H3PW12O40 supported on mesoporous MCM-41 and Al–MCM-41 materials: preparation and characterisation
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MCM-41 and Al–MCM-41 has been synthesized using cetyl-trimethylammonium bromide (CTAB) surfactant as template and adding the silica precursor to aqueous solutions containing CTAB. The obtained solids were calcined at 600 °C for 4 h. HPW heteropolyacid supported on the mesoporous were prepared using the incipient wetness method. The characterization of materials was performed by X-ray diffraction, Transmission Electron Microscopy, N2 adsorption, 29Si Cross Polarization–Magic Angle Spinning and 27Al MAS NMR. Results showed that the hexagonal structure is obtained in both cases. The Aluminium species are located inside an extra-framework. The impregnation reduces the surface area of the mesoporous materials especially of the Al–MCM-41 suggesting a participation of aluminium during the impregnation. HPW is well dispersed in the mesoporous materials and is located inside the pores interacting with the silanol group of the pores wall. 27Al MAS NMR measurements have showed that the impregnation causes the removal of the non-framework aluminium.
KeywordsMagic Angle Spinning H3PW12O40 Aluminium Species 27Al Nucleus Pore Wall Thickness
This study was made with the financial support of the Bulgarian Ministry of Education, Fund “SCIENTIFIC RESERCH” (project no. DPOSTDOC 02/5-2010). NMR and TEM–EDS experimental data were provided by Centro Grandi Apparecchiature—UniNetLab—Università di Palermo funded by P.O.R. Sicilia 2000–2006, Misura 3.15 Azione C Quota Regionale.
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