Effect of poly(N-vinylpyrrolidone) ligand on catalytic activities of Au nanoparticles supported on Nb2O5 for CO oxidation and furfural oxidation.

The development of green preparation methods for acidic metal oxide supported gold catalysts is of great importance for the extensive use of gold catalysts as well as for a comprehensive understanding of gold catalysts. In this study, poly(N -vinylpyrrolidone) (PVP) was used as the stabilizer of gold colloids to deposit gold nanoparticles on an acidic metal oxide, Nb 2 O 5. The effects of the PVP ligand on the preparation of Au(-PVP)/Nb 2 O 5 and on the catalytic activities for gas-phase CO oxidation and liquid-phase furfural oxidation were investigated. As removing more ligand PVP of Au(-PVP)/Nb 2 O 5 , the catalytic activities for both CO oxidation and furfural oxidation increased. The optimal calcination temperature for Au(-PVP)/Nb 2 O 5 was determined to be 400 °C, and calcination at that temperature gave gold nanoparticles with an average size of 6.4 ± 2.5 nm and of the support of Nb 2 O 5 remained as the original crystalline structure. The temperature for 50% CO conversion (T 50%) of Au(-PVP)/Nb 2 O 5 (calcined at 400 °C) was 81 °C. In addition, Au(-PVP)/Nb 2 O 5 (calcined at 400 °C) presented 43% furfural conversion with 100% selectivity of furoic acid under a mild conditions (0.5 MPa O 2 , 40 °C) in the batch system. These results suggested that Au(-PVP)/Nb 2 O 5 is a good catalyst for both gas-phase and liquid-phase reactions. [Display omitted] • A green preparation method of Au/Nb 2 O 5 catalyst by using Au-PVP cluster. • The existence of ligand PVP on Nb 2 O 5 is good for obtaining small Au nanoparticles. • The ligand PVP inhibits both CO oxidation and furfural oxidation. • The calcination temperature of 400 °C is optimized for obtaining good Au/Nb 2 O 5. [ABSTRACT FROM AUTHOR]