METHOD FOR PRODUCING MIDDLE DISTILLATES IN WHICH THE FEEDSTOCK FROM THE FISCHER-TROPSCH PROCESS AND THE HYDROGEN STREAM HAVE LIMITED OXYGEN LEVELS

Producing middle distillates from a paraffinic feedstock produced by Fischer-Tropsch synthesis, comprises: hydrotreating the feedstock in the presence of hydrogen and hydrotreatment catalyst to obtain an effluent; separating at least one portion of the effluent into at least one light fraction, at least one hydrocarbon liquid effluent and at least one liquid effluent comprising water; hydroisomerizing/hydrocracking the hydrocarbon liquid effluent in the presence of a hydroisomerization/hydrocracking catalyst and a hydrogen stream; and fractionating the effluent. Producing middle distillates from a paraffinic feedstock produced by Fischer-Tropsch synthesis, comprises: hydrotreating the feedstock in the presence of hydrogen and of a hydrotreatment catalyst at a temperature of 100-450[deg] C, at a pressure of 0.5-15 MPa, to obtain an effluent, where the hydrogen is introduced into the hydrotreatment stage at a flow rate such that the hydrogen/feedstock ratio by volume is 50-10000 normal liters per liter, and at a hourly volume velocity is 0.1-10 per hour; separating at least one portion of the effluent into at least one light fraction, at least one hydrocarbon liquid effluent and at least one liquid effluent comprising water; hydroisomerizing/hydrocracking the hydrocarbon liquid effluent in the presence of a hydroisomerization/hydrocracking catalyst and of a hydrogen stream having been subjected to a purification stage in the case where the atomic oxygen content in the hydrogen stream is greater than 500 parts per million (ppm) by volume; and fractionating the effluent to obtain at least one middle distillate fraction.