Research on Chemical Intermediates最新文献

Coating Manganese oxide (MnO_x) onto solid substrates is one of the most effective approaches for addressing the inherent agglomeration tendency of powdered MnO_x in practical applications. In this study, we deposited MnO_x onto activated carbon (AC) and improved the catalytic performance for formaldehyde (HCHO) removal by introducing metal platinum (Pt). When evaluated as catalysts in the HCHO catalytic reaction at ambient temperature, the obtained 0.05 wt% Pt-MnO_x/AC catalyst possessed remarkable catalytic and adsorption activity and stability. It could achieve 98%HCHO removal by degrading 1.01 ppm HCHO to 0.02 ppm (0.024 mg/m³) within 2 h in static test at ambient temperature. Further structure-performance investigations revealed the crucial role of metal Pt, which not only improved the oxygen activation capacity but also increased the contents of adsorbed oxygen species and enriched oxygen vacancies; therefore, key intermediates, including performic acid, formate, and CO, can be easily converted. More importantly, the deactivated catalyst regained its full activity after 6 h of air exposure, which was attributed to the rapid regeneration of surface hydroxyl groups through atmospheric O₂ and the oxidation of accumulated intermediates. This study reveals the HCHO catalytic mechanism over Pt-MnO_x/AC and provides valuable insights into the design of high-activity, relatively low-cost environmental catalysts.

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Owing to their distinctive and tunable physicochemical properties, zinc oxide (ZnO) nanoparticles (NPs) have attracted significant attention in cancer therapy as well as photocatalytic applications. The novelty in this work was to use a green approach using pomegranate peel extract to synthesize pure ZnO NPs, Al-doped ZnO NPs, and Al-ZnO/rGO NCs to improve their photocatalytic and anticancer performance. The synthesized materials were characterized in detail by XRD, SEM, EDX, XPS, FTIR, PL, and DLS. XRD results confirmed the high crystallinity of ZnO and indicated increased crystallite size from 17.60 nm to 21.51 nm by doping and rGO incorporation. The SEM image of ZnO NPs showed spherical shapes with uniform distribution on the surface of rGO. EDX verified the existence of Zn, O, Al, and C in the nanocomposites without observable impurities, whereas XPS revealed the elemental composition and oxidation states. FTIR also supported the presence of functional groups, and UV–Vis results showed a decrease in the bandgap energy from 3.34 eV to 3.25 eV due to doping as well as rGO integration. Based on the PL data, it was supposed that better charge separation and improved photocatalytic reaction and biomedical application potential were discerned from these composites. DLS results showed that the zeta potential of pure ZnO NPs, Al-doped ZnO NPs, and Al-ZnO/rGO NCs were − 16.3 ± 8.30 mV, − 20.2 ± 6.86 mV, and 21.0 ± 14.10 mV, respectively. In a photocatalytic experiment, Al-ZnO/rGO nanocomposite showed enhanced degradation efficiency (82.49%) for Brilliant Blue R dye compared to pure ZnO (59.70%). Cytotoxicity evaluations against colorectal cancer (HCT116) cells showed markedly superior anticancer efficacy of Al-ZnO/rGO nanocomposites after both 24 and 48 h, higher than that of pure ZnO and Al-doped ZnO nanoparticles. The findings highlight the combined effect of aluminum doping and reduced graphene oxide incorporation to enhance the photocatalytic and anticancer efficacy of zinc oxide-based nanomaterials.

Vanadium complexes are efficacious catalysts for the oxidation of diverse organic substrates. Immobilizing these complexes on solid supports enhances their chemical and thermal stability, improves catalytic efficiency, and facilitates easy separation from the reaction mixture, thereby minimizing contamination of the final product. A novel vanadium complex of substituted benzimidazole, 2(2'-quinolylbenzimodazole) immobilized on a partially chloromethylated polystyrene cross linked with divinyl benzene copolymer support was synthesized successfully. The supported catalyst was characterized by elemental analyses, TGA, conductivity and magnetic susceptibility measurements, FT-IR and Diffused Reflectance and Electron Spin Resonance spectral analysis. The proposed catalyst revealed positive outcomes in the oxidation reactions of Phenol, p-Nitrophenol, p-Cresol, Benzyl alcohol and p-Chlorobenzyl alcohol in water under ambient reaction conditions with H₂O₂ as an oxidant. The catalyst under ideal concentration and ambient reaction conditions exhibited excellent activity towards the green oxidation of Phenol with 99% conversion with 96% selectivity toward catechol at 60 °C. Similarly, p-nitrophenol exhibited a 95% conversion with 86% selectivity toward p-nitrocatechol. Additionally, the oxidation of p-cresol resulted in a 99% conversion and 92% selectivity toward p-hydroxybenzaldehyde. The catalyst also displayed excellent recyclability and facile separation, underscoring its potential for sustainable oxidation processes. It could be recycled for five turns retaining the catalytic activity of 92 to 94% with negligible leaching of only 0.25% of the embedded metal. The results suggested immobilized vanadium complex as an environmentally benign catalytic system to oxidize phenolic compounds in water.

In this study, a straightforward and eco-friendly approach was developed for the synthesis of biocompatible compounds that include manganese and tannic acid covalently linked with β-cyclodextrin (Mn/TA-βCD and MnTA/βCD). Additionally, a MnO₂/TA-βCD composite was prepared for comparison. FT-IR, UV–vis, TGA, and Fluorescence techniques were used to characterize the prepared samples. TGA analysis demonstrated that MnTA/βCD had better thermal stability than Mn/TA-βCD. An interaction between β-cyclodextrin and tannic acid was confirmed by the fluorescence spectrum. The introduction of tannic acid into the β-cyclodextrin further improved the in vitro antioxidant potential. According to the pyrogallol autoxidation, MnTA/βCD exhibited the highest SOD-like activity (93%), and MnO₂/TA-βCD demonstrated superior efficacy in scavenging hydrogen peroxide (94%). In addition, MTT assay studies confirmed the non-cytotoxic nature of the compounds.

The performance of graphitic carbon nitride (g-C₃N₄)-based cobalt (Co) catalysts (Co-g-C₃N₄, Co@g-C₃N₄) for the hydroesterification of diisobutylene (DIB) was evaluated. In this study, graphite carbon nitride (g-C₃N₄) was synthesized by that thermal decomposition of urea, melamine and thiourea in a muffle furnace. The results showed that the optimal reaction conditions were CO pressure 8.0 MPa, reaction temperature 150 °C and reaction time 10 h. When Co₂(CO)₈-g-C₃N₄ in situ catalyst was used, the conversion of DIB was 94.6% and the selectivity to methyl isononanoate was 90.0%. Similarly, in order to solve the problem of poor reusability of the catalyst, Co(OAc)₂@g-C₃N₄ catalyst system prepared by impregnation method was studied. Under the same reaction conditions for 12 h, only 72.0% conversion of DIB and 89.6% selectivity to methyl isononanoate were obtained, but the catalytic performance was obviously improved compared with in situ catalyst. The catalysts were characterized by scanning electron microscope (SEM), Fourier transform infrared spectrometer (FT-IR), N₂ adsorption–desorption isotherm and so on. In addition, the two catalyst systems are suitable for the hydroesterification reaction of various terminal olefins, and exhibit excellent recovery performance and thermal stability.

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A mild and robust synthetic strategy has been developed for the synthesis of 1,3-thiazolidin-4-one derivatives via a one-pot, three-component reaction of aromatic or heteroaromatic aldehydes, aromatic amines, and thioglycolic acid under solvent-free conditions at 110 °C. The reaction proceeds efficiently in the presence of iron oxide nanoparticles coated with hydroxyapatite (Fe₃O₄/HAP), serving as a heterogeneous solid-base nanocatalyst. This nanocatalyst produces good to excellent yields desired product and offers several practical advantages. Comprehensive characterization of the catalyst was performed using X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and field emission scanning electron microscopy. The new synthetic methodology has a shorter reaction time, a broad-substrate scope, and an eco-friendly and solvent-free approach. Due to its strong magnetic responsiveness, the catalyst can be conveniently recovered using an external magnetic field and reused for five successive cycles with negligible loss in activity.

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A metal-free P-(g-C₃N₄/NCDs) photocatalytic composite was synthesized by modifying graphitic carbon nitride (g-C₃N₄) through a dual strategy of nitrogen-doped carbon quantum dots (NCDs) incorporation and protonation. Under light irradiation, the optimized catalyst achieved 99% degradation of methyl orange within 120 min, exhibiting a reaction rate 50 times higher than that of unmodified g-C₃N₄. Furthermore, the composite demonstrated excellent stability, maintaining high catalytic performance over five consecutive cycles. Characterization results revealed that the dual modification induced a stripping effect on the g-C₃N₄ material. This process optimized the electronic structure of the composite, effectively suppressing the recombination of photogenerated electron–hole pairs. Additionally, adjustment of the band gap structure enhanced the oxidizing capacity of the valence band, thereby improving the overall photocatalytic activity. The synergistic effect of superoxide (•O₂⁻) and hydroxyl (•OH) radicals in substantially boosting the oxidative capacity of P-(g-C₃N₄/NCDs) was unambiguously verified by radical trapping experiments and electron paramagnetic resonance (EPR) spectroscopy. This synergy facilitates the mineralization of organic dye molecules into small inorganic molecules (e.g., CO₂ and H₂O). This metal-free photocatalyst design strategy, focused on material structure optimization, circumvents secondary water pollution from metal leaching, suggesting promising potential for applications in green catalysis and related fields.

New bimetallic Pd–Mn catalysts supported on the carbon material Sibunit have been obtained and studied for the process of producing ethylene by acetylene hydrogenation. The composition, structure, morphology and electronic state of the active phase have been studied in detail depending on the temperature of treatment in hydrogen and the Pd/Mn ratio by XRD, XANES, EXAFS, TEM, XPS. It has been found that the active species are the nanoparticles of intermetallic tetragonal structure Pd₃Mn₂ that formed during the treatment of Pd–Mn/Sibunit in H₂ at 500 °C. Increasing the reduction temperature to 600–700 °C provides an increase in the proportion of the Pd₃Mn₂ phase due to more complete involvement of palladium in the interaction with manganese. Pd₃Mn₂ nanoparticles are less active but more selective than Pd nanoparticles due to changes in the geometry of active sites and their electronic state. It is shown that catalysts containing a twofold molar excess of Mn relative to Pd are characterized by the presence of more dispersed bimetallic particles than samples containing less manganese, due to which they are characterized by higher activity. Pd–Mn/Sibunit catalysts provide a high ethylene yield (up to 75%), which makes them promising materials for the process of acetylene hydrogenation to ethylene.

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Liquid-phase selective oxidation of benzyl alcohol (BZA) by atmospheric O₂ is a sustainable route for the synthesis of benzaldehyde (BZL). Although noble metal catalysts showed excellent activity, the high cost and limited reserves of noble metals underscore the significance of developing efficient non-noble metal-based catalysts. Herein, cerium vanadate (CeVO₄) materials were synthesized by a simple coprecipitation method and employed as heterogeneous catalysts for the selective oxidation of BZA by O₂. Under the same reaction conditions, the CeVO₄ materials demonstrated superior activity to the pure V₂O₅ and CeO₂ samples, affording a high yield of BZL of 69% under a reaction temperature of 120 °C. For the CeVO₄ materials, the catalytic activity correlated well with the percentages of Ce³⁺ and V⁴⁺ species, depending on the preparation temperatures. Moreover, the catalysts could be reused at least five times without significant loss in activity.

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Methylene blue (MB) as a persistent dye poses serious environmental threats, requiring efficient removal methods. In this study, the TiO₂-graphene nanocomposites have been fabricated for MB decomposition under visible-light irradiation. Graphene oxide was synthesized via a modified Hummers method and subsequently incorporated into mixed-phase TiO₂ (44% anatase and 56% rutile) in varying amounts (5–75 wt. %) using a hydrothermal method. The introduction of this oxygen-functionalized reduced graphene oxide (RGO) into the TiO₂ matrix significantly enhanced the photocatalytic activity by increasing the adsorption surface area, reducing the band gap, and suppressing electron–hole recombination.

The nanocomposite with an optimal 50 wt. % RGO content demonstrated nearly complete MB degradation in less than 10 min, fitting a pseudo-first-order kinetic model with a high-rate constant. These results highlight the potential of TiO₂–RGO nanocomposites for effective and rapid dye removal, presenting a promising advance in environmental remediation technologies.