Method for preparing a catalyst containing an active nickel phase distributed in a shell and a nickel-copper alloy

A process for preparing a catalyst comprising nickel and copper, in a proportion of 1% and 50% by weight of nickel element relative to the total weight of the catalyst, and in a proportion of 0.5% to 15% by weight of copper element relative to the total weight of the catalyst, and a porous alumina support, the support having a core and a crust at a periphery thereof, the nickel being distributed both over a crust at the periphery of the support, and at the core of the support, the thickness of said crust being between 2% and 15% of the diameter of the catalyst, the size of the nickel particles in the catalyst, measured in oxide form, being between 7 nm and 25 nm, said process comprises the following steps:

• a) either the porous support or the catalyst precursor obtained at the end of step d) is impregnated with a volume V1 of a butanol solution of between 0.2 and 0.8 times the total pore volume TPV of said support in order to obtain an impregnated support;
• b) the impregnated porous support obtained at the end of step a) is left to mature for 0.5 hour to 40 hours;
• c) the sequence of the following sub-steps is carried out:
• c1) either the matured impregnated porous support obtained at the end of step b), or the catalyst precursor obtained at the end of step d), is impregnated with a solution comprising at least one precursor of the nickel active phase;
• c2) optionally, the catalyst precursor obtained at the end of step c1) is dried at a temperature below 250° C.;
• d) the sequence of the following sub-steps is carried out:
• d1) either the porous support, or the matured impregnated porous support obtained at the end of step b), or the catalyst precursor obtained at the end of step c), is impregnated with at least one solution containing at least one copper precursor and one nickel precursor at a copper concentration in order to obtain, on the final catalyst, a content of between 0.5% and 15% by weight of copper element relative to the total weight of the final catalyst;
• d2) optionally, the catalyst precursor obtained at the end of step d1) is dried at a temperature below 250° C.;
• said step d) being carried out either before step a), or between steps b) and c), or after step c), it being understood that:
• i) when step d) is carried out before step a), then sub-steps c2) and d2) are compulsory;
• ii) when step d) is carried out between steps b) and c), then sub-step c2) is compulsory;
• iii) when step d) is carried out after step c), then sub-step d2) is compulsory.