Calcining definition

The carbeniiun ion so formed then reacts in the ICC 1 manner except perhaps for not abstracting a hydride ion from another alkane. Although initial views that zeolites in general were super acids have come into question, definite super acids have been found such as calcined H2S04 Zr(0H)4 which catalyze the isomerization of alkanes at low T. 

To determine the phase properties of the calcined bimetallic nanoparticles, a detailed x-ray diffraction (XRD) study was carried out. The XRD data of AuPt/C showed that the diffraction patterns for the carbon-supported nanoparticles show a series of broad Bragg peaks, a picture typical for materials of limited structural coherence. Nevertheless, the peaks are defined well enough to allow a definitive phase identification and structural characterization. The diffraction patterns of Au/C and Pt/C could be unambiguously indexed into an fcc-type cubic lattice occurring with bulk gold and platinum. We estimated the corresponding lattice parameters by carefully determining... 

But, if atoms were little balls that always united in the same simple ratios to make compound particles , this explained why chemical reactions between elements always took place in constant and simple proportions. It was why, for example, a certain mass of mercury always combined, during calcination, with another fixed mass of oxygen. French chemist Louis Joseph Proust enshrined this principle in his Law of Definite Proportions in 1788. Not that... 

Until it could be proved that the source of the gain in weight of calcined metals was due to combination with a definite and weighable constituent of the air, and that this constituent of the air takes part in all cases of combustion and calcination, the phlogistic philosophy—as elaborated by Stahl, his pupils, and adherents—offered to chemists the first coherent and plausible explanation of all those phenomena which are now known as oxidation and reduction, direct and indirect. 

Lemery defined precipitation as an expression chemists used to describe the fall of a body which had been suspended dissolved in a liquid from which it has been subsequently disunited. Although Fontenelle construed this as a physical definition based on the principles of hydrostatics, Lemery used it to differentiate true metallic precipitates, or the products of displacement reactions, from false ones. One could obtain false precipitates, or the matters that lost their initial metallic form and were reduced to a friable and indissoluble mass, in several ways. Calcination (red and violet mercury), incomplete dissolution in acids (antimony in spirit of salt or in regal water), and calcination after dissolution and evaporation (mercury in spirit of niter), all produced such precipitates. True metallic precipitates differed from false ones in that they were directly separated from their dissolution in liquid. As Lemery put it, false precipitates were abandoned by the liquid, while true precipitates abandoned the liquid themselves. True precipitates were made sometimes naturally through agitation, but mostly with recourse to the intermediates such as alkali salts or other metals. The choice of intermediates depended on the nature of the bodies to be precipitated. Lemery provided an exhaustive discussion for each case. In order to precipitate a resinous matter dissolved in spirit of wine, one could use common water which, by meshing intimately with the spirit, would precipitate the resinous matter. Camphor in spirit of wine could thus be... 

If water was added to the 15% Si02 co-gel to fill the pore voids a partially recrystallized boehmite was formed with a surface area of 464 m /g and with a pore volume of 1.8 oc/g. If water was added to the 15% Si02 co-gel to form a slurry and then dried and calcined at 500 a partially recrystallized bodunite was formed with a surface area of 334 m /g. steam treatment at 760 of this second, small pore, bodunite-like silica-alumina resulted in no change in the surface area. The gas oil cracking activity of the steamed sample was definitely hi er than that for the amorphoias co-gel, i.e., a Micro Activity Test (MAT) Activity Number of 38 (see Table 1.). 

Under certain conditions, there are definite advantages in using hydrochloric, nitric, or other acids to carry out a dissolution step. In their evaluation of proposed processes for the recovery of alumina, Peters ei al. (P8) cited earlier experimental work which showed that both hydrochloric and sulfuric acid are equally good in extracting alumina from calcined clay (TIO). In the separation of the leach liquor from the silica residue by filtration, the chloride solution rapidly separated, while the sulfate solution did not separate easily. In addition to ease of filtration, the hydrochloric acid leach also made the later removal of iron easier. The insolubility of titanium dioxide in hydrochloric acid also eliminated another separation problem. Under this particular situation, hydrochloric acid was the natural choice. As in most large leaching operations, the acid would be recovered and recycled. 

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