Study On The Preparation Of Biodiesel Through Transesterification Catalyzed By Calcium Glyceroxide

With the continuous development of biodiesel technology,higher environmental requirements for the production process of biodiesel from raw materials to products are proposed.Therefore,the raw materials,products,reaction processes and separation processes of the biodiesel industry need to be optimized in a green,efficient and sustainable direction.In this thesis,a method for preparing high-quality biodiesel with high acid value oil ester as the raw material was proposed.The techiques of glycerol esterification for acid reduction coupled with transesterification catalyzed by calcium glyceroxide were adopted.Palmitated oil with the acid value of 160.7 mg K??·g^-1was selected as the feedstock.Firstly,the calcium glyceroxide catalyst was prepared using calcium oxide as the precursor,which was characterized and evaluated.Then,the reaction kinetics of calcium glyceroxide catalyzed transesterification reaction was studied using anhydrous and low acid value glycerides as the raw material.Based on the material balance,the process of calcium glyceroxide catalyzed transesterification and product separation was studied,which was compared with the traditional KOH catalyzed transesterification process.In order to establish a green and efficient method for preparing high-quality biodiesel with high acid value oil,the advantages of glycerol esterification for acid reduction coupled with transesterification catalyzed by calcium glyceroxide were analyzed;Finally,the entire biodiesel production process was simulated by Aspen Plus software,which provided basic data and design basis for its industrial application.The details and results are as follows:?1?The calcium glyceroxide catalyst was prepared using calcium oxide as the precursor.The optimal preparation conditions were:calcium oxide:glycerin:methanol molar ratio of 1:12:10,reaction temperature of 60?,stirring rate of 600 r·min^-1,reaction time of 4 h.The obtained calcium glyceroxide was characterized by XRD,FTIR,TG-DTG and BET.The results show that the purity of calcium glyceroxide was as high as 99%.The calcium glyceroxide was easily decomposed at high temperature due to the existence of glycerin group,with the decomposition temperature of about205?.The calcium glyceroxide had a regular crystal structure of 65.14 m²·g^-1,with the alkali content being 7.2 mmol·g^-1.In addition,the solubility of calcium glyceroxide in methanol,glycerol,methy lester and glycerides systems was determined.The results show that the solubility of calcium glycerolate in the solvents followed the order of methanol,glycerol,glycerides,and methyl ester.?2?Using palmitated oil as the raw material,the glyceride with an acid value of0.7 mg K??·g^-1was obtained by the glycerol esterification method.The process of preparing biodiesel by calcium glyceroxide catalyzed transesterification was further studied.The influence of stirring rate,catalyst amount,methanol amount and reaction temperature on the transesterification reaction was investigated.The optimal preparation conditions were obtained:stirring rate of 600 r·min^-1,catalyst amount of 1%of the oil weight,methanol amount of 40%of the oil weight,reaction temperature of60?.The reaction kinetics of the calcium glyceroxide catalyzed transesterification was further studied,and the kinetic rate constants under 318.15-338.15 K was obtained.The results show that all reaction rate constants increased with increasing temperature,and the activation energy of each reaction was further calculated.The concentrations of glycerides and methanol can be predicted well by the kinetic model the calcium glyceroxide catalyzed transesterification.?3?The glyceride mixture prepared by glycerol esterification was used as the raw material to prepare biodiesel with calcium glyceroxide and KOH as the catalysts.Based on the material balance,the difference between the reaction process and the product separation process was compared.The total yield of methyl esters in the biodiesel production process was increased with the use of calcium glyceroxide catalyst,with the total yield of methyl esters reaching as high as 82.3%.By comparison,the total methyl ester yield was only 76.5%when the KOH catalyst was used.The catalyst cost can be reduced by about 46.8%using calcium glyceroxide as the catalyst.In addition,the asphalt produced by calcium glyceroxide catalyzed biodiesel production was about 5.8%lower than the that from the KOH catalyzed process,which greatly reduced the processing cost.?4?The process of processing 100,000 tons of palmitic acid oil per year to produce biodiesel was simulated using Aspen Plus.The process includes the recycling of materials,the optimization of the operating conditions of the corresponding equipment and the optimization of the heat exchange network,with 17.5%of energy can be saved through heat exchange optimization.The optimal process design conditions for each section were obtained.Under the optimal operating conditions,the consumption of various raw materials,product output and output of wastes were obtained through the overall material balance.The energy consumption of public works was obtained through energy balance.On this basis,the profit for processing one ton of palmitated oil reached 1173 yuan according to the economic evaluation.