Multimetallic

Dehydrogenation method and nonacidic multimetallic catalytic composite for use therein Catalyst development Pt, Co, U 77... 

Hydrocarbon dehydrogenation with a multimetallic catalytic composite Catalyst development Pt-Re-Ru-Li-Cl 79... 

Dehydrogenation process utilizing multimetallic catalytic composite Catalyst development catalyst contains Pt and Ge 82... 

Hydrocarbon conversion with acidic multimetallic catalytic composite Production of catalysts 87... 

These processes are very rapid and allow the preparation of inorganic supports in one step. This technique allows large-scale manufacturing of supports such as titania, fumed silica, and aluminas. Sometimes the properties of the material differ from the conventional preparation routes and make this approach unique. Multicomponent systems can be also prepared, either by multimetallic solutions or by using a two-nozzle system fed with monometallic solutions [22]. The as-prepared powder can be directly deposited onto substrates, and the process is termed combustion chemical vapor deposition [23]. 

Alloys or multimetallic catalysts are not only commercially important but they are also an attractive object for scientific studies. In the recent past these studies helped to identify some factors which determine the activity and - mainly - the selectivity of metal catalysts (1-5). 

The state of the knowledge is at the moment such that still in each particular case, the investigator should analyse and establish experimentally how important are, relative to each other, the effects 1) and 2) for the activity and the selectivity of a given multimetallic catalyst. It is an historical experience that when the explanation of the data is not immediately obvious, the authors offer as an "explanation" "an electronic (ligand) effect" (7). In this way it happened that the effect sub 1) has been most frequently proven to operate, while the effect sub 2) is the most frequently postulated... 

What is the stability of such a bimetallic electrode, as well as that of other bimetallic and multimetallic electrodes, which exhibit high activity for methanol oxidation ... 

The extensive state of knowledge of the electrooxidation of methanol, as presented in this section, offers prospects of tailoring new multimetallic... 

Since 1976 until present time Toshima-t5q)e nanocolloids always had a major impact on catalysis and electrocatalysis at nanoparticle surfaces [47,210-213,398-407]. The main advantages of these products lie in the efficient control of the inner structure and morphology especially of bimetallic and even multimetallic catalyst systems. 

In order to realize the precise control of core/shell structures of small bimetallic nanoparticles, some problems have to be overcome. For example, one problem is that the oxidation of the preformed metal core often takes place by the metal ions for making the shell when the metal ions have a high-redox potential, and large islands of shell metal are produced on the preformed metal core. Therefore, we previously developed a so-called hydrogen-sacrificial protective strategy to prepare the bimetallic nanoparticles in the size range 1.5-5.5nm with controllable core/shell structures [132]. The strategy can be extended to other systems of bi- or multimetallic nanoparticles. 

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

Overall, this chapter aimed to emphasize and demonstrate the great potential of utilizing a multidisciplinary approach to bimetallic systems that combines computational methods with a number of highly sophisticated in situ and ex situ surface-sensitive techniques at electrified solid-liquid interfaces. Advances in the understanding of fundamental properties that govern catalytic processes at well-defined multimetallic... 

However, in the case of multimetallic catalysts, the problem of the stability of the surface layer is cmcial. Preferential dissolution of one metal is possible, leading to a modification of the nature and therefore the properties of the electrocatalyst. Changes in the size and crystal structure of nanoparticles are also possible, and should be checked. All these problems of ageing are crucial for applications in fuel cells. 

Meso substitution of porphyrines to give tetraazaporphyrines, so-called porphyrazines, modulates the electronic character of the macrocycle. While porphyrazines have received considerably less attention than porphyrines over many years, this has changed due to the development of efficient syntheses of soluble derivatives.1 6-1809 Also, various porphyrazines (and phtalocyanines) with peripheral groups for metal ion coordination have been prepared and used for the construction of multimetallic complexes.1806 Ni porphyrazines (695) typically show absorptions spectra with a strong Q band at around 615nm. 

Figure 3 Three representative Fe-S multimetallic cores observed in iron-sulfur proteins...

Grosso, D. Boissiere, C. Smarsly, B. Brezesinski, T. Pinna, N. Albouy, P. A. Amenitsch, H. Antonietti, M. Sanchez, C. 2004. Periodically ordered nanoscale islands and mesoporous films composed of nanocrystalline multimetallic oxides. 

On the one hand, this mechanistic study represents the culmination of many preceding studies. On the other hand, this, together with several other recent developments, represents a new generation of organozirconium chemistry characterized by (i) Zr catalysis, (ii) bimetallic and multimetallic systems, in which bi- and multimetallic interplay is significant, and (iii) significant roles of various 0-bond metatheses. 

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