Catalyst materials based on plasma-processed alumina nanopowder

A platinum catalyst for glycerol oxidation by molecular oxygen has been developed applying the extractive-pyrolytic method and using, as a support, a fine alumina powder with an average particle size of 30-60 nm processed by plasma technology. The extractive-pyrolytic method (EPM) allows affixing small amounts of catalytic metals (1-5%) with the particle size ranging from several nanometers to several tens of nanometers onto the surface of the support. The prepared material - 4.8 wt. % platinum on nano-sized alumina - can be used as a catalyst for glycerol oxidation by oxygen with conversion up to 84%, in order to produce some organic acids (glyceric and lactic acid) with a selectivity of about 60%

Selective liquid phase oxidation of glycerol to glyceric acid over novel supported Pt catalysts

Several supported platinum catalysts were prepared by extractive-pyrolytic method for the selective glyceric acid production from glycerol. Al2O3, Y2O3, Lu2O3, ZrO2-Y2O3 TiO2, SG, Fe2O3, γ-AlO(OH) and C were used as catalyst supports, glycerol oxidation was carried out in the alkaline solutions and oxygen was used as oxidant. The optimal catalyst preparation parameters and glycerol oxidation conditions to obtain glyceric acid were determined. The best result (selectivity to glyceric acid 57% with glycerol conversion 92%) was achieved in the presence of 4.8%Pt/Al2O3 catalyst

Synthesis, Sintering and Characteristics of Hydroxyapatite Nanopowder

The chemical interaction between calcium hydroxide and phosphoric acid was chosen for synthesis of the HAP nanopowder. Various methods for manufacturing dense HAP materials from obtained powders were used and compare

Two-step microwave sintering-A promising technique for the processing of nanostructured bioceramics

Two-step microwave sintering was applied in this study to process dense nano-structured bioceramics coupled with improved mechanical properties. The decrease in the average grain size to the nanolevel resulting from decreasing the sintering temperature to 850 degrees C during two-step microwave sintering, led to an increase in the fracture toughness compared to conventionally two-step sintered bioceramic. The two-step microwave sintering could be a promising technique for the processing of nanostructured HAP bioceramics

Ag+, Cu2+ and Zn2+ doped hydroxyapatite/tricalcium phosphate bioceramics: Influence of doping and sintering technique on mechanical properties

Green hydroxyapatite ceramics were obtained by cold uniaxial and isostatic pressing of hydrothermally synthesized powders, pure hydroxyapatite and hydroxyapatite doped with Ag+, Cu2+ and Zn2+ ions. The ceramics were conventionally and microwave sintered and analyzed by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, X-ray diffraction analysis, and energy-dispersive X-ray spectroscopy. The effect of doping on the mechanical properties of the obtained hydroxyapatite/tricakium phosphate ceramics was examined by comparing their average grain size, porosity and values of the hardness and fracture toughness. The results showed that doping with Cu(2+ )ions caused the lowest porosity of the ceramics and the highest values of hardness and fracture toughness. The ceramics obtained from hydroxyapatite doped with Ag( )(+)and Zn2+ ions exhibited worse mechanical properties due to the higher porosity even in the case of microwave sintering, which provide denser ceramics than conventional sintering