Biodiesel Production by Using Heterogeneous Catalyst from Fly Ash and Limestone

The objective of this research is to produce biodiesel from vegetable oil by using a heterogeneous catalyst. The heterogeneous catalyst was synthesized from fly ash and limestone by using wet mixing method and thermal processing. Fly ash and limestone was mixed with water and calcined in 800, 900 and 1000 degrees C. Biodiesel was produced with transesterification reaction from vegetable oil and methanol. In transesterification, vegetable oil must contain < 0.05% free fatty acid. Free fatty acid contents in vegetable oil were reduced until < 2% via esterification reaction using a sulphuric acid catalyst. In this research, biodiesel production conducted in a three-neck flask with 500 mL capacity and a magnetic stirrer. The product was analyzed using Gas Chromatography Mass Spectrometry (GCMS). The highest yield of biodiesel was obtained from B800 catalyst. The yield of biodiesel from B800, B900, B1000, K800, K900 and K1000 are 83.6%, 82%, 81.3%, 82.5%, 82% and 80.4% respectively. Biodiesel product has characterized the density, viscosity and free fatty acid content. The result showed that biodiesel product has properties that comply with Indonesian National Standard (SNI).