<![CDATA[Layered double hydroxides (LDHs) are promising heterogeneous base catalyst for transesterification of various feedstock oils into biodiesel due to their tunable structure and favorable catalytic properties. Besides, LDHs contribute to environmental sustainability due to their ease of separation and ability to be reused for multiple catalytic cycles. However, LDHs often suffer from mass transfer limitations and particle aggregation, which reduces the accessibility of active sites and reduces catalytic efficiency. Biochar was introduced as a support material in LDH to investigate the influence of it on the catalyst properties and catalytic performance in transesterification. In this study, MnAl LDHs supported with banana peel biochar (MnAl/BPB) were synthesized using an alkali-free co-precipitation method with different MnAl ratios (i.e., 2:1, 3:1, and 4:1). The synthesized LDH were calcined to produce corresponding layered double oxides (LDOs) for catalytic evaluation in transesterification of waste cooking oil. The alkali-free synthesis approach was employed as a greener alternative to conventional methods, while ensuring higher purity and more consistent catalytic performance of LDHs. Among the synthesized catalysts, Mn4Al demonstrated the optimum physiochemical properties and was therefore selected for the transesterification process. Mn4Al-LDO showed excellent catalytic performance at optimum parameter of 21:1 methanol:oil ratio, 3 wt% catalyst, and 65℃ for 2 hours, achieving a fatty acid methyl ester (FAME) yield of 99.63%. In contrast, under the same parameter, Mn4Al/BPB-LDO exhibited lower FAME yield (68.46%) demonstrating that biochar did not enhance unsupported catalysts. Pristine Mn4Al-LDO also exhibited good stability, maintaining effective catalytic activity for up to five reuse cycles.]]>
