Processes, catalysts, and reactor systems for reforming heavy aromatic compounds (C.sub.11+) into C.sub.6-8 aromatic compounds are disclosed. Also disclosed are processes, catalysts, and reactor systems for producing aromatic compounds and liquid fuels from oxygenated hydrocarbons, such as carbohydrates, sugars, sugar alcohols, sugar degradation products, and the like.

Catalyst comprising nickel and sulfur on an alumina support, said catalyst being characterized in that: the nickel is distributed both on a crust at the periphery of the support, and in the core of the support, the thickness of said crust being between 2% and 15% of the diameter of the catalyst; the nickel density ratio between the crust and the core is strictly greater than 3; said crust comprises more than 25% by weight of nickel element relative to the total weight of nickel contained in the catalyst, the size of the nickel particles in the catalyst, measured in oxide form, is between 7 and 25 nm.

Catalyst comprising nickel and sulfur on an alumina support, said catalyst being characterized in that: the nickel is distributed both on a crust at the periphery of the support, and in the core of the support, the thickness of said crust being between 2% and 15% of the diameter of the catalyst; the nickel density ratio between the crust and the core is strictly greater than 3; said crust comprises more than 25% by weight of nickel element relative to the total weight of nickel contained in the catalyst, the size of the nickel particles in the catalyst, measured in oxide form, is between 7 and 25 nm.

A process for preparing a catalyst comprising an active nickel phase and an alumina support, said catalyst comprising between 1% and 50% by weight of elemental nickel relative to the total weight of the catalyst, the nickel being distributed both over a crust at the periphery of the support, and at the core of the support, which process comprises the following steps: a) said support is impregnated with a volume V1 of a hexanol 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 support obtained at the end of step a) is impregnated with a solution comprising a precursor of the nickel active phase in order to obtain a catalyst precursor; c) the catalyst precursor obtained at the end of step b) is dried at a temperature below 250? C.

A process for preparing a catalyst comprising an active nickel phase and an alumina support, said catalyst comprising between 1% and 50% by weight of elemental nickel relative to the total weight of the catalyst, the nickel being distributed both over a crust at the periphery of the support, and at the core of the support, which process comprises the following steps: a) said support is impregnated with a volume V1 of a hexanol 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 support obtained at the end of step a) is impregnated with a solution comprising a precursor of the nickel active phase in order to obtain a catalyst precursor; c) the catalyst precursor obtained at the end of step b) is dried at a temperature below 250? C.

Process for preparing a catalyst comprising a nickel active phase and an alumina support, said catalyst comprising between 1% and 50% by weight of elemental nickel relative to the total weight of the catalyst, the nickel being distributed both over a crust at the periphery of the support, and at the core of the support, which process comprises the following steps: a) said support is impregnated with a volume V1 of a heptanol 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 support obtained at the end of step a) is impregnated with a solution comprising a precursor of the nickel active phase in order to obtain a catalyst precursor; c) the catalyst precursor obtained at the end of step b) is dried at a temperature below 250? C.

Process for preparing a catalyst comprising a nickel active phase and an alumina support, said catalyst comprising between 1% and 50% by weight of elemental nickel relative to the total weight of the catalyst, the nickel being distributed both over a crust at the periphery of the support, and at the core of the support, which process comprises the following steps: a) said support is impregnated with a volume V1 of a heptanol 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 support obtained at the end of step a) is impregnated with a solution comprising a precursor of the nickel active phase in order to obtain a catalyst precursor; c) the catalyst precursor obtained at the end of step b) is dried at a temperature below 250? C.

Disclosed is a method for providing improved hydrogenation activity by pretreating a catalyst in a three-step manner before selective hydrogenation of unsaturated hydrocarbons in an aromatic fraction in the presence of an oxide-type bimetallic (particularly nickel-molybdenum) supported catalyst.

Disclosed is a method for providing improved hydrogenation activity by pretreating a catalyst in a three-step manner before selective hydrogenation of unsaturated hydrocarbons in an aromatic fraction in the presence of an oxide-type bimetallic (particularly nickel-molybdenum) supported catalyst.

Catalyst comprising a nickel-based active phase and an alumina support, characterized in that: the nickel is distributed both on a crust at the periphery of the support, and in the core of the support, the thickness of said crust being between 2% and 15% of the diameter of the catalyst; the nickel density ratio between the crust and the core is strictly greater than 3; said crust comprises between 40% and 80% by weight of nickel element relative to the total weight of nickel contained in the catalyst.