Size of Pt Nanoparticles Determines the Effect of Steam Treatment on Their Performance for Catalytic CO Oxidation

CO oxidation catalyzed by Pt group metal nanoparticle catalysts is an important reaction in many fields, such as the operation of fuel cells and automotive exhaust gas alleviation. However, improving resistance to poisoning by H2O or CO2, which are present in feed gas or exhaust gas, is still a great challenge for Pt catalysts. Herein, by employing hexaaluminate (BaFeAl11O19, denoted as H) as a support, a correlation between the size of Pt nanoparticles and the effect of steam treatment (7 vol % H2O, 500 °C 1 h) was found. The aged Pt nanoparticle catalysts with a size above 1.0 nm (1Pt/H-A) exhibited enhanced catalytic activity, cycling stability, and resistance to H2O and CO2 poisoning in CO oxidation compared with the fresh counterpart (1Pt/H). By contrast, there was a negligible change in physicochemical properties and catalytic performance over Pt nanocluster catalysts (<1.0 nm) before and after the treatment (0.5Pt/H vs 0.5Pt/H-A). Such a promoting effect can be attributed to enhanced metal–support interaction after the steam treatment, which induced an electronic effect on Pt nanoparticles and improved oxygen reactivity for CO oxidation.