Oxidation of amines at absorber conditions for CO2 capture from flue gas

Eleven amines that are suitable for CO2 capture by an amine scrubbing system have been evaluated for their stability in the presence of oxygen. Six amines produced measureable quantities of ammonia in the order: 1, 2-diamino-propane (DAP) > monoethanolamine (MEA) > ethylene diamine (EDA) > 3-methylamino-1-propylamine (MAPA) > potassium glycinate (GLY) > potassium taurinate (TAU). Five other amines produced no detectable ammonia (<0.2 mmol/kg/hr): piperazine (PZ), 1-methyl-piperazine (1-MPZ), diglycolamine (DGA®), 2-amino-2-methyl-propanol (AMP), and 1-methyl-diethanolamine (MDEA). The effect of temperature on ammonia production from aqueous MEA in the presence of Inh. A was also measured. The activation energy of ammonia production varied from 86 kJ/mol with no inhibitor to 133 kJ/mol with 200 mM Inh. A. At 55 °C, ammonia production was reduced by 74–99% with 50-200 mM Inh. A.