Catalytic Hydrodeoxygenation of Guaiacol over Palladium Catalyst on Different Titania Supports

Abstract

Pd catalysts supported on TiO 2 with different crystalline phases were prepared with formaldehyde as reducing agent and examined for hydrodeoxygenation (HDO) of guaiacol. Their properties were characterized by N 2 adsorption, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. Compared to the carbon-supported Pd catalysts, TiO 2 -supported Pd catalysts exhibited higher C−O bond scission ability, which may be attributed to the presence of partially reduced titanium species originating from the reduction of Ti 4+ by spillover hydrogen from Pd at 200 °C on the surface of TiO 2 . Guaiacol was hydrogenated on Pd sites to give 2-methoxycyclohexanol, which diffused to partially reduced titanium species and subsequently reacted with hydrogen from Pd to generate cyclohexane. Anatase TiO 2 -supported Pd catalyst gave the highest HDO activity of guaiacol among the Pd catalysts supported on three types of TiO 2 (anatase, rutile, and their mix, P25), suggesting that more partially reduced titanium species are in favor of the HDO reaction because anatase is facile to reduce by H 2 at 200 °C. Higher selectivity of cyclohexane for Pd/TiO 2 reduced at 500 °C than that reduced at 200 °C further confirmed that the enhanced C−O bond scission ability of Pd/TiO 2 is mainly attributed to the partially reduced titanium species on the surface of TiO 2 .

Advances in porous and nanoscale catalysts for viable biomass conversion

“…They also pointed out the crucial effect of TiO 2 phase (anatase, rutile, and their mix, P25) on the performance of Pd catalysts for the vapor phase HDO of guaiacol. 401 Interestingly, 5 wt% Pd catalyst supported on anatase TiO 2 showed higher efficiency in guaiacol HDO to obtain cyclohexane due to the existence of partially reduced titanium species on the surface of anatase TiO 2 that can efficiently cleave the C-O bond in guaiacol. The activity of 5 wt% Ru/TiO 2 catalyst for the vapor phase HDO of guaiacol could be considerably promoted by ZrO 2 addition.…”

Catalytic Upgrading of Biomass Model Compounds: Novel Approaches and Lessons Learnt from Traditional Hydrodeoxygenation – a Review

“…In contrast, Pd/KIT‐6 catalyst was effective for cleave both C=O and C‐OCH 3 and well protects O−H bond, showing 98 % conversion of vanillin and 94 % selectivity of p ‐cresol at 300 °C for 6 h . Lu et al . investigated the hydrogenation of guaiacol over Pd catalyst on different titania and carbon supports.…”

Chemicals from Lignin: A Review of Catalytic Conversion Involving Hydrogen

“…The interaction of the metal M (Pt and Pd) and the Lewis acidic support was proven to be the key for the hydrodeoxygenation of biomass‐derived compounds . For instance, Pd enables hydrogen spillover to partially reduce Ti 4+ , causing a highly hydrodeoxygenation reaction‐sensitive TiO x species . In addition, the phase, pore structure, and acid site numbers of the support accordingly affect the hydrodeoxygenation activity in lignin model compounds conversion .…”