Oil palm trunk and sugarcane bagasse derived heterogeneous acid catalysts for production of fatty acid methyl esters

In this study, new catalysts were prepared from oil palm trunk (OPT) and sugarcane bagasse (SCB), which are available in enormous quantities. Effect of carbonization time with statistical validation, effect of reaction variables such as catalyst loading, methanol molar ratio, reaction time, alcohol selectivity, effect of grafting Keggin anions onto the multifunctional catalyst and composition of the biomasses were investigated. Under optimum conditions, the OPT and SCB catalysts afforded 88.8% and 96% yield of methyl palmitate, respectively. From statistical analysis, P-value (prob. > F) for OPT indicates that difference between the means of different carbonizations is not significant, but it is significant for SCB 4 h and 8 h carbonizations. In synthesis of ethyl palmitate and butyl palmitate, OPT catalyst gave FAME yield of 86.7% and 88% respectively, while SCB catalyst gave 90.7% and 91.6%, respectively. Grafting of Keggin anions by incipient wetness impregnation resulted in 3.6% increase in FAME yield, which shows that very few active sites consisting of Keggin anions and lacunary Keggin anions have been introduced. The catalysts are recyclable, and showed only 10.5–12.5% loss in activity after six cycles of repeated use. The catalysts are highly suitable for biodiesel production.