Silica Cab-O-Sil

We have recently tested the Tx model described above by obtaining T, measurements in powder samples with known S/V. Samples used were constructed from fumed silica (CAB-O-SIL M-5 and TS-500, Cabot Corp.), and were either hydrophilic (M-5) or treated by the manufacturer to be hydrophobic (TS-500). Powder of each type was pressed into a polycarbonate cylinder, with a degree of compression controlling the pore space volume of each sample. These materials have a very high specific surface area (200 m2 g 1 for M-5, 212 m2 g-1 for TS-500), which is not expected to change significantly even at the maximum compaction pressure used. 

T60/T64, Cabot Corp.) Fumed silica (Cab-O-Sil, Cabot Corp.) Bentone 27 (Rheox, Inc.) 10 5 10 5... 

Kinetics of several organosilicon compound chemisorption from the gas phase on the non-porous silica (Cab-O-Sil M5) surface is described by the well-known Elovich equation [27] ... 

The addition of 6% pyrogenic silica (Cab-O-Sil) to the above mixtures changed the picture only slightly. 

A 500 ppm dispersion of silica (Cab-O-Sil, EH-5, Calbot Corp.), 8 liters in volume, was prepared by dilution of a 2 g/1 dispersion idiich had been sonicated for 40 min. in a Bransonic ultrasonic bath. The turbidity of the final solution was 24 NTU. With the permeate valve closed, the cross-flow velocity and formation pressure were set. Timing for a total of 30 min. was begun idien the permeate was opened, and readings of permeate flow rate and turbidity were taken at periodic intervals. After formation, and without allowing system shut-down, the silica solution was flushed out with DI water and replaced with the Pazomus B oil emulsion. (Emulsion concentrations are % vol/vol, e.g., 3% represents 30 cc/1 of the commercial mixture.)... 

All silica MCM-41 was synthesised by making a homogeneous mixture of Cab-0-Sil (3.96 g, 66 mmol) and tetramethylammonium hydroxide solution 25 wt% Aldrich (12 g, 33 mmol). This was added to a mechanically stirred mixture of sodium silicate Aldrich (18.84 g, 154 mmol), silica Cab-O-Sil (13.8 g, 230 mmol) and water (84 g,... 

A 1.5 % w/w Ni supported on silica (Cab-O-Sil 5M, 194 m g ) catalyst precursor was prepared by homogeneous precipitation/deposition as described in detail elsewhere (24). The hydrated sample, sieved in the 150-200 pm range, was reduced, by heating directly in a 100 cm min stream of dry H2 (99.9%) at 5 K min to 673 1 K which was maintained for 18 h. Under these activation conditions the catalyst supports 1.1 x 10 exposed Ni atoms/g catalyst with a surface weighted average Ni diameter = 1.4 nm these values are based on chemisorption measurements (12). 

Figure 1. Partial reaction composition diagram. Projection of the NazO, Al2Os, Si02> P205, H20 system at 100°-125°C. Na90 4-Si02 + P2Os = 100 mole %. Al2Os = 12-20 mole % of the total anhydrous gel composition mole H20/Al203 is constant (= 110). A solid colloidal silica ( Cab-O-Sil ) is the silica source.

Flow agents such as magnesium carbonate and fumed silica [Cab-o sil and Sant-o-sil ] are sometimes added to flash powders to facilitate mixing and automated loading. 

Two C0/S1O2 catalysts, one supported on silica gel (Grace Davison Grade 654) and the other supported on fumed silica (Cab-O-sil M-5) were prepared by a non-aqueous (acetone) evaporative deposition. The cobalt metal loading was 11 wt. % for both catalysts. Details of the preparation method are discussed elsewhere [22, 23]. 

Structural Parameters of Unmodified and Modified Fumed Silica Cab-O-Sil... 

Fillers for epoxy adhesives used in weldbonding include silica (Cab-O-Sil, 7% by wt) to prevent run-off, 3% strontium chromate to provide corrosion inhibition, and conductive metal powders. Viscosity of adhesives in paste form has an important effect on the weld and bonded joint. Viscosity must be low enough to allow the force of the electrodes to push the adhesive out of the interface contact area, yet sufficiently high or thixotropic so that it will not flow out of the joint during the cure cycle. 

The Cr, Ti catalysts were prepared by impregnation with Cr(N0j)3.9H20 (Allied Chemical Co.) onto silica (Cab-O-Sil) followed by impregnation with Ti(iP) (iP = isopropyl, Aldrich) (preparation method 1) or in the reverse order onto the same support (preparation method 2). Ti impregnation was done in a toluene solution under nitrogen to avoid decomposition of the air-sensitive precursor The Cr- and Ti-contents were respectively 0.5 and 1.5 wt%. 

A mixture of OF2 on silica gel (60/80 mesh) and liquid OF2 at 254 Torr in 3-or4-mm internal diameter tubes exploded spontaneously when the temperature exceeded 77 K. With a 5-mm tube there was no explosion [1,2], see [3] for an explanation. Mixtures of liquid OF2 with pyrogenic silica (Cab-O-Sil) in 10- to 12-mm tubes are shock sensitive but are chemically stable at -78°C. Explosions of silica gel and liqu id OF2 mixtures might be due to traces of water [4, 5]. 

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