Improved selectivity to C8-Olefins for isobutene oligomerization on NiO-W2O3/Al2O3 catalysts

Abstract

Isobutene oligomerization on W2O3/Al2O3 and NiO-W2O3/Al2O3 catalysts (20 wt.% W2O3 and 5 wt.% NiO) was studied. The catalysts were prepared by impregnating ammonium tungstanate and nickel nitrate on a γ-alumina sol-gel support. The XRD patterns of the samples calcined at 500°C show the presence of large W2O3 conglomerates on the W2O3/Al2O3 sample and smaller ones on the NiO-W2O3/Al2O3 catalyst. Pyridine-FT-IR absorption spectra study shows a higher acidity on the nickel-containing sample. The isobutene oligomerization was carried out in a gas-phase flow reactor (50°-150°C), and selectivity as high as 100% to the formation of the C8= olefins fraction was obtained. The role of NiO coordinating the π-allyl adsorption of the olefins as well as its role to the high C8= selectivity were discussed. © Taylor & Francis Group, LLC.