Evaluation of Silica-Supported Metal and Metal Phosphide Nanoparticle Catalysts for the Hydrodeoxygenation of Guaiacol Under Ex Situ Catalytic Fast Pyrolysis Conditions.

A series of metal and metal phosphide catalysts were investigated for the hydrodeoxygenation of guaiacol under ex situ catalytic fast pyrolysis conditions (350 °C, 0.5 MPa, 12 H:1 guaiacol, weight hourly space velocity 5 h). Ligand-capped Ni, Pt, Rh, NiP, and RhP nanoparticles (NPs) were prepared using solution-phase synthesis techniques and dispersed on a silica support. For the metal phosphide NP-catalysts, a synthetic route that relies on the decomposition of a single molecular precursor was employed. The reactivity of the NP-catalysts was compared to a series of reference materials including Ni/SiO and Pt/SiO prepared using incipient wetness (IW) impregnation and a commercial (com) Pt/SiO catalyst. The NP-Ni/SiO catalyst exhibited the largest reduction in the oxygen mol% of the organic phase and outperformed the IW-Ni/SiO material. Although it was less active for guaiacol conversion than NP-Ni/SiO, NP-RhP/SiO demonstrated the largest production of completely deoxygenated products and the highest selectivity to anisole, benzene, and cyclohexane, suggesting that it is a promising catalyst for deoxygenation of aryl-OH bonds. The com-Pt/SiO and IW-Pt/SiO catalyst exhibited the highest normalized rate of guaiacol conversion per m and per gram of active phase, respectively, but did not produce any completely deoxygenated products. [ABSTRACT FROM AUTHOR]