Study On Preparation Of Solid Base Catalyst And Its Catalytic Synthesis Of Biodiesel

Biodiesel is a renewable diesel fuel that can be replaced by petrochemical diesel by transesterification or other methods using vegetable fats or animal fats,food waste oil,etc.as raw materials.It has the advantages of being renewable and clean.The transesterification method is currently the main method for preparing biodiesel.The solid base catalyst used in it has strong applicability and high catalytic efficiency.In this thesis,two supported solid alkali catalysts were prepared,using pretreated leprosy seed oil as raw materials,and the preparation process of the catalyst and its catalytic synthesis of biodiesel were studied.?1?Preparation of KF/Ca-Mg-Al-O catalyst.Co-precipitation method and equal-volume impregnation method were adopted successively.Fatty acid methyl ester?Fatty acid methyl ester,hereinafter abbreviated as FAME?yield was used as the index.The single-factor screening was used to prepare the best conditions.The response surface optimized KF/Ca-Mg-Al-O catalyst preparation process.The results show that the best process is:magnesium to aluminum molar ratio 3.5:1,Ca dosage is 2%,KF loading is 24.0%,calcination temperature is 657^oC,calcination time is 3.7 h.Infrared spectroscopy?FT-IR?,X-ray diffraction?XRD?,scanning electron microscopy?SEM?,thermal weightlessness analysis?TG-DTG?and Hammett's alkaline determination method were used for KF/Ca-Mg-Al-O The characterization was carried out and the results showed that KCa F₃was formed and played a catalytic role.Moreover,after calcination,the catalyst has a porous structure,which increases the reaction area and plays a role in enhancing the catalytic effect.?2?Preparation of magnetic attapulgite catalyst.The in-situ precipitation method and the equal volume impregnation method were used successively.The FAME yield was used as the index.The single factor selection was used to prepare the best conditions.The response surface optimized the preparation process of the magnetic attapulgite catalyst.The results show that the best process is:the dosage of the modifier cetyl triammonium bromide?CTAB?is 29 mmol/100g,the KF loading is 29%,the calcination temperature is 278^oC,and the calcination time is 2.8 h.The obtained catalysts were characterized by infrared spectroscopy?FT-IR?,X-ray diffraction?XRD?,and scanning electron microscopy?SEM?methods.The modified magnetic attapulgite catalyst was characterized and formed by the formation of K₂O after calcination at high temperature catalytic activity.?3?Research on biodiesel preparation technology.KF/Ca-Mg-Al-O catalyst and magnetic attapulgite catalyst were used to catalyze the transesterification reaction respectively.The deacidified leprosy seed oil was used as raw material to investigate and optimize the preparation process of biodiesel.The yield of FAME was adopted Analyze by gas chromatography and optimize its preparation process with response.First,the deacidification process is studied.The deacidification method of leprosy seed oil is the method of multiple extractions with methanol.Finally,the acid value of the leprosy seed oil after deacidification was 0.84 mg KOH/g.When preparing biodiesel with KF/Ca-Mg-Al-O catalyst,the best preparation process is:catalyst dosage 3 wt%,alcohol-oil molar ratio 9.8:1?mol:mol?,reaction temperature 66^oC,reaction time3.5 h,The FAME yield is 95.19%.When preparing biodiesel with magnetic attapulgite catalyst,the best preparation conditions are:catalyst dosage 5.5 wt%,alcohol-oil molar ratio 9:1?mol:mol?,reaction temperature 55^oC,reaction time 4 h,FAME 95.23%.?4?After repeating KF/Ca-Mg-Al-O catalyst for 7 times,the FAME yield decreased by2.87%and the downward trend was slow,and the reusability was good,which could meet the production demand.After repeated use of the magnetic attapulgite catalyst for 7 times,the FAME yield decreased by 10.37%,and the preparation process needed to be improved.