Synthesis of MgO-K2O compound and its application as a heterogen catalyst for making biodiesel from crude palm oil offgrade using ultrasonic waves.

The heterogeneous catalysts in biodiesel synthesis is more environmentally friendly and reusable. Alkaline earth oxides are less alkaline than alkaline oxides. Biodiesel is an alternative fuel, which has been started to be developed as a renewable energy. The aim of this study was to synthesize biodiesel from low-quality crude palm oil (CPO) with heterogeneous catalyst of MgO-K2O using ultrasonic waves. The stages in this study were (a) activation of natural zeolites, (b) refining of low quality of CPO, (c) synthesis of MgO-K2O catalyst at ratio of 10 : 1, 10 : 2, 10 : 3 (MgO : KOH) and (d) transesterification of esterified CPO (variations in the amount of catalyst 10%, 15%, and 20%). This research achieved the optimum conditions for methyl ester synthesis at ratio of 10 : 2 (MgO : KOH) of catalyst composition (15% w/w of oil), and the yield was 88.086%. The character of the methyl ester was in accordance of Indonesian biodiesel standard, therefore, the methyl ester obtained has the potential as biodiesel. The composition of the synthesized methyl ester were 1.96% methyl myristate, 40.42% methyl palmitate, 44.32% methyl oleate, and 7.46% methyl stearate. [ABSTRACT FROM AUTHOR]