Synthesis and characterization of Zr-SBA-15 supported tungsten oxide as a new mesoporous solid acid

摘要

A series of materials WO_3/Zr-SBA-15 were synthesized by modifying zirconium-incorporated SBA-15 mesoporous molecular sieve with various loadings of tungsten oxide, followed by calcining at different temperatures. The structures and the surface states of these materials were determined by XRD, TEM,N_2 adsorption-desorption and Raman spectroscopy, while the surface acidities were characterized by FT-IR spectroscopy of pyridine adsorption, NH_3-TPD, and the Hammett indicator method. To evaluate the catalytic activities of the prepared materials, the benzoylation of anisole was chosen as "the model reaction. All the results reveal that the synthesized samples are strong solid acids, even solid superacids under some conditions, with uniform mesoporous structure and high surface area The dispersion state of the supported WO_3, which depends on the WO_3 loading and the calcination temperature, has a direct influence on the acidity and catalytic activity of the materials. Moreover, the high acid strength is attributed to the W=O bond nature of the complex formed by the interaction between WO_3 and the surface of Zr-SBA-15.