Experimental Evaluation of Effect of Oxidative Degradation of Aqueous Monoethanolamine on Heat of CO2 Absorption, Vapor Liquid Equilibrium and CO2 Absorption Rate

Abstract

Oxidative degradation produces carboxylic acids which are one of the undesirable degradation products and may have a negative impact on the CO 2 separation energy of post combustion capture system. 30wt% MEA solutions mixed with carboxylic acids were regarded as a simulated solution for degraded MEA and effect of the additives on heat of CO 2 absorption, equilibrium CO 2 loading and CO 2 absorption rate were experimentally evaluated by using a differential reaction calorimetry (DRC) apparatus, a pressurized vessel to obtain vapor liquid equilibrium (VLE) data and a gas-liquid contactor, respectively. At the range of CO 2 loading from 0.0 to 0.3 mol-CO 2 /mol-amine, the heat of CO 2 absorption of the simulated solution increased by around 10% compared to the normal MEA solution. Moreover, the changing-point of the heat of CO 2 absorption of the simulated solution moved to a leaner CO 2 loading compared to the normal solution. Result of a 13 C-NMR analysis also indicated the change in reaction mechanism. At the absorber condition, the equilibrium CO 2 loading of the simulated solution decreased by 20% in comparison with the normal solution, where it decreased by 10% at the stripper condition and therefore the cyclic CO 2 loading also decreased. Both CO 2 absorption rates decreased linearly but in different gradients with increasing CO 2 loading. Higher pH in the simulated solution kept higher CO 2 absorption rate, which is consistent with the result of pH measurement.

Handling heat‐stable salts in post‐combustion CO2 capture: A detailed survey

“…This supports the earlier reports by Nakagaki et al. on the CO 2 absorption rate of an MEA solution containing carboxylic acids where they suggested that the detrimental effect of the presence of HSSs can be partly impeded if the CO 2 absorption rate of an absorbing solution is maintained at a high value within richer CO 2 loadings 100 . In their work, Weiland & Sivasubramanian also highlighted the beneficial presence of HSS to the operation of the stripper section alongside their damaging effects to the absorber operation 101…”

Experimental investigation on CO2 absorption and physicochemical characteristics of different carbon-loaded aqueous solvents

“…The pH of virgin 30 wt% MEA, AMP and PZ is 12.31, 12.53 and 12.74, respectively. CO 2 is an acid gas when it reacts with aqueous solutions, and pH decreases with the increase of CO 2 loading because of the acidic reaction through the zwitterion ion concept (Lv et al 2015;Nakagaki et al 2014). In this zwitterion ion mechanism, the reaction between CO 2 and aqueous solvents forms carbamate as an intermediate compound.…”