A catalytic composition for oligomerizing ethylene, in particular to 1-hexene,
is obtained by mixing at least one chromium carboxylate characterized in that it
also contains a free carboxylic acid in a set proportion, with at least one aryloxy
compound of an element M selected from the group formed by magnesium, calcium,
strontium and barium, with general formula M(RO)2-nXn in
which RO is an aryloxy radical containing 6 to 80 carbon atoms, X is a halogen
atom or a hydrocarbyl radical containing 1 to 30 carbon atoms and n is a whole
number that can take the values 0 or 1, and with at least one hydrocarbylaluminum
compound selected from the group formed by tris(hydrocarbyl)-aluminum compounds,
chlorinated or brominated hydrocarbylaluminum compounds and aluminoxanes.
