Diffusion effects in SBA-15 and its plugged analogous by a deposition of metal-acetylacetonate complexes

Plugged hexagonal templated silica (PHTS) is a porous material analogous to SBA-15, which possesses extra microporous amorphous silica nanoparticles (plugs) within the mesopores. The influence of these nanoparticles in the mesopores of PHTS on the deposition of large metal-acetylacetonate complexes was investigated. TiO(acac)2 and VO(acac)2 were deposited on pure SBA-15 and PHTS using the liquid phase molecular designed dispersion (MDD) method. Thermolysis of the adsorbed complexes creates isolated metal oxide species in the channels of the support material. Chemical analysis, N2 sorption measurements, FTIR-PAS, UV-VIS diffuse reflectance and FT-Raman were used to evaluate the surface characteristics, surface coverage and final metal oxide loading. Information on important diffusion differences between SBA-15 and its plugged analogous was obtained. The size of the metal-acetylacetonate complex and the temperature during the deposition are important parameters for diffusion in PHTS and seem to be controlling the final properties of the deposited metal oxide layer and loading. Additionally, the influences of temperature variations during the synthesis were examined.