State of the Active Component and Catalytic Properties of Pd/C Cata- lysts on the Selective Hydrogenation of Butadiene-1,3 into Butylenes

Palladium (0.25-5.8 wt.%) was supported on three different types of filamentous carbon in which the basal graphite planes are arranged along, crosswise and at a 45° angle to the axis of a nanofiber. HREM, XPS and X-ray techniques were used to study the state of high dispersed Pd particles supported on the filamentous carbon. It was established that the type of the carbon support affects the properties of the active component. The high disperse Pd particles most strongly interact with the prismatic planes of graphite to provide electron transfer from palladium to the support, which stabilizes palladium in a more dispersed state. Because of this strong interaction, Pd2+ is stabilized in the ionic state. A change in the properties of the palladium particles initiates changes in the catalytic properties of Pd/C catalysts in the reaction of selective hydrogenation of 1,3-butadiene into butylenes. An increase in the fraction of Pd2+ in the catalyst composition results in the decrease of both total activity and selectivity of Pd/C catalysts in the considered reaction

Some problems in the study of the chronology of the ancient nomadic cultures in Eurasia (9th - 3rd centuries BC)

This research is focused on the chronological investigations of ancient nomads belonging to the Scythian cultures which occupied the steppe and forest-steppe zones of Eurasia during the 9th-3rd centuries BC. The 14C dates for the pre-scythian and early scythian time in both Europe and Asia are presented and compared to their chronological position based on archaeological evidence. The first 14C dates have been produced for the Scythian time monuments located in the Lower Volga River basin, Urals and Transurals regions. Their chronological positions are compared with the position of the monuments of Southern Siberia and Central Asia. It was shown that the nomadic cultures belonging to the Scythian culture began to exist over the wide territory of Eurasia from the 9th-8th centuries cal BC and there are some monuments which may be synchronous to the Arzhan royal barrow (the oldest monument known). A list of new 14C dates and a map of the monuments are presented

A chronology of the Scythian antiquities of Eurasia based on new archaeological and C-14 data

The paper is compares the chronology of the monuments of the Scythian epoch located in the east and west of the Eurasian steppe zone on the basis of both archaeological and radiocarbon data. The lists of C-14 dates for the monuments located in different parts of Eurasia are presented according to the periods of their existence. Generally, the C-14 dates are confirmed the archaeological point of view and allow us to compare the chronological position of the European and Asian Scythian monuments on the united C-14 time scale