Microemulsion vs Traditional Techniques

4 Microemulsion vs Traditional Techniques. - The performance of catalysts prepared by microemulsion has been studied in heterogeneous catalytic processes. Here we will describe some examples in which catalysts prepared by microemulsion display a performance different from that of catalysts prepared by traditional synthesis routes. 

Fernandez-Garcia et al. have described the synthesis and characterization of Pd/CexZri.x02/Al203 three-way catalysts (TWCs) °° ° by Pd impregnation of a 

Recently, the microemulsion technique has been explored as an alternative route to prepare Cu/ZnO catalysts. The Cu/ZnO catalyst was prepared in a microemulsion system using the oxalate route. In spite of the low surface are and poor Cu dispersion, the catalysts obtained by this procedure, when compared to catalysts prepared by a classical co-impregnation method, were more active in H2 production through partial oxidation of methanol. The authors propose this enhancement in the activity to be due either to the presence of some specific 

Recently, taking advantage of the very narrow size distribution of the metal particles obtained, microemulsion has been used to prepare electrocatalysts for polymer electrolyte membrane fuel cells (PEMFCs) Catalysts containing 40 % Pt Ru (1 1) and 40% Pt Pd (1 1) on charcoal were prepared by mixing aqueous solutions of chloroplatinic acid, ruthenium chloride and palladium chloride with Berol 050 as surfactant in iso-octane. Reduction of the metal salts was complete after addition of hydrazine. In order to support the particles, the microemulsion was destabilised with tetrahydrofurane in the presence of charcoal. Both isolated particles in the range of 2-5 nm and aggregates of about 20 nm were detected by transmission electron microscopy. The electrochemical performance of membrane electrode assemblies, MEAs, prepared using this catalyst was comparable to that of the MEAs prepared with a commercial catalyst. 

Liu et al. have prepared PtRu/C catalysts from microemulsions and emulsions . Their results show how particles prepared from microemulsions displayed a lower particle size than the emulsion counterparts. 

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