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An ionic liquid (IL) [P66614][Triz] with a low regeneration temperature was loaded on a graphene nanoplatelet (GNP) and reduced graphene oxide (RGO) to accelerate the CO2 absorption rate. High-resolution transmission electron microscopy (HRTEM) patterns showed that GNP was composed of a regular “honeycomb” lattice, but a regular lattice structure was not observed for RGO as a result of the functional group on it. The CO2 absorption capacity (63.6 mg of CO2/g of IL) and absorption peak rate (22.4 mg of CO2 g–1 of IL min–1) of IL loaded on GNP were increased by 8.2 and 72.3%, respectively, compared to those of neat IL. The supported IL performed better because [P66614][Triz] was oriented in a favorable dispersion as a result of the negative ζ potential of the GNP surface. In contrast, the CO2 absorption rate of RGO–20% IL (mass ratio of RGO/IL = 4:1) was lower than that of IL, which could be attributed to the hydrogen bond between surface oxygen functional groups and IL. 13C nuclear magnetic resonance and M...

A phase-change solvent for CO2 absorption was prepared by mixing N-methyl-1,3-diaminopropane (MAPA) and N,N-dimethylformamide (DMF). In this MAPA/DMF solvent, MAPA-carbamate precipitate was formed after CO2 absorption to facilitate reducing energy consumption of amine regeneration. The CO2 uptake of MAPA/DMF solvent (14.8 mg/g solvent) was increased by 22% compared with that of MAPA/water solvent (12.1 mg/g solvent). For MAPA/DMF solvent, time was reduced by 22% to reach the CO2 absorption equilibrium. The maximum CO2 uptake rate of MAPA/DMF solvent was 30% higher than that of MAPA/water solvent because DMF displayed higher CO2 solubility and lower MAPA-carbamate solubility than water. Differential scanning calorimetry and thermogravimetry experiments revealed that MAPA(H+)2 and MAPA(CO2–)2 compositions in MAPA-carbamate precipitate first decomposed (peak temperature = 59.9 °C). Subsequently, the MAPACO2 compositions in precipitate also decomposed (peak temperature = 124.2 °C).

With the upgrading of fermentative biogas to produce gaseous transport fuel, ionic liquid (IL) [P66614][2-Op], which adsorbed CO2 through multiple-site cooperative interactions, was loaded onto molecular sieve MCM-41 to adsorb CO2 in a biohythane atmosphere (CH4 + H2 + CO2). [P66614][2-Op] loaded onto MCM-41 exhibited a higher CO2 adsorption rate than pure IL during the initial stage because of its larger reaction surface area. However, the CO2 adsorption rate of [P66614][2-Op] loaded onto MCM-41 became lower than that of pure IL as the reaction continued because CO2 was inaccessible to the IL blocked within the inner pores of MCM-41. The CO2 adsorption rate of IL loaded onto the molecular sieve (MCM-41–50% IL) was (51.5 mg of CO2 g–1 of IL min–1) 2.1 times higher than that of pure IL during the initial 1 min in a pure CO2 atmosphere and was (24.6 mg of CO2 g–1 of IL min–1) 2.2 times higher than that of pure IL during the initial 2 min in a biohythane atmosphere.