Transesterification of Rapeseed Oil to Biodiesel on CaO/α-Fe Hollow Fiber Catalyst: Optimization by Response Surface Methodology

CaO/alpha-Fe precursor gel fibers have been successfully prepared using metal salts and citric acid (CA) by the organic gel-thermal decomposition method. Subsequently, these precursor gel fibers were calcined to introduce hollow structures into the fiber. The physical and chemical properties were further characterized by BET surface area, X-ray diffraction, scanning electron microscopy, temperature programmed desorption of CO2, and vibrating sample magnetometer, respectively. The magnetic property of alpha-Fe in CaO/alpha-Fe fiber provides the great advantage of reusing CaO catalytic activity for the transesterification of rapeseed oil to corresponding fatty acid methyl esters. The effects of various important parameters on the conversion ratio of biodiesel were optimized by utilizing response surface methodology analysis. The optimum conditions achieve 97 % biodiesel conversion ratio. In addition, the conversion ratio still remains 85 % after 20 times repetition. Therefore the loss of CaO/alpha-Fe fiber catalyst mass was minimal.