Palladium nanoparticles doped on hybrid magnetic biochar: An efficient andheterogeneous catalyst for Suzuki coupling reaction

Nowadays, catalysts play an important and crucial role in most modern processes in thepharmaceutical, agrochemical, food, petrochemical, and even automobile industries. However, someweaknesses such as the remarkable decrease in catalytic performance due to particle agglomeration,instability originating from high surface energy, and more importantly difficulties in separation and recyclingseverely limit practical and cost-effective applications of homogenous catalysts such as, Pd catalysts. On ofthe best way to control and stabilize the Pd nanoparticles is dispersing small-size Pd nanoparticles onappropriate supporting inorganic materials, such a carbon materials and magnetic nanoparticles. In particular,biochar is one of the best candidate for catalytic activity due to their unique properties such as high surfacearea [۱]. Moreover, magnetic nanoparticles can lead to the formation of separable magnetic catalysts that canbe easily recovered using an external magnet, making chemical synthesis cleaner and more economical.Among these, hollow sphere material is a good magnetic substrate for immobilizing palladium nanoparticles[۲]. Mostly, to improve the recovery and the catalytic activity of both, it can hybridized together or with othermaterials. The results confirmed that hybridization of biochar and h-Fe۲O۳ can be considered as a solution forcircumventing the drawbacks of these two carbon materials. The Suzuki coupling reaction is a type of couplingreaction in which a boronic acid and an aryl halide are coupled together in the presence of a palladium catalyst.Palladium (Pd)-based catalysts are essential to drive high-performance Suzuki coupling reactions [۳].Following the work of our research group [۴,۵], herein, the catalytic activity of palladium-containing hybridmagnetic biochar catalyst was described. This palladated magnetic-hybrid system, h-Fe۲O۳@SiO۲–biochar@Pd, as a heterogeneous catalyst was synthesized through covalently hybridization of h-Fe۲O۳@SiO۲–NH۲ with biochar-Cl that prepared from wild eggplant followed by the incorporation of Pd NPs.The catalytic activity of h-Fe۲O۳@SiO۲–biochar@Pd was investigated for ligand and copper-free Suzukicoupling reaction,The nanocatalyst has been found to be an efficient and magnetically separableheterogeneous catalyst for Suzuki–Miyaura coupling reaction at a low concentration (۰.۰۳g h-Fe۲O۳@SiO۲–biochar@Pd) under mild reaction conditions (۷۵-۱۰۰%), Scheme ۱. Finally, the recyclability of this catalystwas also studied. The catalyst could be successfully removed from the reaction mixture by using an externalmagnet and also recycled for several consecutive reaction times with slight loss of the catalytic activity.

Keywords:

suzuki coupling , Magnetic Nanoparticle , Biochar