Catalyst, general diffraction patterns

Hall, Dieter, Hofer, and Anderson (19) studied reactions of nitrides and carbonitrides in a reduced, fused iron catalyst (Bureau of Mines number D3001). The results of these experiments were in general similar to those of Jack, and most of the differences may be explained by the differences in the type of iron employed. The major discrepancy was that in the catalyst of large surface area and small crystallite size, the <-carbonitride phase was found under conditions under which massive iron is converted to the f-phase. Since the transformation of the - to the f-phase involves only slight changes in the lattice positions of iron atoms and small changes in the x-ray pattern, it is possible either that this transformation did not occur in the catalyst or that the pattern of the f-phase could not be distinguished from that of the e-phase in the diffuse diffraction patterns. 

X-ray crystallinity. This characteristic is generally indicative of the zeolite content of the catalyst. It is determined by measuring the area of one or several peaks in the X-ray diffraction pattern of the catalyst and expressing it as a percentage of the corresponding area of a reference material (usually a well-crystallized Na Y Zeolite). X-ray crystallinity measurements are often used by refiners to monitor the quantity of fresh and equilibrium catalysts. 

Figure 10.1. X-ray diffraction patterns of fresh and used catalysts (a) fresh catalysts (b) Rh/Al203 (c) Pt/Al203 (d) Pd/Al203. (1) fresh (2) the used catalyst at the catalyst bed inlet (3) the used catalyst at the catalyst bed outlet. Fresh reduced in hydrogen flow at 1123 K. Used reaction conditions of 1123 K, CHVHzO/Oz/Ar = 40/30/20/10, W/F = 0.40 gh mol, 4 h [3]. (Reproduced from Applied Catalysis A - General, 275(1-2), Li BT, Maniyama K, Nunmnabi M, Kunimori K, Tomishige K, Temperature profiles of alumina-supported noble metal catalysts in autothermal reforming of methane, 157-72, 2004, with permission from Elsevier.)...

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