Silica metal impregnation

High-density polyethylene (HDPE) is produced by a low-pressure process in a fluid-bed reactor. Catalysts used for HDPE are either of the Zieglar-type (a complex of A1(C2H5)3 and a-TiCl4) or silica-alumina impregnated with a metal oxide such as chromium oxide or molybdenum oxide. 

Figure 3. Schematic representation of the selective synthesis of metal nanowires and nanoparticles by the Sintering Controlled Synthesis approach, (a) Mesoporous silica, (b) impregnation of mesoporous silica with metal ions, (c) addition of water/alcohol vapors and UV-irradiation, or wet H2-reduction, (d) formation of metal nanowires, (e) dry H2-reduction, (f) formation of metal nanoparticles.

Glycerol hydrogenolysis has also been illustrated over transition metals impregnated on silica. Some metals, such as Co and Pt, appear inactive for glycerol conversion, while others, such as Rh, Pd, Ir and, especially, Ru are active but lack the... 

Figure 5. Small-pore silica-alumina catalyst after metal impregnation...

Sfiica impregnated with saturated and unsaturated hydrocarbons (squalene, paraffin oil), silicone and plant oils, complexing agents (silver ions, boric add and borates, unsaturated and aromatic compounds), tigands (EDTA, digitonin), and transition metal salts silanized silica gel impregnated with anionic and cationic surfactants Cross-linked, polymeric dextran gels (Sephadex)... 

The effect of the presence of crown ethers in the eluents [7,33], or in the stationary phases [34-37] on the effectiveness of separation of alkali metals on cation exchangers has been investigated. Higher selectivity of Na separation was observed on silica resins impregnated with calixarene [38]. 

The presence of sodium on a catalyst also influences its behavior during ethylene polymerization [541,606-608]. When sodium is present, Cr/silica produces its peak activity, and highest MI polymer, after activation at lower temperatures. Other alkali metals can have a similar influence. Figure 141 shows the results of polymerization tests conducted with Cr/silica-titania impregnated with varying levels of sodium formate or lithium formate, followed by activation at 650 °C. The activity of the catalyst and the MI of the polymer it produced pass through a maxima at a loading of about 0.3 Na or Li ions nm-2. 

LCB is also enhanced by the addition of alkali metal, as might be expected from its acceleration of annealing. In one test of LCB trends, a silica was impregnated with sodium ions, which caused a reduction in the surface area of 30-50% when it was heated to only 600 °C. This silica was then washed repeatedly with liquid water numerous times to remove the sodium then chromium was applied. After a second activation at only 600 °C, this catalyst produced polymer with high levels of LCB. The fusion of the silica primary particles caused a large increase in LCB. This happened although the chromium, and in this case even the silica, had never experienced a high activation temperature. 

Coke/Steam Reaction Rates on Metal-Impregnated Durabead (Silica-Alumina) TCC Catalysts at 1500°F... 

Application of New Metal Impregnated Knitted Silica-Fiber on Catalytic Oxidation and Hydrogenation Processes... 

Back in 1978, Kaimai and Matsunaga tried to separate PAHs and PASHs by thin layer chromatography on silica gel impregnated with several metal acetates. Mercury acetate showed the best results. Following that idea, separation was tested by Andersson on a mercury-acetate-substituted phenyl kieselguhr. However, PASHs could not be separated selectively. 

Sarin and other nerve agents may be removed from cleaning organic solvents (trichlorotrifiuoroethane and its mixtures) by such adsorbents as Fuller s earth, activated alumina, silica gel, and silica gel impregnated with a metal salt (Fowler and Mcll-vaine 1989). Hydrolysis with water or dilute alkalies should yield products of low toxicity. 

Noble-Metal Impregnation Example onto a Modified Silica-Alumina Support... 

Separation, preconcentration, and purification of metal ions from dilute aqueous solutions were accomplished by silica gel impregnated with a mixture of Calcon and Aliquat 336 as chelating sorbents. The relative capacities of 33 metal ions were determined in different experimental conditions of pH range as well as the concentrations of hydrochloric acid and perchloric acid. ... 

Sorption of metal ions such as Ca, Mg, Al, Cu, Fe, Ni, Co, Cd, Zn, Pb, Hg, and Cr on silica gel impregnated with a mixture of Aliquat 336 and Titan Yellow was investigated in the pH range 1-9. The column extraction chromatography application of the sorbent to the separation of solutions of analytical reagent grade sodium, potassium, calcium, magnesium, and ammonium chloride from traces of Cu, Pb, Cd, and Zn, and the separation of some metal ion mixtures were also reported. " ... 

Stationary phase S = silica gel G impregnated with 3% Primene JM-T So = silica gel impregnated with 5% Primene JM-T Sj = silica gel impregnated with 0.15% Primene JM-T. Mobile phase M, = 0.05 M citric acid M2 = 0.1 M citric acid, M, = 1.0 M citric acid. Conditions Ascending technique, layer thickness 0.5 mm, loading volume 5 /ul of 2.5% metal ion solution. Remarks Investigation of effects of eluent and impregnant concentrations on the Rf values of metal ions. An inverse correlation between Ry-values and the %E (E = extraction) of the metal ions is observed. S1-M2 is identified as the best system. 

Silica gel impregnated with a metal salt or phenol... 

Pesticides Organophos-phorus compounds Silica gel G C6Hi4-xylene- EtOAc- MeaCO (50 15 5 18) Exposure to I2 Adsorption 153 Silica gel impregnated with a metal salt or phenol... 

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