Selective oxidation materials, categories

Selective oxidation materials fall into two broad categories supported systems and bulk systems. The latter are of more practical relevance although one intermediary system, namely vanadia on titania [92,199-201], is of substantial technical relevance. This system is intermediary as titania may not be considered an inert support but rather as a co-catalysts [202] capable of, for example, delivering lattice oxygen to the surface. The bulk systems [100, 121, 135, 203] all consist of structurally complex oxides such as vanadyl phosphates, molybdates with main group components (BiMo), molybdo-vanadates, molybdo-ferrates and heteropolyacids based on Mo and W (sometimes with a broad variation of chemical composition). The reviews mentioned in Table 1.1 deal with many of these material classes. 

In other respects, we can consider zeohte membranes as pertaining to the ceramic material category. Indeed zeolites are classified for the most part as microporous, crystalline silico-aluminate stmctures with different alumininum/silicon ratios. Thus, the chemical compositions are close to those of ceramic oxide membranes, in particular of microporous silica and alumina membranes. On the other hand, zeohtes are crystalline materials and they have a structural porosity very different from microporous amorphous silica [124]. Zeohte membranes are well adapted to the separation of gases, in particular H2 from hydrocarbons, but these membranes are not very selective for the separation of mixtures of noncondensable gases. 

The use of coordination compounds in SCFs is rather larger than one might initially expect [1]. The major applications can be divided into two broad categories (1) the transport of metals, which includes selective extraction, deposition of metal and oxide films and impregnation of metals as a route to composite materials and (2) synthesis and reactions, which covers a wide range of topics from the synthesis of oxides and other solid state materials to the reactions of organometallic compounds. This chapter focuses on the synthesis of organometallic compounds because this is the area where the majority of the new experimental techniques have been developed. The chapter complements chapter 3.1 and 3.2 which cover, respectively, vibrational and NMR spectroscopy, because IR spectroscopy, and to a lesser extent NMR, have been key tools in the exploration of this chemistry. 

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