Abstract: A multiple stage hydrodesulfurization process is described for the catalytic hydrodesulfurization and hydrodemetallization of a residual petroleum oil boiling above the gasoline range to prepare a zeolite riser cracking feed. The product of the hydrodesulfurization section comprises essentially material boiling above the gasoline range and comprises little material boiling within the gasoline range in order to preserve the feed for subsequent cracking to gasoline without added hydrogen. The hydrodesulfurization-demetallization section comprises an initial stage involving relatively high hydrogen pressure in the presence of a catalyst comprising a relatively low proportion of catalytically active hydrogenation metals. The process employs a final stage in series employing a relatively lower hydrogen pressure and a catalyst comprising a relatively higher proportion of hydrogenation metals.

Abstract: The hydrodesulfurization of a crude oil or a reduced crude containing the asphaltene fraction proceeds at unexpectedly low temperatures by utilizing a Group VI and Group VIII metal containing catalyst on alumina when the catalyst particles are very small and have a diameter between about 1/20 and 1/40 inch and are disposed in a parallel catalyst bed system.

Abstract: The hydrodesulfurization of a crude oil or a reduced crude containing the asphaltene fraction proceeds at unexpectedly low temperatures by utilizing a catalyst comprising a Group VI and Group VIII metal on alumina when the catalyst particles are very small and have a diameter between about 1/20 and 1/10 inch and the reaction is quenched with hydrogen.