Studies on the development of novel heterogeneous catalysts for transesterification of triglycerides catalysts for transesterification of triglycerides in biodiesel in biodiesel Gomes, J. F. P., Puna, J.F., Bordado, J.C., Correia, M.J.*, Dias, A.P.* IBB – Institute for Biotechnology and Bioengineering, Centre for Biological and Chemical Engineering *Centre for Chemical Processes/ICEMS Instituto Superior Técnico, Av. Rovisco Pais, Lisboa, Portugal Introduction Results and Discussion Materials and Methods References Acknowledgments Conclusions An important drawback related with the use of homogeneous catalysts for bioidiesel production is that, they have to be neutralized after the end of the reaction, thus producing salt streams. Moreover, due to the presence of free fatty acids, homogeneous catalysts react to form soaps as unwanted by-products, hence requiring more expensive separation processes. Therefore, there is currently, a drive towards the development of industrial processes for biodiesel production using solid catalysts. The key benefit of using these heterogeneous catalysts is that, no polluting by-products are formed and the catalysts do not have to be removed since they do not mix with the biodiesel. In addition to lower separation costs, less maintenance is needed as these catalysts are not corrosive. Several experiences were performed, in a 500 mL glass batch reactor, in order to promote the conditions for transesterification reaction with solid alkaline catalysts. All experiences were performed at ºC, with reflux, using soya pre-treated oil, a molar ratio methanol:oil of 12:1, a catalyst weight percentage of 5% related to oil and, a reaction time between 5 and 7 h. To improve mixture, it was used a mechanical agitator. The oil before use, was submitted to a specific treatment. The methyl esters (ME) product reaction was separated from glycerine and, after that, biodiesel was subjected to a purification process (3 washings with water and acid nitric 1,5%, centrifugation and drying), in order to eliminate, water, methanol and other water soluble impurities. Finally, each sample was analysed by NIR (Near Infra Red Spectrometer) equipped with FTIR, to preview the yield of biodiesel (%ME) and its density at 15º C. The used catalysts were prepared by impregnation or by co-precipitation methods, with the appropriate precursors and supports and, calcinated at high temperatures in order to activate them. Regarding results from table 1 and, also, figure 3, it is possible to conclude that, catalysts who showed a higher yield of ME in the second step, so far, was Li supported on calcium oxide, prepared by impregnation or, only, CaO. These solid catalysts appears to be suitable for transesterification reaction, to produce biodiesel. However, it is important to perform further experiences with these catalysts to optimise the operating conditions and, also, continue to investigate the performance of earth alkaline metal catalysts, for instance, Ca and Sr, supported in Alumina, and, also, Li supported in Alumina, and, finally, hidrotalcites of MgAl and MgCa, all of them as basic catalysts. HETEROGENEOUS ALKALINE CATALYSTS NAME CALCINAT ION SOURCE % ME Dens. 15ºC ZnAl 2 O 4 (2ºA)-ZnAl 2 O 4 0,5919 K/Al 2 O 3 (2ºA)-K/Al 2 O 3 -0,5920 Mg/Zr 2:1 (2ºA)-Mg/Zr 2:1-1,9920 Ca/Al 2 O 3 (2ºA)-Ca/Al 2 O 3 -1,1920,5 MgAl 5:8 (2ºA)-MgAl 5:8-0,4919,1 Sr/CaO (2ºA)575ºC, 4hSrO/CaO-1,0919,9 Higher Base CaO (2ºA) 575ºC, 4h Higher Base CaO 2,8918,3 Li/CaO (2ºA)-Li/CaO92,7889,5 CaO (2ºA)-CaO96,5884,3 Table 1: Heterog. catalysts used in 2 nd step transesterification reactions. Figure 2: NIR spectrum of homogeneous biodiesel (left) and with Li/CaO (1A) heterog. catalyst (right). Figure 1: Transesterification reactor. Figure 3: Preview yield for Biodiesel, by NIR, in 1 st and 2 nd steps transesterification reactions. Gomes, J.F.P., Puna, J., Bordado, J.C., Correia, J.N., “Development of heteogeneous catalysts for transesterification of triglycerides”, Reaction Kinetics and Catalysis Letters, 95(2), (2008) Puna, J., Gomes, J.F.P., Correia, J., Soares Dias, A., Bordado, J., “Advances on the development of novel heterogeneous catalysts for transesterification of triglycerides in biodiesel”, Fuel, 89(11), (2010) Table 1 and figures 1, 2, and 3 shows relevant data related with these experiences. The 2 nd step transesterification reactions (2ºA) were only performed for those catalysts who showed a higher yield of ME in the first transesterification step. The authors would like to acknowledge the co-operation from members of the Centre for Chemical Processes of IST, namely Dr. Pedro Felizardo who provided the means for interpretation of NIR spectra.