Multi-reactor hydrodesulfurization process

Abstract

An asphaltene-containing oil hydrodesulfurization process employing upstream and downstream reactors in series with an interstage flashing step. The catalyst in the downstream reactor comprises supported Group VI and Group VIII metals together with a promoting amount of Group IV-B metal. The particles of the catalyst in the downstream reactor are in the form of extrudates whose surface is provided with a plurality of alternating longitudinal grooves and protrusions. The catalyst in the upstream reactor comprises Group VI and Group VIII metals without promotion with Group IV-B metal and is in the form of particles whose surface may or may not have a similar grooved form. An advantageous mass velocity-related activity effect has been found when the downstream reactor has a diameter which is smaller than the diameter of the upstream reactor. The reduced diameter provides a concomitant advantage related to hydrogen pressure since it is shown that the reduced diameter permits the downstream reactor to withstand enhanced pressures and it is also shown that the promoted catalyst is particularly susceptible to regeneration via increases in hydrogen pressure.