Fe oxide nanoparticles/Ti-modified mesoporous silica as a photo-catalyst for efficient and selective cyclohexane conversion with O-2 and solar light

摘要

We report a new, environmentally and economically friendly photocatalytic process with unprecedentedly high activity for partial cyclohexane oxidation. Mesoporous silicas containing isolated tetra-hedrally coordinated Ti and Fe oxide nanoparticles immobilized on the pore surface were synthesized by reacting SBA-15 with Ti(IV) acetylacetonate and Fe(III) acetylacetonate successively. A variety of characterizations suggested that the grafted tetrahedrally coordinated Ti species were coupled with Fe oxide nanoparticles via Ti-O-Fe bonds. The SBA-15 photocatalysts showed a high yield (up to sub-mmol) and nearly 100% selectivity for the production of cyclohexanol and cyclohexanone with molecular O-2 under solar light. The unprecedentedly high activity could be explained by the lengthened lifetime of the active Ti species by electron delocalization over Ti-O-Fe bonds and the visible light (lambda > 420 nm)-induced activity endowed by Fe oxide nanoparticles coupled to the Ti species.