Preparation, characterization, and catalytic performance of PdPt/3DOM LaMnAl11O19 for the combustion of methane

Abstract

Three-dimensionally ordered macroporus LaMnAl11O19 (3DOM LMAO) and its supported Pd, Pd–Pt, and Pt nanoparticles were prepared using the polymethyl methacrylate-templating and polyvinyl alcohol-protected reduction methods, respectively. The 1100 °C-calcined 3DOM LMAO support possessed a hexaaluminate phase, and its supported noble metal samples displayed a high surface area of 26–29 m2/g. A Pd–Pt alloy was generated in the PdPt/3DOM LMAO samples, and the particle sizes of the noble metal nanoparticles (NPs) were 3–5 nm. The 0.97 wt% Pd/3DOM LMAO (0.97 P d/3DOM LMAO) sample possessed the highest surface adsorbed oxygen concentration and the best low-temperature reducibility, showing the highest catalytic activity (T10% = 259 °C, T50% = 308 °C, and T90% = 343 °C at SV = 20,000 mL/(g h)) for methane combustion. The 1.14 wt% Pd2.8Pt/3DOM LMAO (1.14Pd2.8Pt/3DOM LMAO) sample performed the best (T10% = 284 °C, T50% = 372 °C, and T90% = 456 °C at SV = 20,000 mL/(g h)) among the PdPt/3DOM LMAO samples. Doping of Pt to the Pd-based catalyst could improve the H2O-, CO2-, and SO2-resistant ability without significant influence on thermal stability, although 1.14Pd2.8Pt/3DOM LMAO was less active than 0.97 P d/3DOM LMAO for methane combustion. The ex situ X-ray photoelectron spectroscopy was used to explore the formation of active PdO species during the oxidation processes of Pd in 1.14Pd2.8Pt/3DOM LMAO and 0.97Pd/3DOM LaMnAl11O19 at different temperatures.