Thermogravimetric analysis surface areas

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. 

The elemental composition of CuCr204 Cu 27.44%, Cr 44.92%, O 27.64%. The catalyst is analysed by measurement of surface area and pore volume also by differential thermal analysis, thermogravimetric analysis and x-ray studies. 

The fresh and spent catalysts were characterized with the physisorption/chemisorption instrument Sorptometer 1900 (Carlo Erba instruments) in order to detect loss of surface area and pore volume. The specific surface area was calculated based on Dubinin-Radushkevich equation. Furthermore thermogravimetric analysis (TGA) of the fresh and used catalysts were performed with a Mettler Toledo TGA/SDTA 851e instrument in synthetic air. The mean particle size and the metal dispersion was measured with a Malvern 2600 particle size analyzer and Autochem 2910 apparatus (by a CO chemisorption technique), respectively. 

ThermoGravimetric Analysis (TGA) was performed on TGAQ50 (TA Instruments) under air up to 800°C. FTIR spectra were obtained on a Spectrum One from Perkin Elmer Instruments. Elemental Analysis was performed by Service Central d Analyse from CNRS located at Vemaison (France). Con-ductimetry back-titration of amine functions (after contact with HCL 0.1 N in excess) was performed using a Tacussel conductimetry probe by a 0.1M NaOH solution. Porosimetry measurements were performed on a SORPTOMATIC 1990 from CE Instruments specific surface areas were calculated using BET model between P/P =0 and P/P =0.4 and pore size repartitions were determined using BJH model. SEM photos were obtained on an Ultra 55 (Zeiss). 

The other posibility for characterizing structural properties of inorganic sorbents deals with the thermogravimetric analysis. By means of this analysis the pore size distribution, pore volume and specific surface area of adsorbents and catalysts which are fundamental adsorption characteristics may be obtained. 

The identity and crystalline purity of the bulk material are determined by PXRD, with the same diffraction pattern as the solvothermal reaction above. Solvent exchange in the pores is confirmed by thermogravimetric analysis and full evacuation is confirmed either by TGA (again, no weight loss until 420°C) or, more rigorously, by gas adsorption (N2,77K, Langmuir surface area of 3909 m2/g). 

Thermogravimetric analysis of the composite catalysts revealed that calcination at 400 °C doesn t provide any degradation of the support materials. XRD patterns reveal that only anatase phase can be identified for the prepared Ti02 and composite catalysts (rutile and brookite phases of Ti02 not being observed). In Table 1 are the surface areas of the catalysts as well as the anatase crystallite dimensions estimated by Scherrer s equation from the (101) reflection plane (20 25 ). 

The optimal calcination method for zeolite beta was established by thermogravimetric analysis using a PL-Thermal Sciences STA 1500 apparatus. Chemical compositions of the zeolites were determined by atomic absorption spectroscopy on a Varian AAIO spectrometer after dissolution of the samples in hydrofluoric acid. The structure was confirmed by x-ray diffraction on a Siemens D-5000 diffractometer and with infrared spectroscopy on a Mattson Instruments Galaxy 2000 spectrometer. Total surface area, micropore area and micropore volume of the samples were determined by argon adsorption on a Micromeritics ASAP 200M volumetric analyzer using standard techniques. Crystal diameters were determined by scanning electron microscopy. 

Synthesized powders were calcined and characterized by standard techniques of thermogravimetric analysis, BET specific surface area measurements, and particle size determination by sedigraphy, as well as X-ray diffraction, and scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) for microchemical analyses. To... 

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