Reaction routes for methane conversion on transition metals at low temperature

Two new metal catalysed routes for methane conversion are discussed: methane oligomerization and methane addition to olefins. These reactions are realized in a reaction cycle consisting of several steps. In both reaction sequences methane is first dissociatively adsorbed on a reduced transition metal catalyst between 500 and 800 K resulting in surface carbon and hydrogen. A particular highly reactive surface carbonaceous intermediate is found to produce C2+ hydrocarbons upon hydrogenation between 300 and 400 K. The maximum yield for higher hydrocarbons is 13% obtained on a Ru/SiO2 catalyst. When olefins are co-adsorbed together with surface carbon generated from methane, more C2+ hydrocarbons are produced. Experiments with 13C labelled CH4 and unlabelled olefins demonstrate that surface carbon from methane is incorporated into the co-adsorbed olefins

Accumulation patterns of some seed oil components from wild sources of Turkey

Accumulation profiles of fatty acids and a-tocopherol were analysed at three ripening stages in the seed oils of Primula and Echium species. Total seed oils were increased considerably with maturation, while a-tocopherol contents decreased in both species. Increased levels of ALA and oleic acid, and decrease in linoleic and palmitic acids at late ripening stages of Primula sibthorpii, and slightly fluctuations of all examined fatty acids in Echium italicum were observed. Considerable amounts of a-tocopherol (27.4?mg/100?g), linoleic acid (42.76%) and ALA (25.46%) and GLA (4.11%) were detected in Ribes alpinum. Typical accumulation patterns of the examined parameters may be useful for species characterisation and biochemical monitoring of seed development in natural conditions

The relation between catalytic and electronic properties of supported platinum catalysts: the local density of states as determined by x-ray absorption spectroscopy

The intensity of the white line of the LII and LIII x-ray absorption edge spectra of small platinum particles increases with decreasing particle size. The combined white line intensity of the LII and LIII x-ray absorption spectra for platinum catalysts with comparable av. particle size is higher when dispersed on acidic than on neutral supports. This indicates that Pt particles are more electron deficient on acidic than on neutral supports. The propane hydrogenolysis TOF for Pt supported on g-Al2O3 or H-LTL is more than an order of magnitude higher than for Pt supported on a nonacidic K-LTL zeolite. The differences in catalytic behavior are related to differences in the d-band d. of states. [on SciFinder (R)

The reduction of nitric-oxide by hydrogen over Pt, Rh and Pt-Rh single crystal surfaces

R.A. van Santen: question, p. 35