In-situ reduction-derived Pd/3DOM La0.6Sr0.4MnO3: Good catalytic stability in methane combustion

Abstract

To improve the stability of Pd-based catalysts at high temperatures, we herein report a novel strategy of first incorporating Pd to the lattice of three-dimensionally ordered macroporous La0.6Sr0.4MnO3 (3DOM LSMO) and then depositing Pd nanoparticles (NPs) on the surface of 3DOM LSMO directly by in-situ reducing 3DOM La0.6Sr0.4Mn1–xPdxO3 (3DOM LSMPdxO). Physicochemical properties of the materials were characterized by means of numerous techniques, and their catalytic activities were evaluated for the combustion of methane. Compared to the Pd-free sample, the doping of Pd was beneficial for improvement in catalytic activity, and the 3DOM LSMPd0.04O sample performed the best (T50% = 458 °C and T90% = 550 °C at a space velocity of 40,000 mL/(g h)). The in-situ reduction of the Pd-doped samples could generate the yPd/3DOM LSMO (y = 1.18–2.57 wt%) catalysts that exhibited good thermal stability and SO2-tolerant ability although their catalytic activities slightly decreased as compared to that prepared by the traditional impregnation method. The slight drop in activity of yPd/3DOM LSMO was due to the partial destroy of the LSMO perovskite after reduction at 500 °C. Among the Pd/3DOM LSMO samples, 1.18Pd/3DOM LSMO showed the best thermal stability and SO2-tolerant ability, which was attributed to the strong interaction between Pd NPs and 3DOM LSMO.