Preparation and Characterization of Nafion Composite Membranes Containing 1-ethyl-3-methylimidazolium Tetracyanoborate

Abstract

:The composite membranes using Nafion as matrix and 1-ethyl-3-methylimidazolium tetracyanoborate (EMITCB) as ion-conducting medium in replacement of water were prepared and characterized. The amount of EMITCB in Nafion varied from 30 to 50wt%. The composite membranes are characterized by ion conductivity, thermogravitational analyses (TGA) and small-angle X-ray scattering (SAXS). The composite membranes containing EMITCB of 40wt% showed the maximum ionic conductivity which was ~0.0146 S cm −1 at 423.15 K. It is inferred that the decrease in ionic conductivity of all the composite membranes might be due to the decomposition of a tetracyanoboric acid formed in the composite membranes. The results of SAXS indicated that the ionic clusters to conduct proton in the composite membranes were successfully formed. In accordance with the results of ionic conductivity as a function of a reciprocal temperature, SAXS showed a proportional decrease in scattering maximum q max as the amount of EMITCB increases in the composite membranes, which results in the increase in ionomer cluster size. The TGA showed no significant decomposition of the ionic liquid as well as the composite membranes in the range of operating temperature (120-150 o C) of high temperature proton exchange membrane fuel cells (HTPEMFC). As a result, EMITCB is able to play an important role in transferring proton in the composite membranes at elevated temperatures with no external humidification for proton exchange membrane fuel cells.

Economic Analysis and Life Cycle Environmental Assessment of Imidazolium-Based Ionic Liquids for Separation of the Methanol/Dimethyl Carbonate Azeotrope

“…The thermal decomposition loss formula was as follows: t 0.99 = normalA exp ( B T ) where t 0.99 refers to the time taken for 1% decomposition to occur at each temperature in minutes, T (°C) represents the temperature, and A and B refer to constant parameters, which are summarized in Table S1, of which the parameters of [EMIM][TfO] and [EMIM][TCB] were missed. The onset decomposition temperatures of [OMIM][BF 4 ], [EMIM][TfO], N -butylpyridinium tetrafluoroborate, and [EMIM][TCB] were 397, 397.5, 373, and 375 °C, respectively. , The onset decomposition temperature of [OMIM][BF 4 ] was similar to that of [EMIM][TfO], and that of N -butylpyridinium tetrafluoroborate was similar to that of [EMIM][TCB]; therefore, the approximate estimation method was used for calculation of [EMIM][TfO] and [EMIM][TCB]. The liquid holding capacity of ILs in the distillation column was provided by the hydraulic check of the distillation column.…”

“…[TCB] were 397, 397.5, 373, and 375 °C, respectively. 59,60 The onset decomposition temperature of [OMIM][BF 4 ] was similar to that of [EMIM][TfO], and that of N-butylpyridinium tetrafluoroborate was similar to that of [EMIM][TCB]; therefore, the approximate estimation method was used for calculation of [EMIM]-[TfO] and [EMIM][TCB]. The liquid holding capacity of ILs in the distillation column was provided by the hydraulic check of the distillation column.…”