EVALUATION BY XRD

XRD. The crystallinity of the mineral phase of the composites was evaluated by XRD with a Siemens D500 instrument using Cu Ka radiation. 

Table 10.3 Lattice constant (a) and strain parameter (b) evaluated by XRD.

Solids were characterized by XRD, N2.BET surface area, and FT-IR. The antacid capacity of the synthesized zeolites was evaluated using the methodology reported by Rivera et al. [7] and Linares et al. [6]. The pepsin enzymatic activity was determined by the reaction between a specific mass of the solid and a denatured haemoglobin solution [8]. 

Nitrogen adsorption was performed at -196 °C in a Micromeritics ASAP 2010 volumetric instrument. The samples were outgassed at 80 °C prior to the adsorption measurement until a 3.10 3 Torr static vacuum was reached. The surface area was calculated by the Brunauer-Emmett-Teller (BET) method. Micropore volume and external surface area were evaluated by the alpha-S method using a standard isotherm measured on Aerosil 200 fumed silica [8]. Powder X-ray diffraction (XRD) patterns of samples dried at 80 °C were collected at room temperature on a Broker AXS D-8 diffractometer with Cu Ka radiation. Thermogravimetric analysis was carried out in air flow with heating rate 10 °C min"1 up to 900 °C in a Netzsch TG 209 C thermal balance. SEM micrographs were recorded on a Hitachi S4500 microscope. 

Preparation and characterization of two-dimensional zirconium phosphonate derivatives in either crystalline or amorphous forms have been investigated. Two composite zirconium phosphonates in single crystal phase have also been investigated and characterized by XRD, i c-, and 3ip-MASNMR. The catalytic performance over zirconium phosphonates are evaluated by hydrolysis of ethylacetate in aqueous solution. When the composite zirconium phosphonate is composed with an acidic function and with a hydrophobic function in single crystal phase, the catalytic activity in aqueous medium showed higher activity than that of single acidic zirconium phosphonate. The composite materials become accessible to any reactant molecule and improve hydnq>hobicity. 

With the aim to study the characteristics of VPO catalysts in the course of butane oxidation to maleic anhydride together with a simultaneous evaluation of the catalytic performance, we have used Raman spectroscopy which is a very sensitive probe for determining the presence of V0P04-like entities together with (VO)2P207. An in situ Laser Raman Spectroscopy (LRS) cell was built in our laboratory (6). In the corresponding publication (6 ), the preparation and the characterization by XRD, Ip... 

The stability of MCM-41 is of great interest because, from the practical point of view, it is important to evaluate its potential application as a catalyst or adsorbent. It is known that purely-siliceous MCM-41 (designated here as PSM) has a high thermal stability in air and in oxygen containing low concentration (2.3 kPa) of water vapor at 700 °C for 2 h [1], However, the uniform mesoporous structure of PSM was found to be collapsed in hot water and aqueous solution due to silicate hydrolysis [2], limiting its applications associated with aqueous solutions. After MCM-41 samples were steamed in 100% water vapor at 750°C for 5 h. their surface areas were found to be lower than amorphous silica-alumina and no mesoporous structure could be identified by XRD measurement [3]. In addition, PSM showed poor stability in basic solution [4]. 

On the first stage of hydrogenation reaction the C/H composition of fulleranes can be approximately determined by XRD from increase of unit cell parameter. The crystal structure of fulleranes powder remains to be fee like in pristine C60 but the cell parameter increases proportionally to the number of attached hydrogen atoms due to increase of van der Waals diameter of molecules. Using chemical analysis on carbon/hydrogen ratio performed on samples hydrogenated at various conditions we constructed the dependence which could be used for approximate evaluation of hydrogen content from known cell parameter determined from powder XRD, see Fig. 5.3... 

PtRu catalysts with controlled atomic ratios were prepared by adjusting the nominal concentrations of platinum and ruthenium salts in the solution, whereas different mean particle sizes could be obtained by adjusting some electric parameters of the deposition process, e.g., ton (during which the current pulse is applied) and toff (when no current is applied to the electrode), as determined by different physicochemical methods (XRD, EDX, and TEM) [40], Characterization by XRD led to determine the crystallite size, the atomic composition and the alloy character of the PtRu catalysts. The atomic composition was confirmed using EDX, and TEM pictures led to evaluate the particle size and to show that PtRu particles formed small aggregates of several tens of nanometers (Figure 9.10). 

The identification of the solid phases and the determination of their crystallinities were carried out by X-ray powder diffraction (XRD), using a Philips PW 1349/30 X-ray diffractometer (Cu-KOt radiation). The crystallinity of each sample was evaluated by using as standard the most crystalline as-synthesized ZSM-48 from which the residual amorphous phase was further removed by ultrasonic treatment (15.). Alkali and A1 contents... 

Figure 6. Dependencies between the pore widths at the maxima of suitable PSDs obtained from nitrogen adsorption data and the pore width evaluated from the XRD spacing via equation (1). All closed points correspond to the maxima of PSDs obtained by the HK method with the SF (equation 3), KJS (equation 4) and ZLZ (ref [29]) A(w) curves. The open circles correspond to PSDs evaluated by the KJS method, which incorporates the MCM-41 calibrated t(A) and A(w)-relations into the BJH algorithm [26],...

Catalytic nickelsilicate membranes were synthesized by in-situ techniques on pretreated a- and 7- alumina supports. The resulting films and bulk materials have been characterized by XRD, Nz adsorption-desorption, SEM, TEM and FTIR spectroscopy. Their permeation performances of gases and liquids and catalytic activity in the selective oxidation of styrene with HzOz have been evaluated. The formation, morphology, permeation and catalytic properties of the membranes have been correlated with nature of alumina supports, their surface pretreatment and conditions of the hydrothermal synthesis. The results show a strong effect of 7-alumina surface on the morphology and properties of the membranes. 

The cross section of the films were observed and their porosity were calculated by the point counting method. Cracking of the films were also observed by optical microscope. The phase structure of the film was analyzed by XRD analysis using Cu-Ka radiation. Chemical dispersion of a cross section was evaluated by EPMA. An area of a cross section of the thick film was also calculated with a outline including porosity. Adhesive strength was qualitatively analyzed whether the film can be peeled with a knife or not. 

The effect of antimony precipitation on FeSb04 (method B) was evaluated using the ammoxidation of propene and propane. The exact amount of antimony which was precipitated on the surface could not be determined. The catalyst used in the catalytic study showed by XRD only the presence of FeSb04 not of a-Sb204. 

The carbonate content of mudrocks was determined by weight loss upon reaction with 10% HCl (Table 3). The mineralogy of the mudrocks was determined by XRD (X-ray dilfraction) of randomly oriented whole-rock powders mineral percentages were calculated using the method of Lynch (in review). Further evaluation of the clay minerals... 

The fresh and used catalysts were characterised by BET-SA, XRD, ESR, coke content and TPD of ammonia and evaluated by the dismutation activity of CCI2F2 at various temperatures ranging from 275-450°C. An all glass high vacuum unit (lO" torr) was used for the measurement of BET surface area. The XRD patterns were recorded on the Phillips PW 1051 diffractometer using Ni-filtered Cu-Ka radiation. ESR spectra were recorded at room temperature on a Bruker ER 200D-SRC X-band spectrometer with 100 kHz modulation. The carbon content of the catalysts were determined on a Perkin-Elmer 240-B microanalyser. 

The applicability of the Pt deposition precipitation technique (DP) on mesoporous silica has been evaluated and discussed. A detailed synthesis procedure is given, and a suitable support from the SBA-15 family has been identified. The material synthesized at the conditions described here was clearly able to withstand the severe conditions of the DP treatment, indicating improved hydrothermal stability. The incorporation of the active species was accomplished without compromising the structural integrity of the parent material, as monitored by XRD and N2-sorption measurements. Using UV-Vis diffuse reflectance spectroscopy we were able to detect the platinum surface complex that coexists with platinum nanoparticles on the impregnated solid. 

Pt was well consistent with that evaluated by Scherrer equations for their XRD patterns. These results implied that the coverage of Pt metal particles with silica layers would not prevent the contact of gaseous molecules. 

Metallic silver is clearly evidenced by XRD beside mullite and corundum phases. The crystallite sizes are reported in Table 2 as well as the specific surface area. After the evaluation tests, we can observe a strong decrease of the intensity of the silver diffraction peaks disclosing a loss of the active phase during the hydrogen peroxide flow. In the case of sample Bl, an important weight loss is observed (- 8.1 %, Table 1), whereas for sample C, the weight loss is much lower (- 0.9 %) and a part of metallic silver transforms into silver oxide. 

XRD and TEM analyses provided the bulk information on the M-CZ and CZ catalysts. However, as another information, the surface distribution of Zr and Ce species is very important for the evaluation of OSC because the reduction-oxidation mainly occurs on the surface not in the bulk. Surface Zr/Ce ratios by XPS spectra were calculated to be 0.49 for the CZ catalyst and 0.84 for the M-CZ catalyst, respectively. Probably, the Ce rich surface on the CZ catalyst is formed during the diffusion process in the solid-solid reaction when the as-prepared was reduced at 1473 K and the surface Ce species might be present as CeOa form observed by XRD(Fig. 1). Consequently, it is found that the segregation on the surface is preventable by the presence of MgO. 

To evaluate the effective relative amount of different metals and their interdispersion SEM microanalyses have been performed. The samples calcined at temperatures higher than 973 K showed a molybdenum amount lower than the theoretical one, probably because at the hipest temperature Mo oxide volatilizes from the lattice. The theoretical amount of different metals was respected for all the other samples. The effective pr ence of metal oxides, yet not detectable by XRD and Raman spectroscopy, was detected by SEM microanalysis in all samples. 

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