%0 Journal Article
%T Keggin Structure and Surface Acidity of 12-Phosphotungstic Acid Grafted Zr-MCM-48 Mesoporous Molecular Sieves
%A Zhiqi Wang
%A Juan Navarrete
%J World Journal of Nano Science and Engineering
%P 134-141
%@ 2161-4962
%D 2012
%I Scientific Research Publishing
%R 10.4236/wjnse.2012.23017
%X A zirconium modified MCM-48 mesoporous material was synthesized by surfactant-templated method. Surface grafting Zr-MCM-48 with tungstophosphoric acid led to a great enhancement of both the number of the Br?nsted acid sites and acidity strength in comparison with the bare support. At 100¡ãC, the 30 wt% H<sub>3</sub>PW<sub>12</sub>O<sub>40</sub>/Zr-MCM-48 contained 174 ¦Ìmol/g Br?nsted acid sites which were 14.5 times greater than that of Zr-MCM-48. The <i>Keggin</i> structure of the grafted heteropolyacid was rather stable after calcination at 400¡ãC for 2 h, approximately 93.3% of <i>Keggin</i> structure in the dispersed heteropolyacid were remained without destruction but slightly distorted in some degree, as evidenced by FTIR characterization and <sup>31</sup>P NMR-MAS analysis. This H<sub>3</sub>PW<sub>12</sub>O<sub>40</sub>/Zr-MCM-48 solid with three dimensional mesoporous system, large surface area and very strong Br?nsted acidity will be a promising catalyst for acid catalytic reactions.
%K Zr-MCM-48
%K Surface Acidity
%K Heteropolyacid
%K Spectroscopic Characterization
%U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=23166