Biodiesel production optimization using γAl2O3 based catalysts

The transesterification reaction of soybean oil with methanol is studied with different γAl2O3 heterogeneous catalysts. The catalysts used are K-γAl2O3, Na-γAl2O3, Li-γAl2O3, Ca-γAl2O3 and Ba-γAl2O3 both 5% and 10% in metal content are prepared by impregnation. The first study concluded that only two of the ten catalysts studied (K-γAl2O3, Na-γAl2O3 with 10% content in metal) gave a FAME (Fatty acid methyl esters) yield result higher than 90%. A mixed-level design of experiments is used to know which the best catalyst is between the K-γAl2O3 and the Na-γAl2O3 with 10% content in metal. Also, a factorial design of experiments and central composite designs have been used with K-γAl2O3 with 10% content in metal, which resulted the most active catalyst. The chosen variables are reaction time, initial catalyst percent and methanol:oil ratio, while the response is the biodiesel yield. Soybean heterogeneous transesterification is strongly affected by the methanol:oil ratio and it is slightly affected by the catalyst percent. Nevertheless, reaction time has no important effects in the biodiesel yield. Finally, the industrial application of the soybean biodiesel as determined through the study of the quality control of the biofuel and the reuse of K-γAl2O3 with 10% content in metal.