Supported liquid phase

Ionic liquid as active layer in supported liquid phase membranes for gas separation Melin, Wasserscheid, et al. 19, 20... 

Immobilization of catalysts is an important process design feature (see Chapter 9.9). A recent example of catalyst immobilization is the biphasic approach which seems superior to immobilization on solids, as successfully proven in the Ruhrchemie/Rhone Poulenc process for the hydro-formylation of olefins.286 Supported liquid phase catalysis was devised as a method for the immobilization of homogeneous catalysts on solids. When the liquid phase is water, a water-soluble catalyst may be physically bound to the solid. 

An alternative to the supported liquid phase (SLP) method was recently proposed using the same type of solid the supported hydrogen bonded (SHB) catalysts. First demonstrated with the zwitteronic Rh1 catalysts [(sulphos)Rh(cod)] (1) and [(sulphos)Rh(CO)2] (2) (sulphos = 03S(Cr,I I4)CI I2C(CH2PPh2) ). the immobilization procedure is based on the capability of the sulfonate tail of sulphos to link the silanol groups of the support via hydrogen bonds (Figure 12). 

The basic idea of immobilising a catalytically active solution on a solid support to obtain a solid catalyst with homogeneous type selectivity and efficiency is not new. In the late seventies, Scholten [69] and Hjortkjaer [70] described supported liquid phase... 

Poly(ethylene glycol) supported liquid-phase syntheses by both the reaction of (polyethylene glycol (PEG))-supported imines with nitrile oxides, generated in situ from aldoximes, (300) and 1,3-dipolar cycloadditions of nitrile oxide, generated in situ on soluble polymers with a variety of imines (301, 302) have been described. The solid-phase synthesis of 1,2,4-oxadiazolines via cycloaddition of nitrile oxide generated in situ on solid support with imines has also been elaborated (303). These syntheses of 1,2,4-oxadiazolines provide a library of 1,2,4-oxadiazolines in good yields and purity. 

Haldor Topspe s fixed-bed alkylation (FBA ) technology is a compromise between liquid and solid acid-based processes. It applies a supported liquid-phase catalyst in which liquid triflic (trifluoromethanesulfonic) acid is supported on a porous material (206,241). The acid in the bed is concentrated in a well-defined catalyst zone, in which all the alkylation chemistry takes place at the upstream... 

Sulphuric acid catalysts are not truly heterogeneous catalysts but so-called supported liquid phase (SLP) catalysts, where the oxidation of S02 takes place as a homogeneous reaction in a liquid film covering the internal surface of the support material [2], This was proposed already in 1940 by Frazer and Kirkpatrick [6], who found that the promoting action of the common alkali metals was due to their ability to form relatively low-melting pyrosulphates, which dissolve vanadium oxides, e.g. for potassium... 

SUPPORTED LIQUID-PHASE SYSTEMS IN TRANSITION METAL CATALYSIS... 

Before the 1990s there was little in the literature on multiphasic L-L-S and L-L-L-S systems used for chemical reactions. There is, however, a relatively large volume of work done on other types of multiphasic systems related to the present topic supported liquid-phase catalysis (SL-PC), and gas liquid phase transfer Catalysis (GL-PTC). The common denominator in both cases is the presence of an interfacial liquid layer of a hydrophilic compound between the catalyst and the bulk of the reaction. 

In future research, it may be interesting to combine supported liquid phase (SLP) catalysts or supported aqueous phase (SAP) catalysts [61,62] with SCCO2 as a mobile phase. 

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