Olefin oligomerization

Claim 1

In a catalytic olefin oligomerization process, the improvement which comprises employing as the catalyst a catalyst composition comprising a ferrierite of (a) the following formula: M.sub.x/n (T.sup.III O.sub.2).sub.x (Si.sup.IV O.sub.2).sub.36-x where T III represents at least one element selected from the group consisting of boron (B III ), aluminum (Al III ), gallium (Ga III ) and iron (Fe III ); X ranges from 0.05 to 6.6; M is a compensation cation; and n is the valence of M; (b) an X-ray diffraction diagram shown in Table 1 of the description; (c) a fluorine content after synthesis ranging from about 0.01 to 1.6% by weight; and (d) a Si IV /T III molar ratio of at least about 4.75; and wherein said ferrierite is produced by the steps of: (i) preparing a reaction mixture in aqueous solution at a pH lower than about 10, comprising at least one source of silicon oxide, one source of at least one oxide of trivalent metal T selected from the group consisting of boron, gallium, aluminum and iron, one source of fluorine ion F and at least one structurizing agent supplying nitrogen-containing organic cations, selected from the group consisting of primary and secondary aliphatic monoamines, diamines, triamines and ammonium cations derived by protonation of said mono-, di-, triamines, said agent having a total number of carbon and nitrogen atoms from 3 to 8, said mixture having a composition, in terms of molar ratios, ranging within the following intervals: ______________________________________ Si.sup.IV /ΣT.sup.III at least 4.75 (T.sup.III = B, Al, Ga, Fe) F.sup.- /Si.sup.IV 0.1-3 Organic structurizing 0.1-4 agent/Si.sup.IV H.sub.2 O/Si.sup.IV 4-200 ______________________________________ (ii) maintaining said mixture at a heating temperature of at most 270° C., so as to obtain crystals, and (iii) roasting said crystals at a temperature higher than 400° C.