• biodiesel;
  • calcium oxide;
  • hollow fiber;
  • magnetic;
  • catalyst

Magnetic recycled calcium oxide hollow fibers were successfully prepared for the transesterification of rapeseed oil with methanol to produce biodiesel. The hollow fiber catalyst prepared from different molar ratios of metal ions, various annealing atmospheres and annealing temperatures were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, vibrating sample magnetometer, and Brunauer–Emmer–Teller surface area measurements. Under optimum conditions (Ca2+:Fe3+ = 1:2, reducing atmosphere annealing at 1000°C), magnetic calcium oxide hollow fibers with average pore size around 6.3061 nm, the surface area of 15.28 m−1, and saturation magnetization of 136.564 Am2 kg−1 were produced by organic gel-thermal decomposition. Then, their catalytic activities were studied, and 95.7% biodiesel yield was achieved. The catalyst was separated by a magnetic field and recycled 20 times, and 85.2% biodiesel yield was still obtained. Magnetic calcium oxide hollow fibers are active, stable, and easily separated green catalysts that may find practical uses in biodiesel industry. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 1255–1261, 2013