Experimental investigation of CO₂ absorption enthalpy in conventional imidazolium ionic liquids

Abstract

Ionic liquids (ILs) have elicited considerable attention in the field of gas absorption and separation due to their unique properties. In addition to absorption capacity and absorption rate, absorption enthalpy is an important indicator for sorbent evaluation. In this work, the absorption enthalpy of CO2 in several kinds of ILs was measured directly using a Calvet calorimeter. The effects of anions, cationic alkyl chain length, and temperature on absorption properties were discussed. Results showed that anions influenced CO2 absorption enthalpy considerably. 1‐Butyl‐3‐methylimidazolium acetate presented the most appropriate enthalpy for CO2 absorption compared with the other ILs investigated with different chain lengths. Absorption enthalpy was dependent on temperature, and the isosteric absorption enthalpy decreased with an increase in temperature. This work provides a useful basis for the appropriate selection of alternative forms of IL sorbents for post‐combustion CO2 capture technology. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.

Phenoxy-Nitrile Bifunctional Ionic Liquid for Efficient Electroreduction of CO2 to Oxalate

“…Moreover, the CO 2 capacity in [TBP]­[p-CN-PhO] was 0.53 mol CO 2 ·mol IL –1 (Figure S4), the highest being nearly 30 times that of conventional ILs (Table S1). − The higher CO 2 concentration in the IL electrolyte will facilitate the CO 2 electroreduction . Considering the hindrance of CO 2 mass transfer in the high-viscous electrolyte of pure [TBP]­[p-CN-PhO], a hybrid system of IL and organic solvent was chosen to enhance the CO 2 electroreduction performance.…”

Aprotic phosphonium‐based ionic liquid as electrolyte for high CO2electroreduction to oxalate

“…The CO 2 absorption curve of [P 4444 ][4‐MF‐PhO] was plotted in Figure S5, and the related results of CO 2 capacity in different solvents were listed in Table S1. The results indicate that the phosphonium‐based IL [P 4444 ][4‐MF‐PhO] has higher CO 2 capacity of 0.0349 g CO 2 per g IL at 303.15 K and ambient pressure than conventional ILs (Table S1), 46 so the combination of [P 4444 ][4‐MF‐PhO] and AcN can greatly improve CO 2 concentration and promote CO 2 RR in the IL‐based electrolyte.…”

“…The results indicate that the phosphonium-based IL [P 4444 ][4-MF-PhO] has higher CO 2 capacity of 0.0349 g CO 2 per g IL at 303.15 K and ambient pressure than conventional ILs (TableS1),46 so the combination of [P 4444 ][4-MF-PhO] and AcN can greatly improve CO 2 concentration and promote CO 2 RR in the IL-based electrolyte.…”

Promotion of CO2 capture performance using piperazine (PZ) and diethylenetriamine (DETA) bi‐solvent blends

“…1,2 Capturing CO 2 from flue gas using chemical absorption methods is considered to be an effective way to reduce CO 2 emissions. [3][4][5] The most reliable and economical regeneration process because of its high desorption temperature and high desorption enthalpy, which greatly increase the industrial operating cost and limit its industrial application. 10 Another amine used in industry, the tertiary amine N-methyldiethanolamine (MDEA), has low regeneration energy consumption, but high viscosity hinders its heat and mass transfer during the CO 2 absorption process, thus limiting its absorption rate and capacity.…”

“…Global warming, caused by excessive carbon dioxide (CO 2 ) emissions, has become a major environmental issue worldwide . Capturing CO 2 from flue gas using chemical absorption methods is considered to be an effective way to reduce CO 2 emissions . The most reliable and economical technology for CO 2 capture is by absorption using amine‐based solvents because it can handle large volumes of flue gas and capture more than 90% of CO 2 .…”