Gabriela Díaz

γ‐Valerolactone (GVL) is a derivative of lignocellulosic biomass, which has been identified as a key sustainable platform molecule for the production of renewable fuels and fine chemicals. The presence of M ^δ+ species resulting from the metal–support interactions can serve as a descriptor of the activity and selectivity in this hydrogenation reaction. In this work, Au, Rh, and Ir nanoparticles supported on TiO ₂ were prepared and studied in levulinic acid hydrogenation to evaluate how the strong metal–support interaction (SMSI) effect alters their catalytic performance. The catalysts were characterized adequately by AA, HRTEM, TPR, XPS, and DRIFTS techniques. The catalytic activity was studied under relatively mild thermal conditions (90°C) and conventional hydrogen pressure (50 bar). Among these three catalysts, Ir/TiO ₂ exhibited the most promising catalytic performance for obtaining the GVL compound without involving the formation of the β‐AL intermediate. This behavior can be attributed to a higher proportion of M ^δ+ species, which promote the preferential adsorption of the carbonyl group.

Growing environmental concerns and the persistence of organic pollutants underscore the urgent need for effective wastewater treatment. Among the various strategies developed to address this challenge, photocatalysis has emerged as a promising approach due to its potential for sustainable and efficient degradation of pollutants. In this study, we investigate the simultaneous incorporation of transition metal cations (Cu ² ⁺, Ni ² ⁺, Co ² ⁺, and Fe ³ ⁺) into the crystalline structure of titanate nanotubes (H₂Ti₃O₇, TiNT) via a straightforward ion-exchange method. This modification promotes the formation of a p-n heterostructure between TiNT and the corresponding metal oxides (CuO, NiO, CoO, and Fe₂O₃). Remarkably, metal cation incorporation leads to a substantial reduction in the band gap, from 3.3 eV to 1.5 eV, and induces a new absorption feature associated with the formation of p-n heterojunctions. These modifications effectively extend the light absorption of the materials into the visible region. Furthermore, the formation of the p-n heterojunction increased charge carrier density compared to that obtained in pristine TiNT. The photocatalytic activity of the resulting metal-doped TiNT (M-TiNT) semiconductors was evaluated for the degradation of ibuprofen and indigo carmine under both UV and visible light irradiation. The enhanced photocatalytic performance is attributed to improved light harvesting and increased availability of charge carriers, facilitating the generation of reactive redox species. The importance of the hydroxyl radical as a reactive species was confirmed using a hydroxyl radical scavenger, which led to a significant reduction in photocatalytic activity compared to the control experiment without the scavenger. Notably, Cu–TiNT remained stable after the reuse cycles, retaining 90% of its initial photoactivity. These findings provide valuable insights for the rational design of nanostructured photocatalysts and underscore the potential of metal-doped TiNTs for efficient environmental remediation.

In comparison with fully activated MIL-53(Al)-TDC, MeOH@MIL-53(Al)-TDC shows a 39% higher SO ₂ capture capacity.

Li₂MnO₃is able to selectively trap CO in the presence of H₂at high temperatures, favoring H₂enrichment from syngas flows.

A series of LaNiO₃ materials were synthesized by the EDTA–citrate complexing method, modifying different physicochemical conditions. The LaNiO₃ samples were calcined between 600 and 800 °C and characterized by XRD, SEM, XPS, CO-TPD, TG, DT, and N₂ adsorption. The results evidence that although all the samples presented the same crystal phase, LaNiO₃ as expected, some microstructural and superficial features varied as a function of the calcination temperature. Then, LaNiO₃ samples were tested as catalysts of the CO oxidation process, a reaction never thoroughly analyzed employing this material. The catalytic results showed that LaNiO₃ samples calcined at temperatures of 600 and 700 °C reached complete CO conversions at ~240 °C, while the sample thermally treated at 800 °C only achieved a 100% of CO conversion at temperatures higher than 300 °C. DRIFTS and XRD were used for studying the reaction mechanism and the catalysts’ structural stability, respectively. Finally, the obtained results were compared with different Ni-containing materials used in the same catalytic process, establishing that LaNiO₃ has adequate properties for the CO oxidation process.

The present minireview summarizes recent advances in the application of metal halide perovskite for CO ₂ photoreduction.

Platinum catalysts (1.5 wt. %) supported over CeO2 and γ-Al2O3 were synthesized via wet impregnation using two different Pt precursors: H2PtCl6 and Pt(acac)2. Catalysts were tested in the dry reforming of methane (DRM) reaction at stoichiometric conditions (CH4/CO2 molar ratio of 1) with two approaches: as a function of temperature (400-800 °C) and as a function of time on-stream (800 °C / 24 h). Platinum supported over ceria catalysts showed better catalytic properties, especially in the stability tests, where deactivation was almost negligible. In contrast, alumina-supported catalysts stability was considerably lower due to the increased formation of carbon residues and the significant Pt particle sintering after reaction at 800 °C for 24 h. Through different characterization techniques (TEM, CO chemisorption), a strong Pt-Ceria interaction was evidenced, which helped in preventing Pt particle agglomeration under reaction conditions and promoted active interface sites. Both features are proposed to be responsible for the Pt/CeO2 catalysts better catalytic performance. The effect of the Pt precursor depends on the nature of the support. In ceria, Cl species benefited the generation of oxygen vacancies and surface ceria reducibility; both features are responsible for the Pt/CeO2 anti-coke properties, thus impacting positively in the catalytic performance of the Pt(-cl)/Ce sample. Conversely, in alumina, these Cl species triggered particle sintering and carbon deposition during the DRM reaction, affecting the Pt(-cl)/Al catalytic performance. Resumen. Catalizadores de platino (1.5 % en peso) soportados sobre CeO2 y γ-Al2O3 fueron sintetizados mediante impregnación húmeda utilizando dos diferentes precursores de Pt: H2PtCl6 and Pt(acac)2. Los catalizadores fueron evaluados en la reacción de reformado seco de metano (DRM) en condiciones estequiométricas (razón molar de CH4/CO2 igual a 1) y con dos metodologías: en función de la temperatura de reacción (400-800 °C) y en función del tiempo de reacción (800 °C / 24 h). Los catalizadores de platino soportados sobre ceria mostraron las mejores propiedades catalíticas, especialmente en las pruebas de estabilidad, donde la desactivación fue muy baja. Por el contrario, la estabilidad catalítica de las muestras soportadas en alúmina fue considerablemente menor, debido tanto a la formación de residuos de carbón como al sinterizado de partículas de Pt. Por medio diferentes técnicas de caracterización (TEM, Quimisorción de CO), se evidenció una fuerte interacción Pt-Ceria, la cual ayudó a prevenir la aglomeración de partículas de Pt durante la reacción, además de promover la generación de sitios activos interfaciales. Ambas características se proponen como las responsables de las mejores propiedades catalíticas presentadas por los catalizadores Pt/CeO2. El efecto del precursor del Pt depende de la naturaleza del soporte. En ceria, las especies de cloro beneficiaron la generación de sitios vacantes de oxígeno así como la reducción superficial de la ceria; ambas características son responsables de las propiedades anti-coque en el sistema Pt/CeO2, por lo tanto, estas impactaron positivamente en el desempeño catalítico de la muestra Pt(-cl)/Ce. Por el contrario, en la alúmina, estas especies cloradas aparentemente promovieron el sinterizado de partículas y los depósitos de carbono durante la reacción, lo cual afectó el desempeño catalítico de la muestra Pt(-cl)/Al.