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2112897 
Journal Article 
Degradation of aqueous piperazine in carbon dioxide capture 
Freeman, SA; Davis, J; Rochelle, GT 
2010 
Yes 
International Journal of Greenhouse Gas Control
ISSN: 1750-5836 
Elsevier Science, The Boulevard Kidlington Oxford OX5 1GB UK 
4 
5 
756-761 
WOS:000281345200005 
Concentrated, aqueous piperazine (PZ) is a novel solvent for carbon dioxide (CO sub(2)) capture by absorption/stripping. One of the major advantages of PZ is its resistance to thermal degradation and oxidation. At 135 and 150 C, 8 m PZ is up to two orders of magnitude more resistant to thermal degradation than 7 m monoethanolamine (MEA). After 18 weeks at 150 C, only 6.3% of the initial PZ was degraded, yielding an apparent first order rate constant for amine loss of 6.1 x 10 super(-9) s super(-1). PZ was the most resistant amine tested, with the other screened amines shown in order of decreasing resistance: 7 m 2-amino-2-methyl-1-propanol, 7 m Diglycolamine, 7 m N-(2-hydroxyethyl)piperazine, 7 m MEA, 8 m ethylenediamine, and 7 m diethylenetriamine. Thermal resistance allows the use of higher temperatures and pressures in the stripper, potentially leading to overall energy savings. Concentrated PZ solutions demonstrate resistance to oxidation compared to 7 m MEA solutions. Experiments investigating metal-catalyzed oxidation found that PZ solutions were 3-5 times more resistant to oxidation than MEA. Catalysts tested were 1.0 mM iron (II), 4.0-5.0 mM copper (II), and a combination of stainless steel metals (iron (II), nickel (II), and chromium (III)). Inhibitor A reduced PZ degradation catalyzed by iron (II) and copper (II). 
Piperazine; Carbon dioxide; CO(2) capture; Amine degradation; Oxidation