Firstly - It is relatively difficult to characterize the position and coordination of Al atoms in/or SBA-15 framework by conventional technique (XRD, UV-vis ...).
We tried to prepare the Al-SBA-15 by direct synthesis with different Si/Al ratio. Up to Si/Al we did not observe the XRD pattern of Al2O3 and at the same time we observed the N2 ads/des isotherms typical for SBA-15 structure. Is it sufficient proof for successful incorporation of Al to SBA-15 framework?