This study addresses environmental concerns associated with glyphosate contamination by developing sustainable iron-modified mesoporous catalysts. Key synthesis parameters such as the iron content (Si/Fe) incorporated in the synthesis gel, the nature and proportion of pore-forming agents and the hydrothermal treatment temperature were studied in depth. The materials were characterized by different techniques such as: XRD, Nitrogen Physisorption, TEM, UV-Vis DR and FTIR of Adsorbed Pyridine. The solids synthesized using glyceril monostearate (GM) or glycerol (G) as renewable porogens were catalytically evaluated for glyphosate degradation under mild conditions (ambient temperature and atmospheric pressure). The best catalytic performance (80% of glyphosate degradation with 100% selectivity for the fragmentation into short-chain ions without aminomethylphosphonic acid, AMPA, formation) was found for the solid prepared by direct incorporation with Si/Fe =10 M ratio, GM as porogen (Si/GM = 5 M ratio) and 85 degrees C of hydrothermal treatment for 3 days. The acidity of catalyst played a crucial role in the activity and selectivity toward the desired products. While strongly acid solids (Fe-M(10)-Si/GM = 5-85 and Fe-M(10)-Si/G = 1/5-85) lead to greater fragmentation of herbicide, those with lower acidity can give rise to the formation of the stable and toxic metabolite AMPA as a degradation product. Thus, the findings of this research open new avenues for developing sustainable and efficient catalysts for the organic pollutant degradation in aqueous environments.

Se sintetizaron exitosamente sólidos silíceos mesoporosos a través de metodologías innovadoras y sostenibles empleando precursores renovables y rutas de síntesis más amigables para el medio ambiente (método sol-gel). Los materiales de partida se obtuvieron mediante síntesis hidrotérmica, utilizando una fuente de silicio extraída de la cáscara de arroz y monoestearato de glicerilo como agente porógeno. Estos materiales nanoestructurados se prepararon con diferentes contenidos de Al mediante síntesis por incorporación directa (Si/Al= 10, 30, 60 y 100) y se caracterizaron por adsorción de N2, SEM-EDS, TEM, RMN, IR-TF y adsorción de piridina acoplada a espectroscopia IR-TF. Así, la mayor incorporación de aluminio en la estructura del material se logró a partir de una relación molar inicial de Si/Al= 10, tratamiento hidrotérmico de tres días y una hora de calcinación a 550 °C. Esta característica condujo a una elevada acidez en los sólidos diseñados, la cual los convierte en atractivos catalizadores para ser aplicados en reacciones industriales de interés impulsadas por sitios ácidos.

La industria de la Química Fina enfrenta el desafío de reducir su impacto ambiental sin comprometer la eficiencia de sus procesos. Así, la biotecnología ofrece una alternativa viable mediante el uso de reactivos ecoamigables y condiciones menos severas de operación que mejorarían el proceso tradicional. Este trabajo propone una ruta sostenible para la obtención de un soporte mesoporoso renovable derivado de biomasa, basado en la inmovilización enzimática sobre el mismo, combinando la selectividad de la proteína con la estabilidad del soporte. Para caracterizar la mesoporosidad del material se emplearon isotermas de adsorción de N2 y TEM. Además, mediante Espectroscopía IR-TF se evaluó la inmovilización enzimática, determinándose que con 96 h de inmovilización y 400 mglipasa/gsoporte se obtendría el mayor contenido de enzima soportada. El biocatalizador resultante fue evaluado en la transesterificación entre acetato de vinilo y alcohol isoamílico, produciendo acetato de isoamilo a 40 °C y presión atmosférica. Se alcanzó un rendimiento del 65 % mol a éster y una conversión del 86 % mol a 20 h de reacción. Estos resultados evidenciaron el potencial del biocatalizador para la síntesis de ésteres saborizantes y aromatizantes, ofreciendo una alternativa más sustentable en comparación con los métodos industriales convencionales.

Obtaining flavorings industrially requires extreme conditions such as high temperatures and pressures, operation of toxic solvents, and use of acids as catalysts. Given these limitations, more eco-friendly alternatives like enzymatic catalysts are being investigated. However, the enzymes stability in organic reagents and reuse are the main drawbacks; therefore, the use of immobilization techniques on novel inorganic supports would allow combining the enzymatic selectivity and the properties of these matrices to increase their catalytic performance. In the present work, the transesterification reaction of vinyl acetate with isoamyl alcohol to produce isoamyl acetate was conducted at 40 degrees C and atmospheric pressure using a mesoporous biocatalyst synthesized from a biomass-derived molding agent. The synthesized materials were characterized by N2 adsorption and desorption isotherm, Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and Infrared Spectroscopy (FT-IR). For the biocatalyst synthesis, the enzyme-support contact times and the enzyme loading were evaluated. The best catalytic performance was obtained with a material prepared with 96 h of immobilization and with a theoretical loading of 400 mglipase/gsupport. High vinyl acetate conversion (86 %) and isoamyl acetate yields (62 %) were achieved at 40 degrees C after 20 h of reaction. The results suggest that the lipases immobilization on renewable mesoporous silica offers a promising alternative route for the sustainable fragrances production under mild operating conditions.

Innovative and sustainable mesoporous siliceous materials have been successfully synthesized from renewable precursors and employing environmentally friendly methodologies (sol–gel method). These materials were prepared by hydrothermal synthesis using an economical and commercially available porogen, glyceryl monostearate, and a source of silica extracted from rice husk, which is an underutilized agro‐waste. Al‐mesoporous‐type nanostructured catalysts with different Al contents were prepared by direct synthesis (Si/Al = 10, 30, 60, and 100) and characterized by N 2 adsorption, SEM‐EDS, TEM, NMR, XPS, FT‐IR, and adsorption of pyridine coupled to FT‐IR spectroscopy. Thus, it was found that the highest incorporation of aluminum into the red was achieved from a Si/Al initial molar ratio of 10, a hydrothermal treatment of 3 days at 85 °C and 1 h of calcination at 550 °C. This feature leads to a high acidity for these materials, which makes them very attractive for their application in acid‐driven industrial reactions of interest. Thus, owing to the excellent physical and chemical properties of these materials, employing renewable sources is possible in the design of materials with catalytic applications, thought a useful, simple, and economical method.

TiO2 nanoparticles codoped with iron and carbon were tested in a photocatalytic processes using visible radiation to degrade Acid Orange 7 and Paracetamol from aqueous solutions. In our previous reports, the mesoporosity and crystallinity of the samples were analyzed along with the calcination temperature effect on the development of the active carbon species in titania matrix.In this work, it was possible to verify the efficiency of a synergistic effect between iron and carbon when a calcination at intermediate temperature (150 ºC) was applied, favoring dopants localization in key sites of the titania structure which improves the response under visible light. Such accomplishments could be also confirmed through photoluminescence spectra analysis. Thus, the optimized solid showed an enhanced photocatalytic performance, reaching, at only one hour of reaction, a complete degradation of both dye and drug while some of their intermediate species were reduced according to the degree of mineralization (around 80%), and biodegradability achieved. Therefore, the proposed photocatalytic system presents a unique potential as a previous treatment to a biological remediation process.

By using nanotechnology and the versatility in the micro-mesoporous solids synthesis, it was possible to design and synthesize catalysts with custom-controlled acidity. Aluminum or boron modified MCM-41 type nanocatalysts (Si/metal = 20) were synthesized by "conventional way" showed a very weak and moderate Bronsted acidity, respectively, caused by the formation of nest silanols due the incorporation of the heteroatom. Aluminosilicates were also synthesized by "zeolitic precursors assembly way" and the presence of these zeolitic domains caused a greater acidic strength. Thus, this development of catalysts with active sites within range of acid strength allows manage the synthesis of different industrial interest compounds.

Iron modified mesoporous silica structures were achieved from biomass-derived renewable molding agents (glyceryl monostearate and glycerol) and can become potential substitutes for conventional mesoporous catalysts synthesized from petrochemical-derived precursors. These materials were prepared by different methods (wet impregnation with iron contents of 2.5, 5, 10 and 20% w/w and direct incorporation using a molar ratio Si/Fe = 20) and characterized by XRD, N2 adsorption and desorption isotherms, UVvis-DR and ICP. By using these solid as heterogeneous catalysts in the wet oxidation reaction of the herbicide glyphosate with air under extremely mild reaction conditions (atmospheric pressure and room temperature), herbicide degradation/fragmentation levels of around 70% were achieved. The methodology employed for the synthesis played a key role in the development of the structure and dispersion of Fe species as well as in the stability of the catalytic system. In this way, an advanced technology with low environmental impact for the treatment of a pollutant of great concern at the global level was developed, which adds sustainability to the chemical industry from the use of residual glycerol and/or glyceryl monostearate in the catalyst synthesis.

En la actualidad el desafío en el desarrollo de procesos para la industria química debe tender a maximizar la eficiencia global integrando parámetros ambientales, energéticos y económicos que aporten sostenibilidad. En este contexto resulta imperativo el estudio de materiales y la implementación de sistemas catalíticos con propiedades avanzadas capaces de satisfacer las actuales demandas. La flexibilidad en el diseño de sólidos mesoporosos permite abordar estos desafíos no sólo a partir de su modificación química con funciones activas específicas sino también a partir de la exploración en el empleo de precursores renovables y metodologías de síntesis más limpias y sencillas.Se propone así el diseño, síntesis y caracterización de nuevos nanomateriales mesoporosos, a partir de precursores renovables, modificados con metales a través de metodologías ambientalmente más amigables para ser aplicados como catalizadores bifuncionales en la reacción de hidrogenólisis de glicerol para obtener bioglicoles.

En este plan de trabajo se diseñarán, sintetizarán y caracterizarán sílicas mesoporosas nanoestructuradas a partir de agentes moldeantes renovables (monoestearato de glicerilo y glicerol) para desarrollar catalizadores heterogéneos, a fin de evaluarlos en reacciones de esterificación de relevancia en el campo de la química fina. Estos materiales se modificarán mediante el método de impregnación húmeda, con contenido de Ca 2,5 % p/p. Los catalizadores serán caracterizados por isotermas de adsorción y desorción de N2, Área superficial por método Brunauer–Emmett–Teller, Difracción de Rayos X y Espectroscopía Infrarrojo. De esta manera se pretende aportar sustentabilidad a la industria química, a partir del empleo de glicerol residual y/o monoestearato de glicerilo para la síntesis de los soportes catalíticos mesoporosos y de una vía enzimática de esterificación que permite condiciones de reacción suaves y eco-compatibles.

Nanostructured solids doped with various iron contents (1, 2.5, 5 and 10 wt%) were developed as efficient catalysts to degrade glyphosate aqueous solutions under extremely mild reaction conditions, atmospheric pressure and room temperature. These materials were characterized by XRD, TEM, N2 physisorption, UVvis-DR and XPS. Regular mesoporous structures typical of SBA-15 solids were obtained and the Fe speciation could be tuned by adjusting the metal nominal loading. The catalysts were evaluated in the glyphosate degradation fragmentation reaction by catalytic wet oxidation with air, achieving herbicide degradation levels of the order of 80%. A reaction way based on the formation of a highly reactive oxo-iron (V) intermediary from Fe-glyphosate complex was proposed. In this manner, an interesting technology with lower environmental impact and greater sustainability for the remediation of water polluted with glyphosate is presented.

SBA type nano-structured catalysts were prepared modified with iron and cobalt. The materials were characterized by XRD, N2 adsorption; TEM, ICP–OES, UV–Vis DRS and FTIR. These solids were evaluated in the glyphosate degradation reaction through catalytic wet air oxidation at atmospheric pressure and room temperature. The reaction products were analyzed by ionic chromatography and they included: acetate, nitrate, nitrite and phosphate ions. The catalyst stability and possibility of recycling were also study. It was found that the Fe and Co ions can form complexes with glyphosate, although only the Fe-SBA(20) catalyst led to the oxidative fragmentation of the herbicide. The Co-SBA(20) material acts as herbicide adsorbent but was not active to achieve its degradation. It is proposed that, the catalyst modified with iron can form a Fe-glyphosate complex which was observed by infrared spectroscopy. This complex was capable to active O2 from an air flow, generating oxoiron intermediates that promote the degradation of the herbicide (into short chain ions, less toxic and more biodegradable) under room reaction conditions.

Pure siliceous and aluminosilicate mesoporous molecular sieves of MCM-41 type have been used as support for nickel incorporation (2.5 wt%) by wet impregnation method. The hydrogen adsorption capacities at 77 K of these materials have been studied. Various techniques such as X-ray diffraction, N2 adsorption–desorption, X-ray photoelectron spectroscopy, Temperature-Programmed Reduction, UV–Vis diffuse reflectance spectroscopy and adsorption of pyridine coupled to infrared spectroscopy were employed to characterize the materials. In addition, Density Functional Theory calculations were used in order to interpret the results of hydrogen adsorption. The results obtained show that isolated metallic species are capable to promote hydrogen favorable sites. Isolated mononuclear Ni2+ species on the surface strengthen the interaction with the H2, enhancing the hydrogen adsorption capacity.

B-MCM-41 type nano-structured materials were prepared by direct hydrothermal synthesis. The time of hydrothermal treatment, the Si/B initial molar ratio and the nature of the hydroxide source in the synthesis process were analyzed. All the materials were characterized by XRD, N2 adsorption, TEM, SEM, ICP-OES, FT-IR and adsorption of pyridine coupled to FT-IR spectroscopy. The role of hydroxide source is essential to achieve the incorporation of boron in the mesoporous structure. The relationship between the Boron content in the synthesis gel, the degree of introduction of tetra-coordinated B into the framework, the formation of nest silanols and the relative density of the acidic sites have been discussed. We could corroborate that hydroxyl groups present in silanol nests are the direct responsible of the moderate Brønsted acidity of our materials. The enhancement in the density of acidic nest silanols was reached by increasing the B content in the mesoporous structure. Finally, the use of NH4OH, as hydroxide source, Si/B initial molar ratio of 10 and 20 and a hydrothermal treatment of 6 days resulted the optimum synthesis conditions to obtain the highest framework B incorporation and more abundant moderate Brønsted sites (silanol nests), thus improving the potential catalytic properties of these materials.

The Beckmann rearrangement of Cyclohexanone oxime at 300-380 degrees C and W/F = 20-60 g h/mol over a B-MCM-41 catalyst was studied at atmospheric pressure. The e-Caprolactam (precursor for nylon-6) was the major product on the whole temperature range studied and Cyclohexanone appeared as the main by-product and was generated probably due to the moderate acidity of these materials. The stability and the possibility of recycling of the catalyst were also analyzed. So, the catalyst could be used during 3600 min and then recovered and reused without significant changes in the active species. A reaction pathway was proposed in order to explain the results obtained. Finally, the better catalytic performance was observed at 320 degrees C and W/F = 40 g h/mol. Such conditions allowed us to achieve a Cyclohexanone oxime conversion of 54% with an e-Caprolactam selectivity of around 83%. Thus, under this mild reaction condition it could be achieved a high yield to e-Caprolactam with a low proportion of Cyclohexanone. This product mixture (e-Caprolactam and Cyclohexanone) may be separated by vacuum distillation; then the Cyclohexanone could be recycled by reaction with hydroxylamine to form again Cyclohexanone oxime (raw material for e-Caprolactam), marketed for the production of adipic acid, as adhesive in sealing PVC objects or as solvent in several industries.

Mesoporous nanomaterials were synthesized from zeolitic precursors and characterized by XRD, adsorption-desorption of N-2, ICP-OES, SEM, TEM, FT-IR and adsorption-desorption of pyridine followed by FT-IR. These materials were catalytically evaluated in the Beckmann reaction, and the reaction products were analyzed by gas chromatography and identified by GC-MS. The activity and the distribution of reaction products were related to the acidic strength of the materials. Thus, it was possible to generate bi-structured catalysts with sites in a certain range of acid strength as potential materials for catalytic processes that require some acidity grade, such as the Beckmann reaction of cyclohexanone oxime for obtaining different products of industrial interest.

The stability and photo Fenton activity of nanoarchitectured silicates modified with Fe by the wet impregnation method were studied as a function of the used solvent, calcination temperature and iron loading. The physicochemical properties were characterized by SAXS, XRD, N2 physisorption, SEM, AA, UV-Vis DR, XPS and TPR. All solids showed long-range structural order typical of SBA-15 with high specific surface, P-V and a narrow distribution of P-D. The proper choice of impregnation solvent allowed tuning the iron speciation in order to obtain catalysts highly stable and efficient for their use in the azo dyes photo-Fenton degradation at pH = 3.5. Calcination temperature does not seem influence on such speciation. Isolated iron cations finely dispersed and strongly anchored on the mesoporous channels, whose formation is promoted by the use of ethanol and the low iron loading, are proposed as active sites for the photo-Fenton process. Likewise, low iron loadings also favor the higher accessibility of these sites to the reactant molecules (AO7 and H2O2). Thus, the highest dye mineralization degree was obtained by an actual iron loading of 1.31% wt. The heterogeneity of the process was confirmed. The more active solid also showed a high stability and reuse capacity, maintaining its performance.

El hidrógeno es un importante vector energético capaz de sustituir el uso de combustibles fósiles en la actualidad. Uno de los principales inconvenientes para la implementación de sistemas que emplean hidrógeno es su almacenamiento. Actualmente, existen investigaciones en curso con el fin de desarrollar materiales para ser empleados en sistemas de almacenamiento, como por ejemplo materiales formadores de hidruros y materiales porosos que almacenan hidrógeno por adsorción. En este trabajo se sintetizaron materiales MCM-41 por síntesis hidrotérmica con relación Si/Ni = 20 y 60 y tiempos de síntesis de 0 a 7 días. Se estudió la influencia del tiempo de síntesis en las propiedades estructurales y texturales de los materiales, y se evaluó la adsorción de hidrógeno y el efecto de incorporar níquel en su estructura para mejorar el almacenamiento. Los materiales fueron caracterizados mediante adsorción-desorción de N2 a 77 K, difracción de rayos X, microscopía electrónica de transmisión y espectroscopia ultravioleta visible con reflectancia difusa.

Se prepararon materiales mesoporosos del tipo B-MCM-41. Se investigó la influencia de la variación del tiempo de tratamiento hidrotérmico, la fuente de hidróxido, el contenido de B, el grado de incorporación del B en la estructura y el carácter ácido del material obtenido. Se confirmó que la acidez de las muestras se debe a los silanoles nido presentes en los defectos estructurales del material sintetizado. Estas especies se generan principalmente por la introducción de B dentro de la estructura y sus propiedades ácidas pueden ser causadas por la presencia del heteroátomo. De esta manera se logró obtener una acidez moderada en los materiales mesoporosos obtenidos, característica muy importante para determinados procesos catalíticos.