the presence of ash. Nuclear magnetic resonance (NMR) data is provided for the major MEA degradation compounds such as N-(2-hydroxyethyl)formamide (HEF) and N-(2-hydroxyethyl)imidazole (HEI) along with the characterisation of a new MEA oxidative degradation product, N-(2-hydroxyethyl)imidazole-N-oxide (HEINO) which had been previously misassigned. Degradation products were quantified using ¹H NMR and gas chromatography mass spectrometry (GC–MS) to assess the impact of potassium and various ashes from combustion (olive, white wood and two types of coal ash) on the rates of amine degradation. Woody biomass fly ashes were found to reduce the presence of the oxidative degradation products. Both types of coal fly ash and the olive biomass ash were found to enhance the formation the newly identified degradation product, HEINO. Solvent samples taken from a pilot scale facility support these laboratory findings.