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Mechanochemical Preparation of Alumina-Ceria
Jirátová, Květa ; Spojakina, A. ; Tyuliev, G. ; Balabánová, Jana ; Kaluža, Luděk ; Palcheva, R.
Ceria containing catalysts play an essential role in heterogeneous catalytic processes. However, ceria shows poor thermal stability and low specific surface area and therefore, many studies have been done to improve its properties by combination with other oxides. Alumina-ceria is substantial component of the three ways catalysts, due to the ceria ability to function as the buffer of oxygen and to enhance the oxygen storage capacity of the catalysts. Ceria in these catalysts also functions as structural promoting component, increasing alumina stability towards thermal sintering. Promising method of oxides preparation, very interesting and simple but not sufficiently studied yet is a mechanochemical synthesis. Here we report on the synthesis of nano-sized alumina, ceria and ceria-alumina of various compositions by a wet solid phase mechanochemical reaction of hydrous aluminum, and/or cerium nitrate with ammonium bicarbonate after addition of a small amount of water. The aim of this contribution is to study processes being in progress during synthesis of the mixed oxides, interaction between components and their mutual effect on the properties of resulting products. The phase evolution during mechanical milling and the subsequent heat treatment of precursors were studied by X-ray diffraction, DTA/TG, H2-TPR, NH3-TPD, CO2-TPD, N2 adsorption at -195°C, IR, and XPS spectroscopy. Alumina and mixtures of alumina with different quantities of CeO2 (1- 18 wt. %) were synthesized by mechanochemical method from aluminum nitrate, cerium nitrate and ammonia bicarbonate.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22015083108560 - PDF
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12M-IMMEDIATE Research Report: Preparation of Pt on Carbon Black Supported Catalysts
Kaluža, Luděk ; Zdražil, Miroslav ; Gulková, Daniela ; Vít, Zdeněk ; Šolcová, Olga ; Soukup, Karel ; Maixnerová, Lucie
The aim of this work was to elucidate on advanced preparation of Pt/C catalysts from TimCal carbon black and H2PtCl6. The attention was directed to residual content of chloride in the prepared catalysts and scale-up to the amount about 1 gram of final product. The textrual properties of the supports and selected catalyst were studied by nitrogen physisorption. The analytical methods such as instrumental neutron activation analysis (INAA), liquid ion chromatography (LC), and titration with silver nitrates were applied for Cl analysis. Electron probe micro analysis (SEM-EDX), hydrogen chemisorption, temperature programed desorption of hydrogen (TPD) and a simplified determination of ignition temperature in air flow were used for Pt/C catalysts characterization.
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