Modification of Nanozirconia with Sulfuric Acid and Calcium Oxide as Heterogeneous Catalysts for Biodiesel Production from Used Coconut Cooking Oil

The commercial zirconia nanopowder was modified using sulfuric acid and calcium oxide to synthesize SO4/ZrO2 and Zr/CaO catalysts. The wet impregnation technique was utilized to obtain SO4/ZrO2 acid catalyst, and the Zr/CaO base catalyst was produced as well using reflux method through the microwave heating process. The highest total acidity of SO4/ZrO2 catalyst was treated by 0.9 M H2SO4 and 500 °C of calcination temperature, and this catalyst was succeeded in reducing used coconut cooking oil FFA from 1.18% to 0.42% in the esterification process. The highest total alkalinity was reached using 1% w/w Zr/CaO and 900 °C of calcination temperature, and this catalyst was applied in the transesterification stage and successfully converted used coconut cooking oil into biodiesel by 62.25%. The formation of biodiesel was confirmed by the presence of methyl laurate (50.48%), methyl myristate (19.05%), methyl stearate (11.05%), methyl 11-octadecanoic (6.09%), methyl octanoate (5.25%), methyl decanoate (5.05%), and methyl octadecanoate (3.03%).