Preparation Of Composite-metal Oxide Base And Study Catalytic Synthesis Of Biodiesel

Biodiesel,a green renewable energy source,is recognized as a good alternative to fossil diesel,helping to overcome limited fossil fuel resource shortages and environmental pollution problems.The solid base has the advantages of high activity,easy separation of products,and little corrosion to equipment.Vigorous research and development of solid base catalysts is of great significance for the industrial production of biodiesel.In this paper,solid base catalyzed transesterification of soybean oil with methanol was the main research object.The specific research contents are as follows:Ni-CaO-MgO solid base catalyst was synthesized by co-precipitation method by incorporating Ni into CaO-MgO.The effect of Ni incorporation on the catalytic activity was investigated under the same reaction conditions.The physicochemical properties of the prepared catalysts were investigated by XRD,HAADF-STEM,TG-TGA,SEM,TEM,BET,CO₂-TPD and other analytical techniques.The results show that Ni successfully incorporates and replaces part of Mg,which causes the MgO lattice to be distorted and produces a strong basic site.The reaction conditions were screened by investigating the effects of reaction temperature,reaction time,methanol/oil molar ratio and catalyst dosage on the yield of fatty acid methyl ester.The experimental results show that the biodiesel yield is 97.6%under the reaction conditions of reaction temperature of 120°C,reaction time of 1h,molar ratio of alcohol to oil of 27:1 and catalyst dosage of 5wt%.After the catalyst was used four times,the yield was lowered to 65.8%.The CeO₂-Fe₂O₃ support was synthesized by hydrothermal method,and then KF/CeO₂-Fe₂O₃ catalysts with different loadings were synthesized by impregnation method.The effect of KF loading on the catalytic activity was investigated under the same reaction conditions.The physicochemical properties of the prepared catalysts were investigated by XRD,TG-TGA,FT-IR,TEM,BET,CO₂-TPD and other analytical techniques.The results showed that the catalyst had a rod-like structure,and both Ce and Fe formed a solid solution structure.The biodiesel yield was 95.9%under the reaction conditions of a reaction temperature of 85oC,a reaction time of 4 h,an alcohol to oil molar ratio of 27:1,and a catalyst dosage of 5wt%.After the catalyst was used four times,the yield dropped to 76.7%.The MgO-La₂O₃ support was synthesized by hydrothermal method,and then K2CO3/MgO-La2O3 catalysts with different loadings were synthesized by impregnation method.The effect of K2CO3 loading on the catalytic activity was investigated under the same reaction conditions.The physicochemical properties of the prepared catalysts were investigated by XRD,FT-IR,BET,CO2-TPD and other analytical techniques.The experimental results show that the catalyst has good activity and stability.The biodiesel yield was 96.8%under the reaction conditions of a reaction temperature of 55oC,a reaction time of 2h,an alcohol to oil molar ratio of27:1,and a catalyst dosage of 5wt%.After the catalyst was used four times,the yield was lowered to 80.2%.