Several Zr-based materials, including ZrO₂ and Zr-SBA-15, with different silicon/zirconium molar ratios, and ZrO₂/Si-SBA-15 (where SBA-15 stands for Santa Barbara Amorphous material no. 15), have been prepared as hydrogenation catalysts. The materials were characterized using different characterization techniques including X-ray diffraction (XRD), N₂ porosimetry, scanning electron microscopy (SEM/EDX), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) of pyridine adsorption and the pulsed chromatographic method using pyridine and 2,6-dimethylpyridine as probe molecules, mainly, have been employed for the characterization of the structural, textural, and acidic properties of the synthesized materials, respectively. The catalysts have been evaluated in the hydrogenation reaction of methyl levulinate using 2-propanol as hydrogen donor solvent. The reaction conditions were investigated and stablished at 30 bar system pressure with a reaction temperature of 200 °C using around 0.1 g of catalyst and a flow rate of 0.2 mL/min flow rate of a 0.3 M methyl levulinate solution in 2-propanol. All catalysts employed in this work exhibited good catalytic activities under the investigated conditions, with conversion values in the 15–89% range and, especially, selectivity to Υ-valerolactone in the range of 76–100% (after one hour time on stream). The highest methyl levulinate conversion and selectivity was achieved by ZrO₂/Si-SBA-15 which can be explained by the higher dispersion of ZrO₂ particles together with a highest accessibility of the Zr sites as compared with other materials such as Zr-SBA-15, also investigated in this work.

In this study, the co-synthesis of TiO₂ and Cu metallic nanoparticles obtained via one-pot cost-efficient hydrothermal process has been addressed. Different nanocatalysts with Cu contents were characterized by X-ray diffraction, nitrogen porosimetry, scanning electron microscopy, and transmission electron microscopy. The TiO₂ and Cu metallic nanoparticles were synthesized with copper loading up to one (Cu/Ti atomic ratio). Synthesized catalysts exhibited pore sizes in the mesoporous range and high surface areas above 150 m²/g. The particle size for TiO₂ presented a homogeneous distribution of approximately 8 nm, moreover, Cu nanoparticles varied from 12 to >100 nm depending on the metal loading. The nanostructured materials were successfully tested in the conversion of trans-ferulic acid into vanillin under sustainable conditions, achieving the best performance for 0.3 Cu/Ti atomic ratio (70% vanillin yield).

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.