Multiobjective Evaluation of Amine-Based Absorbents for SO2 Capture Process Using the p K a Mathematical Model

Dongliang Wang; Jiangpeng Xie; Guixian Li; Wenliang Meng; Jingwei Li; Delei Li; Huairong Zhou

doi:10.1021/acsomega.1c05766

Multiobjective Evaluation of Amine-Based Absorbents for SO₂ Capture Process Using the p K _a Mathematical Model

ACS Omega. 2022 Jan 11;7(3):2897-2907. doi: 10.1021/acsomega.1c05766. eCollection 2022 Jan 25.

Authors

Dongliang Wang^{1

2}, Jiangpeng Xie^{1

2}, Guixian Li^{1

2}, Wenliang Meng^{1

2}, Jingwei Li^{1

2}, Delei Li³, Huairong Zhou^{1

2}

Affiliations

¹ School of Petrochemical Engineering, Lanzhou University of Technology, Lanzhou, Gansu 730050, China.
² Key Laboratory of Low Carbon Energy and Chemical Engineering of Gansu Province, Lanzhou, Gansu 730050, China.
³ Baiyin Nonferrous Group Co. LTD, Baiyin, Gansu 730900, China.

Abstract

The screening of high-efficiency and low-energy consumption absorbents is critical for capturing SO₂. In this study, absorbents with better performance are screened based on mechanism, model, calculation, verification, and analysis methods. The acidity coefficient (pK _a) 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 SO₂ cyclic absorption capacity per amine (α_c) in the amine-based SO₂ capture process is built based on the electroneutrality of the solution. Another model of desorption reaction heat (Q _des) is also built based on the van't Hoff equation. Correspondingly, α_c and Q _des of the above five diamines are calculated and verified with the experimental data. The results show that α_c of the diamine changes with the increase in the pK _a value, and the increase in the pK _a value directly leads to changes in Q _des. The order of α_c of the above five diamines is EDA > PZ > HEHPP > HEP > DIHEP, and the order of Q _des is EDA > PZ > HEHPP > DIHEP > HEP. The multiobjective analysis between α_c and Q _des suggests that it is not advisable to simply pursue a higher α_c while ignoring Q _des. The compound quaternary system absorbent has a wider range of α_c than the single ternary absorbent, which is the direction of absorbent development. This study is expected to strengthen absorbent screening for the amine-based SO₂ capture process from flue gas.