Multiobjective Evaluation of Amine-Based Absorbents for SO Capture Process Using the p Mathematical Model.

The screening of high-efficiency and low-energy consumption absorbents is critical for capturing SO. In this study, absorbents with better performance are screened based on mechanism, model, calculation, verification, and analysis methods. The acidity coefficient (p ) values of ethylenediamine (EDA), piperazine (PZ), 1-(2-hydroxyethyl)piperazine (HEP), 1,4-bis(2-hydroxyethyl)piperazine (DIHEP), and 1-(2-hydroxyethyl)-4-(2-hydroxypropyl)piperazine (HEHPP) are calculated by quantum chemical methods. A mathematical model of the SO cyclic absorption capacity per amine (α) in the amine-based SO capture process is built based on the electroneutrality of the solution. Another model of desorption reaction heat ( ) is also built based on the van't Hoff equation. Correspondingly, α and of the above five diamines are calculated and verified with the experimental data. The results show that α of the diamine changes with the increase in the p value, and the increase in the p value directly leads to changes in . The order of α of the above five diamines is EDA > PZ > HEHPP > HEP > DIHEP, and the order of is EDA > PZ > HEHPP > DIHEP > HEP. The multiobjective analysis between α and suggests that it is not advisable to simply pursue a higher α while ignoring . The compound quaternary system absorbent has a wider range of α than the single ternary absorbent, which is the direction of absorbent development. This study is expected to strengthen absorbent screening for the amine-based SO capture process from flue gas.