Alkylation of benzene with olefins in the presence of zirconium-pillared clays

Purified Brazilian montmorillonite and Wyoming clays intercalated with zirconium acetate solutions with different Zr/clay ratios were pillared and characterized by X-ray fluorescence and diffraction (XRF, XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), N-2 adsorption and temperature-programmed desorption (TPD) of NH3. The intercalation time was followed by XRD analysis. The pillarization resulted in the displacement of the low-angle diffraction pattern, indicating structural modification of the samples. The Wyoming clay presented a significant increase of the surface area for the ratio of Zr/clay = 10 (from 29 to 217 m(2)/g). The Brazilian clay, under the same pillarization conditions as the Wyoming clay, showed an increase of the surface area from 108 to 206 m(2)/g. As a result of the thermogravimetric analysis, the Brazilian clay showed a smaller thermal stability than the Wyoming natural clay. The TPD of NH3 analyses showed similar amounts of acid sites for K10 commercial acid clay, Brazilian and Wyoming-pillared clays with Zr/clay ratio of 10. The K10 commercial clay had greater activity and stability for the isomerization of 1-butene than the Brazilian and Wyoming-pillared clays. The alkylation reactions of benzene with 1 hexene, 1-octene and 1-dodecene showed greater selectivity for monoalkylated products for K10, and similar selectivities for the Brazilian and Wyoming-pillared clays, when using the olefin with longer hydrocarbon chain. As the hydrocarbon chain length was decreased, the selectivity for monoalkylated products was increased when using the Wyoming clay as compared to the Brazilian clay. (C) 2007 Elsevier B.V. All rights reserved.