Investigation of catalytic mechanism of formaldehyde oxidation over three-dimensionally ordered macroporous Au/CeO2 catalyst

Novel 3DOM Au/CeO2 catalysts were created via a colloidal crystal template method coupled with a precursor complexion process, and their catalytic mechanism for enhanced HCHO catalytic oxidation was revealed in detail. [Display omitted] ► 3DOM Au/CeO2 catalyst was created via a colloidal crystal template method coupled with a precursor complexion process. ► The catalytic mechanism of the catalyst for enhanced HCHO catalytic oxidation was revealed in detail. ► The weak absorption ability of CO2 and the existence of Au active species in ionic and metal states in 3DOM Au/CeO2 catalyst improve the catalytic activity. ► The carbonate and hydrocarbonate formed on the surface of 3DOM Au/CeO2 catalyst may account for its deactivation. A colloidal crystal template method coupled with a precursor complexion process was developed to create three-dimensionally ordered macroporous (3DOM) Au/CeO2 catalyst. The resultant Au/CeO2 catalyst possesses well-defined 3DOM structure, and shows enhanced catalytic performance for formaldehyde (HCHO) oxidation with 100% HCHO conversion at ∼75°C. The catalytic mechanism of HCHO catalytic oxidation over 3DOM Au/CeO2 catalyst was systematically investigated by means of gas chromatograph (GC), H2-temperature programmed reduction (H2-TPR), temperature programmed surface reaction (TPSR), CO2-temperature programmed desorption (TPD), and Fourier transform infra-red (FT-IR) spectroscopy. GC results indicate that HCOOH intermediate is generated during HCHO catalytic oxidation. TPD and TPSR tests show that the weak absorption ability of CO2 over 3DOM Au/CeO2 catalyst and the existence of Au active species in ionic and metallic states in 3DOM Au/CeO2 catalyst largely improve the catalytic activity, favoring the enhanced HCHO catalytic oxidation. FT-IR tests prove that the carbonate and hydrocarbonate formed on the surface of 3DOM Au/CeO2 catalyst during HCHO catalytic oxidation may account for its deactivation. Based on the above investigation, a new catalytic mechanism of enhanced HCHO catalytic oxidation over 3DOM Au/CeO2 catalyst is proposed. The mechanism may afford the scientific guidance for preparing high efficiency oxide supported noble metal catalysts and present a solution for solving their deactivation problem.