Abstract
Uniform core-shell composites with cage-like mesoporous silica (CmesoSiO(2)) shells and zeolite HZSM-5 cores have been synthesized by a facile acid-catalyzed sol-gel coating process. The mesoporous silica shells are uniform and coated on the anisotropic HZSM-5 crystal faces, and the shell-thicknesses can be tuned from 25 to 70 nm. The core-shell composites possess a high surface area (similar to 862 m(2) g(-1)) and pore volume (similar to 0.66 cm(3) g(-1)), large pore sizes (3.2-8.2 nm) and unchanged zeolite micropore properties. The silica shells are composed of cage-like mesopores and entrances (ranging from 3.2 to 8.2 nm) as well as a plenty of micropores. Pt nanocatalysts with an average particle size of similar to 3.2 nm have been successfully encapsulated into the micropores and partial mesopores of the cage-like silica shells. The catalytic oxidation of toluene shows that the Pt/HZ@CmesoSiO(2) composite presents an equivalent activity for toluene combustion at the light-off temperature of similar to 195 degrees C (T-50%) relative to the mixture catalyst (198 degrees C of T-50%), but more excellent catalytic durability without activity loss (193 degrees C of T-50%) after a 100 h test.