Patent ID: 7658836

Claim:
An improved process of producing middle distillates, comprising subjecting a paraffinic feed having a content of solid mineral particles as well as olefinic and unsaturated compounds, and oxygen-containing compounds said feed having been produced by a Fischer-Tropsch synthesis, to a catalytic hydrocracking/hydroisomerization step, and upstream of said hydrocracking/hydroisomerization step, subjecting said paraffinic feed to a step for hydrotreatment and purification and/or decontamination, comprising passing said paraffinic feed over at least one multi-functional guard bed comprising at least one first hydrotreatment catalyst having the following characteristics: a macroporous mercury volume for a mean diameter of 50 nm which is more than 0.1 cm 3 /g; and a total volume of more than 0.60 cm 3 /g, said hydrotreatment step resulting in a reduction of the content of said solid mineral particles and in a reduction of the amount of olefinic and unsaturated compounds and oxygen-containing compounds, said solid particles being accommodated and removed by a macroporous volume of the at least one first hydrotreatment catalyst, in which the at least one first hydrotreatment catalyst is impregnated with a hydrodehydro genating active phase, and in which the guard bed comprises at least one second hydrotreating catalyst having the following pore distribution: a mercury volume for a pore diameter of more than 1 micron of more than 0.5 cm 3 /g; and a mercury volume for a pore diameter of more than 10 microns of more than 0.25 cm 3 /g.