High surface area Au/CeO2 catalysts for low temperature formaldehyde oxidation

Gold catalysts supported on high surface area CeO2 were synthesized and tested for low temperature formaldehyde oxidation. It was found that the reactivity was greatly enhanced by increasing surface area of the support. Complete conversion of formaldehyde was obtained on a 3.0Au/CeO2-270 catalyst with a surface area of 270 m2 g−1 at 50 °C, and a conversion of 92.3% was obtained at 37 °C over the same catalyst, which made it promising for indoor formaldehyde removal. Detailed characterizations of the catalyst showed that the enhancement could be attributed to two factors. One was that Au species mainly in high oxidation states formed on the high surface area CeO2 resulted in a high degree of HCHO adsorption, as revealed by in situ diffuse reflectance infrared Fourier transform spectroscopy. The other was the high surface area CeO2 provided more oxygen vacancies by the nano effect and the formation of AuxCe1−xO2−δ solid solution as revealed by Raman spectroscopy, on which oxygen molecules could be transformed to active species for the reaction.

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► High surface area Au/CeO2 catalysts are active for formaldehyde oxidation.
► Au+ and Au3+ species provide sites for HCHO adsorption to form formate intermediates.
► AuxCe1−xO2−δ solid solution contains more oxygen vacancies for oxygen activation.