Facile tailoring of hierarchical mesoporous AlSBA-15 by ionic liquid and their applications in heterogeneous catalysis

Abstract

Significant enhancement in the performance of incorporation of high content of aluminum within hierarchical mesoporous SBA-15 has been achieved by direct route using urea tetrachloroaluminate ionic liquid as novel aluminum source. The fabricated materials were fully characterized by N2 sorption isotherms, powder X-ray diffraction (XRD), FT-IR, 27Al MAS NMR, XRF, HRTEM and FESEM. The acidic properties of these materials have been examined using NH3-TPD. The catalytic performance was investigated using cumene cracking and the esterification reaction as a probe molecules to estimate the acidity of the material. It is worth noting that the ionic liquid with accomplished Al–O–Si bonds is an efficient precursor to synthesis AlSBA-15 with high aluminum content (nSi/mAl = 7) without destroying the structural order of the material in acidic medium. 27Al MAS NMR spectra of AlSBA-15 show that all aluminum species were incorporated into the SBA-15 framework with nSi/mAl ratio up to 7. Overall, this work emphasize that the AlSBA-15 materials contain Bronsted and Lewis acid sites with medium acidity which makes them adequate to be adopted as acid catalysts in heterogeneous catalysis.