Biodiesel Production Using Catalyst Na₂O/Fly Ash from Waste Cooking Oil (WCO) with Transesterification Process

Abstract

The consumption of fuel oil in all countries in the world is always increasing. Indonesia is one of the countries that are still dependent on fuel oil, especially for transportation and industry. Biodiesel is known as an alternative to diesel fuel that is believed to be able to overcome the problems of world energy needs. One of the raw materials that have the potential to be biodiesel is Waste Cooking Oil (WCO). This research aims to study the Na2O/Fly ash catalyst preparation process used for the transesterification reaction of WCO into biodiesel, study of purifying WCO as a raw material in biodiesel, analyze the effect of the methanol molar ratio to oil, catalyst loading and reaction time on the transesterification process in terms of the yield of the reaction, density, viscosity and an acid number of biodiesel product. The research method was begun preparation of Na2O/Fly ash catalyst and purification of WCO with despicing and neutralization methods. Afterwards, the transesterification process was running by varying %wt of the catalyst, the molar ratio of methanol to oil, and reaction time. The percentage weight of the catalyst used is 4% and 6% to the WCO weight, the molar ratio of methanol to oil is 6:1 and 8:1, and the transesterification reaction time used is 60, 80, 100 and 120 minutes. The results showed that the Free Fatty Acids (FFA) of WCO raw material was 3.102%, but after the despicing and neutralization processes were carried out, the FFA of WCO decreased to 2.538% and 0.282%, respectively. The optimal condition for the biodiesel production process was obtained when the catalyst weight is 6% with a molar ratio of methanol to oil by 8:1 which runs in 120 minutes. In these conditions, the obtained yield of reaction results are 99,09%, density 882 kg/m3, viscosity 11.15 cSt and an acid number of 0.2244 mg KOH/g. The results of XRD analysis on the catalyst Na2O/Fly ash is dominant by alumina (Al2O3), silica (SiO2), ferrous oxide (Fe2O3), calcium oxide (CaO), and natrium oxide (Na2O) compositions. Moreover, GCMS analysis on biodiesel showed that the methyl ester content formed was 98.13%. Based on parameters above, density and acid number has met the quality standards of SNI 7182: 2015.