Solid catalysts with ionic liquid layer

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]. 

Figure 4.1 Major types of supported ionic liquids multilayer ionic liquid film (supported ionic liquid phase SILP) type A, coated heterogeneous catalyst (solid catalyst with ionic liquid layer SCILL) type B, covalently bound monolayer (supported ionic liquid SIL) type C.

SCILL solid catalyst with ionic liquid layer... 

If supported ILs are used for catalysis (supported ionic liquid phase, SILP solid catalyst with ionic liquid layer, SCILL), the layer thickness (Sj ) is small, mostly only a few layers or even only a monolayer, that is, 1 run. For a conservative estimation of the characteristic time of diffusion, we assume a value of 10 run, which is in the order of magnitude of the diameter of a mesopore. The characteristic... 

Kernchen, U., Etzold, B., Korth, W., and Jess, A. (2007) Solid Catalyst with Ionic Liquid Layer (SCILL) - a new concept to improve selectivity illustrated by hydrogenation of cyclooctadiene. Chem. Eng. Technol, 30, 985-994. 

Solid Catalysts with Ionic Liquid Layer (SCILL)... 

Ionic Hquids (ILs) are low melting salts (<100 °C) and represent a promising solvent class, for example, for homogeneous two-phase catalysis [7-9] and extractions [10-12]. These and other appHcations of ILs have been reviewed in a number of papers [7, 13-16]. One of the main reasons that ILs have gained interest both in academia and in industry is that they have an extremely low vapor pressure [17, 18], which makes them attractive as alternative reaction media for homogeneous (two-phase) and heterogeneous catalysis [19, 20]. This paper focuses on the concept of a solid catalyst with ionic liquid layer (SCILL) as a novel method to improve the selectivity of heterogeneous catalysts. 

As for the SILP and solid catalysts with ionic liquid layer (SCILL) applications described in this book, aU these applications aim for using the applied IL in the most effective way. This intended efficiency in IL use is understandable from the fact that synthesis and purification of most I Ls is much more demanding in chemicals, steps, energy, and cost than - for example - the production of the same amount of a common volatile solvenL such as, for example, methanol. Thus, an application that builds on some unique property profile of an IL becomes economically and technically more attractive if the same desired effect can be realized with smaller amounts of ILs. This raises the important question about the minimum amount... 

Jess, A., Kern, C. and Korth, W, Solid catalyst with ionic liquid layer (SCILL) - A concept to improve the selectivity of selective liquid and gas phase hydrogenations. Oil Gas Eur. Mag. 38(1), 38-45 (2012). 

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