This study investigates the use of cordierite honeycomb monoliths coated with solid acids such as zirconia, Mo(VI)/ZrO2 and Pt‐SO42−/ZrO2 and solid bases like zirconia–calcia, zirconia–magnesia mixed oxides in the synthesis of biodiesel from oil (PG‐oil). Solid acids were used for the esterification of free fatty acids in PG‐oil with methanol to reduce the percentage of free fatty acids in the oil followed by transesterification of PG‐oil over solid bases to synthesize biodiesel. The oxide catalysts were coated on honeycombs by an impregnation technique and characterized for their surface acidity/basicity, crystallinity and morphology. The effect of the molar ratio of PG‐oil/methanol in esterification and transesterification was studied. Reactivation and reusability of both solid acid and solid base catalysts was investigated. The catalysts were also prepared in their powder forms and their activity was compared with that of honeycomb coated forms. A twofold increase in the yield of biodiesel was obtained when the catalysts were used in honeycomb coated forms. The results revealed that the honeycombs coated with mixed oxides such as zirconia–calcia and zirconia–magnesia were economical, efficient and eco‐friendly (3e concept) for biodiesel production with ~95 % yield.

In this article production of biodiesel from Madhuca indica oil (MI-oil) containing high % of free fatty acids (FFA) by transesterification process with methanol over basic zeolites such as NaY loaded with 5-25% KOH is presented. The zeolites were characterized by PXRD, BET and CO 2 -TPD methods prior to their catalytic activity studies. Optimization of reaction conditions for transesterification was conducted in order to get highest possible yield of biodiesel. 1HNMR and FTIR analysis confirms the conversion of MI-oil to biodiesel. The physico-chemical properties of MI-biodiesel were found to be comparable with that of the standard biodiesel. The NaY and KOH/NaY zeolites were found to be efficient and reusable catalysts without much loss of their catalytic activity when used for several times in biodiesel production.

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