Microwave regeneration of monoethanolamine aqueous solutions used for CO2 capture

Aqueous amine absorbents are widely used in post-combustion CO2 capture processes. To strip the CO2, the solutions are usually heated around 110–140 °C using a steam reboiler located at the bottom of the regeneration column. In this work, microwave irradiation was studied as a new alternative to heat and regenerate CO2-rich monoethanolamine (MEA) aqueous solutions. Various parameters like the amine concentration, the regeneration temperature and the initial microwave power were modified to assess regeneration efficiencies by microwave heating and to find optimal experimental conditions in term of recovered CO2 amount and energy consumption.

The heating rate of solutions by microwave was found to be mostly influenced by their heat capacity, viscosity and CO2 loading. The optimal heating rate was found for the 50 wt% MEA solution and regeneration performance parameters, based on the CO2 stripped quantity and microwave energy absorbed by the solution, were also found to be optimal at this concentration. Using a 50 wt% MEA solution instead of the well-known 30 wt% gave a 13% increase in the CO2 cyclic capacity while the regeneration energy consumption decreased by 15% under the optimal conditions tested in this work. These results indicate that the 50 wt% MEA solution seems to offer great potential in a cyclic CO2 absorption-microwave regeneration process.