Equimolar CO(2) capture by imidazolium-based ionic liquids and superbase systems

Journal Article · Fri Jan 01 04:00:00 EST 2010 · Green Chemistry

OSTI ID:1044699

Dai, Sheng ^[1]; Wang, Chongmin ^[2]; Luo, Huimin ^[1]; Luo, Xiaoyan ^[3]; Li, Qing ^[1]; Li, Haoran ^[3]

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1. ORNL
2. Pacific Northwest National Laboratory (PNNL)
3. Zhejiang University

Imidazolium-based ionic liquids continue to attract interest in many areas of chemistry because of their low melting points, relatively low viscosities, ease of synthesis, and good stabilities against oxidative and reductive conditions. However, they are not totally inert under many conditions due to the intrinsic acidity of hydrogen at the C-2 position in the imidazolium cation. In this work, this intrinsic acidity was exploited in combination with an organic superbase for the capture of CO{sub 2} under atmospheric pressure. During the absorption of CO{sub 2}, the imidazolium-based ionic liquid containing an equimolar superbase reacted with CO{sub 2} to form a liquid carboxylate salt so that the equimolar capture of CO{sub 2} with respect to the base was achieved. The effects of ionic liquid structures, types of organic superbases, absorption times, and reaction temperatures on the capture of CO{sub 2} were investigated. Our results show that this integrated ionic liquid-superbase system is capable of rapid and reversible capture of about 1 mol CO{sub 2} per mole of ionic liquid. Furthermore, the captured CO{sub 2} can be readily released by either heating or bubbling N{sub 2}, and recycled with little loss of its capture capability. This efficient and reversible catch-and-release process using the weak acidity of the C-2 proton in nonvolatile imidazolium-based ionic liquids provides a good alternative to the current CO{sub 2} capture methods that use volatile alkanols, amines, or water.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1044699
• Journal Information: Green Chemistry, Journal Name: Green Chemistry Journal Issue: 11 Vol. 12; ISSN 1463-9262
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
ABSORPTION
AMINES
ATMOSPHERIC PRESSURE
CHEMISTRY
HEATING
HYDROGEN
MELTING POINTS
MOLTEN SALTS
PH VALUE
PROTONS
SYNTHESIS
WATER