Trio-amine blends combined with fly ash-catalyzed desorption: A synergistic approach for energy-efficient CO2 capture

Blended amine systems are increasingly investigated to develop sustainable and energy-efficient CO2 capture processes. This work explores novel ternary amine formulations combining the tertiary amine 2-(2-(dimethylamino)ethoxy)ethanol (DMAEE) with 2-(ethylamino)ethanol (EAE), 2-amino-2-methyl-1-propanol (AMP), and piperazine (PZ). Their CO2 capture performance was assessed through absorption and desorption tests at 40 °C and 100 °C, respectively, and reaction pathways were elucidated via 13C NMR speciation analysis. Among the tested systems, the EAE:DMAEE:AMP 2:1:2 blend showed the best regeneration performance, achieving a ∼ 67 % reduction in energy demand compared to conventional 5 M monoethanolamine (MEA), while also improving desorption rate and cyclic capacity. To further enhance regeneration, a catalytic strategy was implemented using fly ash (FA), a low-cost solid acid catalyst previously validated for MEA. FA proved effective with the ternary blend as well, though its catalytic effect was less pronounced than with MEA. This behavior was rationalized by linking catalyst activity to solution speciation, showing that FA is more active in carbamate-rich systems. These findings highlight the potential of DMAEE-based blends for low-energy CO2 capture and suggest new design strategies for sorbents optimized for catalytic regeneration.