Search Results (11,083)

In this explorative work, molybdenum trioxide (MoO₃) and representative doped MoO₃ materials, i.e., Cu-doped MoO₃ (2% Cu, “Cu-MoO₃”) and H-doped MoO₃ (H_0.31MoO₃, “H-MoO₃”), have been tested for the first time as photocatalysts in the UV-vis light-driven depolymerization of lignin. The catalysts have been characterized by XRD, TEM, ATR-FTIR, and UV-vis DRS. Under the adopted conditions (UV-vis irradiation, solvent 0.01 M aqueous NaOH, lignin 200 ppm, catalyst 1 g/L, rt, 5 h), photocatalytic depolymerization of wheat-straw lignin (WSL) produced increasing amounts of bio-oil on changing the catalyst from pristine MoO₃ to Cu-MoO₃ and H-MoO₃ (23%, 28% and 30%, respectively). Also, quantification of vanillin and vanillic acid shows a similar increasing trend. These results appear in line with the estimated band gap energies, which decrease in the order: MoO₃ (2.91 eV) > Cu-MoO₃ (2.86 eV) > H-MoO₃ (2.77 eV). H-MoO₃ shows the best catalytic performance, which was then fruitfully explored in the photocatalytic depolymerization of benchmark commercial Kraft lignin (bio-oil yield 32%, vanillin and vanillic acid yields 1.28% and 0.78%, respectively). In view of the results obtained, this work is expected to provide new ideas for the design of heterogeneous photocatalytic system for lignin cleavage. Full article

The synthesis, in particular the industrial production, of pharmaceuticals requires a broad arsenal of synthetic reactions capable of selectively forming specific structural motifs and assembling smaller building blocks into complex molecules. The Chan–Evans–Lam cross-coupling reaction, which forms a bond between a N-nucleophile and an aryl group from a boronic acid, catalysed by copper salts, is a typical example of this synthetic route. Considering the toxicity of copper and the stringent regulatory limits for its residues in final pharmaceutical products, a heterogeneous catalytic approach offers a viable alternative for this transformation. In this work, we present a simply and reproducibly synthesized catalyst based on copper nanoparticles supported on reduced graphene oxide (Cu-rGO), with high efficiency in a model Chan–Lam reaction involving benzimidazole and aniline derivatives with substituted boronic acids. Full article

A series of silica-supported, nitrogen-doped carbon-encapsulated cobalt–nickel alloy catalysts (Co_xNi_y@NC/SiO₂) was successfully synthesized and systematically evaluated for the liquid-phase hydrogenation of 1-nitronaphthalene to 1-naphthylamine. Physicochemical characterization confirmed that the incorporation of nickel promotes the formation of Co–Ni alloys and modulates the electronic structure of the catalysts. The catalytic performance was found to be highly sensitive to the Co/Ni ratio, with Co₂Ni₁@NC/SiO₂ exhibiting the most outstanding activity. Under optimized reaction conditions (90 °C, 0.6 MPa H₂, 5.5 h), both the conversion of 1-nitronaphthalene and the selectivity toward 1-naphthylamine reached approximately 99%. The catalyst also demonstrated excellent stability and recyclability, attributed to the protective nitrogen-doped carbon shell and the synergistic interaction between the Co–Ni alloy and M–N_x active sites. This work provides a new strategy for designing efficient and robust non-noble-metal catalysts for hydrogenation reactions. Full article

Constructed wetlands (CWs) are signified as green, self-sustaining systems for wastewater treatment. To date, their conventional designs struggle with slow kinetics and poor removal of refractory pollutants. This review redefines CWs as photo-reactive engineered systems, integrating near-neutral Fenton and photo-Fenton processes and in-situ oxidant generation to overcome diffusion limits, acid dosing, and sludge formation. By coupling catalytic fillers, solar utilization, and plant–microbe–radical (ROS) synergies, the approach enables intensified pollutant degradation while preserving the low-energy nature of CWs. Bibliometric trends indicate a sharp rise in studies linking CWs with advanced oxidation and renewable energy integration, confirming the emergence of a circular treatment paradigm. A decision framework is proposed that aligns material selection, reactor hydrodynamics, and solar light management with sustainability indicators such as energy efficiency, Fe-leach budget, and ROS-to-photon yield. This synthesis bridges environmental biotechnology with solar-driven catalysis, paving the way for next-generation eco-engineered wetlands capable of operating efficiently beyond the classical Fenton constraints. This work introduces the concept of “Constructed Wetlands Beyond the Fenton Limit”, where CWs are reimagined as photo-reactive circular systems that unify catalytic, biological, and solar processes under near-neutral conditions. It provides the first integrated decision matrix and performance metrics connecting catalyst design, ROS efficiency, and circular sustainability that offers a scalable blueprint for real-world hybrid wetland applications. Full article

Catalytic dry reforming of ethanol offers a sustainable pathway for syngas and hydrogen production through CO₂ utilization, though its efficiency depends heavily on the strategic synthesis of catalysts and the optimization of reaction parameters. This study employs Box–Behnken Design (BBD) and Response Surface Methodology (RSM) to optimize hydrogen yield from CO₂ reforming of ethanol over a Yttrium-promoted Ni-Co/MCM-41 catalyst. The catalyst was synthesized using sequential wet impregnation method and characterized for its physicochemical properties. The catalyst was tested in fixed-bed reactor using experimental data obtained from BBD considering the effects of temperature (550–700 °C), ethanol flowrate (0.5–1 mL/min) and CO₂ flowrate (15–30 mL/min) on the hydrogen yield. The experimental conditions were optimized using RSM quadratic model. The characterization revealed that the ordered mesoporous nature of the MCM-41 is maintained providing a high surface area of 597.75 m²/g for the catalyst. The addition of Yttrium as a promoter facilitates the formation of well crystallized nanoparticles. Maximum hydrogen yield of 85.09% was obtained at 700 °C, 20.393 mL/min and 0.877 mL/min for temperature, CO₂ and ethanol flowrate, respectively. The predicted hydrogen yield obtained is strongly correlated with the actual values as indicated by R² of 0.9570. Full article

The study aims to develop a method for obtaining a high-performance catalyst for the synthesis of liquid hydrocarbons using the Fischer–Tropsch method based on ultradisperse cobalt powders obtained by the electric explosion method. To determine the catalytic activity of the obtained catalyst samples, the main process parameters, like temperature in the catalyst bed, the process pressure, the feedstock space velocity, and the ratio of reagents in the synthesis gas, were varied. It has been established that highly dispersed cobalt powder obtained by the electrical explosion method is a fairly active catalyst for the synthesis of liquid hydrocarbons via the Fischer–Tropsch process. It has been established that the overall CO conversion rate in the temperature range from 230 to 330 °C ranges from 25 to 90%. However, the formation of the main byproduct of the synthesis, carbon dioxide, is not observed below 270 °C. It was determined that for the developed catalyst sample, the optimal temperature range is from 230 to 260 °C, in which the yield of by-products of synthesis and gaseous hydrocarbons is quite low—the selectivity for methane does not exceed 20%, with the proportion of C₅₊ hydrocarbons in the liquid phase at the level of 80%. The CO conversion rate increases proportionally with growing pressure. It has been established that cobalt nanopowder exhibits high catalytic activity in reactions of liquid hydrocarbon formation with low hydrogen content in the initial synthesis gas. This fact allows us to conclude that it has potential for use in processing gases obtained during the pyrolysis of biomass or other non-traditional sources of synthesis gas, characterized by an H₂:CO ratio of 1:1 to 1.25:1. Catalysts obtained from ultradisperse cobalt powders were shown to be resistant to rapid deactivation under synthesis conditions at operating temperatures for 30 h. During long-term testing, CO conversion remained at 23.5% at 230 °C for the entire duration of the experiment. Full article

Direct hydroxylation of benzene to phenol using hydrogen peroxide is a cornerstone of sustainable green chemistry. This paper presents the results of a stability study of an iron-containing mordenite catalyst in the liquid-phase hydroxylation of benzene to phenol with a 30% aqueous hydrogen peroxide solution. The study utilizes a combination of catalytic activity measurements, dynamic light scattering (DLS), and electron paramagnetic resonance (EPR) spectra. The system is initially shown to exhibit high phenol selectivity; however, over time, DLS measurements indicate aggregation of the catalyst particles with an increase in the average particle diameter from 1.8 to 2.6 μm and the formation of byproducts–dihydroxybenzenes. Iron is present predominantly as magnetite nanoparticles (Fe₃O₄) ~10 nm in diameter, stabilized on the outer surface of mordenite, with minor leaching (<10%) due to the formation of iron ion complexes with ascorbic acid as a result of the latter’s interaction with magnetite particles. Using a thermodynamic approach based on the Ulich formalism (first and second approximations), it is shown that the reaction of benzene hydroxylation H₂O₂ in the liquid phase is thermodynamically quite favorable (ΔG° = −(289–292) kJ·mol⁻¹ in the range of 293–343 K, K = 1044–1052). It is shown that ascorbic acid acts as a redox mediator (reducing Fe³⁺ to Fe²⁺) and a regulator of the catalytic medium activity. The stability of the catalytic system is examined in terms of the Lyapunov criterion: it is shown that the total Gibbs free energy (including the surface contribution) can be considered as a Lyapunov functional describing the evolution of the system toward a steady state. Ultrasonic (US) treatment of the catalytic system is shown to redisperse aggregated particles and restore its activity. It is established that the catalytic activity is due to nanosized Fe₃O₄ particles, which react with H₂O₂ to form hydroxyl radicals responsible for the selective hydroxylation of benzene to phenol. Full article

Modulating the electronic structure and surface properties of graphitic carbon nitride (g-C₃N₄) by chemically phosphorus doping is an effective strategy for improving its photocatalytic performance. However, in order to benefit from practical applications, the cost-effectiveness, efficiency, and optimization of the doping level need to be investigated further. Herein, we report a structural doping of P into g-C₃N₄ by in situ polymerization of the mixture of dicyandiamide (DCDA) and phosphorus pentoxide (P₂O₅). As an alternative to previous studies that used complex organic phosphorus precursors or post-treatment strategies, this work proposed a one-pot thermal polycondensation method that is low-cost, scalable, and enables controlled phosphorus substitutions at carbon sites of the g-C₃N₄ heptazine structure. Most of the structural features of g-C₃N₄ were well retained after doping, but the electronic structures and light harvesting capacity had been effectively altered, which provided not only a much better charge separation but also an improvement in photocatalytic activity toward H₂ evolution under irradiation of a simulated sunlight. The optimized sample with P-doping content of 9.35 at.% (0.5PGCN) exhibited an excellent photocatalytic performance toward H₂ evolution, which is over 5 times higher than that of bulk g-C₃N₄. This work demonstrates a facile one-step in situ route for producing high-yield photocatalysts using low-cost commercial precursors, offering practical starting materials for studies in solar cells, polymer batteries, and photocatalytic applications. Full article

The catalytic removal of toluene, a representative aromatic volatile organic compound (VOC), requires efficient and stable catalysts. This study systematically investigated the effect of B-site doping with transition metals (Fe, Cu, and Ni) on the catalytic performance of LaMnO₃ perovskite for toluene oxidation. The LaMn_0.5X_0.5O₃ catalysts were synthesized via a sol–gel method and evaluated. The LaMn_0.5Ni_0.5O₃ catalysts exhibited the optimal catalytic performance, achieving toluene conversion temperatures of 243 °C at 50% conversion (T₅₀) and 296 °C at 90% conversion (T₉₀). Comprehensive characterization revealed that Ni doping effectively refined the catalyst’s microstructure (grain size decreased to 19.21 nm), increased the concentration of surface-active oxygen species (142.7%), elevated the Mn⁴⁺/Mn³⁺ ratio to 0.65, and enhanced lattice oxygen mobility. These modifications collectively contributed to its outstanding catalytic activity. The findings demonstrate that targeted B-site doping, particularly with Ni, is a promising strategy for engineering efficient perovskite catalysts for VOC abatement. Full article

The hydrogenation of the biomass platform compound, ethyl levulinate, for the synthesis of γ-valerolactone represents a highly promising pathway for biomass valorization. Transition metal phosphates are extensively utilized in biomass hydrogenation reactions due to their Brønsted and Lewis acid sites. In this study, we synthesized a series of transition metal (Ni, Co, and NiCo) phosphide catalysts using the liquid phase method. We investigated the effects of metal species and initial Co/Ni molar ratios on catalytic activity in hydrogenation of ethyl levulinate and optimized the reaction conditions. The NiCoP-1.00 sample, prepared with a Co/Ni molar ratio of 1, demonstrated high efficacy in the hydrogenation of ethyl levulinate to γ-valerolactone, achieving excellent selectivity (97.9%) under optimized conditions. Experimental findings indicate that the synergistic interaction between Ni and Co facilitates the hydrogenation of the intermediate ethyl 4-hydroxypentanoate to γ-valerolactone while inhibiting excessive hydrogenation. The catalytic performance of the NiCoP-1.00 catalyst remained stable over five recycling runs. Full article

Pectin-derived oligosaccharides (POS) are emerging as promising functional prebiotics with growing industrial interest. This study reports a synergistic fungal pectinolytic biocatalytic system comprising endopolygalacturonase (EndoPG) and pectin methylesterase (PET11) from Aspergillus aculeatinus BCC 17849 for the controlled depolymerization of pomelo (Citrus maxima) albedo pectin. PET11-mediated demethylation increased substrate accessibility, thereby enhancing EndoPG-catalyzed hydrolysis and resulting in higher POS yields than those obtained with single-enzyme systems. The highest production of short-chain POS, comprising GalA, di-GalA, and tri-GalA (681 mg/g substrate), was achieved at an EndoPG:PET11 dosage ratio of 15:5. The resulting POS fraction significantly promoted the growth of five probiotic strains, including Lactobacilli and Bifidobacteria species, and enhanced probiotic adherence to intestinal epithelial cells. In particular, Lactobacillus acidophilus TBRC 5030 exhibited the highest adhesion level (35.24 ± 6.43%) in the presence of 2.0 mg/mL POS. Overall, this work demonstrated that enzyme-assisted demethylation coupled with targeted endo-hydrolysis enables effective tailoring of POS chain length, providing a promising biocatalytic strategy for pectin valorization into prebiotic ingredients. Full article

Ni-based catalysts have been extensively investigated for lignin hydrogenation; however, they often exhibit limited phenol selectivity and poor catalytic stability. To address these challenges, we introduced Cu as a promoter, resulting in the development of NiCu/ZSM-5 catalysts with significantly enhanced phenol selectivity and durability. Characterization studies revealed that Cu species form an alloy structure with Ni, which effectively suppresses the sintering of Ni nanoparticles during the catalytic process, thereby maintaining consistent performance over multiple reaction cycles. Furthermore, the Cu-Ni alloy demonstrated improved hydrogen activation capability while reducing overall H₂ uptake, leading to a marked increase in phenol selectivity compared to the Cu-free Ni/ZSM-5 catalyst. As a result, the Ni₁Cu₁/ZSM-5 (Ni/Cu molar ratio = 1:1) catalyst achieved a lignin conversion of 69.8% and a phenol selectivity of 84.4%, with negligible performance degradation over 8 cycles. The strategy presented in this work may offer an effective approach for enhancing the performance of industrial catalysts in lignin upgrading processes. Full article

High-density aviation fuels and diesel-range cycloalkanes are in high demand for the transportation sector, but the development of sustainable and high-efficiency synthesis routes from biomass-derived platform chemicals remains a key challenge. High-density aviation fuel and diesel-grade cycloalkanes were successfully synthesized from biomass-derived isophorone and furfural through a continuous process of selective hydrogenation, aldol condensation, and hydrodeoxygenation reaction. (E) 2-(Furan-2-methylene)-3,5,5-trimethylcyclohex-1-one (1A) was obtained by selective hydrogenation of isophorone to obtain 3,3,5-trimethylcyclohexanone (TMCH), which was then subjected to aldol condensation with furfural. The system studied key reaction parameters such as solvent type, temperature, catalyst type, catalyst loading, and reaction time that affect the aldol condensation of TMCH and furfural. The yield of 1A reached 98.69%, under optimized conditions using NaOH as the catalyst at a molar ratio of 3,3,5-trimethylcyclohexanone:furfural = 1:1, NaOH 0.15 g, anhydrous ethanol as the solvent, and a reaction temperature of 313 K for 1 h. A series of nickel-based catalysts supported on porous materials, including SiO₂, CeO₂, Al₂O₃, Hβ, and HZSM-5, were prepared and characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). These catalysts were evaluated for the hydrodeoxygenation of 1A. Among them, the 10% Ni-SiO₂ catalyst exhibited the highest catalytic activity, affording a C₉–C₁₄ cycloalkane yield of 88.32% and a total carbon yield of 99.6%. This work demonstrates a promising and sustainable strategy for producing branched cycloalkanes in the diesel and jet fuel range from lignocellulosic biomass-derived platform chemicals. Full article

TiO₂ shows improved photocatalytic properties when combined with other oxides, such as ZrO₂. Unfortunately, this material does not exhibit a spectral response in the visible range, but this can be improved by adding WO₃. Here, the effect of the amount of WO₃ and the treatment temperature on TiO₂-ZrO₂-WO₃ materials applied in the solar photocatalytic oxidation of sildenafil was evaluated. The materials were synthesized using the sol–gel method and were characterized by N₂, XRD, UV-Vis RDS, SEM, PL, and XPS. Photocatalytic activity was determined by the degradation and mineralization of sildenafil. The most active photocatalysts were selected for stability testing and to determine the oxidizing species that dominate the reaction mechanism. The optimal amount of WO₃ that improves solar photocatalytic activity at both treatment temperatures was found to be 1% with a reaction mechanism based on OH· and h⁺. WO₃ reduces electron–hole pair recombination. At 500 °C, the crystallinity of the anatase phase is improved, while at 800 °C, the transformation to rutile is suppressed at low WO₃ concentrations. XPS observed the reduction in Ti⁴⁺ to Ti³⁺ and W⁶⁺ to W⁵⁺ in TiO₂–ZrO₂–WO₃ materials, which were found to be photoactive under sunlight with potential for use in industrial-scale reaction systems. Full article

This study investigates the interaction of Ru₃ clusters with pristine and defective anatase (101) TiO₂ surfaces using density functional theory (DFT) to evaluate their structural stability, electronic modifications, and photocatalytic potential. The results show that Ru₃ clusters strongly bind to both pristine and defective surfaces, with oxygen vacancies acting as anchoring sites that further stabilize the clusters. Electronic structure analysis reveals the formation of mid-gap states due to hybridization between Ru and Ti orbitals, extending visible light absorption. On defective surfaces, synergistic effects between Ru₃ clusters and vacancy-induced states further enhance charge separation and reduce recombination. Band structure and wavefunction analyses confirm these findings, highlighting Ru₃-decorated anatase TiO₂ as a promising system for hydrogen evolution and CO₂ reduction. The outcomes of this computational investigation provide valuable insights into the rational design of advanced photocatalysts for sustainable energy applications. Full article