The Transesterification Reaction Of Abandoned Animal Fat Catalyzed By Magnesia And Zinc Aluminum Composite Solid Base Modified By Zirconia

Since the energy crisis and environmental pollution problems, the development of renewable and environmentally friendly alternative energy initiatives is imperative, one of the important hot spots of new energy research projects in the current is biodiesel undoubtedly.In this work, the experiment mainly explores the Zr O2 modification of Mg O complex oxides solid base catalysts, and new type of solid alkali catalyst for zinc aluminum complex oxides load Zr O2. Respectively investigated the preparation conditions of the solid alkali catalysts on coprecipitation method and impregnation method, then then the performance of the catalysts were characterized and the service life were studied, in order to determine the best preparation conditions of catalysts. At the same time, the transesterification reaction effecting factors were investigated by single factor experiments and multi-factors orthogonal experiments, and optimized the best process conditions.The best preparation condition for Zr O2-Mg O catalyst with co-preparation method: Mg:Zr molar ratio is 3, roasting 4h under 500 ℃ in air atmosphere. The best preparation condition for Zr O2/Zn O-Al2O3 complex oxides catalyst with impregnation method: in the hydrotalcite precursor Zn/Al molar ratio is 2, calcination conditions is 600 ℃ in the air; then the Zn O-Al2O3 complex oxide precursor loaded on 7% of Zr O2, and roasted 4 h under 550 ℃ in air atmosphere.The catalyst samples were characterized by adsorption/desorption of N2 at low temperature, scanning electron microscope(SEM), X-ray diffraction(XRD)and temperature programmed desorption of CO2(CO2-TPD). The results show that the catalysts have good specific surface area, total pore volume, and pore diameter are all ideal. Seen from the microstructure of the catalysts, its particle size distribution uniform and particle configuration is good, Zr O2 crystal conditions is good and evenly dispersed on the precursor, and the catalysts have strong base strength.This thesis selects the highest activity catalysts Zr O2-Mg O complex oxides solid base catalyst and 7% Zr O2/Zn O-Al2O3 hydrotalcite load type solid base catalyst in the application of the experimental research for biodiesel synthesis respectively, the optimal reaction conditions of transesterification process were investigated by single-factor and orthogonal experimental method analysis:For Zr O2-Mg O composite oxides catalyst the optimum technological conditions are: alcohol oil molar ratio is 45:1, reaction temperature is 240 ℃, dosage of catalyst is 0.1 g, reaction time is 100 min, and the alcohol oil molar ratio is the most important factor to the reaction, the transesterification conversion rate can reach more than 99%. For 7% Zr O2/Zn O-Al2O3 composite oxides load type solid base catalyst the optimum technological conditions are: alcohol oil molar ratio is 45:1, reaction temperature is 220 ℃, dosage of catalyst is 0.35 g, reaction time is 130 min, the transesterification conversion rate over 98%, and the most important influence factor on the ester exchange reaction is the dosage of catalys.The service life of the catalysts were investigated by repeating the ester exchange reaction, the activity of Zr O2-Mg O composite catalyst is as high as 98% after repeating 5 times, even 7%Zr O2/Zn O-Al2O3 composite oxides catalytic activity remained above 85% when repeated 15 times, the results indicated that the preparation of solid base catalysts have long service life and good stability.