Magnetically Retrievable Palladium/Maghemite Nanocomposite Catalysts Prepared by Sonochemical Reduction Method
Graduate School of Science and Technology, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521(Received June 6, 2008; CL-080571; E-mail: mizukosi@imr.tohoku.ac.jp)Nanocomposite catalysts, consisting of Pd and magneticmaghemite, prepared by sonochemical reduction methodshowed high catalytic activities for the reduction of nitroben-zene. The used catalysts could be readily retrieved by magnetsand be employed for further repetitive tests and veriﬁed thedurability of the catalytic performance.The demands of noble metals, which are indispensable forIT industries and environmental protections such as automobilecatalysts, have been extensively increasing. In uses of thesenoble metals, it is important to develop sustainable processeslightening the burdens on the environment.It is a general strategy to fabricate nanosized noble metalsto enhance the catalytic activities. The fatal drawback of thenanoparticles is the diﬃculty in retrieving them from the reac-tionsystem.Further,remainingnanoparticlesinthereactionsys-tem contaminate the reaction products. From the view point ofrecycle of noble metals, it is necessary to establish the eﬀectivemethodology forretrieving thenoble metal as reusable catalysts.In this study, we demonstrate the magnetically retrievablenovel nanocatalysts consisting of Pd and magnetic maghemite( -Fe