Producing Biodiesel From Animal And Vegetable Fats Waste Oil By Modified Zinc Oxide Solid Base Catalyst

In recent years, environment problem and energy crisis have become increasinglyserious, people are looking for a new energy which is renewable, no pollution andenvironmentally friendly. Biodiesel, as a kind of green and environmental protection,renewable, clean and safe energy, has the great significance in solving energy crisis andenvironmental problems. Compared with traditional homogeneous acid-base catalysismethod, the new type solid base catalysis will have less corrosive effects to the equipmentand less waste liquid, the catalyst can be recycled. The main problem facing thedevelopment of biodiesel is high cost of raw materials. Therefore, it is very important tofind a kind of raw materials which is inexpensive and can be used for industrializedproduction. Using animal and vegetable fats waste oil to produce biodiesel, not onlysolves the problem of gutter oil recycling, avoid gutter oil going to people’s dining tables,but also has achieved industrial utilization value. This thesis aims to find a new efficientsolid base catalyst for the preparation of biodiesel which is low free fatty acid (FFA)content and low water content used catalytic process of ester exchange.This thesis studied using the modification ZnO solid base catalyst which areprepared with co-precipitation and impregnation method for the transesterification ofanimal and vegetable fats waste oil to biodiesel, and also the optimization of the catalystpreparation conditions, characterization and lifetime for the catalyst. At the same time,the ester exchange reaction conditions are optimized, the purity of byproduct glycerol isanalyzed.The best preparation condition for ZnO-Al2O3catalyst with co-preparation method:Zn/Al molar ratio is2, calcination3h at500℃in the air; The best preparation conditionfor ZnO-ZrO2catalyst with co-preparation method: Zinc/Zirconium molar ratio is5,calcination3h at700℃in the air. The best preparation condition for ZnO/Zn2Al-hydrotalcite catalyst with impregnation method: Zn2Al-hydrotalcite load10%ZnO,calcination3h at500℃in the air; The best preparation condition for ZnO/Al2O3/SiO2catalyst with impregnation method:20%ZnO loading on10%Al2O3/SiO2, calcination3hat500℃in the air.The catalyst is characterized by adsorption and desorption of N2at low temperature,X-ray diffraction instrument, CO2-TPD instrument. The results show that the catalystshave good surface structure and performance, specific surface area, total pore volume,and pore diameter are all ideal.This thesis selects the highest activity catalyst10%ZnO/Zn2Al-hydrotalcite in theapplication of the experimental research for biodiesel synthesis respectively. Orthogonal experimental method and single-factor analysis are conducted to investigate the optimalreaction conditions of ester exchange process: methyl alcohol and oil molar ratio is25:1,amount of catalyst is1.8%, reaction temperature is200℃, reaction time is2h. Esterexchange rate can reach98.7%. The order of the influence of factors on the reaction isreaction temperature, methyl alcohol and oil molar ratio, reaction time, amount of catalyst,and biodiesel production rate can reach85%.This thesis investigates the lifetime of catalyst, activity of the catalyst is over80%after used5times. The purity of byproduct glycerol is analyzed by gas chromatography,there is no impurity detected.