| At present,in the face of global environmental pollution and energy crisis,it has become a broad consensus among people to explore and prepare renewable clean energy.As a biofuel,biodiesel is a sustainable energy source.It can be a liquid environmentally friendly fuel that can be mixed with petroleum and diesel and can replace traditional fossil fuels.Biodiesel is an alkyl ester composed of long-chain carboxylic acids,which is biodegradable,environmentally friendly,and can significantly reduce greenhouse gas and toxic gas emissions.China's soybean consumption market is the largest in the world,so a large amount of bean drugs is produced every year,but the utilization rate of bean drugs is very low.Therefore,extracting oil from bean drugs as a raw material is an ideal choice for the production of biodiesel.1.Analyzing the physical and chemical properties of soybean dregs oil and the results are as follows:the acid value is 4.17 mg KOH/g,the molecular weight is 876,and the saponification value is 196.3 mg·g-1.Due to the high acid value of the extracted soybean residue oil,the acid value is reduced to 1.82 mg KOH/g according to the method in the literature,which can be used for the transesterification reaction.2.The experiment is to synthesize the basic catalyst of CaO and Al2O3 mixed metal oxide by sol-gel method.It is used in the reaction of mixing soybean dregs oil and ethanol to prepare biodiesel.TG,FTIR,XRD,BET,SEM-EDX,TEM-EDX,CO2-TPD were used to analyze the composition,structure and basicity of the catalyst.Characterization confirmed that calcination of the catalyst at 750oC is the most appropriate.The best conditions are that the catalyst is calcined at 750oC,the calcination holding time is 4h,catalyst dosage 8wt.%,the alcohol-to-oil molar ratio is12:1,the reaction is at 75?for 3 h,and the maximum yield of biodiesel is 92.6%.After five reuse experiments,the yield is still higher than 76%.After the catalyst was recalcined,the yield increased by 8.1%.The oil and glycerin in the reaction system covered the surface of the catalyst,causing the catalyst to stick together,and the precipitation of calcium ions were the two main reasons for the decrease in yield.The experimental data can conform to the pseudo first-order kinetic model(R2=0.9674).The energy required to prepare biodiesel using the catalyst is 62.36 KJ/mol.3.The test of soybean dregs oil biodiesel showed that the ingredients mainly include ethyl linoleate(58.4%),ethyl oleate(7.8%),ethyl palmitate(6.76%),ethyl stearate(4.23%),flax ethyl acid(2.98%).The test is carried out according to the GB25199-2017 standard.The test results are compared with GB.The flash point is168°C,the moisture content is 0.047 wt.%,the viscosity is 4.6 mm2/s,the density is892 kg/m3,and the acid value is It is 0.43 mg KOH/g,which meets GB requirements.4.The sterol extraction experiment was performed in the lower layer solution after the centrifugation of the biodiesel.The saponification process and the extraction process were the main research objects.The single factor analysis of the extraction conditions showed that the best sterol extraction result was 3.6 mg/g. |
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