Catalyst supported liquid phase

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... 

The Oxidation of Sulphur Dioxide. - This very important reaction is probably the oldest one in which vanadium catalysts have been used in practice. It is generally assumed that in these catalysts the vanadium is present dissolved in a liquid mixture of alkali metal meta- and/or pyro-sulphates. Villadsen and Livbjerg3 recently reviewed the properties of these supported liquid phase catalysts and showed that a number of questions still remain unanswered. Urbanek et al.la and Kenney75 presented reviews of the catalytic oxidation of S02, considering both the kinetics and problems of industrial reaction design. 

Supported liquid-phase catalysts (SLPCs) combine the salient features of both homogeneous and heterogeneous catalysis for enhanced catalytic and/or process efficiency (337). SLPC catalysts, in which a liquid-phase (homogeneous) catalyst is dispersed within a porous support, have been used in Wacker-type ethylene oxidation for acetaldehyde and vinyl acetate production (337, 338). In the former case, a traditional homogeneous Wacker catalyst (vide supra) consisting of a chlorinated solution of Pd and Cu chlorides retained on a support with monomodal pore size distribution... 

The active phase of the Deacon catalyst is usually assumed to be a complex melt of copper or chromium and alkaline metal chlorides under reaction conditions, which is distributed within the pore network of an inert carrier [42]. Such supported liquid-phase catalysts (SLPC) are eminently suitable for adsorbing large amounts of the reacting components as sorption takes place in a bulk phase and is not restricted to only a limited number of suitable surface sites. The periodic expansion and contraction of the melt as a result of (de) sorption imposes considerable strains on the carrier structure hence, special mechanically robust support materials are needed to withstand such strains and prevent the catalyst crumbling away and disintegrating after a few cycles. In addition, even when it is immobilized on the carrier, the melt is extremely aggressive and resistant materials must be used for reactor construction. 

Alternatively, polar liquids other than water can be used to generate supported liquid-phase catalysts with sulfonated ligands. For example, supported liquid-phase Pd-TPPTS catalysts have been prepared on silica with ethylene glycol as the liquid phase. " ... 

Supported Liquid-phase Catalyst Sandwiched between Two Different Membranes... 

The transitions of supported liquid-phase catalysts (SLPC) and supported aqueous-phase catalysts (SAPC) are dealt with in Section 3.1.1.3, while special aspects of clusters and colloids are discussed in Sections 3.1.1.4 and 3.1.1.5 and those of aqueous-phase, re-immobilized catalysts in Section 3.1.1.6. The combination of heterogeneous catalysis with aqueous (biphasic) techniques is also under investigation, e. g., [209]. 

Adsorption of standard-type homogeneous complexes on supports [90], such as Vaska s complex, is possible but these catalysts clearly cannot be used with solvents that dissolve the complex. These studies, however, have to be seen in the context of supported liquid-phase catalysts. 

Figure 2. Schematic of a supported liquid-phase catalyst [102], The liquid or water...

Solvent-anchored, supported, liquid-phase catalysts... 

An interesting approach to overcome these limits and thus combine the advantages of homogeneous and heterogeneous catalysis is that of supported liquid phase catalysts (SLPC or SLP). In SLPC the organometallic complex active components are dissolved in a small quantity of liquid phase dispersed in the form of an isle or film on the surface of supports. A SLPC has been applied successfully for several chemical transformations [113], particularly in the Wacker-type ethylene oxidation to acetaldehyde and vinyl acetate production by ethylene acetoxylation [114], and in other reactions catalyzed by Pd-complexes such as the Heck reaction [115]. 

Metal complexes have been immobilised in many different ways, e.g. covalent anchoring (by grafting or tethering) to inorganic supports, immobilisation by occlusion in zeolitic micro- or mesopores (ship-in-a-bottle concept), or as supported liquid-phase catalysts [2], In recent reviews the potential of (chiral) metal complexes immobilised by these different methods has been evaluated [3,4,5]. 

Supported liquid phase catalysts A new approach for catalytic oxidation in diesel exhaust particulate emission control. 

The use of a Supported Liquid Phase Catalyst offers an opportunity for continuous removal of soot from diesel exhaust gas. Molten salt mixtures show a higher activity compared to solid metal oxides. This high activity can be ascribed to a better contact between the liquid catalyst and the soot. The contact between soot and catalyst remains intact during oxidation. 

Supported liquid-phase catalysts, porous solids with liquids held in the narrow pores, function even at high temperatures. 

The related supported liquid-phase catalysts consist of traditional support materials such as y-AljOj having micropores filled with solvent and a dissolved catalyst. In small pores, because of the Kelvin effect, the vapor pressure of the solvent is small so that it will remain in the pore as a liquid, even when the catalyst is used at a high temperature in flowing vapor-phase reactants" . These catalysts are active for alkene hydroformy-lation the soluble catalyst can thus be used without the complications of corrosion and difficult separation from products—provided that it is stable (cf. 14.2.4). 

Supported liquid phase catalysts (Rony and Roth 1975 Chan and Rinker 1978 Doraiswamy and Sharma 1984 Arhancet et al. 1990, 1991)... 

Supported liquid-phase catalysts (SLPC) Supported organic-phase (SOP) catalysts Supported aqueous-phase (SAP) catalysts... 

Supported Liquid-phase Hydroformylation. - A potentially attractive alternative to chemically anchored hydroformylation catalysts is the use of supported liquid-phase catalyst (SLPC) systems for gas-phase hydroformyl-ations. The homogeneous catalyst is dissolved in a non-volatile solvent and then condensed in the pores of a support, where the strong negative capillary forces effectively immobilize the catalyst, thereby preventing metal loss. In addition one might expect that the environment of the homogeneous system... 

Supported liquid-phase catalysts. (Rony Livbjerg, Sorensen, and Villadsen [144.145,140].)... 

Dissolution in a high-boiling liquid that is adsorbed on a porous support (supported liquid phase catalysts, SLPC)... 

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