TiO2 and ZrO2 crystals in SBA-15 silica: performance of Pt/TiO2(ZrO2)/SBA-15 catalysts in ethyl acetate combustion

TiO2 (40–64 wt%) and ZrO2 (48–62 wt%) were inserted in SBA-15 mesostructured silica by chemical solution decomposition or hydrolysis of the corresponding alkoxides inside the host pores. It yielded composites with 85–94% TiO2 crystallinity (anatase) and >95% crystallinity of ZrO2 (tetragonal phase). The 4.5 nm (ZrO2) or 5.0 and 8.5 nm (TiO2) nanocrystals did not block the SBA-15 pores, and their surface was fully accessible for adsorbed nitrogen or ethyl acetate molecules. After deposition of 0.3 wt% Pt the activity of Ti(Zr)O2/SBA-15 materials in ethyl acetate combustion was proportional to the surface area of the corresponding transition metal oxide nanoparticles, being a function of their loading and crystal size. The platinized composite materials displayed 1.7–3 times higher activity compared with platinum on bulk Ti(Zr)O2 oxides prepared by the same methods and two orders of magnitude higher activity relative to Pt/SBA-15 and Pt/γ-Al2O3 catalysts.