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    جغرافية الموضوع: LATITUDE: 22.907250 * LONGITUDE: 58.335820

    وصف الملف: text/tab-separated-values, 1390 data points

    Relation: https://doi.org/10.1594/PANGAEA.942402; Kourim, Fatma; Rospabé, Mathieu; Dygert, Nicholas; Chatterjee, Sayantani; Takazawa, Eiichi; Wang, Kuo-Lung; Godard, Marguerite; Benoit, Mathieu; Giampouras, Manolis; Ishii, Keisuke; Teagle, Damon A H; Cooper, Matthew J; Kelemen, Peter B (2022): Geochemical characterization of the Oman Crust‐Mantle transition zone, OmanDP Holes CM1A and CM2B. Journal of Geophysical Research: Solid Earth, e2021JB022694, https://doi.org/10.1029/2021JB022694; https://doi.pangaea.de/10.1594/PANGAEA.942400; https://doi.org/10.1594/PANGAEA.942400

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    وصف الملف: application/pdf

    Relation: Аналитика и контроль. 2021. Том 25. № 4; Дзюба А. А. Аналитические возможности спектрометра высокого разрешения «Гранд-2000» в дуговом атомно-эмиссионном анализе / А. А. Дзюба, С. В. Додонов, В. А. Лабусов // Аналитика и контроль. — 2021. — Том 25. — № 4. — С. 331-339. — DOI:10.15826/analitika.2021.25.4.009; https://journals.urfu.ru/index.php/analitika/article/view/5551; http://elar.urfu.ru/handle/10995/121248; 85122180605

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    المساهمون: Brognara, A., Beltrami, G., Ardit, M., Gigli, L., Plasier, J., Giordano, G., Migliori, M., Aloise, A., Catizzone, E., Cruciani, G., Martucci, A.

    مصطلحات موضوعية: The zeolite behavior upon heating is of particular importance since catalytic propertie, molecular sieve effects are remarkably enhanced in the dehydrated/calcined state and at relatively high temperatures. The structural modifications occurring in the same zeolite framework are affected by several intrinsic chemical and structural factors (i.e. framework topology, Si/Al ratio, charge-compensating cation, coordination of bare cation, crystal size, heating rate, etc.) [1-3]. The interplay of the factors listed above renders difficult the thermal stability prediction of any given zeolite. Ideally, the effect on the thermal stability of varying the framework Si/Al ratio is best evaluated in a series of isostructural zeolites having different Si/Al ratio. In this work, the step by step thermal dehydration process of four ZSM-5 zeolites with different Si/Al ratio (SAR), has been studied by in situ synchrotron radiation powder diffraction. ZSM-5 samples were prepared starting from the following synthesis gel: TPABr (98%, Fluka), NaOH (97%, Carlo Erba Reagenti), Al(OH)3 (98%, precipitated silica gel (100%, Merck) and distilled water [4]. In order to achieve different Si/Al ratio in the sample, the molar composition of the gel was changed by varying the amount of Al2O3 in the starting mixture: 0.1Na2O−0.08TPABr−xAl2O3−1SiO2–20H2O, with the alumina amount (0.005 < x < 0.033) varied according to the expected Si/Al molar ratio: 15, 50 and 100 [4]. The time-resolved experiment was performed at the MCX beamline at Elettra. ZSM-5 powder samples were placed in a quartz-glass capillary using a gas blower to control the sample temperature. The evolution of the structural features was monitored through 36 structure refinements in the temperature range from 25 to 800 °C by full profile Rietveld analysis. A picture of both kinetics and dynamic behavior of these materials including Temperature-dependent variation of cell parameters and crystal-structure modifications upon heating is presented. High temperature experiments confirm that all ZSM-5 maintain their crystallinity within the investigated T-range. No significant differences in the thermal stability are highlighted. On the contrary, the beta angle variation was found to be affected by the Si/Al ratio. Specifically, the higher the Silicium content the greater the beta angle. Lattice parameters vary continuously on increasing temperature, with a strong change in their evolution close to the temperature at which the monoclinic to orthorhombic phase transition takes place (T100°C). Finally, a negative volume expansion associated with the temperature increase was observed in all investigated ZSM-5 samples. References [1] Alberti, A. & Martucci, A. (2005) In Studies in Surface Science and Catalysi, Elsevier. [2] Alberti

    Time: 25, 155, 19-43, 141, 67

    وصف الملف: ELETTRONICO

    Relation: ispartofbook:AIZ Days 2018; AIZ days 2018; firstpage:40; lastpage:40; numberofpages:1; https://hdl.handle.net/11577/3511603