Mesoporous Cu(Fe)/SBA-15 catalysts were prepared with distinct metal loadings of ca. 2–10 wt.%. A detailed set of characterizations using X-ray diffraction (XRD), electron paramagnetic resonance (EPR), transmission electron microscopy (TEM), scanning electron microscopy coupled to energy dispersive spectroscopy (SEM-EDS), Mössbauer spectroscopy, X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy was performed to correlate the relationship among structure, electronic properties and catalytic performances. All solids were evaluated in the selective catalytic reduction of NO_x in the presence of CO (CO-SCR). The influence of the metal loadings on the overall activity indicated that introducing high amounts of Fe or Cu on the catalysts was beneficial to form either CuO or α-Fe₂O₃ clusters. Cu_x/SBA-15 series exhibited more efficient activity and poison-tolerant ability during CO-SCR reaction, in contrast to Fe_x/SBA-15. In spite of the Fe species introduced on SBA-15 having structural features similar to those of Cu ones, low interactions among Fe nanoparticles, silica and clusters impeded the high performances of Fe₁₀/SBA-15. XPS revealed the Fe species in a more oxidized state, indicating the stability of the solid after the catalytic tests, in agreement with EPR and Raman spectroscopy. Cu₈/SBA-15 worked better, being recyclable due to the interaction of the Cu²⁺ ions with SBA-15, avoiding the deactivation of the catalyst.

The effects of the metal incorporation into hydroxyapatites on the deactivation behavior of the solids were examined in the esterification of glycerol (EG) reaction. The introduction of Cu, Co, or Ni ions by ion exchange in calcium-deficient hydroxyapatites resulted in active catalysts for the EG reaction. The metal contents were varied from 2.0 to 17.0%, providing better performances at rather high metal contents. Part of metal species existed in the hydroxyapatite lattice structure and also as isolated Cu²⁺, Ni²⁺, and Co²⁺ entities on the surface, as shown by XPS and EPR. The effects of the reaction temperature, reaction time, and glycerol to acetic acid molar ratios were deeply investigated. The spent solids used in this study were characterized by XRD, FTIR, SEM-EDS, chemical analyses, EPR, and XPS. The Cu²⁺–OH acid pairs could promote a superior catalytic performance of Cu-containing hydroxyapatites due to the resistance of these solids against leaching of the active species, which is even better than those of Co and Ni-containing counterparts with high metal contents. Cu into hydroxyapatite had a good reusability and long-term utilization for five consecutive cycles of 24 h under a glycerol to acetic acid molar ratio of 0.25 at 80 °C, and longer reaction times provide triacetin formation. This was due to the fact that Cu was stabilized by interacting with Ca, PO₄, and OH sites into the hydroxyapatite lattice, being highly active for the EG reaction. The results also revealed that isolated Cu²⁺ sites played an important role in enhancing the glycerol conversion, intrinsically due to the Cu-containing hydroxyapatites ability to avoid strong adsorption of glycerol oligomers on the catalytic sites.

A facile strategy for the design of porous supports was obtained by modifying the sol-gel method followed by the wet impregnation technique. In this respect, herein, the acidity of the γ-Al₂O₃ phase was modulated by adding basic MgO, La₂O₃ or ZnO promoters to form binary supported catalysts. The Ni and Co dispersion on the supports associated with their tunable acidity and morphologies resulted in highly porous supported alumina-based catalysts. The physicochemical properties of the solids were comprehensively investigated by XRD, textural properties, Raman and FTIR spectroscopy, SEM-EDS, TEM, EPR and XPS analyses. The catalytic performances in the esterification of glycerol in the presence of acetic acid (EG) for the acetins production were evaluated. The highly dispersed NiO and Co₃O₄ active species on binary porous supports produced synergistic effects appearing to be the reason for the activity of the solids in the EG reaction. Under the optimized reaction conditions, NiCo/MgO-Al₂O₃ was found to be a robust solid with superior catalytic performance and improved stability in four reaction cycles with 65.0% of glycerol conversion with an exclusive selectivity of 53% for triacetin. The presence of Co²⁺/Co³⁺ and Ni²⁺ strongly interacting with the spinel γ-Al₂O₃ and MgAl₂O₄ phases, the latter having a large number of lattice oxygen species, was considered another active component besides those of Ni and Co in the esterification of glycerol.

A series of nanospherical-shaped silicates containing heteroatoms (Al, Zr or Ti) were successfully synthesized using tetraethylorthosilicate (TEOS) or silica colloids as a silicon source. These metallosilicate nanospheres were used as silicon nutrients to obtain silicalite zeolites with micro-mesoporosity and improved textural properties. The results demonstrated that TEOS acted as a suitable silicon source to produce amorphous silicates and a spherical-type zeolite architecture with Zr and Ti heteroatoms included in their framework, with preferable particle size and crystallinity. The surface functionality of the mesostructured nanospheres and zeolite silicates provide active centers for the esterification of glycerol with acetic acid (EG) reaction. The dispersion of Cu entities on the surface of the zeolites achieved high glycerol conversions selectively producing triacetin in comparison with Fe counterparts.

A series of nanospherical shaped silicates containing heteroatoms (Al, Zr or Ti) were successfully synthesized using TEOS or silica colloids as silicon source. These metallosilicate nanospheres were used as silicon nutrients to obtain silicalite zeolites having micro-mesoporosity with improved textural properties. The results demonstrated that TEOS acted as a suitable silicon source to produce amorphous silicates and a spherical-type hierarchical zeolite architecture with Zr and Ti heteroatoms included in their framework, with preferable particle size and crystallinity. The surface functionality of the mesostructured nanospheres and zeolite silicates provide active centers for the esterification of glycerol with acetic acid (EG) reaction. Besides, the dispersion of Cu or Fe entities on the surface of the nanospherical silicates and zeolites provided good catalytic performances in the esterification of glycerol to valuable acetins.