Highly active and stable supported Pd catalysts on ionic liquid-functionalized SBA-15 for Suzuki–Miyaura cross-coupling and transfer hydrogenation reactions

Abstract

Highly dispersed palladium nanoparticles were synthesized in the presence of immobilized ionic liquid on mesoporous silica SBA-15. PdNPs(2.4 nm)_me-Im@SBA-15 catalyst was prepared by the reduction using NaBH4 as the reducing agent with controlled feed rate and has been investigated as ligand-free catalyst for Suzuki–Miyaura cross-coupling reaction at room temperature in aqueous solution under air. PdNPs catalyst was also prepared in situ from PdCl4_me-Im@SBA-15 during the reaction and demonstrated high activity and stability towards nitrobenzene hydrogenation at high temperature. Both catalysts were reusable at least for four recycle processes without significant loss in activity with simple procedure. The catalysts were characterized by TEM, EXAFS, FTIR and XPS. Keywords: Palladium nanoparticle, Ionic liquid, SBA-15, Suzuki–Miyaura cross-coupling, Hydrogenation