Enhancements in mass transfer for carbon capture solvents part II: Micron-sized solid particles

The mass transfer of CO₂ into amine-based carbon capture solvents was improved with the addition of heterogeneous micron- and nano-sized particle additives. Enhancement in CO₂ removal rate was determined in a stirred reactor with a flat steady gas-liquid interface and in a small packed-bed absorption column. The screening of several particle types in the stirred reactor indicated that carbon particles are best suited to enhance the rate of CO₂ diffusion in 30 wt.% monoethanolamine (MEA), and tests in the small packed-bed absorption column showed improved CO₂ mass transfer in three solvents, MEA, piperazine (PZ), and hexanediamine (HDA), upon addition of nano-sized activated carbon particles. The enhancement of CO₂ capture efficiency and K_G increases with increasing solvent kinetics, in order of methyldiethanolamine (MDEA) < MEA < PZ < HDA, confirming the particle additives have a larger impact on kinetically faster, liquid-side diffusion limited, solvents. The combined benefits of the particle additives were then demonstrated on an absorption-desorption integrated bench-scale CO₂ capture unit, in both MEA and the thermally stable advanced amine blend: 1-amino-2-propanol (A2P)/2-amino-2-methyl-1-propanol (AMP). The combined system translated to an overall 26% reduction in energy penalty for CO₂ capture on the CAER Bench-scale unit.