Study On Enhancing Carbon Dioxide Absorption By Dispersed Droplets System

Global warming has become a challenge task and threatened our environment. Carbon Dioxide is the main greenhouse gas, contributing to the change of long term climate. Therefore, it is necessary to decrease CO₂ emissions. Absorption, including chemical absorption and physical absorption, is the most mature technique to capture CO₂. However, this technique has some drawbacks, such as low absorption rate for physical absorption, high corrosion to equipment as well as high energy consumption for chemical absorption. It has been known that dispersed droplets can enhance gas mass transfer rate in gas-liquid interface. In this study, dispersed droplets were used to enhance CO₂ absorption so as to improve the absorption rates. Ionic liquid which has high solubility of CO₂, low vapor pressure and weak corrosive was employed to prepare the dispersed phase. At the same time the emulsion liquid membrane was used to capture and storage CO₂. On the one hand, dispersed droplets can enhance mass transfer rate, and on the other hand, CO₂ can be strorged by synthesizing CaCO3 fine particles.Oil-in-water ionic liquid emulsion was used to enhance CO₂ mass transfer during the period of physical absorption, whose dispersed-phase was a kind of ionic liquid, 1-octyl-3 methyl imidazole six phosphate fluoride. The effects of some operation parameters on absorption rate were investigated. Experiments prove that ionic liquid emulsion can enhance the physical absorption of CO₂, whose average absorption rate increased to 45.5%, and the main mechanism for enhancing mass transfer rate is Shuttle effect. Some operation parameters, such as operation temperature, droplets size, and volume fractions of dispersed phase, all have effect on mass transfer rate in gas-liquid interface. After dispersion was regenerated for six times, regeneration efficiency are still high up to 86%.Oil-in-water ionic liquid emulsion whose continuous phase was trethanol amine aqueous solution and dispersed phase was 1-octyl-3 methyl imidazole six phosphate fluoride, was used to enhance mass transfer of CO₂ in trethanol amine aqueous. Experiments prove that ionic liquid emulsion can enhance the absorption of CO₂ in trethanol amine aqueous, whose average absorption rate increased 23.3% compared with trethanol amine aqueous solution without ionic liquid dispersion. The collaborative action of hydrodynamic effect and shuttle effect promotes the mass transfer of CO₂ in gas-liquid for chemical absorption. Operation temperature, the volume fraction of dispersed phase and other factors all have effect on mass transfer rate. After three times regeneration of dispersion, regeneration efficiency are still high up to 93.4%.Water-in-oil-in-water emulsions were prepared, whose internal phase was Ca (OH)₂ solution, external phase was water, and kerosene was oil phase. The W/O/W emulsion liquid membrane was used to enhance mass transfer of CO₂ in water, companying with the synthesizing fine CaCO3 particles in the internal phase. Experiments prove that emulsion liquid membrane can enhance the absorption of CO₂ in water whose average absorption rate increased 36.7% compared to the absorbent without emulsion. At the same time, a few fine CaCO3 fine particles can be prepared.