Surface Science and Model Catalysis with Ionic Liquid‐Modified Materials

Abstract

Materials making use of thin ionic liquid (IL) films as support-modifying functional layer open up a variety of new possibilities in heterogeneous catalysis, which range from the tailoring of gas-surface interactions to the immobilization of molecularly defined reactive sites. The present report reviews recent progress towards an understanding of "supported ionic liquid phase (SILP)" and "solid catalysts with ionic liquid layer (SCILL)" materials at the microscopic level, using a surface science and model catalysis type of approach. Thin film IL systems can be prepared not only ex-situ, but also in-situ under ultrahigh vacuum (UHV) conditions using atomically well-defined surfaces as substrates, for example by physical vapor deposition (PVD). Due to their low vapor pressure, these systems can be studied in UHV using the full spectrum of surface science techniques. We discuss general strategies and considerations of this approach and exemplify the information available from complementary methods, specifically photoelectron spectroscopy and surface vibrational spectroscopy.

Surface Enrichment in Equimolar Mixtures of Non‐Functionalized and Functionalized Imidazolium‐Based Ionic Liquids

“…Neat ionic liquids (ILs) have been studied extensively since they are promising candidates for different applications,1 e. g. in the fields of catalysis,2, 3, 4 fuel cells,5,6 lithium ion batteries,7, 8, 9 solvents,10,11 lubricants,12,13 sensors,14,15 and gas separation technologies,15, 16, 17 to name only a few. In many of these applications, the surface of the IL plays a decisive role, because it is its interface to the environment.…”

Metal Nanoparticles/Ionic Liquid/Cellulose: Polymeric Membrane for Hydrogenation Reactions

“…Supported Ionic Liquid Phase (SILP) is emerging as an interesting protocol for the immobilization of transition metal catalysts since it may combine the advantages of ionic liquids (IL) with those of heterogeneous support materials [15][16][17] . In comparison to traditional liquid-liquid biphasic systems, higher catalytic activity and lower metal leaching can be achieved by appropriately tuning the experimental conditions [15,[18][19][20][21][22] .…”

“…In comparison to traditional liquid-liquid biphasic systems, higher catalytic activity and lower metal leaching can be achieved by appropriately tuning the experimental conditions [15,[18][19][20][21][22] . These materials are prepared by the covalent attachment of IL to the support surface or by simply depositing the IL phases containing catalytically active species, usually transition metal complexes [20] or, more rarely, metal nanoparticles [23,24] on the surface of the support, which is usually a silica or polymeric material.…”

Synthesis and Characterization of Imidazolium Perrhenate Ionic Liquids

“…Pioneering contributions came from several groups [14 -18] and many others joined in quickly to unravel a seemingly novel and, as it appears, still today largely undiscovered area of chemistry [19 -21]. Furthermore, studies of ILs and SILPs (Supported Ionic Liquid Phases) [22] as reaction media for two-or multi-phase-catalyzed reactions made applications of ILs an additional and very prominent research area. In some cases, ILs have already found applications in industrial catalytic processes [23].…”