Palladium-loaded lanthanum metal organic framework for vanillin hydrodeoxygenation

Metal organic frameworks (MOFs) as effective supports have attracted interest in heterogeneous catalysis, especially for stabilizing metal species on the porous structure. Herein, we synthesize palladium-loaded lanthanum-based MOF (Pd/La-MOF) as an efficient catalyst for vanillin hydrodeoxygenation (HDO). The successful incorporation of Pd nanoparticles onto the La-MOF support was confirmed by a transmission electron microscopy (TEM), while the structural integrity of the La-MOF post-metal loading was verified through X-ray diffraction (XRD) analysis. Thermogravimetric analysis (TGA) demonstrated the thermal stability of the catalyst under reaction conditions. Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and N₂ adsorption–desorption isotherms were employed to evaluate the functional groups, oxidation state, metal support interaction and specific surface area of the material. Catalytic performance of as-prepared Pd/La-MOF catalysts was evaluated for vanillin HDO. Among the different Pd loadings (0.5, 1.0, and 2.0 wt%), the 1.0 wt% Pd/La-MOF exhibited the highest creosol yield of 93 % within 6 h at 160°C under 1.0 MPa H₂ pressure. The reaction mechanism was proposed based on time-profile analysis. Comparative analysis with other Pd-loaded supports demonstrated the superior catalytic efficiency of La-MOF. Additionally, poisoning and leaching studies confirmed the role of acidic sites in creosol formation and the absence of Pd leaching during the reaction. Recyclability tests, along with post-reaction XRD and TEM analyses, confirmed the structural stability of the catalyst and uniform dispersion of Pd nanoparticles after multiple cycles. These results highlight the potential of La-MOF as a thermally stable and effective support for metal-based catalysts, particularly in the Pd-catalyzed HDO reactions.