Study of “coordinative effect” within bi‐blended amine MEA + AMP and MEA + BEA at 0.1 + 2–0.5 + 2 mol/L with absorption–desorption parameter analyses

The “coordinative effect” was discovered in MEA + DEA bi‐solvents already, and it enhances both CO 2 absorption and desorption within MEA + RR'NH simultaneously. A recent study verified strong coordinative effects within MEA + BEA (RR'NH) + AMP tri‐solvents, but whether the coordination was 100% attributed to interaction of MEA + BEA needs to be confirmed. This study investigated the “coordinative effect” separately within MEA + AMP (hindered amine) and MEA + BEA (RR'NH). The CO 2 absorption and desorption processes were performed onto MEA + AMP and MEA + BEA (0.1 + 2–0.5 + 2 mol/L) separately. The CO 2 absorption–desorption parameters were calculated to evaluate the coordinative effects on a consistent level. Results indicated negligible “coordinative effect” within MEA + AMP but strong coordination within MEA + BEA. Both CO 2 absorption and desorption performance of MEA + BEA (0.2 + 2 mol/L) was better than 2.0 mol/L BEA simultaneously. The coordinative effect was optimum within MEA + BEA bi‐solvents at 0.2 + 2 mol/L close to 0.3 + 2 + 2 mol/L of MEA + BEA + AMP tri‐solvents. Based on analysis, carbamate stability and pK a were two main factors that determine negligible–strong coordinative effects between AMP and BEA; different pK a reflected the optimized blending ratios of MEA + DEA (3/7) and MEA + BEA (2/20).