Transesterification of ethyl butyrate with methanol using MgO/CaO catalysts

A series of mixtures of MgO/CaO with different Mg/Ca molar ratios (between 3 and 15), as well as the corresponding pure oxides, was prepared by the coprecipitation method in a basic medium and Subsequent calcination. Their textural and structural characterization was carried Out by using XRD, FT-IR, SEM and N-2 sorption at 77 K. The alkalinity was studied by CO2-TPD and catalytic decomposition of 2-propanol. The MgCa oxides obtained after calcination at 1073 K exhibit X-ray diffraction patterns with clearly visible signals corresponding to crystalline CaO and MgO. Textural properties are improved by the presence of Mg, with the porosity increased and the particle sizes decreased with respect to pure CaO. FT-IR spectroscopy reveals the presence of surface carbonate. These catalysts are active in the transesterification of ethyl butyrate with methanol at 333 K and atmospheric pressure, a model reaction to evaluate the potential of these basic catalysts in triglycerides transesterification for biodiesel production. The highest activity was found for a Mg:Ca molar ratio of 3, with conversion close to 60%, whereas MgO was inactive. Moreover, lixiviation of the active phase was not observed thus excluding the contribution of the homogeneous catalysis to the studied transesterification process. (C) 2008 Elsevier B.V. All rights reserved.