Hydrogen rhenium system

The palladium-rhenium system has been little studied,and rhenium s influence on other metals hardly at all. It rapidly negated the isomerisation activity of palladium, and the reaction of neopentane with hydrogen had a maximum rate (mainly hydrogenolysis) at 50% rhenium. ... 

These dehydrogenation reactions are essentially hydrogen transfer reactions between the alkane and dimethylbutene. In the case of the rhenium system, the species 17, L2ReH3, was invoked to account for the products of the reactions of 14 with various organic substrates [38]. ITie same species L2ReH3 can also be responsible for the activation of... 

Molybdenum hexafluoride is used in the manufacture of thin films (qv) for large-scale integrated circuits (qv) commonly known as LSIC systems (3,4), in the manufacture of metallised ceramics (see MetaL-MATRIX COMPOSITES) (5), and chemical vapor deposition of molybdenum and molybdenum—tungsten alloys (see Molybdenumand molybdenum alloys) (6,7). The latter process involves the reduction of gaseous metal fluorides by hydrogen at elevated temperatures to produce metals or their alloys such as molybdenum—tungsten, molybdenum—tungsten—rhenium, or molybdenum—rhenium alloys. 

In earlier procedures, the ReO anion was precipitated from water as the relatively insoluble potassium salt. Reduction of KReO with hydrogen gas gives rhenium metal, but the metal is contaminated with ca 0.4 wt % potassium that cannot be separated easily. Although suitable for some purposes, rhenium formed from KReO is found to be unsatisfactory in appHcations such as those for use in filaments in mass spectrometer systems. The route involving NH ReO avoids this problem. 

Rhenium oxides have been studied as catalyst materials in oxidation reactions of sulfur dioxide to sulfur trioxide, sulfite to sulfate, and nitrite to nitrate. There has been no commercial development in this area. These compounds have also been used as catalysts for reductions, but appear not to have exceptional properties. Rhenium sulfide catalysts have been used for hydrogenations of organic compounds, including benzene and styrene, and for dehydrogenation of alcohols to give aldehydes (qv) and ketones (qv). The significant property of these catalyst systems is that they are not poisoned by sulfur compounds. 

Potassium-Rhenium-Hydrogen and Potassium-Technetium-Hydrogen Systems... 

On such bimetallic catalysts the rhenium loading at saturation of a 0.6% Pt/Al2C>3 catalyst depends on the hydrogen pressure. From a thermodynamic point of view the quantity of additive deposited at saturation is defined by the equilibrium conditions of the system under consideration. By taking into account the reduction of Re04 to Re0 at 303 K (Table 1),... 

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