Preparation And Catalytic Reaction Lanthanum Carbonate Based Solid Base Catalyst Exchange

The catalytic transesterification is the mainly method for the preparation ofbiodiesel. In many kinds of catalysts, the supported solid base catalysts have beenattracted more attentions due to their characters of little corrosion,be easily removed,fast reaction rate and reusable in recent years. But there are still some defects for thesesolid base catalysts including high reaction temperature, small specific surface area andlow utilization of active sites. Therefore, preparation of a solid base catalyst with highactivity and stability is vitally theoretical and practical significance. In this paper, aseries of KF/La2O2CO3and KF/La2O3/Al2O3catalysts were prepared and the tributyrintransesterification reaction with methanol was selected as probe reaction to study thefactors that affect the performance of catalytic and the relationships between basic andcatalytic activity.The KF/La2O2CO3solid base catalyst was prepared on La2O2CO3supporter byimpregnation method. XRD, CO2-TPD, SEM, FT-IR, XPS were characterized to studythe relationship between the catalytic performance and its structure and basic. Theresults indicate that the effect of calcination temperature and KF content of KF/LOC onthe catalytic activity are very obvious. The25%KF/La2O2CO3(25-KF/LOC-773)catalyst at773K calcined exhibits excellent catalytic performance, it is mainly becausethere exists a mount of Br nsted basic sites on the catalyst surface. Reused and stabilitystudies over25-KF/LOC-773catalyst still remains good catalytic activity although thesample was stored90days or treated by CO2. The reused of25-KF/LOC-773catalystshows that it has lower catalytic activity at room temperature, while showing bettercatalytic activity at338K.For improving the utilization of La,a little lanthanum carbonate was precipitated toγ-Al2O3which displays a large specific surface area to increase the dispersion oflanthanum and expose more active sites. KF/La2O3/Al2O3was prepared by loading theactive species KF on La2O3/Al2O3support. Experimental results show that the catalyticperformance has been greatly improved although the content of lanthanum of KF/La2O3/Al2O3(1.64wt.%) is very low. Subsequently, the influence of calcinationtemperature and amount of loading on the activity of the KF/La2O3/Al2O3catalyst hasbeen explored. Compared KF/γ-Al2O3with KF/La2O3catalysts, KF/La2O3/Al2O3catalyst shows the better catalytic performance.