Experimental study on CO₂ capture by MEA/n-butanol/H₂O phase change absorbent

Monoethanolamines (MEAs) are widely used for CO₂ capture, but their regeneration energy consumption is very high. CO₂ Phase change absorbents (CPCAs) can be converted into CO₂-rich and CO₂-lean phases after absorbing CO₂, and the regeneration energy consumption can be reduced because only the CO₂-rich phase is thermally desorbed. In this paper, a novel CPCA with the composition "MEA/n-butanol/H₂O (MNBH)" is proposed. Compared with the reported MEA phase change absorbent, the MNBH absorbent has higher CO₂ absorption capacity, smaller absorbent viscosity and CO₂-rich phase volume. The MNBH absorbent has the highest CO₂ absorption capacity of 2.5227 mol CO₂ per mol amine at a mass ratio of 3 : 4 : 3. The CO₂ desorption efficiency reaches 89.96% at 120 °C, and the CO₂ regeneration energy consumption is 2.6 GJ tCO₂^-1, which is about 35% lower than that of the 30 wt% MEA absorbent. When the mass ratio of MNBH absorbent was 3 : 6 : 1, the CO₂ recycling capacity was 4.1918 mol CO₂ L^-1, which is 76% higher than that of the conventional 30 wt% MEA absorbent. The phase change absorbent developed in this paper can reduce the desorbent volume by about 50% and has good absorption performance for CO₂ in flue gas.