Crucial role of oxygen vacancies for the efficient hydrodeoxygenation of lignin-based phenolic model compounds with Ni/Ti1−xZrxO2

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Ali, Hadi and Sharma, Neeraj and Kumar, Sahil and Thybaut, Joris W. and Lauwaert, Jeroen and Zhang, Xiaolei and Kansal, Sushil Kumar and Saravanamurugan, Shunmugaval (2025) Crucial role of oxygen vacancies for the efficient hydrodeoxygenation of lignin-based phenolic model compounds with Ni/Ti1−xZrxO2. Catalysis Science and Technology, 15 (12). pp. 3568-3580. ISSN 2044-4761 (https://doi.org/10.1039/d5cy00143a)

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Abstract

Lignin holds enormous potential for biofuel production through thermal and thermochemical processes. However, its high oxygen content in the form of phenolics leads to a low heating value, low stability, and high viscosity. Catalytic hydrodeoxygenation (HDO) with metal-containing catalysts with appropriate oxygen vacancies and active sites represents an efficient route for removing oxygen and producing high-quality liquid hydrocarbons. In this context, our present work focuses on synthesising Ni-doped mixed oxide (Ti1−xZrxO2) supports for the HDO of lignin model compounds (anisole, phenol, cresol). Notably, 3 wt% Ni doped Ti0.50Zr0.50 (Ni/Ti0.50Zr0.50O2) exhibits superior activity and selectivity, achieving a 94% yield of cyclohexane as the primary deoxygenated product, with complete conversion of anisole at 230 °C. In contrast, the mono metal oxide-based support catalysts Ni/ZrO2 and Ni/TiO2 yield 29% and 49% of cyclohexane, respectively. The higher activity and selectivity towards deoxygenated products can be attributed to high oxygen vacancies, Lewis-acid strength and strong metal-support interaction compared to Ni/TiO2 and Ni/ZrO2, as confirmed by the O2-temperature programmed desorption, X-ray photoelectron spectroscopy, NH3-diffuse reflectance infrared Fourier transform spectroscopy and H2-temperature programmed reduction studies. The use of a low percentage (3 wt%) of non-precious metal doped mixed oxide (Ti1−xZrxO2) supports with enhanced oxygen vacancies opens a new window for exploring effective heterogeneous catalysts for the transformation of lignin-derived bio-oil into fuel-grade hydrocarbons.

ORCID iDs

Ali, Hadi, Sharma, Neeraj, Kumar, Sahil, Thybaut, Joris W., Lauwaert, Jeroen, Zhang, Xiaolei ORCID logoORCID: https://orcid.org/0000-0001-9415-3136, Kansal, Sushil Kumar and Saravanamurugan, Shunmugaval;
CORE (COnnecting REpositories)