Trimerization of isobutene over WOx/ZrO2 catalysts

Trimerization of isobutene to produce isobutene trimers has been investigated over WOx/ZrO2 catalysts that were obtained by wet-impregnation and successive calcination at high temperatures. Very stable isobutene conversion and high selectivity for trimers are attained over a WOx/ZrO2 catalyst obtained by calcination at 700 degrees C. From the XRD study it can be understood that tetragonal ZrO2 is beneficial for stable performance; however, monoclinic ZrO2 is not good for trimerization. Nitrogen adsorption and FTIR experiments suggest that amorphous WOx/ZrO2 is inefficient catalyst even though it has high surface area and high concentration of acid sites. The observed performance with the increased selectivity and stable conversion demonstrates that a WOx/ZrO2 having tetragonal zirconia, even with decreased porosity and acid sites, is one of the best catalysts to exhibit stable and high conversion, high selectivity for trimers and facile regeneration. (C) 2009 Elsevier B.V. All rights reserved.