Abstract
A low-cost Transition Temperature Mixture (TTM) has been synthesized by
mixing ethylene glycol and potassium hydroxide as a new non-aqueous CO2
sorbent. Boric acid has been added to ensure the reversibility of the system
and a small amount of water to modulate the viscosity and optimize the
performances. The resulting mixtures have been characterized in terms of
viscosity, conductivity and density over temperature (therefore ionicity via Walden plots) and the effect of
temperature, pressure and the kinetics of the absorption have been evaluated.
Under optimized conditions, the four-component mixture EG/KOH/BA/H2O
3:1:1:3 can absorb 24 gCO2/kgsorbent in 30 minutes at 35°C
at 1 atm (59 after 4 h) and 60 gCO2/kgsorbent in 30
minutes at high pressure (10 and 20 atm, 80 gCO2/kgsorbent
after 50 min), while the desorption is quantitative after 30 minutes at only 60°C
under a gentle N2 flow. The system is robust enough to ensure
multiple absorption/desorption cycles.
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