Fischer-Tropsch synthesis process comprising a catalyst prepared by addition of an organic compound in gas phase

A Fischer-Tropsch process for preparing a catalyst and synthesizing hydrocarbons using the catalyst, which comprises:

• preparing the catalyst by the following steps:
• a) providing a porous support containing silica, alumina, and at least one partial or non-partial single spinel phase MAl2O4 or mixed spinel phase MxM′(1-x)Al2O4 in which M and M′ are distinct metals selected from the group consisting of magnesium (Mg), copper (Cu), cobalt (Co);
• nickel (Ni), tin (Sn), zinc (Zn), lithium (Li), calcium (Ca), caesium (Cs), sodium (Na), potassium (K), iron (Fe), and manganese (Mn) and in which x is between 0 and 1, the values of 0 and 1 themselves being excluded;
• b) adding at least one organic compound containing oxygen and/or nitrogen and comprising one or more chemical functions selected from the group consisting of carboxylic, alcohol, ester, amine, amide, ether, dilactone, carboxyanhydride, aldehyde, ketone, nitrile, imide, oxime and urea functions, but not comprising sulfur, to the porous support;
• c) bringing said porous support into contact with at least one solution containing at least one salt of a precursor of the phase comprising at least one Group VIII metal selected from the group consisting of iron (Fe) and cobalt (Co);
• d) drying the porous support obtained at the end of step c);
• wherein step b) is carried out before or after steps c) and d) and is carried out by bringing together said porous support with a porous solid comprising said at least one organic compound containing oxygen and/or nitrogen under conditions of temperature, pressure and duration such that a fraction of said organic compound is transferred in the gaseous state from said porous solid to the porous support;
• and
• using the catalyst obtained from the above steps to prepare hydrocarbons by bringing the catalyst into contact with a feedstock comprising synthesis gas under a total pressure of between 0.1 and 15 MPa, under a temperature of between 150 and 350° C., at an hourly space velocity of between 100 and 20,000 volumes of synthesis gas per volume of catalyst per hour and with an H2/CO molar ratio of the synthesis gas of between 0.5 and 4.