The focus of this review is on the use of non-conventional heterogeneous catalysts for biodiesel synthesis. The review is based on published works that have utilized these non-conventional catalysts for biodiesel synthesis with very good biodiesel yield. The non-conventional catalysts under consideration in this review are those obtained majorly from egg shells. These materials are generally waste materials which several publications had reported to contain high content of calcium oxide. Utilization of these waste materials as catalysts reduces catalyst cost, promotes environmentally benign process and serves as source of income if biodiesel is to be commercialized. Results reported 80 to 90% yield of biodiesel using some of these non-conventional catalysts.
Key words: Biodiesel, seed oils, egg shells.
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