Enhancing Pt anti-sintering and oxidation-resistance by bifunctional silica overcoating for the long-term NO oxidation stability

For diesel oxidation catalyst (DOC), the sintering and oxidation of active Pt0 nanoparticles leads to severe deactivation during long-term operating condition. Here, we have synthesized SiO2-modified Pt/SiO2-Al2O3 (PtSiAl@Si) catalysts, and this silica coating layer not only can inhibit the migration of precious metals through physical isolation, but also restrain Pt0 oxidation by interfacial electron interaction between Pt and acid sites (SiOH-Al). Before and after hydrothermal aging, the maximum NO conversion of Pt-SiAl@Si decreased slightly by 5%, showing excellent durability. TEM and CO chemisorption unveiled that no obvious differences in Pt size between fresh and aged Pt-SiAl@Si. 1H NMR and NH3-DRIFTS confirmed that Pt-SiAl@Si possessed more Bro center dot nsted acid sites (Si-OH-Al). And the Pt-acid sites interface caused more active Pt0 by the electronic effect. This bifunctional overcoating allows a wide application in other catalytic materials for various reactions.