Inorganic oxides surface area aluminas

Traditional adsorbents such as sihca [7631 -86-9] Si02 activated alumina [1318-23-6] AI2O2 and activated carbon [7440-44-0], C, exhibit large surface areas and micropore volumes. The surface chemical properties of these adsorbents make them potentially useful for separations by molecular class. However, the micropore size distribution is fairly broad for these materials (45). This characteristic makes them unsuitable for use in separations in which steric hindrance can potentially be exploited (see Aluminum compounds, aluminum oxide (ALUMINA) Silicon compounds, synthetic inorganic silicates). 

Natural Fe oxides have also been used for water purification. In a laboratory study, a natural ferrihydrite (surface area of 243 m g ) originating from a ferriferrous acid spring turned out to be capable of removing > 95 % of the inorganic phosphate from water with 0.1 mg P L (WeiE et al., 1992). The so-called Red Mud, a waste product of the alumina industry, containing 330 g Fe/kg was also effective, whereas a tropical soil with 80 g kg Fe was comparatively less so (WeiE et al., 1992a). Nine... 

Inorganic ceramic oxide supports for catalysts, such as alumina and silica, are used extensively in the catalysis industry because they are strong, they can have a range of shapes for different engineering needs and they are economical. They provide high surface areas for catalysis, ranging from 50 to 500 m g and can have pore sizes ranging from 2 to 20 nm in diameter. 

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. 

This is another metal oxide used in thin-layer applications. The chemical formula is AI2O3. On aluminum oxide thin-layers sorption is based on partial positive and negative charges on the surface and any water sorbed thereon. In the manufacturing process aluminum oxide can be made to have a basic surface (pH 9-10), a neutral surface (pH 7-8), or an acidic surface (pH 4-4.5). This allows for a different type of adsorption separation based solely on surface pH. Other properties of the different aluminas available for TLC are shown in Table 2. The different pore size and surface area types will also impart different separation characteristics to these sorbent layers. Layers of this sorbent are available with and without binders both organic and inorganic. A whole range of... 

The first class, inert inorganic sol-gels, are not redox active (e.g., silica, alumina, and zirconia) (113). In the gel form these materials have a large surface area, high ion-exchange capacity (due to surface hydroxyls), and exhibit good adhesion to metal oxide and ceramic supports. 

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