Porous silicas

Particle Porous spherical silica Porous spherical silica... 

Fig. 4. Data of Auroy et al. [25] on polydimethyl-siloxane chains covalently grafted in the interior of a silica porous medium. L is the measured layer thickness from neutron scattering d is the average spacing per chain from the grafting density. The format of the plot is suggested by Eq. 5. The linearity of that relation is seen in these data...

Oxides are widely used as supports. The major examples are silica (porous Si02), alumina (porous AI2O3), and zeolites. Oxides are also u.sed as catalysts. In bulk chemistry they are... 

Figure 2.15 Separation of a mixture of saturated and unsaturated hydrocarbons on a 50 m x 0.32 mm fused silica porous-layer open tubular column coated with alumina modified wl potassium chloride. The separation was performed by temperature programming from 70 to 200°C at 3 C/mln. (Reproduced with permission fr

Although micro- and not mesoporous but worth mentioning in any case is a new class of materials in this evolution series of porous silica-based hybrid materials, the so-called ZOLs (zeolites with organic group as lattice). As we will see, many studies in the past focused on the organic functionalization of amorphous silica porous... 

Common industrial inorganic supports are [14] silica, porous glass, alumina, zeolites, ceramics, Aerosil, and glass balls. Prior to its use the porous silica glass, for instance, must be modified as shown in Eq. 12 with amino alkoxy silanes [141. 

A conventional pulse catalytic microreactor was used with 15-65 mg of the catalyst for the cumene runs and 65 mg for the 2,3-dimethylbutane runs. The catalyst was held between 2 small plugs of borosilicate glass wool in a 5-mm ID diameter borosilicate reactor. In some experiments, the catalyst was diluted with 96% silica porous glass powder. The helium gas was purified by passage through alumina kept at liquid nitrogen temperature. The reaction temperature was measured by a thermocouple located adjacent to the reactor. The catalyst was pretreated at the desired temperature for 16 hours in a stream of helium. The products were analyzed with a dioctyl phthalate gas chromatography column at llO C. 

A few publications have reported the permeation of capillary condensate in mesoporous materials. Caiman and Raal [14], measured permeability of CFiCb in Linde silica porous plugs at 240 and 251.5 K. Lee and Hwang [15], measured freon and water vapor permeabilities on vycor membranes. These permeabilities were found to exhibit maxima at relative pressures around 0.6-0.8, with values 20-50 times the Knudsen permeability. Ulhom et al. [16], reported a similar behavior for propylene at 263K in y-alumina membranes. Sperry et al. [17] demonstrated the ability of mesoporous y-alumina membranes in methanol separation at 473 K, provided the applied pressure... 

Keywords. Template, Metal oxide, Silica, Porous structures. Sol-gel, Nanoparticles... 

If solvent extraction may be considered a source technique, derived liquid-liquid separation techniques include configurations in which an extraction solvent is physically immobilized by a coating or impregnation process onto a solid support such as silica, porous resin beads, or foam [13,84—87]. Other derived techniques include membranes of various configurations bulk liquid membranes, supported liquid membranes, emulsion membranes, and polymer-impregnated membranes [88]. Many derived liquid-liquid techniques have been developed, especially for use in analytical applications [13,60,62,64,75,84,85,87]. In each of these derived techniques, the... 

L of air is passed over 400 and 200 mg of coconut charcoal in separate tubes at a flow rate of 10-500 mL/min. The analyte is desorbed with methylene chloride and injected into a GC equipped with an FID. A fused-silica porous-layer open tubular column coated with AI2O3/KCI with or without a back-flushable precolumn may be used as a GC column. Alternatively, a 10% FFAP on a 80/100-mesh Chromosorb W column may be used. 

Preparation of Silica Solid Microspheres by Hydrolysis of Tetraethyl Ortho Silicate (TEOS) and Silica Porous Microspheres by Spray Drying Aggregated Colloidal Silica... 

Silica porous microspheres can be prepared by hydrolysis of tetraethyl ortho silicate (TEOS) see Figure 19.1. The reproducibility of the method is demonstrated in Figure 19.2. The product of a scale batch is shown in Figure 19.3. The effect of impurities in TEOS, in Figure 19.4. 

Finally, Figure 19.9 shows the silica porous microspheres product obtained in a 100 gallon kettle scale up process. 

FIGURE 19.10 Silica porous microspheres spray dried 5 W/O aqueous slurry of Cab-O-Sil EH—5 rotary atomizer 45M RPM. 

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