Effect of calcination

Table 5, Effect of calcination temperature of Cera hydrate on the fired properties of p" -alumina...

Figure 5 depicts the effect of calcination temperature on subsequent catalyst activity after reduction at 300°C (572°F). Activity was measured in laboratory tubular reactors operating at 1 atm with an inlet gas composition of 0.40% CO, 25% N2, and 74.6% H2, and an inlet temperature of 300°C. Conversion of CO is measured and catalyst activity is expressed as the activity coefficient k in the first order equation ... 

Harper, F. C. (1967). Effect of calcination temperature on the properties of magnesium oxides for use in magnesium oxychloride cements. Journal of Applied Chemistry, 17, 5-10. 

Boccuzzi F, Chiorino A, Manzoli M, et al. 2001. Au/Ti02 nanosized samples A catalytic, TEM, and FTIR study of the effect of calcination temperature on the CO oxidation. J Catal 202 256-267. 

Larese, C., Lopez Granados, M., Mariscal, R. et al. (2005) The effect of calcination temperature on the oxygen storage and release properties of Ce02 and Ce—Zr—O metal oxides modified by phosphorus incorporation, Appl. Catal. B Environ., 59, 13. 

Effect of Calcination on Activity and Selectivity to Hydrocarbon and C02 of FTS over 15% Co/Si02... 

Hua, Liu, and coworkers—impact of calcination pretreatment on Au/Fe203 catalysts. Hua and coworkers524 525 reported on the effect of calcination temperature on the water-gas shift rates of Au/Fe203 catalysts prepared by co-precipitation of HAuC14 and Fe(N03)3. Calcination temperatures utilized ranged from 200 °C to 600 °C. The impact of calcination temperature on the water-gas shift rate is shown in Table 126. 

The effect of calcination temperature on the Pt dispersion for PTA on silica is clearly seen in Figure 6.23. For both methods of preparation, the dispersion is highest when the catalyst is dried at 100°C and reduced directly thereafter. At this temperature, both catalysts are white in color. As the heating/calcination temperature increases, the color first becomes light brown, and at higher temperature turns dark brown. As the calcination temperature increases, the dispersion decreases approximately linearly. Above about 500°C, the dispersion is nearly identical for both methods of preparation. 

Figure 6.30 Effect of calcination temperature (100°C or 500°C) on dispersion of Pt/y-AI203, reduced at 200°C. (From Liu, J., and Regalbuto, J.R., in preparation.)...

The effects of calcination temperature on the hydrogenolytic behaviors are shown in Fig. 4. The activity increases as the calcination temperature is increased up to 600°C. Then, the conversion is constant until the temperature reaches 750°C, whereupon it drops rapidly. The values of bja indicate almost the same tendency as the conversion. However, the degree of demeth-ylation is almost constant for all calcination temperatures and a(T/TrMeB) = 1.02, j8 = 2.8-4.7%. The increase of conversion by calcination at temperatures... 

Figure 13. Effect of Calcination Temperature 50-50 Mole% MgO-Al203.

Zhang Q, Gao L, Guo J (2000) Effects of calcination on the photocatalytic properties of nanosized TiOj powders prepared by TiCl hydrolysis. Appl Catal, B 26 207-215... 

Figure 11 Effect of calcination temperature of the V-ion-implanted titanium oxide sample on the ESR spectra of + species in the V-ion-implanted titanium oxide photocatalyst at 77 K.

Fig. 45. Effect of calcination on the 31P MAS NMR spectrum at 80.96 MHz of P(CH3)3 adsorbed on zeolite H-Y (202). Samples were degassed at 80°C for 1 hr prior to measurements. Samples calcined at (a) 400°C (b) 500°C (c) 600°C (d) 700°C. The resonance at ca. —3 ppm is assigned to [(CH3)3PH] + complexes formed on the Bronsted acid sites resonances in the region of ca. - 32 to - 58 ppm in samples calcined at 500°C correspond to the phosphine on the Lewis acid sites and the signal at —58 ppm in samples calcined at high temperatures are due to the phosphine on A1203 clusters in the zeolitic cavities. Chemical shifts are in ppm from 85% aqueous H3P04.

Figure 3.5 shows the effect of calcination on the physical properties of HyCOM TiOz s. The crystallite size of anatase and the BET surface area of as-prepared sample were 11 nm and 140 m2g-1, respectively. Upon elevating the calcination temperature, the crystallite size was increased and the surface area was decreased, reflecting crystal growth and sintering of the anatase crystallites upon calcination. It should be noted that even after calcination at 973 K the sample remained in the anatase phase and had a large surface area of 34 m2g-1. The factor of adsorptivity, [Ag+]ads, was also reduced by the calcination (Fig. 3.6) and almost proportional to the BET surface area (Fig. 3.7). This shows that the density (ca-...

Fig. 3.5 Effect of calcination on crystallite size (squares) and BET surface area (circles) of HyCOM Ti02.

Fig. 3.6 Effect of calcination on [Ag+]ads (open circles) and RAg (closed circles).

The effect of calcination temperature on photocatalytic activities of HyCOM Ti02 for mineralization of acetic acid under aerated conditions50 and dehydrogenation of 2-propanol under deaerated conditions9) have also been examined and are shown in Figs. 3.8 and 3.9, respectively. 

Fig. 3.8 Effect of calcination on yield of carbon dioxide from acetic acid solution...

Fig. 3.10 Effect of calcination on the rate of photocatalytic reaction (Ag open circles, acetone closed circles, and 02 squares) in an aqueous Ag2S04 solution (25 mmol dm"3) in the presence of 2-propanol (0.5 mmol).

The most obvious choice to determine phases that may be present in the molybdena catalyst is XRD. Matching of diffraction lines obtained for the catalyst with those of pure bulk compounds gives unequivocal identification of phases present. This is one of the few techniques that yields positive results. The absence of matching diffraction lines, however, is not proof that the phase in question is not present in the catalyst. The XRD technique is limited to particle sizes of above approximately 40 A for oxides or sulfides, lower sized particles giving no discernible pattern over that of the broad alumina pattern. Thus, the presence of a highly dispersed phase, either as small crystallites or as a surface compound of several layers thickness will not be detected. Also, if the phase is highly disordered (amorphous), a sharp pattern will not be obtained, although some broad structure above that of the alumina may be detected. It is a moot point as to whether such a case is considered as a separate phase or a perturbation of the alumina structure. Ratnasamy et al. (11) have examined their CoMo/Al catalyst from the latter point of view, with particular emphasis on the effect of calcination temperature. 

Effects of Calcination. Calcination of RuY or NaCl treated RuY under flowing 02 at 773 K results in the formation of large Ru02 particles which are observable... 

Narayanan, S. and Krishna, K. (1999). Structure activity relationship in Pd/hydrotalcite effect of calcination of hydrotalcite on palladium dispersion and phenol hydrogenation. Catal. Today 49, 57. 

Gehlbach, R. E. Grindstaff, L. J. Whittaker, M. P., "Effect of Calcination Temperature on Real Density of High Sulfur Cokes," presented at 106th AIME Annual Meeting, Atlanta, Georgia, March 6-10, 1977. 

Yu, J.G., J.C. Yu, W.K. Ho and Z.T. Jiang (2002c). Effects of calcination temperature on the photo-catalytic activity and photo-induced super-hydrophilicity of mesoporous Ti02 thin films. New Journal of Chemistry, 26(5), 607-613. 

In an early study of the effect of calcination on the surface area of kaolinite, Gregg and Stephens (1953) found a small but progressive decline in the BET area over the temperature range 100-800°C. These results were in contrast to a 12% loss of structural water at 450°C. It was concluded that there was no detectable activation and that the crystallite structure was not broken up as a result of theimal dehydroxylation. 

Figure 2. Effect of Calcination Temperature With Different Reductions...

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