MESOPOROUS CATALYST FOR HYDROTREATING PETROLEUM RESIDUE AND PREPARATION METHOD THEREOF

The invention concerns the preparation of a catalyst comprising: - a predominantly calcined aluminium oxide support; - a hydro-dehydrogenating active phase comprising at least one metal from group VIB, optionally at least one metal from group VIII, optionally phosphorus, said catalyst having: - a specific surface area Sbet greater than 75 m2/g, - a total porous volume greater than or equal to 0.55 ml/g, - a mesoporous median diameter greater than or equal to 16 nm, - a mesoporous volume greater than or equal to 0.50 ml/g, - a macroporous volume less than 15% of the total porous volume; said method comprising at least: a) a first step of precipitating at least one basic precursor and at least one acid precursor, at least one of the two comprising aluminium, at a pH of between 8.5 and 10.5, with a rate of progress of the first step of between 5 and 13%, at a temperature of between 20 and 90°C and for 2 to 30 minutes; b) a step of heating, c) a second step of precipitation by adding, into the suspension, at least one basic precursor and at least one acid precursor in which at least one of the basic or acid precursors comprises aluminium, with a pH of between 8.5 and 10.5 and a rate of progress of the second step of between 87 and 95%, d) a filtering step; e) a drying step, f) a shaping step, g) a heat treatment step; h) a step of impregnating the hydro-dehydrogenating active phase on the support obtained in step g). The invention finally concerns the mesoporous catalyst obtained and the use of same in methods for the hydrotreatment or hydroconversion of heavy hydrocarbon feedstocks.