Heterogeneous catalysts, characterization

Heterogeneous Catalysis by Metal Clusters. - Present activity in this area reflects the view that supported metal clusters could form the basis of a new generation of heterogeneous catalysts. Characterization of such materials, especially under reaction conditions, will be difficult. Such catalysts will be valuable if they exhibit activities and selectivities that differ from those afforded by conventionally prepared catalysts unfortunately, it is a deficiency of much of the work so far reported that such comparisons have not been made. However, evidence has recently become available that shows that cluster-derived heterogeneous catalysts may exhibit distinctive behaviour. 

Characterization of Heterogeneous Catalysts, edited by Francis Delannay... 

In Chapter 1 we emphasized that the properties of a heterogeneous catalyst surface are determined by its composition and structure on the atomic scale. Hence, from a fundamental point of view, the ultimate goal of catalyst characterization should be to examine the surface atom by atom under the reaction conditions under which the catalyst operates, i.e. in situ. However, a catalyst often consists of small particles of metal, oxide, or sulfide on a support material. Chemical promoters may have been added to the catalyst to optimize its activity and/or selectivity, and structural promoters may have been incorporated to improve the mechanical properties and stabilize the particles against sintering. As a result, a heterogeneous catalyst can be quite complex. Moreover, the state of the catalytic surface generally depends on the conditions under which it is used. 

This complex and structurally related molecules served as a functional homogeneous model system for commercially used heterogeneous catalysts based on chromium (e.g. Cp2Cr on silica - Union Carbide catalyst). The kinetics of the polymerization have been studied to elucidate mechanistic features of the catalysis and in order to characterize the potential energy surface of the catalytic reaction. 

Many different topics are involved in the study of metallic nanoparticles and many fundamental issues can be present for example, which is the infiuence of the nanoparticle size, shape and composition on the chemical activity of heterogeneous catalysts Or, considering another problem, at what size does a small particle behave like the bulk material, for example, changing from an insulator to a semiconductor [9-12] An enormous amount of literature is published on metallic nanoclusters this review is focusing on the relevant problem concerning the characterization of metallic nanosized materials from the morphological and... 

In heterogeneous catalysis catalyst characterization plays an important role. It is fair to state that improved characterization techniques have been the major drive towards the development of heterogeneous catalysis as a mature technology. 

Topspe, H. (2003) Developments in operando studies and in situ characterization of heterogeneous catalysts, J. Catal., 216, 155. 

Barron, L. D., and Vrbancich, J. Natural Vibrational Raman Optical Activity. 123, 151-182 (1984). Bazin, D., Dexpert, H., and Lagarde, P. Characterization of Heterogeneous Catalysts The EXAFS Tool, 145, 69-80 (1987). 

The effectiveness of zeolites in catalysis and separation can often be improved by the textural and chemical properties of the matrices in which they are imbedded. Chitosan gels issued from renewable resources are already used as supports for the preparation of heterogeneous catalysts in the form of colloids, flakes or gel beads [1, 2], In this study we present several methods for the incorporation of zeolites in chitosan matrices and characterize the synergic effect of the components on the properties of the composite. 

Heterogeneous Catalysis Aim of Catalyst Characterization Spectroscopic Techniques Research Strategies... 

J.L.G. Fierro (Ed.), Spectroscopic Characterization of Heterogeneous Catalysts, Elsevier, Amsterdam, 1990. 

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