TY - JOUR
T1 - Molecular dynamics simulation of anion effect on solubility, diffusivity, and permeability of carbon dioxide in ionic liquids
AU - Liu, Hongjun
AU - Dai, Sheng
AU - Jiang, De En
PY - 2014/6/25
Y1 - 2014/6/25
N2 - The solubility, diffusivity, and permeability of CO2 in three ionic liquids with a common cation were investigated by molecular dynamics simulations in order to understand the role of the anion in dictating permeability. The three ionic liquids are 1-ethyl-3-methyl imidazolium tetracyanoborate ([emim][B(CN)4]), 1-ethyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]), and 1-ethyl-3-methyl imidazolium tetrafluoroborate ([emim][BF4]). The simulated solubility agrees satisfactorily with experiment with a trend of [emim][B(CN)4] > [emim][Tf2N] > [emim][BF 4]. The higher solubility of CO2 in [emim][B(CN) 4] appears to be due to weaker cation-anion interaction, higher fraction of larger cavity, larger free volume, and more favorable interaction with CO2. CO2 diffusivity in ILs follows the same trend as solubility. On the basis of the solvation-diffusion mechanism, gas permeability was estimated and compared with experiment. The present work confirms the superiority of tetracyanoborate-based ILs for membrane-based gas separations.
AB - The solubility, diffusivity, and permeability of CO2 in three ionic liquids with a common cation were investigated by molecular dynamics simulations in order to understand the role of the anion in dictating permeability. The three ionic liquids are 1-ethyl-3-methyl imidazolium tetracyanoborate ([emim][B(CN)4]), 1-ethyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]), and 1-ethyl-3-methyl imidazolium tetrafluoroborate ([emim][BF4]). The simulated solubility agrees satisfactorily with experiment with a trend of [emim][B(CN)4] > [emim][Tf2N] > [emim][BF 4]. The higher solubility of CO2 in [emim][B(CN) 4] appears to be due to weaker cation-anion interaction, higher fraction of larger cavity, larger free volume, and more favorable interaction with CO2. CO2 diffusivity in ILs follows the same trend as solubility. On the basis of the solvation-diffusion mechanism, gas permeability was estimated and compared with experiment. The present work confirms the superiority of tetracyanoborate-based ILs for membrane-based gas separations.
UR - http://www.scopus.com/inward/record.url?scp=84903471121&partnerID=8YFLogxK
U2 - 10.1021/ie501501k
DO - 10.1021/ie501501k
M3 - Article
AN - SCOPUS:84903471121
SN - 0888-5885
VL - 53
SP - 10485
EP - 10490
JO - Industrial and Engineering Chemistry Research
JF - Industrial and Engineering Chemistry Research
IS - 25
ER -