Nanoconfined Mesoporous Silica-Coated Ni Catalyst: Balancing Hydrothermal Stability and Activity for Fatty Acid Hydrodeoxygenation

Low-grade oil hydrodeoxygenation (HDO) is a key route for sustainable fuel production. However, traditional transition metal catalysts suffer from poor activity and hydrothermal deactivation in aqueous acidic environments. Here, we developed a Ni/NiAl₂O₄@mSiO₂ catalyst by coating 4 nm mesoporous silica (mSiO₂) on Ni/NiAl₂O₄ via soft templating, achieving synergistic optimization of activity and stability. At 250 °C and 3 MPa H₂, Ni/NiAl₂O₄@mSiO₂ matched the activity of Ni/NiAl₂O₄, while its deactivation rate after 4 cycles (7.5%) was much lower than that of Ni/NiAl₂O₄ (40%). It also exhibited broad applicability to eight fatty acids, delivering >96% alkane yield under optimized conditions. Characterization confirmed that the mSiO₂ layer preserved reactant diffusion/activation while enhancing mass transfer for stearic acid and preventing Ni/NiAl₂O₄ sintering/metal leaching. This work provides critical insights for designing efficient catalysts in low-grade oil valorization.

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