A comparative analysis of microwave-assisted regeneration against conventional regeneration for post-combustion carbon capture

This study investigates the feasibility of microwave regeneration of molecular sieves (two activated carbons - AC1 and AC2 - and a zeolite) in a dynamic swing adsorption system. The adsorbents' performance was assessed using both microwave swing adsorption (MWSA) and conventional temperature swing adsorption (TSA). Experiments were run with a pre-cleaned flue gas (15% CO2 in N2) to which 15 % v/v of H2O was added to simulate carbon capture in a coal-fired power plant. A comparative analysis of both heating sources was established by measuring key process performance parameters including working capacity, CO2 purity, productivity, recovery and regeneration extent. Whilst TSA produced a higher productivity for sample AC2, MWSA proved overall more advantageous than TSA across all three adsorbents, with higher purities, productivities and recoveries recorded. Furthermore, the influence of moisture present in the flue gas on the process performance was studied with MWSA and TSA cycles also using dry flue gas. Experimental results showed that both AC1 and zeolite exhibit substantially higher working capacities under MWSA than TSA, due to higher regeneration being achieved under MWSA. Additionally, the size of the sample in AC1 was incremented by 8 times to investigate the influence of sample size on MWSA and TSA cycles. Overall, results showed MWSA to be more advantageous than TSA with the larger sample. This study shows that MWSA is a viable option for adsorbent regeneration and also presents advantages over conventional TSA.