Ca-Mg-Al Hydrotalcite Catalyst For Transesterification Of Soybean Oil With Methanol To Produce Biodiesel

Two kinds of Ca-Mg-Al hydrotalcite catalysts (marked for HTLCs1and HTLCs2respectively) with different molar ratio of n(Ca)/n(Mg)/n(A1) were prepared byco-precipitation method using Ca(NO3)2and CaC2O4as different source of calcium.Themodified hydrotalcite catalysts were characterized by XRD,SEM,TEM,FTIR by means ofexperimental analysis.The results showed that the layers column frame structure ofhydrotalcite catalysts were damaged and formed the composite metal oxide,and the particlesize distribution was uniform,calcination temperature500℃.SEM results showed thatCa-Mg-Al hydrotalcite from Ca(NO3)2and CaC2O4existed in laminar,oval structure,andsimilar to Mg/Al hydrotalcite.The results also showed that Ca-Mg-Al hydrotalcite using calcium oxalate as calciumsource exhibited higher catalytic activity for transesterification of soybean oil with methanolto produce biodiesel,and esterification ratio of84.71%was attained under the optimalcondition as follows:reaction temperature65℃,molar ratio of methanol to soybean oil12:1,reaction time3h, and catalyst dosage4%of soybean oil mass.The catalyst still kept higheractivity after three repeated use times.