Hydrodeoxygenation of Guaiacol Catalyzed by High-Loading Ni Catalysts Supported on SiO₂-TiO₂ Binary Oxides

A series of SiO₂-TiO₂ binary oxides supported high loading Ni catalysts were prepared using the co-precipitation method and tested in guaiacol hydrodeoxygenation (HDO). The catalysts were characterized using N₂ adsorption-desorption, XRD, TEM, FT-IR, XPS, H₂-TPD, and NH₃-TPD. The formation of Si-O-Ti bond in the SiO₂-TiO₂ binary oxides was verified by XPS, which can increase the total amount of acidic sites and enhance the interaction between metal Ni and TiO₂. The oxygen defect sites of TiO₂ were formed near the perimeter of the metal-support interface, leading to generation of Ni^δ--O_V-Ti³⁺ interface sites, which play the role of active centers to catalyze guaiacol HDO. These positive factors promoted HDO activity over Ni catalysts supported on binary oxides, compared to Ni loaded on single oxide supports. The selectivity of products indicates relatively high temperature and low H₂ pressure are beneficial for producing oxygen-free aromatics in HDO of guaiacol.