Magnetic alumina composite microspheres with γ-Fe 2 O 3 core/Al 2 O 3 shell structure were prepared by the oil column method. A dense silica layer was deposited on the surface of γ-Fe 2 O 3 particles （denoted as γ-Fe 2 O 3 /SiO 2 ） with a desired thickness to protect the iron oxide core against acidic or high temperature conditions. γ-Fe 2 O 3 /SiO 2 /Al 2 O 3 particles with about 85 wt% Al 2 O 3 were obtained and showed to be suitable for practical applications as a magnetic catalyst or catalyst support due to their magnetic properties and pore structure. The products were characterized with scanning electron microscope （SEM） and transmission electron microscope （TEM）, nitrogen adsorption-desorption, and vibrating sample magnetometer （VSM）. The specific surface area and pore volume of the γ-Fe 2 O 3 /SiO 2 /Al 2 O 3 composite microspheres calcined at 500 ？ C were 200 m 2 /g and 0.77 cm 3 /g, respectively.
Qingtao FuTingting HeLianqing YuYongming ChaiChenguang Liu
