Carbon using inorganic supports

Table 2.3 Examples of heterogeneous asymmetric carbon-carbon and carbon-heteroatom bond formation using inorganic supports. 

Carbon nanotubes (CNTs) are a set of materials with different structures and properties. They are among the most important materials of modern nanoscience and nanotechnology field. They combine inorganic, organic, bio-organic, coUoidal, and polymeric chemistry and are chemically inert. They are insoluble in any solvent and their chemistry is in a key position toward interdisciphnary applications, for example, use as supports for catalysts and catalytic membranes [20, 21]. 

Since 1985, several thousands of publications have appeared on complexes that are active as catalysts in the addition of carbon monoxide in reactions such as carbonylation of alcohols, hydroformylation, isocyanate formation, polyketone formation, etc. It will therefore be impossible within the scope of this chapter to review all these reports. In many instances we will refer to recent review articles and discuss only the results of the last few years. Second, we will focus on those reports that have made use explicitly of coordination complexes, rather than in situ prepared catalysts. Work not containing identified complexes but related to publications discussing well-defined complexes is often mentioned by their reference only. Metal salts used as precursors on inorganic supports are often less well defined and most reports on these will not be mentioned. 

A variety of industrial catalytic processes employ small metal-particle catalysts on porous inorganic supports. The particle sizes are increasingly in the nanometre size range which gives rise to nanocatalysts. As described in chapter 1, commonly used supports are ceramic oxides, like alumina and silica, or carbon. Metal (or metallic) catalysts in catalytic technologies contain a high dispersion of nanoscopic metal particles on ceramic oxide or carbon supports. This is to maximize the surface area with a minimum amount of metal for catalytic reactions. It is desirable to have all of the metal exposed to reactants. 

The most commonly used column support materials are made from diatomite. Other materials include sand. Teflon, inorganic salts, glass beads, porous layer beads, porous polymers, carbon blacks, etc. We will discuss the diatomite supports in some detail and additional information may be obtained in Chapter 3. 

Carbon Nanotubes (CNTs) Use of CNTs as inorganic support, focus on electrochemistry as detection method, organic groups and biomolecules as functionalization materials, and their application in sensing. 

We pioneered the use a noncoherent IR radiation for a formation of the metal -carbon film on a surface of porous inorganic support. In this research the film was obtained from a mixture PAN and ammonium perrhenate solutions in dimethylformamide on the surface of the porous stainless steel. 

Nhut, J.-M., Pesant, L., Tessonnier, J.-P, Wme, G., Guille, J., Pham-Huua, C., and Ledoux, M.-J. 2003. Mesoporous carbon nanotubes for use as support in catalysis and as nanosized reactors for one-dimensional inorganic material synthesis. Appl. Catal. A Gen. 254 345-363. 

Research on the immobilization of metal complexes using carbon materials is scarce compared with inorganic supports, such as zeolites, silicas, and clay-based materials [1-10]. Nevertheless, carbon materials are unique supports, as they can provide a variety of surface groups at the edges and/or defects of graphene sheets that can be tailored by adequate thermal or chemical treatments, besides the inherent chemical-physical reactivity associated with the graphene sheets themselves, which are hydrophobic, have low polarity, and have a rich n-electron density [13-15]. This can lead to a huge diversity of methods for immobilization of molecular species. 

Different inorganic materials have been used as supports in SAPC glass beads of controlled pore size [6,14—17, 24, 39—42,44,45, 53] porous [11,15,18,19, 21, 23, 28-32, 35, 36, 38, 39, 43, 48, 49] and nonporous [28, 33, 48] silica nanoparticles synthetic phosphate [27] carbon [39], and alumina [15,39]. It was shown that glass beads, siKca, and synthetic phosphate gave the best performance. All these supports have a high specific surface with an average diameter of the pores, in the case of porous supports, between 60 and 345 A. The use of chitosan as a natural polymeric support of SAP catalysts for the synthesis of fine chemicals has been reported recently [54]. 

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