Effect of the metal-support interaction in Ag/CeO2 catalysts on their activity in ethanol oxidation

The interaction of silver with the surface of CeO2 in the Ag/CeO2 catalysts prepared by coprecipitation and impregnation techniques was studied by temperature-programmed reduction, X-ray diffraction, and high-resolution transmission electron microscopy. It was shown that coprecipitation technique led to formation of strong silver–support interaction and the epitaxy of silver particles (d111 = 2.35 Å) on the surface of CeO2 (d111 = 3.1 Å). This provided incresed catalytic activity in the oxidative dehydrogenation of ethanol at relatively low temperatures (a 15% conversion of ethanol with 100% selectivity for the formation of acetaldehyde was reached at 85°C). Above 130°C, the deep oxidation of ethanol to CO2 becomes the predominant direction of a catalytic reaction, and the Ag/CеО2 catalyst obtained by impregnation technique was most active in this region as a consequence of the weaker metal–support interaction

Effect of the metal-support interaction in Ag/CeO2 catalysts on their activity in ethanol oxidation

The interaction of silver with the surface of CeO2 in the Ag/CeO2 catalysts prepared by coprecipitation and impregnation techniques was studied by temperature-programmed reduction, X-ray diffraction, and high-resolution transmission electron microscopy. It was shown that coprecipitation technique led to formation of strong silver–support interaction and the epitaxy of silver particles (d111 = 2.35 Å) on the surface of CeO2 (d111 = 3.1 Å). This provided incresed catalytic activity in the oxidative dehydrogenation of ethanol at relatively low temperatures (a 15% conversion of ethanol with 100% selectivity for the formation of acetaldehyde was reached at 85°C). Above 130°C, the deep oxidation of ethanol to CO2 becomes the predominant direction of a catalytic reaction, and the Ag/CеО2 catalyst obtained by impregnation technique was most active in this region as a consequence of the weaker metal–support interaction

The system of early warning on strong sub-crustal earthquakes of the Vrancea zone

The article is devoted to the issue of seismological monitoring and automatic warning of the personnel of potentially hazardous manufactures on the approaching of seismic threat and warning the population, in order to advance their preparation and minimize negative consequences. International experience of creating a system of early warning of earthquakes has been analyzed. The main factors, which determine the seismicity of the territory of Ukraine, have been considered. A model of the system of early earthquake warning for the objects of critical infrastructure of Ukraine has been proposed

Ag/CeO2 Composites for Catalytic Abatement of CO, Soot and VOCs

Nowadays catalytic technologies are widely used to purify indoor and outdoor air from harmful compounds. Recently, Ag–CeO2 composites have found various applications in catalysis due to distinctive physical-chemical properties and relatively low costs as compared to those based on other noble metals. Currently, metal–support interaction is considered the key factor that determines high catalytic performance of silver–ceria composites. Despite thorough investigations, several questions remain debating. Among such issues, there are (1) morphology and size effects of both Ag and CeO2 particles, including their defective structure, (2) chemical and charge state of silver, (3) charge transfer between silver and ceria, (4) role of oxygen vacancies, (5) reducibility of support and the catalyst on the basis thereof. In this review, we consider recent advances and trends on the role of silver–ceria interactions in catalytic performance of Ag/CeO2 composites in low-temperature CO oxidation, soot oxidation, and volatile organic compounds (VOCs) abatement. Promising photo- and electrocatalytic applications of Ag/CeO2 composites are also discussed

Two-stage electro-discharge machining fabricating superhard cutting tools

Abstract A novel technique for fabricating efficiently precision cutting tools made from polycrystalline superhard materials is reported in the present paper. For this purpose, a two-stage electro-discharge machining (EDM) was applied on diamond polycrystallines, by employing first wire-electrode EDM for rough cutting and subsequently rotational disc-electrode EDM for finishing operations. Experimental results obtained clearly indicate the applicability of the proposed two-stage technique for fabricating precision cutting tools that can be used for the production of machined components made from glass and plastics, ceramics, composite materials and non-ferrous metals, at an industrial scale