جستجوی مقالات مرتبط با کلیدواژه « نانوکاتالیزگر » در نشریات گروه « شیمی »

Pyrazolophthalazines and their derivatives are known as a substance with diverse chemical and biological activity. These compounds have various medicinal properties such as anti-bacterial, anti-viral, anti-coagulant and anti-cancer. In this research synthesis of Pyrazolo-phthalazine derivatives by reaction of aromatic aldehyde derivatives, Phthalic hydrazide and malononitrile in the presence of Hercynite as nano-catalyst were studied and the products were obtained in 45-90 minutes with yield of 90-97%. The structure of Hercynite nanocatalyst was investigated using FT-IR and SEM methods and X-ray diffraction pattern. The results of the morphology of the nanocatalyst surface show that the nanoparticles are spherical and the size of the particles is between 49-80 nm. Investigating the magnetic property of the catalyst with VSM analysis shows the favorable magnetic property of Hercynite nanocatalyst for its separation with an external magnetic field. Easy operation, high efficiency, reuse of the catalyst for several times, short reaction time and easy separation of the catalyst using an external magnet are the most important advantages of the presented method.

In this project, based on previous findings, first the magnetic nanoparticles were coated with silicon dioxide particles by core-shell method and from reaction with 3-chloropropyl triethoxy silane and then with organic ligand thiocarbohydrazide (Fe3O4@SiO2-TCH) was functionalized. The Cu ions were then stabilized on magnetic silicate surface. The structure of the prepared nanoparticles as a magnetic organic-metal hybrid was investigated and confirmed using FT-IR, FESEM, EDX, XRD, TGA, VSM and BET instrumental methods. Next, its catalytic activity in the synthesis of a number of 4-aryl-2-amino chromenes was investigated by the three-component condensational reaction of aldehydes, malononitrile and dimedone. The advantages of this method include cheap, safe and reusability of nanocatalyst, easy separation of heterogeneous catalyst from the reaction medium, short reaction time, high efficiency, easy and fast separation of the product and use of non-toxic water solvent, which makes this method in simplicity, be in the scope of "green chemistry".

Today, biodiesel is being produced and consumed around the world as one of the main sources for replacing fossil fuels. In current research, cobalt doped zinc oxide was used as nanocatalyst to produce biodiesel from soybean oil by transesterification reaction. The nanocatalysts used were first prepared by microwave method and identified by X-ray diffraction (XRD), scanning electron microscopy (SEM) and x-ray energy dispersive spectroscopy (EDS). In the next step, the prepared catalysts were used in the reaction of biodiesel production from soybean oil. The produced biodiesel was characterized using nuclear magnetic resonance spectroscopy (NMR) and gas chromatography-mass spectroscopy (GC-MS). Optimal reaction conditions of biodiesel production with cobalt doped zinc oxide nanocatalyst obtained, at 3 h, temperature 60 ˚C, catalyst concentration 3% by weight, and molar ratio of oil to methanol 1 to 41 resulted in 98% efficiency. In another part of this research, microwave radiation with a power of 250 W was used as a source of energy in the biodiesel production reaction which in the presence of 4% by weight of catalyst and molar ratio of oil to methanol 1 to 20 resulted in 91% efficiency in 180 s.

In this study, we present a versatile and easy procedure for modifying a ferrite nanoparticle so step by step. A new nanocatalyst was prepared via CoII immobilized onto an aminated ferrite nanoparticles (Fe3O4@HT@AEPH2-CoII). The nanocatalyst was fully characterized by FT-IR, EDX, FE-SEM, TGA, XRD,, EDS and VSM analyses. In the preparation of 14 aryl-14H-dibenzo[a.j] xanthenes, the corresponding nanocatalyst shown great catalytic activity. The reaction contains expeditious reusable catalyst (Fe3O4@AEPH2-CoII) that promotes condensation between aromatic aldehydes and β-naphthol. Also, the environmentally toxic solvents were eliminated. A significant improvement in the synthetic efficacy (95%, yield) was obtained by this new sustainable and eco-friendly protocol as well as high purity. The current procedure as a green protocol offers benefits including a simple operational procedure, an excellent yield of products, mild reaction conditions, minimum chemical wastes, short reaction time, and easy catalyst synthesis. Without any significant reduction in the catalytic performance, up to five recyclability cycles of the catalyst were obtained. The optimization results suggest that the best condition in the preparation of xanthene derivatives is 0.003 gr of the Fe3O4@HT@AEPH2- CoII nano catalyst under solvent free at 90 ◦C. The proposed protocol could be applied on a wider scope of the substrate (i.e., electron-deficient and electron-rich).

In this study, the SBA-15 nanoparticles were functionalized with (3-Chloropropyl) triethoxysilane and then with the thiocarbohydrazide organic ligand (TCH@SBA-15). Nickel acetate ions were then stabilized on silicate nanosupport (Ni/TCH@SBA-15). The prepared nanocomposite as an organic-metal hybrid was identified using FT-IR, SEM, TEM, XRD, EDAX and BET analysis. The Ni/TCH@SBA-15 nanoparticles were used as efficient and heterogeneous nanocatalysts for the easy and effective synthesis of 2-aryl benzimidazoles. In this catalytic process, benzimidazole heterocycles were obtained from the condensation reaction of different 1,2-phenylenediamine derivatives and various aromatic aldehydes in solvent-free conditions in excellent yields. This green approach can provide a new route for the preparation of all kinds of organic heterocycles.

In this research, nano-silica coated with phosphotangestic acid was used as a new, effective and heterogeneous high-selectivity catalyst for the diastereoselective synthesis of trans-2,3-dihydrofuran during, multi-component one-pot and solventless reaction. In this reaction, the in-situ production and condensation of pyridinium bromide ylide are carried out with benzaldehyde and 4-hydroxy-coumarin derivatives. The size and shape of the catalyst were studied using detection methods such as scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FT-IR). Also, the BET analysis of this nano-catalyst showed a high surface area, which could be a factor in the good performance of this nano-catalyst. An induction coupled plasma analysis also confirmed the ability to recover of this nanocatalist.The reaction products were evaluated using FT-IR spectroscopy and melting point determination. High efficiency, short reaction time, solventless conditions and easy product separation method are the future advantages of this research.

In this study, the effects of two parameters including reaction time and catalyst loading on the decolorization of methyl orange (MO) dye in Photo-Fenton process by synthesized vanadium ferrite nanocatalyst under UV irradiation have been studied. In order to optimize the decolorization efficiency, response surface methodology (RSM) based on central composite rotatable design (CCRD) was employed. Optimum condition for decolorization of methyl orange solution with concentration of 25mg/L was obtained at 30 min and catalyst loading of 0.08g. The results show that vanadium ferrite nanocatalyst presents excellent photo-Fenton activity on the degradation of MO under UV irradiation. At the optimum conditions, a decolorization of more than 99.1% can be obtained. Therefore, degradation of dyes and treatment of dye-containing industrial effluents can be efficiently performed by Photo-Fenton process using vanadium ferrite nanocatalyst.