Facile Fabrication of Small-Sized Palladium Nanoparticles in Nanoconfined Spaces for Low-Temperature CO Oxidation

Palladium (Pd)-containing catalysts have gained extensive attention because of their outstanding activity in various heterogeneous catalytic reactions. The activity of these catalysts highly correlates with the size of the Pd particles. Herein, nano-sized Pd particles were fabricated by utilizing the as-made SBA-15 (AS) possessing nanoconfined spaces between the template P123 and silica walls. By using the inherent nanoconfined spaces in AS, Pd nanoparticles with a smaller size can be generated conveniently (yielding Pd-AS); in contrast, Pd is apt to aggregate and form larger-sized particles in the conventionally calcined SBA-15 (CS) without nanoconfined spaces (yielding Pd-CS). The smaller size of Pd nanoparticles in Pd-AS endows the catalysts with better catalytic activity in CO oxidation compared to their Pd-CS counterparts. On the typical sample 5Pd-AS with 5 wt % of Pd, the turnover frequency at 140 °C is 1.55 min-1, which is superior to its analogue 5Pd-CS (0.22 min-1).