Details

Autor(en) / Beteiligte

• Kortunov, Pavel V
• Baugh, Lisa Saunders
• Siskin, Michael

Titel

Pathways of the Chemical Reaction of Carbon Dioxide with Ionic Liquids and Amines in Ionic Liquid Solution

Ist Teil von

• Energy & fuels, 2015-09, Vol.29 (9), p.5990-6007

Ort / Verlag

American Chemical Society

Erscheinungsjahr

2015

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• This paper focuses specifically on certain ionic liquids that are capable of acting as chemisorbents for CO2 at ambient pressure and temperature. This low-pressure approach based on chemical reactivity is more effective than traditional physical absorption/solubility approaches for CO2 capture in ionic liquids for higher pressure carbon capture. We describe a class of imidazolium ionic liquids bearing a relatively acidic hydrogen atom at C-2, which upon initial abstraction develops a nucleophilic carbon atom that is carboxylated by CO2. Basicity of the anion plays a role in the ability to remove the acidic hydrogen to generate the nucleophilic carbon. The yield of carboxylated ionic liquid is not affected by non-aqueous co-solvents but changes as a function of the CO2 partial pressure, solution temperature, and presence of H2O in solution. CO2 chemisorption by ionic liquids is particularly efficient in the presence of a non-nucleophilic nitrogenous base that serves to promote ionic liquid carboxylation and stabilize the carboxylic acid product as a salt. Selected ionic liquids are able to stabilize the formation of amine carbamic acids in the ionic liquid solution. In this case, each amine captures up to 1 CO2 molecule, which is beneficial for the overall CO2 capacity in the solution. Carboxylation of the ionic liquids themselves is lower because the basic anion of the ionic liquid also stabilizes N-carboxylated products. In situ 13C and 1H nuclear magnetic resonance (NMR) spectroscopy using a built-in micro reactor was used to provide real-time insights on CO2–ionic liquid and CO2–amine reaction pathways and product speciation under various conditions.