Au/La-CeOx catalyst for CO oxidation: Effect of different atmospheres pretreatment on gold state ― Commemorating the 100th anniversary of the birth of Academician Guangxian Xu

Abstract

So far, it is still a controversial issue which status of gold species is a better active site for catalyzing CO oxidation. Herein, the influence of the different atmospheres pretreatment (oxidative and reductive) on gold state of Au/La-CeOx (1 wt% gold loading) catalyst during CO oxidation was studied. The changes of Au species were monitored by combined in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) and X-ray photoelectron spectroscopy (XPS). For the sample pretreated with oxidative atmosphere, the data show that the initial Au3+ is transformed to Auδ+ (0 < δ < 1) during CO oxidation, which is a key step to lead to higher reactivity. For the sample after reductive atmosphere pretreatment, Auδ+ is mixed with a small amount of Au0 which can be converted to Auδ+ with the increase of temperature in reaction. Meanwhile, the sample always maintains high activity during the reaction. Therefore, the Auδ+ obtained by reductive pretreatment is more active than the Au3+ obtained by oxidative treatment in catalyzing CO oxidation.