Research On Synthesis Of Biodiesel By Diatomite Suppotred Calcium Oxide Catalyzed Transesteriifcation

Biodiesel is a new alternative energy sources，and it is greatly significative in solving the problems ofenergy shortage and environmental pollution. In the traditional methods，the homogeneous catalyst aremainly used to catalyze the synthesis of biodiesel，there are many problems in the actual production，forexample，the homogeneous catalyst bring problems of separation and environmental pollution. However，these problems can be avoided effectively with the heterogeneous catalyst. In this paper，rapeseed oil andmethanol were used as raw material，heterogeneous supported catalyst was used as catalyst for theproduction of biodiesel. The main contents are as follow：(1) Analyse the character of rapeseed oil. The results show that acid value was0.63mg/g，saponification value was181.75mg/g，moisture and volatile matter content was0.18%，and the averagemolecular weight of rapeseed oil was934.38g/mol. Calculation of glycerol yield was used to assess thecatalytic activity of catalysts．(2) After high-temperature activation of calcium oxide was used in the transesterification to producebiodiesel. Through single factor and orthogonal experiments，the optimal transesterification conditionswere found as follows: methanol/oil molar ratio10:1，the amount of catalyst1%，reaction temperature60℃，and reaction time3h. The results showed that the yield of glycerol was83.5%.(3) The results of precursor and carrier selection experiments showed that CaO/diatomite catalystdisplayed highest catalytic activity. Its suitable preparation conditions were: precursor impregnatingsolution concentration22.6%，calcination temperature700℃，calcination time5h.(4) CaO/diatomite was used in the transesterification to produce biodiesel. Through single factor andorthogonal experiments，the optimal transesterification conditions were found as follows: the amount ofcatalyst4wt%，methanol/oil molar ratio12:1，reaction temperature70℃，and reaction time2h. The resultsshowed that the yield of glycerol was87.1%. The catalyst was used repeatedly for5cycles and the yields of glycerol were all above80%.(5) Structure and composition of the biodiesel products were characterized by means of infraredspectrometry (IR)，gas chromatography/mass spectrometry (GC/MS)，and nuclear magnetic resonance(NMR) spectroscopy. The main properties (acid value、saponification value、moisture and volatile mattercontent、density、kinematic viscosity、solidifying point、flash point、distillation range) of the biodieselproducts accord with the Chinese biodiesel standard.