Magnetically recoverable AuPd nanoparticles prepared by a coordination capture method as a reusable catalyst for green oxidation of benzyl alcohol

Abstract

AuPd nanoparticles (AuPd NPs) have received considerable attention because of their importance as catalysts in selective aerobic oxidations; however, improved synthetic methods for making them reusable catalysts are necessary. Here, we present the preparation of magnetically recoverable AuPd NPs by immobilizing pre-synthesized PVA-stabilized AuPd NPs onto magnetic supports. The immobilization method is based on the functionalization of the support with strong coordinating ligands, such as amino and thiol, for the attachment of AuPd NPs containing weak coordinating groups. We were able to increase the metal loading by a coordination capture method with functionalized supports, but the ligands grafted on the support surface affected the catalytic activity of AuPd NPs. Moreover, the amino groups provided stabilization in solution, which made the catalyst separation after reaction difficult. Finally, we obtained highly active and recyclable catalysts by removing the functional groups by a thermal treatment. Negligible metal leaching and catalyst recycling in successive reactions are important features of the new catalytic system.