Efficient Hydrodeoxygenation of Lignin-Derived Phenolic Compounds over Bifunctional Catalyst Comprising H4PMo11VO40 Coupled with Ni/C

Abstract

In the catalytic transformation of bio-oil into liquid fuels having alkanes via hydrodeoxygenation (HDO), the acid and metal sites in the catalyst are pivotal for promoting the HDO of lignin-derived phenolic compounds. This study introduces a novel bifunctional catalyst comprising phosphomolybdenum-vanadium heteropolyacids (H₄PMo₁₁VO₄₀) coupled with Ni/C. The HDO reaction of the model compound guaiacol was carried out under reaction conditions of 230 °C, revealing the superior performance of H₄PMo₁₁VO₄₀ with Ni/C catalysts compared to the conventional acids, even at low dosage. The Keggin structure of H₄PMo₁₁VO₄₀ provided a solid catalyst with strong acidic and redox properties, alongside advantages such as ease of synthesis, cost-effectiveness, and tunable acid and redox properties at the molecular level. Characterization of Ni/C and the prepared acid demonstrated favorable pore structure with a mesopore volume of 0.281 cm³/g and an average pore size of 3.404 nm, facilitating uniform distribution and catalytic activity of Ni-metal. Incorporating acid enhances the acidic sites, fostering synergistic interactions between metal and acidic sites within the catalyst, thereby significantly enhancing HDO performance. Guaiacol conversion at 230 °C reached 100 %, with a cyclohexane selectivity of 89.3 %. This study offers a promising avenue for the conversion and upgrading of lignin-derived phenolic compounds.

Keywords: Biomass conversion; Heteropolyacids; Hydrodeoxygenation; Lignin; Phenolic compounds; Supported catalysts.