Conversion of Used Cooking Oil into Biodiesel by Utilizing Zirconia Catalyst as Acid Catalyst (SO4/ZrO2) and Base Catalyst (ZrO2/CaO)

Zirconium (ZrO2) was synthesized from Zirconium Oxychloride (ZrOCl2.8H2O) using hydrothermal method. Modification of ZrO2 as an acid catalyst (SO4/ZrO2) was made by adding 0.5; 1; and 1.5 M sulfuric acid solutions to ZrO2. The sulfation process was confirmed by formation of SO42− ion spectrum in 1238–1001 cm−1 region and resulted presence of elemental sulfur with mass percentage of 1.36%. The catalyst acidity test showed 1.5 M SO4/ZrO2 catalyst as catalyst with the highest acidity value. The application of 1.5 M SO4/ZrO2 catalyst in the esterification reaction of used cooking oil resulted decreasing of free fatty acid content up to 55.33%. In the another, preparation of basic catalyst, ZrO2/CaO was carried out by the addition of Calcium oxide (CaO) to ZrO2 in three concentrations group of 25, 30, and 35%. The results, we found the catalyst with optimal basicity value in group 30% ZrO2/CaO. In addition, the 30% ZrO2/CaO catalyst has CaZrO3 and lime-CaO crystal phases; exfoliated surface morphology and result Zirconium and Calcium of 7.41 and 42.83%, respectively. Furthermore, biodiesel production from used cooking oil using 30% ZrO2/CaO catalyst produces biodiesel with good conversion percentage of 94.00%.