Study On Biodiesel Preparation From Transesterification Of Soybean Oil By Solid Base Catalysts

As a green, safe, renewable clean energy, biodiesel has the great significance in solving energy problems as well as the relative environmental problems. However, the traditional homogeneous acid-base catalyst in the catalytic synthesis of biodiesel transesterification is difficult to separate from the products, and a large number of waste water was generated in the separation, causing environmental pollution problems. As the environmental friendship of the solid alkali catalyst, and can solve the above defect of the homogeneous catalyst, so with high solid alkali catalyst biodiesel synthesis experiment and theoretical research is very meaningful.In this paper, four kinds of catalysts were prepared by impregnation. These four kinds of catalysts were characterized and were studied for synthesis of biodiesel in the applications. Taking K₂CO₃ and CH3COONa as raw materials, the solution was respectively made in concentration10% and 20%.The Al₂O₃ powders were supersaturated impregnate by these solutions respectively for 12 hours, dried 4 hours at 105℃, calcined 3 hours at 500℃, then after natural cooling, four kinds of load-based solid catalysts were obtained, as 20% K₂CO₃/Al₂O₃, 10% K₂CO₃/ Al₂O₃, 20% Na₂O / Al₂O₃, 10% Na₂O / Al₂O₃.The catalyst was characterized by scanning electron microscopy, pore size and surface area measuring instrument, infrared spectrometer,which was to analyze the surface structure and performance of the catalyst. The results showed that the catalysts had good surface structure and performance, and the particle size was well-distributed, and active component was also evenly distributed in the carrier as well as particle surface area, pore volume, pore size were all ideal.These four kinds of catalysts were in the application of experimental research for biodiesel synthesis respectively. Orthogonal experimental method and single-factor analysis were conducted to investigate the optimal reaction conditions, combined with the comprehensive consideration in production rates and energy consumption, get the optimal reaction conditions for biodiesel production by four kinds of catalysts: the optimal reaction conditions by 20% K₂CO₃/Al₂O₃ was 12:1 alcohol and oil molar ratio, 60℃reaction temperature, 4 hours reaction time, 3% amount of catalyst; the optimal reaction conditions by 10% K₂CO₃/Al₂O₃ was 12:1 alcohol and oil molar ratio, 60℃reaction temperature,3 hours reaction time, 3% amount of catalyst; the optimal reaction conditions by 20% Na₂O / Al₂O₃ was 12:1 alcohol and oil molar ratio, 65℃reaction temperature,4 hours reaction time, 2% amount of catalyst; the optimal reaction conditions by 10% Na₂O / Al₂O₃ was 9:1 alcohol and oil molar ratio, 60℃reaction temperature,4 hours reaction time, 2% amount of catalyst; Experimental results showed that the best catalyst was 20% Na₂O / Al₂O₃, such a catalyst in the catalytic synthesis of biodiesel applications, the highest biodiesel yield is 85.4%.The composition and the physical and chemical properties of biodiesel were analyzed, and the results show that biodiesel had a good performance.Finally, the economic feasibility analysis for the preparation of biodiesel was to carry out. The key to the large-scale production of biodiesel was to ensure the biodiesel sources of raw materials and control raw material price of biodiesel.