Authors: S.C. Tsanga, K. Tamb, X. Gaoa, C.H. Yua, C.M.Y. Yeunga and K.K.M. Yua
Affilation: University of Reading, United Kingdom
Pages: 615 - 618
Keywords: nanocatalyst, magnetic, separation and fine chemicals, green catalysis
Separation of nanosize catalyst from product in liquid phase has been a major problem in industry. Thus the facilitated separation of a small magnetic body carrying catalytically active species is of a tremendous interest however; the stability of the magnetic body remains a key issue. We report new syntheses of silica and carbon encapsulated magnetic nanosize particles (10-30 nm) as magnetic separable carriers in large quantities based on simple synthetic techniques. The major advantage of using nano-size magnetic particles as catalyst carriers is that they display an excellent mass transfer coefficient (high surface area to volume ratio) comparable to soluble species but can still be easily separated from liquid using magnetic interaction with an external applied inhomogeneous magnetic field. It is shown that the external coating surfaces (silica and carbon) can isolate and protect the magnetic core from destructive reactions with the environment where a wide range of conditions for fine chemical catalysis can be made possible. The functionalized surfaces could also offer anchoring sites for the immobilization of catalytically active species (nano-metal particulates, homogeneous catalysts and enzymes). With such small magnetic catalyst bodies, the advantages of homogeneous (or colloidal) and heterogeneous catalysis can be combined. Apart from catalytic applications, other exciting applications of the coated nanometer-sized magnetic particles are envisaged. Reference: 1. S.C.Tsang, V. Caps, I. Paraskevas, D. Chadwick, D. Thompsett, Angrew. Chem. Int. Ed. Engl. 43, 2004, 5645-5649. 2. X. Gao, K.M.K. Yu, K. Tam, S.C. Tsang, Chem. Commun., 24, 2003, 2998-2999. 3. K. M. K. Yu, D. Thompsett, S. C. Tsang, Chem. Commun. 2003, 1522 – 1523.