Interactions of [BMIM][BF₄] with Metal Oxides and Their Consequences on Stability Limits

Abstract

Interactions between 1-n-butyl-3-methylimidazolium tetrafluoroborate, [BMIM]­[BF4], and high-surface-area metal oxides, SiO2, TiO2, Fe2O3, ZnO, γ-Al2O3, CeO2, MgO, and La2O3, covering a wide range of point of zero charges (PZC), from pH = 2 to 11, were investigated by combining infrared (IR) spectroscopy with density functional theory (DFT) calculations. The shifts in spectroscopic features of the ionic liquid (IL) upon coating different metal oxides were evaluated to elucidate the interactions between IL and metal oxides as a function of surface acidity. Consequences of these interactions on the short- and long-term thermal stability limits as well as the apparent activation energy (E a) and rate constant for thermal decomposition of the supported IL were evaluated. Results showed that stability limits and E a of the IL on each metal oxide significantly decrease with increasing PZC of the metal oxide. Results presented here indicate that the surface acidity strongly controls the IL–surface interactions, which determine the material properties, such as thermal stability. Elucidation of these effects offers opportunities for rational design of materials which include direct interactions of ILs with metal oxides, such as solid catalysts with ionic liquid layer (SCILL), and supported ionic liquid phase (SILP) catalysts for catalysis applications or supported ionic liquid membranes (SILM) for separation applications.

A Bibliometric Analysis of Research on Supported Ionic Liquid Membranes during the 1995–2015 Period: Study of the Main Applications and Trending Topics

“…At least one ion has a delocalized charge and one component is organic, which prevents the formation of a stable crystal lattice. Each different ion pair combination results in a different set of physicochemical properties, hence they are considered as “designer solvents” [ 5 ]. Consequently, ILs can be formulated to be task specific and therefore, can be tailor made.…”

Improving Gas Separation Performance of ZIF-8 by [BMIM][BF4] Incorporation: Interactions and Their Consequences on Performance

“…reporting the most stable conformer of [BMIM][BF 4 ],30 however ILs may have more than one stable conformer and depending on the conformers preferred inside the MOF cage, there may be different shifts observed in IR features. We suggest that detailed DFT-based studies can provide valuable information in the way of revealing these interactions between the ILs and MOFs in such IL-incorporated MOF materials in deep detail 23.…”

Experimental investigations on the regeneration of desulfurized 1‐butyl‐3‐methylimidazolium tetrachloroferrate [Bmim][FeCl4] and 1‐butyl‐3‐methylimidazolium thiocyanate [Bmim][SCN] ionic liquids: A raman spectroscopic study

“…this sudden loss in the weight can be directed to the rupture in the main aromatic ring of the ionic liquid, that is, [Bmim][SCN] . This sudden heavy loss in the weight of the ionic liquid that is, [Bmim][SCN] can be directed to the weak intermolecular interaction, which plays a significant role in the enhancement of the thermal stability of the ionic liquids under harsh thermal conditions …”