Research on Chemical Intermediates最新文献

The efficient degradation of dye pollutants continues to pose a significant challenge in wastewater treatment, primarily due to constraints in degradation efficiency and complications in catalyst recovery. To address these issues, a novel catalyst has been synthesized utilizing polyacrylonitrile fibers as a support material, which were subsequently loaded with iron-based metal–organic framework through a solvothermal approach. This catalyst, when combined with hydrogen peroxide (H₂O₂), forms a heterogeneous Fenton catalytic system that promotes the degradation of methyl orange (MO) in wastewater. A thorough investigation was conducted to examine the catalytic degradation performance of dyes and the underlying reaction mechanisms. The catalyst demonstrates outstanding performance in dye degradation, achieving 95.7% removal of methyl orange under ambient conditions. Moreover, it retains over 80% degradation efficiency after four consecutive reaction cycles, highlighting its strong recyclability and minimal loss of catalytic activity. Radical quenching experiments and electron paramagnetic resonance analyses confirm that the primary reactive oxygen species involved are hydroxyl radicals (·OH) and superoxide anions (·O₂⁻). Furthermore, both Fe^II and Fe^III ions can be recycled and regenerated in-situ, thereby continuously catalyzing H₂O₂ to produce ·OH and ·O₂⁻, which facilitates the sustained mineralization of dye molecules, thus enabling high dye degradation.

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This work reports the environment-friendly synthesis of nature-derived biochar-based catalyst for synthesis of pharmaceutically significant 2,3-dihydroquinazolin-4(1H)-ones. A Magnetic biochar catalyst was synthesized from coconut waste using a simple hydrothermal reactor followed by 2-step functionalization steps to achieve sulphonated magnetic biochar, Fe@SO₃H-BC. The structural and morphological characterization of the synthesized catalysts was done using XRD, FTIR, FESEM and EDS. The catalytic activity of Fe@SO₃H-BC was studied for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones by condensation of 2-aminobenzamide with carbonyls including acetophenones and aldehydes in solvent-free conditions, resulting in moderate to high yields 83–94% and 70–95%, respectively. The methodology offered advantages by giving an operationally easier and greener chemical route for fabrication of environmentally derived biochar-based catalyst showing notable catalytic activity, recyclability and versatility.

Hydrogen is recognized as a clean and efficient energy carrier, and photocatalytic hydrogen generation represents a pivotal technology for sustainable energy development. In this work, a highly active noble metal-free ZnCo₂O₄/ZnO/C composite has been successfully synthesized via in situ carbonization of a ZnCo-based Prussian blue analogue (PBA), exhibiting remarkable photocatalytic hydrogen generation activity. Under simulated solar irradiation, the optimized composite achieves a high hydrogen generation rate of 2039.3 μmol/(g·h), along with excellent stability. The significantly enhanced photocatalytic activity originates from a unique S-scheme heterojunction charge transfer mechanism and multi-component synergistic effects. Specifically, the intimate interfacial contact among graphitic carbon, ZnCo₂O₄, and ZnO facilitates efficient separation and migration of photogenerated electron–hole pairs. The S-scheme mechanism not only preserves photogenerated electrons with strong reduction capability but also enhances charge carrier utilization. Furthermore, the graphitic carbon improves the electrical conductivity and light-harvesting capability. These factors are responsible for the remarkable photocatalytic performance and good stability. This work provides a compelling demonstration of utilizing PBA-derived carbonization as a versatile platform for fabricating efficient, stable, and scalable photocatalysts for practical hydrogen production.

Conventional synthetic methods for organic compounds are associated with significant environmental concerns, primarily due to the reliance on metal-based catalysts. Furthermore, the employment of toxic solvents combined with prolonged reaction durations presents substantial obstacles to the commercial scalability and practical application of these approaches. In this study, we developed a sustainable green electrode by functionalizing fullerene oxide with L-alanine and incorporating MIL-101@Fe metal–organic frameworks. This innovative approach is designed for enantioselective electro-organic carboxylation in a NaCl electrolyte. The study examines how the biocompatibility of L-alanine and the structural robustness of MIL-101@Fe enhance catalytic efficiency while maintaining environmental sustainability. Functionalizing fullerene oxide with L-alanine improves the electrode's selectivity for the desired enantiomers and increases electron transfer efficiency. The resulting catalytic substrate, oxC60-Ala-MIL101@Fe, was characterized employing various analytical techniques, including EDX, TGA, SEM, EDS, BET, CV, XPS, FT-IR, and DFT calculation to assess its morphology, thermal stability, elemental composition, surface area, and electrochemical behavior. To evaluate the electrode’s performance, we conducted the electro-organic carboxylation of ethylbenzene 1(a-l) derivatives under electro-organic synthesis conditions, yielding various (R)-2-phenylpropanoic acids 4(a-l) with excellent yields (92–97%). Optimal results were obtained at a current of 10 mA, over a duration of 2 h, and at room temperature and Ala-MIL101@Fe exhibited good performance for up to 9 cycles. The products were confirmed using ¹HNMR, CHN analysis, FT-IR spectroscopy, and melting point determination.

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The generation of hydrogen gas through the catalytic hydrolysis of sodium borohydride (NaBH₄) has garnered significant interest in recent years. The primary research challenge remains the development of effective and reusable catalysts. This research details the development of Co/MnFe₂O₄ catalysts aimed at facilitating the hydrolysis of sodium borohydride (NaBH₄), employing MnFe₂O₄ as the support material. The support was synthesized through a co-precipitation method, while the catalysts were produced via an impregnation-chemical reduction technique. The characterization of the catalysts was performed using X-ray diffraction, field emission scanning electron microscopy, X-ray fluorescence, vibrating sample magnetometry, and nitrogen adsorption–desorption measurements. The study initially explored the effects of calcination temperature of the supports and the amount of loaded cobalt on the hydrogen generation process. Notably, catalysts supported on MnFe₂O₄ calcined at 400 °C demonstrated greater activity, with 30% Co/MF-400 catalyst yielding 3533 mL.min⁻¹.g_cat⁻¹of hydrogen during NaBH₄ hydrolysis. The enhanced catalytic performance of the MF-400 supported catalysts was attributed to their small crystallite size or prominent number of defects and high magnetic properties. In addition, 30Co-MF400 showed high specific surface area of 120.1 m².g⁻¹. Subsequently, various parameters were examined over 30Co/MF-400, including catalyst dosage (10–25 mg), concentrations of NaOH (1–7 wt.%), temperature (25–45 °C), and catalyst reusability. The activation energy (E_a) for the 30% Co/MF-400 catalyst was found to be 27.1 kJ/mol, as determined through the application of the rate expression and the Arrhenius equation. The 30% Co/MF-400 catalyst showed a 44% decline in catalytic performance after being used for four cycles.

A simple synthetic method was developed to fabricate three transition metals (M = Ni, Cu, and Zn) doped α-Fe₂O₃ catalysts via a solvothermal approach eliminating the need for a precipitation agent. The synthesized nanocatalysts were characterized using XRD, FT-IR, FE-SEM, EDS, and UV–Vis techniques, and their activity was optimized for the N-formylation of aniline under solvent-free conditions at room temperature. A study of surface morphology revealed that we successfully prepared microspheres of α-Fe₂O₃, Ni–Fe₂O₃, Cu–Fe₂O₃, and Zn–Fe₂O₃. All forms doped represented higher catalytic activity compared to the pristine α-Fe₂O₃, due to a synergistic effect resulting from the presence of transition metals along with Fe. Among all the as-synthesized doped catalysts, Cu–Fe₂O₃ showed the highest activity due to the greater electronegativity of Cu compared to that of Ni or Zn. Thus, Cu–Fe₂O₃ nanocatalyst was selected for the chemoselective transformation of various amines to the corresponding formamides as a sole product (average reaction time: 14 min, average conversion: 90%, average TOF: 0.42 min^–1). Finally, the catalyst could be reused for up to six runs without notable decrease in its activity.

Greenhouse gas emissions remain a critical global concern. The adsorption and separation of biogas, primarily comprising carbon dioxide (CO₂) and methane (CH₄), present significant challenges. In this study, a modified chabazite zeolite containing different fractions of potassium and sodium as extraframework cations was used as an adsorbent. For the adsorption/separation of a mixture of CO₂ and CH₄ at 33:67 vol% at 298 K and 250 kPa, the 94K/Na-chabazite adsorbent (molar ratio of extraframework cations potassium (K) and sodium (Na) is 94:6) displays superior performance of effective separating this mixture. It exhibits the highest CO₂ adsorption capacity of 2.68 mmol/g and dynamic selectivity for CO₂/CH₄ of 9.26 compared to chabazite adsorbents with K:Na ratios of 25:75 and 100:0. With larger cation of K, 100K-chabazite can create a pore constraint that selectively hindered the diffusion of larger CH₄ molecules while allowing CO₂ diffusion to a greater extent. In addition, the extraframework cation of Na, which has a higher electronegativity and cationic density than the K cation, contributes to a stronger electrical field gradient within the chabazite structure, thereby enhancing CO₂ adsorption. The balance between these properties contributes to a greater performance. However, the fastest CO₂ adsorption kinetics depend on the presence of a large amount of Na cations in the structure. Compared to benchmark commercial Na-X and Na-A zeolites, 94K/Na-chabazite is outperform for CO₂ adsorption capacity, dynamic selectivity, and CO₂ adsorption kinetics. The excellent architectural structure, high density of adsorption sites, and appropriate composition of 94K/Na-chabazite in dynamic separation experiments highlight its potential as a promising and competitive adsorbent for the industrial separation of CO₂ and CH₄.

In this manuscript, we report an unique, one pot, one step synthesis of Fe₃O₄ nanoparticles. The protocol for synthesis of nanosized Fe₃O₄ was developed using only Benzyl Amine and Fe(II)acetate precursor via microwave route. Microwave route enables the synthesis of Fe₃O₄ nanoparticles in short duration and eliminates the need of several chemicals. These salient features make the entire synthetic process environment benign as per green chemistry principles. The morphology and other properties of synthesized nanoparticles were studied by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy analysis (XPS), Raman spectroscopy, Field Emission Scanning Electron Microscopy (FE-SEM), and High-Resolution-Transmission Electron Microscopy (HR-TEM). As-synthesized Fe₃O₄ nanoparticles exhibit efficient catalytic transfer hydrogenation of furfural using isopropanol as the solvent and hydrogen source, and provide furfuryl alcohol in good yield. This nanosized Fe₃O₄ was easily removable using magnet and exhibits good reusability. It is observed that acidic-basic sites of nanosized Fe₃O₄ play a vital role in catalytic transfer hydrogenation reaction.

A novel and environmentally benign solid catalyst was successfully synthesized through hydrothermal treatment of rice husks with phosphoric acid for the efficient production of levulinic acid from fructose. The physicochemical properties of the synthesized catalyst were investigated using nitrogen physisorption, X-ray diffraction, thermogravimetric analysis, potentiometric titration, temperature-programmed reduction, scanning electron microscopy, Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy. Batch reactions for the transformation of fructose into levulinic acid were carried out in a high-pressure Parr reactor under controlled conditions. The experiments were performed within a temperature range of 130–170 °C and over reaction times spanning from 1 to 7 h. Aqueous fructose solutions at concentrations between 5 and 20 wt% were tested using a fructose-to-catalyst mass ratio between 2.8 and 11.1, with the system pressurized to 10 bar using nitrogen to maintain an inert atmosphere and suppress undesired side reactions. The catalytic system demonstrated high efficiency in promoting the acid-catalyzed dehydration of fructose to 5-hydroxymethylfurfural, followed by its subsequent rehydration to levulinic acid. The results showed that a maximum levulinic acid yield of 55% was achieved under optimal conditions: a 10 wt% fructose concentration, a fructose-to-catalyst mass ratio of 3.7, a reaction temperature of 150 °C, and a reaction time of 5 h.

Underwater superoleophobic materials have excellent underwater oil resistance due to their special wettability surface, which can cope with oil spill accidents and oily wastewater treatment. In recent years, metal-based underwater superoleophobic materials have attracted tremendous attention in the field of oil–water separation. However, the current methods for fabricating underwater superoleophobic materials have some shortcomings, such as complex preparation process, high cost, and secondary pollution. In this work, calcium carbonate nanoclusters (CaCO₃–NCs), the product of thermal decomposition of calcium acetylacetone, were anchored on the surface of stainless steel mesh (SSM) by impregnation-combustion method to fabricate an underwater superoleophobic material (CaCO₃–NCs@SSM). The samples were characterized by field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), energy-dispersive X-ray spectrometer (EDS), X-ray photoelectron spectrometer (XPS), and X-ray diffractometer (XRD). These results show that CaCO₃–NCs can be uniformly and compactly anchored on the surface of SSM by impregnation-combustion method. Moreover, the oil–water separation capacity and the reusability of the samples were also evaluated by a self-made oil–water separation device. CaCO₃–NCs@SSM possesses excellent underwater superoleophobic property because of its uniform and dense hydrophilic micro–nanostructure on the surface, which can absorb water to form a water film. It can also be known from the contact angle test that the underwater oil contact angles of ethyl acetate, corn oil, dichloromethane, chloroform, liquid paraffin, and diesel oil on the material surface are all greater than 150°. Furthermore, the sandpaper abrasion test demonstrated that CaCO₃–NCs@SSM has excellent mechanical durability. In the oil–water separation experiment, the separation efficiencies of this material for different oil substances all exceeded 98%, among which the separation efficiency of chloroform was 99.5%. In addition, CaCO₃–NCs@SSM maintains a separation efficiency of more than 97% over 60 consecutive cycles of oil–water separation. In summary, the underwater superoleophobic material proposed in this paper has a facile preparation method and high oil–water separation efficiency, which has great potential in solving oil spill accidents and oily wastewater treatment problems in harsh environments.