Influence of the Incorporation of Transition Metals on the Basicity of Mg,Al-Mixed Oxides and on Their Catalytic Properties for Transesterification of Vegetable Oils

The transesterification of vegetable oils produces fatty acid methyl esters (biodiesel). Biodiesel is a nonpolluting alternative fuel produced from renewable resources whose chemical and physical properties closely resemble those of the petroleum diesel fuel and does not contribute to the greenhouse effect. The use of solid catalysts makes biodiesel production processes environmentally friendly. In this work, Mg,Al-mixed oxides derived from Mg,Al-hydrotalcite-like compound with an M3+/(M2++M3+) molar ratio of 0.25, in which Mg or Al was partially replaced by Co2+, Cu2+, Cr3+, or Fe3+, were prepared, characterized, and evaluated as catalysts for the transesterification of soybean oil with methanol. The results have indicated that the incorporation of transition metal influenced both textural and base properties. All the evaluated catalysts were active for the studied reaction. The catalytic activity followed the order Cr-MO < Co-MO < Cu-MO < Fe-MO < MO and could be explained by mesoporous volume.