Structural Design of Pd/SiO2@Ti-Containing Mesoporous Silica Core-Shell Catalyst for Efficient One-Pot Oxidation Using in Situ Produced H2O2

This study reports the importance of the structural design of heterogeneous catalysts for one-pot reaction. A series of core-shell catalysts were synthesized that consisted of SiO2 core, Pd nanoparticles (NPs), and Ti-containing mesoporous silica (Ti-MS) shell with precise control of the Pd NPs positions, the mesopore diameter, and the thickness of the Ti-MS shell The catalytic potentials were evaluated for one-pot oxidation reactions involving the direct synthesis of hydrogen peroxide (H2O2) from H-2 and O-2 gases by the Pd NPs and the subsequent oxidation reaction of sulfide by the isolated Ti-IV species using in situ produced H2O2 in the mesoporous silica. The precise architecture of the core-shell catalyst significantly enhanced the catalytic performance by a factor of 20, and the catalyst exhibited excellent activity and selectivity toward suffoxide as compared to the commonly employed Pd-supported/Ti-zeolite (Pd/TS-1) catalyst. This result provides a new perspective of heterogeneous catalysts aimed at developing environmentally benign chemical processes.