Solid catalyst with ionic liquid layer system

Silica gels have been used in recent years as supports for the immobihzation of ILs in order to improve their applicability and reusabiHty in industrially important catalytic processes. In particular, there have also been numerous studies in which silica gels are used as inorganic supports for the development of recyclable and efficient catalytic systems based on supported ILs, namely, supported ionic hquid phase (SILP) catalysts [57-59], supported ionic liquid catalysts (SILCs) [60-62], and solid catalysts with ionic liquid layers (SCILL) [63]. 

A rather new concept for biphasic reactions with ionic liquids is the supported ionic liquid phase (SILP) concept [115]. The SILP catalyst consists of a dissolved homogeneous catalyst in ionic liquid, which covers a highly porous support material (Fig. 41.13). Based on the surface area of the solid support and the amount of the ionic liquid medium, an average ionic liquid layer thickness of between 2 and 10 A can be estimated. This means that the mass transfer limitations in the fluid/ionic liquid system are greatly reduced. Furthermore, the amount of ionic liquid required in these systems is very small, and the reaction can be carried in classical fixed-bed reactors. 

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