Research on Chemical Intermediates最新文献

In the NH₃ selective catalytic oxidation (NH₃-SCO) reaction, non-noble metal catalysts have attracted much attention due to their low cost and high N₂ selectivity at low temperatures. However, the significant decrease in N₂ selectivity at high temperatures remains a significant challenge. In this work, we treated TiO₂ support with sulfuric acid to balance redox performance and surface acidity, thereby improving the N₂ selectivity of Cu–Ce/TiO₂ catalyst. Compared to Cu–Ce/TiO₂ catalyst, (Cu–Ce/TiO₂)-S_0.05 catalyst (sulfuric acid added during Cu and Ce co-impregnation, where the molar ratio of S to Ti is 0.05) showed a 20.8% increase in N₂ selectivity at 400 °C. After treating TiO₂ with an excessive amount of sulfuric acid, its catalytic activity significantly decreased. This was attributed to the excessive sulfuric acid treatment resulting in the aggregation of Cu species, thereby decreasing the number of redox sites on the catalyst surface and severely disrupting the balance between redox and acid properties. In situ DRIFTS results showed that, in the NH₃-SCO reaction, Cu–Ce/TiO₂ and (Cu–Ce/TiO₂)-S_0.05 catalysts followed dual pathways involving internal selective catalytic reduction and amide (–NH) mechanisms. However, after sulfuric acid treatment, the number of acid sites on the catalyst surface increased significantly, and abundant NH₃ species on the surface could effectively reduce NO_x to N₂ and H₂O through the i-SCR mechanism.

A Fe/Cr/Cu catalyst pellet was developed for the high-temperature water–gas shift reaction (HT-WGSR) to enable efficient hydrogen production from syngas derived from waste plastic gasification. The Fe/Cr/Cu catalyst powder was synthesized via a co-precipitation method and subsequently formed into pellets through compression molding. HT-WGSR performance was evaluated at CO:H₂O feed ratios of 1:2–1:4 and operating temperatures of 300–400 °C under a gas hourly space velocity of 10,000 h⁻¹. The highest CO conversion (84–91%) was obtained at 350 °C with a CO:H₂O ratio of 1:2, while the maximum H₂ selectivity (0.44–0.90) was achieved at 350 °C with a CO:H₂O ratio of 1:3. These results highlight the Fe/Cr/Cu catalyst pellets as promising candidates for sustainable hydrogen production in HT-WGSR applications.

Compared to other reactive oxygen species, singlet oxygen (¹O₂) exhibits unique advantages, including high selectivity and strong oxidative capacity, for the targeted oxidation of pollutants. However, its production is often limited by the narrow spectral response and low intersystem crossing efficiency of conventional photocatalysts. In this study, we constructed a composite photocatalytic system based on metal–organic frameworks (MOFs) loaded with gold nanoparticles (Au NPs) to elucidate the enhancement mechanism by which singlet oxygen generation is enhanced through synergistic modulation of localized surface plasmon resonance (LSPR) and excitonic states. The introduction of Au NPs significantly enhanced the LSPR absorption of the material, effectively promoting the conversion of excitons from singlet-to-triplet states. This was achieved by lowering the energy barrier for singlet-to-triplet conversion (Δ_EST decreased from 0.172 eV to 0.162 eV), thereby accelerating the intersystem crossing process and improving ¹O₂ generation efficiency, consequently, the system enabled efficient removal of p-chlorophenol. This work proposes a novel “LSPR–exciton regulation–photothermal synergy” mechanism, offering new strategies for the rational design of high-activity photosensitizers and targeted pollutant oxidation.

In photocatalytic degradation of pollutants, hydrogen-related defects on the catalyst surface inhibit the generation of highly reactive superoxide radicals (·O₂⁻). Therefore, strategies to mitigate such defects are crucial for enhancing photocatalytic efficiency. To address this challenge, ZnWO₄/hydrothermal red phosphorus (ZnWO₄/HRP) S-scheme heterojunction photocatalysts were successfully prepared via a simple hydrothermal method, constructing a compact interfacial structure where rod-shaped ZnWO₄ uniformly attaches to the HRP surface. Photocatalytic performance tests revealed that the composites exhibited excellent catalytic activity for rhodamine B (RhB) degradation, with a rate constant of 0.21 min⁻¹ within 15 min-3.5 and 21 times higher than those of individual HRP and ZnWO₄, respectively. Moreover, due to the robust chemical structure and strong interfacial bonding between ZnWO₄ and HRP, the composite maintains high photocatalytic stability across multiple catalytic cycles. Mechanistic analysis demonstrates that the S-scheme heterojunction effectively suppresses the formation of hydrogen-related defects on the ZnWO₄ surface, significantly reducing surface defect state density. This inhibition enhances photogenerated carrier separation, accelerates charge transfer, and facilitates the efficient generation of ·O₂⁻. By adopting a heterojunction strategy to address hydrogen-related defects, the catalyst’s visible-light absorption capacity, photoelectric conversion efficiency, and radical generation efficiency was enhanced, while carrier recombination was suppressed. These findings provide new insights for designing high-efficiency heterojunction photocatalysts and highlight their promising potential in photocatalytic removal of organic pollutants.

Graphical abstract

This research focuses on the synthesis of NiO nanoparticles via a bio-fabrication method, where almond peel extract serves as both a stabilizing and capping agent. The effectiveness of these nanoparticles in the photocatalytic treatment of the organic pollutant was comprehensively evaluated, considering various influencing factors, including organic pollutant concentration, catalyst dosage, and pH. The structural, optical, morphological, and functional groups of the fabricated materials were examined by employing XRD, UV, SEM, and FTIR techniques. The fabricated nanoparticles exhibited an average crystallite size of 20.98 nm. The degradation potential of the fabricated materials was found to be decreased with increasing the initial pollutant concentration, while it improved with a higher catalyst dosage and increasing the solution pH during the photocatalysis. NiO nanoparticles demonstrated the greatest photocatalytic removal of brilliant green and amoxicillin after 120 min solar light exposure, reaching degradation efficiency of 79.13% and 43.05% for brilliant green and amoxicillin, respectively. The removal of amoxicillin follows pseudo-first-order kinetics with an R² value of 0.89882, while the breakdown of the brilliant green follows a first-order reaction with an R² value of 0.96426. This eco-friendly synthesis procedure reduces the environmental impact associated with the conventional chemical process by harnessing the renewable resources of almond peel, offering a sustainable combat against environmental degradation.

The synthesis of bioactive chromene derivatives is of great significance due to their diverse pharmacological properties. In this study, a novel magnetically recoverable nanocatalyst, Fe₃O₄-β-cyclodextrin-graphene oxide (Fe₃O₄-β-CD-GO), was developed and thoroughly characterized using techniques such as Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier-Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), and Vibrating Sample Magnetometer (VSM), confirming its successful fabrication, stability, and magnetic properties. This heterogeneous catalyst was employed for the efficient and green synthesis of 2-amino-3-cyano-4H-chromenes in aqueous media at 80 °C, showing excellent yields up to 95% within short reaction times (10–60 min). Optimization studies highlighted the superior performance of water as a solvent, with catalyst loading (0.7 mol%) and temperature significantly influencing reaction efficiency. The catalyst demonstrated remarkable recyclability, maintaining high activity over at least eight cycles, facilitated by easy magnetic separation. A plausible reaction mechanism was proposed, involving activation of electrophiles and nucleophiles via hydrogen bonding and acid–base interactions. The method proved versatile, accommodating various aldehyde substrates with different electronic properties, and scalable for larger-scale synthesis. These findings underscore the catalyst’s potential for sustainable, cost-effective, and efficient organic transformations, advancing green chemistry protocols in pharmaceutical and material synthesis.

Graphical abstract

Benzyl alcohol (BOL), an aromatic compound bearing oxygen-containing functional groups, is capable of forming BOL-based hyper-cross-linked resin (BOL-HCPs) with chloromethylated polystyrene resins (CMPs) via a sequence of chemical reactions. A combination of characterization techniques, including BET, FT-IR, SEM-Mapping, XPS, XRD, contact angle measurement, and TGA, was confirmed the successful preparation of the adsorbent. Notably, the incorporation of BOL significantly increases both the specific surface area (S_BET) and hydrophilicity of the adsorbent. BOL-HCPs, prepared by Friedel–Crafts alkylation and nucleophilic substitution reaction, exhibited excellent phenol removal capacity from aqueous solutions. The Langmuir isotherm model better describes the resin’s equilibrium adsorption, showing a max capacity of 275.2 mg/g at 298 K. Kinetic analysis reveals that the adsorption of pollutants reaches equilibrium rapidly within 90 min, which is consistent with the pseudo-first-order model. Owing to its favorable S_BET, abundant micropores/mesopores, as well as hydrogen bonding interactions, the adsorbent enables highly efficient phenol adsorption. This work offers a new strategy for phenol removal from aqueous solutions.

Graphical Abstract

This study outlines an easy, efficient and environmentally sustainable method for the green synthesis of manganese dioxide (MnO₂) nanoparticles using an extract from Psidium guajava leaves. The catalytic activity of MnO₂@Ag–S–CH₂–COOH nanocatalyst was explored for the one-pot synthesis of hydrazinyl thiazole derivatives, utilizing a three-component reaction involving different aryl aldehydes, phenacyl bromides, and thiosemicarbazide. A number of techniques were used to characterize the MnO₂@Ag–S–CH₂–COOH nanocatalyst, field emission scanning electron microscopy (FE-SEM), Brunner–Emmett–Teller (BET), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray (EDX). The structures of each newly synthesized derivative of hydrazinyl thiazole have been confirmed via the use of nuclear magnetic resonance (¹H and ¹³C NMR), fourier-transform infrared (FTIR) and high resolution mass spectrometry (HRMS). The MnO₂@Ag–S–CH₂–COOH nanocatalyst was readily extracted from the reactions with the use of an external magnet and could be reused five times without experiencing a substantial loss in efficacy. The synthesized compounds demonstrated promising results when assessed in vitro for their antimicrobial and anticancer activities. The anticancer efficacy of the synthesized hydrazinyl thiazole compounds were assessed in vitro against the MCF-7 human breast cancer cell line using the MTT assay. Among them, compounds 4a and 4e exhibited notable anticancer effects, with IC₅₀ values of 82.30 ± 0.58 and 84.25 ± 0.28 μg/mL respectively.

A series of Pt-based catalysts supported on morphology-controlled ZSM-5 zeolites were synthesized and applied for toluene catalytic oxidation. The results demonstrated that the catalyst Pt supported on sheet-like ZSM-5 (Pt/S-ZSM) exhibited significantly higher activity than those supported on chain-like ZSM-5 (Pt/C-ZSM) and unmodified ZSM-5 (Pt/N-ZSM). The sheet-like morphology ZSM-5 zeolites exhibited a toluene saturation capacity of 65.17 mg·g⁻¹, with breakthrough time and saturation adsorption increased by 2.4-fold and 1.4-fold, respectively, compared to unmodified N-ZSM-5. Notably, compared to 0.5wt% Pt/C-ZSM, the 0.5wt% Pt/S-ZSM catalyst exhibited a significantly lower apparent activation energy (11.63 kJ·mol⁻¹), confirming the superior suitability of S-ZSM as a Pt support. This was further evidenced by its exceptional catalytic activity, achieving 90% toluene conversion (T₉₀) at just 181℃. The Pt/S-ZSM showed well catalytic activity and structural stability during the toluene catalytic combustion, which reflected a promising catalyst for practical application.