Multimetallic heterogeneous catalyst

As mentioned before, heterogeneous catalysts (except unsupported ones) consist of mono-/bi-/multimetallic... 

In liquid-phase oxidations, POMs can be used as efficient homogeneous and heterogeneous catalysts in combination with the environment-friendly oxidants such as H2O2 and O2. Especially, the POM catalysts with multimetallic active sites show unique oxidation reactions in comparison with the conventional monometallic complexes. The activities and selectivities for the selective oxidation by multimetallic active sites of POMs can largely be enhanced by the cooperative activation of oxidants, simultaneous activation of oxidants and substrates, ... 

However, some other aspects of the chemistry of ti bonded metal BT and DBT complexes could be of importance in connection with HDS. It is now known, for instance, that 4-methyl- and 4,6-dimethyldibenzothiophene are desulfurized mainly through prior hydrogenation of one or both of the arene rings [46, 112-115], and therefore the study of model ti -DBT complexes could be of use in developing efficient homogeneous, heterogeneous or hybrid catalysts for reducing the arene moieties in this type of molecule either as a pretreatment for conventional HDS, or as an added functionality in novel multimetallic catalyst formulations this possibility is further discussed in Chapter 3. 

Apart from these academic model catalysts a more practical field of application for nanostructured metal colloids in heterogeneous catalysis resides in the manufacture of fine chemicals. ] Bimetallic, even multimetallic precursors on various supports, eventually promoted by dopants, have been successfully tested as highly active, selective catalysts of remarkable durability. For example, surfactant-stabilized Pd-Pt-charcoal catalysts, promoted by bismuth have been shown to be superior catalysts for the carbohydrate oxidation reaction shown in Eq. (1) ... 

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