• Applied Chemistry for Engineering
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• v.25 no.6
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• pp.559-563
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• 2014

It is well known that $CO_2$ can be dissolved easily in imidazolium-based room temperature ionic liquids (RTILs). Because of the high $CO_2$ solubility in RTILs, membranes containing RTILs can separate easily gas mixtures such as $CO_2/N_2$ and $CO_2/CH_4$. In this study, we prepared poly(vinylidene fluoride)-hexafluoropropyl copolymer (PVDF-HFP) gel membranes with several RTILs and measured permeabilities of several gases. When the anion of ionic liquids was tetrafluoroborate($BF{_4}^-$), both $CO_2$ permeability and selectivities decreased as the carbon number of the cation increased. When the cation of ionic liquids was 1-ethyl-3-methylimidazolium[emim], $CO_2$ permeability of gel membranes containing bis(trifluoromethane) sulfoneimide($Tf_2N^-$) anion was double compared to those containing tetrafluoroborate($BF{_4}^-$) anion. However, $CO_2/N_2$ and $CO_2/CH_4$ selectivities of the $Tf_2N^-$ case were decreased, whereas the $H_2$ selectivity was almost the same for two cases.

• Korean Chemical Engineering Research
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• v.50 no.2
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• pp.217-222
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• 2012

The synthesis of dimethyl carbonate(DMC) is a promising reaction for the use of naturally abundant carbon dioxide. DMC has gained considerable interest owing to its versatile chemical reactivity and unique properties such as high oxygen content, low toxicity, and excellent biodegradability. In this study, the synthesis of DMC through the transesterification of ethylene carbonate(EC) with methanol was investigated by using ionic liquid and metal oxide catalysts. The screening test of different catalysts revealed that choline hydroxide ([Choline][OH]) and 1-n-butyl-3-methyl imidazolium hydroxide([BMIm][OH]) had better catalytic performance than metal salts catalysts such as MgO, ZnO and CaO. The effects of reaction parameters such as reaction temperature, MeOH/EC mole ratio, and carbon dioxide pressure on the reactivity of [Choline][OH] catalyst were discussed. High temperature and high MeOH/EC mole ratio were favorable for high conversion of EC. However, the yield of DMC showed a maximum when carbon dioxide pressure was 1.34 MPa, and then it decreased for higher carbon dioxide pressure. Zinc chloride($ZnCl_2$) was used as co-catalyst with the ionic liquid catalyst. The mixed catalyst showed a synergy effect on the EC conversion and DMC yield probably due to the acid-base properties of the catalysts.

• Membrane Journal
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• v.16 no.4
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• pp.268-275
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• 2006

Novel SILEMs were prepared by multi-stage phase separation process combined by the low temperature phase separation (LTPS) and the high temperature phase separation (HTPS) using room temperature ionic liquids (RTILs) which have a high ionic conductivity. PVDF and imidazolium series ionic liquids were used as membrane material and electrolyte, respectively. To study the ion conducting properties, the SILEMs were tested using LCR meter at temperature controlled from 30 to $130^{\circ}C$. Under humid conditions, with increasing temperature from 30 to $100^{\circ}C$, the ion conductivity of the cast $Nafion^{(R)}$ membrane increased linearly, but then started to decrease after $100^{\circ}C$. However, in the case of the SILEMs, with increasing operating temperature, the ion conductivity increased. Also, the ion conductivity behaviors of the SILEMs were almost same, regardless of humidity. The ion conductivity of the SILEMs was $2.7{\times}10^{-3}S/cm$ and increased almost linearly up to $2.2{\times}10^{-2}S/cm$ with increasing temperature to $130^{\circ}C$. The effects of an inorganic filler on the physical properties of the SILEMs were studied using the $SiO_2$. The addition of $SiO_2$ could improve the mechanical strength of the SILEMs, though the ionic conductivity was decreased slightly.