Effects of Calcination Temperature on the Catalytic Activity of Au/TiO2 in Guaiacol Hydrodeoxygenation

A series of Au/TiO2 catalysts, calcined at various temperatures, were prepared by deposition-precipitation method, and evaluated by guaiacol (Lignin compound) hydrodeoxygenation reaction. The prepared catalysts were characterized by TEM, XPS, XRD, N2 adsorption-desorption, ICP and NH3-TPD methods. Results reveal that the average particle sizes of Au on the catalysts grow up from 2.7 nm to 7.9 nm along with the calcination temperature increasing from 350 ℃ to 650 ℃. TiO2 retains in the form of anatase type, accompanied by the decrease of the surface area of the catalysts from 90 m2/g to 49 m2/g. Metallic Au species exist in both the fresh and spent catalysts. The calcination temperatures of Au/TiO2 catalysts have negligible effect on the phenolic-product selectivity. When the catalysts with the mean diameter of Au particle size is less than 6 nm, methane is formed from the methoxyl group of guaiacol. The results of different temperature and H2 pressure highlight that Au/TiO2 shows high activity to break only one C-O bond of guaiacol, without excessive hydrogenation saturation of π bond the benzene ring and dissociation of the C=C bond. Furthermore, recycle reactions over Au/TiO2 show that the conversion and product yield remain constant during two successive runs, indicating the good recyclability of the catalyst. © 2020, Editorial Office of Acta Petrolei Sinica(Petroleum Processing Section). All right reserved.