The increasing demand for sustainable chemical processes has fostered the development of advanced catalytic systems for biomass valorization. In this work, a series of mono-, bi-, and trimetallic oxides (FeO, FeCuO, FeZnO, and FeCuZnO) were successfully synthesized using MIL-101-based MOFs as sacrificial templates. The obtained materials were thoroughly characterized by N₂ adsorption–desorption, XRD, FTIR, and TEM/STEM-EDX to investigate their structural, morphological, and textural properties. Their catalytic performance was evaluated in the selective oxidation of benzyl alcohol, a lignin-derived platform molecule, into benzaldehyde under microwave irradiation as a sustainable heating strategy. The results demonstrate that MOF-derived oxides exhibit superior activity compared to their parent MOFs, highlighting the beneficial effect of thermal treatment on the exposure of active sites. Among the catalysts, heterometallic oxides showed enhanced performance due to synergistic effects between metals. In particular, FeZnO reached a maximum yield of 62.1% towards benzaldehyde at 150 °C and 30 min, outperforming the monometallic oxide. Recycling tests revealed that FeZnO retained higher overall performance than FeCuO, which suffered from progressive copper leaching. These findings confirm the potential of MOF-derived multimetallic oxides as efficient and reusable heterogeneous catalysts for selective biomass-derived alcohol oxidation. The combination of microwave-assisted processes and the tuneable nature of MOF-derived oxides provides a promising pathway for designing sustainable catalytic systems with industrial relevance.

Several mixed oxides composed of Fe₃O₄, ZrO₂, and Al₂O₃ with different molar ratios were synthesized through a direct and simple mechanochemical approach. Subsequently, their physicochemical properties were investigated using a wide range of techniques, including TEM (transmission electron microscopy), XPS (X-ray photoelectron spectroscopy), XRD (X-ray diffraction), and N₂ adsorption/desorption, among others. These materials showed high surface areas and increased acidity compared to their respective counterparts. The catalytic activity of the synthesized materials was evaluated in the conversion of methyl levulinate (MEL) to γ-valerolactone (GVL) under microwave irradiation conditions, employing different alcohols as H-donor solvents (ethanol, 2-propanol, and 2-butanol). Due to their improved physicochemical properties originating from the ball-milling method, the as-synthesized materials (ZrFeOx 1:1, AlZrFeOx (5), and AlZrFeOx (10)) exhibited conversion rates of up to 99%, with complete selectivity for GVL after a relatively short reaction time of 30 min.