Characterizations of aluminum-promoted sulfated zirconia on mesoporous MCM-41 silica: Butane isomerization
Resource
Microporous and Mesoporous Materials 110 (2-3): 260-270
Journal
Microporous and Mesoporous Materials
Journal Volume
110
Journal Issue
2-3
Pages
260-270
Date Issued
2008
Author(s)
Wang, J.-H.
Abstract
Sulfated zirconia (SZ) was supported on mesoporous molecular sieves MCM-41 by impregnation of zirconium sulfate followed by calcination. The nanochannels of MCM-41 provide a large surface area for the solid state dispersion of zirconium sulfate and a steric restriction on formation of zirconia nanoparticles. The catalysts were tested in n-butane isomerization. With the addition of a proper amount of alumina as a promoter, denoted as ASZ/MCM-41, the catalytic activity was dramatically improved in comparison to the activities of SZ/MCM-41. The increase of activity was determined primarily by the amount of aluminum added and the temperature of calcination. The SZ/MCM-41 catalysts were characterized by X-ray diffraction (XRD), high resolution TEM (HR-TEM), NH3 adsorption (NH3-TPD), X-ray photoelectron spectroscopy (XPS) and X-ray absorption (EXAFS). In particular, the Zr K-edge EXAFS data give one a measure of the degree of dispersion of zirconia on the surface of MCM-41. The trend of the promotion effects of alumina on SZ in butane isomerization is not monotonic; there is an optimum level of Al-loading for high activity. It is explained based on three quantitative factors: increased sulfur loadings, balanced distribution of Lewis and Brønsted acid sites, and higher dispersion of zirconia. © 2007 Elsevier Inc. All rights reserved.
SDGs
Type
journal article