Pt Nanoparticles Embedded in Colloidal Crystal Template Derived 3D Ordered Macroporous Ce_0.6Zr_0.3Y0.1O₂: Highly Efficient Catalysts for Methane Combustion

Three-dimensionally ordered macro/mesoporous Ce_0.6Zr_0.3Y_0.1O₂ (3DOM CZY) supported high-dispersion Pt nanoparticles (x wt % Pt/3DOM CZY, x = 0.6, 1.1, and 1.7) were successfully synthesized via the cetyltrimethylammonium bromide/triblock copolymer P123 assisted gas bubbling reduction route. The 3DOM CZY and x wt % Pt/3DOM CZY samples exhibited a high surface area of 84-94 m²/g. Pt nanoparticles (NPs) with a size of 2.6-4.2 nm were uniformly dispersed on the surface of 3DOM CZY. The 1.1 wt % Pt/3DOM CZY sample showed excellent catalytic performance, giving a T_90% value at 598 degrees ºC at gas hourly space velocity (GHSV) of 30000 mL/(g h) and the highest turnover frequency (TOF_Pt) of 6.98 X 10^-3 mol/(mol_Pt s) at 400 degrees ºC for methane combustion. The apparent activation energy (64 kJ/mol) over 1.1 wt % Pt/3DOM CZY was much lower than that (95 kJ/mol) over Bulk CZY. The effects of water vapor and SO₂ on the catalytic activity of 1.1 wt % Pt/3DOM CZY were also examined. It is concluded that the excellent catalytic activity of 1.1 wt % Pt/3DOM CZY was associated with its high oxygen adspecies concentration, good low-temperature reducibility, and strong interaction between Pt NPs and CZY as well as large surface area and unique nanovoid-walled 3DOM structure.