Au/La-CeO_(x) catalyst for CO oxidation:Effect of different atmospheres pretreatment on gold state—Commemorating the 100th anniversary of the birth of Academician Guangxian Xu

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 Au^(3+)is transformed to Au^(δ+)(0<δ<1)during CO oxidation,which is a key step to lead to higher reactivity.For the sample after reductive atmosphere pretreatment,Au^(δ+)is mixed with a small amount of Au^(0)which can be converted to Au^(δ+)with the increase of temperature in reaction.Meanwhile,the sample always maintains high activity during the reaction.Therefore,the Au®+obtained by reductive pretreatment is more active than the Au^(3+)obtained by oxidative treatment in catalyzing CO oxidation.