Benzene, toluene, and xylene (BTXs) are the major commodity chemicals serving a wide range of industries with large global economic impact and are currently obtained exclusively from petroleum feedstock. Alternative renewable sources from biomass are raised as a solution to satisfy the pressing needs for a fully sustainable biocommodities industry. For this reason, the chemistry of materials has focused on the synthesis of catalysts that can transform biomass into renewable chemical compounds of interest. In this work, the SBA-15 material was modified with Al to incorporate a specific Br/Le acid sites ratio to make a low-cost tailor-made catalyst for the aromatization reaction of furanic dienes and dienophiles from renewable biomass sources. In order to correlate the catalytic activity of materials with their structure and nature, the solids were characterized by several techniques such as XRD, TEM, ICP, N2 physisorption and FT-IR of adsorbed pyridine. The goal of this work was to maximize the production of p-xylene (PX) by fine-tuning the Al content in SBA-15 and optimizing the reaction conditions. The presence of Lewis (Le) and Br & Oslash;nsted (Br) acid sites in Al-SBA-15 materials with different Al contents was determined and the catalysts were evaluated in the aromatic reaction of 2,5-dimethylfuran with ethylene. The optimal combination of Le sites, to produce the first cycloaddition, and Br sites, for subsequent dehydration, was achieved with the Al(1.28)SBA-15 catalyst. After optimization of main reaction parameters (i. e., pressure, temperature and reagents and catalyst concentrations), a 42 % yield of p-xylene was achieved and maintained even after three consecutive re-cycles of solid catalyst. Finally, the possible extended scope of this catalytic system for producing toluene and trimethylbenzene from the corresponding starting reactants was also evaluated.

Pyrolysis is a promising technology for converting biomass waste into bio-oil, a liquid product that can serve as feedstock for fuels and high-value chemicals. In this study, bio-oil was produced via catalytic pyrolysis of pear pulp waste, a byproduct from juice and jam manufacturing, using a fixed-bed reactor. Initial non-catalytic experiments were conducted under nitrogen and vacuum atmospheres at temperatures ranging from 300 to 450°C for 15 minutes to evaluate the effect of temperature on bio-oil yield. The resulting bio-oils were analyzed by gas chromatography-mass spectrometry (GC-MS) to identify and quantify the chemical compounds. Based on the identified optimal temperature, catalytic pyrolysis experiments were conducted using mesoporous xCe/SBA-15 catalysts with x = 0, 0.1, and 0.2 Ce/Si molar ratios. The catalysts were characterized by XRD, BET surface area analysis, SEM, Raman spectroscopy, and TGA. Among them, the 0.1Ce/SBA-15 catalyst demonstrated the highest activity for furfural production, achieving 15% selectivity and a relative area of 48%. Furfural is a valuable platform chemical used in the synthesis of bioplastics and as a precursor for herbicides, fungicides, and insecticides.

Quaternary Ni-Zn-Mg-Al metallic mixed oxide (MMO) catalysts were synthesized by co-precipitation from layered double hydroxide precursors. The effect of varying Zn content on physicochemical properties and catalytic performance was evaluated. Mg-Al and ternary Ni-Mg-Al and Zn-Mg-Al catalysts were synthetized for comparative purposes. XRD, N2 sorption, MP-AES, CO2-TPD, NH3-TPD, SEM, and EDS characterized the materials’ physicochemical properties. The tested reaction was the transesterification between glycerol and dimethyl carbonate to obtain glycerol carbonate to improve the biodiesel industry. The catalyst containing both Ni and Zn showed the highest glycerol conversion among the evaluated materials. This was related to the increased number and strength of surface basic and acid active sites. Specifically, a high density of strong basic sites and acid ones in the quaternary catalysts was required for the reaction mechanism. The catalyst with 20 at% of Zn (MMO-Ni15Zn20) achieved the highest glycerol carbonate yield (89.6%) under mild reaction conditions and was solvent-free. MMO-Ni15Zn20 catalytic performance was associated with its high total basicity and predominance of strong basic sites and a moderate amount of acid sites. The differences observed between catalytic performances suggest that these results depend on the influence of structural, textural, acid, and basic properties. Reuse tests of the MMO-Ni15Zn20 catalyst showed moderate stability, with a progressive decrease in activity due to the loss of strong basic sites and the formation of agglomerated regions. Nevertheless, MMO-Ni15Zn20 maintained a GC selectivity of 100% in the successive cycles.

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.

Mesoporous iron oxides with tailored structural and magnetic properties were synthesized using the SBA-15 silica template and two different iron precursors: Fe(NO3)(3)& sdot;9H(2)O and Fe(C5H(7)O(2))(3), denoted as FeM-1 and FeM-2, respectively. The synthesis involved a two-step impregnation-calcination process followed by silica removal. Comprehensive characterization was performed using techniques such as nitrogen adsorption-desorption isotherms, TEM, SEM-EDX, XRD, XPS, and Mossbauer spectroscopy, as well as magnetic measurements. The results revealed significant differences in structural and magnetic properties between the two samples. FeM-1 exhibited higher structural order, greater homogeneity, and a single-phase alpha-Fe2O3 composition, whereas FeM-2 showed a bimodal pore size distribution and a dual-phase composition of alpha-Fe2O3 and gamma-Fe2O3. Magnetic characterization indicated enhanced magnetization in FeM-2 due to the ferrimagnetic nature of gamma-Fe2O3, while FeM-1 displayed lower magnetization consistent with the weak ferromagnetic behavior of alpha-Fe2O3. The combination of structural and magnetic analyses demonstrated the critical role of precursor selection in tuning the material properties for potential applications in catalysis and magnetic devices.

This work shows a sustainable methodology for the synthesis of biogenic materials designed for the removal and photodegradation of rhodamine B (RhB), a highly dangerous environmental pollutant that induces reproductive toxicity. The classical synthesis of MCM-41-ordered mesoporous materials was modified using biocompatible rice husk as the silica template. Iron was incorporated and the so-prepared biogenic photocatalysts were characterized by X-ray diffraction, N2 adsorption–desorption isotherms, transmission electron microscopy, diffuse reflectance UV-Vis, surface pH, cyclic voltammetry, and Fourier transform infrared spectral analysis of pyridine adsorption. The photocatalytic performance of the materials was evaluated following the removal by adsorption and the photon-driven degradation of RhB. The adsorption capacity and photocatalytic activity of the biogenic materials were correlated with their properties, including iron content, texture, surface content, and electrochemical properties. The best biogenic material boosted the degradation rates of RhB under UV irradiation up to 4.7 and 2.2 times greater than the direct photolysis and the benchmark semiconductor TiO2-P25. It can be concluded that the use of rice husks for the synthesis of biogenic Fe-modified mesoporous materials is a promising strategy for wastewater treatment applications, particularly in the removal of highly toxic organic dyes.

In this study, the Knoevenagel condensation reaction between vanillin and malononitrile was studied using a heterogeneous catalyst such as MCM-41 with a to nominal nickel loadings of 10.2 wt

This paper presents a novel technology for converting glycerol, a byproduct of the biodiesel industry, into glycerol carbonate, a high-value bioproduct. The effect of calcination temperature on the synthesis of quaternary Cu-Ni-Mg-Al catalysts (MMO-Cu15Ni15-Tz) and their application in the transesterification reaction was investigated. Glycerol conversion remained largely unaffected by calcination temperature; however, selectivity toward glycerol carbonate was influenced. Physicochemical analyses showed increased crystallinity and spinel phase formation with higher calcination temperatures, resulting in lower oxide dispersion and decreased specific surface area. Nonetheless, the preservation of nanolayer morphology and increased pore diameter maintained high conversion rates at elevated temperatures. X-ray photoelectron spectroscopy (XPS) confirmed Cu2+ interactions with the MgAl matrix and the formation of a solid solution. Ultraviolet-visible diffuse reflectance (UV-visible DR) spectroscopy indicated the dominance of octahedrally coordinated Cu2+ and spinel phases at the highest temperature. The MMO-Cu15Ni15-T450 catalyst exhibited the highest concentration of strong basic sites and the lowest concentration of very strong basic sites. Acid-base characterization suggested that very strong basic sites and abundant acid sites promote glycidol formation by glycerol carbonate decarboxylation. Calcination at 450 degrees C was identified as optimal, maximizing glycerol carbonate yield while minimizing byproduct formation. This work supports a biorefinery approach aligned with circular economy principles to reduce the environmental impact of biodiesel production through the use of cost-effective catalysts and efficient processes.

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.

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.

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.

Ti/Z-based (Z = Co, Cu or Mn) SBA-15-type mesoporous photocatalysts were synthesized via wet impregnation. The materials were then characterized to study their morphology by TEM and photochemical properties through electron paramagnetic resonance (EPR) using the 5,5-dimethyl-1-pyrroline N-oxide (DMPO) spin trapping agent in aqueous dimethyl sulfoxide (DMSO) solution at room temperature. Tests with radical scavengers were carried out, which allowed identification of radical recombination processes and assessment of the radical pathways promoted by the materials. Both Cu and Mn were effective in enhancing the photoactivity of Ti-based materials, with Cu intensifying the hydroxyl path and Mn showing affinity towards superoxide. Meanwhile, Co did not increase the photoactivity compared to Ti-modified mesoporous photocatalysts. As the Ti/Mn-modified mesoporous photocatalyst was the most active photocatalytic material, further modifications with different calcination heating rates or Mn loads were tested. Materials synthesized with a heating rate of 8 degrees C min-1 presented the largest photoactivity, reaching a maximum with a 10 wt% nominal Mn load, which also shows high affinity for the superoxide radical reaction pathway. Instead, a 2.5 wt% nominal Mn load with a heating rate of 4 degrees C min-1 enhanced the generation of hydroxyl radicals. Thus, the photogeneration of different radical species from mesoporous photocatalysts can be driven by the nature and load of metals, as well as the heating rate used for the material modification, leading to different active species on the surface.

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.

Bimetallic mesoporous photocatalysts were synthesized via a wet impregnation method using SBA-15 as a support, and characterized by UV–visible diffuse reflectance spectroscopy, low-angle X-ray diffraction and N2 physisorption. Among the tested materials, the Ti/Mn combination exhibited the highest photocatalytic activity in azo dye degradation. To understand this enhanced performance, catalysts with varying Mn loads and calcination ramps were evaluated. Additionally, experiments with radical scavengers (isopropanol, chloroform) and under N2 insufflation were conducted to identify the active radical species. Catalysts prepared with low Mn content and higher calcination ramps showed the greatest activity, which significantly decreased with isopropanol, indicating hydroxyl radicals as the main reactive species. In contrast, samples with higher Mn content and quicker heating displayed reduced activity in the presence of chloroform, suggesting superoxide radical involvement. Spectroscopic analyses (XPS, UV–Vis DRS) revealed that increasing Mn load promotes the formation of Mn2+ over Mn4+ species and lowers the band gap energy. These findings highlight the direct correlation between synthesis parameters, surface composition and optical properties, providing a strategy for fine-tuning the performance of a photocatalyst.

The liquid phase oxidation of trans-2-hexen-1-ol over V-MCM-41 using H2O2 (30 wt.% and 55 wt.%) as oxidant was studied. The V-MCM-41 was synthesized by direct incorporation according to the sol-gel method and characterized by XRD, N2 adsorption-desorption, UV-Vis RD, ICP-OES and FTIR. The high water/oxidant molar ratio in the reaction medium with H2O2 30 wt.% had an adverse effect on the catalytic activity due to the competition between water and oxidant for the active sites of the catalyst. Additionally, a proportional relationship between H2O2 concentration (55 wt.%) and alcohol conversion was observed. However, a decrease in the catalytic activities was found during the recycling tests, indicating the lack of stability of the catalyst under the conditions evaluated. Therefore, 0.1 wt.% of titanium was impregnated on V-MCM-41 and three catalytic cycles were achieved without significant loss of activity. In addition, a reaction mechanism was proposed to explain the oxidation products obtained.

La fotocatálisis heterogénea es un tipo de proceso avanzado de oxidación de gran desarrollo en los últimos años debido a que permite la degradación y mineralización de contaminantes orgánicos mediante la generación de especies radicalarias en la superficie de un semiconductor irradiado, sin requerir otros reactivos. El semiconductor más utilizado es el TiO2 debido a sus propiedades fisicoquímicas y su costo. Sin embargo, éste es de difícil recuperación y requiere irradiación de alta energía para que resulte fotocatalíticamente activo. Para mejorar su desempeño, se ha propuesto la dispersión de TiO2 en la superficie de un material inerte de gran superficie tal como las sílices mesoporosas y la co-modificación con otros metales de transición. En este trabajo se sintetizaron y evaluaron sílices mesoporosas SBA-15 coimpregnadas con Ti y distintas cargas de Mn. Los materiales se caracterizaron ópticamente por DRS y fueron evaluados fotocatalíticamente, siguiendo los resultados por espectroscopía de resonancia paramagnética electrónica (EPR) para poder establecer sus vías radicalarias. Se observó que, a cargas mayores de Mn, el band gap de los materiales desciende y generan más especies reactivas de oxígeno (ROS), principalmente radical superóxido.

En este trabajo se presentan los avances alcanzados en la síntesis y caracterización de nanoestructuras basadas en óxidos de hierro mesoporosos y sus cuplas con Ni y Co, las cuales son diseñadas con el objetivo de conferirles fotoactividad bajo radiación UVA-Vis. Se prevé que en estas condiciones los sólidos den lugar a la generación de radicales oxidantes en medio acuoso capaces de degradar contaminantes orgánicos recalcitrantes. Además, se espera desarrollar propiedades magnéticas adecuadas para facilitar la recuperación y reutilización de los materiales. El método de síntesis seleccionado es el de moldeado duro (hard-templating) que consiste en usar una matriz mesoporosa del tipo de la SBA-15 como molde para la formación de la estructura mesoporosa. De esta manera, luego de eliminar selectivamente la matriz se obtiene un sólido que es una réplica inversa del material utilizado como molde. Las propiedades estructurales y ópticas de los óxidos obtenidos se midieron por medio de sortometría, difracción de rayos X (DRX) y UV-Vis DR. Las propiedades magnéticas se midieron con magnetometría de muestra vibrante (VSM).

A series of ordered mesoporous silicas (MCM-41, SBA-15 and KIT-6) were successfully synthesized and modified with nickel by incipient wetness impregnation method. The supports and catalysts were characterized by N2 adsorption-desorption, XRD, TEM, H2-TPR, UV vis-DR, XPS, ICP and Py FT-IR techniques. All the materials were evaluated in the Knoevenagel condensation reaction between vanillin and malononitrile under microwave irradiation. The catalytic results show the key role that the chosen porous structure plays in the deposition of the active phase and its catalytic behaviour. Thus, by designing a suitable mesoporous catalyst it was possible to carry out such Knoevenagel condensation to obtain 2-(4-hydroxy-3-methoxybenzylidene) malononitrile through a highly efficient and environmentally friendly process, without solvents and reducing reaction times by employing microwave heating.

Desde las últimas dos décadas las sílicas mesoporosas han sido estudiadas debido a su potencial como soportes de varias moléculas y biomoléculas, para aplicaciones en catálisis heterogénea y nanotecnología. En la síntesis de estos materiales se utilizan agentes plantilla que permiten obtener un tamaño de poro variable según los requerimientos y/o aplicaciones necesarias. Uno de los focos de la Ingeniería de los Materiales es explorar metodologías más sostenibles para la obtención de estos sólidos. En este estudio se empleó un moldeante derivado de recursos renovables en la etapa de síntesis de los soportes mesoporosos para luego anclar la lipasa de Pseudomonas fluorescens en estos. De esta manera, el biocatalizador obtenido fue aplicado en reacciones de Química Fina. Específicamente, mediante la transesterificación de alcohol isoamílico con acetato de vinilo se evaluó la producción de acetato de isoamilo, un éster con olor característico a banana empleado como aromatizante y saborizante. Luego de optimizar el tiempo de inmovilización de la enzima y la temperatura de reacción, se logró un rendimiento del 62,5% a las 24h.