Iranian Journal of Catalysis
Volume:12 Issue: 3, Summer 2022

Over the past half-decade, the functionalized Fe3O4 nanoparticles have been applied to organic synthesis as heterogeneous nanocatalysts. Due to the magnetic properties, the functionalized Fe3O4 nanoparticles have been preferred over other catalytic systems. In addition, the unique physical, chemical, and magnetic field properties of Fe3O4 nanoparticles have led to the development of them for efficient organic synthesis as heterogeneous catalytic systems. Over the past half-decade, all the researchers tried to design and develop different functionalized Fe3O4 nanoparticles to perform the organic transformation. In this mini-review, different methodologies for the synthesis of six-membered compounds (heterocyclic compounds) containing nitrogen catalyzed by functionalized Fe3O4 nanoparticles have been reviewed. This short review aims to comprehensively investigate the use of functionalized Fe3O4 nanoparticles in the synthesis of six-membered compounds (heterocyclic compounds) containing nitrogen with emphasis on their reusability of the catalysts and magnetic field of them in separation from the organic reaction medium.

Single-atom catalysts have recently received much scientific attraction as sustainable catalysts due to their greater activity and selectivity arising from the uniform distribution, electronic properties, and quantum mechanical interactions at the nanoscale of single atoms coupled with interactions at the metal-support interfaces. Carbon-based materials are an excellent support material for single-atom catalysts owing to their inherent properties such as adjustable pore size, high surface area to volume ratio, and ease of surface functionalization. The interactions at the single atom-carbon support interfaces give rise to the extraordinary catalytic activity in carbon-based single metal catalysts thus opening doors for a wide range of sustainable applications. This review focuses on the evolution of carbon-based single-atom catalysis covering different types of carbon substrates, usage of different single atoms with special attention to transition metals, and its wide range of applications including photocatalysis, organic catalysis, and electrocatalysis followed by the future perspectives on carbon-based single-atom catalysts.

Fe-doped TiO2 nanoparticles were successfully synthesized by the coprecipitation method. TiO2 was doped with a different molar ratio of iron amounts, namely 0.1% and 0.2%. An undoped TiO2 was also prepared for comparison. X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-visible diffuse reflectance spectroscopy techniques were used to characterize the as-synthesized nanoparticles. The XRD spectra revealed that the photocatalysts were mostly in a well-crystallized anatase phase. Optical properties of the powders shifted from UV to the beginning of the visible light (Vis-L) region. Absorption edge wavelengths between 392 and 380 nm were obtained for the Fe-doped TiO2 and TiO2-P25, corresponding to band gap energies between 3.17 and 3.26 eV. TEM images showed homogeneity with a certain degree of agglomeration for all the samples. The photocatalytic efficiency of the as-synthesized Fe-doped TiO2 nanoparticles was performed using azo dye methyl orange (MO) in an aqueous solution under Vis-L irradiation. The photocatalytic results showed that Fe-doped TiO2 nanoparticles effectively degrade MO under Vis-L excitation and follow pseudo-first order kinetics. Besides, kinetic comparison showed that pure TiO2 is less efficient than 0.1% and 0.2% Fe-doped TiO2 because they exhibit unequaled efficiency. Moreover, the photocatalyst at 0.2% Fe-doped TiO2 molar ratio revealed the highest photocatalytic efficiency, which was 4.2 times higher compared to pure TiO2. Different amounts of Fe induced different increases in the apparent first-order rate constant of the photocatalytic process.

In this investigation, a fluidized bed photocatalytic reaction system was designed to eliminate emerging contaminants: acetaminophen and pyridine in water. Titanium dioxide (TiO2) doped with aluminum (Al3+) using the photo-deposition technique was used as a catalyst and supported on alumina beads (Al2O3). The catalyst´s doping was carried out by photo deposition with aluminum particles. The reactor, which is a quartz vessel with a capacity of 500 mL, where aluminum pearl, was previously impregnated with titanium oxide and calcined at 550 °C. The reactor feeding was carried out using a pump at a flow of 0.5 L/min; two lamps of UV light with 365 nm were used. The synthesized catalyst was characterized through Energy-dispersive X-ray analysis (EDX), Transmission Electron Microscopy (TEM), and X-ray diffraction (XRD) techniques, showing adequate impregnation of aluminum in the formed compound. Photoactivity analysis of the catalyst was performed at different contaminant concentrations, from 5-40 ppm for acetaminophen and 5-60 ppm for pyridine. Mineralization of more than 85% acetaminophen and 70 % pyridine was achieved after 300 min of UV illumination. The results demonstrate that using this photocatalytic arrangement as a decontamination technique for the pollutants such as acetaminophen and pyridine is feasible.

In this study, we discuss the wet chemical synthesis and experimental analysis of zinc doped Gd2O3(Gd2-xZnxO3-δ) nanoparticles where, x=0, 0.1, 0.2, 0.3, 0.4, and 0.5. The cubic crystalline structure is derived from XRD results and the existence of metal-oxide bond has been confirmed from FTIR studies. According to SEM and PSA analysis, the produced nanoparticles are found to be of nano size. The EDX data verified the presence of Gd, Zn, and O in the samples. Based on UV-visible spectroscopy, the band gap and λmax values were computed. In an aqueous medium and under UV light irradiation, the photodegradation of Rhodamine B over Zn doped Gd2O3 nanoparticles was studied. It was observed that Gd1.50Zn0.50O3-δ has exhibited 82% of photo-degradation of the dye solution which further increased to 96% because of increasing the catalyst loading. The effect of pH and the concentration of the dye are also reported. According to the kinetic analysis, the photocatalysis process followed a pseudo-first-order kinetic model. A radical scavenger technique was used to further examine and identify the function of photoactive species.

We studied the reaction in which carbon monoxide is converted to hydrocarbons, and investigated the behaviors and the combination system of catalysts exchanged with platinum and ammonium ions. Experiments were conducted at 1.2 MPa, 523K, and CO/H2=1 ratio. The structure and the texture of the catalysts, assessed by XRD, BET/BJH, and SEM, exhibited a microporosity for ZSM-5/11 and a micro/mesoporosity for AlMCM-41, which implies a direct effect on the catalytic properties of these materials. The conversions obtained were 60%, 55%, and 50% for Ptn+/H+-catalysts, Ptn+-catalysts, and H+-catalysts respectively. Such conversions could be attributed to the good acidity resulting from the simultaneous presence of Ptn+/H+ at different oxidation states of platinum, which was revealed by XANES PtLIII analysis, and their uniform dispersion within the inner surface and its grain size average conducted by the titration of adsorbed H2-O2. FTIR analysis showed a better distribution of acid sites for bi-exchanged catalysts over mono-exchanged ones, which resulted in a good catalytic activity. These results suggest a strong correlation between the high selectivity of light hydrocarbon products, the ions, and the catalyst types. These differences depended mainly on the facility of forming different products, such as n/iso-alkanes and alkenes. Skeletal isomerization was the main transformation observed on exchanged catalysts, particularly those with Ptn+/H+ ions. A deactivation process of catalysts, versus time-on-stream, begins after 70 minutes, especially for combined exchanged materials.

In this study, the electrochemical determination of oxazepam in plasma samples was studied. The composite of graphene oxide/boron (B-RGO) was synthesized via the hydrothermal method and it was cast on the glassy carbon electrode (GCE). The polyaspartic acid (poly(ASP)) was deposited on the B-RGO by electropolymerization to prepare the modified electrode named B-RGO/ poly(ASP)|GCE. The B-RGO and B-RGO/poly ASP were characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Electrochemical studies were performed by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and differential pulse voltammetry (DPV) methods. The experimental parameters affecting the reduction of oxazepam such as pH, preconcentration time, scan rate and other analysis conditions, and instrumental parameters were optimized. Under the optimal conditions, the linear range was obtained from 0.001 to 800 μM with a correlation coefficient of 0.998. The repeatability of the method for the electrode to electrode and one electrode were 4.3% and 4.9%, respectively. The limit of detection (LOD) of 0.3 nM and the limit of quantitation (LOQ) of 1 nM were obtained. The high efficiency of the developed electrode in the determination of oxazepam in the plasma sample was proved by using acceptable results and satisfactory relative recovery percentage (>90%). Based on our calculation, the heterogeneous electron transfer rate constant (ks) was 1.92 s-1. The interaction between oxazepam and modifier was single-layer and multi-layer adsorption, respectively in low and high concentrations.

In this research work, Nano-SiO2/Taurine was synthesized and characterized by FT-IR, energy dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), X-ray diffraction patterns (XRD) ,Thermogravimetric analysis (TGA) and MAP analysis. Nano-SiO2/Taurine has considerable benefits such as simple preparation protocol, simple handling, high acidic property, reusability and high stability. Nano-SiO2/Taurine was used as a catalyst for the synthesis of hexahydroquinolines by the reaction of ethyl acetoacetate, dimedone and ammonium acetate with various aldehydes. These reactions were carried out under solvent-free conditions at 85 °C. The present protocol is simple, eco-friendly and efficient. The hexahydroquinolines were produced at high yields and short reaction times.

In this study, two different methods were described for the synthesis of 2-(aryl)-3-((2-oxo-2-(2-oxo-2H-chromen-3-yl)ethyl)amino)imidazolidin-4-one derivatives under microwave irradiation. The first method was step by step method. In step by step method, 3-(2-hydrazinylacetyl)-2H-chromen-2-one and aromatic aldehydes in 1 mL of absolute ethanol were irradiated with appropriate power within 3-10 min to obtain imine products. Then, the imine products were isolated and reacted with glycine to produce the 2-(aryl)-3-((2-oxo-2-(2-oxo-2H-chromen-3-yl)ethyl)amino)imidazolidin-4-one under microwave irradiation. In the one-pot method, the graphene oxide nanosheets were applied as heterogeneous catalysts. Hence, the graphene oxide nanosheets were synthesized based on Hummer’s method. The catalyst was characterized by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and X-ray diffraction (XRD) techniques. Then, 3-(2-hydrazinylacetyl)-2H-chromen-2-one, glycine, and aromatic aldehydes were irradiated using microwave irradiation in the presence of 0.5 mol% of graphene oxide nanosheets in ethanol. The prepared catalyst showed superior reusability for seven catalytic cycles. Our results showed that the one-pot method was better than the step by step method.

Modification of sodium montmorillonite was conducted using zirconium phosphate. The effect of a series of phosphate precursors such as dihydrogen phosphate, diammonium hydrogen phosphate, and sodium phosphate was observed. The catalyst was used in the conversion of methanol dimethyl ether using 1 g of catalyst at a temperature range of 150-350 ˚C with a Liquid Hourly Space Velocity (LHSV) monitored to 2.54 h−1 and N2 as carrier gas. The product was analyzed directly with a reactor system connected to gas chromatography. The X-ray diffraction (XRD), Scanning electron microscope-energy dispersive X-ray (SEM-EDX), N2 adsorption-desorption, and Temperature-programmed desorption of ammonia (NH3-TPD) were utilized to characterize the catalyst. The characterization showed that the modified sodium montmorillonite-zirconium phosphate was successfully synthesized. The study showed that modified montmorillonite using zirconium phosphate significantly increased the catalytic activity of sodium montmorillonite by providing medium and strong acid sites also increased the surface area. The modified sodium montmorillonite-zirconium phosphate from dihydrogen phosphate precursor exhibited the highest catalytic activity with the methanol conversion of 96.76%, dimethyl ether selectivity of 96.8%, and dimethyl ether yield of 93.67%, whereas the modified sodium montmorillonite-zirconium phosphate from diammonium hydrogen phosphate showed good stability towards methanol conversion.