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

Abstract

The “coordinative effect” was discovered in MEA + DEA bi‐solvents already, and it enhances both CO2 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 CO2 absorption and desorption processes were performed onto MEA + AMP and MEA + BEA (0.1 + 2–0.5 + 2 mol/L) separately. The CO2 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 CO2 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 pKa were two main factors that determine negligible–strong coordinative effects between AMP and BEA; different pKa reflected the optimized blending ratios of MEA + DEA (3/7) and MEA + BEA (2/20).

Evaluating CO2 Desorption Activity of Tri-Solvent MEA + EAE + AMP with Various Commercial Solid Acid Catalysts

“…The "coordinative effect" was revealed to exist in MEA + RR'NH bi-blends, such as MEA + DEA [55] and MEA + BEA [56]; and MEA + BEA + AMP [23], MEA + EAE and MEA + EAE + AMP [57]. The heat duty of MEA + RR'NH bi-blends at a narrow but specific ratio is even lower than that of single secondary amines [55,56,58].…”

“…This simultaneous increase both Q input and nCO 2 resulted in the reduction of heat duty (HD = Q input /nCO 2 ) down to 5-10%. [58]. The principle of heat duty reduction provides two options: (1) reduce Q input directly, as is common; (2) enhance Q input and nCO 2 simultaneously under a specific ratio [58].…”

“…[58]. The principle of heat duty reduction provides two options: (1) reduce Q input directly, as is common; (2) enhance Q input and nCO 2 simultaneously under a specific ratio [58]. The detailed mechanism was published repeatedly, to indicate extra nCO 2 production with blending of MEA [23,55,56,[59][60][61].…”

“…The heat duty (HD) was one of the most important parameters with which to evaluate energy efficiency for various combinations [58]. For this study, combinations with various HD could be compared because of their similar amine concentrations.…”

Structure–Activity Correlation Analyses of MEA + 3A1P/MAE Isomers with a Coordinative Effect Study

“…It was the "coordinative effect", which happened if blending a minute concentration of MEA into RR′NH DEA 19−22 and BEA. 22 Liu 20 and Shi 21 reported "coordinative effect" within MEA + DEA bi-blends that blending MEA with single amine can enhance CO 2 absorption 20 and desorption 21,23 of single amine simultaneously. This concept was abnormal to the generally accepted idea that "blending MEA into single amine solvents can enhance CO 2 absorption but deteriorate CO 2 desorption".…”