Generating Superbasic Sites on Mesoporous Silica SBA-15

Abstract

Superbasic sites have been generated on the mesoporous silica materials for the first time, through a new strategy to prepare the MgO-modified SBA-15 in one-pot synthesis and then to disperse KNO3, possessing the good textural structure of the host and the high basic strength (H-) of 27.0. The in situ coated Mg species passivated the silanol groups on the surface of siliceous SBA-15 so that the mesostructure of SBA-15 could be reserved after the composite was loaded with KNO3 and activated at high temperature. Existence of the special protection layer of MgO on the surface of SBA-15 was also beneficial for decomposition of KNO3 to form superbasic sites on the mesoporous silica. The influence of coating amount of MgO on the protection of the textural properties of SBA-15 is examined and discussed in terms of consuming surface silanol groups. Dispersion and decomposition of KNO3 on the MgO layer is also explored. Other metal oxides such as CaO, ZnO, and Al2O3 are in situ coated on the surface of SBA-15 through one-pot synthesis and their function of protecting SBA-15 is evaluated for comparison with MgO.