An Overview of Flue Gas SO₂ Capture Technology Based on Absorbent Evaluation and Process Intensification

Highly efficient and low-energy SO₂ capture technology is a key measure to control SO₂ pollution and sulfur supply side and demand-side balancing. This paper reviews the current development of SO₂ capture technology by chemical absorption from two aspects of absorbent and process enhancement. The SO₂ absorption mechanism of various absorbents are first described, and it was divided into aqueous solvents and nonaqueous solvents. Four prediction models for the SO₂ absorption capacity of different absorbents are proposed, providing an effective tool for the selection of efficient and low-energy absorbents. The advantages, bottlenecks, and development directions of each absorbent are analyzed. The diversity of organic amines provides a possibility for enhancing the market competitiveness of organic amine aqueous solutions in aqueous solvents, while the high energy consumption in the absorbent regeneration process is a disadvantage. The ionic amino acid aqueous solution reduces the volatilization of the effective components of the absorbent and has better SO₂ absorption potential than the organic amine aqueous solution. The greatest advantage of the nonaqueous solvents is the avoidance of ineffective latent heat consumption. High-throughput screening has become a bridge for the application of aqueous and nonaqueous solvents to industrial SO₂ capture processes. Finally, the application potential of a process intensification strategy in SO₂ capture technology is discussed, in which solvent intensification can avoid latent heat consumption, equipment intensification can improve the efficiency of gas–liquid mass transfer and process matching can recover the available energy of SO₂ capture system. The comprehensive evaluation of SO₂ capture process based on various absorbents is the primary task to promote the development of promising absorbents. It is hoped that this paper can provide reference for the development of SO₂ capture processes.