Hydrocarbons Hydrocracking with Sulfided Tungsten Oxide Catalys

Catalytic hydrocracking of petroleum oils, shale oils and hydrogenated coal distillates having relatively highnitrogen contents has been previously carried out at relatively severe conditions, i.e., temperatures of 400 C. or more, and at hydrogen pressures of 200 atmospheres or more, utilizing a variety of catalysts, with similar results as regards conversion, product selectivity and catalyst aging. Many of these catalysts have been found to give substantially equivalent results under these severe conditions because the large quantity of nitrogen in the feed poisons a relatively greater number of the active sites on the more active catalysts and efiectively masks some of the differences that would normally distinguish these catalysts from each other. The overall results obtained in these cases are attributable in part to the catalytic effect of the partially deactivated catalysts, but also is significant part to the non-catalytic effect of the relatively severe process conditions.

The present invention relates to activation of tungsten hydrocracking catalysts in such a way as greatly to enhance their activity and general elfectiveness for purposes of hydrocracking low-nitrogen content hydrocarbon oils. It has been found that tungsten sulfide catalysts of greatly improved activity and selectivity, and which exhibits relatively low rates of deactivation for purposes of hydrocracking hydrocarbon oil feed stocks having low-nitrogen contents, can be obtained by the use of the special sulfiding techniques of this invention. Thus, it has been found that improved tungsten sulfide catalysts are obtained by contacting tungsten oxide that has been composited with an activate, acidic, siliceous cracking support, such as a silicaalumina cracking catalyst, with hydrogen gas containing a minor proportion of a sulfiding agent at a temperature in the range of about 300 to 900 F., particularly 400 to 800 F., at an elevated pressure of Patented Dec. 27, 1966 ICC at least about p.s.i.g., particularly in the range of about 100 to 1000 p.s.i.-g., and especially about 2.00 to 600 p.s.'i.g., for a period effective to convert at least a substantial proportion of the tungsten to a sulfided form. Hydrogen sulfide is an example of a preferred sulfiding agent, but other equivalent materials containing divalent sulfur can be used. The catalysts activated as described above are especially adapted for use in hydrocracking hydrocarbon oils having a low-nitrogen content below about 15 p.p.m. and preferably below about 1 p.p.m., particularly when such hydrocracking is carried out at temperatures in the range of about 600 to 750 F. and at hydrogen partial pressures in the range of about 750 to 2000 p.s.i.g., and at liquid hourly space velocities in the range of about 0.5 to 8, preferably about 1 to 5 liquid volumes of oil per volume of catalyst per hour. However, the invention is not limited to the use of such conditions. The present invention includes the above-described method of activating the composite hydrocracking catalysts, the activated catalysts obtained therefrom, as well as methods of hydrocracking hydrocarbon oils having a low-nitrogen content in the presence of such catalysts.


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