Hydrotreatment process using a sequence of catalysts with a catalyst based on nickel and tungsten on a silica-alumina support

A process for the hydrotreating of a hydrocarbon feedstock, at least 50% by weight of the compounds of which exhibit an initial boiling point of greater than 300° C. and a final boiling point of less than 650° C., at a temperature of between 180° C. and 450° C., a pressure of between 0.5 and 30 MPa, an hourly space velocity of between 0.1 and 20 h and a hydrogen/feedstock ratio, expressed as volume of hydrogen, measured under standard temperature and pressure conditions, per volume of liquid feedstock, of between 50 l/l and 5000 l/l, so as to obtain a hydrotreated effluent, said process comprising:

• a) a first hydrotreating stage carried out in a first hydrotreating reaction section, employing at least one catalytic bed comprising at least one first hydrotreating catalyst, said hydrotreating reaction section being fed by at least said hydrocarbon feedstock and a gas stream comprising hydrogen, said first catalyst comprising an alumina support, an active phase consisting of nickel and molybdenum, and optionally phosphorus and/or optionally an organic compound containing oxygen and/or nitrogen and/or sulfur, and
• b) a second hydrotreating stage carried out in a second hydrotreating reaction section, employing at least one catalytic bed comprising at least one second hydrotreating catalyst, said hydrotreating reaction section being fed by at least a part of the effluent obtained in stage a), said second catalyst comprising a silica-alumina support, an active phase consisting of nickel and tungsten, phosphorus, and an organic compound containing oxygen and/or nitrogen and/or sulfur.