Abstract: Liquid sulphur-containing hydrocarbon feedstock is passed through two or more hydrodesulfurization zones and connected in a series each containing a packed bed of solid sulfurized catalyst. The liquid is passed from the first zone to the next until the final zone. Make up hydrogen is supplied to a hydrodesulfurization zone (i) other than the first hydrodesulfurization zone; hydrogen-containing gas is recovered from each hydrodesulfurization zone. The first hydrodesulfurization zone is supplied with hydrogen-containing gas recovered from a subsequent hydrodesulfurization zone. Hydrogen-containing gas recovered from the first hydrodesulfurization zone is purged. Liquid material recovered from the first hydrodesulfurization zone is recycled to the inlet of the hydrosulfurization zone so as to provide diluent for admixture with liquid feedstock.

Abstract: A hydrodesulfurization process is provided for continuously effecting hydrodesulfurization of a liquid sulfur-containing hydrocarbon feedstock which comprises: (a) providing a hydrodesulfurization zone maintained under hydrodesulfurization conditions and comprising a column reactor having a plurality of reaction trays therein mounted one above another, each tray defining a respective reaction stage adapted to hold a predetermined liquid volume and a charge of a sulfided solid hydrodesulfurization catalyst therein, liquid downcomer means associated with each reaction tray adapted to allow liquid to pass down the column reactor from that tray but to retain solid catalyst thereon, and gas upcomer means associated with each reaction tray adapted to allow gas to enter that tray from below and to agitate the mixture of liquid and catalyst on that tray; (b) supplying liquid sulfur-containing hydrocarbon feedstock to the uppermost one of said plurality of reaction trays; (c) supplying hydrogen-containing gas below th