Chemical and Physical Absorption of SO2 by N-Functionalized Imidazoles: Experimental Results and Molecular-level Insight

Abstract

Sulfur dioxide (SO2) removal is a key component of many industrial processes, especially coal-fired power generation. Controlling SO2 emissions is vital to maintaining environmental quality, as SO2 is a contributor to acid rain, but has value as a chemical feedstock. Although a number of novel solvents/materials including ionic liquids (ILs) have recently been proposed for alternatives to limestone scrubbing for SO2 capture/removal from point sources, the imidazole architecture presents a convenient, inexpensive and efficient class of low volatility and low viscosity solvents to accomplish this goal. On the basis of our prior work with imidazoles for CO2 capture, we have extended our interests toward understanding the relationship between imidazole structure and SO2 absorption. Using a series of imidazole compounds with various substituents at the 1, 2 and/or 4(5) positions of the five-membered ring, SO2 absorption via both chemical and physical mechanisms was observed. The chemical absorption product is ...