Abstract: The invention concerns a process for producing middle distillates from an effluent produced by a Fischer-Tropsch unit, comprising optional fractionation to obtain at least one heavy fraction with an initial boiling point in the range 120-200° C., said heavy fraction or said effluent optionally being hydrotreated, then bringing it into contact with a first amorphous hydrocracking/hydroisomerization catalyst that contains at least one noble group VIII metal, the effluent obtained is distilled, then the residual fraction boiling above the middle distillates and/or a portion of the middle distillates is brought into contact with a second amorphous hydrocracking/hydroisomerization catalyst containing at least one noble group VIII metal. The invention also concerns a unit.

Abstract: A system comprising: a paraffin feed produced by the Fischer-Tropsch process is fractionable into at least three fractions: an intermediate fraction boiling between T1 and T2, T1 being in the range 120–200° C. and T2 being more than 300° C. and less than 410° C., a light fraction boiling below it and a heavy fraction boiling above it; at least a portion of the intermediate fraction is hydrotreated then at least a portion thereof is passed over an amorphous hydroisomerisation/hydrocracking catalyst; the heavy fraction is passed over an amorphous hydroisomerisation/hydrocracking catalyst with a conversion of 370° C.+ products into 370° C.? products of more than 80% by weight; the hydrocracked/hydroisomerised fractions are distilled to obtain middle distillates (kerosine, gas oil).