Patent ID: 7847037

Claim:
In a catalytic process for oligomerization of an olefinic feedstock containing hydrocarbon molecules having 2 to 12 carbon atoms per molecule, the improvement wherein the catalyst contains at least one modified zeolite, whereby said zeolite—before being modified—has a maximum pore opening diameter that is less than or equal to 7 Å, said catalyst being that prepared by a process comprising: a) at least one stage for introducing at least one metal that is selected from among the metals of groups VIB and VIII of the periodic table on a substrate comprising at least one protonated zeolite of a structural type selected from the group consisting of MEL, MFI, IT, NES, EUO, ERI, FER, CHA, MFS, MWW, MTT, TON and MOR, said at least one protonated zeolite being the only zeolite in the catalyst, b) at least one stage for treating said zeolite in the presence of at least one molecular compound that contains at least one silicon atom, said molecular compound having a molecular diameter that is greater than the maximum opening diameter of the pores of said zeolite, said treating comprising depositing said molecular compound on the outside surface of said zeolite in gaseous phase, and c) at least one heat treatment stage to form a layer of amorphous silica on the outside surface of the zeolite.