Boosting the sintering resistance of platinum–alumina catalyst via a morphology-confined phosphate-doping strategy

Abstract

It is still a great challenge to develop robust sintering-resistant automotive exhaust catalysts due to the harsh working temperature, varying from ambient to >1000 °C. Here we report a strategy to simultaneously control the sintering process of both particle migration and coalescence (PMC) and Ostwald ripening (OR) by introducing non-oxides MPO₄ (M = Al, Ce, La) to the Pt–Al₂O₃ catalyst. The effects of the mix ratio, type of phosphates and their particle size on the catalysts' sintering-resistance performances were investigated. As a result, the catalyst of Pt–Al₂O₃ mixed with ball-milled LaPO₄ (LaPO₄mill) at a ratio of 2 : 1 showed the best sintering resistance. The outstanding sintering resistance of Pt–Al₂O₃–LaPO₄mill was attributed to: 1) the strong interaction between Pt and the small-sized LaPO₄, which induced an active Pt–O–La interface, 2) the mutual reinforced dual-supports with a high surface area, and 3) the confinement effect of the slim nanowire-shaped LaPO₄ grains.