| Summary: | 碩士 === 國立臺灣海洋大學 === 輪機工程學系 === 103 === The application of homogeneous catalyst for biodiesel production can reduce processing time but create extra waste water and difficulty of catalyst separation from final product. In contrast, heterogeneous catalysts bear advantages of fast separation and repeatable use. The supporting material for a heterogeneous catalyst generally owns characteristics of high stability extent, high pore surface and chemical inactivity, etc. During reaction with a heterogeneous catalyst, reactant mixture is absorbed on the catalyst surface. The chemical bonds of the original chemical structure of the reactant were then broken to form new ones. The final product thereafter desorbs from the catalyst surface. Nanoparticles of titanium dioxide (TiO2) and zinc oxide (ZnO) were used as supporting materials and dispersed evenly in sodium methoxide (CH3ONa) solution of various concentrations by an ultrasonic vibrator for 1 hr. The solution mixture was then coated on a matrix by a dipping-coating method, dried and calcined to prepare heterogeneous catalysts of TiO2/CH3ONa or ZnO/CH3ONa. The catalyst structure and characteristics were then analyzed in order to establish the optimum preparation condition for the catalyst. The experimental results show that no significant weight loss for CH3ONa during the catalyst preparation. In comparison with that of ZnO, the chemical bond of TiO2 with CH3ONa increased with the concentration increase of the sodium methoxide solution. Heterogeneous film and powder catalysts were further prepared by dispersion of TiO2 nanoparticles in 0.5M sodium methoxide solution. The catalysts were thus applied to catalyze transesterification of methanol and soybean oil with molar ratios ranging from 5 to 9 at a reaction temperature of 65℃ for 1 hr. It was observed that the biodiesel produced with the heterogeneous powder catalyst at a molar ratio of methanol / soybean oil equal to 9 had the highest heating value and transesterification conversion fraction while the lowest kinematic viscosity. The carbon residue of the biodiesel produced with the heterogeneous film catalyst was lower than that with the heterogeneous powder catalyst. In addition, the biodiesel produced with either the catalyst at a molar ratio of methanol / soybean oil equal to 7 had the lowest acid values.
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