Fabrication of Palladium Nanoparticles Supported on Natural Volcanic Tuff/Fe3O4 and Its Catalytic Role in Microwave-Assisted Suzuki–Miyaura Coupling Reactions

Abstract

Natural minerals have a huge potential as stabilizers in the catalytic systems due to their high mechanical durability, porous surface, non-toxicity and abundance in nature. This study aims to the development of a magnetically retrievable, heterogeneous palladium catalytic system derived from volcanic tuff (VT), an abundant form of zeolite, for Suzuki–Miyaura coupling (SMC) reactions. For this purpose, a new catalyst support was designed by loading volcanic tuff with Fe3O4 (VT/Fe3O4) and palladium nanoparticles were prepared on VT/Fe3O4 via wet chemical reduction method (Pd NPs@VT/Fe3O4). Then, Pd NPs@VT/Fe3O4 was evaluated as a heterogeneous catalyst in the microwave-assisted production of biaryl via SMC reactions. Pd NPs@VT/Fe3O4 efficiently coupled various substituted aryl iodides, bromides and chlorides in a very short reaction time, solvent-free media and in an air environment. Catalytic tests indicated that Pd NPs@VT/Fe3O4 converted aryl halides into desired biaryls with a high yield up to 99%. Moreover, it was showed that Pd NPs@VT/Fe3O4 retained its stability and catalytic performance by producing 92% yield after eight successive cycles. This study demonstrated that VT can be a good alternative support alongside other known supports such as biopolymers, carbon and silica based materials and it can be utilized for the synthesis of different catalysts.