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

Abstract

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 Niδ−–OV–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.

Unravelling local environments in mixed TiO2–SiO2 thin films by XPS and ab initio calculations

“…In other words, chain segments or 'clusters' composed of pure phases are, on average, q 1/ larger than in the random mixture. The transition matrix (7) gives the stationary distributions of O environments (6).…”

“…The mixed TiO 2 -SiO 2 oxides have attracted considerable attention in the area of photocatalysis as it has been shown that they are more active than pure TiO 2 [1][2][3]. The mixed oxides serve as base components for complex nanomaterials with applications in photoluminescence [4], electrochemical sensors [5] or catalytic hydrogenation [6] dehydrogenation [7] and hydrodeoxygenation [8]. There are also multiple possible optical application for those coatings [9], with demonstrated use in waveguides [10,11], laser mirrors [12] and rugate filters [13].…”

Hydrodeoxygenation of benzyl alcohol on transition-metal-containing mixed oxides catalysts derived from layered double hydroxide precursors

“…Some studies used catalysts combining noble and transition metals, such as supported Rh-Co in the HDO of anisole and biodiesel [4] or Ru-Fe in supported ionic liquid phase catalysts in HDO of aromatic substrates containing carbonyl groups [16]. However, noble metals are expensive, and hence their replacement by other transition metals is desired [4,8] and was thoroughly investigated [3,8,10,[17][18][19][20][21][22][23][24]. Another beneficial effect of transition-metal catalysts is that complete hydrogenation of the oxygenated compounds is avoided [3,10].…”

“…High conversions were obtained for all catalysts (80-97 %) with selectivities to HDO up to 97%. Other tested catalysts were molybdenum nitrides [17], Mo2C [22], copper chromite [3], Ni-Fe/SiO2 [19], Ni-Fe/γ-Al2O3 [18], Ni-Mo/γ-Al2O3 [24], NiFe alloys [21], supported Ni catalysts [20,23]. Mixed oxides catalysts containing copper are interesting for HDO reactions due to their high activity in hydrogenolysis and low tendency towards complete hydrogenation of the substrates [3].…”

In Situ Hydrodeoxygenation of Lignin-Derived Phenols With Synergistic Effect Between the Bimetal and Nb2O5 Support

“…Among these nonprecious metal catalysts (Co (Han et al, 2019), Mo (Yang et al, 2019), Ni, etc. ), nickel-based (Qiu et al, 2016;Zhang et al, 2018;Lu et al, 2019;Resende et al, 2019;Li et al, 2020;Shafaghat et al, 2020;Song et al, 2020) catalysts have been extensively studied for the hydrodeoxygenation of different biooil model compounds. Therefore, nonprecious metal catalysts represented by nickel-based catalysts have attracted much attention because of their high hydrogenation activity and low cost.…”