Synthesis of a reusable novel catalyst (β-tricalcium phosphate) for biodiesel production from a common Indian tribal feedstock

Abstract

In recent times, the rate of energy consumption goes on increasing and the world is desperately searching for new sources of fuel. Biodiesel (fatty acid methyl esters) is an alternative renewable energy resource for the next generation. Biodiesel has several advantages which include its non-toxic nature, it is biodegradable and it reduces greenhouse gas emissions. β-Tricalcium phosphate (β-Ca₃(PO₄)₂) catalyst was synthesized from fish waste. Fish waste contains calcium phosphate which is converted into β-tricalcium phosphate since it has low crystallinity and hydroxyl (OH) groups which decrease the potential to be a good catalyst for the synthesis of biodiesel through transesterification. This paper explores the synthesis of biodiesel using β-tricalcium phosphate (β-Ca₃(PO₄)₂) as a heterogeneous catalyst. Pongamia pinnata (Karanja) oil was extracted from seeds through the solvent extraction process. Intended for the development of easier transesterification process, stable and active heterogeneous β-tricalcium phosphate (β-Ca₃(PO₄)₂) catalyst was synthesized and used for the P. pinnata (Karanja) oil transesterification process. The synthesized heterogeneous catalyst was characterized by XRD, FT-IR, SEM and EDX to determine its structural and morphological characteristics. The catalyst exhibited good catalytic activity on reuse. Biodiesel yield was greatly dependent on operating parameters such as catalyst concentration, methanol to oil molar ratio, reaction temperature and reaction time. Effect of co-solvent on biodiesel was studied by using different co-solvents in transestrification reactions. High quality and maximum biodiesel yield (97 %) was obtained under the optimized reaction conditions (methanol to oil molar ratio, 10:1 (tetrahydrofuran (THF):methanol 1:1); reaction time 90 min; catalyst concentration 2.5 wt % and stirrer speed 650 rpm at 65 °C). Reusability of catalyst was examined up to five runs and found the catalyst was reusable up to five times without much loss of catalytic activity.