Tungsten -sulfide

Phthalocyanines are excellent lubricants at temperatures of 149—343°C (191). Combinations with other lubricants, like grease, molybdenum, or tungsten sulfides, have found appHcations in the automotive industry or professional drilling equipment (192—195). Further uses include indicators for iron(Il), molybdenum(V), and uranium(IV) (196) or redox reactions (197), medical appHcations like hemoglobin replacements (198) or sterilisation indicators (199), or uses like in gas filters for the removal of nitrogen oxides from cigarette smoke (200). 

Trigonal-Prism Radii. In molybdenite and the corresponding tungsten sulfide the metal atom is surrounded by six sulfur atoms at the corners of a right trigonal prism of axial ratio unity, the bond orbitals involved being those discussed in an earlier section. Prom the observed interatomic distances the values 1.37 and 1.44 A are calculated for Mo and IPIV in such crystals (Table XV). 

Rosa Llusar was born on September 20th, 1960 in Almenara (Spain). She studied chemistry at the University of Valencia (Spain) where she graduated in 1983 with the highest honors. Her doctorate work was devoted to the chemistry of cubane-type molybdenum and tungsten sulfides and she received Ph.D. degrees from Valencia University in 1987 and from Texas A M University (USA) in 1988, under the guidance of Prof. F. Albert Cotton. After working in the Research and Development Department of a Caprolactam Production Plant in Castello (Spain) for three years, she spent one year (1992) with Prof John D. Corbett at the... 

A similar relationship can be observed with promoted M0S2. Each family of catalysts has its own linear correlation, which cannot be compared to each other directly because of the corrosivity problem. More recently, low-temperature oxygen chemisorption has been claimed to be more reliable, but it also lacks a well-determined stoichiometry (52). Oxygen chemisorption has also been applied to tungsten and rhenium sulfides, as well as promoted molybdenum and tungsten sulfides. In the isotropic class, it has been applied only to ruthenium sulfide, in which case it gives approximately the same result as a BET measurement due to the isotropic nature of this sulfide (41). 

Synthesis and characterization of novel mesostructured tungsten sulfides Charles (Chibiao) Liu and, Amy Ferryman, Julia E. Fulghum, Songping D. Huang Department of Chemistry, Kent State University, Kent, OH 44242, USA Dedicated to Dr. Richard H. Fish on the occasion of his 60th birthday... 

Three novel mesostructured tungsten sulfides, designated as MTS-W, MTS-M and MTS-C, were prepared by the condensation reaction of (NH4)2WS4 in the presence of octadecyltrimethylammonium bromide (OTAB) under refluxing conditions in water, methanol and carbon tetrachloride at 373 K, 338 K and 350 K, respectively. The three as-synthesized metal sulfides all have a layered structure with the d-spacing of 31 A, 30 A or 37 A. Partial removal of the organic surfactants from the layer galleries can be achieved by solvent extraction. 

Synthesis and structural characterization of different mesostructured tungsten sulfides... 

Therefore, the mesostructured tungsten sulfides MTS-W, MTS-M and MTS-C must consist of organic templates intercalated between condensed inorganic walls made up of layered WS2 and chain-like WS3. On the other hand. The product prepared at room temperature in aqueous solution (i.e. MTS-RT) mainly contains organic templates and discrete WS42 clusters. It should be noted that WS3is X-ray amorphous. Its presence in the mesostructured materials was further confirmed by the elemental analysis results of the products (Table 1). 

Synthesis and Characterization of Novel Mesostructured Tungsten Sulfides 383... 

Hydrocracking is catalyzed by substances that promote cracking and hydrogenation together. Nickel and tungsten sulfides on acid supports and zeolites loaded with palladium are used commercially. 

The XRD of the catalyst after 24 h on stream showed only the original W2C phase. No bulk tungsten sulfide phases were detected. The similarity in produce distribution to the Co-Mo-S/A1203 suggests that a surface sulfur layer might have formed on the carbide by reaction with the thiophene. This sulfur layer would be responsible for the reaction. 

Since the tungsten sulfide catalyst could not be used at high temperatures for the production of highly aromatic gasolines, the develop-... 

The surface (14) of the tungsten sulfide catalyst was calculated from adsorption isotherms at pressures up to 100 mm. Hg obtained at temperatures between 0° and 150°C. with argon. The method used for the... 

Adsorption measurements with other gases in Table II show that the gas adsorption on the WS2 catalyst is selective toward hydrogen and unsaturated hydrocarbons. The pretreatment of the tungsten sulfide catalyst influences the amount of hydrogen that is adsorbed. Figure 1 shows in curve I an isotherm at 0°C. with a catalyst that was degassed for... 

A tungsten sulfide catalyst which had been inactivated by extended operation had, as expected, a considerably lower adsorption capacity than new catalyst. This is shown in Fig. 3 for the adsorption of ethane at 100°C. The adsorption rate of gases on used, inactive WS2 catalyst seems to be decreased to an even greater extent. 

The adsorption experiments have shown that tungsten sulfide catalyzes the hydrogenation of olefins to paraffins at room temperature. They give, however, no indication that WS2 catalyzes other reactions. Two types of reactions are... 

Tungsten sulfide catalyst should accelerate not only the hydrogenation reactions, but also dehydrogenation of hydroaromatics to aromatics. Thermodynamic calculations show that such reactions are probable at about 500°C. at a hydrogen pressure of about 50 atm. Use of the tung-... 

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