SCILL

Scills Syrupus (syrup of squills) From the sea onion (Urginea martima), used as an expectorant, diuretic, and emetic purgative. Its most common use was in the treatment of chronic bronchitis. Beasley gives more than thirty different prescriptions. 

The amount of IL can be reduced further compared to SILP and SCILL systems, in the extreme case, to only a monolayer or islands of IL coating the support [40]. The role of IL in these systems is to transfer a certain functionaUty of the IL to the support surface. 

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]. 

I 4 Synthetic Methodologiesfor Supported Ionic Liquid Materials Type A SILP Type B SCILL Type C SIL... 

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.

A number of synthetic methodologies have been developed in order to synthesize SILP and SCILL-type materials. The simplest of these methods rehes on physisorp-tion in order to generate the material. Various techniques have been developed to disperse the IL evenly onto the supporf s surface. 

In general, this type of catalyst preparation is a simple and fast approach to immobihze an IL onto a porous material, and various materials of Type A, B, and C have been prepared using this methodology. Depending on the size of the rotary evaporator, batches of SILP or SCILL materials between 10 g and 1 kg can be prepared. 

Since freeze-drying is widely used in industry, SILP and SCILL materials can be produced on a multikilogram scale and the process can also be made continuously. 

Vpore,o is the specific pore volume of the uncoated solid (m kg t), and mjg and Vjg are the mass and volume of the IL used to prepare the SILP or SCILL systems. 

To prove this model for the coating process, two systems were analyzed silica -[EMIM][NTf2] (l-ethyl-3-methylirnidazolium bis(trifluoromethylsulfonyl)imide) on porous silica - and an SCILL catalyst (commercial Ni-catalyst) coated with [BMIM][0cS04] (l-butyl-3-methylimidazolium octylsuUate). 

Example II SCILL Catalyst (Commercial Ni catalyst) Coated with [BMIM][OcSOJ I 99... 

BET analysis of the system Ni catalyst and [BMIMKOCSO4] indicates that both the pore volume (meso- and micropores only) and the surface area decrease with increasing filHng degree (Figures 5.3 and 5.4). The values of the total residual pore volume of the SCILL catalysts measured by BET analysis in combination with Hg-porosimetry agree well with calculations based on the IL volume used for the SCILL catalysts and on the initial pore volume [2, 3]. 

It should be noted that in previous pubhcations [2, 3] where the SCILL concept was initially introduced (taking only hydrogenation of cyclooctadiene as example), a different coating model was proposed on the basis of the following assumptions ... 

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... 

To analyze these issues, ambient pressure and H V experiments with two supports were conducted (i) silica (Kieselgel 100, Merck, 0.06-0.2 mm, p 0.71 gcm Ag 335m g lcm g ) was used as example for the SILP-concept, and (ii) a Ni-catalyst for the SCILL-concept (NiSAT G33, Stid-Chemie, 37 wt% Ni on SiOj 6x6mm cylinders p 1.4gcm Aggj- 105 m g 0.38cm g , see... 

For the given value of Cg j, mono.o equals about 90% (Figure 6.17), and the fraction of surface unoccupied is only 10%, that is, on the average each occupied site contains about 1.1 ion pairs. Hence, the amount of ILneededfor an almost complete coverage approximately equals the minimum amount one would expect for adsorption with only one molecular layer. This is important for supported IL systems, especially for SCILL regarding the influence of the IL layer on the selectivity, because the amount needed to cover the surface completely is then relatively small, for example, in the particular case of Cggj 1, mono.o would be only 50%. 

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. 

In the foreground of this chapter is the concept of an SCILL (Figure 14.1), as a method to improve the selectivity of a heterogeneous catalyst. The SCILL concept [52,53], which was claimed as a patent in cooperation with Siid-Chemie [54], was introduced in 2007 [53] and combines some of the strategies described before ... 

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