A family of NiO‐MgO samples with Ni/Mg molar ratio between 0.10 and 0.30 are synthesized by co‐precipitation and subsequent calcination. The characterization of the samples show the formation of a solid solution with a periclase structure in such a way that the Ni²⁺species are poorly reducible. After the reduction of the NiO‐MgO samples at 500 °C, the catalysts are tested in the furfural (FUR) hydrogenation to obtain valuable products in a one‐pot reaction. The catalysts are highly selective toward tetrahydrofurfuryl alcohol (THFA) with a yield above 50% in most cases as well as 1,2‐pentanediol (1,2‐PeD) and 1,5‐pentanediol (1,5‐PeD) with maximum yield of 22 and 23% after 22 h of reaction at 170 °C and 4 MPa of H₂, respectively. The present work also suggests the presence of two routes in the furfuryl hydrogenation. The first one is associated with the reduction of furfural to furfuryl alcohol (FOL) and the hydrogenation of the ring yielding THFA. In the second route, once FOL is formed, the furanic ring is open to form 1,2‐PeD and 1,5PeD.

Nb-based catalysts supported on porous silica with different textural properties have been synthesized, characterized, and tested in the one-pot reaction of furfural to obtain valuable chemicals. The catalytic results reveal that the presence of fluoride in the synthesis, which limits the growing of the porous silica, limits diffusional problems of the porous silica, obtaining higher conversion values at shorter reaction times. On the other hand, the incorporation of NbO_x species in the porous silica provides Lewis acid sites and a small proportion of Brönsted acid sites, in such a way that the main products are alkyl furfuryl ethers, which can be used as fuel additives.

In this work, a new methodology for dispersing metal particles supported in clay has been described. For this purpose, a sepiolite has been modified by a microwave-assisted treatment to increase the surface area and pore volume due to the progressive leaching of the Mg²⁺-species located in the octahedral sheet. These materials have been used as support to incorporate Cu species on the surface by a precipitation-deposition process from the thermal decomposition of urea at 95 °C. Once calcined and reduced, the Cu-based catalysts showed a Cu⁰-particle size lower than 5 nm in the case of catalysts whose support is a sepiolite subjected to acid treatment. On the other hand, when raw sepiolite is used as a support, the Cu⁰-crystal size is much larger (15–20 nm). This difference in Cu⁰-crystal size showed a variable catalytic behavior for the hydrogenation reaction of furfural in gas-phase. Catalysts with larger particle size promote the hydrogenation reaction, obtaining a yield towards furfuryl alcohol close to 60% after 5 h at 190 °C. In contrast, catalysts with smaller particle size promote the hydrogenation reaction and subsequently the hydrogenolysis reaction, obtaining methylfuran as a product with a yield of 58% after 1 h of reaction at 190 °C; however, the sites where hydrogenolysis are involved are more prone to be deactivated.

This study presents a comprehensive characterization of monometallic (Co or Cu) and bimetallic (Co-Cu) catalysts supported on cerium oxide (CeO₂). XRD and TEM analyses revealed that crystallinity decreases after reduction and that metal dispersion is highly dependent on composition, with cobalt exhibiting greater dispersion than copper. The results confirmed a strong interaction between the metals and CeO₂, which alters the ceria structure and facilitates the reduction of the metal oxides. H₂-TPR and XPS data indicated that monometallic and the bimetallic 15Cu15Co catalysts achieved nearly complete reduction, whereas other bimetallic catalysts did not. Furthermore, CO chemisorption and H₂-TPD demonstrated that the hydrogen activation capacity correlates with the degree of catalyst reduction. Notably, bimetallic catalysts did not show enhanced hydrogen activation compared to their monometallic counterparts. This suggests that the dispersion and metal–support interaction are more critical factors for catalytic activity in this system than the formation of metal alloys. Although the furfural conversion was complete, the selectivity depended greatly on the catalyst composition. The 30Co_R catalyst was most selective for 1,5-pentanediol (38.4%), the 30Cu_R catalyst for 1,2-pentanediol (22.1%), and the bimetallic catalysts for THFA. Reutilising the 30Co_R catalyst after five catalytic cycles resulted in a gradual reduction in the selectivity of 1,5-pentanediol.

In this work, two families of catalysts based on mixed metal oxides derived from MgAl hydrotalcites were synthesized with a Mg/Al molar ratio of 3. On the one hand, in the first family, the fluoride anion was incorporated in the interlayer space by using ammonium fluoride, exploiting the “memory effect” characteristic of hydrotalcites. In the second family, fluoride anions substituted oxides in the layer, incorporating directly them during the precipitation of hydroxides, by using cryolite as a precursor for both fluorine and aluminium. The hydrotalcites were transformed into mixed metal oxides by thermal treatment and tested in the glycerol etherification reaction at 230 ºC, in a batch reactor at atmospheric pressure. The hydrotalcites and the corresponding mixed metal oxides were characterized by different experimental techniques, such as X-ray diffraction (XRD), elemental analysis (CNH), N2 sorption at -196 ºC, thermogravimetric analysis (ATD-TG), X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption of CO2 and NH3 (CO2-TPD and NH3-DTP) and solid state nuclear magnetic resonace (ssNMR) of 19F. It was found that the mixed metal oxides prepared from hydrotalcites, where fluorine was incorporated in the synthesis step using cryolite, achieved the maximum conversion values and complete selectivity towards diglycerol. Diglycerols were the unique detected products and, in some cases, the formation of triglycerols was also detected.