Alkylation of benzene and 1-dodecene over cerium-silicate pillared MWW zeolite

Abstract

The cerium-silicate pillared MWW zeolites are fabricated by introducing Ce species into the silica pillars within adjacent MWW layers through a liquid-phase pillaring method, and the multiple-layer structure of MWW zeolites is well maintained. However, it's found that these Ce³⁺ species can produce the Brønsted acid sites by the dissociation of water molecules owing to the electrostatic field of Ce³⁺ cations, the splitting of water molecules occurs following [Ce(H₂O)_n]³⁺_n ⇌ Ce[(OH)(H₂O)_n–1]²⁺ + H⁺ equation based on the Plank-Hirschler mechanism, leading to superior activity of resultant cerium-silicate pillared MWW zeolites in the alkylation between benzene with 1-dodecene. Moreover, the additional Ce species located in the silica pillars can be easily accessed by guest molecules due to the presence of mesopores between neighboring MWW layers, which can strongly active benzene molecules by polarization effect, and dodecyl carbenium ions are preferred to attack the carbon atoms located in activated benzene molecules, resulting in the long lifetime of cerium-silicate pillared MWW zeolites since the oligomerization of long-chain olefins is suppressed. Under harsh reaction conditions (benzene/1-dodecene = 10, WHSV = 20 h⁻¹), the optimized cerium-silicate pillared MWW zeolite shows outstanding activity (>40%) and excellent selectivity (>85%) of 2-LAB in the alkylation of benzene with 1-dodecene.