Tungsten-sulfur compounds

Isopropyl Alcohol. Propylene may be easily hydrolyzed to isopropyl alcohol. Eady commercial processes involved the use of sulfuric acid in an indirect process (100). The disadvantage was the need to reconcentrate the sulfuric acid after hydrolysis. Direct catalytic hydration of propylene to 2-propanol followed commercialization of the sulfuric acid process and eliniinated the need for acid reconcentration, thus reducing corrosion problems, energy use, and air pollution by SO2 and organic sulfur compounds. Gas-phase hydration takes place over supported oxides of tungsten at 540 K and 25... 

Tsigdinos, G. A. Sulfur Compounds of Molybdenum and Tungsten. Their Preparation, Structure, and Properties. 76, 65-105 (1978). 

The mechanism of the catalyst activation by sulfur is not understood. The amount of sulfur compounds necessary to maintain or increase the catalyst activity depends in some cases on the stability of the heavy-metal sulfide component of the catalyst. Thus molybdenum sulfide seems to require a higher hydrogen sulfide concentration than tungsten sulfide. However, some catalysts that do not contain elements that can form sulfides under reaction conditions also showed an increased activity when sulfur compounds were added to the feed. Hydrogen sulfide in many cases decreases the catalyst sensitivity to nitrogen compounds and thus causes an activity increase. Sufficient data for pure compounds are not available to permit segregation of these effects. 

The older literature on molybdenum-sulfur chemistry describes several compounds6 that have later been shown to be either incorrectly formulated or non-existent. In recent times, the chemistry of molybdenum-sulfur compounds has been elucidated by modern techniques, both in solution and in the solid state. It is therefore the purpose of the present chapter to review and systematize the best information available in this area. Although the primary emphasis has been placed on molybdenum-sulfur species, for completeness and correlation purposes, certain tungsten or selenium analogs have also been included. 

Shibahara T. Syntheses of sulfur-bridged molybdenum and tungsten coordination compounds. Coord Chem Rev 1993 123 73-147. 

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