XRD measurements

A 5 wt.% CoOx/Ti02 catalyst gave the most promising activity for continuous catalytic wet oxidation of trichloroethylene at 310 K with a unsteady-state behavior up to 1 h. The catalyst after the oxidation possessed a Co 2p3/2 main peak at 779.8 eV, while the peak was obtained at 781.3 eV for a fiosh sample. Only reflections for C03O4 were indicated for these samples upon XRD measurements. The simplest model for nanosized C03O4 particles existing with the fi"esh catalyst could reasonably explain the transient activity behavior. 

Fig. 4 Oxygen Is XPS spectra including curve-fitted components for (a) Catalyst I, (b) Catalyst I after reduction In Fig. 2, a marble-like pattern was observed, which is attributable to solid solution phase of CoO and MgO, because XRD measurement on Catalyst II showed the existence of CoO-MgO solid solution phase [7, 8]. On the other hand, for Catalyst I, no solid solution phase of CoO-MgO was observed. In addition, XRD pattern of Catalyst I indicated the existence of CoO or C03O4. These results suggest that in the case of Catalyst I, Co is loaded on the surface of MgO as CoO or C03O4 phase. Magnified TEM image of Catalyst I after reduction is shown in Fig. 3. In this figure, crystalline lattice image was observed. It is likely that the observed lattice corresponds to the metal phase of Co, because XRD measurement on Catalyst I after reduction showed the existence of Co metal phase [7, 8].

X-ray diffraction (XRD) measurements were carried out using a Dlano XRD-6 powderdiffractometer with CuKa radiation. 

The results of the XRD measurement showed that the Fe jAl, jPO catalyst was almost in amorphous state. Only a very broad peak at 29 of ca. 23 degree was observed. The Mossbauer spectroscopic study on this catalyst showed one doublet of iron with the isomeric shift of 0.31 mm s (a-Fe was used as the reference) and the quadrupole splitting of 0.62 mm s. These parameters are very close to those observed for FePO [13, 14], suggesting that the iron cation in the catalyst is tetrahedrally coordinated with oxygen and isolated by four PO tetrahedral units. Such coordination circumstance was suggested to be a key factor for the iron site effective for the oxidation of CH to CHjOH by H -Oj gas mixture [15]. 

In this zeolitic material a very low percentage of Ti(IV), dispersed in a pure siliceous microporous matrix (with the MFI framework, the same as that of the ZSM-5 zeolite), is able to oxidize in mild conditions many substrate with extremely high activity and selectivity (see Sect. 2). However, after more than three decades, a complete picture of reaction mechanisms is still missing. Major problems related to characterization are due to the extremely high dilution of Ti(IV) in the zeolitic matrix and the presence of high amounts of water in the reaction media. The first point requires characterization techniques very sensitive and selective towards Ti(IV). For instance, XRD measurements have been able to recognize the presence of Ti(IV) in the framework only indirectly, via the measured unit cell volume increase [21,22], but attempts to... 

Although the dopant dissolves in the ceria lattice, we cannot rule out the presence of an amorphous dopant-rich phase at the surface of the catalyst (even after severe calcining). XPS + XRD measurements show a dopant-lean bulk and a dopant-rich surface. The structural similarity of the different catalysts is supported by the surface area-pore volume relationship (Figure 3). 

Powder X-ray diffraction patterns were measured on PANalytical X Pert PRO high-resolution diffractometer with Alphal configuration using CuKa radiation (1.5406 A) in the range from 5° to 35° 20 with the 0.017° step per 100 s using fully opened X Celeration detector. For the XRD measurements Ti-Beta precursor gels were dried at ambient temperature and than grinded to powder. 

Crystallinity of the final zeolites was high as determined by XRD measurements (diffraction patterns not shown) and was confirmed by their high micropore volumes, which are compared in table 1 together with other physico-chemical properties. A commercial beta zeolite (CP811, Zeolyts Int.) is included for comparison purposes. 

Several workers have reported that bulk carbide does not form readily during normal FTS conditions.76 82 Bureau of Mines work, using laboratory XRD measurements, showed that detectable amounts of bulk carbide were not formed under synthesis conditions.82... 

Figure 6.6 In situ XRD of an alumina-supported iron catalyst during reduction in H2 at 675 K reveals the transition of a-Fe202 (hematite) via Fe(04 (magnetite) to metallic iron as a function of time. The graph shows the degree of reduction of supported and unsupported oc-Fe203 as determined from the XRD measurements (from Jung and Thomson f 14]).

Figure 6.20 Quick EXAFS and XRD measurements recorded during the temperature programmed reduction of copper in a Cu/Zn0/Al203 methanol synthesis catalyst. The disappearance and appearance of peaks with increasing temperature in the series of EXAFS spectra corresponds to the conversion of oxidic to metallic copper. The intensity of the relatively sharp peak around 9040 eV, indicative of Cu metal, clearly illustrates the kinetics of the reduction process, as does the intensity of the (111) reflection of Cu metal in the XRD spectra (adapted from Clausen 44J).

XRD Characterization The powder x-ray diffraction of the mechano-chemically milled complex borohydride has been carried out by the Philips X pert diffractometer with Cu-Koi radiation of X= 5.4060 A. The incident and diffraction slit width used for the measurements are 1° and 2° respectively. The sample holder was covered with Polyethylene tape (foil) with an O-ring seal in an N2 filled glove box in order to avoid or at least minimize the 02/moisture pickup during the XRD measurements. The diffraction from the tape was calibrated without the actual sample and found to be occurring at 29 angles of 22° and 24°, respectively. The XRD phase identification and particle size calculation has been carried out using PANalytical X pert Highscore software, version l.Of. 

Characterization. IR spectra of the samples were recorded on Nicolit AVATAR360 spectrometer. The TEM images were obtained on Hitachi H-8100IV electron microscope. TGA and DTA analyses were carried out in Du pont 9900 Thermal Analysis System. X-ray diffraction (XRD) measurement was conducted on a Siemens D5005 diffractometer using Cu Ka radiation (X = 1.54 °A). 

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