Preparation And Characterization Of The Magnetic Nano-size Solid Acid Catalyst

A series of novel magnetic nano-size solid acid catalysts were prepared by enwrapping the magnetic core of Fe3O4 with solid acid or solid superacid. The new catalysts were characterized by techniques such as XRD, XPS, TEM and specific surface area measurements, etc. The new catalyst showed high catalytic activities for esterification of acetic acid with butyric mellow. All of magnetic nano-size solid acid catalysts can be separated from the reaction system by magnetism.The strongest magnetic cores of nano-size Fe3O4 were synthesized with a proper feeding ratio of Fe2+/Fe3+ and a suitable concentration of NaOH solution. Then the solid acids ZrO2 was deposited over the magnetic cores to form ZrO2/Fe3O4. The effects of preparation conditions on the particle size, magnetic and catalytic properties were investigated. The catalyst was then treated with sulfuric acid and calcined at a high temperature to form the strong solid superacid SO42-ZrO2/Fe3C>4 with magnetism. It showed a catalytic activity as high as 66%, which is much higher for the reaction than its precursor.The strong solid acid Zr(SO4)2 was dispersed on the nano-size magnetic support of Fe3O4 by ultrasonic waves. The optimum preparation conditions were confirmed under theassistances of the characterizations of the catalysts. The preparations of Zr(SO4)2/SiO2/Fe3O4 and Zr(SO4)2/ZrO2/Fe3O4 ctalysts by step wise depositions of the active components were also attempted.