TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The hydrogenation catalyst is contacted with descending liquid phase and with an ascending vapor phase, for any catalytic bed of the inner part of the hydrogenation reaction zone. The flow of liquid to be hydrogenated is a co-current to the flow of gas stream comprising hydrogen, for any catalytic bed of the inner part of the hydrogenation reaction zone. The flow of liquid to be hydrogenated is co-current to the flow of gas stream comprising hydrogen and the distillation steam is contacting with the catalyst for any catalytic bed of the inner part of the hydrogenation reaction zone. The catalyst used in the hydrogenation reaction zone comprises at least one metal comprising nickel, zirconium or platinum. The metal is chlorinated alumina or alumina zeolite support.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The lateral removal of the effluent is carried out above or below the return line of the reaction zone. The second charge is injected with the complement injected in the inner zone of hydrogenation of the distillation column. The second charge is formed by hydrocarbons comprising 4C per molecule. The second charge is formed by: a cut C5/C6 of light naphtha of straight-run distillation and/or of type naphtha produced by hydrocracking unit; cuts enriched in benzene and/or toluene and depleted in sulfur and nitrogen obtained from catalytic cracking; gas cuts constituted of cuts enriched in benzene and/or toluene-depleted in sulfur and nitrogen obtained from viscosity reducing or coking unit; cuts enriched in benzene and/or toluene, depleted in sulfur and nitrogen obtained after cracking of olefins or oligocracking; and/or cuts rich in benzene and/or toluene, depleted in sulfur and nitrogen and obtained from unit of production of olefins by steam cracking. The distillation is performed under a pressure of 0.2-2 MPa, with a reflux rate of 0.5-10, the temperature of distillation zone head is 40-180 degrees C and the bottom temperature of the distillation zone is 120-280 degrees C. In the process, a portion of the effluent from the hydrogenation reactor is recycled at the reactor inlet. The hydrogenation reaction, performed in the hydrogenation zone internal to the distillation zone is conducted at a temperature of 100-200 degrees C, at a pressure of 0.2-2 MPa, a space velocity in the internal hydrogenation reaction zone, calculated with respect to the catalyst, of 1-50 h-1 and the flow of hydrogen feeding the hydrogenation reaction zone is 0.5-10 times the rate corresponding to the stoichiometry of involved hydrogenation reactions. The hydrogenation reaction carried out in the part external to the distillation zone is carried out at a pressure of 0.1-6 MPa, a temperature of 100-400 degrees C, a space velocity in the hydrogenation reaction zone, calculated with respect to the catalyst, usually 1-50 h-1 and a hydrogen flow rate, corresponding to the stoichiometry of involved hydrogenation reactions, of 0.5-10 times the stoichiometry. The process comprises carrying out a step of isomerization of the charge of the reaction zone sampled at the height of at least one level of sampling from the distillation zone. The isomerization step is carried out in the hydrogenation reactor at the same time as the hydrogenation reaction. The isomerization step is carried out outside the hydrogenation reactor and after the hydrogenation step. Preferred Components: The second charge is constituted of at least one charge comprising: hydrocarbons comprising 4C per molecule; a cut C5/C6 of light naphtha of straight-run distillation; a cut C5/C6 of naphtha produced by hydrocracking unit; a gasoline cut of catalytic cracking core enriched in benzene with respect to the total gasoline of catalytic cracking; a light gasoline cut from coking unit enriched in benzene with respect to the total gasoline of coking; a cut enriched in benzene obtained after separation and hydrotreatment of gasoline obtained from olefin cracking or oligocracking; and a cut rich in benzene obtained from the unit for producing olefins by steam cracking. The hydrogenation reaction zone is entirely external to the distillation zone and partially incorporated into the stripping zone of the distillation zone and partly external to the distillation area. The gas stream comprising hydrogen is attached to the vapor phase, substantially at the inlet of at least one catalytic bed of the hydrogenation reaction zone.