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/NiAl 2 O 4 @mSiO 2 catalyst by coating 4 nm mesoporous silica (mSiO 2 ) on Ni/NiAl 2 O 4 via soft templating, achieving synergistic optimization of activity and stability. At 250 °C and 3 MPa H 2, Ni/NiAl 2 O 4 @mSiO 2 matched the activity of Ni/NiAl 2 O 4, while its deactivation rate after 4 cycles (7.5%) was much lower than that of Ni/NiAl 2 O 4 (40%). It also exhibited broad applicability to eight fatty acids, delivering >96% alkane yield under optimized conditions. Characterization confirmed that the mSiO 2 layer preserved reactant diffusion/activation while enhancing mass transfer for stearic acid and preventing Ni/NiAl 2 O 4 sintering/metal leaching. This work provides critical insights for designing efficient catalysts in low-grade oil valorization.