Highly linear octene isomers can be produced from n-butene on industrial scale by using Ni-containing aluminosilicates as heterogeneous catalysts. These catalysts can be prepared by impregnating an aluminosilicate with a Ni(II) salt solution. This leads to a competition between acid-catalyzed and nickel-catalyzed reactions. In this study it is shown that some octene isomers are exclusively formed via an acid-catalyzed mechanism as a result of methyl group migration at the surface of a mesoporous catalyst. Specifically, the isomers 4,4-dimethylhexene (4,4-DMH) and 3-ethyl-2-methylpentene (3E-2MP) exhibit a systematic correlation compared to the amount of 3,4-dimethylhexene (3,4-DMH) formed at acid sites. By analyzing the ratio of 4,4-DMH and/or 3E-2MP to 3,4-DMH in the product spectrum before and after impregnation with a nickel precursor, the extend of acid site covered by nickel ions can be evaluated.

Nickel modified mixed-phase catalysts containing both mesoporous Al-MCM-41 and microporous ZSM-5 phases were synthesized via a one-pot synthesis. By varying the composition of the catalysts, optimum values regarding Si/Al ratio and nickel content for a highly selective dimerization of n-butenes were identified. An interaction of nickel sites with vicinal aluminum or acid sites can be assumed, since a correlation between Ni/(Al + Ni) ratio, catalytic activity and selectivity was found. Novel approaches to evaluate the contribution of the cationic or coordinative reaction mechanism to the overall reaction course are proposed.

The acidic properties of a selected SiO ₂ –Al ₂ O ₃ support material have been modified by steam-treating to study the influence on the formation of active nickel sites for butene oligomerization.