Preparation and characterization of a novel organic–inorganic hybrid nanostructure: application in synthesis of spirocompounds

Zn complexed on hybrid manganese doped cobalt ferrite nanoparticles covered by silica as a catalyst in the synthesis of 2-amino-4H-pyran and N- arylquinoline derivatives

In the present work, Zn complexed on hybrid manganese doped cobalt ferrite nanoparticles covered by silica were synthesized. These MNPs were characterized using different techniques including Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction analysis (XRD), Field emission-scanning electron micro-scope (FE-SEM), Energy-dispersive X-ray spectroscopy (EDS), Vibration sample magnetometer (VSM), Inductively coupled plasma atomic emission spectroscopy (ICP), Zeta potential and Thermogravimetric analysis (TGA). FE-SEM Images showed uniform spherical shape with rough surfaces and an aggregation in structure of MNPs. A decrease in Ms is visible in VSM analysis due to the increase in particle diameter as a result of loading the organic coating on the surface of the magnetic nanoparticles. According to TGA analysis, the synthesized MNPs have good stability up to 125 °C. The ICP analysis indicates the presence of 0.13 mmol/g zinc on the surface of loaded MNPs. The effect of these prepared MNPs as a catalyst was studied in the synthesis of 2-amino-4H-pyran and N- arylquinoline derivatives. This method provides excellent yield of products with short reaction time, simple purification and easy separation of the catalyst. Furthermore, the reusability of the catalyst during five periods was not associated with a significant decrease in its activity.

Deep oxidative desulfurization of simulated and real gas oils by NiFe2O4@SiO2-DETA@POM as a retrievable hybrid nanocatalyst

Magnetic nanoparticles surrounded with a silica shell are useful materials to immobilize active agents on their surface. Here, a heteropolyacid-functionalized hybrid nanomaterial (NiFe₂O₄@SiO₂-DETA@POM) was prepared and characterized by X-ray powder diffraction patterns (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA/DTG), vibrating sample magnetometer (VSM), the field emission scanning electron microscopy (FE-SEM), and the electron-dispersive X-ray spectroscopy (EDS). The synthesized hybrid nanostructure was used as a solid nanocatalyst in oxidative desulfurization (ODS) of real fuel and simulated gasoline samples. The ODS process of benzothiophene (BT) and dibenzothiophene (DBT) as model compounds in the presence of NiFe₂O₄@SiO₂-DETA@POM and by using urea-hydrogen peroxide/acetic acid as a safer oxidizing agent was investigated. A good result was obtained by removing 97% of benzothiophene and 98% of dibenzothiophene. Also, 96% of the sulfur compounds were eliminated when the ODS process was tested on a real crude oil sample (600 ppm) under an optimized dosage of nanocatalyst, urea-hydrogen peroxide/acetic acid (0.1 g, 1 g/4 ml) at 50 ºC for 60 min. NiFe₂O₄@SiO₂-DETA@POM could be recycled for five consecutive oxidation runs without significant deterioration in its catalytic activity. The UHP's safety and efficiency as an oxidant, high removal efficacy, short transformation times, easy workup procedure, catalyst reusability, simple separation of nanocatalyst, green conditions, and environmental compatibility and sustainability. The obtained results prove that NiFe₂O₄@SiO₂-DETA@POM is a suitable and efficient hybrid catalyst for the oxidative desulfurization of simulated and real fuels.