Preparation And Evaluation Of Biodiesel Magnetic Solid Catalyst

At present, liguid catalyst is mainly utilized in biodiesel industry, but there are problems such as equipment corrosion, environment pollution and complex process. Biodiesl solid catalyst is becoming more and more important because it is an effective way to solve these problems. However, solid catalyst is hard to be recycled completely with complex technology. Magnetic solid catalyst not only has advantages of the solid catalyst but also is easy to be recycled and operated. In this dissertation, magnetic solid catalyst was prepared, and the main content and results were as follows:1. Magnetic core was prepared with co-precipitation method and its Specific Saturation Magnetization reached 70.11 emu/g. This magnetic core was innovativly introduced into the catalyst made in our lab. So the carrier SiO₂ of this catalyst could play two roles: loading active component and protectiong magnetic core. The magnetic solid catalyt could be recycled easily and efficiently. The process to prepare the catalyst was confirmed as follows: dispersing the magnetic core in sol with ultrasonic method→forming gel→aging→filtrating gel in vacuum→drying in vocuum→crushing→prewetting—"-impregnating—* drying in vocuum→calcining.2. Single factor and orthogonal experiment were applied to research the process to prepare magnetic solid catalyst, and finally the optimal conditions were confirmed as follows: Si/Fe molar ratio 2, aging temperature 65℃, aging time 3h, K/Si molar ratio 1.5, calcining temperature 450℃, calcining time 3h. By characterization with Infrared Ray, X-ray Diffraction, Vibrating Sample Magnetometer, Scanning Electron Micrographs, it was found that the component of the catalyst was K₂CO₃/SiO₂-Fei₃O₄ therein SiO₂ and K₂CO₃ were both amorphous structure, the Specific Saturation Magnetization value of magnetic solid catalyst was 4.18 emu/g and the surface of the catalyst was sintered, but there were small particles of magnetic carrier under the surface.3. By single factor and orthogonal experiment, the reaction conditions to procduce biodiesel with magnetic solid catalyst were optimized as follows: catalyst dose 10%, molar ratio of methonal to oil 12, reaction temperature 65℃, reaction time 40 min, and stirring speed 400r/min. Under the optimal conditions, the comparative conversion was 105.48% in the first reaction, 99.50% in the second reaction. The magnetic solid catalyst could be reused; moreover it could be regenerated to prolong its application by calcining.