Solid Base-catalyzed Preparation Of Biodiesel

This paper adopts the heterogeneous method to prepare biodiesel,and the preparation technology for biodiesel are also investigated.Thirty-six novel and supported solid-base catalysts are designed and prepared using artificial zeolites,ZrO₂, CaO and so on as the carriers,and alkali metals and alkali earth metal salts as the active ingredients in our laboratory.Taking the Jatropha Curcas L.seed oil produced in Guizhou Province as the raw material,the catalysts with high activity were selected through transesterification of Jatropha Curcas L.seed oil and methanol.Then the preparation conditions of the catalysts with high activity are optimized in terms of preparation method,active ingredient to carrier mass ratio,calcination temperature, calcination time.The optimal preparation conditions for catalyst KOAc/artificial zeolites are following:impregnation method,active ingredient/carrier mass ratio 9:10, calcination temperature 550℃and calcination time 4 h.And the catalyst KOAc/artificial zeolites were characterized by means of X-ray diffraction and IR spectroscopy,as well as Hammett indicator titration.The results revealed a strong dependence of catalytic activity on basicity.The optimum reaction conditions for transesterification of J.curcas oil were also investigated using KOAc/artificial zeolite as the catalyst and are following:atmosphere pressure,oil/methanol molar ratio 1:8,2 wt.%catalyst amount,methanol reflux temperature and 4 h reaction time.Under above mentioned optimum reaction conditions,92.45%yield of the product with 92.72%methyl esters content was obtained.The reaction conditions for transesterification of marketed rapeseed oil.and methanol are optimized using microwave heating mode in the presence of the catalyst K₂CO₃/artificial zeolite.The optimum reaction conditions for transesterification of rapeseed oil in the presence of the catalyst K₂CO₃/artificial zeolite were obtained:100℃microwave temperature,150 W power output,3 wt.%catalyst amount,50 min reaction time and methanol/oil molar ratio 8:1.91.89%yield of the product with 91.72%methyl esters content was obtained under above conditions.The conventional heating method was also used to prepare biodiesel in order to compare with the data obtained under microwave heating mode.The results showed that when transesterification reaction was carried out for 50 min under conventional heating,the product was obtained in 89.07%yield with 69.57%methyl esters content.Thus the methyl esters content was considerably lower when compared with that of the result obtained under microwave irradiation.Comparable yield(91.03%) and methyl esters content(91.21%) under conventional heating were only obtained with extended reaction time of 240 min.Therefore,microwave operation is faster and more effective method for biodiesel production than conventional heating mode.