Investigations of Al-Doped LP-SBA-15 Periodic Mesoporous Silica Treated in Aqueous Fluids to High Temperatures and Pressures

Doping mesoporous silica with aluminum can enhance catalytic and structural properties in the material and make the material better suited for such uses as catalysis, sorption, or photovoltaics. Aluminum can replace silicon in the SiO2 matrix when it is hydrothermally reacted and alter the material properties of the mesoporous material. Large pore SBA-15 mesoporous silica was hydrothermally treated to approximately 100 oC to cause doping with Al. The results showed that the hydrothermal treatment leaves the LP-SBA-15 pore structure unchanged whereas Al doping imparts some degree of pore-structure alteration of the material. Raman measurements showed that there is not significant change to the surface structure upon hydrothermal treatment and/or Al surface doping. SEM images showed that the pore structure is largely unchanged after doping and hydrothermal treatment of SBA-15 silica. Photoluminescence measured from the sample indicates that oxygen vacancies may have been created and a shift in peak locations is caused after hydrothermal treatment and Al surface-doping of the SBA-15 silica. SAXS data showed a slight increase in pore unit cell size and a suppressed first diffraction peak. EDS data indicated the presence of aluminum in the SBA-15 sample after hydrothermal treatment