Research on Chemical Intermediates最新文献

This research evaluates the use of metal nanoparticles, produced from the pyrolysis of metal–organic frameworks, as catalysts for breaking down organic pollutants. The study specifically examines CoC and CoC/Zn nano-catalysts, which were synthesized, characterized, and tested against pollutants like p-nitrophenol (PNP) and methyl orange (MO) using sodium borohydride. SEM analysis showed that the nanoparticles ranged in size from 50 to 200 nm, while TEM revealed smaller sizes from 20 to 100 nm. EDX analysis confirmed zinc’s presence in CoC/Zn, and XPS analysis detected various elements, including C, N, O, Cl, Co, and Zn in CoC/Zn, with the absence of Zn and presence of K in CoC. Additional tests like EDAX and XRD confirmed the presence of Co and Zn in the samples. During the pyrolysis, graphite was formed, as indicated by Raman spectroscopy. BET analysis showed that Co/C had a surface area of 100 m²/g, which was significantly higher than CoC/Zn, attributed to the use of K₂EDTA during Co/C’s synthesis. In degradation tests, CoC outperformed CoC/Zn, with first-order rate constants of 0.128 min⁻¹ for PNP and 0.425 min⁻¹ for MO, showing higher catalytic efficiency and durability—lasting 18 cycles for PNP and 34 cycles for MO. Although CoC/Zn had lower performance, it was noted for its efficiency. In terms of energy storage, CoC/Zn and CoC displayed specific capacitance values of 470 F/g and 560 F/g, respectively, and showed high durability by retaining about 93.46% of their original capacitance after 2300 cycles. These findings underscore the potential of CoC as an effective, durable catalyst for environmental cleanup and both materials as viable, cost-effective options for energy storage.

The use of bifunctional catalysts, combining methanol synthesis and zeolite components, has been cleverly expanding to the hydrogenation of CO₂ into liquefied petroleum gas (LPG). However, such catalysts in this reaction displayed low catalytic efficiency due to the mismatch of the two components. In this study, an efficient strategy was realized via physically coating β zeolite onto the CuZnAl methanol catalyst, resulting in a shell thickness controllable core–shell encapsulated catalyst, denoted as CuZnAl@β. Sufficient characterization proves that the micro-coupling structure between methanol active sites and zeolite acid sites is designed reasonably and successfully, as consequently, the zeolite capsule catalysts embody a significant improvement toward LPG selectivity. Hence, the CuZnAl@β catalyst reached a high selectivity to LPG at 77.9% with 21.3% CO₂ conversion, under a reaction pressure of 2.0 MPa and a temperature of 320 °C. The strategy employed in this study could offer valuable insights into guiding catalyst design.

Catalyst deactivation due to coke formation is a key issue in dimethyl ether to gasoline (DTG) process, and it is significant to investigate the change of catalyst properties during reaction to inhibit the rapid deactivation of catalyst. Here, the nanocrystalline H[Fe,Al]ZSM-5 zeolite synthesized hydrothermally was evaluated as catalyst for DTG process in different reaction time. The detailed characterizations of fresh and spent catalysts were carried out, such as UV-Vis, XRD, SEM, N₂ adsorption-desorption and NH₃-TPD, and the coke formation and its location in catalyst were studied. The results indicated that DTG reaction mainly occurred at strong acid sites of nanocrystalline H[Fe,Al]ZSM-5, and Brønsted acid sites were the most active. Furthermore, the catalysts even with small amount of B acid still possessed the higher catalytic activity during stable period of DTG reaction. The coke deposition was produced in DTG reaction, and at the initial stage, coke precursors including alkylbenzenes retained inside the micropores. These precursors grow gradually to form polycyclic aromatic hydrocarbons, which overflow on the outer surface with increasing reaction time, and then mainly accumulates on the external surface of catalyst. The coke occludes the active sites and hampers the molecular diffusion, eventually causing activity loss. The catalyst deactivation was mainly caused by the blockage of micropores and coverage of B acid sites due to coke deposition. And the deactivated catalysts could be oxidized and regenerated in air at 550–650 °C.

A novel nanomaterial namely Si-propyl-functionalized 4,4′-bipyridine-1,1ʹ-diium bisulfate tetrachloroferrate anchored to rice husk-derived nano-silica (PBBTRS) was fabricated, and analyses involving EDS (energy-dispersive X-ray spectroscopy), elemental mapping, FE-SEM (field emission scanning electron microscopy), XRD (X-ray diffraction), FT-IR, Raman and inductively coupled plasma-optical emission spectroscopy (ICP-OES) were utilized to corroborate its structure. Thereafter, PBBTRS was applied as a highly efficacious, recoverable and dual-functional catalyst for the construction of N,N′-alkylidene bisamides from aryl aldehydes and primary amides under solvent-free conditions. A valuable improvement in this methodology is performing the reaction under mild conditions (60 °C).

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Reverse micellar templated nickel carbonate nanospheres are employed to prepare a double-phase inversion Pickering emulsion. Nickel carbonate nanospheres are synthesized within the core of reverse micelles, composed of Span 80/1-butanol/toluene/water. The evaluation of nanospheres within the core of reverse micelles was conducted using TEM and FESEM instrumentations. Micromorphological analysis of the results indicated a two-phase formation process for the nanospheres: nucleation phase (5–15 min) followed by a growth phase (15–60 min). At neutral pH (⁓ 6.16), the synthesized nanospheres are positively charged (+ 5.342 mV). Due to their extreme hydrophilic properties, they alone cannot provide the desired stability to O/W Pickering emulsions. With the assistance of negatively charged head groups, anionic surfactants like SDS and nickel carbonate nanospheres are involved in in situ hydrophobization through the electrostatic adsorption of surfactant molecules onto their surfaces. It eventually provides stability to the toluene–water Pickering emulsions, and an intriguing double-phase inversion is detected. The first-phase inversion (O/W to W/O) occurred due to the increased hydrophobicity of modified nickel carbonate nanospheres where SDS (≤ 7 mM) molecules formed a monolayer on the nickel carbonate surface. The second-phase inversion (W/O to O/W) is detected due to the bilayer adsorption (through tail-to-tail interaction) of SDS (> 7 mM) on nickel carbonate nanospheres, thereby converting the hydrophobic nickel carbonate nanocomposites to hydrophilic again. Consequently, the wettability of nickel carbonate-SDS nanocomposites can shift from hydrophilic to hydrophobic and back again to hydrophilic, triggering the evaluation of double-phase inversion Pickering emulsions.

The simple extrusion method used to combine metakaolin (MK) with aminoethyl-3-aminopropyltriethoxysilane (AEAPTES) to create composite (MK/AEAPTES) is described in this article. Owing to amine group inherent on MK, it exhibited a basic nature. The novel basic catalyst is used for the synthesis of pyrazolyl phosphonates by Michael-addition reaction. Significant product yields, environmental friendliness, rapid reaction durations, broad range of substrate compatibility, and lack of hazardous solvent requirement make these reactions remarkable. Furthermore, there is no appreciable decrease in activity subsequently five recycles of the catalyst and catalyst separation using a straightforward filtration technique without any extraction. The synthesized derivatives were characterized by ¹H, ¹³C NMR, and ³¹P NMR & FT-IR analysis. Synthesized composite is analyzed by FT-IR, XRD, and SEM–EDX, investigation is compared with MK. The recycled catalyst is also checked by FT-IR, XRD, and SEM–EDX analysis.

Enhancing photocatalytic selectivity is essential for the effective and efficient utilization of catalysts. In this study, a molecularly imprinted polymer POPD/Bi₂O₃/CeO₂, designated as MIP-POPD/Bi₂O₃/CeO₂, was successfully synthesized via photopolymerization using pyridine as a template. The resulting MIP-POPD/Bi₂O₃/CeO₂ was characterized through Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, N₂ adsorption–desorption isotherms, and UV–vis diffuse reflectance spectroscopy. MIP-POPD/Bi₂O₃/CeO₂ exhibited enhanced charge transfer and efficient separation of photogenerated carriers, as confirmed by photoluminescence measurements, electrochemical impedance spectroscopy analysis, and photocurrent response (I–t) curve evaluations. When the concentration of pyridine in simulated oil reached 80 µg/g, with an amount of 1.6 g/L for MIP-POPD/Bi₂O₃/CeO₂ and an illumination time of 120 min, the degradation rate of pyridine achieved 80%, which is 1.57 times greater than that observed using NMIP-POPD/Bi₂O₃/CeO₂. After an adsorption for 30 min, MIP-POPD/Bi₂O₃/CeO₂ exhibited the adsorption capacity of 5 mg/g, attributed to the large number of molecularly imprinted pores on its surface. In various mixed systems, the selectivity coefficients for pyridine using MIP-POPD/Bi₂O₃/CeO₂ consistently exceeded 1.5, which can be attributed to the selective adsorption properties of the imprinted pores within the polymers that preferentially recognize and remove pyridine. Furthermore, after five cycles, the photocatalytic degradation rate of pyridine by MIP-POPD/Bi₂O₃/CeO₂ can still reach 77%, indicating that MIP-POPD/Bi₂O₃/CeO₂ possesses good stability. Trapping experiments demonstrated that superoxide radicals (·O₂⁻) and holes (h⁺) were the predominant active species in photocatalytic reactions. Additionally, a proposed mechanism for photocatalytic denitrification utilizing MIP-POPD/Bi₂O₃/CeO₂ was presented. This study provides a promising strategy for designing Bi-based molecular imprinting photocatalysts aimed at efficiently removing low-concentration, highly toxic target pollutants from mixed samples.

In this work, a stable bimetallic hydrotalcite-derived NiCu/MgAlO catalyst and O₂ as oxidant were used for the toluene oxidation to produce the valuable benzyl alcohol (PhCH₂OH) and benzaldehyde (PhCHO) under solvent-free and additive-free conditions. This strategy gave 7.2% toluene conversion with 70.7% selectivity to PhCH₂OH & PhCHO. Multiple characterizations showed that highly dispersed metallic Cu and Ni were anchored on the support surface and a chemical bonding interaction occurred between the metallic Ni and the MgAlO. The metal–support interaction contributed to the formation of active Ni⁰ species and NiCu alloy with abundant oxygen defects, resulting in excellent catalytic activity and acceptable stability. A plausible reaction mechanism for the catalytic oxidation of toluene over NiCu/MgAlO catalyst has been proposed. The attractive feature of the present catalytic oxidation system compared to conventional methods was its ability to achieve high selectivity for the desired target product. The further advantage of NiCu/MgAlO catalyzed toluene oxidation was that the reaction temperature and time could be below 180 °C and 2 h, thereby minimizing energy consumption and reducing effluent wastewater, which has potential application prospects.

The quest for sustainable and eco-friendly chemical processes has driven the exploration of greener synthetic methodologies for the development of biologically potent scaffolds. In this study, we aimed to design an efficient and sustainable synthetic route for the generation of pyrazolo[3,4-b]pyridine derivatives, which are recognized for their significant pharmacological properties. Meglumine as a low-cost, reusable, and eco-benign catalyst was used in a one-pot, three-component reaction using Meldrum’s acid, substituted aldehydes, and 3-methyl-1H-pyrazol-5-amine at room temperature. This method afforded 15 derivatives, including six new compounds, with excellent yields (82–96%) within just 5–25 min. The synthesized compounds were well corroborated using spectral analysis. The method entails several benefits including the use of an eco-friendly catalyst, simple separation, and reusability over five cycles, gram-scale synthesis, and favorable green chemistry metrics. Additionally, the in silico studies demonstrated the anti-inflammatory and anti-arthritic potential of the synthesized compounds. The compounds were docked within the binding site of the selected PDBs, 3G3N (cAMP phosphodiesterase inhibition) and 7F2W (Gout therapy). The present work introduces these compounds as future anti-inflammatory and anti-arthritic agents.

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This research work includes a detailed investigation of the synthesis, spectroscopic characterization and biological properties of Schiff bases ligand derived from 1,8-diamminonapthalene and 5-bromosalicyaldehyde along with their transition metal complexes. The compounds were meticulously characterized employing sophisticated spectral techniques that are FT-IR (Infra-red), analytical, ¹H-NMR (Proton Nuclear Magnetic Resonance), SEM (Surface morphology analysis), ESI–MS (Electrospray Ionization Mass Spectrometry), PXRD (Powder X-ray Diffraction) and ESR (Electron Spin Resonance). The spectroscopic data reported that the ligand exhibits a tetradentate binding mode, while the metal complexes demonstrate hexa-coordinated geometries. Additionally, DFT investigation was executed employed B3LYP/LanL2DZ as basis set to optimize geometry and evaluate molecular electrostatic potential surfaces. In vitro antimicrobial studies were explored against gram +ve bacteria, gram −ve bacteria and fungal strains. Among these, the copper chloride complex (3) displayed the highest efficacy possessing a minimum inhibitory concentration (MIC) of 0.0094 µmol/mL. Molecular docking investigations were executed to evaluate the binding affinities of the synthesized compounds against a cholesterol lowering agent (2OBD) and HeLa cancerous cells (6I2I). The results indicated that cobalt (1) and nickel chloride (2) complexes exhibit the lowest binding affinities, suggesting higher potency. Additionally, the synthesized compounds demonstrated greater effectiveness against HeLa cancerous cells compared to the 2OBD receptor. The in silico ADME analysis discloses the therapeutic usability of the synthesized compounds.

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