An investigation of some sterically hindered amines as potential carbon dioxide scrubbing compounds

In order to improve the efficiency of the carbon dioxide cycling process and to reduce amine emissions, a series of nonvolatile amino acid salts with sterically hindered amine groups were investigated to determine their potential as direct replacements for monoethanolamine (MEA) in submarine-based CO2 scrubbers. Absorption from atmospheres containing various levels of CO2 was measured to assess the total capacities and absorption rates of amine solutions. The regeneration rates and extent of CO2 desorption were established by heating these solutions. C-13 NMR spectroscopy was used to establish reaction products and solution compositions after both absorption and desorption. Methyl groups substituted adjacent to the amine were found to increase solution absorption capacities but with an overall reduction in absorption rate. Poor absorption rates at low CO2 levels and precipitation problems would prevent the alpha-dimethylamines examined from being used in existing submarine scrubbers. These amines, however, show potential as replacements in industrial CO2 scrubbing processes.