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This work provides a critical review of the progress in the use of Room Temperature Ionic Liquids (RTILs) as Proton Exchange Membrane (PEM) electrolytes in Fuel Cells (FCs). It is well-known that for an efficient early commercialisation of this technology it is necessary to develop a proton exchange membrane with high proton conductivity without water dependency capable of working at temperatures above 100 ºC. The use of ionic liquids as electrolytes in electrochemical devices is an emerging field due to their high conductivity, as well as their thermal, chemical and electrochemical stability under anhydrous conditions. This paper attempts to give a general overview of the state-of-the-art, identifies the key factors for future research and summarises the recent progress in the use of ionic liquids as an innovative type of PEMs.

In this paper, we investigate the molecular dynamics and ions transport properties of polymerized imidazolium-based protic ionic liquid [HSO 3 −BVIm][OTf]a new material with potential applications in energy storage and electrochemical devices. The results of dielectric measurements, analyzed in modulus M*(f) and conductivity σ*(f) formalisms, combined with temperature-modulated differential scanning calorimetry experiments, have revealed a fundamental difference between the conducting properties of the examined polymer membrane and its low-molecular weight counterpart. Our findings indicated a strong decoupling between conductivity relaxation times τ σ (related to the ions migration through the polymer matrix) and segmental dynamics when the ionic transport is controlled by fast proton hopping through the dense hydrogen-bond network. Finally, we also discuss, for the first time, the effect of water content on the glass transition temperature value, relation between the charge and mass diffusion, reflected in the decoupling phenomenon, and the conductivity mechanism of examined poly[HSO 3 −BVIm][OTf].

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Designed room temperature ionic liquids (RTILs) containing silver salt are presented as reactive media in separating propylene/propane gas mixtures. Solubilities of propylene and propane in the reactive media, silver tetrafluoroborate (AgBF 4 ) dissolved in 1-butyl-3-methylimidazolium tetrafluoroborate (BmimBF 4 ) and N-butyl-4-methylpyridinium tetrafluoroborate (BmpyBF 4 ), were investigated as a function of silver ion concentration, temperature, and pressure. Equilibrium data were obtained working in a temperature range between 278 and 318 K and at pressures up to 6 bar. Propylene absorption was chemically enhanced in the silver-based RTILs and was considerably higher than that in the standard RTILs. Absorption of propane in the silver-based RTILs is based on physical interactions only. A simple mathematical model based on the formation of complex species with different stoichiometry has been developed in order to describe the total propylene absorption, and the model was validated with experimental data obtained working with different concentrations of silver salt (between 0.1 and 1 M). The model parameters, equilibrium constants (K Eq,1 f(T) and K Eq,2 f(T)), and enthalpies of complexation (∆H r,1 , ∆H r,2 ) were obtained. Thermal stability of the silver ions was analyzed and to be found dependent on the silver salt concentration. Complete regeneration of the reaction media was possible at a temperature of 313 K and 20 mbar of pressure.

Light olefins are mainly produced by naphtha steam cracking, which is among the more energy intensive processes in the petrochemical industry. To save energy, some alternatives have been proposed to partially replace or combine with cryogenic distillation the conventional technology to separate olefins and paraffins. Within this aim, facilitated transport membranes, mainly with Ag + cations as selective carriers, have received great attention owing to the high selectivity and permeance provided. However, to be used industrially, the undesirable instability associated with the Ag + cation should be considered. Poisonous agents and polymer membrane materials are sources of Ag + deactivation. In recent years, great achievements on the separation performance have been reported, but the current challenge is to maintain the selectivity in long-term separation processes. This work presents a critical analysis of the potential causes of Ag + deactivation and points out some alternatives that have been proposed to overcome the hurdle. This review highlights and critically analyses some perspectives of the ongoing development and application of facilitated transport membranes.