Nitrile-functionalized tertiary amines as highly efficient and reversible SO2 absorbents

• Published in: Journal of hazardous materials 2014-01, Vol.264, p.136-143
• Main Authors: Hong, Sung Yun, Kim, Heehwan, Kim, Young Jin, Jeong, Junkyo, Cheong, Minserk, Lee, Hyunjoo, Kim, Hoon Sik, Lee, Je Seung
• Format: Article
• Language: English
• Subjects: Absorbent; Absorption, stripping; Adsorption; Amine; Amines - chemistry; Applied sciences; Chemical engineering; Exact sciences and technology; Nitrile; Nitriles - chemistry; Pollution; Recycle; SO2; Sulfur Dioxide - isolation & purification
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2013.11.026

•Nitrile-functionalized tertiary amines physically and reversibly absorb SO2.•Tertiary alkanolamines chemically and irreversibly absorb SO2 through OH group.•SO2 absorption modes were studied by spectroscopy and computational calculations. Three different types of nitrile-functionalized amines, including 3-(N,N-diethylamino)propionitrile (DEAPN), 3-(N,N-dibutylamino)propionitrile (DBAPN), and N-methyl-N,N-dipropionitrile amine (MADPN) were synthesized, and their SO2 absorption performances were evaluated and compared with those of hydroxy-functionalized amines such as N,N-diethyl-N-ethanol amine (DEEA), N,N-dibutyl-N-ethanol amine (DBEA), and N-methyl-N,N-diethanol amine (MDEA). Absorption–desorption cycle experiments clearly demonstrate that the nitrile-functionalized amines are more efficient than the hydroxy-functionalized amines in terms of absorption rate and regenerability. Computational calculations with DBEA and DBAPN revealed that DBEA bearing a hydroxyethyl group chemically interacts with SO2 through oxygen atom, forming an ionic compound with a covalently bound OSO2− group. On the contrary, DBAPN bearing a nitrile group physically interacts with SO2 through the nitrogen and the hydrogen atoms of the two methylene groups adjacent to the amino and nitrile functionalities.