Novel Inverse Supported Ionic Liquid Absorbents for Acidic Gas Removal from Flue Gas
2016-04-18T00:00:00Z (GMT) by
This work reports on the astonishing high capacity of inverse supported ionic liquid absorbents, hereinafter denoted as “inverse SILPs” to remove acidic gases (SO<sub>2</sub> and CO<sub>2</sub>) from flue gas streams. These nonconventional SILPs are easily prepared in the form of flowing powder via a phase inversion technique and consist of tiny ionic liquid (IL) droplets enclosed into an ultrathin, porous solid sleeve of pyrogenic silica nanoparticles. The CO<sub>2</sub>/N<sub>2</sub> and SO<sub>2</sub>/CO<sub>2</sub> separation performance and regeneration efficiency of inverse SILPs developed from six different ILs and two IL/chitosan ionogels was examined via gravimetric CO<sub>2</sub>, N<sub>2</sub> absorption isotherms and via SO<sub>2</sub>, CO<sub>2</sub>, O<sub>2</sub> breakthrough curves from gas mixtures in fixed beds. The involved ILs varied from chemisorbing ones, composed of alkyl- or alkanol-ammonium cations and amino acid anions, to physisorbing ones including ether functionalized anions and 1-alkyl-3-methylimidazolium cations. It is noteworthy that the best performing inverse SILP consisted of a very common IL, the 1-butyl-3-methylimidazolium chloride [BMIM][Cl], the absorption capacity of which was slightly enhanced by dissolving 5 wt % of chitosan to form the respective ionogel. The material’s performance was stable in repeated cycles of absorption and regeneration at 60 °C under helium flow, exhibiting SO<sub>2</sub>/CO<sub>2</sub> selectivity of above 300, while the SO<sub>2</sub> and CO<sub>2</sub> absorption capacity was 1.6 and 0.6 mmol/g respectively at 25 °C, in a gas stream of 1 bar composed of 0.13 vol % SO<sub>2</sub>, 13 vol % CO<sub>2</sub>, 11.5 vol % O<sub>2</sub> and N<sub>2</sub> (balance).