Catalysis supported liquid phase

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. 

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. 

Selective oxidation of ethylene to acetaldehyde was carried out over carbon-supported Pd and Pt membrane catalysts.1322 The concept of supported liquid-phase catalysis was also successfully applied in the Wacker oxidation.1323 The Wacker reaction can be performed in alcohol-supercritical C02.1324 C02 as cosolvent accelerates reaction rates and remarkably affects the selectivity towards methyl ketone in the presence of an alcohol. 

Abbreviations AD, asymmetric dihydroxylation BPY, 2,2 -bipyridine DMTACN, 1,4-dimethyl-l,4,7-triazacyclonane EBHP, ethylbenzene hydroperoxide ee, enantiomeric excess HAP, hydroxyapatite LDH, layered double hydroxide or hydrotalcite-type structure mCPBA, meta-chloroperbenzoic acid MTO, methyltrioxorhenium NMO, A-methylmorpholine-A-oxide OMS, octahedral molecular sieve Pc, phthalocyanine phen, 1,10-phenantroline PILC, pillared clay PBI, polybenzimidazole PI, polyimide Por, porphyrin PPNO, 4-phenylpyridine-A-oxide PS, polystyrene PVP, polyvinylpyridine SLPC, supported liquid-phase catalysis f-BuOOH, tertiary butylhydroperoxide TEMPO, 2,2,6,6-tetramethyl-l-piperdinyloxy TEOS, tetraethoxysilane TS-1, titanium silicalite 1 XPS, X-ray photoelectron spectroscopy. 

Reilly, C. R., Lerou, J. J., Supported liquid phase catalysis in selective oxidation, Catal Today, 433, 1998... 

Although still confined to laboratory scale, aqueous-biphase catalysis (cf. Section 3.1.1.1) and related variations such as supported liquid-phase catalysis (cf. Section 3.1.1.3.5) are emerging as viable techniques for the deep HDS of refined fuels [15]. 

R. Neumann, M. Cohen, Solvent-anchored supported liquid phase catalysis Polyoxometalate-catalyzed oxidations, Angew. Chem. Int. Ed. Engl. 36 (1997) 1738. 

In supported-liquid-phase catalysis (SLPC) a metal complex is dissolved in a thin film of polar solvent (usually water) adsorbed on a high-surface-area hydrophilic support such as silica or controlled-pore glasses [40]. The resulting catalyst is placed in contact with a water-immiscible liquid phase containing the reactants and the reaction occurs at the aqueous-organic interface. The catalyst can be recovered by filtration. 

Hydroformylation of Olefins in Supported Liquid-phase Catalysis... 

Supported liquid-phase catalysis,in which the catalyst is dissolved in a small volume of solvent, adsorbed on, usually, a hydrophilic solid, seeks to resolve issues associated with substrate solubility in multi-phase catalysis and performance/catalyst leaching in supported catalysis reports on the hydroformylation of long-chain alkenes under both supported aqueous phase and supported ionic liquid-phase regimes have been reported. 

Supported aqueous-phase catalysts (SAPC) can be seen as a special case of adsorption, whereby a water-soluble catalyst dissolved in a very polar solvent is adsorbed on a hydrophilic support forming a water film on the inner surface of the support [30,31]. In the case of supported liquid-phase catalysis (SLPC),the water film on the inner surface is replaced by a solvent of low vapor pressure (e.g.jphthalic acid esters) [2]. The reaction itself takes place in the supportedUq-uid or at the interface of the supported liquid film, or in the gas phase or organic phase when dealing with SLPC or SAPC, respectively. The use of SLPC catalysts is generally restricted to the synthesis of low-boiling compounds. 

Figure 6 Schematic representation of supported liquid-phase catalysis involving ILs. Adapted from ref. 167.

Figure 2.14 Schematic presentation of the concept of supported liquid phase catalysis. (Adapted from Ref. [16], Figure 4.22 Copyright 2012, Wiley-VCFI GmbH Co. KGa/V.)...

Simultaneous absorption/desorption with reaction (including "supported liquid phase catalysis")... 

Villadsen,J. and H.Livberg. "Supported liquid phase catalysis" (Proceedings of NATO ASI on "Multiphase Reactors", Portugal 19801 ... 

Scheme 9.14 Solvent-anchored supported liquid phase catalysis Silica—PEC/PPC-H5PV2Mo-]o04o-...

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