Tungsten carbide catalyzes the formation of water from hydrogen and oxygen at room temperature, the reduction of tungsten trioxide by hydrogen in the presence of water, and the isomerization of 2,2-dimethylpropane to 2-methylbutane. This catalytic behavior, which is typical of platinum, is not exhibited at all by tungsten. The surface electronic properties of the latter are therefore modified by carbon in such a way that they resemble those of platinum.

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Publication costs assisted by Exxon Research and Engineering CompanyIn an effort directed toward a more thorough comprehension of the process of intercalation of Lewis-base guests into the layered transition metal dichalcogenides, we studied the gas-solid reaction of ammonia and tantalum disulfide. The uptake and desorption were followed gravimetrically. Isotherms for (NH3)xTaS2 between 308 and 353°K and 0.65 < x < 0.85 did not show hysteresis. In this concentration range, the variation of composition with temperature at constant NH3 pressure (1 atm) shows the presence of a simple homogeneous phase. This is confirmed by X-ray diffraction. Deintercalation below x ~0.65 leads to the formation of a second-stage compound. In the single phase region, the isosteric enthalpy of intercalation increases with increasing ammonia content. This suggests strong interaction between intercalated molecules and a structure having the C3 axis of the guest parallel to the layer planes.

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