XPS and structural studies of FeO-PTMS-NAS@Cu as a novel magnetic natural asphalt base network and recoverable nanocatalyst for the synthesis of biaryl compounds.

In this research, natural asphalt as a mineral carbonuous material was converted to sodium natural asphalt sulfonate (Na-NAS) and, then, was linked to FeO MNPs in order to synthesize the magnetic nanocatalyst. Afterwards, Cupper (I) and Cu (II) was grafted on FeO-PTMS-NAS. Moreover, it is worth mentioning that the synthesized the novel magnetic nanocatalyst (FeO-PTMS-NAS@Cu) was successfully used in Suzuki and Stille coupling reactions. The FeO-PTMS-NAS@Cu MNPs were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), inductively coupled plasma (ICP), BET and X-ray photoelectron spectroscopy (XPS) analysis. Besides, sulfonation of natural asphalt, magnetization of catalyst, grafting of Cu (I) and Cu (II) to NAS and catalyst formation were investigated and proved carefully. This nanocatalyst can be comfortably separated from the reaction medium through an external magnetic field and can also be recovered and reused, while maintaining its catalytic activity.