Calcination metal deposition

Fig. 3.4 Correlation between the initial rate of photocatalytic Ag metal deposition (/JAg) and Ag+ adsorption ([Ag+]ads) of HyCOM Ti02 calcined at 973 K (open circles) and P-25 (closed circles).

Industrial carbon materials are used for molds, structural forms, electrodes of all kinds to be used in current production, metal deposition, and chemicals manufacturing [92]. Their fabrication involves a number of specific operations and processes. For instance, carbon blacks are deposited, collected, and processed. Cokes must be crushed and calcined binders (pitches) must be pulverized and classified. Green mixtures are formed, molded, extruded, baked, and some carbons are also graphitized to provide special properties. 

The most important processes for preparation of magnesium are (a) the electrolysis of fused halide mixtures (e.g., MgCl2 + CaCl2 + NaCI) from which the least electropositive metal, Mg, is deposited, and (b) the reduction of MgO or of calcined dolomite (MgO-CaO). The latter is heated with ferrosilicon CaO-MgO + FeSi = Mg + silicates of Ca and Fe and the magnesium is distilled out. MgO can be heated with coke at 2000° and the metal deposited by rapid quenching of the high-temperature equilibrium which lies well to the right ... 

On the other hand metal films deposited on p"-Al203, a Na+ conductor, are usually found after calcination to contain on their surface large amounts of sodium, which can nevertheless be easily pumped backed into the p"-Al203 lattice via electrical current application.32,33... 

VI. Incomplete calcination of the metal catalyst electrode, resulting to coke deposition on the catalyst-electrode surface. 

TEM-EDS and XPS analyses were conducted on Co/MgO catalysts. The results of surface analyses showed that Co metal is not supported on the MgO as particles, but covers MgO surface in the case of 12 wt.% Co/MgO calcined at 873 K followed by reduction. After the reduction of catalyst at 1173 K, both cobalt oxide and CoO-MgO solid solution are observed on the surface of catalyst. In the steam reforming of naphthalene, two types of coke deposited on the surface of catalyst are observed. These are assigned to film-like and graphite type carbon by TPO analysis. 

Gas-phase grafting (GG) is characteristic in that gold can be deposited even on the acidic surfaces, such as activated carbon and on Si02 [27]. The vapor of gold acac complex is adsorbed on the support powder probably through the interaction of electron-rich oxygen atoms in acetylacetonate and then calcined in air to decompose it into metallic gold particles. 

Over An deposited on 3-D mesoporous Ti-Si02 with pore diameter of 9nm, one of the best results was obtained. At an SV of 4000 h/mL/g-cat., propylene conversion above 8%, PO selectivity of 91% giving a steady STY of 80 g PO/h/kg-cat. [84]. The surfaces of 3-D mesoporous Ti-Si02 were trimethylsilylated for rendering hydro-phobicity, which enables higher temperature operation of reaction [86]. As a solid phase promoter, alkaline or alkaline earth metal chlorides are efficient, however, chloride anions markedly enhance the coagulation of An particles in a short period [87]. Finally, Ba(N03)2 was selected as the best promoter which might kill the steady acid sites as BaO (after calcination) on the catalyst surfaces [84,88]. 

If the positive effect is observed on a specimen deposited in the hydrogen atmosphere, then after the specimen is calcined in vacuo, this being accompanied by an increase of es, it is replaced by the negative effect (transfer from the point A to the point F in Fig. 9). Such an inversion (change of sign) of the photocatalytic effect due to the calcination of the specimen in vacuo (after it is annealed in hydrogen) was observed by Kohn and Taylor (40) who worked with hydrides of various metals. 

Fu et al. 02 reported enhanced OSC with Au addition to ceria based on the CO pulsing technique. They were also unable to discern the active state of Au, as both metallic and ionic species were present in XPS measurements after calcination at 400 °C. In a later report, the authors403 removed metallic Au particles by extraction with a 2%NaCN solution and observed that the lightoff curves remained unchanged, with activation energies being virtually identical for the leached materials relative to the materials prior to leaching, 47.8 kJ/mol for deposition-precipitation method... 

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