Large-Pore Mesoporous CeO2 -ZrO2 Solid Solutions with In-Pore Confined Pt Nanoparticles for Enhanced CO Oxidation.

Abstract

Active and stable catalysts are highly desired for converting harmful substances (e.g., CO, NOx ) in exhaust gases of vehicles into safe gases at low exhaust temperatures. Here, a solvent evaporation-induced co-assembly process is employed to design ordered mesoporous Cex Zr1- x O2 (0 ≤ x ≤ 1) solid solutions by using high-molecular-weight poly(ethylene oxide)-block-polystyrene as the template. The obtained mesoporous Cex Zr1- x O2 possesses high surface area (60-100 m2 g-1 ) and large pore size (12-15 nm), enabling its great capacity in stably immobilizing Pt nanoparticles (4.0 nm) without blocking pore channels. The obtained mesoporous Pt/Ce0.8 Zr0.2 O2 catalyst exhibits superior CO oxidation activity with a very low T100 value of 130 °C (temperature of 100% CO conversion) and excellent stability due to the rich lattice oxygen vacancies in the Ce0.8 Zr0.2 O2 framework. The simulated catalytic evaluations of CO oxidation combined with various characterizations reveal that the intrinsic high surface oxygen mobility and well-interconnected pore structure of the mesoporous Pt/Ce0.8 Zr0.2 O2 catalyst are responsible for the remarkable catalytic efficiency. Additionally, compared with mesoporous Pt/Cex Zr1- x O2 -s with small pore size (3.8 nm), ordered mesoporous Pt/Cex Zr1- x O2 not only facilitates the mass diffusion of reactants and products, but also provides abundant anchoring sites for Pt nanoparticles and numerous exposed catalytically active interfaces for efficient heterogeneous catalysis.