The use of ILs as solvents is sometimes coupled with slow kinetics of the reactions due transport difficulties in viscous fluids. Those problems can be mitigated by “supporting” a thin layer of IL on the surface of solid material, so called supported ionic liquid phase (SILP) technology. In this case IL still acts as reaction media, at the same time the transport of the reactants into the thin film and products of the reaction out of it is increased. There are numerous possibilities spanning from this technology. For example, ionic liquid phase can be catalytically active or just serve a means of selective transport of certain species towards catalytically active support. Using ILs in SILP systems brings the following advantages:
- SILP material combines the best of both heterogeneous catalysis and homogenous catalysis worlds. They can be used in fixed-bed and fluidized-bed reactors, but at the same time offer well defined and easy to modify catalytic systems;
- SILP materials do not suffer from the active material loss due to evaporation, because ILs have negligible vapour pressure;
- SILP materials can be used at reduced pressure;
- SILP materials have a high surface area, allowing increased contact between bulk phase and catalytic centres;
- The amount of IL required is reduced in comparison to ordinary solvent uses;
- Having high dissolution ability, ILs afford preparation of multifunctional catalytic systems by combining compounds with different properties. This allows to conduct tandem and multistep processes in controlled environment;
- ILs help to stabilize and protect the surface, allowing wider operation range;
- ILs modify chemical environment around the active sites, providing increase in selectivity in some reactions;
- Being designer solvents, ILs afford the wide selection of material to be adopted for specific requirements of the systems.