Catalysis Letters最新文献

Photocatalysis purifies industrial paper wastewater by selectively breaking bonding bonds in lignin. To address the shortcomings of single photocatalysts such as narrow photoresponsive region, high photogenerated carrier complexation rate, and low photocatalytic activity. In this paper, Mg and N doped carbon quantum dots (Mg/N doped CQDs) were prepared by hydrothermal method. Then Zn₄In₂S₇ series catalysts with different loadings (0, 0.3, 0.6, 1.2 wt %) of Mg/N doped CQDs (denoted as ZIS 350 °C, ZIS-3 350 °C, ZIS-6 350 °C, ZIS-12 350 °C) were constructed based on condensation reflux and inert gas calcination method. The catalyst possesses highly efficient visible light-catalyzed depolymerization of sodium lignosulfonate (SLS), an industrial waste material. From the BET curve, the specific surface area of ZIS-6 350 °C was the largest. The composite of Mg/N doped CQDs reduced the band gap of Zn₄In₂S₇ while promoting the separation and transfer of photogenerated electrons/holes, as confirmed by DRS, Mott-Schottky, transient photocurrent and EIS analyses. From the photocatalytic activity test, the photocatalytic depolymerization of lignin by ZIS-6 350 °C was increased by 21.2% compared with that of ZIS 350 °C, and the reactions all follow the pseudo first order kinetic model. A possible photocatalytic mechanism was proposed based on the active species capture experiments.

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This research introduces a groundbreaking bifunctional ionic catalyst, L-proline taurinate, synthesized in water using biodegradable materials, aligning with green chemistry principles. The structure of the synthesized catalyst was characterized using FT-IR, ¹H NMR, ¹³C NMR, and HRMS. The ionic nature of the catalyst was validated through density functional theory analysis. The catalyst demonstrated exceptional efficiency in the green synthesis of 2-amino-3-cyano-4H-pyrans and pyran-annulated heterocyclic scaffolds. A total of 23 compounds were synthesized in less than 10 min with excellent yields (86–98%), through the Knoevenagel-Michael-cyclization coupling reaction of aldehydes, 1,3-diketones, and malononitrile. The substrate versatility was demonstrated with substituted aromatic and heterocyclic aldehydes, along with 1,3-dicarbonyl compounds like dimedone, 1,3-cyclohexanedione, and 4-hydroxy-2H-chromen-2-one, as well as barbituric acid, 2-thiobarbituric acid, and 3-methyl-1-phenyl-2-pyrazoline-5-one. This robust protocol boasts features such as one-pot, single-step, three-component operations, easy catalyst separation and recycling potential, broad applicability to various substrates, and suitability for gram-scale production. This innovative approach represents a major stride in sustainable catalytic technology and green chemical procedures, paving the way for future advancements in eco-friendly synthesis techniques.

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In the pursuit of advanced catalytic materials, the synergistic integration of diverse components within a single platform has emerged as a transformative strategy. This paper unveils the synthesis of Cu nanoparticles immobilized on different magnetic metal–organic frameworks [NH₂-MIL-101(Fe), MIL-101(Fe) and MIL-101(Cr)]. The main focus of the present work is to study the effect of different metal ion and ligand of the framework on the catalytic activity of Cu nanoparticles. The catalytic potential of synthesized catalysts was compared for C–N coupling and reductive degradation of organic dyes. Among the three synthesized catalysts, Cu@NH₂-MIL-101(Fe)/Fe₃O₄ demonstrated high activity attributed to the synergistic interaction between NH₂-MIL-101(Fe) and Cu as well as due to higher immobilization of catalytically active Cu nanoparticles. The catalyst offered virtues like mild reaction conditions, magnetically separable, ligand-free conditions, high product yield; and turnover number in the range of 3.68 to 5.46. Moreover, the catalyst maintains its structural integrity, chemical properties and effective magnetic response after five catalytic cycles, as demonstrated by FTIR, XRD, XPS and VSM analysis of the recycled catalyst.

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The SnO₂/SnS₂ composite photocatalyst with mesoporous structure and Type-II heterojunction was successfully constructed, and sulfonamide antibiotics were used as the target degrader to explore the effects of mesoporous and heterojunction structures in SnO₂/SnS₂ on the photocatalytic degradation activity under visible light irradiation. The results show that SnO₂/SnS₂ obtained by hydrothermal reaction at 180 °C presents a unique flower-like spherical structure with high crystallinity and a particle size of about 5 μm, a large mesoporous pore size of 12.33 nm provided abundant ion or molecular channels and a relatively high specific surface area of 50 m²·g^− 1 provided abundant active sites. In addition, SnO₂/SnS₂ has low fluorescence intensity, indicating that the Type-II heterojunction structure formed promoted charge transfer, resulting in a higher separation efficiency of photo-generated charges (h⁺/e⁻). It is worth noting that SnO₂/SnS₂ has a strong light response at the wavelength of 200–800 nm, and degradation rate of SnO₂/SnS₂ was 1.7 times that of SnO₂ and 1.5 times that of SnS₂, after photocatalytic reaction time of 210 min, respectively. It is benefitting from that the Type-II heterojunction structure formed by the coupling of mesoporous SnO₂ and SnS₂ has a synergistic effect, which reduces the band gap and improves the photocatalytic activity. Furthermore, this study revealed that the reaction rate constant of SnO₂/SnS₂ photocatalytic degradation of sulfonamides increased with the increase of temperature, which belonged to the zero-order reaction with the apparent activation energy of (:1.201 times 10^{4})J·mol^− 1. Finally, the photocatalytic stability and reusability of SnO₂/SnS₂ were further confirmed through 5 cycles of photocatalytic degradation experiments. This study provides new insights for the development of heterojunction photocatalysts with mesoporous structure, and provide new ideas for photocatalytic technology in antibiotic degradation.

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Expired, non-edible forms of oats which are considered as trash have the potential to enable biodiesel production at larger scale without competing for any requirements. The process of producing biodiesel has been examined step-by-step, begining with the conversion of oat lipids to FAME. Using DME in a batch reactor, the SCE (super critical carbon dioxide extraction) method was used to extract lipids from oats. The fatty acid profile shows the abundance of C18 compounds from lipid extraction. Catalyst used for the biodiesel production was ZnO–Al₂O₃; in which varied loadings of copper was carried out. Utilizing XRD, FTIR, N₂ sorption, TPD, and SEM examination, the catalyst was characterized. A catalyst with an alcohol ratio of 2:10, a flow rate of 4 ml per hour, 300 mg of oats, and 15% of copper-loaded catalyst was found to be the most effective combination for converting lipids into biodiesel while also exhibiting high selectivity and yield. GCMS spectrum indicates the abundance of C18 fractions at 22.34 min with peak area of 53.69%. The kinetic study such as Arrhenius plot for pure biodiesel and biodiesel blend shows that pure biodiesel at constant temperature shows rate maximum. Engine analysis characteristics such as brake power, torque, BTE, CO, and NO emission data demonstrated the performance of pure biodiesel that was obtained in good yield from oat lipid.

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The catalytic removal of trace formaldehyde (HCHO) at ambient temperatures is crucial for improving indoor air quality, necessitating the use of monolithic catalysts over traditional powder forms for real-world applications. In this study, an aluminosilicate fiber-woven ceramic filter paper (CFP) was selected as the substrate, onto which a Mn₂O₃ catalyst was in situ coated via a combustion method utilizing Mn(NO₃)₂ as the oxidant and glycine as the fuel. The resulting monolithic Mn₂O₃/CFP catalyst was compared to a MnO₂/CFP catalyst, prepared by direct decomposition of Mn(NO₃)₂ on the same substrate. The Mn₂O₃/CFP catalyst exhibited superior characteristics for HCHO oxidation, including a more porous architecture, higher redox capability, and an abundance of surface-active oxygen species with enhanced mobility of surface lattice oxygen. These features enabled the Mn₂O₃/CFP catalyst to achieve significantly higher HCHO conversion at room temperature (90%) compared to the MnO₂/CFP catalyst (21%). Additionally, in a durability test carried out in a mode of dynamic flow at room temperature, the Mn₂O₃/CFP catalyst maintained a high HCHO conversion rate of 66% over 11 days, demonstrating its potential for practical indoor air purification applications.

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The escalating global energy demand, predominantly satisfied by fossil fuels, has led to severe environmental repercussions, including the emission of harmful pollutants and the depletion of non-renewable resources. This study explores the synthesis of green heterogeneous ZnO/SiO₂ derived from date leaves ash (DLA) as an innovative catalyst for biodiesel production, specifically using waste cooking oil (WCO) as feedstock. WCO, a prevalent byproduct in the food industry, poses significant environmental challenges, yet it offers a valuable opportunity for sustainable energy generation. The transesterification process in this study highlights additional techniques to improve the product by focusing on the intermediate species, which is essential to enhance the conversion of triglycerides in WCO to biodiesel, on the other hand enhanced by the application of the synthesized catalyst, which exhibits superior catalytic activity and stability. The research also highlights the advantages of using heterogeneous catalysts over traditional homogeneous catalysts, including ease of separation, reusability, and reduced environmental impact. The findings demonstrate that the DLA-derived ZnO/SiO₂ catalyst not only improves biodiesel yield but also contributes to waste management by repurposing WCO, thereby mitigating its adverse effects on public health and the environment. This work underscores the potential of green chemistry in developing efficient, eco-friendly catalysts that can significantly advance the biodiesel industry. This research advocates the integration of sustainable practices in energy production, emphasizing the importance of renewable resources in addressing the pressing challenges of energy sustainability and environmental protection. Ultimately, several highlights of this research have led to over 95% of WCO being converted to biodiesel using ZnO/SiO₂-30 at 60 °C.

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The bifunctional catalyst Ru/Hβ was prepared by equal volume impregnation method and applied to the study of the kinetics of benzene hydroalkylation reaction. The reaction order of 1 for benzene and 1.94 for H₂ (({P}_{{H}_{2}}le 3text{ MPa})) was obtained by fitting the kinetic experimental data first. Then a kinetic model conforming to the Eley–Rideal (E–R) mechanism was developed based on the types of adsorbates on different active centers of the solid catalyst, and the main mechanism was that the benzene in the adsorbed state was partially hydrogenated to produce cyclohexene, which was not desorbed from the active centers. Some of it was further hydrogenated to produce cyclohexane, and some was alkylated with benzene in the bulk phase to produce cyclohexylbenzene. The reaction rate control step was the alkylation of benzene and cyclohexene. The model parameters were calculated using a genetic algorithm. The model was tested to be able to describe the reaction mechanism of benzene hydroalkylation well and to provide guidance for process optimization.

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Benzene hydroalkylation is a key starting step in the process of preparing phenol by the cyclohexylbenzene method instead of HOCK method, and there is a great lack of related kinetic studies. In this paper, the bifunctional catalyst Ru/Hβ was prepared and applied to the study of the kinetics of benzene hydroalkylation reaction. A kinetic model conforming to the Eley-Rideal (E-R) mechanism was developed. The model parameters were calculated using a genetic algorithm. The model was tested to be able to describe the reaction mechanism of benzene hydroalkylation well and to provide guidance for process optimization.

The La nanorod and cobalt-manganese spinel were synthesised by an improved sol–gel technique for the selective oxidation of alcohols. The active sites of the catalyst were demonstrated using parameters and a recycling study. Moreover, the catalyst was characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectra, X-ray diffraction, and surface analysis to examine the impact of La addition on the structural and morphological characteristics of CoMn₂O₄. La is introduced into CoMn₂O₄, which decreases the activation energy; therefore, CoMn_2-XLa_XO₄ selectively oxidizes alcohol at lower temperatures. Higher benzyl alcohol to benzaldehyde conversion was observed for the CoMn_1.96La_0.04O₄ catalyst. The catalyst was further also examined for the selective oxidation of other alcohols. The various commercially important substrates like 2-bromo benzyl alcohol, furfuryl alcohol, etc. undergo selective oxidation using a catalyst was also been investigated. The mechanistic aspects of the catalyst with active sites have been explained using Raman and ATR-FTIR adsorption study.

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