Characterization of Pt/SBA-15 prepared by the deposition–precipitation method

Mesoporous silica SBA-15 was prepared and loaded with Pt using the deposition–precipitation method (DP). The Pt loaded material was characterized by N2 sorption, and X-ray diffraction (XRD) at low scattering angles as well as XRD at wide angles, in order to monitor the impact of the metal deposition pathway on the mesoporous texture. After DP the material contains ordered mesoporous silica as well as a fraction appearing as non-ordered amorphous silica. This is most likely caused by the hydrothermal treatment involved in the DP. The material was also characterized using NIR and 29Si MAS NMR spectroscopy. The NIR results of the calcined materials indicate that the silanol groups of SBA-15 may act as anchoring groups for the metallic Pt particles. The NMR spectroscopy data shows that the Pt/SBA-15 sample prepared by the DP method posseses a better short-range regularity of SBA-15 walls as compared to the parent SBA-15. This is suggested to be caused by dissolution and possible re-precipitation of siliceous species.