Influence of pre-added NaOH on the microstructure of Au–CeO2 catalyst and its activity for benzene oxidation

• The low-temperature activity of Au–CeO2 catalyst in benzene oxidation depended mainly on the microstructure of CeO2.
• The red-shift of F2g band of CeO2 in Raman spectroscopy presented an obvious relevance with the low-temperature activity.
• The red-shift of F2g of Au–CeO2 catalyst prepared by Adsorbed-Layer Reactor Technique changed with the amount of NaOH pre-addition in preparation.
• The doping of other metal ion could change F2g and low-temperature activity.

Au–CeO2/SiO2 catalysts were synthesized by Adsorbed-Layer Reactor Technique and characterized by TEM, XRD and Raman spectroscopy. It was found the pre-addition of NaOH changed the hydrolysis of HAuCl4 in adsorbed layer and then regulated the morphology and microstructure of Au and CeO2. In the catalysis of benzene oxidation, with the increase of pre-addition amount of NaOH, the high-temperature activity increased monotonously, which was consistent with the change of crystallite size of Au. However, the low-temperature activity presented a maximum with increase of pre-addition amount of NaOH, which was verified being agreement with the change of red-shift of F2g peak of CeO2. The results showed that the high-temperature activity depended on Au size and the low-temperature activity was affected by CeO2 microstructure. The experiment of metal ion doping offered another proof.

The low-temperature activity of benzene oxidation on Au–CeO2/SiO2 and the red-shift of F2g peak of CeO2 presented a similar tendency with increase of pre-addition amount of NaOH.Figure optionsDownload high-quality image (86 K)Download as PowerPoint slide